Percentage Increase In Diameter Research Articles

Growing or reproducing? Assessing the existence of a trade-off in the globose cactus Gymnocalycium monvillei.

Resource allocation in plants is a fundamental aspect of life history theory. In Cactaceae, the specific trade-off between sexual reproduction and vegetative growth has still not been studied. The aim of this work was to assess if there is a trade-off between growth and reproduction, and to analyse whether both growth and allocation to reproduction depend on size of the individual. In this study, we used Gymnocalycium monvillei, a globose cactus endemic to the mountains of central Argentina, as a model species. Specifically, we analysed the relationship of growth (percentage increase in diameter) and size of individuals (diameter) to seed production, seed mass, germination, and mean germination time. To relativize the effect of size on seed production, two variables were calculated: the ratio of seed production to plant size (RSPS), and the ratio of total seed mass to plant size (RSMS). We found that both seed production and total seed mass were significantly related to cactus size. However, growth was not related to seed mass or to seed production, even when they were relativized. Germination and mean germination time were not related to plant size or growth. In the studied species, a slow-growing globose cactus, we did not find a trade-off between growth and reproduction.

Acute aerobic exercise enhances cerebrovascular shear-mediated dilation in young adults: the role of cerebral shear.

Exercise-induced increases in shear rate (SR) acutely improve peripheral endothelial function, but the presence of this mechanism in cerebral arteries remains unclear. Thus, we evaluated shear-mediated dilation of the internal carotid artery (ICA), which is an index of cerebrovascular endothelial function, before and after exercise. Shear-mediated dilation was measured with 30 s of hypercapnia in 16 young adults before and 10 min after 30 min of sitting rest (CON) or three cycling exercises on four separate days. The target exercise intensity was 80% of oxygen uptake at the ventilatory threshold. To manipulate the ICA SR during exercise, participants breathed spontaneously (ExSB, SR increase) or hyperventilated without (ExHV, no increase in SR) or with ([Formula: see text], restoration of SR increase) addition of CO2 to inspiratory air. Shear-mediated dilation was calculated as a percent increase in diameter from baseline. Doppler ultrasound measures ICA velocity and diameter. The CON trial revealed that 30 min of sitting did not alter shear-mediated dilation (4.34 ± 1.37% to 3.44 ± 1.23%, P = 0.052). ICA dilation after exercise compared with preexercise levels increased in the ExSB trial (3.32 ± 1.37% to 4.74 ± 1.84%, P < 0.01), remained unchanged in the ExHV trial (4.07 ± 1.55% to 3.21 ± 1.48%, P = 0.07), but was elevated in the [Formula: see text] trial (3.35 ± 1.15% to 4.33 ± 2.12%, P = 0.04). Our results indicate that exercise-induced increases in cerebral shear may play a crucial role in improving cerebrovascular endothelial function after acute exercise in young adults.NEW & NOTEWORTHY We found that 30-min cycling (target intensity was 80% of the ventilatory threshold) with increasing shear of the internal carotid artery (ICA) enhanced transient hypercapnia-induced shear-mediated dilation of the ICA, reflecting improved cerebrovascular endothelial function. This enhancement of ICA dilation was diminished by suppressing the exercise-induced increase in ICA shear via hyperventilation. Our results indicate that increases in cerebral shear may be a key stimulus for improving cerebrovascular endothelial function after exercise in young adults.

Formulation Development and Invitro Evaluation of Gliclazide Pellets using Superdisintegrants by Extrusion Spheronization Technique

Introduction: Gliclazide is a sulfonylurea derivative used for the treatment of type 2 Diabetes, it is an anti-diabetic drug it is marketed under the brand name Diamicron. It is taken orally and used when dietary changes, lack of exercise, and weight loss are not sufficient. &#x0D; Aim: The principal objective of this work was to develop, formulate and evaluate the pellet formulations prepared with the incorporation of different super disintegrants in different ratios and in different combinations. In this research work, the drug gliclazide was chosen as a model drug and it was formulated into fast-dissolving pellets, which can be compressed into pelltabs and can also be filled into capsules. &#x0D; Methods: Pellets were prepared by extrusion and Spheronization containing microcrystalline cellulose (MCC) and using gliclazide as a model drug with different super disintegrants namely croscarmellose sodium, crospovidone and sodium starch glycolate in different ratios, and in different combinations. Thus, in the present study, gliclazide pellets were developed using Extrusion-Spheronization for immediate drug delivery. The pellets were evaluated for percentage drug content, flow properties, friability, size analysis, shape analysis, disintegration test, and dissolution studies. Preformulation studies were then performed using solubility studies, partition co-efficient studies, infrared spectroscopy, and drug-excipients compatibility studies between the drug and selected excipients (croscarmellose sodium, crospovidone, and sodium starch glycolate) investigated.&#x0D; Results: Formulations containing MCC, super disintegrants, and drugs in different ratios of 60/0/40, 55/5/40, and 50/10/40 w/w of croscarmellose sodium, crospovidone, and sodium starch glycolate were found to show faster release of the drug for 9 hours. Croscarmellose sodium releases the drug as it disintegrates the &#x0D; &#x0D; pellets. Sodium starch glycolate releases the drug by inducing swelling in the pellet &#x0D; matrix. Unlike the other two super disintegrants, there was no apparent change in the swelling capability of the pellets of polymer crospovidone (Polyplasdone XL10) in water. The percentage increase in diameter for Ac-Di-Sol (croscarmellose sodium), Primojel (sodium starch glycolate), and Polyplasdone XL10 were 104%, 251%, and 29% in water.&#x0D; Conclusions: Various types of super disintegrants can be investigated for their suitability in formulating pellets. In vivo drug release rate, and bioavailability studies on animals and humans may be carried out to assess the superiority of the pellets over the tablet dosage form.

EFFECT OF GENETIC GAIN IN DIAMETER AND WOOD DENSITY ON ADVANCED GENERATION BREEDING STRATEGY OF ACACIA MANGIUM IN INDONESIA

Breeding of Acacia mangium in Indonesia was initially focused on selection for improving growth and stem form. Changes in wood density which resulted from selection for improved growth was impacted by adverse correlation between the both traits. This study aimed to quantify genetic gain in the diameter and wood density from two A. mangium breeding generations and to use this information in developing breeding strategy to improve both traits simultaneously. Materials were obtained from 4.5-year-old trees in a progeny trial consisting of families from first (F-1) and second (F-2) generations along with infused families (F-0) as control. Genetic gain was calculated as the percent increase in diameter and wood density from F-1 and F-2 over the control. Diameter and wood density from F-1 and F-2 were higher than F-0. Genetic gains for diameter increased from 3.7% in F-1 to 7.0% in F-2. Conversely, gain for wood density decreased from 1.9% in F-1 to 0.3% in F-2. Correlations between diameter and wood density varied from weak to moderate along the stem sections. The results imply a combined approach incorporating selection for diameter and wood density in mixed-breeding generations will provide simultaneous improvement in both traits.

Flow Mediated Vasodilation In Response To 3-Weeks Of Moderate Altitude Exposure

The effects of moderate altitude on the cardiovascular system is an extensively researched subject, but no definitive timeline regarding the vascular acclimatization for flow mediated vasodilation (FMD) measurements is currently available in the scientific literature. It has been suggested that 3 wks might be sufficient (Frick et al., 2006). However, if this amount of time is not sufficient it will complicate data interpretation. PURPOSE: To assess the timeline of acclimatization to moderate altitude (2,130 m), specific to FMD in healthy young males. METHODS: After spending ≥ 4 weeks at lower altitude (331-1,197 m), 5 male subjects (18.6±1 yr; 71.8±8.7 kg; 1.8±0.04 m; 22.8±1.9 kg/m2) were tested within 1 wk±1 day of arrival to moderate altitude (V1) and were tested again at 2 wks (V2) and 3 wks (V3) after their initial arrival. Heart rate (HR), blood pressure (BP; systolic, SBP; diastolic, DBP), and brachial artery diameter were measured (using Brachial Analyzer) during baseline (BL) and after 5 min of forearm cuff occlusion (250 mmHg). FMD was assessed as the percent increase in diameter after the cuff occlusion. RESULTS: When comparing V1, V2, and V3, HR was no different between the visits (63±10 vs. 57±11 vs. 64±20 bpm; p=0.52 for V1 vs. V2 vs. V3, respectively). SBP was significantly higher in V1 compared to V2 and V3 (116±6 vs. 106±11 vs. 106 ±12 mmHg; both p<0.05). DBP was no different (63±9 vs. 57±9 vs. 59±6 mmHg; p=0.43). BL diameter was also not different between the visits (8.1±1.5 vs. 7.5±1.5 vs. 7.5±1.2 mm; p=0.69). FMD showed a trend toward a difference between the three visits (5.1±1.1 vs. 6.5±1.6 vs. 5.0±1.5%; p=0.07). CONCLUSION: After 3 wks of exposure to moderate altitude, it appears that FMD may continue to fluctuate. This suggests that additional measurements beyond 3 wks should be obtained to determine a better timeline for when vascular acclimatization has been achieved. This will allow better guidance for FMD measurements obtained in subjects at altitude. Supported by the State of Arizona Technology and Research Initiative Fund (TRIF)

Differential Interstrain Susceptibility to Vertebrobasilar Dolichoectasia in a Mouse Model.

Vetebrobasilar dolichoectasia is characterized by arterial elongation, dilation, and tortuosity and leads to high risks of ischemic stroke. Our aim was to investigate the differential susceptibility to elastase-induced vertebrobasilar dolichoectasia induction in 2 different mouse strains. Elastase (25 mU) was injected into the cisterna magna in C57BL/6J (n = 36) and 129/SvEv (SV129) (n = 36) mice. Control animals were injected with heat-inactivated elastase (n = 12 for each strain). At 3, 7, 14, and 28 days after elastase injection, MICROFIL polymer perfusion was performed. The arterial tortuosity index and the percentage increase in diameter were calculated for the basilar artery. Arterial samples were processed for conventional histologic examination, immunostaining, and matrix metalloproteinase expression. A ≥50% increase in diameter and a tortuosity index of ≥10 for the basilar artery were used to indicate success in achieving vertebrobasilar dolichoectasia. Successful vertebrobasilar dolichoectasia induction was noted in 67% (18 of 27) of the C57BL/6J strain versus 0% (0 of 19) of the SV129 strain (P < .001). Vertebrobasilar dolichoectasia was not observed in sham-operated controls. Both the tortuosity index and diameter increase for the basilar artery were greater in the C57BL/6J strain compared with the SV129 strain (56.3% ± 16.4% versus 21.1% ± 21.6% for diameter, P < .001; 17.4 ± 7.6 versus 10.4 ± 3.8 for tortuosity index, P < .001). Expression of pro-matrix metalloproteinase-2 and pro- and active matrix metalloproteinase-9 was increased in elastase-injected C57BL/6J animals compared with elastase-injected SV129 animals (P = .029, 0.029, and 0.029, respectively). Inflammation scores were significantly higher in C57BL/6J animals versus SV129 animals (P < .001). C57BL/6J subjects demonstrated arterial wall dilation and elongation characterized by internal elastic lamina disruption, muscular layer discontinuity, inflammatory cell infiltration, and high matrix metalloproteinase expression in the media. C57BL/6J mice demonstrated greater susceptibility to vertebrobasilar dolichoectasia induction than SV129 mice.

Impact of Plying on the Physical Properties of Vortex and Other Spun Yarns

The physical properties of two ply yarns made from vortex, ring, compact, and rotor singles have been investigated by changing ply twist factor. The physical parameters like yarn diameter, plied yarn length, twist liveliness have been found to be significantly affected by the ply twist factor. Though plying increases the yarn diameter for all, the percentage increase in diameter with respect to single yarn is the minimum for vortex yarns. The ply twist factor at which the real contraction starts is also the lowest for vortex yarns. Amongst the plied yarns, those made from rotor yarns show minimum twist liveliness. A minimum ply twist threshold exists below which hockles (a hole like structure) in ply yarns are observed.

Microvascular Effects of Subatmospheric Pressure in Striated Muscle

Topical application of subatmospheric pressure (TASAP) promotes faster wound healing, but tissue effects are not entirely understood. This study investigated microvascular effects of TASAP in striated muscle with the hypothesis being that TASAP elicits arteriolar vasodilation and decreases interstitial accumulation of protein. Rat cremasteric microcirculation was directly examined in two experiments utilizing a novel technique. First, TASAP was applied to the cremaster in three experimental groups and a non-TASAP control group. Arteriolar diameters were directly measured before and after TASAP. In experiment two, intravascular fluorescein isothiocyanate (FITC)-labeled albumin and topical leukotriene B4 (LTB4) were delivered to the cremaster. Microvascular permeability was assessed by measuring the accumulation/disappearance of FITC-albumin in the interstitial tissue. TASAP produced significant arteriolar vasodilation compared with control values. The mean maximum percent increase in diameter with TASAP was 8.70% at -2 kPa (p < 0.05), 7.16% at -4 kPa (p < 0.05), and 10.43% at -6 kPa (p < 0.01). TASAP decreased interstitial FITC-albumin by 26.3% (p < 0.008) following LTB4; the control group showed a steady increase in interstitial FITC-albumin. These results support the hypothesis that TASAP elicits significant arteriolar vasodilation with a subsequent increase in blood flow as well as a decrease in interstitial protein accumulation.

61 APPLICATION OF AN OPEN DEVICE TO VITRIFY EQUINE IN VITRO-PRODUCED EMBRYOS

Recently, we reported a &gt;50% normal pregnancy rate for vitrified/warmed equine expanded blastocysts after blastocoele collapse via micromanipulation and vitrification in fine-diameter (250-µm) pipettes (Choi et al. 2011 Theriogenology 76, 143). This vitrification system has also yielded high pregnancy rates after transfer of blastocysts produced by intracytoplasmic sperm injection and embryo culture (IVP embryos) in our clinical program (unpublished data). However, the pipettes are difficult to load and must be manipulated to expel the embryo after warming. To improve this technique, we modified the pipettes by cutting their tip lengthwise and flaming the surface smooth, and we investigated the use of these open devices (designated “Sujo”) for vitrification of equine IVP embryos. Embryos were held in 1.5 M ethylene glycol in DMEM/F-12 + 20% FBS for 5 min; then moved to 7 M ethylene glycol and 0.6 M galactose; and within 1 min loaded on a Sujo with a minimum amount of medium, plunged into liquid N2, and inserted into a 5-mL cryovial or 0.5-mL straw before being stored in liquid N2. Embryos were warmed by placing the Sujo tip in 0.3 M sucrose in base medium (Dulbecco’s phosphate buffered saline with 0.1% glucose, 36 mg L–1 of pyruvate, and 0.4% BSA). Embryos were left in this medium for 1 min and then moved to 0.15 M and then 0 M sucrose in base medium for 5 min each. In Experiment 1, we examined whether embryos stayed on the Sujo device. A total of 23 cleaved embryos were vitrified individually on Sujos; all of them were successfully recovered after warming. In Experiment 2, 18 IVP blastocysts were vitrified on Sujos (1 to 3 per Sujo), then warmed and cultured in 500-µL DMEM/F-12 + 20% FBS in an atmosphere of 5.5% CO2, 5% O2, and 89.5% N2 at 38.2°C for 3 days. All 18 embryos grew in vitro. The average percentage increase in diameter (mean ± SEM) for embryos vitrified at 1 per Sujo was 73% (from 167 ± 4 to 289 ± 16 µm, 11 embryos); 2 per Sujo, 98% (from 187 ± 27 to 387 ± 106 µm, 4 embryos); and 3 per Sujo, 96% (from 176 ± 4 to 342 ± 51 µm, 3 embryos). There was no significant difference in percentage growth among treatments (one-way ANOVA; SigmaPlot 11.0). In Experiment 3, 11 IVP embryos were vitrified after loading singly on Cryolocks®, then warmed and cultured as above. One embryo did not grow; the remaining 10 embryos grew an average of 73% (from 170 ± 3 to 294 ± 31 µm). In a preliminary study, 2 in vivo-recovered blastocysts (277 and 411 µm) were vitrified singly on Sujos and then warmed and cultured in vitro for 24 h under the above conditions increased in diameter to 594 and 729 µm, respectively. In conclusion, an open device can be used effectively for vitrification of equine IVP embryos. Further studies are needed to determine the efficiency of this system for vitrification of expanded equine blastocysts and the pregnancy rate of these embryos after transfer. Supported by the American Quarter Horse Foundation, the Link Equine Research Endowment Fund, Texas A&amp;M University, and by Ms. Kit Knotts.

2132 IMPACT OF RENAL TRANSPLANT ON VASCULOGENIC AND NEUROGENIC DETERMINANTS OF ERECTILE DYSFUNCTION IN PATIENTS WITH CHRONIC RENAL FAILURE

You have accessJournal of UrologyTransplantation & Vascular Surgery: Renal Transplantation, Vascular Surgery I1 Apr 20122132 IMPACT OF RENAL TRANSPLANT ON VASCULOGENIC AND NEUROGENIC DETERMINANTS OF ERECTILE DYSFUNCTION IN PATIENTS WITH CHRONIC RENAL FAILURE Bhuvanesh Nanjappa, Shrawan Kumar Singh, Ravimohan Mavuduru, Manish Modi, Mukut Minz, Arup Kumar Mandal, and Vinay Sakhuja Bhuvanesh NanjappaBhuvanesh Nanjappa Chandigarh, India More articles by this author , Shrawan Kumar SinghShrawan Kumar Singh Chandigarh, India More articles by this author , Ravimohan MavuduruRavimohan Mavuduru Chandigarh, India More articles by this author , Manish ModiManish Modi Chandigarh, India More articles by this author , Mukut MinzMukut Minz Chandigarh, India More articles by this author , Arup Kumar MandalArup Kumar Mandal Chandigarh, India More articles by this author , and Vinay SakhujaVinay Sakhuja Chandigarh, India More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2302AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Erectile dysfunction (ED) is common in chronic renal failure, it has multifactorial causes which may get reverse following transplantation. Present study was conducted to assess endothelial dysfunction by flow mediated dilatation (FMD) and neuropathy by sympathetic skin response (SSR) and nerve conduction studies (NCS) in uremics before and after renal transplantation. METHODS Patients awaiting transplantation were subjected to history, clinical evaluation, IIEF-5 questionnaires. SSR and NCS were assessed using Nicolet Biomedical EA-4. FMD of brachial artery estimated using high resolution ultrasound after occluding brachial artery for 5 minutes, expressed as maximum percentage increase in diameter. Patients were evaluated again for above parameters, 3 months after successful transplantation. The statistical analysis was performed by paired 't' test and Pearson coefficient of correlation. RESULTS Total 171 male patients underwent renal transplantation during the study period. Thirty nine patients with diabetes mellitus, four with graft dysfunction and one with multiple myeloma were excluded from the study. Data of remaining 127 patients were analyzed. Prevalence of ED before and after transplantation was 75.6% and 55.9% respectively (p < 0.001). Serum testosterone levels, FMD and IIEF scores improved significantly (8.05±1.70 to 9.43±2.16, p < 0.000), (12.61±6.15% vs 20.10±8.60, p<0.000 and 17.47±4.30 vs. 19.26±4.41, p<0.000). IIEF scores correlated significantly with age (r= −0.298, p<0.001), FMD (r=444, p<0.000) & cholesterol (r=−0.178, p<0.045). FMD correlated negatively with age (r=−0.284, p<0.001). There was no significant difference in IIEF score with respect to the type of renal arterial anastomosis (Internal iliac 19.78±4.52 vs. External iliac 18.79±4.28; p=0.984). SSR and NCS were abnormal in 20 and 28 patients before and 9 and 8 patients after transplantation, respectively. IIEF and FMD were significantly low in patients with abnormal NCS and SSR. CONCLUSIONS Prevalence of ED is high in uremics and improves following transplantation. The improvement is associated with improvement in vasculogenic and neurogenic determinants of erectile function. A substantial number of them still may continue to have ED. It may improve with passage of time in patients with normal graft function. However, it requires further study with longer follow-up. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetailsCited byPyrgidis N, Mykoniatis I, Sokolakis I, Minopoulou I, Nigdelis M, Sountoulides P, Verze P, Hatzichristodoulou G and Hatzichristou D (2020) Renal Transplantation Improves Erectile Function in Patients with End-Stage Renal Disease: A Systematic Review and Meta-AnalysisJournal of Urology, VOL. 205, NO. 4, (1009-1017), Online publication date: 1-Apr-2021. Volume 187Issue 4SApril 2012Page: e861 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Bhuvanesh Nanjappa Chandigarh, India More articles by this author Shrawan Kumar Singh Chandigarh, India More articles by this author Ravimohan Mavuduru Chandigarh, India More articles by this author Manish Modi Chandigarh, India More articles by this author Mukut Minz Chandigarh, India More articles by this author Arup Kumar Mandal Chandigarh, India More articles by this author Vinay Sakhuja Chandigarh, India More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

The role of the endothelium in migraine

Migraine, characterized by throbbing cephalalgia, has long been referred to as a ‘‘vascular headache’’ disorder. This stems from the putative role of the extracerebral dural and meningeal vasculature as the end organ of migraine pain, following release of inflammatory neurotransmitters from trigeminal nerve endings. Recognition of migraine as a risk factor for stroke has raised questions about the role of cerebral vessels. Associations of migraine with variant angina, Raynaud’s disorder, retinopathy, livedo reticularis and pre-eclampsia has led to speculation of systemic involvement of the vasculature, particularly the endothelium (1). Endothelial dysfunction, a precursor to atherosclerosis, is characterized by endothelial cell activation (manifested by inflammation and hypercoagulability) and vascular reactivity impairment. In the investigation of Perko et al. (2), the authors explore systemic endothelial-dependent vasodilatation in migraine patients and healthy controls. The experiments involve end-diastolic measurements of the brachial artery diameter before and after blood pressure cuff–induced hyperemia. Flow-mediated dilatation (FMD) refers to the percentage increase in diameter between the two measurements, and low values reflect impaired reactivity, a functional component of endothelial dysfunction. The authors found no differences in FMD between migraineurs and controls, nor between migraineurs with and without aura, suggesting a lack of systemic endothelial involvement. A strength of the study lies in the careful selection of the population, excluding those with hypertension, hypercholesterolemia, diabetes, abnormal body mass index (BMI) and known cardiovascular disease. Associated with vascular risk factors and predictive of vascular ischemic events, endothelial dysfunction has been referred to as ‘‘the ultimate risk of the risk factors’’ (3). Migraine, particularly with aura, has also been associated an elevated cardiovascular risk profile (4). By excluding subjects with or at risk of vascular disease, the design best allows for examination of the unconfounded migraine-endothelial function relationship. The authors go a step further by excluding those with increased carotid intima-media thickness (IMT), a structural marker of subclinical atherosclerosis. Some studies have shown a correlation between IMT and FMD (5), whereas others have not (6). If these structural and functional markers are related, exclusion of one of these markers may bias against finding differences between groups for the other. How do the findings of Perko, et al. of non-altered FMD in migraineurs fit in with the accumulating literature on this topic? As the authors summarize in their well-researched discussion, their findings concur with those of one study (7) but conflict with the results of several others (8–11). A recently published study, similarly measuring FMD and IMT in migraine, excluded persons with known risk factors for vascular disease, except for elevated BMI (12). There were no differences in FMD between migraine (with and without aura) patients and controls, except in a subgroup with transformed migraine. FMD did, however, correlate inversely with carotid IMT, which was increased in all of the migraine subgroups. This could be expected to occur if IMT was an earlier marker of disease, but wall thickening is usually found to follow rather than precede endothelial dysfunction. In light of the discrepant results from the handful of published studies, it is interesting to reflect on the findings of Napoli et al., who investigated vascular reactivity in migraine by examining both the endothelial and vascular smooth muscle cell (VSMC) components (13). They used plethysmography measurements of forearm blood flow (FBF) during brachial artery infusions of acetylcholine (Ach), an endothelium-dependent vasodilator, and nitroprusside, a vasodilator directly acting on VSMC. In addition to this they measured forearm production of NO, a reflection of endothelial activation, and cyclic guanosine monophosphate (cGMP),

Humming Is as Effective as Valsalva’s Maneuver and Trendelenburg’s Position for Ultrasonographic Visualization of the Jugular Venous System and Common Femoral Veins

The purpose of this study is to compare ultrasonographic visualization of the jugular and common femoral veins by using a novel technique (humming) and 2 conventional techniques (Valsalva's maneuver and Trendelenburg's position). The Valsalva's maneuver and Trendelenburg's position are common methods for producing venous distention, aiding ultrasonographically guided identification and cannulation of the jugular and common femoral veins. We hypothesize that humming is as effective as either Valsalva's maneuver or Trendelenburg's position for distention and ultrasonographic visualization of these procedurally important blood vessels. Herein, we investigate a new method of venous distension that may aid in the placement of central venous catheters by ultrasonographic guidance. Healthy, normal volunteers aged 28 to 67 years were enrolled. Each subject's internal jugular, external jugular, and common femoral veins were measured in cross-section by ultrasonograph during rest (baseline), humming, Valsalva's maneuver, and Trendelenburg's position. Three measurements were recorded per observation in each position. Subjects were used as their own controls, and measurements were normalized to percentage increase in diameter during each maneuver or position for later comparison. The study population consisted of 7 subjects, with a mean age of 47 years. Cross-sectional area was calculated for each vessel in 3 groups: baseline/control, Valsalva, Trendelenburg, and humming. The mean percentage change (+/-SD) relative to baseline cross-sectional area of the jugular vessels for each subject were external jugular vein: humming 134%+/-25% (95% confidence interval [CI] 124.9% to 146.9%), Valsalva 136%+/-23% (95% CI 121.3% to 147.5%), Trendelenburg 137%+/-32% (95% CI 120.7% to 156.9%); internal jugular vein: humming 137%+/-27% (95% CI 119.4% to 148.2%), Valsalva 139%+/-24% (95% CI 122.4% to 148.7%), Trendelenburg 141%+/-35% (95% CI 116.5% to 156.5%); common femoral vein: humming 131%+/-15% (95% CI 120.4% to 139.1%), Valsalva 139%+/-18% (95% CI 127.9% to 150.4%), Trendelenburg 132%+/-24% (95% CI 113.3% to 142.9%). All 3 maneuvers distended the external jugular, internal jugular, and common femoral veins compared to baseline. There was no important difference in magnitude of cross-sectional area between any of the 3 maneuvers when compared with one another. Humming shares many physiologic similarities to Valsalva's maneuver and may be more familiar and easier to perform during procedures such as ultrasonographically guided central venous catheter placement and insertion of external jugular intravenous catheters.

Changes in Cross-Sectional Area of Hamstring Anterior Cruciate Ligament Grafts as a Function of Time Following Transplantation

To measure the cross-sectional area (CSA) of hamstring anterior cruciate ligament (ACL) grafts in humans up to 2 years postoperatively and to estimate the appropriate graft-notch distance (the distance between ACL graft and roof or wall of the notch) at surgery. Case series. Fifty-nine patients, who had consented to have a magnetic resonance imaging (MRI) evaluation postoperatively, underwent endoscopic ACL reconstruction using 3- to 5-strand autogenous hamstring tendons. Intraoperatively, the CSA of the graft was measured using a custom-made area micrometer. Postoperatively, 115 axial MRIs of the grafts (48 at 3 months, 44 at 12 months, and 23 at 24 months) were obtained. They were transmitted to a personal computer and the CSAs of the grafts' midsubstance were calculated. To evaluate the accuracy of the MRI measurement, another 15 patients who consented to have MRI 2 days after surgery were selected and intraoperative graft CSA measurements and graft axial MRI were performed 2 days after surgery. The CSAs of the grafts measured by MRI 2 days after surgery were well correlated with those directly measured intraoperatively (gamma = 0.905). The CSA of the grafts measured intraoperatively was 43 +/- 5 mm2, and those estimated by MRI at 3, 12, and 24 months were 50 +/- 9 mm2, 54 +/- 9 mm2, and 48 +/- 12 mm2, respectively. The increase in graft diameter at 3, 12, and 24 months was 9% +/- 8%, 13% +/- 10%, and 7% +/- 12%, respectively. In humans, the increase in CSA of the ACL graft was smaller compared with previous animal studies. The graft CSA increased up to 29% (13% in diameter) 12 months after surgery. When a 95% confidence interval was used, the percent increase in diameter of the reconstructed graft was estimated to be less than 32% in 95% of the cases. When the graft diameter was 7, 8, or 9 mm, a 1.1-, 1.3-, or 1.4-mm graft-notch distance, respectively, was suitable for impingement-free graft during postoperative periods with 95% of probability. Level IIII.

Effect of fiber friction, yarn twist, and splicing air pressure on yarn splicing performance

The impact of fiber friction, yarn twist, and splicing air pressure on mechanical and structural properties of spliced portion have been reported in the present paper. The mechanical properties include the tensile and bending related properties and, in the structural properties, the diameter and packing density of the splices are studied. A three variable three level factorial design approach proposed by Box and Behnken has been used to design the experiment. The results indicate that there is a strong correlation between retained spliced strength (RSS) and retained splice elongation (RSE) with all the experimental variables. It has been observed that RSS increases with the increase in splice air pressure and after certain level it drops, whereas it consistently increases with the increase in yarn twist. The RSE increases with the increase in both fiber friction and yarn twist. It has also been observed that the yarn twist and splicing air pressure have significant influence on splice diameter, percent increase in diameter and retained packing coefficient, but the fiber friction has negligible influence on these parameters. Yarn twist and splicing air pressure has a strong correlation with splice flexural rigidity, where as poor correlation with retained flexural rigidity.

Growth hormone therapy influences endothelial function in children with renal failure.

Endothelial dysfunction, an early step in atherogenesis, is prevalent in children with renal insufficiency. Endothelial dysfunction in growth hormone deficiency is reversed by growth hormone (rhGH) therapy. Renal failure induces growth hormone resistance at the receptor and post-receptor level, which can be overcome by rhGH therapy. This study investigates the influence of rhGH therapy in children with renal failure on flow-mediated dilation (FMD) of the brachial artery, a marker of endothelial function. We studied 8 patients, who were on rhGH for at least 6 months, and 8 healthy children for comparison. FMD of the brachial artery was measured non-invasively as the percentage increase in diameter during post-ischemic hyperemia. Patients were studied at baseline, after 4 weeks interruption of rhGH therapy, and 4 weeks after resumption of therapy. FMD was significantly lower in patients (4.7%) than healthy controls (13.8%) ( P=0.01). During the administration of rhGH, FMD was significantly higher (3.9%) than during interruption of the treatment (1.4%) ( P=0.04). Our data support the theory that a disturbance in the GH-IGF axis contributes to the endothelial dysfunction of renal failure. Treatment with rhGH not only improves growth but may also favorably influence the risk for atherogenesis.

Correlation Between Preoperative and Postoperative Duplex Vein Measurements of the Greater Saphenous Vein Used for infrainguinal Arterial Reconstruction

Vein diameter measurements using B-mode Doppler ultrasound (US) are used to assess the greater saphenous vein (GSV) for bypass operations; a 2.5-3.0 mm diameter is suggested as a minimum. Preoperative measurements are made while the vein is in the low-pressure venous system. This may not reflect the distended diameter of a vein after placement in the arterial system. This study compares preoperative and postoperative GSV diameters to identify the degree of dilatation and the minimal size adequate for use in arterial bypass operations. The GSV of 11 patients undergoing an infrainguinal arterial bypass were assessed by utilizing Doppler US. Measurements were taken every 10 cm, for 70 cm, along the course of the GSV before and 4 weeks after operation. All segments showed a percent increase in diameter from the preoperative to postoperative time points; 10 cm, 38+/-; 20 cm, 31+/-; 30 cm, 16+/-; 40 cm, 26+/-; 50 cm, 23+/-; 60 cm, 28+/-; and 70 cm, 22+/-. A Bonferroni post hoc analysis between the 2 time point means showed a significant increase in means for the 2 time points of 9.49 units (Bonf p value < 0.001). Preoperative vein segments were divided into 3 categories: </= 3.0 mm, 3.1-4.0 mm, and > 4.1 mm. All showed a significant increase over time. Preoperative diameter measurements of the vein may not reflect the final distended diameter after bypass. Preoperative vein diameters </= 3.0 mm showed a significant increase of 33+/- to nearly 4.0 mm. This was the largest increase observed in any segment measured. A potential 16-33+/- increase in vein diameter should be considered in vein mapping. The rejection of small veins (</= 3.0 mm) in preoperative vein-mapping studies may not be warranted given the potential for a substantial increase in size when placed in the arterial system.

Noninvasive assessment of vascular function in the posterior tibial artery of healthy humans

Flow-mediated dilation (FMD) measures the ability of an artery to relax in response to increases in blood velocity. FMD, primarily of the brachial artery, has been used as a noninvasive method of assessing vascular health. The purpose of this study was to assess FMD in the lower legs of humans. Six healthy subjects (27 ± 6 yrs) were tested. Doppler ultrasound images of the posterior tibial artery were taken before, during, and after 5 minutes of proximal cuff occlusion. FMD was measured as the percent increase in diameter after cuff release. Vascular tone was calculated using the resting diameter as a percentage of the vessel's vasoactive range. Minimum diameter occurred during ischemia and maximal diameter occurred following reactive hyperemia with local heating. The lower leg was heated with 10 minutes of immersion in 44°C water. Mean diameters at rest, cuff, and during release were 0.267 ± 0.062, 0.162 ± 0.036, 0.302 ± 0.058 cm, respectively. FMD was 13.5 ± 6.6 % and vascular tone was 29 ± 16.3%. We also found that retesting on a second day produced mean diameter values within 8% of the first day. Larger resting diameter (decreased tone) correlated with decreased FMD (r2 = 0.73). These results suggest that FMD and vascular tone can be measured in the posterior tibial artery. This is a potentially powerful tool to non-invasively measure vascular health in the lower legs of people at risk for vascular disease.

Influence of vascular dimension on gender difference in flow-dependent dilatation of peripheral conduit arteries.

To assess the influence of initial diameter on the gender difference in flow-dependent dilatation (FDD) of the conduit artery, we measured radial artery internal diameter (echotracking), flow (Doppler) and total blood viscosity in 24 healthy (25 +/- 0.8 yr) men and women during reactive hyperemia (RH) and during a gradual hand skin heating (SH). At baseline, mean diameter (men, 2.76 +/- 0.09 vs. women, 2.32 +/- 0.07 mm, P < 0.05), flow (men, 21 +/- 4 vs. women, 10 +/- 1 ml/min, P < 0.05), and blood viscosity (men, 4.13 +/- 0.07 vs. women, 3.92 +/- 0.13 cP, P < 0.05) were higher in men but mean shear stress (MSS) was not different between groups. During RH, the percent increase in diameter was lower in men (men, 9 +/- 1 vs. women, 13 +/- 1%, P < 0.05). This difference was suppressed after correction for baseline diameter. During SH, the increase in diameter with flow was higher in women (P < 0.01). However, the increase in MSS was higher in women because of their smaller diameter at each level of flow (P < 0.01) and there was no difference between groups for the increase in diameter at each level of MSS. These results demonstrate in a direct manner that initial diameter influences the magnitude of FDD of conduit arteries in humans by modifying the value of the arterial wall shear stress at each level of flow and support the interest of the heating method in presence of heterogeneous groups.

The Relationship of Left Ventricular Mass to Endothelium-Dependent Vasodilation of the Brachial Artery in Patients with Hypertension

Although echocardiographically determined left ventricular mass and geometry predict cardiovascular morbid events in patients with hypertension, the mechanisms underlying this relation are unclear. There is considerable evidence that endothelium-dependent vasodilation is impaired in patients with hypertension. Thus, endothelial dysfunction may contribute to the mechanism that causes cardiovascular morbid events. This study was designed to examine the relationship between left ventricular geometry and endothelial function in patients with hypertension. The percentage increase in brachial arterial diameter during reactive hyperemia was examined by a high-resolution ultrasound technique in 49 patients with hypertension and 64 normotensive subjects. Patients with hypertension had an impairment of the percentage increase in brachial arterial diameter during reactive hyperemia and an increase in thiobarbituric acid-reactive substances (TBARS) compared to normotensive subjects (percentage increase in diameter 5.6 ± 3.0 vs. 8.0 ± 2.5%, p < 0.001; TBARS levels 6.1 ± 1.3 vs. 5.3 ± 1.0 nmol/ml, p < 0.001). In patients with hypertension, there was a significant correlation between the left ventricular mass index and the percentage increase in brachial arterial diameter during reactive hyperemia (r = –0.583, p < 0.001), and the percentage increase in brachial arterial diameter during reactive hyperemia varied with the pattern of left ventricular geometry (normal ventricular geometry: 7.7 ± 2.6%; concentric remodeling: 5.2 ± 2.3%; eccentric hypertrophy: 4.2 ± 1.8%; concentric hypertrophy: 2.9 ± 2.6%). We conclude that (1) flow-mediated endothelium-dependent vasodilation in the brachial artery is impaired in patients with hypertension, (2) a relationship exists between the left ventricular mass index and flow-mediated endothelium-dependent vasodilation in the brachial artery in patients with hypertension and (3) increased oxidative stress may play a role in the endothelial dysfunction in patients with hypertension.

Troglitazone reduces reactive oxygen species generation by leukocytes and lipid peroxidation and improves flow-mediated vasodilatation in obese subjects.

Because troglitazone has been shown to have antioxidant properties, we investigated whether troglitazone administration to obese subjects causes a reduction in (1) reactive oxygen species (ROS) generation by polymorphonuclear leukocytes (PMNLs) and mononuclear cells (MNCs) and (2) lipid peroxidation as reflected in the plasma concentrations of 9-hydroxyoctadecadienoic acid (9-HODE) and 13-hydroxyoctadecadienoic acid (13-HODE). Seven obese subjects were given 400 mg/d troglitazone for 4 weeks. Blood samples were obtained before troglitazone administration and at weekly intervals thereafter. Insulin concentrations fell significantly at week 1 and remained low at weeks 2 and 4 (P:<0.001). ROS generation by PMNLs fell to 77.6+/-25.1% of the basal at week 1 and 47.9+/-41.1% at week 4 (P:<0.001). ROS generation by MNCs fell to 59.8+/-15.7% of the basal at week 1 and 35.1+/-17.6% at week 4 (P:<0.001). 9-HODE and 13-HODE concentrations fell significantly from 787.4+/-52.4 and 713. 1+/-44.7 pg/mL to 720.4+/-66.7 (P:<0.004) and 675.2+/-65.0 pg/mL (P:<0.01) after 4 weeks, respectively. Postischemic dilatation of the brachial artery was measured by ultrasonography. The mean percent dilatation after forearm ischemia before and after troglitazone was 5.5+/-3.01% and 8.75+/-3.37% (P:<0.02), respectively. The percent increase in diameter after nitroglycerin was 17.08+/-1.18% before troglitazone, whereas it was 18.9+/-1.91% (P:<0.02) after troglitazone. We conclude that troglitazone has a potent and rapid biological inhibitory effect on ROS generation by PMNLs and MNCs and that it inhibits lipid peroxidation significantly. These changes are associated with a significant improvement in postischemic flow-mediated vasodilation in the brachial artery over a relatively short period of 4 weeks.