T1 T5 Research Articles

Up-regulation of TNF-α in neurons of dorsal root ganglia and spinal cord during coronary artery occlusion in rats

Knowledge about the physiologic and pathophysiologic roles of tumor necrosis factor-α (TNF-α) in acute myocardial ischemia/infarction is still very limited. Evidence implies that TNF-α is involved in neural activity including nociception in peripheral and central nervous system. Current study was designed to examine the association of change in TNF-α and its mRNA in upper thoracic dorsal root ganglia and spinal cord (T1–T5) during acute myocardial ischemia/infarction induced by coronary artery occlusion (CAO) in rats. The experiment was performed using immunohistochemistry, enzyme immunoassay, in situ hybridization and real time reverse transcription-polymerase chain reaction techniques. At 0.5 h, 1 h, 3 h and 6 h of acute myocardial ischemia/infarction, TNF-α was mainly up-regulated in a sub-population of small and medium neurons and satellite cells in the dorsal root ganglia (DRG) and spinal neurons, mainly in laminae I, II and V, VI of the spinal dorsal horn of upper thoracic segments. The up-regulation of TNF-α mRNA was observed at 30 min of CAO, which was statistically significant, compared with the control and the sham surgery groups ( P < 0.01). The TNF-α mRNA was located in the satellite cells and afferent neurons of the DRG and spinal neurons, located mainly in laminae II–VI. The findings indicate an association of up-regulation of TNF-α in DRG and spinal cord with acute myocardial ischemia/infarction, suggesting that TNF-α may be associated with the nociception initiated by acute myocardial ischemia/infarction, while the pathophysiological role needs to be studied.

Anterior tooth wear and retention type until 5 years after orthodontic treatment

Objectives. To study occlusal wear of anterior teeth in orthodontic patients retained with different retainers until 5 years post-treatment, and to investigate whether type of retention influences occlusal wear. Material and methods. Orthodontic patients (n=222), aged 15 years maximally at the start of treatment, were followed until 5 years post-treatment. In the maxilla, a retainer bonded on all six teeth or a removable retainer was used; in the mandible, a lingual retainer was bonded on all anterior teeth or on canines only. Dental casts were analyzed before treatment (T0), after treatment (T1), and 5 years post-treatment (T5). Incisal and canine wear were scored by applying a grading scale. Intercanine width, overjet, and overbite were measured with an electronic caliper. Statistics used were: Paired samples t-test for differences over time; Pearson correlation coefficients for associations between wear and retention type; and backward linear regression for influence of retention type on wear. Results. There was an increase in wear during all time periods and for all teeth. From T0 to T5 an increase in maxillary intercanine width and maxillary retention had an effect on changes in canine wear. Incisal wear was associated with an increase in upper intercanine width (T1–T5). For both arches, an increase in maxillary intercanine width during treatment was associated with less progression of canine and incisal wear, but the explained variance was low, 13.4% and 19.3%, respectively. Conclusions. Retention type and, occasionally, an increase in intercanine width influence anterior teeth wear post-treatment. However, the clinical significance and impact of the examined retention methods on occlusal wear are small.

In vitroantimicrobial activity and polyphenolics content of tender and matureEbenopsis ebanoseeds

Ebenopsis ebano seeds are traditionally used as a coffee substitute, but their biological potential has not been validated yet. We evaluated antimicrobial activity of tender and mature seed extracts against the clinically relevant strains Escherichia coli, Salmonella enterica var. thyphimurium, and Candida albicans, and determined the phenolics present in the extracts. Treatment groups included raw tender seeds (T1), cooked tender seeds (T2), raw mature seeds (T3), toasted mature seeds (T4), and commercially available mature seeds (T5). We observed significant (p < 0.05) growth inhibition of aqueous extracts vs. E. coli (up to 32%) and vs. S. enterica (up to 25%). Similarly, significant (p < 0.05) growth inhibition of methanol extracts vs. E. coli (up to 30%), vs. S. enterica (up to 20%), and vs. C. albicans (up to 84%) were observed. In addition, we observed differential levels of gallic acid, cafeic acid, and quercetin in aqueous and methanol E. ebano seed extracts, which varied within the treatments (T1–T5). Commercially available seeds (T5) were observed to possess the highest amount of polyphenolics. Differences in polyphenolic levels observed in the treatment groups were not related to the antimicrobial activity or maturity state of the seeds.

Evaluation of an uncalibrated arterial pulse contour cardiac output monitoring system in cirrhotic patients undergoing liver surgery

BackgroundThe pulmonary artery catheter is invasive and may cause serious complications. A safe method of cardiac output (CO) measurement is needed. We have assessed the accuracy and reliability of a recently marketed self-calibrating arterial pulse contour CO monitoring system (FloTrac/Vigileo™) in end-stage liver failure patients undergoing liver transplant. The pattern of alterations known as cirrhotic cardiomyopathy, and the transplant procedure itself, provided an evaluation under varying clinical conditions. MethodsThe cardiac index was measured simultaneously by thermodilution (CITD: mean of four readings) using a pulmonary artery catheter and pulse contour analysis (CIV: mean value computed by the FloTrac/Vigileo™ over the same time period). Readings were made at 10 time-points during liver transplant surgery (T1–T5) and on the intensive care unit (T6–T10). CIV was computed using the latest Vigileo software version 01.10. ResultsA total of 290 paired readings from 29 patients were collected. Mean (sd) CITD was 5.2 (1.3) and CIV was 3.9 (0.9) litre min−1 m−2, with a corrected for repeated measures bias between readings of 1.3 (0.2) litre min−1 m−2 and 95% limits of agreement of −1.5 (0.2) to 4.1 (0.3) litre min−1 m−2. The percentage error (2sdBias/meanCITD) was 54%, which exceeded a 30% limit of acceptance. Low peripheral resistance and increasing bias were related (r=0.69; P<0.001). The Vigileo system failed to reliably trend CI data, with a concordance compared with thermodilution below an acceptable level (at best 68% of sequential readings). ConclusionsIn cirrhotic patients with hyperdynamic circulation, the Vigileo system showed a degree of error and unreliability higher than that considered acceptable for clinical purposes.

Self-assembly of porphyrin–azulene–porphyrin and porphyrin–azulene conjugates

In this paper we report the synthesis and self-assembling behavior of new porphyrin-azulene-porphyrin and porphyrin-azulene conjugates. The porphyrin-azulene-porphyrin conjugate gelates a number of organic solvents, while the porphyrin-azulene conjugates form vesicles in a chloroform-methanol binary mixture. The structures of the organogels and vesicles have been characterized by SEM and AFM. Two porphyrin-naphthalene-porphyrin and porphyrin-naphthalene conjugates were also prepared. A comparison of their properties with those of the azulene analogues reveals that the intermolecular dipole-dipole interaction of the azulene units plays an important role in promoting the self-assembly of the porphyrin-azulene-porphyrin and porphyrin-azulene conjugates.

Is ‘ideal’ sitting posture real?: Measurement of spinal curves in four sitting postures

There is a lack of quantitative evidence for spinal postures that are advocated as ‘ideal’ in clinical ergonomics for sitting. This study quantified surface spinal curves and examined whether subjects could imitate clinically ‘ideal’ directions of spinal curve at thoraco-lumbar and lumbar regions: (i) flat – at both regions (ii) long lordosis – lordotic at both regions (iii) short lordosis – thoracic kyphosis and lumbar lordosis. Ten healthy male subjects had 3-D motion sensors adhered to the skin so that sagittal spinal curves were represented by angles at thoracic (lines between T1–T5 and T5–T10), thoraco-lumbar (T5–T10 and T10–L3) and lumbar regions (T10–L3 and L3–S2). Subjects attempted to imitate pictures of spinal curves for the flat, long lordosis, short lordosis and a slumped posture, and were then given feedback/manual facilitation to achieve the postures. Repeated measures analysis of variance was used to compare spinal angles between posture and facilitation conditions. Results show that although subjects imitated postures with the same curve direction at thoraco-lumbar and lumbar regions ( slumped, flat or long lordosis), they required feedback/manual facilitation to differentiate the regional curves for the short lordosis posture. Further study is needed to determine whether the clinically proposed ‘ideal’ postures provide clinical advantages.

Integrated nutrient management for environmental-friendly rice production in salt-affected rice paddy fields of Saemangeum reclaimed land of South Korea

This study was conducted in an attempt to determine the proper nitrogen and phosphorus application levels, nitrogen split application ratio, and application method for environmental-friendly rice production in a salt-affected rice paddy field, which was located in the Saemangeum reclaimed tidal belt on the western coast of South Korea, between April 1, 2003 and October 10, 2004. All treatments were replicated three times in a randomized block design (5 m × 4 m plot) with 11 treatments (total 33 plots). We designed three treatments for the evaluation of reasonable application levels of nitrogen and phosphorus fertilizers (A1–A3); five treatments to evaluate the nitrogen split application system (T1–T5); and three treatments to determine the proper application for chemical fertilizer (M1–M3). There was no significant difference of amylose and protein content among the application levels, application methods, and nitrogen split application ratios (P < 0.05). No significant differences in grain yield and yield components of rice were observed among the different application levels, application methods, and nitrogen split application ratios (P < 0.05). In order to save labor in agricultural households, preserve or enhance the grain quality of rice, and reduce nutrient losses, we determined that the optimum application level of nitrogen fertilizer was 140 kg ha−1; the application split ratio of nitrogen fertilizer at four different periods was 40% for basal fertilization, 20% for maximum tilling stage, 30% for the panicle formation stage, and 10% for the booting stage; and the best application methods were deep layer application and whole layer application.

Performance de associações de herbicidas em cana-de-açúcar (Saccharum officinarum)

A presente pesquisa teve como objetivo avaliar a seletividade e a eficácia de associações de herbicidas na cultura da cana-de-açúcar variedade RB 83-5486. Para tanto, foram instalados quatro ensaios de pesquisa, sendo dois localizados no município de Nova Londrina, PR, e dois em Marilena, PR. O delineamento experimental utilizado foi o de blocos casualizados, com nove tratamentos e quatro repetições. Em todos os ensaios, os tratamentos foram aplicados em pré-emergência da cana-de-açúcar e das plantas daninhas, a saber: T1 (tebuthiuron) + (hexazinone + diuron), T2 (clomazone + ametrina) + (clomazone), T3 (clomazone + ametrina), T4 (trifloxysulfuron sodium + ametrina), T5 (trifloxysulfuron sodium + ametrina) + (hexazinone + diuron), T6 (clomazone + ametrina) + (hexazinone + diuron), T7 (hexazinone + diuron) + (clomazone), além das testemunhas sem aplicação de herbicidas (T8 - capinada e T9 - sem capina). A maioria dos tratamentos causou leves sintomas de fitotoxicidade na cultura. No entanto, em todos os ensaios, foram observados que aos 100 dias após a aplicação (DAA) as plantas de cana-de-açúcar se recuperaram desses sintomas de fitotoxicidade. Em Nova Londrina, T1 e T7 foram os tratamentos que atingiram controle total de plantas daninhas até aos 100 DAA. Do mesmo modo, os tratamentos T5 e T6 se destacaram no controle das plantas daninhas em Marilena. Nas duas localidades, a biomassa seca da parte aérea da cultura obtida aos 150 DAA nas parcelas tratadas com os herbicidas, não apresentou diferenças significativas em relação à testemunha capinada. Já a interferência das plantas daninhas proporcionou reduções no desenvolvimento da cultura, que variam de 49,9% e 56,2%, respectivamente para as áreas de Nova Londrina e Marilena.

Coronary artery occlusion alters expression of substance P and its mRNA in spinal dorsal horn in rats

The painful sensation during acute myocardial ischemia or infarction is a common symptom and results from neural activity in humans. Little is known about the role of neuropeptides in this effect of myocardial ischemia. The aim of the current study was to investigate the role of substance P in mediating the noxious neural signals in spinal cord in acute myocardial ischemia by exploring the change in substance P and its mRNA in thoracic dorsal root ganglia and spinal dorsal horn (T1–T5) after coronary artery occlusion. The experiment was performed with immunohistochemistry, enzyme immunoassay and real time reverse transcription–polymerase chain reaction techniques on rats’ hearts. In acute myocardial ischemia (<6 h), substance P and preprotachykinin mRNA were up-regulated in the neurons of the dorsal root ganglia and spinal dorsal horn. The increase in the density of immunoreactive material was mainly observed in small-diameter neurons of the dorsal root ganglia and the superficial laminae (I and II) of the spinal cord. The increase in the expressions was statistically significant compared with the control and the sham surgery groups ( P<0.05). The results suggest that substance P is involved in the mediation of the noxious neural signals of acute myocardial ischemia in spinal cord. The pathophysiological role and significance need to be investigated.

Activation of Coagulation During Hemodialysis: Effect of Blood Lines Alone and Whole Extracorporeal Circuit

Activation of coagulation during hemodialysis (HD) is a relevant clinical problem, especially when patients at risk of bleeding are treated. However, little is known about the relative contribution of the various components of the circuit to the thrombotic process. Thus, an experimental model was developed that is aimed at evaluating biochemical markers of coagulation activation at different times and sites throughout the HD circuit. A HD blood-tubing set with integrated arterial and venous chambers (cartridge-line set) was used, which was added with the following sampling points: at the beginning of the arterial line (P1), before the blood pump (P2), after the blood pump (P3), and at the end of the venous line (P4). A bypass system allowed us to circulate the blood only into the blood lines for the first 20 min of the extracorporeal circulation. The extracorporeal circuit was rinsed with 1.7 L of heparinized saline (2,500 IU/L) that was completely discarded before patient connection. A continuous administration of unfractionated heparin (500-800 IU/h) without a starting bolus was adopted as a low heparin extracorporeal treatment. Samples were collected before the start of the extracorporeal circulation from the fistula needle (T0P0), after 5 (T1), 10 (T2), and 20 min (T3) from P1, P2, P3, and P4. After 20 min, the blood was returned to the patient using only saline and HD was then started, circulating the blood through the dialyzer. Further samples were obtained from P1 and P4 after 5 (T4) and 210 min (T5). Plasma levels of coagulation activation markers-thrombin-antithrombin complex (TAT) and prothrombin fragment 1 + 2 (F1 + 2)-were evaluated in all the samples in 12 stable HD patients. In each patient, the activated partial thromboplastin time (APTT) was measured at T0P0 and T1-T5 from P1. No significant changes were found at any time as far as F1 + 2 is concerned. However, TAT levels increased over time only after the start of HD, suggesting that the latter test could be more useful in order to detect coagulation activation during HD. The same experiments performed with nonheparin-primed extracorporeal circuit showed similar results. The blood lines used did not significantly activate coagulation during the first 20 min, whereas only 5 min of blood circulation throughout the whole circuit increased TAT values, which still remained lower than previous reports, even after 210 min of treatment.

Biomechanical changes after the augmentation of experimental osteoporotic vertebral compression fractures in the cadaveric thoracic spine

Background context Osteoporotic compression fractures are an important public health concern, leading to significant morbidity, mortality and economic burden. Cement augmentation procedures used to treat these fractures alter the biomechanics of the fractured segment, which could promote adjacent failure. However, if alignment is improved or restored, there will be less risk of adjacent failure. Purpose To determine the effects of load (compression/flexion), adjacent vertebral location (superior/inferior) and augmentation on vertebral segment stiffness and adjacent vertebral strain in the upper and lower thoracic spine. Study design Human cadaveric thoracic spine segments were tested under load control before and after the creation of experimentally augmented vertebral compression fractures. Methods Six T1–T5 and six T8–T12 segments were obtained from eight thoracic spines with known bone mineral density (BMD). Rosette strain gauges were applied to T2, T4, T9 and T11 to measure strain adjacent to the experimental fracture sites T3 and T10. Two compression fractures were created in succession, the first in flexion preceded by a weakening defect in T3 and T10 and the second created in an adjacent vertebra in compression without prior weakening. The first fracture was reduced with the inflatable bone tamp (IBT) and augmented with cement. Compression and flexion tests were performed before and after the first fracture while measuring vertebral cortical shear strain on T2, T4, T9 and T11 and stiffness of the entire segment. Strain and stiffness were compared by using a repeated measures analysis using adjacent vertebral location (superior/inferior), augmentation and load (compression/flexion) as factors. Results The mean BMD was 0.61±0.11 g/cm 2 (T1–T5) and 0.78±0.07 g/cm 2 (T8–T12). Stiffness in compression and flexion increased with load (p<.05, and p>.27, respectively). Augmentation reduced compressive and bending stiffness (p=.23, and p=.19, respectively), whereas the adjacent vertebral strain increased (p>.11). The adjacent strain in flexion was much greater than in compression (p<.03). Cement augmentation caused greater amounts of inferior than superior adjacent strain (p>.19). The applied moment at first fracture was 2.98±1.28 Nm (T1–T5) and 8.44±1.02 Nm (T8–T12). The compressive load at second fracture was 1122±993 N (T1–T5) and 2906±1008 N (T8–T12). Adjacent vertebral strain during the second compression and flexion tests exceeded that during the first compression and flexion tests (p=.11). Adjacent vertebral strain at second fracture exceeded that at first fracture (p=.007) and was greater on the superior adjacent vertebra than the inferior (p=.47). Conclusion With axial compressive loads, the addition of flexion increases fracture risk. Cement augmentation of a fractured vertebral segment reduces stiffness while increasing both the superior and inferior adjacent cortical strain. This increment in strain that is greatest on the inferior adjacent vertebra effectively redistributes loads from the superior adjacent vertebra to the inferior adjacent vertebra, sparing the superior adjacent vertebra from failure.

Pudendal nerve block for pain relief in episiotomy repair

Injection of local anesthetic in the line of episiotomy incision is the generally used method for pain relief during reconstruction. There is no study comparing different methods regarding the pain relief during the episiotomy repair. We aimed to compare the efficacy of pudendal nerve block and local infiltration of 2% prilocaine in the relief of pain during episiotomy repair. Ninety pregnant women at the beginning of the first stage of labor were enrolled into this study. Group A (n=45) received conventional local infiltration of 5 ml 2% prilocaine in the line of the proposed incision of mediolateral episiotomy. Unilateral pudendal block was performed in patients Group B (n=45) with injection of 5 ml 2% prilocaine over the pudendal nerve with the help of a tubular director. Seven patients were excluded from the study with the diagnosis of pudendal nerve block failure (15.5%). All women were asked by a nurse who was blinded to patient group in order to rate the intensity of pain on a visual analog scale (VAS) of 100 mm at different stages of the procedure (T1–T5). (excerpt)

Plasma catecholamine and cardiovascular reactivity during an acute high ropes course event

The primary purpose of this study was to describe physiological responses to an acute high ropes course stress. The selected dependent variables were epinephrine (E), norepinephrine (NE), heart rate (HR), systolic/diastolic blood pressure (BPs and BPd) and self-reported anxiety. A secondary purpose was to explore possible relationships between the observed physiological responses and physical fitness. College-age males were recruited for preliminary V o 2 max testing to identify a high-fit and low-fit subject pool. Eleven were identified as eligible participants and gave informed consent. Six participants were in the high-fit category (V o 2 max>60 ml/kg) and five in the low-fit category (V o 2 max<42 ml/kg). The Power Pole, a common high ropes course event, was selected as the acute field-based challenge activity. During participation in the challenge, a series of five (T1–T5) 10-ml blood samples were taken (via intravenous catheter) to be analyzed for E and NE. Subjective anxiety, HR, BPs and BPd were also measured at T1–T5. When the data were analyzed in a 2 (fitness group)×5 (time) factorial ANOVA, there was a significant main effect for time with each dependent variable. However, the only difference between fitness levels was found with HR. These results indicate that the Power Pole is an acute field-based stressor for individuals of both high and low fitness levels. Due to the lack of difference between fitness groups for all variables other than HR, we conclude that participating in the Power Pole event elicits more stress of a psychosocial nature than stress of physical exertion.

Flexural strength of Cerec 2 machined and jointed InCeram-Alumina and InCeram-Zirconia bars

Objective. The flexural strength of Cerec 2 InCeram-Alumina and InCeram-Zirconia bars is evaluated. The focus of the in vitro study is to identify a jointing procedure for InCeram which may be used for producing full-ceramic fixed-partial-denture frameworks. Methods. Six groups ( n=15) of machined and jointed InCeram-Alumina (T1–T5) and InCeram-Zirconia (T6) bars (3×4×13 mm 3), respectively, were examined using a 3-point-bending test. InCeram-Alumina joint-free controls were: machined (C1), slip cast (C2, C3) and cut from the block (C4) bars. Machined joint-free InCeram-Zirconia bars were used as controls (C5). InCeram-Alumina slip was used for jointing T1–T5 and InCeram-Zirconia slip for bars T6. Bars were jointed in groups T1 and T2 using butt joint (S1), in T3 and T4 oblique (S2, S3) and in T5 and T6 rounded (S4) joint shapes. Results. Two-way analysis of variance showed significant differences between materials ( p<0.001) and jointing shapes ( p<0.001). The rounded (S4) shape showed the highest flexural strength of 434 (65) MPa of InCeram-Alumina (T5) and 475 (54) MPa of InCeram-Zirconia (T6) bars, respectively but machined/joint-free InCeram-Alumina (511 (59) MPa, C1) and machined/joint-free InCeram-Zirconia (624 (58) MPa, C5) were significantly ( p<0.01/ p<0.001) stronger. No significant differences ( p>0.05) were found between machined/jointed InCeram-Zirconia (475 (54) MPa, T6), joint-free InCeram-Alumina slip cast (498 (125) MPa, C2) and joint-free InCeram-Alumina machined bars (511 (59) MPa, C1). Significance. Compared to conventional slip cast InCeram-Alumina the flexural strength of machined/jointed InCeram-Zirconia appears to be adequate for fixed-partial-denture frameworks.

Thoracic pedicle: surgical anatomic evaluation and relations.

This anatomic study investigated the thoracic pedicle and its relations. The objective was to emphasize the importance of the thoracic pedicle for transpedicular screw fixation to avoid complications during surgery. Twenty cadavers were used to observe the cervical pedicle and its relations. The isthmus of the pedicle was exposed after removal of whole-posterior bony elements, including spinous processes, laminas, lateral masses, and the inferior and superior facets. The pedicle width and height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, root exit angle, and nerve root diameter were measured. There was no distance between the pedicle and dural sac in eight specimens. There was, however, a short distance in 12 remaining specimens in the upper and lower thoracic regions. The distances between the thoracic pedicle and the adjacent nerve roots ranged from 1.5 to 6.7 mm and 0.8 to 6.0 mm superiorly and inferiorly at all levels. The mean pedicle height and width at T1-T12 ranged from 2.9 to 11.4 mm and 6.2 to 21.3 mm, respectively. The interpedicular distance decreased gradually from T1 to T5 and then increased gradually to T12. The mean root exit angle decreased consistently from 104 degrees to 60 degrees. The nerve root diameter was between 2.3 and 2.5 mm at the T1-T5 level and then increased consistently from 2.5 to 3.7 mm. All significant differences were noted at p < 0.05 and p < 0.01. The following suggestions are made based on these results. 1) More care should be taken when a transpedicular screw is placed in the horizontal plane. 2) Improper medial placement of the pedicle screw, especially in the middle thoracic spine, should be avoided, and the anatomic variations between individuals should be considered. 3) Because of substantial variations in the size of thoracic pedicles, utmost attention should be given to the findings of a computed tomographic evaluation before thoracic transpedicular fixation is begun.

Gastric tonometer monitoring in infants undergoing repair of coarctation of the aorta

Objective: To evaluate gastric tonometer monitoring for splanchnic hypoperfusion in infants during surgical intervention for aortic coarctation, especially within aortic cross-clamp periods. Design: A prospective study. Setting: Cardiovascular intensive care unit in a university hospital. Participants: Fourteen infant patients after elective, uncomplicated repair of coarctation of the aorta. Interventions: After the anesthesia induction, a 7F tonometry catheter was inserted into the stomach oropharyngeally. Gastric carbon dioxide, arterial blood gases, blood pressure of upper extremities, and hematocrit values were measured in 5 different time intervals. Time periods were as follows: T1 (after the anesthesia induction), T2 (before aortic cross-clamp), T3 (immediately after aortic cross-clamp removal), T4 (40 minutes after aortic cross-clamp removal), and T5 (as the patient reached the intensive care unit). Intramucosal pH was measured by means of the Henderson-Hasselbach equation. The mean values of all parameters were calculated. According to T1 time, T2, T3, T4, and T5 times were compared with Student's t-test. Measurements and Main Results: Mean aortic cross-clamp time was 19.4 ± 6.6 minutes. Intramucosal pH values of T3 (p < 0.001) and T4 (p < 0.01) were found to be lower than values of T1. The gastric carbon dioxide values of T3 were significantly higher than T1 (p < 0.01), and bicarbonate and arterial pH values of T3 were significantly lower (p < 0.01). There were no significant differences in other parameters over time intervals. Conclusion: Splanchnic hypoperfusion exists during aortic cross-clamping in infant aortic coarctation surgery, and the tonometric catheter is considered to be a safe method for monitoring this hypoperfusion. Copyright © 2000 by W.B. Saunders Company

Measurement of Sympathetic Blockade: Effect of Epidural and Spinal Anesthesia

Consultant in Anesthesiology Akureyri Central HospitalAkureyri, IcelandDirectorklaus.kirno@medfak.gu.seProfessorDepartment of Cardiothoracic Anesthesiology and Intensive CareAssociate ProfessorDepartment of Clinical NeurophysiologySahlgrenska University HospitalUniversity of GöteborgGöteborg, SwedenIn Reply:—We appreciate the interest and comments expressed by Drs. Introna, Blair, Martin, and Yodlowski. We fully agree that indirect methods of measuring sympathetic nerve activity can provide useful, qualitative information. Quantification of sympathetic nerve activity, however, is difficult with these techniques.The main issue raised by Introna et al. is whether a high thoracic epidural anesthesia (TEA) completely inhibits cardiac sympathetic activity. Based on studies measuring heart rate variability, these authors are convinced that TEA with T1–T5 sensory blockade does not result in complete cardiac sympathetic blockade. However, a comparative study of heart rate variability, cardiac norepinephrine spillover, and muscle sympathetic nerve activity in humans by Kingwell et al. 1invites some caution because it showed heart rate variability to be dependent on multiple factors in addition to cardiac sympathetic nerve activity and not directly related to cardiac norepinephrine spillover.The degree of thoracic sympathetic blockade was not specifically addressed in our recent study, 2which was primarily aimed at evaluating sympathetic function caudal to the TEA-induced sensory blockade and showed no sign of sympathetic blockade. However, previous microneurographic studies of lumbar epidural and spinal anesthesia have shown a fairly close relation between the extent of sensory and sympathetic blockade. 3,4Because the nerves to internal organs are not accessible to microneurographic recording in humans, we previously used biochemical measurements of nerve transmitter release to quantify cardiac sympathetic nerve activity. 5We used an isotope dilution technique with radiolabeled norepinephrine to demonstrate that TEA prevented the sympathetically mediated surgical stress response during coronary artery bypass surgery. Although this finding could be explained by an afferent nociceptive blockade or an efferent blockade of cardiac sympathetic nerve fibers, supportive evidence for the existence of a cardiac sympathetic blockade after TEA has been provided by Taniguchi et al. , 6who directly measured efferent cardiac sympathetic nerve activity after TEA in an experimental study on cats. Our recent finding 2that vasomotor and sudomotor reflexes were abolished in the hands but remained in the feet after TEA also suggests a thoracic sympathetic blockade. Therefore, although we agree with Introna et al. that “sympathetic fibers above and below the segment of epidural anesthesia could travel cephalad or caudad within the sympathetic chain” and “continue to innervate the heart,” we remain convinced that TEA can abolish sympathetic reflexes within thoracic segments.

Evaluation of scraping treatments to restore initial infiltration capacity of three artificial recharge projects in central Iran

A limiting factor in developing artificial recharge of groundwater is clogging of the soil surface and consequent reduction of infiltration rates. In order to evaluate the degree of improving infiltration rates by scraping away various amounts of the upper soil materials, a study was conducted at three artificial recharge sites (Kohrouyeh, Bagh-Sorkh, and Kachak) in Isfahan Province, central Iran. Five treatments (T1–T5) were considered. Infiltration was measured: T1, on deposited sediment layer; T2, after removing the sediments; T3, scraping of sediments and 5 cm of soil; T4, scraping of sediments and 10 cm of soil; and T5, removing sediments and 15 cm of soil. Initial soil-moisture content of the sites ranged from 1.0–2.87% for Kohrouyeh, 1.18–3.47% for Bagh-Sorkh, and 1.89–3.93% for Kachak. The main texture of the soils was sandy loam. Clay particles have penetrated to a depth of more than 40 cm in some of the recharge basins. A significant increase in final infiltration rate of T5 as compared to T1 treatment was observed for all recharge sites. The final infiltration rates of T1 and T5 treatments for Kohrouyeh, Bagh-Sorkh, and Kachak sites were 0.35, 7.9; 1.22, 12.3; and 0.93, 6.2 cm/h, respectively. The differences between infiltration rates of T2, T3, and T4 treatments were not statistically significant. It is concluded that on average, the infiltration capacity of the untreated recharge facilities have reached 20.3% of the original values, and that scraping the top sediment layer and 15 cm of topsoil could restore 68.3% of the initial infiltration capacity.

Grain orientation effects in Zr702 α polycrystalline samples deformed in channel die compression at room temperature

Deformation mechanisms are determined in five zirconium polycrystalline samples deformed by channel die compression at room temperature (T1–T5 textures). Slip systems are characterized by a slip trace analysis and twinning systems by a misorientation calculation between twinned and non-twinned parts of the grains, from Electron Back Scattering Diffraction (EBSD) measurements. The analysis is completed by the measurement of crystallographic texture evolutions and the examination of the stress–strain curves. Prismatic glide and {10 12} twinning are identified as primary deformation modes and first-order pyramidal slip {10 11} and basal slip as secondary slip modes. The experimental study is completed by a numerical approach using polycrystalline models which is consistent with the experimental observations.

Evidence of a direct projection from the cardiovascular-reactive dorsal medulla to the intermediolateral cell column of the spinal cord in cats as revealed by light and electron microscopy

To ascertain whether the dorsal medulla, a well-established vasopressor structure, would project directly to the sympathetic intermediolateral cell column of the spinal cord, we have carried out both anterograde and retrograde tracing studies in cats. For anterograde tracing, biotin–dextran was iontophoretically delivered into the cardiovascular-reactive dorsal medulla following its functional identification by electrical stimulation. The anterogradely transported biotin–dextran was then visualized using the avidin–biotin–horseradish peroxidase complex method. By light microscopy, dextran-labelled varicose axons were observed bilaterally in the intermediolateral nucleus extending from segments T1 to L3, but concentrated in segments T1–T5, notably at levels T2–T4. Electron microscopic examination revealed the localization of biotin–dextran reaction product in some small myelinated axons and axon terminals in the intermediolateral cell column. The majority of tracer-labelled axonal boutons contained spherical synaptic vesicles and made asymmetric synaptic contacts primarily with small dendrites. A few boutons contained polymorphic synaptic vesicles and tended to form symmetric axodendritic synapses. Spinally projecting neurons of the dorsal medulla were identified using the retrograde transport of horseradish peroxidase injected into the electrically cardiovascular-reactive intermediolateral nucleus. The labelled neurons were localized in the medullary dorsomedial reticular formation ventromedial to the nucleus of the solitary tract, approximately 0.5–5 mm rostral to the obex. The projection was bilateral, but was relatively denser in the rostral portion of the contralateral dorsal medulla. The present findings support the hypothesis that the dorsal medulla, through its direct pathway innervating the intermediolateral nucleus, may serve as a sympathetic premotor structure for regulation of arterial pressure.