Hours Of Blood Sampling Research Articles

Relationships between renal function variations and relative changes in cardiac troponin T concentrations based on quantile generalized additive models (qgam).

The relationship between high-sensitive cardiac troponin T concentration (hs-cTnT) and renal markers levels is known. However, the extent to which their variations are associated remains to be explored. Objective: model the relationship between relative changes in hs-cTnT (Δhs-cTnT) and variations in creatinine (Δcre) or estimated glomerular filtration rate (ΔeGFR), using a quantile generalized additive model (qgam). Concomitant plasma Δhs-cTnT and Δcre from patients aged 18-100 years, selected with a time variation (Δtime) of 3h-7days, were collected over a 5.8-year period. Relationships between Δhs-cTnT and covariates Δcre (A)or ΔeGFR (B), including age, Δtime, hour of blood sampling (HSB) and covariates interactions were fitted using qgam. On the whole (n=106567), Δhs-cTnT was mainly associated with Δcre, in a positive and nonlinear way (-21,-6, +5, +20, +55% for-50,-20, +20, +50, +100%, respectively), but to a lesser extent with age (min-9%, max +2%), Δtime (min-4%, max +8%), and HSB (min-5%, max +7%). Δhs-cTnT was negatively associated with ΔeGFR (+46, +7,-5,-11,-20% for-50,-20, +20, +50, +100%, respectively). Classifying Δhs-cTnT as consistent or not with myocardial injury based on recommendations, an interpretation of Δhs-cTnT adjusted for model A or B led to statistically significant but small diagnostic discrepancies (<2%), as compared to an interpretation based on Δhs-cTnT only. From a laboratory and statistical standpoint, considering renal function variations when interpreting relative changes in cardiac troponin T has a minor impact on the diagnosis rate of myocardial injury.

Antibody Microarray Analysis of Plasma Proteins for the Prediction of Histologic Chorioamnionitis in Women With Preterm Premature Rupture of Membranes

We aimed to identify maternal blood biomarkers predictive of histologic chorioamnionitis (HCA) in the plasma of women with preterm premature rupture of membranes (PPROM) and to determine whether the combination of these biomarkers with conventional clinical variables can improve the prediction of HCA. This retrospective cohort study included 82 consecutive women with PPROM (23-34 gestational weeks) who delivered within 96 hours of blood sampling. A membrane-based human antibody microarray was used to analyze the plasma proteome. The validation of 5 candidate biomarkers of interest was performed by enzyme-linked immunosorbent assay (ELISA) in the final cohort (n = 82). Serum C-reactive protein (CRP) levels were measured at sampling. Seventy-nine molecules studied exhibited intergroup differences. Validation by ELISA confirmed higher levels of plasma matrix metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), S100 A8/A9, and insulin-like growth factor-binding protein 1 (IGFBP-1), but not tissue inhibitor of metalloproteinase 1 (TIMP-1), in women with HCA than in women without HCA. Using a stepwise regression analysis, a combined prediction model was developed, which included the plasma MMP-9, serum CRP levels, and gestational age (area under the curve [AUC], 0.932). The AUC for this model was significantly greater than that for any single variable included in the predictive model. Protein-antibody microarray technology can be useful in identifying plasma-based predictors for HCA. This study suggests that plasma MMP-9, IL-6, IGFBP-1, and S100 A8/A9 are important noninvasive predictors for HCA in women with PPROM and that the best predictive model, which combined these biomarkers with conventional clinical factors, can significantly improve the predictability for HCA.

A Single-Dose of a Polyphenol-Rich Fucus Vesiculosus Extract is Insufficient to Blunt the Elevated Postprandial Blood Glucose Responses Exhibited by Healthy Adults in the Evening: A Randomised Crossover Trial.

When healthy adults consume carbohydrates at night, postprandial blood glucose responses are elevated and prolonged compared to daytime.Extended postprandial hyperglycaemia is a risk factor for type 2 diabetes. Polyphenols are bioactive secondary metabolites of plants and algae with potential to moderate postprandial glycaemia. This study investigated whether a polyphenol-rich alga (Fucus vesiculosus) extract moderated postprandial glycaemia in the evening in healthy adults. In a double blind, placebo-controlled, randomised three-way crossover trial, 18 participants consumed a polyphenol-rich extract, a cellulose placebo and rice flour placebo (7:15 p.m.) prior to 50 g available carbohydrate from bread (7:45 p.m.), followed by three hours of blood sampling to assess glucose and insulin. A subset of participants (n = 8) completed the same protocol once in the morning with only the cellulose placebo (7:15 a.m.). No effect of the polyphenol-rich extract was observed on postprandial glycaemia in the evening, compared with placebos, in the group as a whole. However, in females only, peak blood glucose concentration was reduced following the polyphenol-rich extract. In the subset analysis, as expected, participants exhibited elevated postprandial blood glucose in the evening compared with the morning following the cellulose placebo. This was the first study to investigate whether a polyphenol intervention moderated evening postprandial hyperglycaemia. The lowering effect observed in females suggests that this warrants further investigation.

Feedback on LH in Testosterone-Clamped Men Depends on the Mode of Testosterone Administration and Body Composition.

ContextQuantitative studies of the short-term feedback of testosterone (T) on luteinizing hormone (LH) secretion in healthy men are relatively rare. Such studies require the shutting down of endogenous T secretion and the imposition of experimentally controlled IV T addback.ObjectiveTo evaluate whether pulsatile and continuous T delivery confers equivalent negative feedback on LH secretion.DesignThis was a placebo-controlled, blinded, and prospectively randomized crossover study comprising 16 healthy men [age range 23 to 54 years and a body mass index (BMI) between 22.3 and 34.2 kg/m2]. Subjects received ketoconazole to block endogenous T secretion and received continuous or 90-minute pulses of IV T addback.SettingThe study was performed in a Clinical Translational Research Unit.InterventionsSubjects underwent 14 hours of blood sampling at 10-minute intervals, with a bolus IV injection of 33 ng/kg gonadotropin-releasing hormone (GnRH).Main Outcome MeasuresLog-transformed LH and T concentration ratios before and after GnRH administration.ResultsDespite higher T concentrations during pulsatile T feedback, LH concentrations and secretion rates, whether driven by endogenous or exogenous GnRH, were similar to those during continuous T infusion, indicating diminished pulsatile T feedback. Feedback correlated negatively with BMI. Under controlled T feedback, basal but not pulsatile LH secretion correlated negatively with CT-estimated visceral fat mass.ConclusionFeedback by pulsatile T delivery has diminished inhibitory strength compared with continuous infusion. Feedback is negatively correlated with BMI.

Candidemia in non-ICU surgical wards: Comparison with medical wards.

Candidemia acquired outside critical care or hematological areas has received much attention in recent years; however, data on candidemia in surgical departments are very scarce. Our objectives were to describe episodes of candidemia diagnosed in surgical wards and to compare them with episodes occurring in medical wards. We performed a post hoc analysis of a prospective, multicenter study implemented in Spain during 2010–2011 (CANDIPOP project). Of the 752 episodes of candidemia, 369 (49.1%) occurred in patients admitted to surgical wards (165, 21.9%) or medical wards (204, 27.2%). Clinical characteristics associated with surgical patients were solid tumor as underlying disease, recent surgery, indwelling CVC, and parenteral nutrition. Candidemia was more commonly related to a CVC in the surgical than in the medical wards. The CVC was removed more frequently and early management was more appropriate within 48 hours of blood sampling in the surgical patients. Overall, 30-day mortality in the surgical departments was significantly lower than in medical wards (37.7% vs. 15.8%, p<0.001). Multivariate analysis revealed admission to a surgical ward and appropriate early management of candidemia as factors independently associated with a better outcome. We found that approximately 50% of episodes of candidemia occurred in non-hematological patients outside the ICU and that clinical outcome was better in patients admitted to surgical wards than in those hospitalized in medical wards. These findings can be explained by the lower severity of underlying disease, prompt administration of antifungal therapy, and central venous catheter removal.

Abstract 210: Soluble Tumor Necrosis Factor Receptors, Marker of Arterial Stiffness in Patients With Coronary Atherosclerosis

Background: Soluble forms of tumor necrosis factor receptors (sTNFRs) are emerging target molecules of inflammatory disease. However, their role in vascular biology is not well known. This study was performed to investigate the association between serum concentrations of sTNFRs and arterial stiffness. Methods and Results: A total of 117 consecutive patients with suspected coronary artery disease (CAD) (63.6 ± 11.0 years; men, 65%) who were referred for invasive coronary angiography (ICA) were prospectively enrolled. Arterial blood sTNFR1 and sTNFR2 were measured using commercially available ELISA kits. Brachial-ankle pulse wave velocity (baPWV) measurements were made within 24 hours of blood sampling for sTNFRs measurement. Most of the patients (86.3%) had significant CAD (stenosis ≥ 50%) in ICA. In simple linear regression analyses, there were significant positive correlations of baPWV with sTNFR1 ( β = 0.483, P &lt; 0.001) and sTNFR2 ( β = 0.366, P &lt; 0.001). The baPWV values increased proportionally with increasing sTNFR1 ( P = 0.002) and sTNFR2 ( P = 0.076) tertiles. In multiple linear regression analyses, sTNFR1 ( β = 0.300, P &lt; 0.001) and sTNFR2 ( β = 0.206, P = 0.013) had independent association with baPWV even after controlling for potential confounders including age, gender, systolic blood pressure, diabetes mellitus and hypertension. Conclusions: Taken together, sTNFR1 and sTNFR2 were independently associated with baPWV in patients undergoing ICA. This study suggests that sTNFR1 and sTNFR2 can be considered therapeutic targets as well as new makers of arterial stiffness.

Soluble Tumor Necrosis Factor Receptors and Arterial Stiffness in Patients With Coronary Atherosclerosis.

Soluble forms of tumor necrosis factor receptors (sTNFRs) are emerging target molecules of inflammatory disease. However, their role in vascular biology is not well known. This study was performed to investigate the association between serum concentrations of sTNFRs and arterial stiffness. A total of 117 consecutive patients with suspected coronary artery disease (CAD) (63.6 ± 11.0 years; men, 65%) who were referred for invasive coronary angiography (ICA) were prospectively enrolled. Arterial blood sTNFR1 and sTNFR2 were measured using commercially available ELISA kits. Brachial-ankle pulse wave velocity (baPWV) measurements were made within 24 hours of blood sampling for sTNFRs measurement. Most of the patients (86.3%) had significant CAD (stenosis ≥ 50%) in ICA. In simple linear regression analyses, there were significant positive correlations of baPWV with sTNFR1 (r = 0.483, P < 0.001) and sTNFR2 (r = 0.366, P < 0.001). In multiple linear regression analyses, sTNFR1 (β = 0.316, P < 0.001) and sTNFR2 (β = 0.235, P = 0.005) had independent association with baPWV even after controlling for potential confounders. sTNFR1 and sTNFR2 were independently associated with baPWV in patients undergoing ICA. This result may extend previous knowledge on close interactions between inflammation and arterial stiffening.

Mean Platelet Volume and Splenomegaly as Useful Markers of Subclinical Activity in Egyptian Children with Familial Mediterranean Fever: A Cross-Sectional Study.

Objective. To study whether mean platelet volume (MPV) and splenomegaly could be used as subclinical inflammatory markers in children with familial Mediterranean fever (FMF) at the attack-free period. Patients and Methods. The study included ninety-seven children with FMF. MPV was carried out within 4 hours of blood sampling according to standard laboratory practice. Splenomegaly was determined by abdominal ultrasound (USG). Results. High MPV was detected in 84.45% of our studied patients and was significantly higher in FMF patients with splenomegaly than in patients without splenomegaly. There was a statistically significant correlation between MPV and splenic span (P = 0.045). Conclusion. Elevated MPV and its significant correlation with splenic span in FMF children during the attack-free periods support the use of MPV and splenomegaly as useful markers of the subclinical inflammation in FMF patients at the attack-free period.

Abstract 4828: Circulating tumor cells (CTCs) isolated from patients with metastatic breast cancer utilizing a sensitive microfluidic graphene oxide (GO) nanosheet device express markers of cancer stem cells

Abstract Breast cancers are driven by a subset of cells that display stem cell properties. These “cancer stem cells” (CSCs) mediate metastasis and contribute to treatment resistance. Many current CTC isolation technologies are limited in their sensitivity and are particularly inefficient at capturing cells which display an epithelial mesenchymal transition (EMT) phenotype which has been associated with CSCs. We have developed a sensitive microfluidic device using functionalized graphene oxide (GO) nanosheets to identify and isolate CTCs from patients with metastatic breast cancer. Unlike other CTC capture devices with microposts, the effective functionalized surface created by GO allows the device to be two-dimensional. The GO nanosheets were adsorbed onto the patterned gold surface and then chemically functionalized. Blood samples were collected into EDTA and AdnaGen tubes from patients with metastatic breast cancer and analyzed within 24 hours of blood sampling. Isolated CTCs were studied for expression of genes using a multiplex TaqMan-based qRT-PCR method. CTC preparations were checked for white blood cells (WBCs) contamination by examining CD45 expression and verifying that there was no or extremely low levels of CD45 expression in all of the processed samples. The majority of isolated CTCs showed mRNA expression of EMT markers including TGFβ and Vimentin at different levels among tested samples. In addition, markers of breast CSCs including CD44+/CD24- and ALDH1+ were observed in CTCs isolated from patients across the molecular subtypes of breast cancer. Interestingly, HER2+ CTCs were isolated from patients with HER2/neu- primary tumors. This is consistent with recent work from our group that demonstrated selective expression of HER2 in the CSC-like populations of luminal breast cancers occur independent of HER2 gene amplification. These studies demonstrate the feasibility of utilizing GO nanosheet microfluidic devices to isolate and molecularly characterize CTCs from metastatic breast cancer patients. Such liquid biopsies may be of particular value for following CSC populations for patients on therapeutic clinical trials. Citation Format: Shamileh Fouladdel, Hyeun Joong Yoon, Tae Hyun Kim, An Shi, Tahra Luther, Jill Hayden, Shawn G. Clouthier, Yadwinder S. Deol, Monika L. Burness, Daniel F. Hayes, Sunitha Nagrath, Ebrahim Azizi, Max S. Wicha. Circulating tumor cells (CTCs) isolated from patients with metastatic breast cancer utilizing a sensitive microfluidic graphene oxide (GO) nanosheet device express markers of cancer stem cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4828. doi:10.1158/1538-7445.AM2014-4828

Aromatase inhibition causes increased amplitude, but not frequency, of hypothalamic-pituitary output in normal women

To better understand the site and mode of action of aromatase inhibitors. Prospective study. Academic research environment. Five eumenorrheic (without polycystic ovary syndrome), early follicular phase women with a normal body mass index (mean: 20.47±0.68 kg/m2), and 12 normal weight, midreproductive aged, early follicular phase women with a normal body mass index (mean: 20.8±1.7 kg/m2) as historical controls. 2.5 mg letrozole daily for 7 days, with daily urine collection (first morning void), thrice weekly blood sampling, and 4 hours of blood sampling every 10 minutes. Serum luteinizing hormone (LH) measured by a well-characterized immunofluorometric assay with LH pulse characteristics compared between treated and control groups using t tests. Mean LH and LH pulse amplitude more than doubled in the women who had taken letrozole compared with the controls, but the LH pulse frequency did not differ between the women taking letrozole and the controls. These results indicate that the release of negative feedback inhibition of estradiol on the hypothalamic-pituitary axis in normal women by aromatase inhibitors creates an amplitude-related increase in endogenous hypothalamic-pituitary drive. The finding that the mean LH and LH pulse amplitude, but not the frequency, increased after letrozole suggests a possible pituitary site of action.

Nifedipine Pharmacokinetics and Plasma Levels in the Management of Preterm Labor

The aim of this study was to determine if the dose regimen of nifedipine used for tocolysis was effective to achieve uterine quietness, and at which plasma concentration levels this tocolysis was achieved to optimize our dose regimen of nifedipine. In women with preterm labor, nifedipine was administered orally to achieve uterine quietness to prevent preterm birth. Patients (n = 5) were administered 10 mg nifedipine capsules (Adalat capsules, Bayer AG) orally every 15 minutes up to 40 mg in the first hour, and were subsequently given 1 tablet of 20 mg nifedipine slow release (Adalat retard, Bayer AG) t = 90 min. Plasma levels of nifedipine were measured at regular intervals during the first 4 hours after starting tocolysis. In all 5 patients tocolysis was achieved with nifedipine. Peak plasma concentration of nifedipine was 127.2 +/- 44 ng/mL at 1.2 +/- 0.1 hours. Mean plasma concentrations of nifedipine was 67.4 +/- 28.4 ng/mL. In all patients, tocolysis was achieved during the 4 hours of blood sampling. There were no adverse hemodynamic side effects seen before and after starting tocolysis with nifedipine. Initial dose regimen of 4 times 10 mg nifedipine capsule orally in the first hour, followed by 20 mg slow release nifedipine at t = 90 min is effective in achieving tocolysis in women with preterm labor. In steady state, the mean nifedipine plasma concentration to achieve tocolysis is about the half of that measured after initial tocolysis. Use of nifedipine for preterm labor was not associated with any adverse hemodynamic side effects.

Blood Viscosity of the Neonate

After completing this article, readers should be able to: 1. List the determinants of blood viscosity in the neonate. 2. List the causes of polycythemia and hyperviscosity in the neonate. 3. List the signs, symptoms, and diagnostic criteria for polycythemia and hyperviscosity. 4. Describe steps for prevention and treatment of polycythemia and hyperviscosity in the neonate. Blood viscosity is defined as resistance to the movement of blood. In a circular vessel or tube, the resistance (R) increases with increasing viscosity (V) of the moving fluid and with the resistance resulting from the vessel geometry (Z): R=Z · V. Thus, blood viscosity describes the contribution of blood rheologic factors to blood flow resistance. However, blood viscosity depends on several factors, and the importance of these factors differs among various vessels. The major determinants of blood viscosity are the hematocrit, plasma viscosity, red blood cell (RBC) aggregation, RBC deformability, leukocyte properties, vessel diameter, and the shear forces acting on the RBC. (1) The hematocrit generally is assumed to be the most important determinant of blood viscosity. Blood viscosity rises exponentially with increasing hematocrit (Fig. 1). A marked rise in blood viscosity is seen when the hematocrit exceeds 0.65 L/L, which typically is defined as the threshold for hyperviscosity of the blood. However, in narrow arteries and arterioles and in capillaries, the plasma viscosity becomes the dominant determinant of blood viscosity. The fetal hematocrit increases from 0.33 L/L in the 12th week of gestation to 0.45 L/L in the 30th week and 0.50 L/L in the 40th week at term. At birth, the hematocrit may rise markedly as a result of “blood transfusion” from the placenta to the neonate. (2) A postnatal hematocrit of 0.45 to 0.65 L/L is considered normal in the healthy term neonate. Figure 1. Blood viscosity in tubes that have a diameter of 50 …

Using real-time, quantitative PCR for rapid genotyping of the steroid 21-hydroxylase gene in a north Florida population.

The most common cause of congenital adrenal hyperplasia is steroid 21-hydroxylase deficiency. The molecular genetics of this disease are such that genotyping is a potentially useful tool in its diagnosis. An assay was developed using real-time, quantitative PCR to detect deletions of the steroid 21-hydroxylase gene (CYP21A2). This assay was able to detect heterozygous gene deletions with an alpha error rate of less than 5%, with a power greater than 95%. When combined with allele-specific PCR, genotyping for the nine most common mutations can be completed within hours of blood sampling. This technique was used to study subjects with 21-hydroxylase deficiency in North Florida. Twenty-eight subjects with congenital adrenal hyperplasia, seven first-degree relatives and thirteen normal subjects, were characterized. Of 96 chromosomes, 69 abnormal alleles were identified. Among unrelated abnormal alleles, the frequency of specific mutations was 28% for a gene deletion, 24% for the intron 2 splice mutation, 10% for ile172asn, 8% each for val281leu and the exon 6 cluster, and 6% for gln318x mutations. These frequencies, as well as the genotype/phenotype correlation, were similar to those found in comparable populations. The utility of genotyping in the diagnosis of 21-hydroxylase deficiency is increased by the rapidity of the analysis. With quantitative PCR, the need for more expensive and time consuming Southern blot analysis is reduced and limited to the clarification of certain genotypes. Faster results will allow for more timely initiation of appropriate therapy and limit the exposure of potentially unnecessary therapy.

Effect of smoking on lipid and thrombogenic factors two months after acute myocardial infarction

Cigarette smoking is linked to increased cardiac morbidity and mortality, and has been shown to affect both lipid profiles and thrombotic factors in healthy subjects. However, the influence of smoking on the atherothrombotic environment has not been studied in a large population of patients after acute myocardial infarction (AMI). Blood samples and medical history, including smoking status, were obtained from 1,045 patients at a 2-month visit after AMI. Smokers were asked to refrain 24 hours before the visit, but not all complied. Measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoprotein-B, apolipoprotein-A, triglycerides, factor VII, factor VIIa, von Willebrand factor, D-dimer, and plasminogen activator inhibitor. There were 247 current, 443 past, and 349 nonsmokers. After adjustment for clinical variables, current smokers had higher levels of total cholesterol and apolipoprotein-B than past and nonsmokers (p <0.01). High-density lipoprotein cholesterol and apolipoprotein-A levels were similar between groups. Fibrinogen was elevated in current (p = 0.001) and past (p = 0.029) smokers, compared with nonsmokers. Smokers who smoked within 24 hours of blood sampling had higher apolipoprotein-B (p = 0.005), total cholesterol (p = 0.001), and fibrinogen (p = 0.015) levels than those who refrained from smoking. In conclusion, postinfarction patients, who historically have higher levels of atherogenic lipids than healthy subjects, have increased levels of these lipids attributed to active smoking. After smoking cessation, lipid profiles approach nonsmoker levels, but fibrinogen remains elevated. Smoking within 24 hours of blood sampling was associated with further adverse prothrombotic and lipogenic effects.

Reproducibility of plasma angiotensin-converting enzyme activity in human subjects determined by fluorimetry with Z-phenylalanine-histidyl-leucine as substrate

Despite the major physiologic role of angiotensin-converting enzyme (ACE), few studies have evaluated the ideal conditions for measuring human plasma ACE activity, specifically when using Z-phenylalanine-histidyl-leucine as substrate. This study, performed in volunteer patients, assessed the reproducibility of human plasma ACE activity measured by fluorimetry with Z-phenyl-histidyl-leucine as the substrate. After blood centrifugation, plasma was stored under different conditions until processing. The following sources of variability were evaluated: (1) the interval to centrifugation of blood after collection, (2) the temperature and (3) safe time for storing the plasma after cold centrifugation, (4) the effect of fasting. Plasma ACE activity was 20.6 ± 7.7 U/mL, 20.9 ± 8 U/mL, and 20.5 ± 7.9 U/mL (n = 25) when samples were centrifuged immediately, after 1 hour of blood sampling, and after 3 hours of blood sampling, respectively (not significant). In plasma kept at −20°C, ACE activity was not different after 1 week (17.4 ± 4.3 U/mL) nor after 1 month (17.9 ± 4 U/mL), whereas baseline ACE was 16.7 ± 4.3 U/mL (n = 10). In plasma stored at −80°C, ACE activity was 15.5 ± 5.7 U/mL after 1 month (baseline 15 ± 5.3 U/mL; not significant; n = 12). No evidence for hydrolysis of the reaction product of ACE (hisleu dipeptide) was observed in plasma samples kept for 1 month at −20°C or at −80°C (by high-performance liquid chromatography analysis). In plasma obtained before breakfast, ACE activity was 12.8 ± 7.1 U/mL, and it was 12.3 ± 7.5 U/mL 2 hours afterwards (not significant; n = 12). Thus, to determine human plasma ACE activity by fluorimetry with reliability, with Z-phenylalanine-histidyl-leucine used as a substrate, there is a safe interval of at least 3 hours before blood centrifugation at −4°C. Plasma may be kept at −20°C or at −80°C for at least 4 weeks before final processing. Fasting does not influence its enzymatic activity.

Comparative effects of oxygen supplementation on theophylline and acetaminophen clearance in human cirrhosis

Background & Aims: Sinusoidal capillarization in cirrhosis may impair the transfer of oxygen into hepatocytes; this may contribute to impaired oxidative drug metabolism. The aim of this study was to test this hypothesis by comparing the effects of oxygen supplementation in cirrhotic patients on the clearance of theophylline, which is dependent on hepatic oxidative metabolism, with its effect on the clearance of acetaminophen, which is reliant on hepatic conjugation reactions. Methods: Ten cirrhotic patients awaiting liver transplant and 5 control subjects were studied. Oral acetaminophen (1000 mg) and intravenous theophylline (3 mg/kg) were administered simultaneously on two separate occasions, 7 days apart. Subjects were randomized to breathe either room air or oxygen via face mask at 12 L/min for 9 hours of blood sampling. Results: Theophylline and acetaminophen clearances were significantly reduced by a mean of 54% and 50%, respectively, in cirrhotic patients compared with controls. Oxygen supplementation improved plasma theophylline clearance in cirrhotic patients by a mean of 34% ( P = 0.001), whereas acetaminophen clearance remained unchanged. Conclusions: These findings indicate that, in cirrhosis, impaired hepatocyte oxygenation contributes to reduced oxidative drug metabolism and that oxidative drug metabolism can be improved by oxygen supplementation. GASTROENTEROLOGY 1999;116:915-920

Effect of corticotropin-releasing hormone antagonist on oestrogen-dependent glucoprivic suppression of luteinizing hormone secretion in female rats.

Pharmacological reduction of glucose availability with 2-deoxyglucose (2DG) suppresses pulsatile luteinizing hormone (LH) secretion in rats and growth-retarded lambs. Gonadal steroids enhance the glucoprivic suppression of LH secretion in rats. The present study determined if corticotropin-releasing hormone (CRH) plays a role in mediating oestrogen-dependent and -independent glucoprivic suppression of LH secretion. The study was conducted in ovariectomized (OVX) rats some of which received Silastic implants containing oestradiol-17beta (OE2) dissolved in peanut oil at 20 microg/ml to produce a physiological plasma level of OE2 (30 pg/ml). Seven days after ovariectomy, the rats were stereotaxically implanted with a guide cannula into the third cerebral ventricle. Seven days later, blood samples were collected through an indwelling atrial cannula every 6 min for 3 h for LH pulse determination. After the first hour of blood sampling, a CRH antagonist, [D-Phe12, Nle21,38]hCRF-(21-41), or vehicle was injected into the third cerebral ventricle through the implanted cannula before 2DG administration through the indwelling atrial cannula. Pulsatile LH secretion was suppressed by 2DG (200 mg/kg b.w.) in the vehicle-treated rats bearing OE2 implants. The CRH antagonist (5.65 nmol) blocked the suppressive effect of 2DG on pulsatile LH secretion in the OE2-treated OVX animals. On the other hand, in the absence of oestrogen, the effect of a twice greater dose of 2DG (400 mg/kg b.w.) was not blocked by five times greater amount of CRH antagonist (28.3 nmol). These results suggest the mechanisms mediating glucoprivic suppression of LH secretion involve two components: one is oestrogen-dependent and the other oestrogen-independent. CRH may be involved in the oestrogen-dependent component of glucoprivic suppression of LH secretion but not the oestrogen-independent one.

Suppression of luteinizing hormone pulses by restriction of glucose availability is mediated by sensors in the brain stem.

The availability of metabolic fuels such as glucose is known to influence reproductive function. Peripheral administration of 2-deoxyglucose (2DG), a competitive inhibitor of glycolysis, inhibits pulsatile LH secretion in the rat and growth-retarded lamb. We hypothesized that such glucoprivic suppression of LH secretion is mediated by the lower brain stem, because studies of both ingestive and reproductive behavior implicate lower brain stem structures, such as the area postrema, as a site that is sensitive to glucose availability. In the present study, the effect of a 2DG infusion, targeted to the fourth ventricle, on pulsatile LH secretion was examined in male rats. The males were castrated or castrated and immediately implanted with testosterone. Blood samples were collected through an indwelling atrial cannula every 6 min for 4 h for LH determination. After the first hour of blood sampling, 2DG (4 or 40 mg/kg) was infused into the fourth ventricle at a flow rate of 0.2 microliter/min through a cannula that had been stereotaxically implanted 1 week before sampling. The high dose of 2DG (40 mg/kg), but not the low dose (4 mg/kg), suppressed pulsatile LH secretion and increased food intake in both castrated and testosterone-treated castrated rats. LH secretion and food intake were not affected by the infusion of xylose (40 mg/kg) as an isoosmotic control. The site specificity of the 2DG treatment was confirmed by histological examination after an isovolumetric infusion of dye (0.2 microliter/min). These results suggest that glucose availability could influence LH secretion as well as feeding through a central sensor in the lower brain stem and are consistent with the idea that the area postrema might be an important glucosensor involved in the modulation of LH secretion.

Delivery of dehydroepiandrosterone to premenopausal women: Effects of micronization and nonoral administration

OBJECTIVES: This single-dose study compares three dehydroepiandrosterone delivery methods (oral crystalline steroid, micronized steroid, and vaginal administration) to ascertain whether physiologic levels of circulating dehydroepiandrosterone and dehydroepiandrosterone sulfate can be obtained while increases in testosterone are minimized. STUDY DESIGN: Two randomized, double-blind, placebo-controlled single-dose comparisons were made. For oral micronized versus crystalline dehydroepiandrosterone 300 mg doses of micronized or crystalline dehydroepiandrosterone were administered, followed by 6 hours of blood sampling ( n = 7). Serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone levels were measured; areas under the curve and mean peak values were analyzed by Student - Newman-Keuls tests. For oral versus vaginal micronized dehydroepiandrosterone 150 mg oral or vaginal doses of micronized dehydroepiandrosterone were administered, followed by blood sampling over 12 hours ( n = 5). Data analysis was as described. RESULTS: Oral micronized and unmicronized dehydroepiandrosterone resulted in increases in serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone. Micronization increased the area-under-the-curve ratios for dehydroepiandrosterone sulfate/dehydroepiandrosterone and dehydroepiandrosterone sulfate/testosterone. Vaginal administration provided equivalent serum dehydroepiandrosterone; however, it failed to increase dehydroepiandrosterone sulfate or testosterone over placebo. CONCLUSION: Micronization of oral dehydroepiandrosterone diminishes bioconversion to testosterone. Vaginal dehydroepiandrosterone delivers equivalent dehydroepiandrosterone but substantially diminishes dehydroepiandrosterone bioconversion. (A M J O BSTET G YNECOL 1996;174:649-53.)

Involvement of the catecholaminergic input to the paraventricular nucleus and of corticotropin-releasing hormone in the fasting-induced suppression of luteinizing hormone release in female rats.

The roles of the adrenergic projection to the paraventricular nucleus (PVN) and of central CRH in the suppression of pulsatile LH secretion during 48-h fasting were examined in ovariectomized estradiol (E2)-treated rats. The animals were ovariectomized and immediately implanted with Silastic tubing containing E2. One week after ovariectomy and E2 implantation, the animals were implanted stereotaxically with a guide cannula for microinjection into the PVN or intracerebroventricular (icv) injection. One week later, some of the animals were deprived of food for 48 h. The unfasted controls were provided with food ad libitum. At this point, blood samples were collected every 6 min for 3 h. Animals received an injection of 50 micrograms alpha-methyl-p-tyrosine (AMPT), a catecholamine synthesis inhibitor, into the PVN 3 h before the sampling started or an icv injection of 26 nmol alpha-helical CRF-(9-41), a CRH antagonist, after the first hour of blood sampling; control animals were given the vehicle at the equivalent time. The fasted animals injected with AMPT showed a significantly higher mean LH concentration and LH pulse frequency over the 3-h sampling period compared with the vehicle-injected controls. Treatment with AMPT had no significant effect on LH secretion in unfasted animals. The icv injection of alpha-helical CRF-(9-41) reinstated the suppressed LH release in fasted rats, but had no significant effect in unfasted animals. These results suggest that the adrenergic projection to the PVN and central CRH are involved in the suppression of pulsatile LH release during food deprivation. The possibility that fasting activates an ascending adrenergic projection that stimulates CRH release and thus suppresses pulsatile LH secretion is discussed.