A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women

OBJECTIVE: To evaluate the ovarian follicular dynamics of cycle modification with the aromatase inhibitor letrozole compared with clomiphene citrate in normal ovulatory women. DESIGN: Randomized double-blind controlled trial. SETTING: Tertiary care hospital. PATIENT(S): Nineteen ovulatory female volunteers, ages 18-35 years. INTERVENTION(S): Subjects were monitored in one control cycle. Subjects then received either letrozole 2.5 mg daily or clomiphene citrate 50 mg daily on days 5-9 after menses. MAIN OUTCOME MEASURE(S): Number of mature follicles, endometrial thickness and endometrial pattern at ovulation, and follicular profiles of LH, FSH, and E(2). RESULT(S): The number of mature follicles at the LH surge in natural cycles was 1.0 with an exaggerated response seen for treatment both with clomiphene and letrozole. There was no difference in the endometrial thickness at midcycle during either the natural cycles or the medicated cycles. LH surges and spontaneous ovulation were documented in all natural and medicated cycles. When measured daily, follicular profiles of LH and FSH are similar between the groups in both the natural and medicated cycles. In the medicated cycles, clomiphene results in a significant increase in E(2) levels, while E(2) levels in letrozole-stimulated cycles appeared lower than in natural cycles. CONCLUSION(S): Transient inhibition of aromatase activity in the early follicular phase with the aromatase inhibitor letrozole results in stimulation of ovarian folliculogenesis similar to that seen with clomiphene citrate with no apparent adverse effect on endometrial thickness or pattern at midcycle.     

Cutaneous reactions to aspirin and nonsteroidal antiinflammatory drugs

Soon after the introduction of aspirin for the treatment of pain, fever, and inflammation more than a century ago, clinicians were challenged by the frequent observation of ASA-triggered allergic and pseudoallergic reactions occurring in the skin. This problem was further enhanced by the development of a number of other analgesic and antiinflammatory drugs that, having different chemical structures, cross-reacted with acetilsalycilic acid in many patients. This paper reviews the information presently available for the management of individuals who develop urticaria and angioedema when exposed to drugs that inhibit cyclooxygenase isoenzymes. The immune and nonimmunologic mechanisms leading to the pathogenesis of such reactions, their prevalence in selected groups of the population, clinical picture, and useful diagnostic approaches are described, and current guidelines used in our institutions for the clinical orientation of the patients, taking advantage of the recent introduction of various new and more selective NSAIDS that inhibit preferentially the COX-2 enzyme, are proposed.     

Dopaminergic Transmission in the Rat Striatum in Vivo in Conditions of Pharmacological Modulation

The effects of pharmacological modulation of striatal dopaminergic neurotransmission were studied in freely mobile rats by intracerebral microdialysis and HPLC to assay dopamine and dopamine metabolite levels and the rate of dopamine synthesis, in combination with observations of stereotypical behavior. Inhibition of catechol O-methyltransferase (COMT) with tolcapone led to increases in extracellular dopamine levels only when the baseline dopamine level was elevated by administration of L-3,4-dihydroxyphenylalanine in combination with the decarboxylation inhibitor carbidopa. Increases in dopamine levels in striatal dialysates by blockade of reuptake were enhanced by inhibition of metabolic degradation of dopamine by tolcapone, a selective catechol O-methyltransferase inhibitor. GBR-12909, a blocker of the dopamine transporter, increased extracellular dopamine and induced motor stereotypy. Both of these effects were potentiated by tolcapone. The rate of dopamine biosynthesis decreased when reuptake was inhibited. These data provide evidence for the key role of the dopamine transporter in maintaining neurochemical homeostasis at the synaptic level.     

Robotic inhibition assay for determination of HMG-CoA reductase inhibitors in human plasma

The cholesterol-lowering drug simvastatin (SIMV, Zocor reduced heart attacks by 42% in patients who had high cholesterol levels and suffered from heart disease. Upon oral administration, SIMV is quickly hydrolyzed to its beta-hydroxyacid and other acid metabolites, which are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase. A Tecan-based enzyme inhibition assay has been developed to improve the existing Zymark-based assay for the determination of both active and total concentrations of HMG-CoA reductase inhibitors in human plasma. A Tecan Genesis 200 robotic workstation equipped with eight probes and customized hardware was utilized to achieve higher sample throughput and improve assay reproducibility and mechanical stability. The developed enzyme inhibition assay was validated over two concentration ranges of 0.4-20 ng equivalent/mL, and 2-50 ng equivalent/mL. Intra- and interday precision data (coefficient of variation (CV)) for both concentration ranges were less than 9%, with an accuracy of 93-107%. The interday precision for the determination of quality control (QC) samples was less than 2% and 8%, respectively. The respective interday QC accuracy values were 93-103% and 97-104%. Good linearity across the two concentration ranges was observed, with acceptable reproducibility. This improved enzyme inhibition assay has been utilized to analyze human plasma samples from several clinical studies.     

Antibodies to factor VIIa in patients with haemophilia and high-responding inhibitors

The haemostatic effect of by-passing agents such as activated prothrombin complex concentrates (aPCC) and recombinant factor VIIa is inadequate in some patients with severe haemophilia and high-responding inhibitors. Theoretically, this could be due to antibody reactivity to procoagulant proteins other than the deficient factor. To evaluate this hypothesis, immunoglobulin (Ig) fractions from six multi-transfused patients (three haemophilia A and three haemophilia B) were purified on protein A sepharose and then subjected to immunoaffinity chromatography on factor IX sepharose and factor VIIa sepharose. All three Ig fractions from the haemophilia B patients, but not commercially available Ig, contained antibodies that bound to both gels. None of the haemophilia A patients had antibodies to factor IX but all three had antibodies towards factor VIIa. The immunoaffinity purified antifactor IX and VIIa antibodies from the haemophilia B patients inhibited thrombin formation in vitro using Feiba as active enzyme, but had no significant effect in the presence of NovoSeven. In contrast, no inhibitory effect was observed with the antifactor VIIa antibodies from the haemophilia A patients. Cross-reactivity to factor IX was seen for the antifactor VIIa antibodies from the patients with haemophilia B. Our findings show that antibody reactivity to other procoagulant factors such as factor VIIa exists in patients with high-responding inhibitors and that these antibodies may have an inhibitory potential that correlates to the amount of active enzyme present. The characterization of the antibody profile may facilitate an optimal treatment with by-passing agents in severe bleeding events.     

Localization and measurement of extracellular plant galactosidases

A simple, rapid and sensitive procedure for the identification and determination of plant extracellular alpha-galactosidase and beta-galactosidase is described using callus cultures and seedlings from tomato. Synthetic substrates (1-naphthyl- and p-nitrophenyl-alpha-D- and beta-D-galactopyranosides) were used for the identification and determination of intracellular and extracellular activity of alpha-galactosidase and beta-galactosidase, respectively. Many iminosugars or azasugars are strong glycosidase inhibitors and some of them show promising chemotherapeutic effects against viral diseases, and are potentially antidiabetic agents, as well as antitumor agents. These facts initiated our interest in a rapid and sensitive assay to determine activity of alpha-galactosidase and beta-galactosidase in plant tissues. The results presented here show the potential of the assay of the activity of intracellular and extracellular galactosidases of plant origin in inhibitory and/or biotechnological studies.     

Effects of Ca-ATPase inhibitors on the intracellular calcium activity and motility of human spermatozoa

Although evidence suggests that high intracellular calcium activity ([Ca2+]i) inhibits sperm motility, data concerning [Ca2+]i within, or slightly above, the physiological range are sparse, particularly in mammalian sperm. We investigated inhibitors of the sarcoplasmic/endoplasmic reticulum Ca-ATPase (SERCA) and the plasma membrane Ca-ATPase with the objective of increasing the intracellular calcium ion activity in human spermatozoa to study its effect on motility and other functions. Thapsigargin (20 micromol/L) increased [Ca2+]i from 140 +/- 7 nmol/L over an approximately 2-min period to reach a plateau of 530 +/- 84 nmol/L (mean +/- SEM, n = 3, p < 0.05). In sperm suspended in calcium-free medium thapsigargin increased [Ca2+]i from 13 +/- 3.3 to 35 +/- 7.5 nmol/L (p < 0.01), consistent with the release of calcium from intracellular stores. Cyclopiazonic acid (60 micromol/L) caused a transient decrease in [Ca2+]i. Quercetin, (200 micromol/L) caused a rapid increase in [Ca2+]i to 1280 +/- 90 nmol/L, after which [Ca2+]i fell quickly at first but then more slowly. Thapsigargin (20 micromol/L) caused approximately 70% of sperm to acrosome react in < or = 5 min, but once acrosome reacted, many sperm died over the next 30 min. Lower concentrations of thapsigargin caused fewer acrosome reactions but were less toxic. Both thapsigargin and quercetin caused rapid dose-dependent decreases in sperm motility. The results are consistent with high [Ca2+]i in the range observed in caput epididymal or cryopreserved spermatozoa inhibiting motility, but might be confounded by other events following the acrosome reaction.     

Development of silicone rubber hollow fiber membrane oxygenator for ECMO

Silicone rubber hollow fiber membrane produces an ideal gas exchange for long-term ECMO due to nonporous characteristics. The extracapillary type silicone rubber ECMO oxygenator having an ultrathin hollow fiber membrane was developed for pediatric application. The test modules were compared to conventional silicone coil-type ECMO modules. In vitro experiments demonstrated a higher O2 and CO2 transfer rate, lower blood flow resistance, and less hemolysis than the conventional silicone coil-type modules. This oxygenator was combined with the Gyro C1E3 centrifugal pump, and three ex vivo experiments were conducted to simulate pediatric V-A ECMO condition. Four day and 6 day experiments were conducted in cases 1 and 2, respectively. Case 3 was a long-term experiment up to 2 weeks. No plasma leakage and stable gas performances were achieved. The plasma free hemoglobin was maintained within a normal range. This compact pump-oxygenator system in conjunction with the Gyro C1E3 centrifugal pump has potential for a hybrid total ECMO system.     

In vivo test of pressure head and flow rate estimation in a continuous-flow artificial heart

To avoid using sensors with low biocompatibility and low durability in implantable total artificial heart (TAH) systems, the authors previously proposed a new method for estimating instantaneous values of flow rate and pressure head on the basis of voltage, current, and rotational speed in a motor driven centrifugal pump. The previous in vitro experiments showed that the proposed estimator could automatically compensate for the effect of the change in blood viscosity on the estimation accuracy by employing two kinds of autoregressive exogenous models. In this study, validity and reliability of this estimation method were ascertained in an acute animal experiment. In the experiment, two centrifugal blood pumps were implanted into an adult goat as a total artificial heart. Results of estimation were compared with true values when blood viscosity was changed by injecting physiological saline. The results indicated that the system could successfully estimate pressure head by compensating the change of viscosity, although the estimation accuracy of the in vivo estimation was not so high as that of the previous in vitro tests.     

Impairment of the blood-brain barrier can result in tacrolimus-induced reversible leucoencephalopathy following heart transplantation

Fatal leucoencephalopathy is a rare calcineurin inhibitor-related complication, especially in kidney and liver transplant recipients. The only means of clinical management reported so far is the discontinuation or reduction in the calcineurin inhibitor. We herein report a case of a 37-yr-old male who developed leucoencephalopathy 12 wk after heart transplantation and recovered after stabilization of metabolism and arterial blood pressure. The findings in this case support the hypothesis that tacrolimus-associated neurotoxicity is severely increased by an impairment of the blood-brain barrier. Withdrawal of tacrolimus was not necessary while other causes of endothelial injury were treated successfully.