Association between Weight-Adjusted Waist Index and depressive symptoms: A nationally representative cross-sectional study from NHANES 2005 to 2018

BACKGROUND

Depressive symptoms are strongly associated with the development of various diseases and are one of the leading causes of disability in the world. However, the relationship between weight-adjusted waist index (WWI) and depressive symptoms has not been studied. This study aimed to assess the relationship between depressive symptoms and WWI.

METHODS

This study took NHANES data from 2005 to 2018 with 32,374 participants. Depressive symptoms were measured by a questionnaire (PHQ-9).WWI was determined by dividing the square root of waist circumference (cm) by weight (kg). Multivariate logistic regression models, smoothed curve fitting, and weighted generalized additive model (GAM) regression were used to examine the relationship between depressive symptoms and WWI, BMI, and waist circumference. Subgroup analyses and interaction tests were also performed.

RESULTS

In fully adjusted models, the OR (95 % CI) for WWI and depressive symptoms with WWI, BMI, and waist circumference were 1.18 (1.05, 1.34), BMI 1.01 (1.00, 1.02, 1.01 (1.00, 1.01), respectively. Participants in the highest quartile (Q4) had a 49 % higher depressive symptoms compared to those in the lowest quartile (Q1) (OR = 1.49, 95 % CI:1.14-1.96). Subgroup analyses and interaction tests showed a stable relationship between depressive symptoms and WWI.

LIMITATIONS

It is difficult to determine a causal relationship between the two; questionnaire collection may be somewhat biased; CONCLUSIONS: WWI was positively associated with depressive symptoms. This association was stronger than BMI and waist circumference. However, this relationship was stable. This study emphasizes the potential utility of WWI in preventing depressive symptoms and improving prognosis in the population.

TransRNAm: Identifying Twelve Types of RNA Modifications by an Interpretable Multi-Label Deep Learning Model Based on Transformer

Accurate identification of RNA modification sites is of great significance in understanding the functions and regulatory mechanisms of RNAs. Recent advances have shown great promise in applying computational methods based on deep learning for accurate prediction of RNA modifications. However, those methods generally predicted only a single type of RNA modification. In addition, such methods suffered from the scarcity of the interpretability for their predicted results. In this work, a new Transformer-based deep learning method was proposed to predict multiple RNA modifications simultaneously, referred to as TransRNAm. More specifically, TransRNAm employs Transformer to extract contextual feature and convolutional neural networks to further learn high-latent feature representations of RNA sequences relevant for RNA modifications. Importantly, by integrating the self-attention mechanism in Transformer with convolutional neural network, TransRNAm is capable of not only capturing the critical nucleotide sites that contribute significantly to RNA modification prediction, but also revealing the underlying association among different types of RNA modifications. Consequently, this work provided an accurate and interpretable predictor for multiple RNA modification prediction, which may contribute to uncovering the sequence-based forming mechanism of RNA modification sites.

Effect of PITX2 genetic variants on the susceptibility to stroke in the Chinese Han population

PURPOSE

Stroke is a multifactorial and complex disease caused by the obstruction or rupture of cerebrovascular. To explore the influence of genetic factors on stroke susceptibility, we investigated the association between four single nucleotide polymorphisms (SNPs) in the paired-like homeodomain transcription factor 2 (PITX2) gene and stroke risk.

METHODS

A total of 977 volunteers including 476 stroke patients and 501 control individuals were recruited. The association between PITX2 polymorphisms and stroke risk was evaluated using genetic models and haplotype analyses. The strength of the association between each studied polymorphisms and stroke risk was evaluated by calculating odds ratios (ORs) and 95% confidence intervals (CIs). What's more, multifactor dimensionality reduction (MDR) was used to predict the interaction between SNPs.

RESULTS

Our study showed that rs6817105 in PITX2 was related to a significant increase in stroke susceptibility (OR = 1.42, 95% CI = 1.04-1.94, p = 0.028). Stratified analyses based on gender indicated that rs6817105, rs13143308, and rs6843082 polymorphisms were significantly associated with an increased risk of stroke in male (OR = 0.68, 95% CI = 0.47-0.99, p = 0.042; OR = 0.53, 95% CI = 0.30-0.96, p = 0.035; and OR = 0.55, 95% CI = 0.30-0.99, p = 0.047). Besides, SNP rs6817105 was significantly increased the risk of stroke in people at age over 65 years (OR = 1.87, 95% CI =1.12-3.11, p = 0.016). MDR showed that the interaction model of rs6817105 and rs3853445 emerged as the best predictor between the PITX2 gene and stroke susceptibility.

CONCLUSIONS

This study indicated that there was a significant association between the PITX2 gene and stroke risk, and provided some data as far as possible to support the prevention of stroke.

Improved Characterization and Accurate Modelling of Drain Current Derivatives of InP Based High Electron Mobility Transistors Devices

InP based HEMTs are of great importance, due to their enormous potential in a high-speed modern microwave circuit, power amplifier, and low noise amplifier applications. Therefore, an accurate non-linear equivalent circuit model of HEMTs is very important for an accurate circuit design. This paper presents improved characterization and accurate modelling of drain current derivatives of InP based HEMTs devices. The proposed model is simple, easy to extract, and suitable for implementation in simulation tools. The Ψ function is extended to increase the flexibility of the proposed model. A gate-drain dependent current source is added to increase the S-parameter fitting. A one-dimensional intrinsic multi-bias capacitances model is introduced to avoid convergence failure. The fitting results of the I-V characteristics and its high order derivatives show high accuracy. In addition, S-parameters and P_out for the proposed model are compared with the original Angelov model. The proposed model shows better accuracy.

Analysis of Passivation Techniques in InP HEMTs and Implementation of an Analytical Model of fT Based on the Small Signal Equivalent Circuit

This paper analyses, the influence of Si₃N₄-PECVD and Al₂O₃-ALD surface passivation on the DC and RF characteristics of InP HEMTs with different gate lengths 0.08 μm, 0.1 μm, 0.12 μm, and 0.15 μm. A significant improvement in maximum drain current I_{DS, MAX}, transconductance g_{m, MAX} and oscillation frequency f_{max, MAX} is obtained by scaling the thickness of the passivation layers An increase in g_{m, MAX} and f_{max, MAX}, f_{T, MAX} is observed by reducing parasitic capacitance w.r.t. the decrease in gate length. In addition, an analytical model of f_T based on a small-signal equivalent circuit is developed, which consist of extrinsic parameters R_s, R_d, C_{gs_ext} and C_{gd_ext} and intrinsic parameters C_gsi, C_gdi, g_mi and g_oi. The carrier transport is improved by increasing g_mi, thus the transit time τ_t , the parasitic charging delay τ_ext and the τ_par are reduced by lowering the extrinsic capacitances. An excellent fitting between measured and simulated f_T is achieved, which inturn leads a realistic way for further improvement in f_T.

Daphnetin protects hippocampal neurons from oxygen-glucose deprivation-induced injury

Daphnetin, a coumarin derivative extracted from Daphne odora var., was reported to possess a neuroprotective effect. Recently, it has been demonstrated that daphnetin attenuates ischemia/reperfusion (I/R) injury. However, the role of daphnetin in cerebral I/R injury and the potential mechanism have not been fully understood. The present study aimed to explore the regulatory roles of daphnetin on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cell injury in a model of hippocampal neurons. Our results demonstrated that daphnetin improved cell viability and reduced the lactate dehydrogenase leakage in OGD/R-stimulated hippocampal neurons. In addition, daphnetin inhibited oxidative stress and cell apoptosis in hippocampal neurons after OGD/R stimulation. Furthermore, daphnetin significantly enhanced the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression in hippocampal neurons exposed to OGD/R. Knockdown of Nrf2 blocked the protective effect of daphnetin on OGD/R-induced hippocampal neurons. In conclusion, these findings demonstrated that daphnetin attenuated oxidative stress and neuronal apoptosis after OGD/R injury through the activation of the Nrf2/HO-1 signaling pathway in hippocampal neurons. Thus, daphnetin may be a novel therapeutic agent for cerebral I/R injury.

Pharmacokinetic and Pharmacodynamic Drug Interaction Study of Piragliatin, a Glucokinase Activator, and Glyburide, a Sulfonylurea, in Type 2 Diabetic Patients

A glucokinase activator and a sulfonylurea might be coprescribed to synergize treatment success for type 2 diabetes (T2D). This clinical pharmacology study was designed to investigate the potential glucose-lowering effect or pharmacodynamic (PD), pharmacokinetic (PK), and safety/tolerability interactions between piragliatin and glyburide in T2D patients already taking glyburide but not adequately controlled. This was an open-label, multiple-dose, 3-period, single-sequence crossover design: on days -1, 6, and 12, PD and PK samples were drawn with glyburide alone (period 0), piragliatin + glyburide (period 1), and piragliatin alone (period 2) treatments. The glucose-lowering effect, including fasting plasma glucose (FPG), of piragliatin was more pronounced when it was administered concomitantly with glyburide as compared to piragliatin or glyburide administered alone. However, this enhancement cannot be explained by a potential PK interaction between piragliatin and glyburide. Other than hypoglycemia, there were no clinically relevant safety findings. Thus, the enhanced PD effect warrants further investigation to define the optimal dose combination between glucokinase activators and sulfonylureas with regard to efficacy, safety, and tolerability.

Intravenous thrombolysis guided by a telemedicine consultation system for acute ischaemic stroke patients in China: the protocol of a multicentre historically controlled study

INTRODUCTION

The rate of intravenous thrombolysis with tissue-type plasminogen activator or urokinase for stroke patients is extremely low in China. It has been demonstrated that a telestroke service may help to increase the rate of intravenous thrombolysis and improve stroke care quality in local hospitals. The aim of this study, also called the Acute Stroke Advancing Program, is to evaluate the effectiveness and safety of decision-making concerning intravenous thrombolysis via a telemedicine consultation system for acute ischaemic stroke patients in China.

METHODS AND ANALYSIS

This is a multicentre historically controlled study with a planned enrolment of 300 participants in each of two groups. The telestroke network consists of one hub hospital and 14 spoke hospitals in underserved regions of China. The usual stroke care quality in the spoke hospitals without guidance from the hub hospital will be used as the historical control. The telemedicine consultation system is an interactive, two-way, wireless, audiovisual system accessed on portable devices. The primary outcome is the percentage of patients treated with intravenous thrombolysis within 4.5 h of stroke onset.

ETHICS AND DISSEMINATION

The project has been approved by the Institutional Review Board of Xijing Hospital. The results will be published in scientific journals and presented to local government and relevant institutes.

TRIAL REGISTRATION NUMBER

NCT02088346 (12 March 2014).

Comparative analysis of the role of JNK signaling pathway in regulating cell proliferation and apoptosis of rat liver regeneration and rat acute hepatic failure

To compare the role of JNK signaling pathway in rat liver regeneration (LR) and in rat acute hepatic failure (AHF) occurrence at the gene transcription level, Rat Genome 230 2.0 array was used to detect the gene expression profiles of the two processes, and bioinformatics and systems biology methods were applied to analyze the physiological activities uncovered by their gene expression profiles in this study. The results showed that 240 genes were included in the array above, though there were 302 genes related to forty two paths of JNK signaling pathway. Array detection results demonstrated that 52 genes were significantly expressed during LR, 20 genes in AHF occurrence, and 15 genes in both of above two processes. Synergy values of these genes were calculated using a mathematical model established by our lab, which revealed the following. The cell proliferation-promoting effects of paths 1, 16 and paths 1-17 of JNK signaling pathway were stronger than the control at 6-12 h and 72 h of LR, respectively, while the cell proliferation-promoting effects of paths 1-17 and the cell proliferation-inhibiting effects of path 34-35 were weaker at 6h of AHF occurrence. The cell apoptosis-promoting effects of paths 22-23 were much stronger at 6, 12 and 72 h of LR and at 12, 24 h of AHF occurrence. In conclusion, thirty eight paths of JNK signaling pathway regulate cell proliferation and apoptosis in both LR and AHF occurrence.

A phase Ib study of pertuzumab, a recombinant humanised antibody to HER2, and docetaxel in patients with advanced solid tumours

Pertuzumab represents the first in a new class of targeted therapeutics known as HER dimerisation inhibitors. We conducted a phase Ib study to determine the maximum-tolerated dose, the dose limiting toxicities (DLT), and pharmacokinetic (PK) interaction of docetaxel when administered in combination with pertuzumab. Initially, two dose levels of docetaxel (60 and 75 mg m⁻²) were explored in combination with a fixed dose of 1050 mg of pertuzumab; then two dose levels of docetaxel (75 and 100 mg m⁻²) were explored in combination following a fixed dose of 420 mg of pertuzumab with a loading dose of 840 mg. Both drugs were administered intravenously every 3 weeks. The latter dose of pertuzumab was allowed after an amendment to the original protocol when phase II data suggesting no difference in toxicity or activity between the 2 doses became available. Two patients out of two treated at docetaxel 75 mg m⁻² in combination with pertuzumab 1050 mg suffered DLT (grade 3 diarrhoea and grade 4 febrile neutropaenia). Two out of five patients treated at docetaxel 100 mg m⁻² in combination with pertuzumab 420 mg with a loading dose of 840 mg suffered DLT (grade 3 fatigue and grade 4 febrile neutropaenia). Stable disease was observed at four cycles in more than half of the patients treated and a confirmed radiological partial response with a >50% decline in PSA in a patient with hormone refractory prostate cancer were observed. There were no pharmacokinetic drug–drug interactions. The recommended phase II dose of this combination was docetaxel 75 mg m⁻² and 420 mg pertuzumab following a loading dose of 840 mg.

Pheochromocytomas in Nf1 knockout mice express a neural progenitor gene expression profile

Pheochromocytomas are adrenal medullary tumors that typically occur in adult patients, with increased frequency in multiple endocrine neoplasia type 2, von Hippel-Lindau disease, familial paraganglioma syndromes and neurofibromatosis type 1 (NF1). Pheochromocytomas arise in adult mice with a heterozygous knockout mutation of exon 31 of the murine Nf1 gene, providing a mouse model for pheochromocytoma development in NF1. We performed a microarray-based gene expression profiling study comparing mouse pheochromocytoma tissue to normal adult mouse adrenal medulla to develop a basis for studying the pathobiology of these tumors. The findings demonstrate that pheochromocytomas from adult neurofibromatosis knockout mice express multiple developmentally regulated genes involved in early development of both the CNS and peripheral nervous system. One of the most highly overexpressed genes is receptor tyrosine kinase Ret, which is known to be transiently expressed in the developing adrenal gland, down-regulated in adult adrenals and often overexpressed in human pheochromocytomas. Real-time polymerase chain reaction validated the microarray results and immunoblots confirmed the overexpression of Ret protein. Other highly expressed validated genes include Sox9, which is a neural crest determinant, and Hey 1, which helps to maintain the progenitor status of neural precursors. The findings are consistent with the recently proposed concept that persistent neural progenitors might give rise to pheochromocytomas in adult mouse adrenals and suggest that events predisposing to tumor development might occur before formation of the adrenal medulla or migration of cells from the neural crest. However, the competing possibility that developmentally regulated neural genes arise secondarily to neoplastic transformation cannot be ruled out. In either case, the unique profile of gene expression opens the mouse pheochromocytoma model to new applications pertinent to neural stem cells and suggests potential new targets for treatment of pheochromocytomas or eradication of their precursors.

Differential expression of neuroleukin in osseous tissues and its involvement in mineralization during osteoblast differentiation

Osteoblast differentiation is a multistep process that involves critical spatial and temporal regulation of cellular processes marked by the presence of a large number of differentially expressed molecules. To identify key functional molecules, we used differential messenger RNA (mRNA) display and compared RNA populations isolated from the defined transition phases (proliferation, matrix formation, and mineralization) of the MC3T3-E1 osteoblast-like cell line. Using this approach, a complementary DNA (cDNA) fragment was isolated and identified as neuroleukin (NLK), a multifunctional cytokine also known as autocrine motility factor (AMF), phosphoglucose isomerase (PGI; phosphohexose isomerase [PHI]), and maturation factor (MF). Northern analysis showed NLK temporal expression during MC3T3-E1 cell differentiation with a 3.5-fold increase during matrix formation and mineralization. Immunocytochemical studies revealed the presence of NLK in MC3T3-E1 cells as well as in the surrounding matrix, consistent with a secreted molecule. In contrast, the NLK receptor protein was detected primarily on the cell membrane. In subsequent studies, a high level of NLK expression was identified in osteoblasts and superficial articular chondrocytes in bone of 1-, 4-, and 8-month-old normal mice, as well as in fibroblasts, proliferating chondrocytes, and osteoblasts within a fracture callus. However, NLK was not evident in hypertrophic chondrocytes or osteocytes. In addition, treatment of MC3T3 cells with 6-phosphogluconic acid (6PGA; a NLK inhibitor) resulted in diminishing alkaline phosphatase (ALP) activity and mineralization in MC3T3-E1 cells, especially during the matrix formation stage of differentiating cells. Taken together, these data show specific expression of NLK in discrete populations of bone and cartilage cells and suggest a possible role for this secreted protein in bone development and regeneration.

Orlistat maintains biliary lipid composition and hepatobiliary function in obese subjects undergoing moderate weight loss

OBJECTIVES

Orlistat, an intestinal lipase inhibitor, has recently been approved by the US Food and Drug Administration for treatment of obesity. The effects of orlistat on hepatobiliary function have not been previously defined. A 4 wk study was performed involving modest weight loss in obese subjects to observe any short-term hepatobiliary responses that occur after initiating treatment with orlistat and a hypocaloric diet.

METHODS

A total of 23 obese (BMI 30-41 kg/m2) subjects were randomized to a double blind t.i.d. treatment with 120 mg of orlistat or a placebo in conjunction with a hypocaloric diet (1200-1500 kcal/day). The study was designed to achieve similar modest weight loss in both groups in order to be able to directly assess the effects of orlistat. Cholesterol saturation, bile composition, and gallbladder motility were measured.

RESULTS

At the end of the treatment period, mean weight loss of 3.8 kg was achieved in the orlistat group (vs 2.3 kg with placebo, p = NS). Total bile acid concentration decreased significantly with placebo (-18.57 +/- 6.99 mmol/L; 95% CI = -32.26 to -4.87), but not with orlistat. Biliary phospholipid concentration decreased significantly with placebo (-4.38 +/- 1.91 mmol/L; 95% CI = -8.13 to -0.64) but not with orlistat. Mean changes from the baseline in cholesterol saturation index and gallbladder motility were similar in both groups. Microscopy of bile failed to reveal cholesterol microcrystals before or after treatment in either group.

CONCLUSIONS

Our findings indicate a primary initial effect of weight loss is a reduction in biliary bile acids and phospholipids. Orlistat blocks these adverse changes in biliary lipid composition and maintains hepatobiliary function. We speculate that the risk of formation of gallstones during weight loss may actually be lowered with orlistat.

Orlistat fails to alter postprandial plasma lipid excursions or plasma lipases in normal-weight male volunteers

OBJECTIVES

After 10 d of orlistat administration (120 mg three times/day), the primary objective was to determine the drug's effect on postprandial plasma lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) activities on day 10 after an oral fat-load. The secondary objectives were to determine the effects of orlistat on 12 h postprandial measures of: (1) preheparin HTGL and LPL; and (2) serum triglycerides, very-low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and free fatty acids.

METHODS

Twenty-four normal-weight, healthy male volunteers were randomized to either 120 mg orlistat (n=12) or placebo (n=12) three times a day with meals for 10 d. Preheparin LPL and HTGL activities and LPL specific activity were measured in the fasted state on days 1, 5, and 10. On days 5 and 10 the study medication (orlistat or placebo) was taken at the beginning of a fat-rich breakfast and serum lipid and lipoprotein levels monitored for 12 h postprandially. On day 10, 15 min postheparin HTGL activity was measured 8 h after the fat-rich breakfast.

RESULTS

No differences were found between groups in fasting levels of preheparin LPL or HTGL activity or in LPL-specific activity on days 1, 5 and 10. No difference was found between the two treatment groups in postheparin HTGL activity 8 h after the fat-rich breakfast. Also, no differences were found between the two groups in plasma triglycerides or lipoproteins.

CONCLUSION

The results indicate that the oral administration of orlistat (120 mg t. i.d.) does not significantly alter plasma triglycerides or lipoproteins, and that the inhibitory effect of orlistat on lipases is limited to the gastrointestinal tract and is not manifested systemically.

Lrp binds to two regions in the dadAX promoter region of Escherichia coli to repress and activate transcription directly

The dadAX operon is expressed by multiple promoters that are repressed by leucine-responsive regulatory protein (Lrp) and activated by cyclic AMP-CRP. In previous work, we found that alanine or leucine acted as inducers to antagonize Lrp repression of the three major promoters directly. Here, we identify 11 Lrp binding sites located within 350 bp of dad DNA. A mutational analysis, coupled with in vivo and in vitro transcription experiments, indicated that Lrp sites that overlap the dad promoters were involved in repression. In contrast, sites upstream of the promoters did not appear to be necessary for repression, but were required for activation by Lrp plus alanine or leucine of one of the major dad promoters, P2. This activation by alanine or leucine was not simply relief of repression, as P2 transcription from a constitutive template was increased fivefold compared with the basal level of transcription found in the absence of Lrp and the co-activator cyclic AMP-CRP. Alanine or leucine decreased the affinity of Lrp to repressor sites, while having little or no effect on the binding of Lrp to activator sites. This differential effect of alanine and leucine on Lrp binding helps to explain how these modifiers influence both repression and activation of the dad operon.

Long-term systemic exposure of orlistat, a lipase inhibitor, and its metabolites in obese patients

Orlistat, a lipase inhibitor, acts locally in the gastrointestinal tract; its systemic exposure is not required for its efficacy. However, knowledge of the extent of its systemic exposure is important for its safe use in obese patients, the intended target population. Pharmacokinetic screening in obese patients was carried out by monitoring plasma concentrations of unchanged orlistat and its metabolites in five key double-blind, placebo-controlled phase II/III studies. Results of these studies involving the monitoring of plasma samples indicate that detection of intact orlistat in plasma was sporadic, and measurable concentrations were low (< 10 ng/mL or 0.02 microM) without evidence of accumulation, which is consistent with minimal absorption. It is concluded that systemic exposure of orlistat is negligible; at a clinically efficacious dose level, orlistat is unlikely to produce systemic lipase inhibition.

The interaction of the lipase inhibitor orlistat with ethanol in healthy volunteers

OBJECTIVES

The primary objective was to investigate the possible interference of ethanol on the orlistat effect on inhibition of dietary fat absorption and the possible interference of orlistat on the pharmacokinetics of ethanol. Secondary objectives were to assess the tolerability during concomitant dosing of orlistat and ethanol and to determine the ethanol effect on plasma levels of orlistat.

METHODS

This was a double-blind, placebo-controlled, parallel, randomized study performed in 30 (three parallel groups of ten subjects each) healthy normal weight male subjects between the ages of 20 and 30 years. A 5-day run-in period to accustom subjects to a standardized diet of 2500 kcal/day (30% fat) and to establish baseline fecal fat excretion was followed by a 6-day treatment period. Subjects were randomly assigned to one of three treatment groups (A = orlistat 120 mg t.i.d. and ethanol placebo, B = orlistat 120 mg t.i.d. and 40 g ethanol qd on days -1 and 6, and 40 g bid on days 1-5, and C = orlistat placebo tid and 40 g ethanol qd on days -1 and 6, and 40 g b.i.d. on days 1 5). Serial blood samples were collected for determination of ethanol serum concentrations at specified times over 5 h after each dose of ethanol on days -1 and 6, and for determination of orlistat plasma concentrations on days 1, 3, 5, and 6. Feces were collected quantitatively on days -5 through 8 for analysis of fecal fat.

RESULTS

The means of baseline-corrected fecal fat excretion values were comparable: 23.7 g for group A (orlistat) and 22.7 g for group B (orlistat and ethanol). No significant difference was found regarding ethanol pharmacokinetic parameters between treatments with orlistat and placebo. No apparent differences existed between the number of plasma samples with measurable orlistat concentrations in groups A and B.

CONCLUSION

Concomitant ingestion of social amounts of ethanol did not alter the inhibitory effect of orlistat on dietary fat absorption during short-term treatment (6 days) with orlistat. Short-term treatment with orlistat had no significant influence on ethanol pharmacokinetics.

[Effects of l-stepholidine on the peripheral vascular dopamine DA1 and DA2 receptor subtypes]

The effects of l-stepholidine(l-SPD) on peripheral vascular dopamine DA1 and DA2 receptors were studied using isolated vascular rings in rabbits. It was shown that (1) l-SPD(0.1-10 mumol.L-1) shifted the dose-response curves to the right in a nonparallel fashion and decreased the maximal response (Emax) of both the fenoldopam(FODA, a selective DA1 agonist)-induced and the propyl-buty-dopamine(PBDA, a selective DA2 agonist)-induced vasorelaxation showing a non-competitive antagonistic action. The pD2 values of l-SPD for FODA in the renal, pulmonary and mesenteric arteries were 5.43, 5.48 and 5.58, respectively. The pD2 values for PBDA in the mesenteric and femoral arteries were 5.35 and 5.89, respectively. The potencies of its antagonistic action were comparable to SCH23390, a selective DA1 antagonist, and to domperidone, a selective DA2 antagonist. (2) l-SPD(0.1-100 mumol.L-1) per se was also found to induce slight but dose-related vasorelaxations in the renal and pulmonary arteries displaying its DA1 agonistic activity. Its pD2 values were 4.98 and 5.02, respectively. However, its Emax were considerably smaller than that of FODA. These results suggest that l-SPD is a mixed peripheral DA1 and DA2 receptor antagonists and weak DA1 receptor agonist with pharmacological property of dual action.

Pharmacokinetics of recombinant human interferon-alpha 2a combined with 5-fluorouracil in patients with advanced colorectal carcinoma

We evaluated the pharmacokinetics of 5-fluorouracil (5-FU) combined with recombinant human interferon (IFN)-alpha 2a in 10 previously untreated patients with advanced colorectal carcinoma. 5-FU was administered as a continuous i.v. infusion, 750 mg/m2/day for 5 days during week 1. One s.c. injection of IFN-alpha 2a, 9 x 10(6) IU, was administered during week 2. Beginning with week 3, a continuous i.v. infusion of 5-FU 750 mg/m2/day for 5 days was administered in combination with IFN-alpha 2a, 9 x 10(6) IU s.c. three times per week. The combination of 5-FU and IFN-alpha 2a was continued every other week until either 3 months after complete remission or tumor progression. No grade 4 toxicity was observed. Granulocytopenia (two patients), leukopenia (one patient), thrombocytopenia (one patient), stomatitis (two patients), fatigue (one patient) and hand-foot syndrome (one patient) were the major (grade 3) toxic reactions encountered. Overall, one complete and six partial responses were noted. The results of the paired t-test showed no statistically significant differences between the means of the two treatments, 5-FU and 5-FU plus IFN-alpha 2a, with respect to the steady-state plasma concentration, area under the concentration-time curve, total body clearance, or steady-state volume of distribution of 5-FU, or the serum concentration of IFN. We conclude that 5-FU and IFN-alpha 2a do not interact pharmacokinetically at the doses and schedules in the regimen studied.

In vitro and in vivo characterization of three major dadAX promoters in Escherichia coli that are regulated by cyclic AMP-CRP and Lrp

We have shown previously that the dadAX operon of Escherichia coli expresses multiple transcripts, which are repressed by leucine-responsive regulatory protein (Lrp). Here we used site-directed mutagenesis and in vitro and in vivo transcription assays to show that each of the three major dad transcripts requires a specific promoter. These promoters, P1-P3, overlap and are positively regulated in vivo by cyclic AMP-CRP. DNase I footprinting experiments localized two CRP binding sites in this region: CRP1, which is positioned upstream of P1-P3, and CRP2, which is located within the promoters. Site-directed mutagenesis of each site provided evidence that CRP1 is necessary for the effects of cyclic AMP-CRP on dad expression in vivo and in vitro, and that CRP2 probably plays little or no role in this process.

Lrp is a direct repressor of the dad operon in Escherichia coli

Expression of the degradative D-amino acid dehydrogenase (dad) operon is known to be increased when Escherichia coli is grown in the presence of D- or L-alanine. Alanine is thought to act as an inducer to block the action of a postulated repressor. This operon is also believed to be regulated by catabolite repression. We have used in vivo and in vitro experiments that show that the dad repressor is the leucine-responsive regulatory protein (Lrp). dad expression in a dad-lacZ operon fusion strain was increased four- to sevenfold when cells were grown in minimal medium containing alanine or leucine. A strain lacking Lrp had high-level constitutive dad expression. Gel retardation and footprinting studies revealed that Lrp binds in vitro to multiple sites over a large area in the dad promoter region. This binding was reduced by alanine or leucine. In vitro transcription assays, using a plasmid template and primer extension analysis, identified three major dad transcripts (Tr1, Tr2, and Tr3). The formation of these transcripts was differentially regulated by cyclic AMP-cyclic AMP receptor protein complex, and each was strongly repressed by Lrp. Alanine or leucine completely (for Tr1 and Tr2) or partially (for Tr3) reversed Lrp inhibition. Site-directed mutagenesis of an Lrp binding site strongly reduced Lrp binding and prevented Lrp repression of dad transcription in vivo and in vitro. Taken together, these results strongly suggest that Lrp and alanine or leucine act directly to repress and induce, respectively, transcription of the dad operon.

Metabolic profiles of minimally absorbed orlistat in obese/overweight volunteers

To determine the metabolic profile of minimally absorbed orlistat in obese/overweight patients, an open-label, single-dose study was performed in eight obese/overweight volunteers between 23 and 68 years of age. Each subject received a single oral dose of 360 mg orlistat containing approximately 400 muCi of 14C-labeled orlistat. Serial blood samples were collected at specified times over 10 hours after administration of orlistat for determination of total radioactivity, unchanged orlistat, and major metabolites in the plasma. Urine samples were collected over 24 hours and analyzed to evaluate the urinary recovery of total radioactivity and the profile of orlistat metabolites in the urine. In addition, all fecal samples were collected and analyzed for total radioactivity. Urinary and fecal recovery of the administered dose of total radioactivity were 1.13 +/- 0.50% (24-hour data only) and 96.4 +/- 18.1% (n = 7), respectively. Maximum observed concentration (Cmax) and time to Cmax (tmax) values of plasma total radioactivity were 150 +/- 51 ng.eq/mL and 6.8 +/- 1.5 hrs, respectively. All these parameters obtained in obese/ overweight subjects were similar to those reported previously in healthy subjects. On the basis of the area under the concentration-time curve from 0 to 10 hours (AUC0-10), two major metabolites comprise a total of approximately 42% of the total radioactivity in plasma. The primary metabolite (M1) has a short half-life (approximately 2 hours), whereas the secondary metabolite (M3) disappeared at a slower rate. No strikingly apparent difference in the urinary metabolic profile was observed between two gender groups. It is concluded that the disposition of orlistat appears to be similar between normal and obese/overweight subjects. Of the minimal fraction of the dose that was absorbed systemically, the presence of two major metabolites accounts for approximately 42%.

The effect of orlistat, an inhibitor of dietary fat absorption, on the absorption of vitamins A and E in healthy volunteers

An open-label, placebo-controlled, randomized, two-way crossover study was performed in 12 healthy volunteers (between 20 and 44 years of age) to assess the effect of orlistat, a gastrointestinal lipase inhibitor that reduces dietary fat absorption and is being developed for weight control in obesity, on the absorption of vitamins A and E. Each participant received a single oral dose of 25,000 IU vitamin A followed 24 hours later by a single oral dose of 400 IU vitamin E on two separate occasions: during oral administration of 120 mg orlistat or placebo three times daily for 9 days. The two treatments were separated by a washout period of at least 2 weeks. Serial blood samples for pharmacokinetic analysis were collected at specified times over 24 hours after each dose of vitamin A for determination of serum concentrations of retinol, and over a period of 5 days after each dose of vitamin E for determination of serum concentrations of alpha-tocopherol, total cholesterol, and triglycerides. Orlistat significantly reduced the absorption of vitamin E (approximately 43% according to maximum concentration and approximately 60% according to area under the concentration-time curve), but not that of vitamin A, at the dose levels studied. The results of this study will aid in the implementation of a vitamin supplementation strategy, should vitamin deficiency occur in patients undergoing orlistat therapy.

The effect of orlistat on the pharmacokinetics of phenytoin in healthy volunteers

To assess the effect of an orlistat-induced reduction in dietary fat absorption on the pharmacokinetics of phenytoin, a third-party blind, placebo-controlled, randomized, two-way crossover study was performed in 12 healthy volunteers. Each participant received single 300-mg oral doses of phenytoin administered on the fourth day of treatment with 120 mg orlistat (treatment A) or placebo (treatment B) three times a day for 7 days. The two treatments were separated by a 2-week washout period. Serial blood samples were collected before and up to 96 hours after each dose of phenytoin to determine serum concentrations of phenytoin. The 90% confidence intervals (CI) for the ratio of geometric least-squares means for maximum concentration (Cmax) and area under the concentration-time curve (AUC) and for the difference of arithmetic least-squares means for time of maximum concentration (tmax) and elimination rate constant (lambda z) showed the two treatments of phenytoin to be equal by analysis of variance. An approximately 30% reduction in dietary fat absorption induced by orlistat administered at doses of 120 mg three times daily did not significantly alter the pharmacokinetics of a single 300-mg oral dose of phenytoin in healthy volunteers.

The effect of orlistat on the pharmacokinetics and pharmacodynamics of warfarin in healthy volunteers

To assess the effect of orlistat on the pharmacokinetics and pharmacodynamics of warfarin, a third-party blind, placebo-controlled, randomized, two-way crossover study was performed in 12 healthy volunteers. Each participant received single 30-mg oral doses of racemic warfarin sodium (Coumadin; DuPont Pharma, Wilmington, DE) administered on the eleventh day of treatment with 120 mg orlistat (treatment A) and placebo (treatment B) three times a day for 16 days; the two treatments were separated by a 3-week washout period. Serial blood samples were collected before and at appropriate intervals after each dose of warfarin to determine plasma concentrations of R-warfarin and S-warfarin and blood prothrombin time (PT) and plasma Factor VII concentration. In addition, serum concentrations of vitamin K1 and its epoxide and of osteocalcin and its undercarboxylated form were measured before breakfast on days -7, 1, 4, 6, and 10. Equivalent results between treatments with orlistat and placebo were found with regard to all pharmacokinetic parameters of R- and S-warfarin (except for time to maximum concentration of R-warfarin). Pharmacodynamic parameters of warfarin (PT and Factor VII) and vitamin K nutritional status parameters (ratios of vitamin K1 to vitamin K1 epoxide and undercarboxylated osteocalcin to osteocalcin) also were unaltered by orlistat. Orlistat administered at doses of 120 mg three times daily did not significantly alter the pharmacokinetics and pharmacodynamics of a single 30-mg oral dose of warfarin in healthy volunteers.

Lack of effect of orlistat on the bioavailability of a single dose of nifedipine extended-release tablets (Procardia XL) in healthy volunteers

Orlistat, a lipase inhibitor, reduces dietary fat absorption, and thus could potentially alter the absorption of some concomitantly administered drugs, such as the nifedipine gastrointestinal therapeutic system (GITS). To assess the effect of orlistat on the bioavailability of nifedipine GITS, a third party-blind, placebo-controlled, randomized, two-way crossover study was performed in 18 healthy volunteers. Each participant received single 60-mg oral doses of nifedipine GITS (Procardia XL; Pfizer Labs, New York, NY) on the fourth day of treatment with 120 mg of orlistat or placebo three times a day for 6 days. The two treatments were separated by a washout period of at least 1 week. Serial blood samples were collected before and at appropriate intervals after each nifedipine dose to determine plasma concentrations of nifedipine. The 90% confidence intervals for the ratio of geometric least-square means for maximum concentration (C(max)) and area under the concentration-time curve (AUCo-t) and for the difference of arithmetic least-square means for time to maximum concentration (t(max)) indicate that the bioavailability of nifedipine was not altered by treatment with orlistat. Therapeutic doses of 120 mg of orlistat three times daily do not significantly alter the bioavailability of a single 60-mg oral dose of nifedipine GITS in healthy volunteers.

The effect of orlistat, an inhibitor of dietary fat absorption, on the pharmacokinetics of beta-carotene in healthy volunteers

To assess the influence of orlistat, a lipase inhibitor, on the absorption of beta-carotene, an open-label, parallel, placebo-controlled, randomized, two-way crossover study was performed in 48 healthy volunteers between the ages of 19 and 58 years. Each subject received a single oral dose of 0, 30, 60, or 120 mg beta-carotene (12 subjects per dose level) on the fourth day of treatment with orlistat (120 mg) or placebo 3 times a day for 6 days. The treatments were separated by a washout period of at least 5 weeks. Serial blood samples were collected before and at appropriate intervals after administration of beta-carotene to determine plasma concentrations of unchanged beta-carotene. Short-term (3 to 6 days) treatment with orlistat did not alter endogenous profiles of beta-carotene in plasma. When beta-carotene was given during orlistat treatment, its absorption was reduced by approximately one-third. This reduction was consistent for all three dose levels of beta-carotene studied; however, the results for the 30-mg dose level were subject to greater variability, particularly for area under the concentration-time curve (AUC). It was concluded that two thirds of a supplemental dose of beta-carotene will be absorbed during orlistat treatment; this may be sufficient to achieve physiologic levels of beta-carotene with an appropriate dose of beta-carotene, should supplementation be needed in obese patients who have developed beta-carotene deficiency during therapy with orlistat.

Review of limited systemic absorption of orlistat, a lipase inhibitor, in healthy human volunteers

Orlistat, a lipase inhibitor, acts locally in the gastrointestinal tract. Systemic absorption is not required for its efficacy, but knowledge of the extent of its systemic absorption is important for its safe use in obese patients, the intended target population. Pharmacokinetic screening was carried out by monitoring plasma concentrations of unchanged orlistat in 25 phase 1 studies (including two mass balance studies) in normal and obese healthy volunteers. The results of these studies indicate an extremely low degree of systemic absorption for orlistat when administered with a hypocaloric, well-balanced diet with 20% to 30% of calories derived from fat (50-80 gm). To further characterize the pharmacokinetics and excretion pathways of orlistat, two mass balance studies using 14C-labeled orlistat were conducted. After oral dosing of radiolabeled orlistat with a fatty meal (28-30 gm fat), almost the entire dose was recovered from fecal samples; little was found in plasma and urine. It is concluded that systemic absorption of orlistat is negligible; at a clinically efficacious dose level, orlistat is unlikely to produce systemic lipase inhibition.

The influence of reduced dietary fat absorption induced by orlistat on the pharmacokinetics of digoxin in healthy volunteers

To assess the influence of an orlistat-induced reduction in dietary fat absorption on the pharmacokinetics of digoxin, an open-label, placebo-controlled, randomized, two-way crossover study was performed in 12 healthy volunteers. Each subject received single 0.4-mg doses of digoxin (soft gelatin capsules) administered orally on the fourth day of orlistat (120 mg three times daily for 6 days) and placebo (three times daily for 6 days) treatment, separated by at least an 11-day washout period. Serial blood samples were collected before and at appropriate intervals after each digoxin dose to determine plasma concentrations of unchanged digoxin. The 90% confidence intervals for the ratio of geometric least-squares means (for Cmax, AUC0-48, AUC0-t, and AUC) and for the difference of arithmetic least-squares means (for tmax and lambda z) indicate that the pharmacokinetics of digoxin was not altered by treatment with orlistat. This results suggests that a approximately 30% reduction in dietary fat absorption will not change the efficacy of digoxin in cardiac patients.

The influence of orlistat on the pharmacokinetics and pharmacodynamics of glyburide in healthy volunteers

To assess the influence of orlistat on the pharmacokinetics and pharmacodynamics (the blood glucose-lowering effect) of glyburide, an open-label, placebo-controlled, randomized, two-way crossover study was done in 12 healthy male volunteers. Each subject received single 5-mg oral doses of glyburide (Micronase; The Upjohn Company, Kalamazoo, MI) on the fifth day of treatment with placebo (treatment A) and 80-mg orlistat (treatment B) three times a day for 4 1/3 days; the two treatments were separated by a five-day washout period. Serial blood samples were collected before and at appropriate intervals after each glyburide dose to determine plasma concentrations and blood glucose levels. Values of Cmax and AUC of glyburide showed an equality of the two treatments by the analysis of variance. There was an apparent correlation between blood glucose level and the logarithm of plasma glyburide concentration; this relationship appeared to not be altered when glyburide was administered with orlistat. In conclusion, orlistat administered at doses of 80-mg three times daily does not significantly alter the pharmacokinetics and blood glucose-lowering effect of a single 5-mg oral dose of glyburide in healthy volunteers.

Influence of human serum albumin content in formulations on the bioequivalency of interferon alfa-2a given by subcutaneous injection in healthy male volunteers

To determine the influence of human serum albumin (HSA) content in formulations on the bioequivalency of recombinant interferon alfa-2a, a double-blind, randomized, two-way crossover study was conducted in 24 healthy male volunteers. Subjects received a single subcutaneous injection of 18 million IU of Roferon-A reconstituted with either the diluent containing 10 mg of HSA or the HSA-free diluent; final HSA contents in the 2 formulations were 15 mg and 5 mg, respectively. Administration of the 2 formulations resulted in similar 48-hour Roferon-A serum concentration-time profiles and comparable frequency and intensity of adverse events. The statistical analysis using the two one-sided tests procedure showed that both formulations were bioequivalent for pharmacokinetic parameters such as Cmax, tmax, AUC48, and AUC. We conclude that a threefold change in HSA content in formulations does not alter the bioequivalency of Roferon-A.

The pharmacokinetic-pharmacodynamic (Digit Symbol Substitution Test) relationship of flumazenil in a midazolam steady-state model in healthy volunteers

To characterize the plasma concentration-effect relationship of flumazenil in the presence of a predefined midazolam level, a double-blind, placebo-controlled, randomized two-way crossover study was conducted in nine healthy male subjects. After reaching a criterion level of midazolam-induced depression of the Digit Symbol Substitution Test (DSST), volunteers received a dose of flumazenil (1.0 mg) or placebo over 1 minute, with the infusion of midazolam continued. Blood samples were collected, simultaneously with the DSST assessment, at predetermined intervals and were assayed for flumazenil and/or midazolam plasma concentrations. Pharmacokinetic-pharmacodynamic modeling techniques were used to estimate the equilibration rate constant (keo) between plasma concentration and effect for flumazenil; a sigmoidal maximum-effect model was used to relate the DSST score to the flumazenil plasma concentration. Flumazenil exhibited a rapid onset (the half-life of equilibration between drug concentration in the blood and drug effect was 3.3 minutes) and short duration of action (the flumazenil plasma concentration causing half-maximal effect was 7.4 ng/ml, which was reached about 1 hour after dosing). The results of this study also show the competitive nature of flumazenil as a midazolam antagonist.

Retrospective population-based analysis of the dose-response (fecal fat excretion) relationship of orlistat in normal and obese volunteers

Orlistat, an inhibitor of gastrointestinal lipases, limits the absorption of ingested fat and could become a potential treatment for obesity. This analysis was performed to elucidate the relationship between orlistat dose and intensity of inhibition of dietary fat absorption (assessed by measuring fecal fat excretion). In 11 phase I double-blind, placebo-controlled, parallel-group randomized studies, a total of 171 subjects received oral daily doses that ranged from 30 to 1200 mg orlistat or matching placebo three times a day for 9 to 10 days. The results of the daily mean fecal fat excretion percentage (relative to ingested fat) were correlated to the orlistat daily dose. A simple maximum-effect model that included a basal value was used to fit the dose-response relationship for all evaluable subjects. The mean maximum percentage of ingested fat excreted in the feces was approximately 32% during orlistat administration compared with 5% during placebo administration. The orlistat daily dose that produced 50% of the maximum effect was 98 mg/day. The model-fitting suggests the existence of a steep portion of the dose-response curve up to approximately 400 mg/day, with a subsequent tendency to plateau at higher doses. Such an analysis was instrumental in identifying appropriate doses to be used in therapeutic trials for weight loss in obese patients.

Penetration of fleroxacin and ciprofloxacin into skin blister fluid: a comparative study

The penetration of multiple-dose concentrations of oral fleroxacin (400 mg every 24 h) and ciprofloxacin (500 mg every 12 h) into skin blister fluid in 12 healthy volunteers was determined in a randomized crossover study. Serum, blister fluid, and paper disk samples were analyzed by large-plate microbiologic assay. The mean areas under the concentration-time curve (AUC) for serum were 88.6 and 18.2 micrograms.h/ml/70 kg for fleroxacin and ciprofloxacin, respectively. The mean AUC for blister fluid and paper disks were 71.2 and 15.0 micrograms.h/ml/70 kg and 77.8 and 15.4 micrograms.h/ml/70 kg for fleroxacin and ciprofloxacin, respectively. Calculated penetration into interstitial fluid ranged from 74 to 92% for fleroxacin and 56 to 96% for ciprofloxacin; penetration was calculated by using the ratio of maximum drug concentration or AUC in blister fluid and paper disks to maximum drug concentration or AUC in serum. There was no significant difference between fleroxacin and ciprofloxacin in the percent penetration into skin blister fluid.

Optimization of the therapeutic index by adjustment of the rate of drug administration or use of drug combinations: exploratory studies of diuretics

The purpose of this investigation was to explore theoretically certain strategies for optimizing the therapeutic index of drugs and to assess these strategies experimentally with two diuretics. Diuretic agents allow dosing rate flexibilities because the temporal profile of diuretic action can vary considerably as long as the total diuretic effect per day is the same. They can also be used in combination. Experiments were designed to determine if the therapeutic index of furosemide and hydrochlorothiazide can be optimized by administering one or the other at a certain rate or by administering the two drugs together in a certain ratio and at a certain rate. Male Lewis rats received one or the other drug, or combinations of the two, by i.v. infusion at different rates. Several timed urine collections were made under steady-state conditions, with excreted urine replaced volume for volume by i.v. lactated Ringer's solution. The urine flow rates and the urinary excretion rates of the diuretics and of Na+ and K+ were determined. The relationship between the diuretic effect of either of the two drugs given alone and the respective drug excretion rate could be described by the Hill equation. The ratio of urine flow rate to K+ excretion rate exhibited a marked dependence on hydrochlorothiazide excretion rate (highest ratio at high excretion rates), whereas the K+/Na+ excretion rate ratio was constant over a wide range of hydrochlorothiazide excretion rates. There was no significant change of these ratios with changing excretion rate of furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)

A pharmacodynamic model for the activity of antibiotics against microorganisms under nonsaturable conditions

An exact mathematical solution was derived to a pharmacodynamic model which illustrates bacterial survival in the presence of antibiotics. In this report the survival of Pseudomonas aeruginosa in the medium of an initial concentration of 0.64 mM (320 mg/L) of piperacillin [(2S,5R,6R)-6-[(R)-2-(4-ethyl-2,3-dioxo-1- piperazinecarboxyamido)-2-phenylacetamido]-3,3-dimethyl-7- oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate] was well described by the derived model for up to 24 h. The bacterial killing by the antibiotic and apparent natural growth rate constants were 2955.3 h-1 X mol-1 and 0.5698 h-1, respectively. The functional equation was also fit to the data of ampicillin against Escherichia coli under simulated in vivo conditions. The optimal multiple dosing time and the minimum critical concentration to achieve antimicrobial action can be readily calculated from the developed model. Computer simulations were made to examine the effect on microbial survival of such factors as initial antibiotic concentration (Co), elimination half-life (t1/2), kill rate constant (K) of the antibiotic, and apparent growth rate constant (Kapp) of the test organism.