Anthropometric measures and their association with risk factors for cardio-metabolic diseases in Kenyan adults.

BACKGROUND: The prevalence of cardio-metabolic diseases (CMD) is drastically increasing worldwide. Anthropometric measures of fat accumulation are correlated with CMD and Metabolic Syndrome (MS), but few studies have addressed this association in sub-Saharan African populations. AIM: To investigate the association between anthropometric features, MS and other CMD risk factors in a population from Kenya. SUBJECTS AND METHODS: In this cross-sectional study including 1405 Kenyans, anthropometric measurements including visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (SAT) were carried out. Fasting blood glucose and standard oral glucose tolerance test, fasting serum insulin and plasma lipids were analysed. Homeostatic model assessment of insulin resistance was calculated. Systolic and diastolic blood pressures were measured. RESULTS: CMD risk factors and MS were associated with all anthropometric features, except for high-density lipoprotein cholesterol levels (p < 0.05). The strongest association between MS and anthropometrics was seen with SAT (ß = 1.45 ± 0.32 in men and 0.88 ± 0.14 in women, both p < 0.05). CONCLUSIONS: Anthropometric measures, especially features of central obesity such as VAT and SAT, are relevant indicators of cardio-metabolic health in Kenyan populations. SAT is the strongest predictor of MS. These results highlight the need for further research on the pathological implication of VAT and SAT, in order to understand patterns of fat distribution and cardio-metabolic health among different ethnic groups.

A multicentre open-label safety and efficacy study of tetrodotoxin for cancer pain.

BACKGROUND: Cancer pain is highly prevalent, and existing treatments are often insufficient to provide adequate relief. OBJECTIVES: We assessed the long-term safety and efficacy of subcutaneous tetrodotoxin treatment in reducing the intensity of chronic cancer-related pain. METHODS: In this multicentre open-label longitudinal trial, 30 µg tetrodotoxin was administered subcutaneously twice daily for 4 days in a heterogeneous cohort of patients with persistent pain despite opioids and other analgesics. "Responder" was defined as a mean reduction of 30% or more in pain intensity from baseline; and "clinical responder" as some pain reduction, but less than 30%, plus agreement on the part of both the patient and the physician that a meaningful analgesic response to treatment had occurred. RESULTS: Of 45 patients who entered the longitudinal trial, 41 had sufficient data for analysis. Of all 45 patients, 21 (47%) met the criteria for "responder" [16 patients (36%)] or "clinical responder" [5 patients (11%)]. Onset of pain relief was typically cumulative over days, and after administration ended, the analgesic effect subsided over the course of a few weeks. No evidence of loss of analgesic effect was observed during subsequent treatments (2526 patient-days in total and a maximum of 400 days in 1 patient). One patient withdrew from the study because of adverse events. Toxicity was usually mild (82%) or moderate (13%), and remained so through subsequent treatment cycles, with no evidence of cumulative toxicity or tolerance. CONCLUSIONS: Long-term treatment with tetrodotoxin is associated with acceptable toxicity and, in a substantial minority of patients, resulted in a sustained analgesic effect. Further study of tetrodotoxin for moderate-to-severe cancer pain is warranted.

Modulation of inflammation by chondroitin sulfate.

OBJECTIVE AND METHODS: To evaluate the immune-modulator effect of chondroitin sulfate (CS) by means of the review of the literature. RESULTS: Inflammatory reactions are primarily originated by infectious agents, immune reactions and by sterile tissue lesions that activate membrane receptors by means of pathogen-associated molecular patterns, tissue breakdown products and cytokines. The activation of membrane receptors triggers the phosphorylation of mitogen activated protein kinases and of the nuclear factor kappaB (NF-kappaB). The binding of NF-kappaB to the promoter of target genes enhances the expression of pro-inflammatory cytokines, inducible nitric oxide synthase, cyclooxygenase 2, phospholipase A2, and matrix metalloproteases, proteins that contribute to tissue damage and to the inflammatory reaction. The activation of NF-kappaB has a key role in the immune homeostasis and the inflammatory response and therefore, in the pathogenesis of numerous diseases. Chondroitin sulfate (CS) is able to diminish NF-kappaB activation and nuclear translocation in chondrocytes and synovial membrane, effects that may explain the benefits of CS in osteoarthritis. In addition, systemic CS reduces NF-kappaB nuclear translocation in macrophages and hepatocytes, raising the hypothesis that CS might be of benefit to treat other diseases with a strong inflammatory component. There is preliminary evidence in humans that CS improves moderate to severe psoriasis. Moreover, experimental and clinical data suggest that CS might be a useful therapeutic agent in diseases such as inflammatory bowel diseases, atherosclerosis, Parkinson's and Alzheimer's diseases, multiple sclerosis, amyotrophic lateral sclerosis, rheumatoid arthritis and systemic lupus erythematosus. DISCUSSION: These results urge for double blinded placebo-controlled trials to confirm the utility of CS in diseases with immune and inflammatory components.

Anti-inflammatory activity of chondroitin sulfate.

Osteoarthritis is primarily characterized by areas of destruction of articular cartilage and by synovitis. Articular damage and synovitis are secondary to local increase of pro-inflammatory cytokines (interleukin-1beta and tumor necrosis factor-alpha), enzymes with proteolytic activity (matrix metalloproteinases), and enzymes with pro-inflammatory activity (cyclooxygenase-2 and nitric oxide synthase-2). Enhanced expression of these proteins in chondrocytes and in synovial membrane appears associated to the activation and nuclear translocation of nuclear factor-kappaB (NF-kappaB). Chondroitin sulfate (CS) prevents joint space narrowing and reduces joint swelling and effusion. To produce these effects, CS elicits an anti-inflammatory effect at the chondral and synovial levels. CS and its disaccharides reduce NF-kappaB nuclear translocation, probably by diminishing extracellular signal-regulated kinase1/2, p38mitogen-activated protein kinase and c-Jun N-terminal kinase activation. This review discusses the evidence supporting that CS pleiotropic effects in chondrocytes and synoviocytes are primarily due to a common mechanism, e.g., the inhibition of NF-kappaB nuclear translocation.

Effect of hypoxia on cytochrome P450 activity and expression.

In the last three decades, numerous reports have shown that patients with chronic pulmonary disease and with heart failure with hypoxemia cleared drugs at a lower rate than healthy volunteers. As a consequence decreased clearance, drug toxicity is frequent in these patients. The reduction in drug clearance is due to a decrease in activity of cytochrome P450 isoforms, partly associated to the hypoxemia. With in vivo animal models, acute moderate hypoxia (PaO2 of around 35-50 mm Hg) reduces the clearance of drugs biotransformed by CYP1A1, CYP1A2, CYP2B6, CYP2C9, CYP2C19 and CYP2E1, although hypoxia does not affect the clearance of drugs biotransformed by CYP3A6. Ex vivo and in vitro experiments demonstrate that hypoxia down-regulates CYP1A1, CYP1A2, CYP2B6, CYP2C9 and CYP2C19, decrease preceded by a reduction in activity. On the other hand, acute moderate hypoxia up-regulates CYP3A6. The changes in protein expression are preceded by modifications in the mRNA coding for the proteins. The effect of hypoxia on hepatic cytochrome P450 is carried out by serum mediators, e.g. interferon-gamma, interleukin-1beta, and interleukin-2 are responsible for the decrease in activity and in expression of cytochrome P450 isoforms, and erythropoietin accounts for the increase in CYP3A6. Probably several mechanisms underlie and contribute to the decrease in activity and down-regulation of cytochrome P450 isoforms by hypoxia, e.g. reducing potentiation factors, inducing repressor elements and activating negative regulatory elements. The up-regulation of CYP3A6 implies a PTK- and p42/44MAPK-dependent stabilization/activation, nuclear translocation of HIF-1 and AP-1, binding to CYP3A6 promoter, and transactivation of the gene to induce CYP3A6 expression.

In human therapy, is the drug-drug interaction or the adverse drug reaction the issue?

In recent years, many publications in scientific journals have reported, in healthy volunteers, potential food-drug or drug-drug interactions. The lay press has frequently emphasized such interactions and extrapolated on the dangers of food-drug or drug-drug interactions. However, the clinical relevancy of these interactions has not always been substantiated in patients. The aim of the present review was to assess the clinical relevancy of drug-drug interactions occurring at the level of the biotransformation of the drug. For this purpose, the incidence of serious, life-threatening adverse drug reactions (ADRs) of drugs metabolized by different enzymes of cytochrome P450 found in the safety reports issued in megatrials were compared with those from placebo trials. It was concluded that serious ADRs secondary to drug-drug interactions are infrequent; drug-drug interactions including selected drugs with a narrow therapeutic index and eliciting life-threatening undesired effects occur; and serious ADRs secondary to drug-drug interactions are most frequent in elderly patients, in the presence of polypharmacy, in the psychiatric patient population, and in the presence of inappropriate prescriptions and of multiple prescriptors.

L-NAME prevents in vivo the inactivation but not the down-regulation of hepatic cytochrome P450 caused by an acute inflammatory reaction.

A turpentine-induced inflammatory reaction (TIIR) down-regulates multiple isoforms of hepatic cytochrome P450 (P450) and increases microsomal lipid peroxidation. Since the synthesis of nitric oxide (NO*) is stimulated by inflammatory reactions, and NO* can depress the P450, it was of interest to investigate in vivo whether L-NAME and theophylline, by its anti-inflammatory properties, could prevent the depression of P450 caused by a TIIR. Control and rabbits with a TIIR received L-NAME for 72 h, and the activity of P450 was assessed in vivo and in vitro. In vivo, TIIR reduced theophylline systemic clearance by 50% (p<0.05), P450 total content by 67%, and the amount of CYP1A1/2 proteins by around 60% (p<0.05). L-NAME partially prevented the decrease in theophylline systemic clearance and in P450 total content, as well as the increase in lipid peroxidation; however, L-NAME did not hinder CYP1A1/2 proteins down-regulation. L-NAME did not modify the in vitro ability of the serum of rabbits with TIIR to decrease P450 activity, suggesting that the effect of L-NAME is not associated to a decrease in serum mediators. As assessed by the concentration in seromucoids, theophylline did not modify the severity of the inflammatory reaction, nor did it prevent the decrease in P450 activity. In conclusion, a TIIR down-regulates and reduces P450 activity, decrease that is at least in part mediated by NO*; theophylline does not prevent TIIR-induced P450 decrease in activity.

Permeability of the peptidic GH secretagogues hexarelin and EP 51389, across rat jejunum.

The intestinal permeability of hexarelin and EP 51389, two growth hormone releasing hexa- and tri- peptide analogues, was assessed in vitro with side-by-side diffusion chambers in the apical-to-basolateral (AP-to-BL) and in the basolateral-to-apical (BL-to-AP) direction using excised rat jejunal segments. The effect of EP 51389 on P-glycoprotein (P-gp) was evaluated by rhodamine 123 accumulation on monolayers of CH(R)C5 cells with increasing concentrations of EP 51389. Hexarelin and EP 51389 permeability were found to be < 1%. Permeability coefficients (P(app)) were 18.87 +/- 2.86 (x10(-7) cm/s) and 5.87 +/- 0.45 (x10(-7) cm/s) for hexarelin and EP 51389, respectively. Bidirectional studies revealed that hexarelin transport was similar in both directions. EDTA did not influence hexarelin permeability. Permeability was predominantly secretory for EP 51389 as P(app) in the BL-to-AP direction [32.56 +/- 6.11 (x10(-7) cm/s)] was greater than AP-to-BL. Confirming involvement of a secretory transport system, chlorpromazine inhibited EP 51389 transport across the jejunum. EP 51389 inhibited P-gp in a dose dependent manner resulting in the intracellular accumulation of rhodamine in CH(R)C5 cells. These results suggest that: 1) the intestinal permeability of hexarelin and EP 51389 is poor; 2) the passage of hexarelin is mainly via a transcellular passive pathway since the contribution of paracellular permeability to the overall permeability is rather low; 3) P-gp may act as a potential barrier for the intestinal absorption of EP 51389.

Cytochrome P450 down-regulation by serum from humans with a viral infection and from rabbits with an inflammatory reaction.

Serum from humans with an upper respiratory viral infection (HS(URVI)) and from rabbits with a turpentine-induced acute inflammatory reaction (RS(TIAR)) reduces the activity of hepatic cytochrome P450 (P450) following 4 h of incubation. The aim of the present study was to assess the effect of HS(URVI) and RS(TIAR) on P450 activity and expression following 24 h of incubation with hepatocytes from control (H(CONT)) and rabbits with a TIAR (H(INFLA)). RS(TIAR) incubated with H(CONT) for 24 h reduced P450 content and activity, and CYP3A6 by 45%, without changing CYP1A1 and 1A2; when incubated with H(INFLA), RS(TIAR) decreased P450 content and activity without affecting CYP1A1 or 1A2. HS(URVI) incubated for 4 h with H(CONT) decreased P450 activity without affecting the amounts of CYP1A1, 1A2, or 3A6, although when incubated for 24 h, P450 activity and CYP3A6 amount decreased. HS(URVI) incubated with H(INFLA) for 4 h reduced P450 content and activity, and incubated for 24 h reduced activity, P450 content, and amount of CYP1A1 and 1A2 proteins. The present study demonstrates that 1) the effect of RS(TIAR) and HS(URVI) depends upon the susceptibility of the hepatocyte, i.e., H(CONT) or primed H(INFLA); 2) P450 down-regulation is preceded by a decrease in P450 activity; 3) the nature of the inflammatory reaction determines the repercussions on P450 activity and expression; and 4) CYP3A6 is more vulnerable than CYP1A1 and 1A2 to the down-regulation provoked by an inflammatory challenge.

Pharmacokinetics of morphine and its glucuronidated metabolites in burn injuries.

OBJECTIVE: To investigate the effects of major thermal burn injury and continuous intravenous morphine infusion on the disposition of morphine and its glucuronidated metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) once a week for three weeks. CASE SUMMARIES: Five patients with major first-, second-, or third-degree burn injuries received long-term intravenous morphine infusion. The required dose varied greatly (from 4 to 39.5 mg/h). The steady-state concentrations of morphine, M3G, and M6G ranged from 20 to 452, 29 to 3436, and 20 to 1240 mumol/L, respectively. The systemic clearance (Cls) of morphine ranged from 14.8 to 40.3 mL/min/kg and did not change over time. The ratios of M6G and M3G to morphine were not affected by dose, even with the wide variation of intravenous dosage. Morphine kinetics appeared to be first-order. Mean recovery of morphine, M3G, and M6G in urine was 1.7 +/- 1.0%, 42.0 +/- 16.8%, and 11.8 +/- 3.2%, respectively, and renal clearance ranged from 8 to 64, 26 to 325, and 59 to 589 mL/min, respectively. Mean pain intensity ratings at rest remained low and stable (0.7 +/- 0.9 on day 7, 0.4 +/- 0.3 on day 14, 0 +/- 0 on day 21). DISCUSSION: To our knowledge, this is the first published report describing morphine, M3G, and M6G disposition in patients with major thermal burn injury. The Cls of morphine is similar to that observed in other patient populations and healthy subjects, suggesting that the presence of major burn injuries or a continuous morphine infusion over a three-week period may not contribute significantly to the variability among individuals. In these cases, the renal clearance of morphine and its glucuronides was within the range of values reported for other populations of patients and healthy subjects. Recovery of morphine and its glucuronides in urine was also similar to that in healthy individuals. CONCLUSIONS: These cases suggest that the effects of major burn injuries and of long-term intravenous infusion of morphine did not seem to modify morphine, M3G, and M6G disposition. Among patients with burn injuries, the severity of burns of duration of administration are not a cause of nonlinear kinetic of morphine or of morphine resistance. The morphine infusion rate was substantially variable and not directly related to its clearance, suggesting that monitoring of morphine should be focused on the clinical response.

Role of reactive oxygen intermediates in the decrease of hepatic cytochrome P450 activity by serum of humans and rabbits with an acute inflammatory reaction.

Serum of rabbits with a turpentine-induced acute inflammatory reaction (RS(INFLA)) and serum of humans with a viral infection (HS(INF)) were previously shown to diminish hepatic cytochrome P450 (P450) content and activity. To document the role of reactive oxygen intermediates in the serum-mediated decrease in P450 content and activity, hepatocytes of rabbits with an acute inflammatory reaction (H(INFLA)) were incubated with RS(INFLA) and HS(INF) for 4 h, and total P450 content (spectrally measurable P450), P450 activity (assessed by estimating the formation of theophylline metabolites), and amount of CYP1A1, CYP1A2, and CYP3A6 proteins were measured. RS(INFLA) or HS(INF) decreased P450 content and activity without affecting the amount of CYP1A1 and -1A2 H(INFLA). Exposure of H(CONT) or H(INFLA) to hydrogen peroxide (0.01-1.0 mM) and sodium nitroprusside (0.01-1.0 mM) produced a dose-dependent decrease in P450 content and in the formation of theophylline metabolites without modifying the amount of CYP1A1 and CYP1A2, whereas lipid peroxidation increased. Incubation of L-NAME (0.05-1.0 mM), dimethylthiourea (6.25-50 mM), or N-acetylcysteine (0.01-1.0 mM) with H(INFLA) partially prevented the decrease in P450 content and activity and the increased lipid peroxidation induced by RS(INFLA) and HS(INF). On the other hand, 3-amino-1,2,4-triazole (10-100 mM) or diethyldithiocarbamate (1.0-10 mM) potentiated RS(INFLA)- and HS(INF)-mediated decreases in P450 content and activity and the increase in lipid peroxidation, without affecting the amount of CYP1A1 or -1A2; DL-buthionine-(S,R)-sulfoximine (2.5-25 mM) potentiated only the inhibition of 1,3-dimethyluric acid formation. It is concluded that reactive oxygen intermediates are implicated in the decrease of H(INFLA) P450 content and activity induced by 4 h of exposure to RS(INFLA) or HS(INF).

Cytochrome P450 inactivation by serum from humans with a viral infection and serum from rabbits with a turpentine-induced inflammation: the role of cytokines.

Serum from humans with an acute upper respiratory viral infection and from rabbits with turpentine-induced inflammation reduce the catalytic activity of hepatic cytochrome P450 (P450). The aim of this study was to identify the serum mediators responsible for the decrease in P450 activity. Rabbit and human sera were fractionated by size exclusion chromatography and the fractions tested for their ability to reduce the activity and amount of P450 after 4 h of incubation with hepatocytes from turpentine-treated rabbits (H(INF)). Rabbit and human sera decreased P450 activity by around 40% without any change in the amount of CYP1A1 and 1A2 apoproteins. In rabbit serum, the fraction containing proteins of M(r) 23-15 kDa decreased P450 content by 41%, but did not alter the amount of the apoproteins. Anti-IL-6 antibody added to the M(r) 23-15 kDa fraction restored P450 content to 97% of control values, while anti-IL-1beta, TNF-alpha and IFN-gamma antibodies had no effect. Supporting the role of IL-6, incubation of H(INF) in the presence of IL-6 for 4 h reduced P450 content by 40%. In human serum, the fraction containing proteins of M(r) >95 kDa lowered P450 content by 43% without modifying the amounts of CYP1A1/2. Neutralization experiments showed that IFN-gamma, IL-6, and IL-1beta contributed to the decrease in P450 content. In conclusion, the present results demonstrate that IL-6, and IFN-gamma, IL-6 and IL-1beta are the serum mediators released in vivo by a turpentine-induced inflammatory reaction in the rabbit and an upper respiratory viral infection in humans, respectively, inactivating hepatic P450.

Hypoxemia modifies circulating and exudate neutrophil number and functional responses in carrageenin-induced pleurisy in the rat.

To assess the effect of hypoxemia on the responses of polymorphonuclear neutrophils (PMN) during an inflammatory response, rats were maintained in a low F1O2 atmosphere (9% O2) or room air for 12 h before intrathoracic injection of carrageenin or intradermal injections of agonists. After 4 h, hypoxemic rats had 50% more circulating PMN in blood and 25% less PMN in pleural exudate, whereas the number of PMN in skin biopsies did not differ from controls. Following hypoxemia, basal adhesion of blood PMN to serum-coated plastic wells was unchanged, whereas fMLP-stimulated adhesion was 50% greater. In contrast, basal adhesion of exudate PMN was 72% greater. In hypoxemic rats, exudate PMN produced 64% more PMA-stimulated superoxide than blood PMN; furthermore, blood and exudate PMN produced 4.5- and 2-fold more LPS-stimulated nitric oxide than controls, respectively. These results show that a moderate level of hypoxemia may trigger mechanisms that will interfere with PMN emigration yet prime these cells for enhanced responses upon stimulation.

Nonlinear kinetics and pharmacologic response to mibefradil.

BACKGROUND: Increasing oral doses of mibefradil (10 to 320 mg) decrease its apparent oral clearance; however, intravenous doses up to 80 mg do not reduce its systemic clearance. This study aimed to understand the mechanisms underlying the zero-order kinetics of mibefradil. METHODS: A group of 10 normotensive volunteers received 50 mg/day oral mibefradil for 8 days and, on days 1 and 8, 5 mg deuterated mibefradil by infusion. Ten additional volunteers observed the same protocol with a daily oral dose of 100 mg mibefradil. Serial blood samples were withdrawn, and mibefradil plasma concentrations were assayed by liquid chromatography-mass spectrometry. Blood pressure and heart rate were measured for 4 hours, and an ECG was performed 2 hours after drug administration. RESULTS: Repeated oral administration of 50 mg mibefradil generated zero-order kinetics secondary to a decrease in mibefradil systemic clearance. Compared with the 50-mg dose, single and repeated oral doses of 100 mg further decreased mibefradil clearance. Mibefradil bioavailability was not affected by increasing mibefradil doses. Mean diastolic blood pressure was decreased by single and repeated doses of 100 mg to the same extent. Repeated doses of 100 mg reduced heart rate and prolonged the PR and QTc, changes that were associated with mibefradil plasma concentrations. CONCLUSIONS: Repeated doses of 50 mg or doses of 100 mg mibefradil generated zero-order kinetics secondary to a decrease in hepatic extraction of the drug. Zero-order kinetics did not affect the response-concentration relationship of mibefradil.

Input rate as a major determinant of furosemide pharmacodynamics: influence of fluid replacement and hypoalbuminemia.

To investigate how the response to a bolus and an infusion of furosemide is modulated by the rate of fluid replacement and by hypoalbuminemia, rabbits received 5 mg/kg of furosemide as a bolus or infused over 60 min, whereas diuresis was replaced with 13, 121, or 238 ml/h NaCl 0.9%/glucose 5% (50:50). Natriuretic and diuretic efficiencies were greater with the infusion than with the bolus of furosemide. Fluid replacement increased natriuretic and diuretic efficiency of furosemide bolus but only diuretic efficiency of furosemide infusion. Furosemide net fluid depletion reached a plateau when fluid replacement increased beyond 121 ml/h. Repeated plasmapheresis decreased plasma albumin by 30% (P <.05) and increased furosemide unbound fraction (P <.05). Compared with control rabbits, hypoalbuminemia decreased the natriuresis of the bolus (22.7 +/- 1.5-16.6 +/- 1.3 mmol, P <.05) but not that elicited by furosemide infusion (26.2 +/- 1.8 mmol). Given as a bolus, furosemide natriuretic and diuretic response as a function of its urinary rate of excretion exhibited an hyperbolic relationship, and after its infusion a clockwise hysteresis, denoting tolerance. Plasma renin activity was increased by the bolus and the infusion of furosemide, even in the presence of 121 ml/h of fluid replacement. It is concluded that: 1) the increase in natriuretic/diuretic efficiency of the bolus induced by fluid replacement is greater than when furosemide is infused, 2) furosemide net effect does not increase proportionally to fluid replacement, and 3) the infusion of furosemide prevents the hypoalbuminemia-induced decrease in response of furosemide given as a bolus.

Kinetics and disposition of hexarelin, a peptidic growth hormone secretagogue, in rats.

To document the disposition of hexarelin, a peptidyl growth hormone secretagogue, male Sprague-Dawley rats received a 5-microg/kg bolus i.v. dose or three single s.c. doses of 5, 10, and 50 microg/kg. To assess hexarelin tissue distribution and excretion, rats were given 1 microg/kg of [(3)H]hexarelin (9.4 Ci/mmol). Metabolism of [(3)H]hexarelin was assessed in bile duct-exteriorized rats given 50 microg/kg where radiolabeled hexarelin biliary and urinary excretion was quantified. After its i.v. injection, hexarelin displayed a half-life of 75.9 +/- 9.3 min, a systemic clearance of 7.6 +/- 0.7 ml/min/kg, and a volume of distribution at steady state of 744 +/- 81 ml/kg. After s.c. administration, the area under the curve (477-3826 pmol.min/ml) estimated with increasing doses confirmed the absence of hexarelin accumulation. Clearance/F (12-15 ml/min/kg) and volume of distribution/F (1208-1222 ml/kg) were dose independent. Hexarelin bioavailability given s.c. was 64%. The highest radioactivity levels were detected in the kidney, liver, and duodenum. The pattern of hexarelin excretion was similar after i.v. or s.c. administrations. Total radioactivity in bile, urine, and feces corresponded to 60, 22, and 10% of the dose, respectively. Of the radioactivity excreted in bile and urine, 90 and 71% was unchanged hexarelin, respectively. These results suggest that: 1) the kinetics of hexarelin appear to be first order up to 50 microg/kg; 2) hexarelin is rapidly absorbed after s.c. administration; 3) biliary excretion is the primary route of hexarelin elimination; and 4) the high recovery of unchanged peptide in bile and urine demonstrates hexarelin stability toward proteolytic enzymes.

Acute moderate hypoxia reduces ethanol elimination in the conscious rabbit.

Hypoxic states decrease the catalytic activity of certain enzymes of the cytochrome P450, leading to decreased clearance of selected xenobiotics. It is not known whether hypoxia can affect the activity of cytosolic enzymes such as liver alcohol dehydrogenase (LADH). This study was carried out to examine the effect of experimentally induced acute moderate hypoxia on the kinetics of ethanol and on the catalytic activity of LADH in the conscious rabbit. To this purpose, the kinetics of elimination of ethanol (70 mg/kg intravenously) were studied in male rabbits (n = 6) kept in an atmosphere with a fractional concentration of O2 (FiO2) of 0.12 for 24 h, and in rabbits (n = 6) breathing room air with a FiO2 approximately 0.21 (controls). Compared with controls, the clearance of ethanol was reduced by 32% (P < 0.05) in rabbits exposed to acute moderate hypoxia. In rabbits that consumed approximately 6 g/kg/day ethanol in their drinking water for 14 days (n = 6), acute moderate hypoxia reduced the clearance of ethanol to the same extent as observed in rabbits receiving a single dose of ethanol. Hypoxia did not change the in vitro Vmax or Km of LADH. This study demonstrates that acute moderate hypoxia reduces the clearance of ethanol following single or multiple administrations.

Cytochrome P-450 content and activity after cold storage of rat hepatocytes in university of wisconsin and sodium-lactobionate-sucrose solutions.

We compared the capacity of University of Wisconsin (UW) and of sodium-lactobionate-sucrose (SLS) hypothermic preservation solutions to maintain the integrity of the hepatic cytochrome P-450-dependent mono-oxygenase system. Isolated rat hepatocytes were stored for 0, 10, 24, and 48 hours in UW or SLS solution and were subsequently cultured shortly at 37 degrees C. Cell viability declined slightly but significantly in a time-dependent manner during cold preservation in either UW or SLS solution, and warm culture exacerbated this effect. Total cytochrome P-450 declined gradually after cold preservation and warm culture to reach values of 70% and 52% of unstored controls in cells preserved for 24 and 48 hours in cold UW solution, respectively. Storage in cold SLS solution yielded a similar decrease to 79% and 59% of unstored controls for the equivalent preservation times. Cytochrome P-450 activity was assessed by the metabolism of theophylline after various cold preservation times in UW or SLS solutions. Production of the major metabolite 1,3-dimethyluric acid was not significantly affected by extended cold preservation periods in either UW or SLS solutions. Similarly, the amount of residual theophylline remained stable in all groups, suggesting that alternative metabolic routes were not modified. These studies show that cold preservation in SLS solution is as effective as that in UW solution in terms of cell viability, cytochrome P-450 content, and activity toward theophylline. In addition, the significant reduction in cytochrome P-450 in conjunction with unaffected theophylline disposition suggests that certain cytochrome P-450 isoforms are specifically damaged by cold preservation and rewarming.