Developmental plasticity of the carotid chemoafferent pathway in rats that are hypoxic during the prenatal period.

The chemoreflex pathway undergoes postnatal maturation, and the perinatal environment plays a critical role in shaping respiratory control system. We investigated the role of prenatal hypoxia on the maturation of the chemoreflex neural circuits regulating ventilation in rat. Effects of hypoxia (10% O2) from the 5th to the 20th day of gestation were studied on male offspring at birth and on postnatal days 3, 7, 21 and 68. Maturation of the respiratory control system was assessed by in vivo tyrosine hydroxylase (TH) activity measurement in peripheral chemoreceptors (carotid bodies, petrosal ganglia), and in brainstem catecholaminergic cell groups (A2C2c and A1C1 areas in the medulla, A5 and A6 areas in the pons). Resting ventilation and ventilatory response to hypoxia were evaluated as functional sequelae. In peripheral structures, prenatal hypoxia reduced TH activity within the first postnatal week and enhanced it later. In contrast, in central areas, prenatal hypoxia upregulated TH activity within the first postnatal week and downregulated it later. The in vivo TH activity impairment is therefore tissue specific, with an opposite effect on the peripheral and central neural circuits. A shift of the effect of prenatal hypoxia occurred between 1 and 3 weeks, indicating a postnatal temporal effect of prenatal hypoxia. An important period in the development of the chemoafferent pathway occurred between the first and the third postnatal week. Functionally, prenatal hypoxia impaired resting ventilation and ventilatory response to hypoxia. The alterations of the catecholaminergic components of the chemoafferent pathway resulting from prenatal hypoxia might contribute to impair postnatal respiratory behaviour.

TRIZAL study: switching from successful HAART to Trizivir (abacavir-lamivudine-zidovudine combination tablet): 48 weeks efficacy, safety and adherence results.

OBJECTIVE: To assess the antiviral efficacy, safety, and adherence in subjects who switched to Trizivir following long-term HIV-1 RNA suppression. STUDY DESIGN: A randomized, open-label, multicentre, 48-week comparative study in subjects who have received two nucleoside reverse transcriptase inhibitors plus a protease inhibitor or an nonnucleoside reverse transcriptase inhibitor or three nucleoside reverse transcriptase inhibitors for at least 6 months, with a history of undetectable plasma HIV-1 RNA since initiation of therapy and plasma viral load of < 50 HIV-1 RNA copies/mL at screening. METHODS: Subjects were randomized 1:1 to continue their current treatment or to switch to a simplified treatment with Trizivir administered twice daily. Assessments included plasma HIV-1 RNA, lymphocyte counts, clinical laboratory evaluations, adverse events, and adherence to treatment (obtained via subject self-report). Treatment failure was defined as a plasma viral load of >/= 400 HIV-1 RNA copies/mL on two consecutive occasions or premature discontinuation of randomized treatment. RESULTS: At week 48, the proportion of treatment failures in Trizivir arm (23/106, 22%) was noninferior to that observed in continued arm (23/103, 22%) with a treatment difference stratified by prior ART of 1.2%[-10.1; 12.5]. Incidence of adverse events was similar in both treatment groups. The incidence of possible hypersensitivity reaction in the Trizivir trade mark arm was 10%. Significant reductions in cholesterol and triglyceride plasma levels were observed in the Trizivir arm (P < 0.001 and P = 0.006, respectively). CONCLUSION: Switching to Trizivir offers a potent and simplified regimen with equivalent efficacy and significant improvement in lipid abnormalities compared to continued triple therapy.

Neurochemical development of the brainstem catecholaminergic cell groups in rat.

The postnatal development of tyrosine hydroxylase activity has been studied in the brainstem catecholaminergic cell groups (A1C1, A2C2, A5, A6, A7), involved in cardiorespiratory control. In rat, at birth and at postnatal days P3, P7, P14, P21 ant P68, we used a microdissection technique followed by in vivo measurement of the tyrosine hydroxylase (TH) activity, the rate-limiting enzyme in catecholamine synthesis. There is two successive marked increases in TH activity: at P3 in every catecholaminergic cell groups (A1C1, +225%; A2C2, +300%; A5, +190%; A6, +205% compared to birth) and during the third postnatal week with a peak of TH activity at P14 (A6, +90% above the P7 level) or at P21 (A1C1, +715%; caudal A2C2, +585%; rostral A2C2, +15%; A5, +445%; A7, +180% compared to P7). The data suggest the existence of two temporal windows during the neurochemical development of the catecholaminergic cell groups, which correspond to two metabolic transitions. The first one could be related to the intra-, extrauterine transition and the second one, to a deep energetic phase of maturation in the rat brain, closely related to the maturation of cardiorespiratory processes.

Nonsteroid anti-inflammatory drugs inhibit both the activity and the inflammation-induced expression of acid-sensing ion channels in nociceptors.

Nonsteroid anti-inflammatory drugs (NSAIDs) are major drugs against inflammation and pain. They are well known inhibitors of cyclooxygenases (COXs). However, many studies indicate that they may also act on other targets. Acidosis is observed in inflammatory conditions such as chronic joint inflammation, in tumors and after ischemia, and greatly contributes to pain and hyperalgesia. Administration of NSAIDs reduces low-pH-induced pain. The acid sensitivity of nociceptors is associated with activation of H(+)-gated ion channels. Several of these, cloned recently, correspond to the acid-sensing ion channels (ASICs) and others to the vanilloid receptor family. This paper shows (1) that ASIC mRNAs are present in many small sensory neurons along with substance P and isolectin B4 and that, in case of inflammation, ASIC1a appears in some larger Abeta fibers, (2) that NSAIDs prevent the large increase of ASIC expression in sensory neurons induced by inflammation, and (3) that NSAIDs such as aspirin, diclofenac, and flurbiprofen directly inhibit ASIC currents on sensory neurons and when cloned ASICs are heterologously expressed. These results suggest that the combined capacity to block COXs and inhibit both inflammation-induced expression and activity of ASICs present in nociceptors is an important factor in the action of NSAIDs against pain.

Treatment intensification with abacavir in HIV-infected patients with at least 12 weeks previous lamivudine/zidovudine treatment.

OBJECTIVES: To demonstrate that lamivudine and zidovudine, given separately (lamivudine/zidovudine) or as a single combination tablet (Combivir), had equivalent efficacy. To evaluate the safety and antiretroviral activity of intensification with abacavir in patients treated with lamivudine/zidovudine for > or = 12 weeks. DESIGN: A 12-week, equivalence study of lamivudine/ zidovudine versus Combivir. Patients who completed this study could enter a 48-week, intensification study of Combivir plus abacavir. METHODS: In the equivalence study, treatment-naive patients were assessed for HIV-1 RNA, CD4 cell count and genotype. The same assessments plus phenotype were made in the intensification study. Serious adverse events were recorded in the equivalence study and all adverse events in the intensification study. RESULTS: Lamivudine/zidovudine (n=40) and Combivir (n=35) gave equivalent reductions in plasma HIV-1 RNA levels at week 12. An identical proportion of patients (74%) in each treatment group harboured virus with the M184V mutation after 12 weeks. Fifty-two patients entered the intensification study and 44 completed 48 weeks of treatment. At the time of intensification with abacavir, all 35 patients with evaluable isolates harboured HIV-1 containing M184V. Addition of abacavir to Combivir led to further decreases in plasma HIV-1 RNA and increases in CD4 cell counts compared with the start of intensification (P<0.001 at week 48). After 48 weeks of triple therapy, multi-nucleoside resistance mutations at codons 69 and 151 were not detected in any patients. All treatment regimens were generally well tolerated. CONCLUSION: Lamivudine/zidovudine and Combivir have equivalent antiretroviral activity over 12 weeks. Adding abacavir to Combivir can be a safe and effective therapeutic option for patients, including those harbouring virus with the M184V mutation.

Influence of cirrhosis on lamotrigine pharmacokinetics.

AIMS: Lamotrigine, an antiepileptic drug, is cleared from the systemic circulation mainly by glucuronidation. The possibility of changes in the pharmacokinetics of lamotrigine in plasma owing to hepatic dysfunction has been evaluated. METHODS: Thirty-six subjects, including 24 patients with various degrees of liver cirrhosis and 12 healthy volunteers received a single 100 mg dose of lamotrgine. Blood samples were taken for 7 days in all subjects, except nine with severe cirrhosis, who had a 29 day blood sampling period. RESULTS: The pharmacokinetics of lamotrigine were comparable between the patients with moderate cirrhosis (corresponding to Child-Pugh grade A) and the healthy subjects. Plasma oral clearance mean ratios (90% confidence interval) in patients with severe cirrhosis without or with ascites (corresponding, respectively, to Child-Pugh grade B and C) to healthy subjects were, respectively, 60% (44%, 83%) and 36% (25%, 52%). Plasma half-life mean ratios (90% confidence interval) in these two patient groups to healthy subjects were, respectively, 204% (149%, 278%) and 287% (202%, 408%). CONCLUSIONS: Lamotrigine administered as a single oral dose of 100 mg was well tolerated in all groups. Initial, escalation and maintenance doses should generally be reduced by approximately 50 or 75% in patients with Child-Pugh Grade B or C cirrhosis. Escalation and maintenance doses should be adjusted according to clinical response.

Effects of gestational hypoxia on mRNA levels of Glut3 and Glut4 transporters, hypoxia inducible factor-1 and thyroid hormone receptors in developing rat brain.

Alterations of brain development result from noxious intrauterine signals, as oxygen deprivation, which decrease glucose energetic yield. To verify the hypothesis that a defect of brain energetic adaptation is responsible for these alterations, we have studied the effects of gestational hypoxia (10% oxygen during the last 2 weeks of fetal life) on cerebral ontogenesis of glucose transporters which control the limiting step of glucose utilization by neurons. This study is realised in rats by quantification of whole brain Glut3 and Glut4 mRNA in 14- and 19-day-old embryos (E14, E19), newborn (P0) and 7 postnatal-day-old rats (P7) by using reverse transcription-polymerase chain reaction (RT-PCR) method. We have associated our study with the analysis of a transcriptional factor, the hypoxia inducible factor-1alpha (HIF-1alpha), known to control the expression of glucose transporter, and with a family of transcriptional factors, the thyroid hormone receptors (TR), regulating specific genes involved in brain development. The data show (1) for the first time the Glut4 and HIF-1alpha gene expression in fetal rat brain which are detected as soon as E14, (2) that gestational hypoxia induces an increase of mRNA transcript levels of Glut3, Glut4, TRalpha2, TRbeta1 and HIF-1alpha genes mainly or exclusively at E14, and (3) that the absence of response of Glut3 and HIF-1alpha at E19 in hypoxic vs. normoxic group could indicate an insufficient energetic adaptation at this period of development which could lead to the neural alterations observed postnatally.

Lack of a pharmacokinetic interaction between atovaquone and proguanil.

OBJECTIVE: To assess the magnitude of the putative effect of atovaquone on the pharmacokinetics of proguanil and to determine whether the pharmacokinetics of atovaquone are affected by concomitant administration of proguanil, with both drugs administered for 3 days to healthy adult volunteers. METHODS: This was an open-label, randomized, three-way cross-over study, in which 18 healthy volunteers received 400 mg proguanil, 1000 mg atovaquone and 1000 mg atovaquone + 400 mg proguanil. Each treatment was given once daily for 3 days with a 3-week wash-out period between each occasion. For the assay of proguanil, cycloguanil and atovaquone, blood was sampled before dosing and at regular intervals over 8 days when proguanil was given, and over 17 days when atovaquone was given. RESULTS: The geometric mean of the area under the atovaquone plasma concentration-time curve calculated from 0 to 24 h after the last dose (AUC0->24h) was 180 microg x ml(-1) h following administration of atovaquone alone and 193 microg x ml(-1) h following atovaquone with proguanil. The geometric mean AUC0->24h for proguanil was 6296 ng x ml(-1) x h after proguanil alone and 5819 ng x ml(-1) x h following proguanil with atovaquone. The corresponding values for the metabolite cycloguanil were 1297 ng x ml(-1) x h and 1187 ng x ml(-1) x h, respectively. The geometric mean elimination half-life (t1/2) of atovaquone was 57.1 h when given alone and 59.0 h when administered together with proguanil. The corresponding geometric mean values of t1/2 for proguanil were 13.7 h and 14.5 h. Exploratory statistical analysis showed no important gender effects on the pharmacokinetics of atovaquone, proguanil, or cycloguanil. CONCLUSION: The pharmacokinetics of atovaquone and proguanil and its metabolite, cycloguanil, were not different when atovaquone and proguanil were given alone or in combination.

Effects of tablet and effervescent formulations of ranitidine 75 mg and cimetidine 200 mg on gastric acidity and oesophageal acid exposure in healthy humans.

BACKGROUND: Because of their tolerance and safety, low doses of H2-receptor antagonists are now increasingly used in some countries for self-care medication of gastro-oesophageal reflux symptoms. AIM: The purpose of this randomized, double-blind, placebo-controlled, five-way crossover study was to determine and to compare the effects of low doses of ranitidine and cimetidine both on gastric pH and on oesophageal acid exposure. METHODS: Gastric and oesophageal pH were simultaneously monitored in 20 healthy subjects using two glass pH electrodes, after placebo and single doses of ranitidine 75 mg and cimetidine 200 mg (effervescent and tablet forms), for 4 h before and after a meal. RESULTS: During the fasting period, median gastric pH rose significantly with both drugs, but more rapidly with the effervescent forms; the oesophageal acid exposure was significantly decreased by all drug regimens. After the meal, although there was no significant difference in gastric pH values, oesophageal acid exposure was significantly decreased in comparison with placebo with both forms of ranitidine (P < 0.05), and also for ranitidine tablets in comparison with cimetidine tablets (P < 0.05). CONCLUSIONS: Low doses of ranitidine and cimetidine increase gastric pH, with a more pronounced effect for ranitidine. Effervescent formulations of both drugs induce a slightly more rapid initial increase in pH than tablets. Ranitidine demonstrates a more prolonged effect than cimetidine and decreases oesophageal acid exposure monitored after a meal ingested 4 h after the drug intake.

Comparative clinical pharmacokinetics of single doses of sumatriptan following subcutaneous, oral, rectal and intranasal administration.

Sumatriptan, a 5-HT1 receptor agonist active for the acute treatment of migraine, is currently available as subcutaneous injection and oral tablets. Rectal or intranasal formulations may offer advantages over those marketed. This study compared the pharmacokinetics of sumatriptan via all four routes. Usual absorption parameters were described and the rate of absorption was assessed using deconvolution technics. There were no statistical differences between the non-parenteral routes for tmax or Cmax/AUCinfinity. However, Cmax and AUCtmax were statistically greater with the suppository than with the tablet, but there was no difference between intranasal and oral routes. The highest rate of absorption occurred earlier with the intranasal than with the oral route. Relative to the subcutaneous route, the bioavailability for the suppository was greater than for intranasal spray and oral tablet. The amount of sumatriptan excreted in the urine unchanged was similar for all routes. Sumatriptan in this study was well tolerated.

Effect of alosetron on responses to colonic distension in patients with irritable bowel syndrome.

BACKGROUND: Visceral hypersensitivity plays a major role in the pathophysiology of irritable bowel syndrome, as shown by balloon distension studies. 5-HT3 receptors on afferent nerves may modulate visceral sensitivity and be the target of new treatments for irritable bowel syndrome. AIM: To evaluate the effects of alosetron, a potent and selective 5-HT3 antagonist, on the perception of colonic distension by patients with irritable bowel syndrome, and on the colonic compliance to distension with a barostat. METHODS: Twenty-five irritable bowel syndrome patients were included in a randomized double-blind parallel group trial; data were available for 22 (Rome criteria; 48 +/- 11 years: 13 men and nine women). Patients were treated for 7 days with placebo (n = 6), alosetron 0.25 mg b.d. (n = 8) or alosetron 4 mg b.d. (n = 8). On day 6, a barostat bag was placed in the left colon. On day 7, after an overnight fast, isobaric phasic distensions were performed (4 mmHg steps, 5 min) up to the step triggering a sensation of abdominal pain. RESULTS: Groups were comparable at inclusion (age, sex, symptoms, bowel habits). There were no differences between treatment groups in pressure recorded within the bag at the time of first sensation of abdominal pain. However, bag volumes were significantly increased. At the first sensation threshold, median volume differences of 61 mL and 90 mL (P = 0.028) were recorded with alosetron 0.25 mg b.d. and 4 mg b.d., respectively. At the threshold of abdominal pain, these differences were 71 mL (P = 0.039) and 84 mL (P = 0.017). Colonic compliance increased from 5.9 mL/mmHg on placebo to 7.6 mL/mmHg on alosetron 0.25 mg b.d. and to 9.8 mL/mmHg (P = 0.034) on alosetron 4 mg b.d. CONCLUSION: Alosetron increases the compliance of the colon to distension, and could thereby contribute to changes in perception of colonic distension and improvement in the symptoms of irritable bowel syndrome.

Ondansetron compared with metoclopramide in the treatment of established postoperative nausea and vomiting. The French Ondansetron Study Group.

We have studied 746 males and females undergoing general anaesthesia for any type of surgical procedure in a double-blind, controlled, randomized study. After experiencing at least one nausea and/or one emetic episode in the 6 h after recovery from anaesthesia, patients received either ondansetron 4 mg i.v. or metoclopramide 10 mg i.v. Patients were observed for postoperative nausea and vomiting (PONV) for 24 h after drug administration. Complete control of PONV was achieved more frequently in the ondansetron-treated patients compared with the metoclopramide-treated patients during the 24-h period (59% vs 41% (P < 0.001) and 44% vs 34% (P = 0.006) for emetic episodes and nausea, respectively). Furthermore, ondansetron was associated with greater patient satisfaction than metoclopramide (P < 0.001) with 49% and 32% of patients, respectively, very satisfied. The overall incidence of adverse events was similar in the ondansetron (7%) and metoclopramide (8%) groups. Ondansetron was as well tolerated and more effective than metoclopramide for all assessment criteria in the treatment of established PONV.

No need to adjust the dose of 311C90 (zolmitriptan), a novel anti-migraine treatment, in patients with renal failure not requiring dialysis.

311C90 ("Zomig", zolmitriptan), is a novel and selective, centrally and peripherally acting 5 HT1B/1D receptor agonist in development for the acute, oral treatment of migraine. We have conducted a parallel group study in patients with moderate/severe renal impairment (creatinine clearance < or = 40 ml/min) and age- and sex-matched healthy volunteers (creatinine clearance > or = 60 ml/min). All subjects received a single, 10 mg dose of 311C90. Mean peak concentrations of 311C90 and its pharmacologically active N-desmethyl metabolite (183C91) were similar in both groups although AUC0-infinity for 183C91 was increased by 35% in the renally impaired patients. Other pharmacokinetic parameters were little changed apart from the expected reduction in CLR and urinary recovery and a small increase of 0.9 and 1.0 h, respectively, in the mean half-lives of 311C90 and 183C91. For the 2 inactive metabolites, the N-oxide (1652W92) and the indolacetic acid (2161W92), mean peak concentrations were approximately 3 times higher in renally impaired patients than in healthy volunteers and AUC0-infinity was 6-7.5 times higher. CLR for these metabolites was approximately 90% lower in renal impairment and half-life of both was increased approximately 3-fold. Baseline blood pressures were higher in the renally impaired group. After 311C90 there was a transient, small increase in blood pressure in both groups. There was little difference in the increase in diastolic blood pressure between the groups (16 mmHg in both) but the rise in systolic blood pressure was greater in the renally impaired group (23 mmHg vs 16 mmHg in healthy subjects). The lack of substantial changes in the plasma concentrations of both parent compound and 183C91, and the similarity of the changes in blood pressure, in renally impaired subjects compared to healthy volunteers suggest that there is no reason to adjust the dose of 311C90 in patients with renal impairment.

Prognostic value of clinicopathological parameters in head and neck squamous cell carcinoma: a prospective analysis.

The prognostic weight of histological and biological factors was compared with that of known clinical prognostic factors in a population of 108 consecutive previously untreated patients with head and neck squamous cell carcinoma. Parameters studied were: tumour vascularisation, mitotic index, histological differentiation, nuclear grade, keratinisation, desmoplasia, growth pattern, inflammation, tumour emboli in peripheral vessels, keratins 6, 13, 19 immunohistochemical expression, cytofluorometric ploidy and S-phase. In multivariate analysis (Cox), only age and nodal status had a significant impact on the overall survival, whereas T stage was the only significant factor associated with locoregional failure. The cumulative incidence of metastases was correlated not only with age, T and N stage, but also with histological differentiation. All the other histological and biological factors studied failed to provide further prognostic information. These findings may help to select patients with high metastatic risk.