Control of SHIV-89.6P-infection of cynomolgus monkeys by HIV-1 Tat protein vaccine.

Vaccine strategies aimed at blocking virus entry have so far failed to induce protection against heterologous viruses. Thus, the control of viral infection and the block of disease onset may represent a more achievable goal of human immunodeficiency virus (HIV) vaccine strategies. Here we show that vaccination of cynomolgus monkeys with a biologically active HIV-1 Tat protein is safe, elicits a broad (humoral and cellular) specific immune response and reduces infection with the highly pathogenic simian-human immunodeficiency virus (SHIV)-89.6P to undetectable levels, preventing the CD4+ T-cell decrease. These results may provide new opportunities for the development of a vaccine against AIDS.

Reproductive phenology of Melastomataceae species with contrasting reproductive systems: contemporary and historical drivers.

Flowering and fruiting are key events in the life history of plants, and both are critical to their reproductive success. Besides the role of evolutionary history, plant reproductive phenology is regulated by abiotic factors and shaped by biotic interactions with pollinators and seed dispersers. In Melastomataceae, a dominant Neotropical family, the reproductive systems vary from allogamous with biotic pollination to apomictic, and seed dispersal varies from dry (self-dispersed) to fleshy (animal-dispersed) fruits. Such variety in reproductive strategies is likely to affect flowering and fruiting phenologies. In this study, we described the reproductive phenology of 81 Melastomataceae species occurring in two biodiversity hotspots: the Atlantic rain forest and the campo rupestre. We aim to disentangle the role of abiotic and biotic factors defining flowering and fruiting times of Melastomataceae species, considering the contrasting breeding and seed dispersal systems, and their evolutionary history. In both vegetation types, pollinator-dependent species had higher flowering seasonality than pollinator-independent ones. Flowering patterns presented phylogenetic signal regardless of vegetation type. Fruiting of fleshy-fruited species was seasonal in campo rupestre but not in Atlantic rain forest; the fruiting of dry-fruited species was also not seasonal in both vegetation types. Fruiting showed a low phylogenetic signal, probably because the influence of environment and dispersal agents on fruiting time is stronger than the phylogenetic affinity. Considering these ecophylogenetic patterns, our results indicate that flowering may be shaped by the different reproductive strategies of Melastomataceae lineages, while fruiting patterns may be governed mainly by the seed dispersal strategy and flowering time, with less phylogenetic influence.

High-performance liquid chromatography measurement of hyperforin and its reduced derivatives in rodent plasma.

A reverse-phase high-performance liquid chromatography method was developed for the determination of hyperforin and its reduced derivatives octahydrohyperforin and tetrahydrohyperforin in rodent plasma. The procedure includes solid-phase extraction from plasma using the Baker 3cc C8 cartridge, resolution on the Symmetry Shield RP8 column (150 mm x 4.6 mm, i.d. 3.5 microm) and UV absorbance detection at 300 nm. The assay was linear over a wide range, with an overall coefficient of variation less than 10% for all compounds. The precision and accuracy were within acceptable limits and the limit of quantitation was sufficient for studies preliminarily assessing the disposition of tetrahydrohyperforin and octahydrohyperforin in the mouse and rat.

Immune activation in africa is environmentally-driven and is associated with upregulation of CCR5. Italian-Ugandan AIDS Project.

BACKGROUND: HIV infection in Africa is associated with immune activation and a cytokine profile that stimulates CCR5 expression. We investigated whether this immune activation is environmentally driven; if a dominant expression of CCR5 could indeed be detected in African individuals; and if R5 HIV strains would be prevalent in this population. METHODS: Freshly drawn peripheral blood mononuclear cells from HIV-uninfected African and Italian individuals living in rural Africa, from HIV-uninfected Africans and Italians living in Italy, and from HIV-infected African and Italian patients were analysed. Determinations of HIV coreceptor-specific mRNAs and immunophenotype analyses were performed in all samples. Virological analyses included virus isolation and characterization of plasma neutralizing activity. FINDINGS: Results showed that: immune activation is detected both in Italian and African HIV-uninfected individuals living in Africa but not in African subjects living in Italy; CCR5-specific mRNA is augmented and the surface expression of CCR5 is increased in African compared with Italian residents (CXCR4-specific mRNA is comparable); R5-HIV strains are isolated prevalently from lymphocytes of African HIV-infected patients; and plasma neutralizing activity in HIV-infected African patients is mostly specific for R5 strains. CONCLUSIONS: Immune activation in African residents is environmentally driven and not genetically predetermined. This immune activation results in a skewing of the CCR5 : CXCR4 ratio which is associated with a prevalent isolation of R5 viruses. These data suggest that the selection of the predominant virus strain within the population could be influenced by an immunologically driven pattern of HIV co receptor expression.

Conservation of a putative AP1 binding site and complete homology to a fetal brain EST in a region upstream of the core muscle promoter in the human dystrophin gene.

A region of 744 basepairs (bp) upstream of the muscular dystrophin promoter (UMDP) was amplified by inverse-polymerase chain reaction (PCR), cloned and sequenced. Analysis of this sequence for the presence of putative transcriptional control elements identified several similarities with known cis-acting sequence motifs including two MyoD and two Ap1 motifs. One of these Ap1 motifs was found to be completely conserved within an otherwise highly variable region among five primate species. Complete homology to a human fetal brain expressed sequence tag (EST) was also observed over 201 bp at the 5' end of the UMDP region. Northern blot analysis using a radiolabelled EST probe identified a 1 kb mRNA expressed in human placenta and at lower levels in the heart. These results raise the possibility that additional transcriptional regulatory elements are located upstream of the core muscle promoter, and provide the first evidence for the existence of a gene that overlaps the human dystrophin gene.

Effects of short- and long-term administration of fluoxetine on the monoamine content of rat brain.

The effects of repeated doses of fluoxetine over time and dose-responses of the content of indoles and catecholamines and metabolism, were examined in rats in relation to the concentrations of the parent compound and its active metabolite norfluoxetine in brain. Brains were removed for assays of the regional content of monoamines and concentrations of drugs 24 hr after the last dose on days 1, 7 and 21 of a twice-daily schedule of fluoxetine (15 mg/kg, i.p.). Measurements were also taken 1 week after the last dose (7.5 and 15 mg/kg, b.i.d.) of the 21-day regimen. On day 1 fluoxetine did not change the content of serotonin (5-HT) but reduced the concentrations of 5-hydroxyindolacetic acid (5-HIAA) in the hippocampus and cortex, compatible with the action of a blocker of the uptake of 5-HT. Continued injections of fluoxetine, however, significantly reduced 5-HT in the brain of the rat, the depletion being significant on days 7 and 21 in the hippocampus and cortex, respectively. The content of indoles remained significantly decreased for at least a week after the last dose of fluoxetine in the 21-day regimen, although the concentrations of 5-HIAA (but not 5-HT) totally recovered at the smaller dose (7.5 mg/kg) in all regions of the brain (cortex, hippocampus and striatum). In spite of slight changes in the concentrations and metabolism of dopamine (DA) in the striatum, 24 hr after the last dose (15 mg/kg), treatment with drug had no significant long-term effects on the content of catecholamines in these regions of the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intracerebroventricular administration of d-fenfluramine and d-norfenfluramine, as a single injection or 2-hr infusion, on serotonin in brain: relationship to concentrations of drugs in brain.

The effects of d-fenfluramine (DF) and d-norfenfluramine (DNF), administered intracerebroventricularly (i.c.v.) on levels of serotonin (5-HT) in the brain, was assessed in relation to levels of drugs in brain. d-Fenfluramine, as a single injection (500 micrograms/20 microliters), caused no significant changes in 5-HT in whole brain from 15 to 480 min after injection. When infused intraventricularly for 2 hr, DF and DNF at 500 but not at 125 250 micrograms/hr, markedly reduced concentrations of 5-HT in brain 4 hr after the end of the infusion. At this time levels of DNF in brain were similar (between 4 and 5 micrograms/g) with both compounds, whereas levels of DNF after single intraventricular injections of DF were below 2 micrograms/g at all times after injection. Infusion of 500 micrograms/hr of DNF for 2-hr reduced concentrations of 5-HT in various regions of the brain, with the exception of the brainstem, whereas 250 micrograms/hr of DNF significantly lowered levels of 5-HT only in the cortex. The effect of infusion of 500 micrograms/hr of DNF was specific for 5-HT (no effect on dopamine and norepinephrine) and lasted for at least 168 hr. The results suggest that the effect on 5-HT in brain of intraventricular infusion of DF, but not a single injection, was due to the fact that, only in the former condition were adequate levels of DNF, the active metabolite of DF, reached in the brain. These results are relevant to the interpretation of studies in which biochemical changes in the brain after intraventricular administration, are reported without any measurement of the drug or its active metabolites, in plasma and brain.

Depletion and time-course of recovery of brain serotonin after repeated subcutaneous dexfenfluramine in the mouse. A comparison with the rat.

The indole-depleting effects of repeated subcutaneous doses of dexfenfluramine (D-F) (2.5, 5, 10, 20 and 40 mg/kg/day, for four days) in mice were examined with regard to the initial response and time-course of recovery and related to the pharmacokinetics of D-F and its active metabolite dexnorfenfluramine (D-NF). Steady-state plasma and brain concentrations of D-F rose dose-dependently with a metabolite-to-drug ratio averaging 0.4 in brain. This confirmed that in mice D-NF contributes less than in other species to the effects of D-F. Regional serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents were decreased dose-dependently 4 hr after the last injection of D-F. However, two weeks after D-F (2.5-10 mg/kg/day) brain indoles had almost totally recovered, and the long-term effects of the 20 mg/kg/day dose were completely reversed by six weeks, when significant effects are still observable in rats. Although substantial recovery was evident even at 40 mg/kg/day, 5-HT but not 5-HIAA was still slightly reduced nine weeks later. Comparative studies in rats given 2.5-20 mg/kg/day D-F indicated much more severe initial indole depletions than in mice. Brain levels of D-F and D-NF were much higher in rats than in mice. The total active drug brain concentration (D-F + D-NF) was significantly correlated with 5-HT content in both species, with approx 20 nmol/g of total drug causing 50% reduction. These findings point to species differences in D-F kinetics as a main reason for differences in the neurochemical response, supporting the view that the recovery of indoles over time is related to the extent of initial depletion, which in turn depends on critical drug brain concentrations. In view of the qualitative and quantitative species differences in the pharmacodynamics and pharmacokinetics of D-F neither of these rodent species is a suitable model for predicting potential drug toxicity in humans.

Novel and highly potent 5-HT3 receptor agonists based on a pyrroloquinoxaline structure.

The synthesis and the biological evaluation of a series of novel pyrroloquinoxaline derivatives are described. In binding studies several compounds proved to be potent and selective 5-HT3 receptor ligands. The most active pyrroloquinoxalines, 11d and 11e, showed a subnanomolar affinity for 5-HT3 receptor and were able to functionally discriminate the central and peripheral 5-HT3 receptor, being agonists and antagonists, respectively. In functional studies ([14C]-guanidinium accumulation test in NG 108-15 cells, in vitro) most of the synthesized compounds showed clear-cut 5-HT3 agonist properties. In in vivo studies on the von Bezold-Jarisch reflex test (a peripheral interaction model) the behavior of the tested compounds ranged from agonist to antagonist, while clear agonist properties were obtained with 12a on cortical acetylcholine release in freely moving rats. Pharmacokinetic studies with 11e and 12c indicate that the compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio of 17.5 and 37.5, respectively. Thus compounds 11e and 12c represent the most potent central 5-HT3 agonists identified to date that are able to cross the blood-brain barrier.

Pyrroloquinoxaline derivatives as high-affinity and selective 5-HT(3) receptor agonists: synthesis, further structure-activity relationships, and biological studies.

The synthesis, pharmacological evaluation, and structure-activity relationships (SARs) of a series of novel pyrroloquinoxalines and heteroaromatic-related derivatives are described. The new pyrroloquinoxaline-related ligands were tested in rat cortex, a tissue expressing high density of 5-HT(3) receptors, and on NG108-15 cells and exhibited IC(50) values in the low nanomolar or subnanomolar range, as measured by the inhibition of [(3)H]zacopride binding. The SAR studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1, L2, and L3 in the 5-HT(3) receptor cleft, while the 7-OH pyrroloquinoxaline analogue was designed to investigate hydrogen bonding with a putative receptor site H1 possibly interacting with the serotonin hydroxy group. The most active pyrroloquinoxaline derivatives showed subnanomolar affinity for the 5-HT(3) receptor. In functional studies ([(14)C]guanidinium accumulation test in NG108-15 hybrid cells, in vitro) most of the tested compounds showed clear-cut 5-HT(3) agonist properties, while some others were found to be partial agonists. Several heteroaromatic systems, bearing N-substituted piperazine moieties, have been explored with respect to 5-HT(3) affinity, and novel structural leads for the development of potent and selective central 5-HT(3) receptor agonists have been identified. Preliminary pharmacokinetic studies indicate that these compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio between 2 and 20, unless they bear a highly hydrophilic group on the piperazine ring. None of the tested compounds showed in vivo anxiolytic-like activity, but potential analgesic-like properties have been possibly disclosed for this new class of 5-HT(3) receptor agonists.

The effects of single and repeated anorectic doses of 5-hydroxytryptamine uptake inhibitors on indole levels in rat brain.

1. The effects of acute and repeated equiactive anorectic doses (ED50) of recently marketed 5-hydroxytryptamine (5-HT) uptake inhibitors on the content of brain indoles were compared in rats in relation to the brain regional concentrations of unchanged drug and its known active metabolite. 2. Single intraperitoneal (i.p.) doses of the anorectic ED50 of fluoxetine (35 mumol kg-1), fluvoxamine (60 mumol kg-1), paroxetine (20 mumol kg-1) and sertraline (49 mumol kg-1) slightly reduced brain 5-hydroxyindoleacetic acid (5-HIAA), with regional differences, this being compatible with 5-HT uptake blockade. Only fluvoxamine and sertraline significantly enhanced the content of 5-HT in the cortex. 3. The regional sensitivity to the acute effect of a given drug was not related to any preferential drug distribution, as these compounds distributed almost uniformly in the brain areas considered (cortex, striatum and hippocampus). 4. Repeating the same doses twice daily, i.p. for 14 days, however gave a different picture, fluvoxamine having little or no effect on the content of indoles and fluoxetine, paroxetine and sertraline lowering both 5-HT and 5-HIAA in all the brain regions compared to pair-fed control animals, 1 h after the last dose. 5. One week later only fluoxetine-treated animals still had reduced brain 5-HT, this probably being related to the accumulation of its main metabolite norfluoxetine in rat brain after chronic dosing. 6. Further studies on the relationship between the long-term neurochemical changes and anorectic activity are required but it appears from these results that anorectic drugs with similar acute effects on 5-HT uptake may differ in their long-term effects on 5-HT mechanisms.

Brain-to-blood partition and in vivo inhibition of 5-hydroxytryptamine reuptake and quipazine-mediated behaviour of nefazodone and its main active metabolites in rodents.

The brain/plasma partition of nefazodone, hydroxynefazodone (OHNFZ) and m-chlorophenyl-piperazine (mCPP) and their antagonism of p-chloroamphetamine (PCA)-induced 5-hydroxytryptamine (5-HT) depletion and quipazine-induced head twitches were compared in rodents. Nefazodone (30 mg kg(-1), i.p.) rapidly entered the brain but concentrations were exceeded by mCPP, the metabolic ratio being 47 and 10 in the mouse and rat respectively. OHNFZ was detectable in plasma but never in brain. Brain concentrations of OHNFZ in the mouse (30 mg kg(-1), i.p.) were less than 10% of those in plasma, confirming a poor blood-brain barrier penetration. Concentrations of its metabolite mCPP were similar to those after 5 mg kg(-1)(i.p.) mCPP. In the mouse, nefazodone (30 mg kg(-1)) antagonized the 5-HT depleting effect of PCA 2 h after dosing, when it had disappeared from brain but when mCPP concentrations were similar to those after 5 mg kg(-1) (i.p.) mCPP. However, mCPP antagonized PCA less than nefazodone. In the rat, nefazodone pretreatment (30 mg kg(-1), 15 min) prevented (97% of inhibition) quipazine-induced head twitches. The effect was weaker (65% of inhibition) but significant when only mCPP was detected in brain. Analysis of brain concentrations of the two compounds after their ED50 against quipazine indicated that both contributed to the effect, although nefazodone was more active than mCPP in terms of concentrations required to obtain a comparable reduction of twitches. These findings show that mCPP concentrates in the brain following injection of nefazodone and may play a role in preventing quipazine-induced behaviour and PCA-induced 5-HT depletion. In contrast OHNFZ poorly enters the brain and its in vivo activity is mostly due to its biotransformation to mCPP.

Citalopram-induced hypophagia is enhanced by blockade of 5-HT(1A) receptors: role of 5-HT(2C) receptors.

The selective 5-hydroxytryptamine reuptake inhibitor citalopram (10 and 20 mg kg(-1), i.p.) significantly reduced food intake in male rats (CD-COBS) habituated to eat their daily food during a 4-h period. The 5-HT1A receptor antagonist WAY100635 (0.3 mg kg(-1)) administered systemically did not modify feeding but significantly potentiated the reduction in food intake caused by 10 mg kg(-1) i.p. citalopram. The dose of 5 mg kg(-1) i.p. citalopram was not active in animals pretreated with vehicle but significantly reduced feeding in animals pretreated with WAY100635. WAY100635 (0.1 microg 0.5 microl(-1)) injected into the dorsal raphe significantly potentiated the hypophagic effect of 10 mg kg(-1) citalopram. WAY100635 (1.0 microg 0.5 microl(-1)) injected into the median raphe did not modify feeding or the hypophagic effect of 10 mg kg(-1) citalopram. The 5-HT2B/2C receptor antagonist SB206553 (10 mg kg(-1), p.o.) slightly reduced feeding by itself but partially antagonized the effect of WAY100635 administered systemically (0.3 mg kg(-1), s.c.) or into the dorsal raphe (0.1 microg 0.5 microl(-1)) in combination with 10 mg kg(-1) i.p. citalopram. The hypophagic effect of 10 mg kg(-1) i.p. citalopram alone was not significantly modified by SB206553. Brain concentrations of citalopram and its metabolite desmethylcitalopram in rats pretreated with SB206553, WAY100635 and their combination were comparable to those of vehicle-pretreated rats, 90 min after citalopram injection. The hypophagic effect of citalopram was potentiated by blocking 5-HT1A receptors. Only the effect of the WAY100635/citalopram combination seemed to be partially mediated by central 5-HT2C receptors.

Effects of chronic treatment with escitalopram or citalopram on extracellular 5-HT in the prefrontal cortex of rats: role of 5-HT1A receptors.

1 Microdialysis was used to study the acute and chronic effects of escitalopram (S-citalopram; ESCIT) and chronic citalopram (CIT), together with the 5-HT1A receptor antagonist WAY100,635 (N-[2-[methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexane carboxamide trihydrochloride) and the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), on extracellular 5-hydroxytryptamine (5-HT) levels in the rat prefrontal cortex. 2 Extracellular 5-HT rose to 234 and 298% of basal values after subcutaneous (s.c.) acute doses of 0.15 and 0.63 mg kg(-1) ESCIT. No further increase was observed at 2.5 mg kg(-1) ESCIT (290%). 3 The effect of 13-day s.c. infusion of 10 mg kg(-1) day(-1) ESCIT on extracellular 5-HT (422% of baseline) was greater than after 2 days (257% of baseline), whereas exposure to ESCIT was similar. In contrast, the increase in extracellular 5-HT induced by the infusion of CIT for 2 (306%) and 13 days (302%) was similar. However, brain and plasma levels of S-citalopram in rats infused with CIT for 13 days were lower than after 2 days. 4 Acute treatment with 2.5 mg kg(-1) ESCIT or 5 mg kg(-1) CIT raised extracellular 5-HT by 243 and 276%, respectively, in rats given chronic vehicle but had no effect in rats given ESCIT (10 mg kg(-1) day(-1)) or CIT (20 mg kg(-1) day(-1)) for 2 or 13 days, suggesting that the infused doses had maximally increased extracellular 5-HT. WAY100,635 (0.1 mg kg(-1) s.c.) increased extracellular 5-HT levels by 168, 174 and 169% of prechallenge values in rats infused with vehicle or ESCIT for 2 or 13 days, respectively. WAY100,635 enhanced extracellular 5-HT levels to 226, 153 and 164% of prechallenge values in rats infused with vehicle or CIT for 2 and 13 days, respectively. 5 8-OH-DPAT (0.025 mg kg(-1)) reduced extracellular 5-HT by 54% in control rats, but had no effect in those given ESCIT and CIT for 13 days. 6 This series of experiments led to the conclusion that chronic treatment with ESCIT desensitizes the 5-HT1A receptors, regulating the release of 5-HT in the prefrontal cortex and enhances the effect of the drug on extracellular 5-HT. They also indicate that chronic treatment with ESCIT and CIT did not prevent WAY100,635 from raising extracellular 5-HT.

Reciprocal interaction of 5-hydroxytryptamine and cholecystokinin in the control of feeding patterns in rats.

1. The effect of the CCKA receptor antagonist, devazepide (100 mg kg-1) on meal parameters during the initial phase of the dark period was studied in free-feeding rats by use of a procedure for continuously monitoring feeding patterns. 2. In a second experiment, the effect of devazepide on the reduction in meal parameters induced by the 5-hydroxytryptamine (5-HT) releaser and uptake inhibitor, (+)-fenfluramine (1.5 mg kg-1) in 4 h food-deprived rats was examined. 3. The hypophagic effect of an intraperitoneal injection of cholecystokinin (CCK-8, 4 micrograms kg-1) was studied in rats treated with the 5-HT receptor antagonist, metergoline (1 and 2 mg kg-1). 4. Devazepide increased the size of the first meal in free-feeding, but not in 4 h food-deprived rats and partially antagonized the effect of (+)-fenfluramine on the size and duration of the first meal. The reduction in eating rate induced by (+)-fenfluramine was not modified by devazepide. No changes in (+)-fenfluramine or (+)-norfenfluramine levels were found in the brain of rats treated with devazepide. 5. The effect of CCK-8 on meal size was completely antagonized by 2 mg kg-1 metergoline. A significant interaction was also found between 2 mg kg-1 metergoline and CCK-8 as regards their effect on the inter-meal interval. 6. The results suggest a reciprocal interaction between 5-HT and CCK-8 in enhancing the satiating effect of food in rats.

Chronic treatment with reboxetine by osmotic pumps facilitates its effect on extracellular noradrenaline and may desensitize alpha(2)-adrenoceptors in the prefrontal cortex.

1. This study investigated the effect of acute (2 days) and chronic (14 days) treatment with a selective inhibitor of noradrenaline uptake, reboxetine (10 mg kg(-1) day(-1)) by osmotic pumps, on extracellular noradrenaline and the sensitivity of alpha(2)-adrenoceptors in the prefrontal cortex of rats. 2. The effect of continuous infusion of reboxetine for 14 days on cortical extracellular noradrenaline was significantly higher (599% of vehicle levels) than after 2 days (263% of vehicle levels). 3. Brain concentrations of reboxetine after 2 and 14 days of infusion were 37.9+/-17.8 and 37.1+/-7.7 ng g(-1), respectively. 4. Reboxetine infused for 2 and 14 days significantly increased extracellular dopamine in the prefrontal cortex, to a similar extent (257 and 342% of vehicle levels, respectively), whereas extracellular 5-HT was not modified by either treatment. 5. Clonidine (10 and 30 microg kg(-1) i.p.) reduced cortical extracellular noradrenaline similarly in animals treated with reboxetine or vehicle for 2 days whereas the effects in rats infused with reboxetine for 14 days were markedly less than in vehicle-treated animals. 6. Clonidine (0.05 and 0.2 microM), infused through the dialysis probe into the prefrontal cortex, reduced cortical extracellular noradrenaline much less in rats treated with reboxetine for 14 days than in vehicle-treated animals. 7. Reboxetine's effect on extracellular noradrenaline in the prefrontal cortex was greater after chronic treatment and could be associated with desensitization of terminal alpha(2)-adrenoceptors that normally serve to inhibit noradrenaline release.

The role of HIV type 1 phenotype and genotype in long-term responders to zidovudine therapy.

We performed a cross-sectional and partly retrospective virological evaluation of 31 long-term responders (LTRs) to zidovudine (ZDV) (persistent increase in the CD4+ cell counts without progression of HIV infection throughout a period of ZDV therapy > 3 years) and 17 well-matched controls who developed a marked immunological deterioration over a 24-month period of ZDV therapy. The biological phenotype of HIV-1 was assessed by testing the capacity of the isolates to replicate in the MT-2, HUT-78, C-8166, and U-937 T cell lines, and mutations at codons 215 and 41 of RT were checked in proviral DNA from uncultured PBMCs. Show/low non-syncytium-inducing (S/L-NSI) and rapid/high syncytium-inducing (R/H-SI) variants were detected in 25 (81%) and 2 (6%) LTRs, respectively. HIV-1 could not be isolated in the remaining four LTRs (13%). Conversely, 12 of 17 (71%) controls yielded R/H-SI variants. Conversion from the S/L-NSI to R/H to R/H-SI phenotype occurred in 5 controls but in none of the 18 LTRs tested. Mutant sequences in proviral DNA from control PBMCs were consistently detected (94%), while a wild-type sequence of the residues investigated was found in the majority of LTRs (77%). In our series, patients who received immunological and clinical benefits even after prolonged ZDV treatment had S/L-NSI viruses and a low risk to develop ZDV resistance. Conversely, subjects who demonstrated an immunological and clinical deterioration yielded R/H-SI variants or shifted from S/L-NSI to R/H-SI phenotypes and were at higher risk to develop mutations indicating ZDV resistance.

Orally administered ranitidine plasma concentrations before and after biliopancreatic diversion in morbidly obese patients.

BACKGROUND: Patients undergoing biliopancreatic diversion (BPD) may develop gastric ulcers, particularly within the first postoperative year. The prophylactic use of antisecretory compounds at the usual therapeutic doses, mainly conventional H2-receptor antagonists such as ranitidine, may reduce the incidence of this complication, which occurs in approximately 5% of patients after BPD. METHODS: The authors measured the plasma concentrations of ranitidine (300 mg orally) in obese patients, before and 8 months after BPD, and in control subjects of normal weight. The study included 11 obese patients undergoing BPD (age 45+/-14 years; preoperative and postoperative weights 124+/-21 and 92+/-11 kg) and 10 normal-weight subjects (age 37+/-13 years, weight 67+/-9 kg). RESULTS: Postoperative ranitidine plasma concentrations showed only minor differences from preoperative levels, with slightly higher maximum concentrations occurring sooner. The mean area under the curve was on the average 30% higher than preoperatively. All parameters, however, were similar to those in control subjects. CONCLUSIONS: BPD per se does not greatly affect the pharmacokinetic behavior of ranitidine, and therefore a conventional dosage regimen appears adequate for the prophylaxis and therapy of gastric ulcers associated with this operation.

Influence of dose and route of administration on the kinetics of fluoxetine and its metabolite norfluoxetine in the rat.

Fluoxetine (FL) is being used in neuropharmacology as a tool for studying various functional roles of serotoninergic neurons. Its kinetics was studied in rats, a species widely used in neurochemical studies, after IV (2.5-10 mg/kg) and oral (5-20 mg/kg) administration. When injected IV the drug followed apparent first-order kinetics up the 10 mg/kg dose. Its volume of distribution was large and total body clearance was relatively high compared to liver blood flow. The mean elimination half-lives (t1/2) of FL and its active metabolite norfluoxetine (NFL) were about 5 and 15 h, respectively. The mean blood:plasma concentration ratios of FL and NFL approached unity and plasma protein binding was 85-90% for both compounds. After oral doses the kinetics of FL were complex. At the lowest dose tested (5 mg/kg) the drug was efficiently extracted by the liver (extraction ratio about 60%), resulting in bioavailability of only about 38%. Plasma areas under the curve (AUC) of the metabolite were approximately the same as after IV injection of the same dose; consequently the metabolite-to-parent drug ratio after oral administration (about 5) was approximately twice that after IV injection of FL (about 2.5). At higher doses, however, the oral bioavailability (e.g. Cmax and AUC) appeared greater than expected, possibly because of transient saturation of FL first-pass metabolism in the case of the 10 mg/kg dose and concomitant saturation of elimination kinetics at the higher dose (20 mg/kg). The apparent elimination t1/2 of FL markedly increased and the metabolite-to-parent drug ratio declined with the higher dose, this also being consistent with saturable elimination.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of d-fenfluramine on the indole contents of the rat brain after treatment with different inducers of cytochrome P450 isoenzymes.

The effects of pretreatment with inducers of hepatic cytochrome P450 isoenzymes (phenobarbital, dexamethasone and beta-naphthoflavone) on the metabolism of d-fenfluramine (d-F) and its acute and long-lasting indole-depleting effects were studied in rats, in an effort to obtain further information on the importance of hepatic drug metabolism in relation to its neurochemical actions. Twenty-four hours after the last dose of each inducer, rats were injected with d-F hydrochloride (5 mg/kg, IP) and killed at various times thereafter for parallel determination of indoles and drug concentrations in plasma and brain. Additional rats were treated as above and killed 1 week after d-F hydrochloride (5 and 10 mg/kg) to study the recovery of indole in the cortex, a particularly sensitive brain area. Phenobarbital and beta-naphthoflavone and, to a lesser degree, dexamethasone, stimulated the metabolism of d-F, as evidenced by a decrease in plasma and brain areas under the curve (AUC) compared to vehicle-treated rats. This indicated that multiple isoenzymes are capable of mediating the drug's metabolism, primarily by N-dealkylation to d-norfenfluramine (d-NF). None of the inducers raised plasma and brain AUC of the nor-derivative, and in fact phenobarbital and particularly beta-naphthoflavone reduced it. These different effects were even apparent in rats given d-NF (2.5 mg/kg), indicating that both phenobarbital and beta-naphthoflavone also stimulate the sequential metabolism of the nor-metabolite (by N-deamintaion) which, however, is apparently enhanced most actively by beta-naphthoflavone-inducible forms of P-450.(ABSTRACT TRUNCATED AT 250 WORDS)