GABA(A) receptor-mediated inspiratory termination evoked by vagal stimulation in decerebrate cats.

To identify the GABAergic inhibitory mechanisms involved in inspiratory termination or off-switching (IOS), the effects of a specific enhancer of GABA(A) receptors, midazolam, and an antagonist, bicuculline, on vagally evoked inspiratory inhibitions and IOS were investigated in decerebrate cats. Stimulation of vagal afferents at late inspiration provoked either reversible inspiratory inhibition or IOS, depending on the stimulus intensity. Each response occurred at a constant latency (phase 1). The reversible response was triphasic, consisting of an early (phase 2) inhibition, a brief (phase 3) excitation and a late (phase 4) inhibition in the phrenic neurogram, and early (phase 2) IPSPs, brief (phase 3) EPSPs and late (phase 4) IPSPs in bulbar inspiratory (I) neurones. With an increasing stimulus intensity, phase 4 inhibitions were increased in amplitude and duration, leading to IOS. Midazolam (0.1 mg/kg i.v.) increased more selectively phase 4 IPSPs than phase 2 IPSPs in I neurones, and decreased the threshold for evoking IOS by producing an earlier and larger phase 4 IPSPs. Bicuculline (1.0 mg/kg i.v.) had an opposite effect. These results suggest that the late inhibitory response evoked by vagal stimulation in the I neuronal pool organizes an initial phase of IOS which is mediated by GABA(A) receptors.     

Laboratory data in healthy volunteers: reference values, reference changes, screening and laboratory adverse event limits in Phase I clinical trials

Objective: Laboratory data are key evaluation procedures for Phase I clinical pharmacology for two reasons. Firstly, laboratory data are used within the screening process to exclude subjects with asymptomatic diseases, which could result in increased danger to themselves or confuse interpretation of the study results. Secondly, during study implementation, safety evaluation and in particular maximum tolerated dose determination have to be done by a case-by-case analysis, sometimes using laboratory adverse events (LAEs). Thus, relevant limits are needed to discriminate between a usual common variation and a significant abnormality, which is considered to be a LAE. This report presents laboratory data distribution, reference values and reference changes and, based on previously published new methods, suggests inclusion limits at screening and laboratory adverse event limits for analysis during study implementation. Subjects and methods: Nine hundred and twenty-seven young healthy male volunteers were recruited in one centre (Association de Recherche Thérapeutique). A standard screening process was carried out. Protocols were approved by the local ethics committee. Blood sampling was performed in the same conditions. Reference values (at screening and at baseline) were determined by a non-parametric procedure selecting 2.5% and 97.5% of the distribution of data. Reference changes were also defined as the 2.5–97.5% interval of distribution of the variations between the end of treatment and baseline. Inclusion limit and LAE limit methods of determination used had been specified in previous articles. Results: Detailed results of laboratory data distribution, reference values at screening and at baseline, reference changes, inclusion limits and LAE limits are presented in tables with number of subjects, mean, median, standard deviation, minimal and maximal values and the 2.5–97.5% interval for each laboratory parameter. Conclusion: The key aims of this paper are to provide clinical pharmacologists with data, reference values or changes obtained in the real conditions of Phase I study implementation, and to propose relevant limits, either for screening as inclusion limits, or during studies as LAE limits. Thus, these data, reference values and specific limits improve the capacity to screen healthy volunteers and to analyse LAEs during Phase I studies. Received: 30 July 1998 / Accepted in revised form: 25 November 1998     

Immunolocalization of prolyl 4-hydroxylase in fibroblasts cultured from Tenon's capsule of humans

Background: The excessive accumulation of extracellular matrix (ECM) with the repopulation of fibroblasts may lead to an unsuccessful outcome of glaucoma filtering surgery. We examined the immunolocalization of ECM components and prolyl 4-hydroxylase, an enzyme involved in collagen biosynthesis, in cultured Tenon's capsule fibroblasts (TCFs) of humans to evaluate the production of ECM in the cells. Methods: We used light microscopy to evaluate the immunolocalization of prolyl 4-hydroxylase and ECM components, collagen types I, III, and IV, cellular fibronectin, and laminin in TCFs. Ultrastructural localization of the enzyme was also evaluated by electron microscopy. Results: Immunoreactivity with monoclonal antibodies against the and subunits of the enzyme or with the polyclonal antibody against it was detected in the cytoplasm of the cells in a fine granular pattern, indicating its localization in the indoplasmic reticulum (ER). Immunoreactivity for the enzyme was detected in the cisternae of the ER on electron microscopy. Types I and III collagen reactivities were also observed in the cytoplasm in a fine granular pattern. T reactivity was present diffusely on the cell surface. The distribution of laminin reactivity in the cytoplasm resembled that of types I and III collagen. Cellular fibronectin reactivity was observed in the ECM in a reticular pattern. Conclusion: Prolyl 4-hydroxylase was located in the cisternae of the ER. TCFs produced a variety of ECM components in vitro. The results provide insight into the fibrotic process during scar formation at the site of a bleb following filtering surgery.     

Is growth hormone a feasible adjuvant in the treatment of children after small bowel resection?

The aim of our study was to assess the metabolic consequences of short-term administration of growth hormone in children after gut resection and influence on polyamine production in red blood cells (RBC). Twelve children aged 4-60 months were studied. All children remained on parenteral nutrition and 11 also received oral feeding. Total non-protein energy intake was 429 +/- 86 kJ/kg body weight (BW)/day. Recombinant growth hormone (GH) was administered subcutaneously at a dose of 0.3 IU/kg BW/day for 10 days. Resting energy expenditure (REE; kJ/kg BW/day) was: 316.07 +/- 54.08 before and 346.04 +/- 54.40 during GH administration (P < 0.02), but daily weight gain before GH administration was significantly lower than during treatment. A significant increase of polyamine concentrations was observed in the RBC (spermidine: 30.1 +/- 15.1 and 43.8 +/- 24.9 nmol/ml packed RBC, P < 0.003; spermine: 15.6 +/- 5.1 and 19.6 +/- 10.6 nmol/ml packed RBC, P < 0.02) and in jejunal mucosa (spermidine: 172.10 +/- 142.35 nmol/g tissue and 193.92 +/- 108.15 nmol/g tissue). The authors concluded that increased polyamine concentrations in the RBC and jejunal mucosa reflect a cellular response to GH administration. The anabolic effect of GH results in higher weight gain, although increased REE may indicate increased energy requirements during GH treatment.     

Δ9-THC as a discriminative stimulus in rats and pigeons: Generalization to THC metabolites and SP-111

In a drug discrimination paradigm pigeons and rats were trained with an operant procedure to discriminate between the presence and absence of the effects of ⁹-THC (1.0 and 3.0 mg/kg, injected IM 90 min and I.P. 30 min before the start of the session). Once trained, various THC metabolites as well as a water-soluble derivative of THC (SP-111), were substituted for ⁹-THC to test for generalization to the training drug. Generalization to ⁹-THC occurred with the 11-hydroxy metabolites and the potency order was 11-OH-⁹-THC >11-OH-⁸-THC ⁹-THC. Among the other metabolites tested (8-OH-⁹-THC, 8, 11-di-OH-⁹-THC, 8-OH-⁹-THC, 8, 11-di-OH-⁹-THC), it was only 11-di-OH-⁹-THC that completely substituted for ⁹-THC in pigeons, albeit at very high dose levels (rats were not tested with these metabolites). SP-111 generalized to ⁹-THC in both species. However, the onset of action of SP-111 was slower than that for ⁹-THC, especially in pigeons. These studies show the importance of obtaining complete dose-effect determinations over time when assessing structure-activity relationships with drug-discrimination procedures.A brief account of the results, which are summarized in Neuropharmacology 18:1023–1024, 1979), was presented at the British Association for Psychopharmacology Summer Conference, July 15–17, Birmingham, England, 1979     

Urinaryβ 2-microglobulin and renal functions in elderly people in an area with no known cadmium pollution (Japan)

Urinary0437n78/xxlarge914.gif" alt="Bgr" align="BASELINE" BORDER="0"> ₂-microglobulin (MG) was determined in 99 elderly people above 50 years of age from an area with no known cadmium pollution. With advancing age, the urinary MG increased as well as the urinary protein, urinary retinol-binding protein (RBP), and plasma urea nitrogen. Nevertheless, age effects were not observed in renal functions such as creatinine clearance or tubular reabsorption of phosphorus. Analysis of the relationship between urinary MG and parameters of the renal functions suggested 2-step increases in urinary MG: a slight increase between 160 and 16000437n78/xxlarge924.gif" alt="Mgr" align="BASELINE" BORDER="0">g/L and a remarkable increase above 16000437n78/xxlarge924.gif" alt="Mgr" align="BASELINE" BORDER="0">g/L. The latter strong increase in urinary MG was closely related with depressed tubular reabsorption of MG, but was independent of tubular reabsorption of phosphorus. The screening level of urinary MG for renal tubular dysfunction is suggested at 16000437n78/xxlarge924.gif" alt="Mgr" align="BASELINE" BORDER="0">g/L.     

Controlled trial of thyrotropin releasing hormone tartrate in ataxia of spinocerebellar degenerations

The clinical efficacy, dose-response relationship, and safety of TRH-T (thyrotropin releasing hormone tartrate) were assessed in 290 patients with spinocerebellar degeneration (SCD) in a 2-week, double-blind study using placebo as control. 254 patients satisfied the criteria for inclusion in evaluation of the drug efficacy. The patients were treated with TRH-T in an intramuscular dose of 2 mg, 0.5 mg or 0 mg (placebo) as TRH once a day for 2 weeks. Clinical responses to these treatments were evaluated 3 times: at the end of weeks 1 and 2 of treatment and a week after the end of treatment. The results of "global improvement rating" as well as those of "ataxia improvement rating" showed that both 2 mg and 0.5 mg TRH-T treatments were significantly superior to placebo treatment in patients with predominantly cerebellar form of SCD. The effect was well maintained a week after the end of the 2-week treatment in the patients who were given TRH-T in daily dose of 2 mg and showed improvement at the end of treatment. The results of "improvement rating of each symptom" revealed that 2 mg treatment was significantly more effective than placebo for disorders of standing, gait, speech and writing. In the patients who had no pyramidal involvement or disorder of deep sensation, the drug efficacy and dose-response relationship were evident. Adverse reactions to the drug such as headache, feeling febrile and nausea were observed in 50% of the patients on 2 mg treatment, in 38% of those on 0.5 mg treatment and in 21% of those on placebo patient, however, discontinued treatment because of adverse reactions.     

Liposomes and Nanoparticles in the Treatment of Intracellular Bacterial Infections

The treatment of infections caused by obligate or facultative intracellular microorganisms is difficult because most of the available antibiotics have either poor intracellular diffusion and retention or reduced activity at the acidic pH of the lysosomes. The need for antibiotics with greater intracellular efficacy led to the development of endocytosable drug carriers, such as liposomes and nanoparticles, which mimic the entry path of the bacteria by penetrating the cells into phagosomes or lysosomes. This Review assesses the potential of liposomes and nanoparticles in the targeted antibiotic therapy of intracellular bacterial infections and diseases and the pharmaceutical advantages and limitations of these submicron delivery systems.     

Oxidative damage on DNA induced by asbestos and man-made fibers in vitro

Summary We compared the potential of asbestos and man-made fibers to attack DNA by the determination of the yield of 8-hydroxy-2-deoxyguanosine (8-OH-dGuo) under several in vitro conditions. Asbestos induced 6.6–99.8 of 8-OH-dGuo per 10⁵ dGuo in calf thymus DNA after 20 h of incubation, while the levels of 8-OH-dGuo in man-made fibers were low (3.6–9.4). The amounts of 8-OH-dGuo were strongly stimulated by the addition of H₂O₂ in asbestos, but not in man-made fibers. However, the yield of 8-OH-dGuo was induced more than that with asbestos by the further addition of FeSO₄ in attapulgite, fiberglass, potassium titanate whisker, and metaphosphate polymer. The addition of ethylene diamine tetraacetic acid (EDTA) promoted the induction of 8-OH-dGuo with asbestos and H₂O₂. The effects of mannitol (known as a hydroxy radical scavenger) were not dramatic on 8-OH-dGuo induction by all fibers except fiberglass and basic magnesium sulfate whisker, which induced higher amounts after mannitol addition than in these fibers and H₂O₂. Therefore, it was suggested that asbestos could damage DNA, resulting in 8-OH-dGuo as a cause of point mutation, and also several types of manmade fibers had similar effects to asbestos under certain conditions.     

Different patterns of spleen involvement in systemic and malignant mastocytosis

Summary Three cases of splenic involvement in three different types of generalized mastocytosis (systemic mast cell disease) are reported. The macroscopic, histological and ultrastructural modifications of the spleen are described. Each case exhibited a different morphological pattern. Giemsa staining, fluorescence after acridine orange staining and naphthol ASD chloracetate esterase reaction are shown to be valuable for diagnosis. By comparison, immunohistochemistry seemed not to be very useful, because no specific antigens are expressed. These findings are compared to previously published cases. Their value for the diagnosis and the prognosis are discussed.