Arousal effect of orexin A depends on activation of the histaminergic system.

Orexin neurons are exclusively localized in the lateral hypothalamic area and project their fibers to the entire central nervous system, including the histaminergic tuberomammillary nucleus (TMN). Dysfunction of the orexin system results in the sleep disorder narcolepsy, but the role of orexin in physiological sleep-wake regulation and the mechanisms involved remain to be elucidated. Here we provide several lines of evidence that orexin A induces wakefulness by means of the TMN and histamine H(1) receptor (H1R). Perfusion of orexin A (5 and 25 pmol/min) for 1 hr into the TMN of rats through a microdialysis probe promptly increased wakefulness for 2 hr after starting the perfusion by 2.5- and 4-fold, respectively, concomitant with a reduction in rapid eye movement (REM) and non-REM sleep. Microdialysis studies showed that application of orexin A to the TMN increased histamine release from both the medial preoptic area and the frontal cortex by approximately 2-fold over the baseline for 80 to 160 min in a dose-dependent manner. Furthermore, infusion of orexin A (1.5 pmol/min) for 6 hr into the lateral ventricle of mice produced a significant increase in wakefulness during the 8 hr after starting infusion to the same level as the wakefulness observed during the active period in wild-type mice, but not at all in H1R gene knockout mice. These findings strongly indicate that the arousal effect of orexin A depends on the activation of histaminergic neurotransmission mediated by H1R.

Trimethoprim-sulfamethoxazole for the prevention of methicillin-resistant Staphylococcus aureus pneumonia in severely burned patients.

BACKGROUND: Patients with severe burns are at increased risk of developing methicillin-resistant Staphylococcus aureus (MRSA) ventilator-associated pneumonia. This study was designed to determine whether MRSA pneumonia can be prevented by prophylactic administration of trimethoprim-sulfamethoxazole (TMP-SMX). METHODS: We conducted a prospective, randomized, placebo-controlled study in patients with severe burns (> or = 20%), who required ventilator support. Prophylaxis was done with oral TMP-SMX (80 mg/400 mg) three times daily for 10 days from 4 to 6 days after burn injury. The incidence of MRSA pneumonia and the side effects were evaluated during the administration period. RESULTS: Twenty-one patients were assigned to receive TMP-SMX, and 19 patients to receive placebo. The incidence of MRSA pneumonia was 4.8% in the TMP-SMX group and 36.8% in the placebo group, showing a significant difference (p = 0.017). No major side effects of therapy were seen in the TMP-SMX group. CONCLUSION: Prophylactic treatment with TMP-SMX can prevent MRSA pneumonia in severely burned patients.

In vivo modulation of rat hypothalamic histamine release by the histamine H3 receptor ligands, immepip and clobenpropit. Effects of intrahypothalamic and peripheral application.

We investigated the effect of the new potent and selective histamine H3 receptor agonist, immepip, and the histamine H3 receptor antagonist, clobenpropit, on in vivo neuronal histamine release from the anterior hypothalamic area of urethane-anesthetized rats, using microdialysis. Intrahypothalamic perfusion with immepip at concentrations of 1 and 10 nM reduced histamine release to 75% and 35% of its basal level, respectively. Peripheral injection of immepip (5 mg/kg) caused a sustained decrease in histamine release of 50%. Clobenpropit potently increased histamine release after intrahypothalamic perfusion. The maximal increase in histamine release was 2-fold, observed at a concentration of 10 nM clobenpropit. Peripheral injection of clobenpropit (5-15 mg/kg) increased histamine release to about 150% of the basal value. A more marked increase in histamine release was found after injection of the histamine H3 receptor antagonist, thioperamide (5 mg/kg). In conclusion, intrahypothalamic perfusion of the histamine H3 receptor agonist, immepip and the histamine H3 receptor antagonist, clobenpropit, potently and oppositely modulated in vivo histamine release from the anterior hypothalamic area. The decreased histamine release after peripheral injection of immepip indicates that this novel agonist readily crosses the blood-brain barrier, making it a potential candidate for in vivo histamine H3 receptor studies. The differential increase in histamine release after peripheral injection of clobenpropit and thioperamide is discussed.

Thioperamide, a histamine H3 receptor antagonist, increases GABA release from the rat hypothalamus.

Using a microdialysis method and a new high performance liquid chromatography (HPLC)-fluorometric method for the detection of gamma-aminobutyric acid (GABA), we investigated the effect of thioperamide, an H3 receptor antagonist, on the GABA content in the dialysate from the anterior hypothalamic area of rats anesthetized with urethane. The addition of thioperamide to the perfusion fluid increased the release of GABA and histamine. Depleting neuronal histamine with alpha-fluoromethylhistidine, a specific inhibitor of histidine decarboxylase, and the administration of immepip, an H3 agonist, had no effect on basal- and thioperamide-induced GABA release. In addition, an infusion of clobenpropit, the most specific H3 receptor antagonist available, did not alter the basal release of GABA. On the other hand, histamine release was decreased by immepip and increased by thioperamide and clobenpropit. Removing Ca2+ from the perfusion fluid did not alter the effect of thioperamide on the GABA release, whereas that on histamine release was abrogated. These results suggest that the effect of thioperamide on GABA release is not mediated by histamine H3 receptors and that thioperamide acts on the transporter to cause an efflux of GABA from neurons and/or glia. Thioperamide is a popular H3 receptor antagonist which has been used applied to many studies. However, results using this compound should be interpreted in consideration of its effects on GABA release.

Alterations in ICAM-1 and ELAM-1 expression in psoriatic lesions following various treatments.

The expression of endothelial leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1) in psoriatic lesions was immunohistochemically examined before and after various single and combination therapies. The increased staining intensity of both adhesion molecules on the proliferated papillary venules in pretreated lesion was markedly reduced after cyclosporin-A monotherapy and etretinate therapy combined with oral eicosapentaenoic acid (EPA), psoralen plus ultraviolet-A radiation (PUVA) or ultraviolet-B radiation (UVB). Less pronounced alterations were observed with etretinate, EPA, PUVA, UVB, and topical corticosteroid alone. The epidermal expression of ICAM-1, on the other hand, faded out completely following any of the treatment measures. The findings suggest that cyclosporin-A monotherapy and the etretinate combination therapies have greater inhibitory effects on the endothelial expression of the adhesion molecules than the other monotherapies. Loss of the epidermal expression of ICAM-1 may be nonspecific to the treatment.

Species specificity of anticoagulant activity of activated human protein C: involvement of factor V as well as protein S.

Activated protein C (APC) possesses species specificity in its anticoagulant activity. Human APC exerts only weak activity in rat plasma compared with that in human plasma. The present study was undertaken to estimate the difference in interaction of human and rat factors with human APC and to assess the cause of the species specificity. Human or rat protein S (PS), factor V, or factor VIII was used to supplement human plasma depleted of each respective factor, and the anticoagulant activity of human APC was measured in term of the elongation of activated partial thromboplastin time (APTT). The activity of human APC in rat PS- or factor V-supplemented plasma was weaker than that in the human PS- or factor V-supplemented plasma. Furthermore, using purified human and rat factor V, human APC showed weaker inactivation of rat factor V than human factor V. Equal anticoagulant activity was observed in human or rat factor VIII-supplemented plasma. And there was a little difference in the interaction of APC with its inhibitors in human or rat plasma during a few minutes of incubation as judged by measurement of residual activity by an enzyme capture assay. From these results factor V as well as PS seems to play a major role in the species specificity of APC.

Protection of mice from Mycobacterium avium infection by recombinant interleukin-12.

Treatment with interleukin-12 (IL-12) significantly reduced the number of viable bacteria in mice infected with Mycobacterium avium. IL-12 itself, however, could not inhibit directly mycobacterial growth in vitro. IL-12 exerts antimycobacterial activity in vivo with a low level of toxicity, possibly by enhancing the host defense against the infection.

Daily intakes of fatty acids, sterols, and phospholipids by Japanese women and serum cholesterol.

The daily intakes of various lipids by 72 Japanese women (40-59 years of age) were measured directly from mock samples of food actually consumed (this method is similar to the duplicate portion method). One sample was collected from each of 12 subjects every 2-months for a period of 1 year. The daily intakes of total fatty acid (FA), cholesterol, plant sterol, phospholipid (PL), and phosphatidylcholine (PC) were 37.9 g, 300 mg, 152 mg, 3.1 g, and 1.7 g, respectively. No effect of the sampling period was found for any lipid measured. The combined eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids showed marked individual variation, and ranged from 0 to 4.3 g, and the average was 0.8 g. The n6/n3 polyunsaturated fatty acids (PUFA) ratio ranged from 0.9 to 19.1 (average, 4.2). There was a strong correlation only between cholesterol and PL intakes (r = 0.796, p < 0.05). The mean serum cholesterol, which was known in 42 subjects was 190 mg/dl, and showed no relation to their daily intakes of any of the measured lipids.

Interleukin-1 beta induces histamine release in the rat hypothalamus in vivo.

We have previously demonstrated the increase of histidine decarboxylase activity and histamine content in the murine hypothalamus after intracerebroventricular injection of lipopolysaccharide possibly due to inducible interleukin-1 beta (IL-1 beta). Therefore, we investigated the effects of IL-1 beta on brain histamine dynamics by directly injecting it into the tuberomammillary nucleus of the rat hypothalamus (TM) using an in vivo microdialysis method. Injection of artificial cerebrospinal fluid or recombinant murine IL-1 beta at 0.1 ng into the TM did not evoke a significant change in core temperature, however, a significant monophasic febrile response was observed following injection of IL-beta at more than 1 ng per animal. Histamine release in the anterior hypothalamic area in vivo was significantly augmented from 140 min to 360 min following injection of IL-1 beta at 10 ng dose. These results suggest the possibility that interrelationship between histamine and IL-1 beta may modulate the acute phase reaction in the central nervous system.

Increase of histidine decarboxylase activity in mice hypothalamus after intracerebroventricular administration of lipopolysaccharide.

The effect of intracerebroventricular (icv) administration of lipopolysaccharide on histidine decarboxylase activity and histamine content in the hypothalamus were investigated in male mice of ddY strain in vivo. Two-fold increase in histidine decarboxylase activity (HDC) was observed 4 h after administration of 50 mcg lipopolysaccharide, and HDC activity returned to the basal level within 12 h after injection. Furthermore, histamine contents showed a slight decrease at 1 and 2 h and a mild increase at 12 h after administration. However, changes in histamine content were not statistically significant. These results suggest that the increase of HDC activity in the hypothalamus by lipopolysaccharide may be involved in the central neuroimmune responses.

Gonadotropin-releasing hormone-associated peptide immunoreactivity in bovine colostrum.

Gonadotropin-releasing hormone(GnRH)-associated peptide (GAP) is a 56-amino acid peptide found on the C-terminal of the GnRH (also called luteinizing hormone-releasing hormone) precursor and is assumed to be co-produced with GnRH. The purpose of this report is to demonstrate the presence of GAP immunoreactivity in bovine colostrum. Radioimmunoassay of acidified methanolic extracts demonstrated a concentration of GAP immunoreactivity of approximately 1.5 +/- 0.1 pmol/g dry skim bovine colostrum. Gel filtration (Sephadex G-10) and high-performance liquid chromatography of extracts containing GAP immunoreactivity showed it to be of low molecular weight and a high hydrophobic character. The presence of GAP immunoreactivity in bovine colostrum suggests that the GnRH precursor is synthesized and processed in mammary tissue itself.

[Bombesin effects on the lateral hypothalamic and gastric acid secretory system in the rat (author's transl)].

Gastrosecretory effects of intravenous administration, and microinjection and electro-osmotic application into the lateral hypothalamus (LHA) were investigated in the case of bombesin, alone and concomitant administration with insulin or 2-deoxy-D-glucose (2-DG). Bombesin, a tetradecapeptide found in the brain and gastrointestinal tract of mammals, is a potent gastrin releasing factor. At doses below the threshold of gastric secretion, bombesin produced a decrease in latency and an increase in the amount of insulin-induced gastric acid secretion. In the LHA, microinjections and electro-osmotic applications had similar effects but did not affect secretion when given alone, yet reduced the latency and increased the amount of insulin-induced acid secretion. LHA neuronal activity was also unaffected by electro-osmotic application of bombesin alone, but this compound enhanced the excitatory effects of both insulin and/or 2-DG. Thus, the gastric secretory effects of bombesin appear to be local. This peptide modulates LHA-gastrosecretory mechanism but it is ineffective when administered alone.U

The isolation and characterization of a lethal protein from Kintoki beans (Phaseolus vulgaris).

A lethal protein with hemagglutinating activity but without trypsin inhibitory activity was isolated from beans of Phaseolus vulgaris, cultiva, and Kintoki and proved homogeneous by ultracentrifugation, disc polyacrylamide gel electrophoresis, sodium dodesyl sulfate polyacrylamide gel electrophoresis and isoelectric focusing. The molecular weight was estimated to be 104, 000 by ultracentrifugal analysis and gel filtration on Sephadex G-200. The molecule dissociates into three identical subunits in the presence of 8 M urea or 0.1% sodium dodesyl sulfate. The amino acid composition was characterized by the high content of aspartic acid and the complete absence of methionine and cystine. The carbohydrate content was 8.1%; 5.0% mannose and 3.1% glucosamine. The addition of the lethal protein to a basal diet (0.4%) resulted in the intensive depression of the growth and finally in the death of rats. The intraperitoneal injection of 250 microgram per g body weight of mouse brought about an acute toxicity which caused death of all the injected mice.