A region of the sulfonylurea receptor critical for a modulation of ATP-sensitive K(+) channels by G-protein betagamma-subunits.

To determine the interaction site(s) of ATP-sensitive K(+) (K(ATP)) channels for G-proteins, sulfonylurea receptor (SUR2A or SUR1) and pore-forming (Kir6.2) subunits were reconstituted in the mammalian cell line, COS-7. Intracellular application of the G-protein betagamma2-subunits (G(betagamma)(2)) caused a reduction of ATP-induced inhibition of Kir6.2/SUR channel activities by lessening the ATP sensitivity of the channels. G(betagamma)(2) bound in vitro to both intracellular (loop-NBD) and C-terminal segments of SUR2A, each containing a nucleotide-binding domain (NBD). Furthermore, a single amino acid substitution in the loop-NBD of SUR (Arg656Ala in SUR2A or Arg665Ala in SUR1) abolished the G(betagamma)(2)-dependent alteration of the channel activities. These findings provide evidence that G(betagamma) modulates K(ATP) channels through a direct interaction with the loop-NBD of SUR.

Association of neonatal hyperbilirubinemia with bilirubin UDP-glucuronosyltransferase polymorphism.

OBJECTIVE: The incidence of nonphysiologic neonatal hyperbilirubinemia is twice as high in East Asians as in whites. We studied whether the condition was associated with mutations in the gene for bilirubin uridine 5'-diphosphate-glucuronosyltransferase (UGT1A1), a key enzyme of bilirubin catabolism. DESIGN: We analyzed the UGT1A1 gene in 25 Japanese neonates who had nonphysiologic hyperbilirubinemia (serum bilirubin >257 micromol/L) with no obvious cause. They had all received phototherapy. The background control population consisted of 50 Japanese neonates whose transcutaneous jaundice index was monitored during the first week of life. We detected mutations by direct sequencing of polymerase chain reaction-amplified fragments of the gene. RESULTS: We found a polymorphism for UGT1A1 in exon 1; a G-->A transition at nucleotide 211 caused arginine to replace glycine at position 71 of corresponding protein product (G71R). The frequency of the mutated allele in the hyperbilirubinemic group (0.34) was significantly higher (chi2 = 5.56) than in the control group (0.16). In the control group the peak transcutaneous jaundice index of the carriers of G71R was significantly higher than it was in the normal infants. CONCLUSIONS: The missense mutation causing G71R is the first reported polymorphism for UGT1A1, and the mutation is a risk factor for nonphysiologic neonatal hyperbilirubinemia. The high incidence of hyperbilirubinemia in the Japanese may be attributable to the high frequency of this missense mutation.

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.

Effects of Kamikihi-To, a traditional Chinese medicine, on behavioral changes induced by methyl-beta-carboline-3-carboxylate in mice and rats.

The effects of Kamikihi-To (KMK), a traditional Chinese medicine, on behavioral changes induced by methyl-beta-carboline-3-carboxylate (beta-CCM) were evaluated in mice and rats. Beta-CCM, an anxiogenic benzodiazepine receptor inverse agonist (3.0 mg/kg, i.v. administered 1 min before the test), decreased the locomotor activity of mice in a novel environment. Furthermore, beta-CCM (0.1 mg/kg, i.v. administered 10 min before the test) facilitated the suppression of drinking behavior induced by punishment in the water lick conflict test in rats. KMK (1.0 and 2.0 g/kg, p.o. administered 1 hr before the test) antagonized the decreased locomotor activity in the beta-CCM-treated mice. KMK (2.0 g/kg, p.o.) also recovered the suppression of drinking behavior in the beta-CCM-treated rats. KMK (2.0 g/kg, p.o.) had no effect on beta-CCM-untreated mice and rats in these tests. These findings suggest that KMK has a protective effect against beta-CCM-induced behavioral changes.

[Effects of kamikihi-to on ovariectomy-induced changes in behavior and circulation in rats].

The various symptoms that women experience in the climacteric period, such as flashing, depression, paresthesia and insomnia, have been termed the menopausal syndrome. Since Kamikihi-to (KMK) has been administered clinically for several of these symptoms, the effects of KMK were evaluated in a series of experiments using adult ovariectomized (OVX) rats. After surgery, KMK and other drugs were administered daily for 7 or 8 days until the experiments. OVX rats showed significantly higher electric shock thresholds, and KMK restored their sensitivity to electric shock in a dose-dependent manner. Furthermore, the latency of OVX rats in the step-through passive avoidance test was significantly shortened, and KMK prolonged the latency significantly. OVX rats showed a significantly decreased number of correct choices and an increased number of errors in the 8-arm radial maze task, and KMK normalized both of these parameters in a dose-dependent manner. The blood pressure of OVX rats was significantly increased, and KMK improved the blood pressure levels. These findings suggest that KMK might be useful for treatment of the menopausal syndrome, and it is considered that the improvements induced by KMK are due to other actions, such as normalization of the central nervous system, rather than sex hormones.

[Antinociceptive effects of Kami-kihi-to in mice].

Oral administration of Kami-kihi-to (KMK) dose-dependently inhibited the response to acetic acid-induced writhing in mice. The KMK-induced antinociceptive action was reduced by pretreatment with yohimbine, an alpha 2-adrenergic antagonist, or cyproheptadine, a serotonergic antagonist, but not naloxone, an opiate antagonist. The antinociceptive action of KMK was clearly reduced by pretreatment with alpha-methyl-DL-p-tyrosine, reserpine or p-chlorophenylalanine or by simultaneous treatment with diethyldithiocarbamate, all of which are monoamine synthetic inhibitors or monoamine depletors. After spinal transection, the antinociceptive effect of KMK was markedly reduced. These findings suggest that the antinociceptive action of KMK may be related to pain inhibitory systems such as the serotonergic and noradrenergic systems at the supraspinal level.

Protective effects of kamikihi-to, a traditional Chinese medicine, against cerebral ischemia, hypoxia and anoxia in mice and gerbils.

The protective effects of Kamikihi-To (KMK), a traditional Chinese medicine, against cerebral ischemia, hypoxia and anoxia were investigated with various experimental models in mice and gerbils. KMK (2.0 g/kg/day, p.o. for 5 days) significantly prolonged the survival time of mice subjected to bilateral common carotid artery occlusion. KMK (0.5 and 2.0 g/kg/day, p.o. for 5 days) also prolonged the survival time of mice injected with N-methyl-D-aspartic acid (NMDA: 80 mg/kg, i.v.). Furthermore, KMK (in a diet containing 8% KMK given orally for 34 days) showed protective effects against delayed neuronal death in CA1 pyramidal cells in the gerbil hippocampus after transient forebrain ischemia. On the other hand, we failed to show any protective effects of KMK (0.5-2.0 g/kg/day, p.o. for 5 days) against normobaric hypoxia and KCN-induced cytotoxic anoxia in mice. These results suggest that KMK may have protective effects against cerebral ischemic disorders, but not against severe hypoxic and anoxic disorders.

[Effects of Kamikihi-To on autonomic imbalances in SART-stressed (repeated cold-stressed) mice].

The effects of Kamikihi-To (KMK), a traditional Chinese medicine, on autonomic imbalances were evaluated in SART-stressed (repeated cold-stressed) mice. These animals exhibited decreases in pain threshold and contraction of duodenum by acetylcholine, and they showed changes in their electrocardiogram and hematological parameters. All symptoms are thought to be caused by dysautonomia. KMK in dosages of 0.5 and 1.0 g/kg were administered to mice once a day for 8 consecutive days. SART stress was induced from the second day. KMK prevented the decrease in the pain threshold and contraction of the duodenum, although it had no effect on the electrocardiographic or hematological changes. KMK had no similar effect on unstressed mice. This data suggests that KMK might be useful for the treatment of clinical autonomic imbalances.

Effects of Kamikihi-To, a traditional Chinese medicine, on passive and conditioned avoidance performance impairment in senescence accelerated mouse (SAM).

Effects of Kamikihi-To (KMK), a traditional Chinese medicine (Chinese name: Jia-Wei-Gui-Pi-Tang), on learning performance impairment caused by aging were evaluated in senescence accelerated mice (SAM). Normal diet containing 8% KMK extract was given to SAM-P/8, a senile-prone strain and to SAM-R/1, a resistant strain, from 2 months old. Effects of KMK on learning performance were evaluated in 5 and 10 month old SAM using step through and step down type passive avoidance tests and shuttle box and lever press type conditioned avoidance tests. At 5 months old KMK increased the retention rate in the step through test and decreased the number of errors in the step down test in SAM-P/8, though KMK had no effects in conditioned avoidance tests. KMK had no effects in any tests in SAM-R/1. At 10 months old, the decrease in the number of errors in the step down test and increase of the rate of the conditioned avoidance response in the shuttle box test were observed in SAM-P/8 treated with KMK. These results suggest that chronic administration of KMK can improve learning performance in the senescence model.