Decreased vesicular monoamine transporter 2 (VMAT2) and dopamine transporter (DAT) function in knockout mice affects aging of dopaminergic systems.

Dopamine (DA) is accumulated and compartmentalized by the dopamine transporter (DAT; SLC3A6) and the vesicular monoamine transporter 2 (VMAT2; SLC18A2). These transporters work at the plasma and vesicular membranes of dopaminergic neurons, respectively, and thus regulate levels of DA in neuronal compartments that include the extravesicular cytoplasmic compartment. DA in this compartment has been hypothesized to contribute to oxidative damage that can reduce the function of dopaminergic neurons in aging brains and may contribute to reductions in dopaminergic neurochemical markers, locomotor behavior and responses to dopaminergic drugs that are found in aged animals. The studies reported here examined aged mice with heterozygous deletions of VMAT2 or of DAT, which each reduce transporter expression to about 50% of levels found in wild-type (WT) mice. Aged mice displayed reduced locomotor responses under a variety of circumstances, including in response to locomotor stimulants, as well as changes in monoamine levels and metabolites in a regionally dependent manner. Several effects of aging were more pronounced in heterozygous VMAT2 knockout (KO) mice, including aging induced reductions in locomotion and reduced locomotor responses to cocaine. By contrast, some effects of aging were reduced or not observed in heterozygous DAT KO mice. These findings support the idea that altered DAT and VMAT2 expression affect age-related changes in dopaminergic function. These effects are most likely mediated by alterations in DA compartmentalization, and might be hypothesized to be exacerbated by other factors that affect the metabolism of cytosolic DA. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.

Global spread and genetic variants of the two CYP9M10 haplotype forms associated with insecticide resistance in Culex quinquefasciatus Say.

Insecticide resistance develops as a genetic factor (allele) conferring lower susceptibility to insecticides proliferates within a target insect population under strong positive selection. Intriguingly, a resistance allele pre-existing in a population often bears a series of further adaptive allelic variants through new mutations. This phenomenon occasionally results in replacement of the predominating resistance allele by fitter new derivatives, and consequently, development of greater resistance at the population level. The overexpression of the cytochrome P450 gene CYP9M10 is associated with pyrethroid resistance in the southern house mosquito Culex quinquefasciatus. Previously, we have found two genealogically related overexpressing CYP9M10 haplotypes, which differ in gene copy number (duplicated and non-duplicated). The duplicated haplotype was derived from the non-duplicated overproducer probably recently. In the present study, we investigated allelic series of CYP9M10 involved in three C. quinquefasciatus laboratory colonies recently collected from three different localities. Duplicated and non-duplicated overproducing haplotypes coexisted in African and Asian colonies indicating a global distribution of both haplotype lineages. The duplicated haplotypes both in the Asian and African colonies were associated with higher expression levels and stronger resistance than non-duplicated overproducing haplotypes. There were slight variation in expression level among the non-duplicated overproducing haplotypes. The nucleotide sequences in coding and upstream regions among members of this group also showed a little diversity. Non-duplicated overproducing haplotypes with relatively higher expression were genealogically closer to the duplicated haplotypes than the other non-duplicated overproducing haplotypes, suggesting multiple cis-acting mutations before duplication.

The VMAT2 gene in mice and humans: amphetamine responses, locomotion, cardiac arrhythmias, aging, and vulnerability to dopaminergic toxins.

Monoamine compartmentalization in monoaminergic neurons uses serial action of the plasma membrane and vesicular monoamine (VAMT2) transporters. We can now define the sequences of the genes encoding these transporters in mice and humans, examine influences of deletions of this gene and alteration in its expression levels in transgenic mice, and identify sequence polymorphisms in the human VMAT2 gene. Examination of VMAT2 variants can provide potential insights into roles for allelic variants at these loci in variant drug responses and in diseases linked to monoaminergic systems, including substance abuse and Parkinson's disease.

Heterozygous VMAT2 knockout mice display prolonged QT intervals: possible contributions to sudden death.

Heterozygous knockout (KO) mice with half of wild-type levels of expression of the vesicular monoamine transporter (VMAT2) can suddenly die in midlife. To seek mechanisms for this sudden death, we have examined electrocardiogram (ECG) data telemetered from freely-moving heterozygote and wild-type littermate mice. Many ECG parameters were indistinguishable in mice of these two strains. However, heterozygous mice displayed prolonged QT intervals. These findings provide likely contributions to differences in vulnerability to lethal arrhythmias in these animals, and a candidate gene for contributions to human interindividual differences in vulnerability to cardiac arrhythmias.

Effects of DU-6859a, a new quinolone antimicrobial, on theophylline metabolism in in vitro and in vivo studies.

In vitro and in vivo studies were conducted to investigate the drug interaction between a new quinolone antimicrobial, DU-6859a, and theophylline (TP). The effect of DU-6859a on TP metabolism was evaluated in vitro by measuring the rate of TP metabolite formation by using human liver microsomes. DU-6859a inhibited the metabolism of TP, especially the formation of 1-methylxanthine, in vitro, but to a lesser extent than other drugs that are known to interact with TP. TP was administered alone (200 mg twice a day [b.i.d.] for 9 days) or in combination with DU-6859a (50 or 100 mg b.i.d. for 5 days) to six healthy subjects. DU-6859a administered at a dose of 50 mg resulted in no changes in serum TP concentrations, and slight increases in serum TP concentrations were observed at a dose of 100 mg. Moreover, the administration of 100 mg of DU-6859a resulted in decreases in all urinary TP metabolites, with significant differences. It appears that although DU-6859a has a weak inhibitory effect on TP metabolism in vitro, its concomitant use with TP at clinical dosage levels does not cause any adverse effects, showing only a slight increase in blood TP concentrations and a decrease in urinary metabolites.

[A case of sympathotonic orthostatic hypotension following herpes simplex encephalitis].

The etiology of sympathotonic orthostatic hypotension (SOH) is still unknown. We reported a 50-year-old male case of SOH associated with herpes simplex encephalitis. Eight days before admission to our hospital, he noticed fever, which was followed by intractable hiccup. He was admitted to a local hospital, where nuchal rigidity and mononuclear CSF pleocytosis were noted. On the 9th hospital day, he suddenly developed respiratory arrest, and his consciousness state deteriorated to coma. He was transferred to our hospital with artificial ventilation on the same day. The second CSF examination revealed pleocytosis and positive herpes-simplex-virus antibody. CAT scan showed diffuse high density areas in the bilateral temporal lobes. Intensive anti-herpetic therapy was started. On the 14th hospital day, spontaneous respiration came back and consciousness state was improved from coma to stupor. He gradually recovered to alert state and became ambulatory by the 30th hospital day. Seven weeks after the onset of his illness, he noticed orthostatic dizziness for the first time during his rehabilitation exercises. Blood pressure was 116/78mmHg at supine position and 82/62mmHg at standing position, and the heart rate was 83bpm, and 141bpm, respectively. Plasma noradrenaline concentration was 0.09 ng/ml (within normal range) at supine position, but increased to 0.29ng/ml upon standing. Catecholamine infusion tests revealed hyposensitivity in beta 2-receptors; decrease in blood pressure in response to isoprenaline was blunted, while increase of blood pressure to noradrenaline was not impaired. Nerve conduction studies and sweating tests were normal. When he was discharged from our hospital on the 87th hospital day, he still had orthostatic symptoms. His complete recovery took full one year. Some authors claimed that SOH is an abortive form of acute autonomic neuropathy, while others postulated that it was due to unbalanced cardiovascular alpha- and beta-adrenoceptor functions. SOH of the present case seems to be caused by the central nervous lesions; especially, the brain stem involvement due to herpes simplex encephalitis may well be causing SOH.

[The dose-response study of sparfloxacin against skin and soft tissue structure infections in the field of surgery].

Sparfloxacin (SPFX), a new oral quinolone antimicrobial, was evaluated for the clinical efficacy against skin/soft tissue structural and osteomyelitic infections. SPFX was administered to a total of 101 patients with various infections such as infected atheroma, periproctal abscess, subcutaneous abscess, wound infections, felon, cellulitis, furuncle, pilonidal sinus, sappurative mastitis, lymphangitis, hemorrhoidal fistula, osteomyelitis. The clinical efficacy in the evaluable 101 cases was assessed by the physician in charge as excellent in 19 cases, good in 64, fair in 11 and poor in 7, the efficacy rate being 82.2%. In contrast, the clinical efficacy in 101 evaluable cases by the criteria of the committee as excellent in 36 cases, good in 45, fair in 8, and poor in 12, the efficacy rate being 80.2%. Clinical efficacy rating was not significantly difference between 200 mg/day group and 300 mg/day group. The bacteriological eradication rate was 86.5% in 53 cases with monomicrobial infection and 90.3% in 33 cases with polymicrobial infections. Of 18 cases whose infections were previously intractable with other drugs and treated thereafter with SPFX, 15 were judged in the efficacy as excellent or good. The side effects observed in 2 cases during the treatment were epigastralgia and nausea which were tolerable and did not require withdrawal of SPFX. No abnormal laboratory value was found in the several required tests. The MIC values measured for 108 strains (90.0%) of 120 clinical isolated of 35 species were lower than 0.78 microgram/ml.

[Therapeutic effect of a new human immunoglobulin SM-4300 on the severe infections in surgical patients].

A newly developed human immunoglobulin preparation for intravenous use, SM-4300, had been studied in the field of surgery. SM-4300 was administered to 2 patients with severe infection in the combined use with antibiotics. SM-4300 was considered to be a safe and effectively useful drug. One case with suspicious of septicaemia was excellent response to SM-4300, at a dosage of 2.5 g/day x 3, and another case with postoperative diffuse peritonitis was not effective at a dosage of 5.0 g/day x 1. No objective and subjective side effect and abnormal laboratory finding was observed in 2 cases.

[Clinical investigation of a long-acting amoxicillin preparation in patients with skin and soft-tissue infections].

A clinical investigation of a long-acting amoxicillin preparation (L-AMPC) in 82 patients (81 with skin and soft-tissue infections and 1 with osteomyelitis) gave the following results. Staphylococcus aureus and Staphylococcus epidermidis were most frequently detected organisms. With an inoculum of 10(6) cells/ml, the respective MICs for S. aureus and S. epidermidis were 1.56 micrograms/ml and 0.2 micrograms/ml. When evaluated by the doctors in charge, the overall effect was excellent in 23 patients, good in 46, fair in 7 and poor in 6, with an efficacy rate of 84.1%. The efficacy rate was as high as 75.0 approximately 95.5% in considerable numbers of patients with furuncle, felon, infectious sebaceous cyst, subcutaneous abscess, phlegmon or periproctic abscess. The effectiveness rate was 92.3% (12/13) in patients who did not respond to treatment with other antibiotics such as cephalexin. The standard criteria of overall effectiveness were newly established by the committee under the consideration of the clinical course of symptoms and absence or present of surgical procedure. When evaluated by the standard criteria, the overall effectiveness was excellent in 27 patients, good in 42, fair in 4 and poor in 9, with an efficacy rate of 84.1%. There were no significant differences between the evaluation by the doctors in charge and that by the standard criteria. The eradication rate of the organisms detected was 94.1% (64/68 patients); 85.7% for S. aureus (24/28 strains) and 100% for S. epidermidis (27/27 strains). No significant differences were noted between the patients with and without surgical procedure in clinical effectiveness or bacteriological efficacy. One patient had diarrhea of unknown cause. No abnormal changes due to L-AMPC were noted in any laboratory test. The usefulness rate was 76.8%. These findings indicate that L-AMPC in b.i.d. doses is safe and effective in skin and soft-tissue infections in surgery.