Effects of pre-motion electromyographic silent period on dynamic force exertion during a rapid ballistic movement in man

Summary The effects of pre-motion silent period (PSP) on dynamic force exertion were studied in ten healthy subjects performing ballistic elbow extensions. The experiments were designed to evaluate the significance of mean differences between the averaged dynamic force curves of two groups: PSP-presence groups and PSP-absence groups. The presence of PSP was judged quantitatively and automatically by means of a newly developed method using statistical analysis. The results indicated that there were two effects of PSP on dynamic force exertion: one was a reducing effect, observed prior to the movement; the other was a reinforcing effect, observed in the first part of the ballistic movement. The duration of the reinforcement was significantly correlated with the duration of the reducing effect of PSP. The findings suggested that the reinforcement of dynamic force may be produced by the pre-stretch of agonistic muscles caused by prior force reduction due to PSP occurrence. The fact that PSP plays an important role in dynamic force exertion suggests that PSP may be incorporated in the central motor control system designed to interrupt the background activity, to stretch the agonist and to reinforce the dynamic force.     

Increased release of glucuronoxylomannan antigen and induced phenotypic changes in Trichosporon asahii by repeated passage in mice

Clinically important fungi such as Candida albicans and Cryptococcus neoformans are known to undergo phenotypic changes after repeated subculture or passages in vivo. However, there are no reports describing this phenomenon in Trichosporon species. This study investigated whether in-vivo passages of environmental isolates of Trichosporon asahii in mice changes their phenotype; three environmental isolates and 14 clinical isolates (from deep-seated infections) were used. The shape of the colony and cell type were observed, and the titre of glucuronoxylomannan (GXM) antigen and concentration of (1-->3)-beta-D-glucan were measured for each isolate. Changes in these features were also examined after three passages of the environmental isolates in mice. The shape of colonies and cell types were clearly different in environmental and clinical isolates. Furthermore, the clinical isolates released significantly higher levels of GXM antigen than environmental isolates (titre: log2 9.4 SD 0.7 versus log2 5.4 SD 1.4). The phenotype of passaged isolates was significantly different from the original environmental isolates with respect to the morphology of colonies and cell type and GXM release (titre: log2 10.0 SD 0.7 versus log2 5.4 SD 1.4). These results suggest that the phenotypic changes in T. asahii occur as a result of in-vivo passages. This process may allow a proportion of the fungal population to escape eradication by the host immune system, as GXM antigen is considered to protect the fungi against phagocytosis by polymorphonuclear leucocytes and monocytes in vivo.     

Lymphocyte chemotaxis in inflammation. VII. Isolation and purification of chemotactic factors for T lymphocytes from PPD-induced delayed hypersensitivity skin reaction site in the guinea-pig

Four types of lymphocyte chemotactic factor (LCF-a, -b, -c and -d) could be isolated from extract of 24-hr-old delayed-type hypersensitivity (DTH) skin reaction sites induced with purified protein derivative (PPD) in guinea-pigs by gel filtration on Sephadex G-100 followed by chromatography with DEAE-Sephadex. Partially purified LCF-b was thought to be a heat-stable protein with a molecular weight (mol. wt.) of about 14,000. LCF-c separated from LCF-d by chromatography with DEAE-Sephadex was highly purified by chromatography with CM-Sephadex, immunoadsorbent chromatography coupled with anti-IgG antibody, and chromatofocusing in that order. It was considered to be a heat-labile protein with a mol. wt. of about 160,000 and with pI of 8.1 +/- 0.2. LCF-d first separated from LCF-c was also highly purified by chromatography with CM-Sephadex followed by preparative isotachophoresis. The factor was considered to be a heat-labile protein with a mol. wt. of approximately 300,000 and with pI of 6.2 +/- 0.2. These factors were similarly active for non-adherent cells (mostly T cells) but not for cells (mostly B cells) adherent to anti-IgG antibody-coated petri-dishes. Since LCF-a was active for B cells as described earlier, it is thus suggested that LCF-b, LCF-c and LCF-d may be important for T cell migration in the DTH site to PPD.     

Heparin-induced thrombocytopenia (HIT): pathogenesis, laboratory test, and treatment

Heparin-induced thrombocytopenia(HIT) due to immunological mechanisms is known as an important adverse reaction to heparin treatment, and heparin treatment should be applied while keeping in mind the risk of onset of HIT 5-14 days after the initiation of heparin. The presence of HIT had not been fully recognized in clinical practice in Japan despite the management of HIT being well confirmed in Western countries. Recognition of HIT has increased since argatroban, a direct thrombin inhibitor, obtained the approval of the FDA for prevention and treatment of HIT. Although the incidence of HIT in Japan has not yet been clarified, there is some evidence that HIT is encountered in critically ill patients undergoing heparin anticoagulation. Clinical diagnosis of HIT is performed by means of thrombocytopenia of a drop of 50% or 100 x 10(30/microl for 5 -14 days after starting heparin treatment. Confirmatory laboratory tests examine whether the patients have antibodies against heparin/PF4 complexes or not. Two assay tests for detecting heparin/PF4 complex antibodies are available in Japan. As a functional test, the heparin-induced platelet aggregation method is easily performed and the result is obtained in a short time. The result of the test has, however, been misleading due to the selection of donors. Low platelet activity of the donors on the addition of heparin induces a negative response in spite of positive antibodies in the sample. Before testing samples, it is important to check heparin reactivity of the donor's platelets. Enzyme immunoassay detecting the antibodies is available as a commercial kit. Sensitivity obtained by enzyme immunoassay is very high and often introduces false-positives. Careful attention to interpretation of the result is required. Treatment of HIT should be started at the time of recognition of thrombocytopenia while antibody testing for HIT is performed. As an alternative anticoagulant to heparin, argatroban should immediately be applied to avoid complication of thrombosis. Thrombocytopenia and hypercoagulability quickly recover to the preheparin level by the appropriate use of argatroban.     

Reduction of trimethylamine N-oxide by Escherichia coli as anaerobic respiration

E. coli was found to grow anaerobically on lactate in the presence of trimethylamine N-oxide (TMANO), reducing it to trimethylamine. Anaerobic growth on glucose was promoted in the presence of TMANO. When a culture grown in complex medium was transferred to defined medium, growth on glucose and ammonia took place in the presence of TMANO after consumption of complex nutrients introduced with the preculture, in contrast to growth in nitrate respiration. The amounts of ethanol, succinate, and lactate among the fermentation products were decreased and that of acetate was increased in the presence of TMANO. Formate generation was much reduced at pH 7.4, whereas stoichiometric formation of formate was observed in the absence of TMANO. Cells grown anaerobically in the presence of TMANO had a higher activity of amine N-oxide reductase than cells grown under other conditions. The content of cytochrome-558 was elevated in the presence of TMANO during growth in complex medium. Cytochrome c-552 found in cells grown in diluted complex medium or defined medium in the presence of TMANO was oxidized by TMANO in cell extracts. The molar growth yield on glucose was higher in the presence of TMANO than in its absence and lower than that in the presence of nitrate.     

Protective role of heme oxygenase-1 in renal ischemia

Oxidative stress, which has been implicated in the pathogenesis of ischemic renal injury, degrades heme proteins, such as cytochrome P450, and causes the elevation in the level of cellular free heme, which can catalyze the formation of reactive oxygen species. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is induced not only by its substrate, heme, but also by oxidative stress. In various models of oxidative tissue injuries, the induction of HO-1 confers protection on tissues from further damages by removing the prooxidant heme, or by virtue of the antioxidative, antiinflammatory, and/or antiapoptotic actions of one or more of the three products, i.e., carbon monoxide, biliverdin IXalpha, and iron by HO reaction. In contrast, the abrogation of HO-1 induction, or chemical inhibition of HO activity, abolishes its beneficial effect on the protection of tissues from oxidative damages. In this article, we review the protective role of HO-1 in renal ischemic injury, and its potential therapeutic applications. In addition, we summarize recent findings in the regulatory mechanism of ho-1 gene expression.     

Sequential changes in plasma lipoprotein(a) as acute phase protein after myocardial infarction and surgery group

The plasma lipoprotein(a), apo AI, apo B, and acute phase proteins, were studied in 21 patients with myocardial infarction and in 11 patients after surgery. In the both groups, C-reactive protein showed a rapid increase, and alpha 1 acid glycoprotein, alpha 1 antitrypsin and lipoprotein(a) followed by a moderate increase and restored to normal values after one month. Lipoprotein(a) increased to a maximum on day 11 in the myocardial infarction group, and on day 8 in the surgery group. Only slight changes in apolipoprotein AI and B were noted. We speculate that lipoprotein(a) is an acute phase protein that plays an important roles in recovery from trauma. Recently it was reported that the amino acid sequence of apolipoprotein(a) is partly identical to that of plasminogen. This sequence suggests that lipoprotein(a) and plasminogen are related immunochemically. We examined by immunoblotting technique whether our antibody for lipoprotein(a) is influenced by a plasminogen in plasma. By enzyme-linked immunosorbent assay, it was found that the purity of plasminogen does not influence determination of lipoprotein(a).     

HLA-DR Antigens in Pemphigus among Japanese

The frequency of HLA-DR4 was significantly increased at P < 0.02 in 37 unrelated pemphigus patients (62.2%), when compared with unrelated 73 healthy controls (30.1%). This antigen was more frequently found in pemphigus foliaceus (70.6%) than pemphigus vulgaris (55.8%).     

Effect of the hypocholesterolemic agent YM-16638 on cholesterol biosynthesis activity and apolipoprotein B secretion in HepG2 and monkey liver

YM-16638 ([[5-[[3-(4-acetyl-3-hydroxy-2-propylphenoxy)propyl]thio]-1,3,4-++ +thiadiazol-2-yl] thio] acetic acid) showed a strong hypocholesterolemic effect in humans and monkeys. To clarify the mechanism of this hypocholesterolemic effect, the action of YM-16638 on cholesterol biosynthesis in the cultured human hepatoma cell line HepG2 and cynomolgus monkey liver was examined. Cholesterol biosynthesis activity derived from [14C]acetic acid, [3H/14C]mevalonic acid or [14C]isopentenyl pyrophosphate substrates was significantly decreased, but not that from [3H]farnesyl pyrophosphate or [3H]squalene substrates in HepG2 cells treated with YM-16638. Simultaneously, treatment of these cells with YM-16638 changed neither the rate of apolipoprotein B synthesis from [35S]methionine nor its secretion. In addition, the activities of hepatic cholesterol biosynthesis enzymes HMG-CoA reductase, mevalonate kinase (MK), isopentenyl pyrophosphate isomerase (IPPI), farnesyl pyrophosphate synthase (FPPS), squalene synthase and squalene epoxidase were measured in monkeys fed a diet supplemented with YM-16638. Among these enzymes, MK, IPPI and FPPS activities in the YM-16638-treated group significantly decreased by 38%, 56% and 30%, respectively, when compared to those from control animals receiving no drug treatment. These results indicate that YM-16638 has the characteristics of a cholesterol biosynthesis inhibitor.     

Nuclear spheroids in neurons of the human hypothalamus]

Morphological structure, distribution and frequency of the so-called "nuclear spheroids" have been studied in the human hypothalamus. The following results were obtained: 1. By light microscopy, the nuclear spheroids turned out to be small or large spheroid bodies inside the nucleus. They are almost homogeneous, rarely granular, vacuolar or reticular and occasionally they are multiple. They are best stained with the cresyl-violet technique. They do not exhibit any histochemical pecularities. Aside from typical nuclear spheroids, irregularly shaped nuclei were frequently seen, associated with increased nuclear folds, transitional stages between nuclear folds and nuclear spheroids were also present. Certain microscopic features suggest invagination and displacement of nuclear membrane and cytoplasm into the karyoplasma. 2. By electron microscopy, the nuclear spheroids consist of nuclear membranes and cytoplasmic constituents. They, therefore, actually represent cytoplasm protruding into the cell nucleus. 3. The nuclear spheroids occur almost regularly and most frequently in the ventromedial field of the tuber cinereum, foremost in the infundibular (= arcuate) nucleus. They numerically increase during life. They are rarely found in the ventromedial nucleus but do occur in most of the adults. In the paraventricular nucleus, the supraoptic nucleus, the lateral nuclei tuberis, and in lateral hypothalamic nucleus, they are found by far less often. They scarcely develop in the preoptic area, in the dorsal field, in the tubero-mamillar complex, in the parafornical nuclear groups, in the premamillary nucleus and in the mamillary nuclei. 4. Within the infundibular (= arcuate) nucleus, the nuclear spheroids are particularly numerous in the basal and basolateral regions, whose neurons, under certain functional conditions--such as the Sheedan syndrome, in the menopause and in association with pituitary neoplasms-, appear hypertrophic. Within the hypertrophic neurons of this region, which we designate the subventricular part of the infundibular nucleus, nuclear spheroids are definitely more frequent, and they are of the large type. 5. A separation of the subventricular part based on the distributional pattern of the nuclear spheroids indicates a pathological karyoarchitectonics which supplements the normal karyoarchitectonics (Bachmann, 1948). 6. The nuclear spheroids seem to be associated with increased neuronal activities, for their frequently strongly correlates with the neuronal hypertrophy which expresses enhanced neuroendocrinological activity.