Search PubMed⌕ Search

Biomedical subjects

K Muramatsu

Publications and source records attributed to K Muramatsu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Topography of hypoxic injury proved by argyrophilia in postnatal rat brain.

The argyrophil III method, a new esterification-silver staining approach, was used to elucidate regional differences in the susceptibility of developing brain to hypoxic-ischemic (H-I) injury. We created a unilateral common carotid artery-ligation model with hypoxia (8% oxygen) in postnatal day (P) 7, P14 and P21 rats. The argyrophil (i.e., deteriorated) neurons were apparent in the ipsilateral hippocampus, cortex, and striatum in each age group. Argyrophil neurons exhibited some morphological signs of the "early phase" of injury preceding the loss of structure and/or cell death in the "late phase," as indicated by hematoxylin-eosin (H-E) staining. The argyrophil neurons were apparent as early as 12 hours after the insult, whereas the histological changes revealed by H-E staining were subtle. The early phase and late phase histological changes had a stereotyped pattern of appearance in all ages studied. However, the duration of H-I situation required to produce argyrophil cells differed according to age. The most resistive age was P14 (P14 > P7 > P21) in this observation. Therefore, argyrophil III staining is feasible for H-I brain damage model in neonates. The results suggest that both the early phase and the late phase pathological processes after H-I injury have a characteristic topographical vulnerability that does not change during development but have a differing susceptibility according to age.

Animals↗
PubMed1997

Vulnerability to cerebral hypoxic-ischemic insult in neonatal but not in adult rats is in parallel with disruption of the blood-brain barrier.

BACKGROUND AND PURPOSE: Vulnerability to cerebral hypoxic-ischemic (H-I) insult and its relation to disruption of the blood-brain barrier were investigated in postnatal rats. METHODS: Pups of postnatal day (P) 7, P14, and P21 underwent ligation of a unilateral carotid artery and were exposed to hypoxic conditions. For the detection of early-phase deterioration, brains were perfusion-fixed 24 hours after H-I insult and examined by argyrophil III method. For the detection of later infarction, animals were fixed at 72 hours after the H-I insult. RESULTS: In either case, tissue damage was detected in the striatum, parietal cortex, and hippocampus. The vulnerability of P7 and P21 rats was remarkable, as compared with P14 rats. Although the developmental status of the vasculature was not significantly different at each age, the permeability of IgG after H-I injury was prominent in P7 rats and to a lesser extent in P14 rats. In P21 rats, however, there was little IgG leakage even 24 hours after the insult. Dexamethasone pretreatment blocked the extravasation of IgG and reduced the damaged tissue in P7 and P14 rats but not in P21 rats. Percentages of reduction in infarcted areas by the dexamethasone became smaller in proportion to ages. CONCLUSIONS: The results suggest that in younger rats vulnerability to H-I insult was in parallel with permeability of the blood-brain barrier, whereas in adults in might be more dependent on cellular vulnerability.

Aging↗
PubMed1997

Longer survival of rat limb allograft. Combined immunosuppression of FK-506 and 15-deoxyspergualin.

We studied the individual and synergistic effect of 3 immunosuppressive drugs, FK-506 (1 mg/kg/day), 15-deoxyspergualin (2.5 mg/kg/day) and cyclosporine (15 mg/kg/day) in a DA/Lewis rat limb allotransplantation model. 74 right hindlimb transplantations were performed. The median time for onset of rejection was 4 days in animals without immunosuppression, 37 days in animals receiving cyclosporine immunosuppression for 30 days, 61 days in animals receiving FK-506 for 30 days, 36 days in animals receiving a 30-day course of cyclosporine and, in the first 15 days, a course of 15-deoxyspergualin, and 76 days in animals receiving a 30-day course of FK-506 and 15-deoxyspergualin in the first 15 days. The combination of cyclosporine with 15-deoxyspergualin did not prolong graft survival and no synergistic effect was evident. In contrast, survival time in rat limb allografts receiving FK-506 and 15-deoxyspergualin was longer than in those receiving single FK-506 therapy. Our findings suggest a positive synergistic immunosuppressive effect with FK-506 and 15-deoxyspergualin in limb allotransplantation.

Animals↗
PubMed1996

Labeling and identification of living donor cells in brain slices of recipient hemiparkinsonian model rats for physiological recordings: methods for physiological assessments of neural transplantation.

Physiological properties of grafted neurons, such as membrane and intr acellular properties, have not been reported. To fill this lack in knowledge, physiological recordings from the identified grafted cells are required. Fluorescent latex microspheres (FLM) are non-toxic and stable, and thus seem suitable for long-term labeling of donor cells. Therefore, we tested the feasibility of labeling with FLM to identify living donor cells in the recipients' brain slices. We also tested if physiological recordings from the identified cells are possible or not. Cell suspensions were prepared from the substantia nigra (SN) of Embryonic Days 15 or 16 rats with enzymatic and mechanical trituration. Cell suspensions were then incubated with 0.5% FLM for 30 min to 2 h. The longer cells were incubated, the more FLM were taken up. The FLM-labeled SN cell suspensions were injected in the striatum of the hemiparkinsonian model rats. Eight to 13 weeks later, 150-mu m thick coronal brain slices including the graft track were prepared from the recipients. Slices were kept in vitro for several hours. Grafted cells could be clearly identified in the slice preparations by the uptake of FLM under a fluorescence microscope. Voltage-dependent currents and intracellular Ca2+ transcients were successfully recorded from the identified grafted neurons. It is suggested that labeling and identification of living donor cells with FLM is feasible and thus can provide a powerful tool to study the mechanisms underlying graft-induced amelioration of neurological deficits in parkinsonism by enabling physiological assessments of grafted cells.

Animals↗
PubMed1996

Influence of deoxyspergualin on mononuclear phagocytic system in mice.

The influence of deoxyspergualin (DSG) on mononuclear phagocytic system was examined in BALB/c mice. DSG did not influence on both the organ distribution of sheep red blood cells (SRBC) and blood clearance of colloidal carbon when the agent was administered intraperitoneally into mice at doses of 5.0 and 10.0 mg/kg for six consecutive days before antigen. Hemagglutination titers in experimental and control mice did not differ significantly when 10.0 mg/kg of DSG was given six times before SRBC injection. However, when administered during the course of the response (days 0 to 5) DSG (5.0 mg/kg/day) markedly suppressed antibody formation.

Animals↗
PubMed1996

Inhibitory action of deoxyspergualin on effector/memory T cell generation during Hymenolepis nana infection in mice.

The effects of deoxyspergualin (DSG), a newly developed immunosuppressive agent, on protective immunity to Hymenolepis nana reinfection were examined in BALB/c mice. Administration of DSG at daily doses of 10.0 mg/kg to 30.0 mg/kg (but not 5.0 mg/kg) caused suppression of protective immunity when the agent was injected intraperitoneally during the induction phase of the immunity. In contrast, daily administration of 30.0 mg/kg DSG, during effector phase, could not suppress protective immunity. DSG inhibited endogenous interferon-gamma production in mesenteric lymph nodes induced by H. nana challenge infection, when the agent was injected intraperitoneally at a daily dose of 10.0 mg/kg during the induction phase of immunity. Delayed type hypersensitivity (DTH) local transfer analysis revealed that administration of DSG at 10.0 mg/kg/day into donor mice during induction phase of immunity inhibited generation of effector/memory cells that mediate DTH to H. nana egg antigen. However, DSG could not inhibit DTH effector cell activation when cells prepared from H. nana-infected, saline-injected mice were transferred into recipient treated with 10.0 mg/kg DSG. Administration of DSG at a dose of 10.0 mg/kg daily for 5 days produced large DNA fragments in mesenteric lymph node (MLN) cells. These results strongly suggest that DSG suppresses generation of effector/memory cells by apoptotic cell death but cannot suppress lymphocyte activation in vivo.

Animals↗
PubMed1996

Comparison of OspA serotypes for Borrelia burgdorferi sensu lato from Japan, Europe and North America.

UNLABELLED: Sixty-one Borrelia burgdorferi sensu lato strains from various sources (ticks, human, and wild animals) in Japan and two strains from ticks in Far Eastern Russia were classified on the basis of reactivity with 16 monoclonal antibodies (mAb) to outer surface protein A (OspA) and by DNA-DNA hybridization assay. Eleven OspA serotypes (J1 to J11) were recognized among the Japanese and the Far East Russian isolates (serotypes J1 to J9 were identified as B. garinii, serotype J10 was identified as B. afzelii, and serotype J11 corresponded to B. japonica), whereas 7 OspA serotypes for North American and European isolates previously reported (Bettina Wilske et al, J. Clin. Microbiol. 31:340-350,1993) were not observed except for OspA serotype 2 which showed identical reactivity with OspA serotype J10. This finding provides helpful information for understanding the geographical distribution of Lyme disease borrelia and the development of vaccine and diagnostic tests. IN CONCLUSION: 1.B. burgdorferi sensu stricto has not been observed in Japan, 2. Japanese B. afzelii isolates are closely related to those from Europe, 3. B. garinii isolates from Japan are highly heterogeneous and apparently different from European B. garinii isolates.

Animals↗
PubMed1996

[Analysis of verotoxin-producing Escherichia coli (O157:H7) strains isolated in the Fukuoka area in 1994 by pulsed-field gel electrophoresis].

Nine verotoxin-producing Escherichia coli O157:H7 strains were isolated from 9 pediatric patients with sporadic enteritis between July and September 1994 at four clinics in the Fukuoka area. The patients included two families with two cases each. These strains were analyzed by pulsed-field gel electrophoresis for Xba I-digested DNA fragments. The restriction patterns were identical between each two strains within the two family outbreaks, but different among the seven strains of the distinct seven sporadic cases. It is strongly suggested that the seven sporadic cases were infected through distinct sources, and that the two family cases were due to a common source of infection or person to person infection.

Bacterial Toxins↗
PubMed1996

Dipalmitoylphosphatidylcholine liposomes with soybean-derived sterols and cholesterol as a carrier for the oral administration of insulin in rats.

Dipalmitoylphosphatidylcholine (DPPC) liposomes with a soybean-derived sterol mixture (SS) or cholesterol (Ch) were examined as a carrier for the oral administration of insulin in rats. Four kinds of liposomes were prepared: liposomes containing SS or Ch (molar ratio of DPPC/X = 7:2 or 7:4, X = SS or Ch), respectively. The pharmacological availability was greater and the lag time for the glucose reduction was later in the order of DPPC/SS (7:4) > DPPC/SS (7:2) > DPPC/Ch (7:4) > > DPPC/Ch (7:2)-liposomes. This order appears to correspond well with that of the rigidity of the liposomal membrane. In particular, DPPC/SS (7:4)-liposomes reduced blood glucose levels for up to 21 h in rats after oral administration. The highest absolute pharmacological availability was 31.6% at a dose of 20.0 IU/kg of DPPC/SS (7:4)-liposomes among the liposomes in comparison to intravenous administration.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

Nerve-regenerating effect of 15-deoxyspergualin. Peripheral nerve allotransplants in the rat.

We studied the effect of two immunosuppressive agents, 15-deoxyspergualin and cyclosporine A, on various nerve allografts in inbred rats whose major histocompatibility complex was mismatched. As allografts, we used the sciatic nerve (20 mm) and the saphenous nerve (20 mm). We found that 1) fresh peripheral nerve allografts with a short course of 15-deoxyspergualin and cyclosporine A therapy induced more regenerated axons than autografts did, 2) a short course of 15-deoxyspergualin therapy provided better nerve regeneration than cyclosporine A therapy in all forms of nerve allografts and large caliber nerve allografts induced more regenerated axons.

Animals↗
PubMed1995

Distribution of mu-calpain proenzyme in the brain and other neural tissues in the rat.

We raised antibodies against the acetyl N-terminal peptide of the human mu-calpain 80 kDa (80 K) subunit (N-acetyl SEETPVYCT-GVSAQVQKQRARELG) in the rabbit. A specific antibody was purified using N-acetyl SEEITPVYCTGVSAQVQKQ peptide-conjugated Sepharose 4B as an affinity gel support. Epitope analysis revealed that the purified antibody reacted only with mu-calpain N-terminal peptides containing N-acetyl SEETT structure but no reactions occurred with other analogous peptides. Western blot analysis showed that the antibody reacted with both human and rat mu-calpain proenzymes but not with the activated calpains lacking N-terminal peptide. Using this antibody we investigated immunohistochemically the distribution of mu-calpain proenzyme in central and peripheral nervous systems as well as other non-neural tissues in the rat. The proenzyme was detected mainly in neurons both in the central and peripheral nervous tissues, but not in non-neural tissues except for red blood cells. Immunoreaction was stronger in the perikarya and/or in the nuclei than in-the cytoplasm. Specificity of the antibody was verified by an absorption test. In summary, the mu-calpain proenzyme is mainly distributed in the perikarya and/or nuclei or neurons. Our present antibody specific to the N-terminus of the mu-calpain 80 K subunit could serve as a useful tool to detect various functions of mu-calpain as well as the damage in neurons caused by the enzyme.

Amino Acid Sequence↗
PubMed1995

Day-night differences in the contents of vasoactive intestinal peptide, gastrin-releasing peptide and Arg-vasopressin in the suprachiasmatic nucleus of rat pups during postnatal development.

To investigate the developmental features of peptide levels in the suprachiasmatic nucleus (SCN), the contents of vasoactive intestinal polypeptide (VIP), gastrin-releasing peptide (GRP) and Arg-vasopressin (AVP) were measured in punched-out SCN tissue from rat pups on postnatal days (PD) 4, 15 and 20 using a specific enzyme immunoassay. The VIP content was high at night, and the day-night difference was largest at PD4 throughout the developmental stage. GRP and AVP contents increased following the maturation. GRP levels were higher during the dark than the light period from PD4 to PD20. Subjective day-night differences were also observed in blinded pups. Our results indicate that VIP, GRP and AVP in the SCN already show a diurnal rhythm in the SCN during the nursing period.

Age Factors↗
PubMed1995

Appearance of deteriorated neurons on regionally different time tables in rat brain thin slices maintained in physiological condition.

Brain slices are widely used for electrophysiological experiments. However, the time table of the chronological cell deterioration and its regional difference in slices are unknown. The argyrophil III staining method can demonstrate deteriorated ('collapsed') neurons specifically. Therefore we studied the appearance of the 'collapsed' neurons with time in coronal brain 'thin' slices maintained in vitro to evaluate possible regional differences in vulnerability. In the hippocampus, CA1 pyramidal, dentate gyrus granule, and non-pyramidal cells in any subfield became argyrophilic most easily, as did layer V-VI pyramidal neurons in the neocortex. These results suggest that some subclasses of neurons in brain slices degrade earlier than others even when maintained in physiological condition.

Animals↗
PubMed1995

Nerve regenerating effect of short-course administration of cyclosporine after fresh peripheral nerve allotransplantation in the rat: comparison of nerve regeneration using different forms of donor nerve allografts.

There is almost universal agreement that if cyclosporine (CsA), which is a potent immunosuppressant, is temporarily administered after surgery, regenerated axons will be maintained even after withdrawal of CsA following peripheral nerve allotransplantation. Thus, this experimental study was conducted to investigate whether a difference in donor nerve form, including thickness and length, influences nerve regeneration after withdrawal of immunosuppression with CsA. The findings suggest that as a result of immunosuppression with CsA, large-diameter nerve grafts are better able to induce nerve regeneration than small-diameter grafts, and after withdrawal of the immunosuppressant, thick nerve grafts are also better able to preserve regenerated axons against the rejection reaction than thin grafts. With regard to the length of the grafted nerve, short nerve allografts yield higher axon counts than long ones, the same as with autografts. The best way to induce nerve regeneration appears to be to transplant a short, thick nerve allograft, which is definitely capable of inducing many regenerated axons.

Animals↗
PubMed1995

Immunosuppressive effect of 15-deoxyspergualin applied to peripheral nerve allotransplantation in the rat.

15-Deoxyspergualin (15-DSG), which has a unique immunosuppressive action, was applied to peripheral nerve allotransplantation. Its effects on graft survival were experimentally assessed using inbred rats. The sciatic nerve (20 mm) allotransplantation model was created in two different strains. An attempt was made to answer the following two questions: (1) can short-term immunosuppression alone produce sufficient immunological tolerance to maintain graft survival indefinitely? (2) can graft rejection be prevented by chronic intermittent low-dose 15-DSG administration (2.5 mg/kg/day), and to what extent does nerve regeneration occur? To evaluate the efficacy of 15-DSG, a comparison was made with autografts, allografts with no immunosuppression, and allografts immunosuppressed with cyclosporine (CsA), a strong immunosuppressant. The results indicate that short-term 15-DSG therapy is incapable of inducing immunotolerance of peripheral nerve allografts. Because nerve conduction in the rejected allografts was better preserved than in the CsA group, short-course 15-DSG therapy appeared to provide better results than CsA therapy for peripheral nerve allotransplantation.

Animals↗
PubMed1995

The influence of aging on skin temperature and hemodynamic changes during spinal anesthesia.

We investigated the influence of aging on the relationship between arterial pressure and skin temperature as a simple and indirect indicator of cutaneous blood flow. Sole and palm skin temperatures, sublingual temperature, heart rate, mean arterial blood pressure (MAP), and the anesthetic level as determined by cold discrimination, were measured before and during minor surgery under spinal anesthesia in patients under 65 years (young group) and above 65 years (elderly group). The sole skin temperature (Tsole) started to increase in the young group whose anesthesia level reached above L1-L2, and approached the sublingual temperature in those whose anesthesia level reached above T8-T10 after spinal injection. There was, however, no relationship between the anesthesia level and Tsole in the young group. The change in Tsole was less in elderly patients than that in young patients with the same decrease in MAP. These findings suggest that a decrease in peripheral resistance may not be the main cause of hypotension during spinal anesthesia in elderly patients.

Adult↗
PubMed1995

[Isolation of verotoxin-producing Escherichia coli from pediatric patients suffering from enteritis with bloody stool and intussusception].

We tried to isolate verotoxin-producing Escherichia coli (VTEC) on sorbitol-MacConkey (SMAC) agar and in part by the polymerase chain reaction (PCR) method from sporadic enteritis patients with bloody stools and intussusception patients who came to three pediatric clinics in the Fukuoka area from October 1990 to September 1994. VTEC O157:H7 strains were isolated from 6 (10.5%) of 57 patients with bloody stools, Campylobacter spp. 15 (26.3%), Salmonella spp. 14 (24.6%) and Yersinia enterocolitica 2. We were not able to detect VT genes by PCR from 11 of 20 patients from whose stools no causative bacteria were isolated. Massive fresh bloody stools following frequent watery diarrhea were typical of the VTEC enteritis patients. Only 1 patient had fever and 2 had leukocytosis, but the C-reactive protein in all of them was below 1+. The VTEC strains were isolated during the summer season, 1 in June, 2 in July, and 3 in September. Since in the area O157:H7 appeared to be the most prevalent VTEC serotype, SMAC is very useful for screening VTEC in bloody stools. VTEC seems to be a rare pathogen of intussusception because the organisms were detected from none of the 30 patients.

Adolescent↗