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Biomedical subjects

S Katayama

Publications and source records attributed to S Katayama.

At least 217 records · Page 12Linked to original sources
PubMed1995

The enterotoxin gene (cpe) of Clostridium perfringens can be chromosomal or plasmid-borne.

The location of the cpe gene, encoding the enterotoxin responsible for food poisoning in humans, has been studied in a series of enterotoxigenic Clostridium perfringens strains by means of pulsed field gel electrophoresis of genomic DNA. The cpe gene was found at the same chromosomal locus in strains associated with food poisoning in humans and was shown to be linked to a repetitive sequence, the HindIII repeat, and an open reading frame, ORF3, that may be part of an insertion sequence. In contrast, when the strains originated from domesticated livestock cpe was located on a large episome where it was often close to a copy of the transposable element IS1151. In these cases, the HindIII repeat was not linked to the cpe gene although this was generally preceded by ORF3.

Blotting, Southern↗
PubMed1995

Rapid expansion of the physical and genetic map of the chromosome of Clostridium perfringens CPN50.

The physical map of the 3.6-megabase chromosome of Clostridium perfringens CPN50 was extended by positioning sites for the endonucleases SfiI and I-CeuI, and in parallel, the gene map was expanded by using a genome scanning strategy. This involved the cloning and sequencing of random chromosomal fragments, identification of the functions of the putative genes by database searches, and then hybridization analysis. The current gene map comprises almost 100 markers, many of which encode housekeeping functions while others are involved in sporulation or pathogenesis. Strikingly, most of the virulence genes were found to be confined to a 1,200-kb segment of the chromosome near oriC, while the pleiotropic regulatory locus, virRS, was situated toward the putative replication terminus. A comparison of the gene maps of three endospore-forming bacilli, C. perfringens, Clostridium beijerinckii, and Bacillus subtilis, revealed a similar order and distribution of key sporulation and heat shock genes which might reflect an ancient evolutionary relationship.

Chromosome Mapping↗
PubMed1995

Phylogenetic analysis of phospholipase C genes from Clostridium perfringens types A to E and Clostridium novyi.

The phylogenetic interrelationships between strains of 5 toxin types (A to E) of Clostridium perfringens were examined by analysis of differences in the nucleotide sequences of phospholipase C genes (plc genes) among 10 strains, including 3 strains for which the plc gene sequences have been previously reported. A plc gene was also cloned from a Clostridium novyi type A strain and sequenced to analyze the interspecies diversity of plc genes. Phylogenetic trees constructed by the neighbor-joining method revealed that the phylogeny of C. perfringens strains is not related to toxin typing, in agreement with the results of a comparative genome mapping study by Canard et al. (B. Canard, B. Saint-Joanis, and S. T. Cole, Mol. Microbiol. 6:1421-1429, 1992). Various C. perfringens phospholipase C enzymes were purified from cultures of Escherichia coli cells into which the encoding plc genes had been cloned. All of the enzymes showed the same specific activity. On the other hand, the level of plc transcripts differed greatly (up to 40-fold) from one C. perfringens strain to another. No significant difference in the nucleotide sequence of the plc promoter region was observed for any of the plc genes. These results suggest that the variation in phospholipase C activity among different strains is not due to mutation in the plc coding region but to that in an extragenic region. The evolution of C. perfringens phospholipase C is discussed on the basis of similarities and differences between clostridial plc genes.

Amino Acid Sequence↗
PubMed1995

Protective effect of the combined vaccine prepared from cell-free-antigen of Actinobacillus pleuropneumoniae serotypes 1, 2 and 5 in pigs.

Cell-free-antigens prepared from a concentrated culture supernatant of Actinobacillus pleuropneumoniae (A. pleuropneumoniae) serotypes 1, 2 and 5 were mixed and emulsified with oil adjuvant. The combined vaccine of these 3 serotypes of A. pleuropneumoniae was tested for its ability to confer protection. Pigs immunized with the combined vaccine survived and showed no clinical signs against an intratracheal challenge with A. pleuropneumoniae. In contrast, control pigs inoculated with concentrated culture media emulsified with oil adjuvant developed typical symptoms of pleuropneumonia after challenge inoculation.

Actinobacillus Infections↗
PubMed1995

Protective efficacy of cell-free-antigen of Actinobacillus pleuropneumoniae in mice.

Cell-free-antigen (CFA) vaccines of strain Y-1 (serotype 1), G-4 (serotype 2) and E-3 (serotype 5) of Actinobacillus pleuropneumoniae (A. pleuropneumoniae) were prepared by emulsifying concentrated culture supernatant with oil-adjuvant. Mice immunized with the CFA vaccine had a high survival rate (90-100%) against challenge with the homologous strain. They also had cross-protective activity against challenge with the heterogeneous strains but their survival rate was low (20-50%). On the other hand, mice immunized with whole cell vaccine showed serotype specific protection and only a little cross protection. The protective antigens of the CFA were investigated. MAbs were produced by the standard method using spleen cells of mice immunized with CFA. MAbs to Apx I, II, III and capsular antigen of serotype 5 were obtained. Only MAbs to Apx I showed hemolysin neutralization activity among them. The protective effect of these MAbs against A. pleuropneumoniae infection were examined by passive immunization. Administration of Apx I MAb to mice extended survival time after challenge with serotype 5. The mice showed partial cross-protection against challenge with serotype 1. Survival rate was considerably low after the challenge infection. None of the mice given MAbs to Apx II or III were protected against challenge with serotype 5. The mice given MAb to capsular antigen of serotype 5 had a high survival rate (70%) against a challenge with a homologous serotype. Furthermore, mice given MAbs against Apx I and capsular antigen of serotype 5 were completely protected against a challenge with A. pleuropneumoniae serotype 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinobacillus Infections↗
PubMed1995

Choroid plexus carcinoma in the lateral ventricle--case report.

A 68-year-old male presented with choroid plexus carcinoma in the left lateral ventricle manifesting as dysarthria and gait disturbance. Magnetic resonance imaging showed a homogeneously enhanced mass in the trigone of the left lateral ventricle. Selective left posterior cerebral arteriography showed the tumor was fed by the left medial posterior choroidal artery. Detailed examinations found no evidence of an extraneural primary focus. He underwent partial removal of the tumor followed by local Lineac irradiation (50 Gy). After irradiation, the serum level of carcinoembryonic antigen decreased and the size of the residual tumor was reduced.

Adenocarcinoma↗
PubMed1995

Cerebral gumma showing linear dural enhancement on magnetic resonance imaging--Case report.

A 51-year-old male presented with a rare cerebral gumma accompanied by abducens nerve paresis and cerebellar infarction. Magnetic resonance (MR) imaging demonstrated a homogeneous enhance mass lesion and adjacent linearly enhanced dura mater. Histological examination of the mass revealed a caseating granuloma. Serological studies were positive for active syphilis. Although linear dural enhancement adjacent to the mass lesion on MR imaging is characteristic of meningioma, this finding is also demonstrated in cerebral gumma. Therefore, cerebral gummas should also be included in the differential diagnosis. Immunological tests for syphilis (serum, cerebrospinal fluid) can confirm the diagnosis.

Abducens Nerve↗
PubMed1995

Treatment of cystic lesions of soft tissue using fibrin sealant.

A new method was devised for treating 29 patients with cystic lesions of the soft tissue (popliteal cysts, bursitis, and ganglia) by injecting a fibrin sealant into the cyst after the aspiration of the contents. During the followup period (mean, 2.2 years), cysts did not recur in 22 (76%) patients. Of the 7 patients with recurrences, 4 were treated again in the same manner and 3 of these cases have not recurred. Additionally, to investigate the healing process in cysts, fibrin sealant was injected into the space between the abdominal muscle and the peritoneum of rats. Specimens were obtained after the rats were sacrificed at 1, 2, 4, and 8 weeks after injection, and were examined histopathologically. The fibrin sealant was found to be completely resorbed and replaced with organized granulation tissue. In case of multiple failed aspirations to the cystic lesions, this new method is recommended before surgery.

Adolescent↗
PubMed1995

[An operative case of the dumbbell type retromediastinal schwannoma].

Neurogenic tumors of the mediastinum with an intraspinal component connected by a narrowed segment in the intervertebral one are generally described as dumbbell or hour-glass tumors, which need cautious and precise diagnoses and remedies, compared with other neurological tumors. A 62-year-old male was admitted to our hospital for abnormal tumor shadow in the chest X-ray film. We diagnosed this case as dumbbell type neurogenic tumor by MRI and CT. An operation was performed by modified Grillo's method: One-stage operation. With patient in prone position, L-shaped skin incision was made. Through total laminectomy of T-5 and T-6 and resection of the 6th rib, paravertebral portion of the tumor was removed, and thoracotomy in the same position under the same view enabled us to remove the residual tumor. Histopathological diagnosis was schwannoma. After the operation, no neurological complications were detected.

Humans↗
PubMed1995

[Amygdaloid kindling in variously aged infant rats and rekindling after maturation: epileptogenesis and its persistence].

To study amygdaloid kindling in variously aged infant rats and rekindling development after their maturation, 34 male Wistar rats were subjected to initial kindling 13 days after birth (13-day-old group, 9 rats), 16 days after birth (16-day-old group, 9 rats), 18 days after birth (18-day-old group, 7 rats), or 26 days after birth (26-day-old group, 9 rats). Each group received reoperation on the 70th day, and was subjected to rekindling 5 days after operation. Also, a control group of mature rats was initially kindled at the age of 75 days and rekindled after 2 months (75-day-old group, 11 rats). The obtained results are summarized as follows. I. Results of initial kindling: (1) a significant positive correlation was found between the age of the 4 groups of rats and the after-discharge threshold of infant rats (p < 0.05), (2) significant correlations were not found between the age of the 4 groups of infant rats and the stimulation numbers inducing C0-2 and C0-4 stage symptoms, (3) a significant positive correlation was found between the age of the 4 groups of infant rats and the stimulation number inducing C3-4 symptoms (p < 0.05). II. Results of rekindling: (1) significant negative correlations were found between the age of the 4 groups at initial kindling and the stimulation numbers inducing C0-2, C3-4 and C0-4 symptoms (p < 0.05-0.0001). III. Ratio of initial kindling and rekindling: (1) significant negative correlations were found between the age at initial kindling and the C0-2 and C0-4 stimulation number ratios (p < 0.00001), (2) a negative but not significant correlation was found between the C3-4 stimulation number ratio and age at initial kindling. These results suggest that in infant rats amygdaloid excitability is stronger, when the younger the rat, and that the later in the infant period the epileptogenesis is acquired, the stronger is it preserved even after maturation as high amygdaloid excitability.

Aging↗
PubMed1995

[Vasomotor impairment in patients with diabetic neuropathy--evaluation by laser Doppler flowmetry].

Using laser Doppler flowmetry, we evaluated cutaneous microcirculation in 28 patients with diabetic neuropathy and 18 control subjects. Skin blood flow in the hand was significantly reduced in the patients compared with that in age-matched controls. Skin blood flow in the hand of the patients correlated significantly with the amplitude of sensory nerve action potential of the median nerve. Significant correlation was shown in the patients between skin blood flow in the hand and changes in systolic blood pressure on standing from a supine position. However, there was no correlation between skin blood flow in the hand and variation in the R-R interval. These results suggest that the skin blood flow may decrease with the progression of diabetic neuropathy, particularly sympathetic autonomic neuropathy, and that neural control may be an important factor in the regulation of skin blood flow. Cold water immersion test revealed that there was no significant difference in vasoconstrictive response during the cold challenge, while recovery time of vasodilatory response after withdrawal of the thermal challenge was significantly prolonged in the patients as compared with that in the controls. In addition, it is suggested that the patients with a small increase or normal in skin blood flow of the hand may possess abnormalities predominantly in vasoconstrictive tone, whereas the patients with a decrease in skin blood flow of the hand in vasodilatory tone. Consequently, microcirculation in skin of extremities changes under the balance of vasoconstrictive and vasodilatory tones in patients with diabetic neuropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetic Neuropathies↗
PubMed1994

Reciprocal changes in left ventricular collagen alpha 1 chain gene expression between types I and IV in spontaneously diabetic rats.

The characteristic features of diabetic cardiomyopathy have been reported to be increased collagen formation associated with impairment of ventricular performance, based on experimental models of diabetes. The present study was therefore designed to clarify collagen gene expression in hearts obtained from female spontaneously diabetic BioBreeding Worcester Tokyo (BB/W@Tky) rats. Cardiac hypertrophy was observed as early as 14 weeks in diabetic BB/W@Tky rats, i.e. 4 weeks after the onset of diabetes. Left ventricular gene expression of collagen alpha 1 (I) was decreased to 10.6% of the control level. In 24-week-old diabetic rats, which had more marked cardiac hypertrophy, the level of alpha 1 Type I collagen mRNA was further decreased to 5.7% of the control level, whereas collagen alpha 1 (IV) mRNA demonstrated a 3-fold increase. As a result, a ratio of collagen alpha 1 (IV) to actin mRNA was positively correlated with plasma glucose concentration. These results suggest that hyperglycemia may alter the gene expression of extracellular matrix proteins, resulting in the morphological and functional changes seen in diabetic cardiomyopathy.

Actins↗
PubMed1994

Calcium-activated neutral proteinase (calpain) system in aging and Alzheimer's disease.

Calpains (CANPs) are a family of calcium-dependent cysteine proteases under complex cellular regulation. By making selective limited proteolytic cleavages, they activate or alter the regulation of certain enzymes, including key protein kinases and phosphatases, and induce specific cytoskeletal rearrangements, accounting for their suspected involvement in intracellular signaling, vesicular trafficking, and structural stabilization. Calpain activity has been implicated in various aging phenomena, including cataract formation and erythrocyte senescence. Abnormal activation of the large stores of latent calpain in neurons induces cell injury and is believed to underlie neurodegeneration in excitotoxicity, Wallerian degeneration, and certain other neuropathologic states involving abnormal calcium influx. In Alzheimer's disease, we found the ratio of activated calpain I to its latent precursor isoform in neocortex to be threefold higher than that in normal individuals and those with Huntington's or Parkinson's disease. Immunoreactivity toward calpastatin, the endogenous inhibitor of calpain, was also markedly reduced in layers II-V of the neocortex in Alzheimer's disease. The excessive calpain system activation suggested by these findings represents a potential molecular basis for synaptic loss and neuronal cell death in the brain in Alzheimer's disease given the known destructive actions of calpain I and its preferential neuronal and synaptic localization. In surviving cells, persistent calpain activation may also contribute to neurofibrillary pathology and abnormal amyloid precursor protein trafficking/processing through its known actions on protein kinases and the membrane skeleton. The degree of abnormal calpain activation in the brain in Alzheimer's disease strongly correlated with the extent of decline in levels of secreted amyloid precursor protein in brain. Cytoskeletal proteins that are normally good calpain substrates become relatively calpain resistant when they are hyperphosphorylated, which may contribute to their accumulation in neurofibrillary tangles. As a major effector of calcium signals, calpain activity may mirror disturbances in calcium homeostasis and mediate important pathologic consequences of such disturbances.

Aging↗
PubMed1994

Newly identified genes involved in the signal transduction of Escherichia coli K-12.

We cloned and sequenced two Escherichia coli genes which are members of a family of an environmentally responsive two-component system. The nucleotide (nt) and deduced amino-acid sequences of these two genes were found to be homologous to those of the Bordetella pertussis bvgA and bvgS genes. They were mapped at 51 min (clones 6B9 to 7G9 of the Kohara miniset library of the E. coli chromosome). Both proteins, deduced from their nt sequences, were identified in the coupled in vitro transcription-translation system; their molecular masses were consistent with BvgA and BvgS (23 and 135 kDa, respectively). Furthermore, when these genes were expressed on a multicopy plasmid in an envZ deletion strain, ompC expression was induced. This expression was found to be regulated by low temperature, MgSO4 and nicotinic acid, factors known to control the virulence of B. pertussis via BvgA and BvgS. These results indicate that the newly cloned genes were structurally and functionally similar to bvgA and bvgS, and we designated these genes evgA and evgS.

Amino Acid Sequence↗
PubMed1994

Assessment of the pathological grade of astrocytic gliomas using an MRI score.

To evaluate the usefulness of an MRI score for identifying tumour tissue characteristics, 41 histologically verified supratentorial astrocytic gliomas, including 13 low-grade astrocytomas (LGA) 14 anaplastic astrocytomas (AA) and 14 glioblastoma multiformes (GBM), were examined with a 0.5T superconductive MR imager. Nine MRI criteria were used: heterogeneity (HET), cyst formation or necrosis (CN), haemorrhage (HEM), crossing the midline (CM), oedema or mass effect (EM), border definition (BD), flow void (FV), degree (CE-D) and heterogeneity (CE-HET) of contrast enhancement; Gd-enhanced T1-weighted images were obtained in 32 cases (10 LGA, 10 AA, and 12 GBM). Each of the criteria was scored and analysed statistically. The mean values of LGA, AA and GBM were 0.45 +/- 0.31, 1.18 +/- 0.20, and 1.47 +/- 0.22, respectively. The MRI score increased with the pathological grades (P < 0.01-0.001). LGA had significantly lower values than AA in five (HET, CN, EM, BD, CE-D) of the nine criteria (55.6%) and lower values than GBM in all except HEM (88.9%). Three criteria (33.3%): HET, CN, and FV were significantly higher in GBM than AA. CE-D, HET, EM, CN, and CE-HET proved to be related to the pathological grade by a multiple regression analysis (P < 0.001).

Adolescent↗
PubMed1994

Improvement of glucose tolerance by bezafibrate in non-obese patients with hyperlipidemia and impaired glucose tolerance.

Glucose intolerance or diabetes mellitus, hyperlipidemia, obesity and hypertension may have a close interrelation based on insulin resistance. We selected 28 impaired glucose tolerance (IGT) patients with hyperlipidemia. The IGT patients demonstrated hypertriglyceridemia associated with hyperinsulinemia, a typical manifestation of insulin resistance. Administration of bezafibrate at 400 mg/day for 4 weeks to the IGT patients with hypertriglyceridemia resulted in an improvement of the plasma glucose level and insulin response to 75 g oral glucose loading associated with a concomitant decrease in non-esterified fatty acids. The ratio of the level of serum C-peptide to that of insulin after a 75 g oral glucose tolerance test (OGTT) was augmented after 4 weeks of bezafibrate administration. However, reduction of the cholesterol level with pravastatin did not alter these parameters. These results suggest that treatment to reduce the level of serum triglycerides, but not that of cholesterol, may have a beneficial effect for improving insulin resistance even in the non-obese subjects with IGT and decreasing the risk of coronary heart disease.

Bezafibrate↗
PubMed1994

Cortical control of saccade in normal and schizophrenic subjects: a PET study using a task-evoked rCBF paradigm.

In this study, positron emission tomography (PET) was used to evaluate cortical control of saccades. Regional cerebral blood flow (rCBF) patterns demonstrated by 15O water PET during saccadic task performance were tested in 13 normal volunteers and 20 ICD-9 schizo phrenics (10 unmedicated and 10 medicated). The following 3 saccadic tasks, which were controlled for sensory input and oculomotor output, were applied: (1) reflexive saccade = visually guided saccade, (2) volitional saccade = visually guided saccade with distracting stimuli, and (3) memory guided saccade. Schizophrenics lacked the frontal eye field (FEF) activation during every saccadic task. The left dorsolateral prefrontal cortex (DLPFC) was activated during volitional saccade only in normal controls. The rCBF of posterior parietal cortex increased in parallel with that in the DLPFC. These findings suggest functional hypofrontality in schizophrenia and the left DLPFC-PPC's crucial role in saccade against distracting stimuli and its dysfunction in the disease.

Adolescent↗