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Biomedical subjects

K Hara

Publications and source records attributed to K Hara.

At least 1,027 records · Page 57Linked to original sources
PubMed1984

Identification and estimation algorithm for stochastic neural system.

An algorithm for the estimation of stochastic processes in a neural system is presented. This process is defined here as the continuous stochastic process reflecting the dynamics of the neural system which has some inputs and generates output spike trains. The algorithm proposed here is to identify the system parameters and then estimate the stochastic process called neural system process here. These procedures carried out on the basis of the output spike trains which are supposed to be the data observed in the randomly missing way by the threshold time function in the neural system. The algorithm is constructed with the well-known Kalman filters and realizes the estimation of the neural system process by cooperating with the algorithm for the parameter estimation of the threshold time function presented previously (Nakao et al., 1983). The performance of the algorithm is examined by applying it to the various spike trains simulated by some artificial models and also to the neural spike trains recorded in cat's optic tract fibers. The results in these applications are thought to prove the effectiveness of the algorithm proposed here to some extent. Such attempts, we think, will serve to improve the characterizing and modelling techniques of the stochastic neural systems.

Animals↗
PubMed1984

Statistical features of impulse trains in cat's lateral geniculate neurons.

The spontaneous discharges which recorded extracellularly from cells in the lateral geniculate nucleus (LGN) of a cat were classified into the following 3 main groups depending upon the shapes of their interval histograms and autocorrelation functions: the gamma type whose interval histogram is fitted by a gamma distribution function and whose autocorrelation function has some periodic property which damps down within about several 10 ms, the burst type whose interval histogram has a peak in the first bin (less than 8 ms) and whose autocorrelation function has a large positive peak within several msec, and the multimodal type whose interval histogram has a complex shape with three or more peaks and whose autocorrelation function has a periodic property. Each type of spontaneous discharge seems to be inherent at scotopic and mesopic backgrounds, and the cells whose spontaneous discharges are the gamma type, the burst type, and the multimodal type are called here a gamma cell, burst cell, and the multimodal cell, respectively. Gamma cells are subdivided into X- and Y-cells (gamma-X and gamma-Y cells), but burst cells are all Y-cells and multimodal cells observed up to now are all X-cells. It is clear that these various types of cells are distributed significantly differently in each lamina. All the cells that we found up to now in lamina A were either burst cells or multimodal cells, but every type of cell was found in lamina A 1. The majority of cells in lamina C were the gamma type.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Histochemical studies of intercellular components of salivary gland tumors with special reference to glycosaminoglycan, laminin and vascular elements.

In 41 salivary gland tumors, the characteristics of the intercellular components and vascular endothelial cells were surveyed by immunohistochemical staining for laminin and factor VIII-related antigen (VIII R:Ag), and by mucopolysaccharidase-digestion for glycosaminoglycan (GAG). In myxomatous areas of pleomorphic adenomas, small vessels (diameter 6.5 +/- 0.11 micron) were frequent and found to be negative or weakly positive by VIIIR:Ag staining although endothelial cells were clearly positive for VIIIR:Ag in capsule surrounding the tumor tissues. Alcian blue stainability was diminished by treatment with both Streptomyces hyaluronidase and chondroitinase. By laminin staining, a vascular pattern was clearly detected, but the majority of tumor cells were not stained. In adenomatous areas, the basement membrane-like linear laminin-staining reaction was observed to be weak and inconsistent around some tumor cell nests. However, in adenoid cystic carcinomas, laminin-positivity was much more intense than in other tumors such as pleomorphic adenoma, mucoepidermoid tumor and adenocarcinoma. In cylindromatous areas, the inner luminal surface in the pseudocysts was markedly positive for laminin, and there was weak positivity around tumor cell nests having a trabecular pattern. By immunoelectron microscopy, a juxtacellular network of replicated basal lamina of tumor cells which lined the inner surface of pseudocysts was positive for laminin. Alcian blue-positivity in the pseudocyst was abolished with heparitinase and chondroitinase, but not with hyaluronidase.

Adenocarcinoma↗
PubMed1984

A great Brunner's gland adenoma of the duodenal bulb.

The occurrence of Brunner's gland adenoma in the duodenum is infrequent. The authors report a case of great Brunner's gland adenoma of the duodenal bulb, which is of interest because of its great size (8.5 X 4.5 cm) and the negative result of the endoscopic biopsy. Endoscopy has improved the diagnosis of the duodenal tumors; however, traditional endoscopic pinching biopsy does not always make a histological diagnosis. In our case, the endoscopic biopsy was negative because the tumor was located completely in the submucosa and the biopsy forceps was unable to reach to the tumor tissue.

Adenoma↗
PubMed1984

Maternal perception, tocodynamometric findings and real-time ultrasound assessment of total fetal activity.

"Total" fetal motor activity was determined in 111 healthy patients between 25 weeks of pregnancy and term using two real-time ultrasound devices simultaneously. Furthermore tocographic findings and also maternal perception of fetal movements of the same patients were stored synchronously on magnetic tape. A comparison was drawn between these three methods, i.e. real-time ultrasonography, maternal perception and tocographic tracings ("spikes" indicating fetal movements). Of all fetal movements, as assessed by real-time ultrasonography, the mothers perceived a total of 38% whereas "spikes" in tocographic tracings corresponded with fetal motor activity (excluding "breathing") in only 25% of the cases (P less than 0.001). Also major statistically significant differences could be found between maternal perception of fetal body movements with or without fetal limb movements in 56% and routine- tocography in 37% (P less than 0.001). Also isolated limb movements were most often detected by mothers (23%) than were revealed by tocographic findings (14%; P less than 0.001). Maternal signals were truly positive in 74% compared to tocography in only 56% of the cases (P less than 0.001). It is concluded that maternal perception of fetal movements is a more reliable method of monitoring fetal motor activity than analysis of tocographic tracings.

Adolescent↗
PubMed1984

Development of human fetal muscles: a comparative histochemical analysis of the psoas and the quadriceps muscles.

The development of human muscle can be divided into three distinct phases on the basis of the enzyme histochemistry (Dubowitz 1965). On the other hand, muscles can be classified into trunk muscles innervated by the motoneurons in the anteromedial nucleus of the anterior horn and limb muscles innervated by those of the lateral nucleus. We compared histochemically the development of the psoas muscle as a trunk muscle with the quadriceps. Four legally aborted fetuses and sixteen autopsied preterm or full-term infants with conceptional ages ranging from sixteen to fourty-two weeks, served as subjects. Serial crossly cut frozen sections of the psoas and the quadriceps were stained with HE, modified Gomori-trichrome, NADH-TR, myofibrillar ATPase (routine, preincubation at pH 4.6, 4.3), and analyzed quantitatively. In the psoas and the quadriceps, all muscles consisted of undifferentiated type IIC fibers before the eighteenth week of gestation. Type I fiber began to appear around the eighteenth week in both muscles. Before the thirtieth week, both muscles comprised a great number of smaller type IIC fibers and scattered large type I fibers. The psoas had already a little more type I fibers than the quadriceps in this phase. After the thirtieth week, the percentage of type I fibers increased greatly to about 50% at term in the psoas, gradually to 20-23% at term in the quadriceps. Type IIA and IIB fibers appeared suddenly around the thirty-seventh week. Total percentage of these two type fibers increased at term to about 50% and 70% in the psoas and the quadriceps, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1984

Purification and characterization of cathepsin B from monkey skeletal muscle.

Cathepsin B was purified about 11,000-fold from monkey skeletal muscle by ammonium sulfate fractionation and sequential column chromatographies monitored by assaying of Z-Phe-Arg-MCA hydrolase activity. The purified enzyme gave a single protein band on SDS-polyacrylamide gel electrophoresis, and its molecular weight was estimated to be 24,000 by gel filtration. It had a pH optimum of 6.5, required a thiol reducing agent for activation, and was inhibited by various thiol protease inhibitors. These properties were similar to those reported for cathepsins B from other sources. Although the enzyme scarcely hydrolyzed ordinary proteins, such as casein, hemoglobin, and bovine serum albumin, it degraded myosin and actin among various myofibrillar proteins. These results strongly suggested that skeletal muscle cathepsin B may participate in the degradation of muscle proteins in vivo. In addition, cathepsin B was shown to hydrolyze various neuropeptides such as Leu-enkephalin, beta-neoendorphin, alpha-neoendorphin, dynorphin(1-13), and substance P. It appeared to act on these peptides mainly as a dipeptidyl carboxypeptidase, although not so rigorously, presumably due to its endopeptidase activity.

Animals↗
PubMed1984

Neurophysiological evaluation of newborns with congenital hydrocephalus.

EEGs and visual and auditory evoked potentials (VEP and AEP) were studied in 27 newborns with congenital hydrocephalus. Asynchronous sleep patterns were the main EEG abnormality in the newborn as well as in the older infants and children. Asynchronous tracé alternant patterns, the most common finding, were more frequently encountered in infants with more severe hydrocephalus. Asynchrony of bifrontal humps was another finding observed in a few infants. Intermittent semirhythmic theta or delta waves were noted in some infants. Depression of the EEG background activity was an infrequent finding observed in more severe hydrocephalus. VEP showed prolonged latency in 60% of cases, but its wave form was normal in most cases, even sometimes in patients with highly abnormal EEGs. Therefore, it can serve as a tool to assess the maturity of such infants. In contrast, AEP was normal in 76% of the cases. The neonatal EEG findings were significantly correlated with the clinical outcome and can be an additional prognostic indicator in congenital hydrocephalus.

Arnold-Chiari Malformation↗
PubMed1984

Determination of free tryptophan in plasma and its clinical applications.

Free tryptophan in plasma was separated by centrifugation through an Amicon ultrafiltration membrane cone. The value obtained without control of pH was found to be lower than that obtained with control of pH by an improved method ( Hijikata et al. (1981) Anal. Biochem. 118, 10-16). For determination of the total tryptophan concentration in the plasma, high performance liquid chromatography (HPLC) was better than the method of Denckla Dewey as modified by Bloxam & Warren ( (1974) Anal. Biochem. 60, 621-625), as judged on the basis of sensitivity, recovery rate and coefficient of variance. The total tryptophan concentration in the plasma determined by HPLC was lower than that determined by the Bloxam & Warren method. The total tryptophan concentration (t-Trp), free tryptophan concentration (f-Trp) and f-Trp/t-Trp ratio were 55.8 +/- 10.2 mumol/l, 11.6 +/- 1.5 mumol/l and 0.211 +/- 0.03 (mean +/- 1 SD) respectively, in healthy subjects (controls). No significant difference was observed between the values of controls and those of patients with liver cirrhosis, hepatocellular carcinoma, liver cirrhosis with hepatocellular carcinoma and hepatic encephalopathy of liver cirrhosis without bleeding. But in liver cirrhosis with bleeding, free tryptophan concentration (f-Trp, 48.0 +/- 23.3 mumol/l, p less than 0.001) and f-Trp/t-Trp ratio (0.645 +/- 0.289, p less than 0.001) were significantly higher than those of controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1984

Maternal perception of fetal movements and real-time ultrasound findings.

Two real-time ultrasound instruments were used simultaneously for comprehensive recording of "total" fetal motor activity in 50 patients in the second half of pregnancy. Synchronously, cardiotocographic findings and maternal perception of fetal movements were stored on magnetic tape. In most cases fetal "gross" movements were perceived by the mothers (mean: 63%). Isolated movements of fetal extremities were reported by the mother in only about 15% of all cases. Mothers registered a total of all movements in 37%. We found a statistically significant difference in the percentage of perceived fetal movements with regard to parity (p less than 0.001) and with regard to gestational age (p less than 0.01). With multiparity or an increasing gestational age the body movements of the fetuses were felt more accurately by the mothers. In 30% of all cases the mothers perceived movements without sonographic confirmation. The findings of this study suggest that maternal perception of major fetal body movements is accurate in the majority of cases. However, the relatively high rate of false positive maternal perception should be taken into consideration if the maternal record of daily fetal movements is to be used for fetal monitoring.

Female↗