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Biomedical subjects

Y Komatsu

Publications and source records attributed to Y Komatsu.

At least 325 records · Page 18Linked to original sources
PubMed1992

Cryoprotection provided by heat shock treatment in Saccharomyces cerevisiae.

Saccharomyces cerevisiae cells exposed to 43 degrees C (normal being 30 degrees C) exhibit the synthesis of heat shock proteins (hsps). Time course studies indicated that the major hsps (97 kDa, 85 kDa and 70 kDa family) are induced within 10 min. of heat shock and attain maximum amount with two hours of treatment. The viability of cells decreased by 99% when directly frozen into liquid nitrogen. However, a prior heat shock (2 hours) increased the cell survival by 20-30 fold. Such an effect of prior heat shock treatment could be supported by light and electron microscopical studies. Differential scanning calorimetric analysis of whole cells revealed that heat shock treatment decreases the denaturation (delta H) of total cellular proteins. A direct correlation between the degree of hsp inducibility and protection against freezing and thawing injury was observed. Cycloheximide treatment curtailed the synthesis of hsps as well as protection against subsequent freezing. This suggests that prior heat shock treatment protects the cells from freezing injury and, furthermore, that hsps can act as biological cryoprotectants.

Calorimetry↗
PubMed1992

[Treatment of metastatic brain tumors: effect of surgery of multiple metastatic brain tumors and systemic metastasis with special reference to quality of life].

To assess the efficacy of surgical resection of brain metastases from patients with multiple brain metastases or/and with other systemic metastases, the authors analysed treatment results of 90 cases of metastatic brain tumors. The patients were divided into three groups. Group A (nine cases): Patients with single brain tumor and their primary cancers were well controlled. Their brain tumors were removed surgically and followed by radiation. Their mean survival time was 17.0 months, and 14.6 months were independent (Karnofsky score greater than or equal to 70) in cases of lung cancer. Five patients (55.6%) improved by treatment. Group B (21 cases): Patients with multiple brain metastases or/and with systemic metastases. Their brain tumor(s) which gave rise to neurological symptoms were surgically removed in order to improve their quality of life. In cases of lung cancer, mean survival time was 9.5 months and 7.1 months were independent. 11 patients (52.3%) improved by treatment. Group C (60 cases): Patients treated conservatively. Their mean survival time was 4.9 months and 2.7 months were independent in cases of lung cancer. Only 13 patients (21.7%) improved by treatment. However 23 (38.3%) deteriorated in their quality of life during treatment. Two patients of this group had single brain tumor and their primary cancers were controlled well. They refused surgery. Their mean survival time was 13.0 months, and 7.0 months were independent. These times were statistically shorter than group A. Seven patients had similar systemic and neurological states as those in group B. Their mean survival time was 5.0 months and 3.0 months were independent. These times were also statistically shorter than those in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Neoplasms↗
PubMed1991

Mutagenesis and self-ligation of the self-cleavage domain of the satellite RNA minus strand of tobacco ringspot virus and its binding to polyamines.

Several mutants for the minus strands of the self-cleaving domain of the satellite RNA of tobacco ringspot virus have been synthesized by joining chemically synthesized oligoribonucleotides with RNA ligase. Kinetic properties of the enzyme strands (50 nucleotides) against substrates (15-mer and 18-mer) were investigated. Structural properties of the unpaired part in the cleavage region were estimated from mutagenesis. The catalytic domain alone was proved to be responsible for the rejoining reaction of cleaved substrates. It was also found that the ribozyme could be divided into two strands without loss of activity. Effects of concentration of magnesium ion and polyamines on the cleavage reaction for the two-stranded ribozyme are also reported.

Base Sequence↗
PubMed1991

Structure/activity relationship of eel calcitonin. A study using a newly devised method for designing analogs.

A series of analogs of eel calcitonin (eCT) was synthesized according to a newly devised scheme, 'the insertion-inactivation method', to clarify the structure/activity relationship of a given peptide. This method consists of two steps: the deletion of a residue of the peptide is first chosen and then a series of analogs with the residue reinserted into serial positions is synthesized and biological activities are assessed in each step. An analog lacking Lys18 (dK), selected as a deleted analog for the first step, showed marked loss of activities determined by inhibition of 125I-eCT binding, growth inhibition, and cAMP production in a porcine kidney cell line LLC-PK1. Activities of a set of 20 analogs with the reinserted lysine residue at serial positions from 12 to 32 (K12-K32) were then evaluated. The results showed the following three patterns of the expression of activities according to the position of the reinsertion: (a) analogs K12-K16 (positions 12-16) and K25 (position 25) showed lower activities than eCT in all assays; (b) K17-K24 (positions 17-24) showed slightly lower activities than eCT in the receptor binding and the growth inhibition and similar level in cAMP production; (c) K26-K32 (positions 26-32) showed considerably lower activities in the former two assays and slightly lower activity in cAMP production. Further, analogs considerably less active than eCT showed unchanged alpha-helix contents and destroyed amphiphilicity by the insertion of a lysine residue, indicating that amphiphilicity is one of important factors for expressing the activity. The results obtained here lead to a conclusion on the significance of each region of eCT molecule as follows: (a) the presence of Lys18 is necessary for the complete expression of biological activity; (b) the length of amphiphilic alpha-helix to be required for the activity is at most 10 residues ranging from position 8 to position 17; (c) the receptor binding region is located within 9 residues ranging from position 24 to position 32.

Amino Acid Sequence↗
PubMed1991

Percutaneous ethanol injection therapy for hepatocellular carcinoma. A histopathologic study.

Histopathologic examination was done on 18 cases after percutaneous ethanol injection therapy (PEIT) for hepatocellular carcinoma. In eight cases, the lesion was treated by PEIT alone; in the other ten cases, PEIT was combined with transcatheter arterial embolization. The lesion was completely necrotic in 13 cases, 90% necrotic in four cases, and 70% necrotic in the rest. In addition, PEIT seemed to be effective against intercapsular, extracapsular, and vascular invasions. In the four cases of incomplete necrosis, the viable cancer tissue remained in small tumor nodules around the main tumor, in portions isolated by septa, or along the edge of the lesion. Therefore, ethanol should be injected not only into the center of the lesion, but also into sites close to its edge. Ethanol did not damage noncancerous liver parenchyma distant from injected sites. Local dissemination of the cancer cells was not found in any case. Therefore, PEIT seems to be a valuable therapy and may be an alternative to surgery in some cases.

Adult↗
PubMed1991

Induction of barotolerance by heat shock treatment in yeast.

In Saccharomyces cerevisiae, heat shock treatment provides protection against subsequent hydrostatic pressure damage. Such an induced hydrostatic pressure resistance (barotolerance) closely resembles the thermotolerance similarly induced by heat shock treatment. The parallel induction of barotolerance and thermotolerance by heat shock suggests that hydrostatic pressure and high temperature effects in yeast may be tightly linked physiologically.

Cycloheximide↗
PubMed1991

Postnatal development of neuronal connections in cat visual cortex studied by intracellular recording in slice preparation.

Postnatal development of neuronal connections in cat visual cortex (area 17) was studied in slice preparations obtained from kittens aged 1-18 weeks after birth and adult cats by recording intracellularly excitatory (EPSP) and inhibitory postsynaptic potentials (IPSP) evoked in cortical cells by stimulation of white matter. The EPSPs were already present in all cells at 1 week of age. Their efficiency assessed by their maximum rate of rise was low initially and increased progressively with age. In contrast, the IPSPs were absent in half of the cells at 1 week and almost all of the cells came to demonstrate inhibition by 9 weeks except for a few layer II-III cells. At all ages about three-quarters of the IPSPs had GABAA-mediated early and GABAB-mediated late components with different time courses, reversal potential and sensitivity to GABA antagonists, while the remaining IPSPs had only the early component. The efficiency of both IPSPs assessed by the associated conductance increase showed an increase of more than twice from 1 to 5 weeks, reaching the same level as adults. The time course of the development of inhibition demonstrated in this study paralleled the time course of the development of selective visual responsiveness in cortical cells, suggesting that the postnatal maturation of inhibitory connections is a basis of maturation of visual responsiveness.

Aging↗
PubMed1991

Multiple-needle insertion method in percutaneous ethanol injection therapy for liver neoplasms.

One of the shortcomings of percutaneous ethanol injection therapy (PEIT) is that many sessions are necessary to accomplish the treatment. In order to reduce the number of treatment sessions, we inserted two or three needles before injection of ethanol was begun. Using the multiple-needle insertion method, we markedly reduced the number of treatment sessions. Histopathologic examination, imaging techniques, and serum alpha-fetoprotein levels showed efficacy of PEIT using the multiple-needle insertion method. No serious complication occurred. Levels of transient pain, fever, and the feeling of intoxication did not seem to be different from those occurring with the conventional method. Multiple-needle insertion method may be valuable as a method for reducing the number of treatment sessions necessary and thus shortening the treatment period.

Carcinoma, Hepatocellular↗
PubMed1991

A case of malignant lymphoma in the liver treated by percutaneous ethanol injection therapy under peritoneoscopic observation.

A 41-year-old woman with non-Hodgkin's lymphoma in the liver was treated with percutaneous ethanol injection therapy. Ethanol injection was performed twice under ultrasonographic guidance for a lesion inside the liver and once under peritoneoscopic observation for lesions on the surface of the liver. CT performed after treatment showed that sizes of the lesions decreased and that the lesions were not enhanced by contrast medium, indicating lack of blood supply and necrosis of the lesion. Ultrasonography performed after treatment did not show any lesions in the liver. There was no sign of recurrence or metastasis.

Adult↗
PubMed1991

In vitro approach to visual cortical development and plasticity.

The neural circuitry in the visual cortex is characterized by two basic types of organization. One is a laminar organization determining the extrinsic and intrinsic neural connections of cortical cells according to their cortical depth, and the other is a columnar organization where cortical cells are arranged perpendicularly according to their response selectivities. It is known that the columnar organization comprises the postnatal structures dependent on the visual experience, while the laminar organization comprises the prenatal structures unmodified by visual experience. We have investigated the interplay between the pre- and postnatal mechanisms using various in vitro preparations, including visual cortical slices, and transplant and co-culture preparations. It was shown in lateral geniculate and visual cortex transplants and co-cultures including the visual cortex lateral geniculate nucleus that all laminar structures are expressed in these preparations according to the prenatal mechanisms. It was also shown in slice preparations that the details of these circuitries are plastic and modifiable by the visual input, although their basic framework is determined prenatally.

Aging↗
PubMed1991

Characterization of mitogenic pectic polysaccharides from kampo (Japanese herbal) medicine "juzen-taiho-to".

The acidic polysaccharide fraction (F-5-2) from "Juzen-Taiho-To" (TJ-48), a Kampo (Japanese herbal) medicine prepared by decocting a prescription of 10 kinds of herbs, has potent mitogenic activity. In order to clarify the mitogenic activity, F-5-2 was fractionated by amon-exchange chromatography, and 14 acidic polysaccharide fractions were obtained. Mitogenic activities of these polysaccharides were increasing with their molecular masses and affinities to the anion-exchange column. Methylation analysis and endo-alpha-(1----4)-polygalacturonase digestion showed these polysaccharide fractions to be pectic polysaccharides, many of which consisted mainly of polygalacturonan regions in addition to small amounts of "ramified" regions. Gel filtration showed that the molecular masses of the "ramified" regions of the polysaccharides were similar. High molecular mass polygalacturonic acid showed a weak mitogenic activity. The mitogenic (M-1 and M-2) and non-mitogenic (M-3) polysaccharides from the most active polysaccharide fraction (F-5-2IIh) were further purified by gel filtration. M-2 and M-3 were also shown to be pectic polysaccharides, and the neutral glycosidic linkages in M-2 and M-3 were different from each other. Endopolygalacturonase digestion markedly decreased the mitogenic activity of M-2, however, the "ramified" region of M-2 still showed a weak activity.

Animals↗
PubMed1991

Potential effects of recombinant human growth hormone (r-hGH) on somatic growth in uremic rats.

In this study, we investigated both the efficacy of growth hormone (GH) in the improvement of growth disturbances in uremia and the effects on the remaining kidney, using uremic rats. Twenty 5/6 nephrectomized uremic rats were divided into two groups. One half of them were injected intraperitoneally with 2IU of human recombinant growth hormone (r-hGH) twice daily. The others were injected only with the vehicle. Sham operated control rats were also injected with the vehicle. These rats were pairfed and observed for as long as 4 weeks, during which, the growth in stature in uremic rats without r-hGH was markedly retarded, with a gain of only 15.8 +/- 3.7 mm of body length. It was significantly less than the 48.0 +/- 5.1 mm (p less than 0.01) gained by control sham-operated rats. By contrast uremic rats treated with r-hGH gained 37.8 +/- 2.9 mm, which was significantly greater than uremic rats without r-hGH (p less than 0.01) but less than controls (p less than 0.01). Increments of body stature paralleled those of skeletal bones. The food utilization rate was significantly improved in uremic rats treated by r-hGH. Throughout the experiment, serum creatinine and urea nitrogen levels remained constant and there were no intergroup differences in the uremic rats including insulin like growth factor I (IGF-1) and other chemical parameters except for plasma GH levels. These results suggest that r-hGH stimulates somatic growth in rats with chronic renal failure through improving food utilization and a probable direct effect on growing cartilage.

Animals↗
PubMed1991

Induction of long-term potentiation without participation of N-methyl-D-aspartate receptors in kitten visual cortex.

1. Intracellular recording was made from layer II-III cells in slice preparations of kitten (30-40 days old) visual cortex. Low-frequency (0.1 Hz) stimulation of white matter (WM) usually evoked an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP). The postsynaptic potentials (PSPs) showed strong dependence on stimulus frequency. Early component of EPSP and IPSP evoked by weak stimulation both decreased monotonically at frequencies greater than 0.5-1 Hz. Strong stimulation similarly depressed the early EPSP at higher frequencies (greater than 2 Hz) and replaced the IPSP with a late EPSP, which had a maximum amplitude in the stimulus frequency range of 2-5 Hz. 2. Very weak WM stimulation sometimes evoked EPSPs in isolation from IPSPs. The falling phase of the EPSP revealed voltage dependence characteristic to the responses mediated by N-methyl-D-aspartate (NMDA) receptors and was depressed by application of an NMDA antagonist DL-2-amino-5-phosphonovalerate (APV), whereas the rising phase of the EPSP was insensitive to APV. 3. The early EPSPs followed by IPSPs were insensitive to APV but were replaced with a slow depolarizing potential by application of a non-NMDA antagonist 6,7-dinitro-quinoxaline-2,3-dione (DNQX), indicating that the early EPSP is mediated by non-NMDA receptors. The slow depolarization was mediated by NMDA receptors because it was depressed by membrane hyperpolarization or addition of APV. 4. The late EPSP evoked by higher-frequency stimulation was abolished by APV, indicating that it is mediated by NMDA receptors, which are located either on the recorded cell or on presynaptic cells to the recorded cells. 5. Long-term potentiation (LTP) of EPSPs was examined in cells perfused with solutions containing 1 microM bicuculline methiodide (BIM), a gamma-aminobutyric acid (GABA) antagonist. WM was stimulated at 2 Hz for 15 min as a conditioning stimulus to induce LTP, and the resultant changes were tested by low-frequency (0.1 Hz) stimulation of WM. 6. LTP of early EPSPs occurred in more than one-half of the cells (8/13) after strong conditioning stimulation. The rising slope of the EPSP was increased 1.6 times on average. 7. To test involvement of NMDA receptors in the induction of LTP in the early EPSP, the effect of conditioning stimulation was studied in a solution containing 100 microM APV, which was sufficient to block completely synaptic transmission mediated by NMDA receptors. LTP occurred in the same frequency and magnitude as in control solution.

2-Amino-5-phosphonovalerate↗
PubMed1991

C-type natriuretic peptide (CNP) in rats and humans.

We have established a specific radioimmunoassay (RIA) for C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, and have elucidated its tissue distribution and molecular form. In rats, high concentrations of CNP-like immunoreactivity (-LI) were detected in the anterior lobe (19.8 +/- 8.6 pmol/g) and neurointermediate lobe (4.64 +/- 0.74 pmol/g) of the pituitary gland. CNP-LI was present throughout the brain with its high concentrations in the hypothalamus and cerebellum. Small amounts of CNP-LI were also detected in the lower part of gastrointestinal tract and the kidney. However, no significant amount of CNP-LI was present in other organs including the heart. Considerable amounts of CNP-LI were detected throughout the human brain. High performance-gel permeation chromatography coupled with the RIA detected two peaks of CNP-LI in the rat brain; CNP and presumably its N-terminally elongated form with 53 amino-acid residues, CNP-53. These findings indicate that the tissue distribution and processing pattern of CNP are clearly different from those of atrial natriuretic peptide and brain natriuretic peptide and suggest possible roles of CNP as a neurotransmitter or neuromodulator rather than as a cardiac hormone.

Animals↗
PubMed1991

Aspergillus mycotic aneurysm--case report.

A 61-year-old female developed subarachnoid hemorrhage after trans-sphenoidal surgery for Rathke's cleft cyst. Neuroradiological examination revealed a large aneurysm at the C1 portion of the right internal carotid artery. Autopsy revealed marked proliferation of aspergillus hyphae in the wall of the aneurysm. A review of previously reported cases of fungal aneurysm proposes two developmental processes. Aneurysms secondary to fungal meningitis tend to be large in size and located in the major cerebral artery trunk, but aneurysms following fungal sepsis tend to be small and in peripheral branches. The former aneurysms are probably caused by fungus invasion into the intracranium, usually from the paranasal sinus, and the latter may be due to fungal emboli like bacterial emboli in bacterial endocarditis. Ruptured fungal aneurysms are difficult to treat, so fungal meningitis or sepsis must be eradicated before an aneurysm develops.

Aneurysm, Infected↗