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Biomedical subjects

K Suda

Publications and source records attributed to K Suda.

At least 307 records · Page 17Linked to original sources
PubMed1983

5-methyltetrahydrofolate-related enzymes and DNA polymerase alpha in normal and malignant hematopoietic cells.

The activities of 5-methyltetrahydrofolate (5-CH3-THF)-related enzymes [5-CH3-THF homocysteine methyltransferase and 5,10-methylenetetrahydrofolate (5,10-CH2-THF) reductase] and DNA polymerase alpha were measured in normal and malignant hematopoietic cells. The 5-CH3-THF homocysteine methyltransferase activity was significantly correlated with 5,10-CH2-THF reductase activity, indicating that the hematopoietic cells with active biosynthesis of tetrahydrofolate from 5-CH3-THF also actively synthesize 5-CH3-THF from 5,10-CH2-THF. The activities of 5-CH3-THF-related enzymes had a tendency to be high in lymphoid cells and low in myeloid cells, and were not correlated with the percentage of blasts and immature cells in the samples examined. Fairly good correlations were observed among these three enzymes in non-malignant bone marrow cells. However, the activities of two of the enzymes correlated only weakly overall with DNA polymerase alpha activity in normal and malignant hematopoietic cells. Generally speaking, DNA polymerase alpha activity correlated well with the percentage of blasts and immature cells in the samples examined.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed1983

Intra-arterial ACNU therapy for malignant brain tumors. Experimental studies and preliminary clinical results.

The authors examined the growth rate of mouse 203 glioma cells in vitro and found it to be markedly inhibited after exposure to ACNU for 5 minutes at a drug concentration of 100 micrograms/ml. Rats that had undergone intracranial implantation of T1 neurogenic tumor were treated by 5 mg/kg of ACNU administered either intravenously or intra-arterially. The median survival times for the control animals and the animals undergoing intravenous or intracarotid administration of ACNU were 23, 29, and 46 days, respectively. The difference in survival time between the intravenous and intracarotid administration groups was statistically significant (p less than 0.01) when examined by the Cox-Mantel test. In a clinical trial, 17 patients with glioblastoma were treated by ACNU, eight intravenously and nine by the intra-arterial route. The drug was given in doses of 2 to 3 mg/kg at least twice before and twice after a course of postoperative radiotherapy. Intra-arterial administration was performed over a period of 5 minutes under local anesthesia. The median postoperative survival time for the patients in the intra-arterial group was 12.5 months, compared with 9.0 months for those in the intravenous group. The survival rate for the intra-arterial group was slightly higher, although statistically not significant, probably because the number of cases was small. The degree of thrombocytopenia due to ACNU tended to be less marked in the intra-arterially treated patients. The theoretical advantages of the intra-arterial administration of ACNU are discussed.

Adult↗
PubMed1983

A histopathological study on the etiology of duodenal diverticulum related to the fusion of the pancreatic anlage.

In 18 of 27 cases a duodenal diverticulum, which usually occurs at "weak" spots in the bowel wall, penetrated the pancreas. Of these, 14 cases (77.8%) extended along the embryological fusion line of the ventral and dorsal components, which is considered to be the so-called "locus minoris resistantiae." In four cases the diverticulum penetrating the ventral pancreas was in close approximation to the locus minoris resistantiae.

Aged↗
PubMed1983

Effects of nitrous oxide on human cell lines.

Hematopoietic and nonhematopoietic cell lines cultured in media containing either 5-methyltetrahydrofolate or 5-formyltetrahydrofolate grow well to the same extent. However, when these same cell lines are grown in the presence of nitrous oxide, selective growth inhibition can be shown for hematopoietic cells cultured in 5-methyltetrahydrofolate-containing media. These cells also demonstrated a decreased ability to suppress [3H]-thymidine incorporation into DNA in deoxyuridine suppression tests.

B-Lymphocytes↗
PubMed1982

Effects of stimulation of the dorsocaudal claustrum on activities of striate cortex neurons in the cat.

In the cat striate cortex, single electrical shocks applied to the dorsocaudal claustrum (CLdc) elicited bimodal excitatory responses with about 12 and 26 ms latencies. About one-fourth of the cortical cells observed had CLdc-induced inhibitions with onset latencies longer than the excitations. On cortical field responses to geniculate stimulation, CLdc conditioning shocks exerted early facilitatory and late inhibitory effects which were shown to be not transmitted through the mesencephalic reticular formation.

Animals↗
PubMed1982

Laminar differences in development of afferent innervation to striate cortex neurones in kittens.

We studied 587 cells in the striate cortex of 47 kittens, ranging in age postnatally from the 8th day to the 20th week, to explore differences in rates of functional maturation of cells and afferents among cortical layers. For all cells studied we determined spontaneous activity level, visual responsiveness, responsiveness to electrical stimulation of the afferent pathways and histologically reconstructed their laminar localization. At the 2nd-3rd week postnatally, single shocks applied to the dorsal lateral geniculate nucleus (LGN) elicited relatively inconsistent responses with long latencies in most of the cells in all layers, except in layer V where responses were consistent. In layers IVab, V, and VIu (the upper half of layer VI) the LGN-latency decreased very rapidly in the 4th week, while in layer IVc such a decrease occurred in the 5th week. In layers II+III and VIl (the lower half of layer VI) a less substantial decrease in latency occurred during the 4th and 5th week. At 2 weeks, nearly half of layer V cells had orientation-specific visual responses or spontaneous activity, but such cells were rare in other layers. The proportions of the specific or spontaneously active cells matured successively in the order of layers V leads to IVab and VIu leads to IVc leads to II+III and VIl. We conclude that the maturation of functional properties of cortical cells may occur successively in the above-mentioned laminar order, and that cells size and connectivity with afferents may be factors influencing the rate of functional maturation of cortical cells. The intracortical synaptic delay was estimated for each of the cells driven mono-synaptically from the LGN. The average delay decreased most rapidly during the 4th and 5th week. Conduction velocities of afferents innervating the mono-synaptic cells in layers IVab and IVc were calculated. The velocity of the former afferents increased very quickly and reached a value suggesting myelination at 4 weeks, while that of the latter afferents at 5 weeks. Since each type of LGN cell is known to project separately to layers IVab and IVc, respectively, this suggests that Y-cells of LGN may mature earlier than X-cells.

Aging↗
PubMed1982

Postnatal development of the corticofugal projection from striate cortex to lateral geniculate nucleus in kittens.

In kittens ranging in age from the eighth postnatal day to twentieth week, 288 striate cortex cells were identified as projecting to the dorsal lateral geniculate nucleus (LGN) on the basis of antidromic activation from LGN and of histological localization of cortical layer VI. These cells (C-G cells) were classified as complex, simple, or visually unresponsive, as in the adult. During the second-third postnatal weeks, most of the C-G cells were visually unresponsive. They often showed a marked step in the negative stroke of spikes evoked by single shock stimulation. When paired shocks with short intervals were applied, the second spike fractionated at the step to reveal the A and B components. This tendency was not observed at 8-9 weeks or later. At the second week, all the visually responsive cells were complex, while simple cells were recorded at 3 weeks or later. Until the fourth week, LGN-latencies of complex cells were very long (11-35 ms), although they were the shortest group at each age. Adult-like latencies were first observed at the fifth week in complex cells and at the eighth-ninth weeks in simple cells. The axonal conduction velocities of complex cells attained to the values suggesting myelination at the fifth week, while those of simple cells much later. These results suggest that complex C-G cells may mature prior to simple cells. By comparison with previous results it is also suggested that myelination of the retino-geniculo-cortico-geniculate projections may occur in a retinofugal order.

Aging↗
PubMed1982

Subpopulation of T cells sensitive to natural thymocytotoxic autoantibody (NTA) of New Zealand mice. I. Distinct cytotoxic sensitivity of functional T cell subsets to NTA and anti-thy-1 antibodies.

NZB mice produce a natural thymocytotoxic autoantibody (NTA) capable of specifically injuring thymocytes and T cells. NTA-reactive antigen (NTA-A) shows a different density distribution among T cells, and partial killing with NTA and complement can eliminate T cells bearing NTA-A in high density. Thy-1 antigen is similar to NTA-A in this respect. To determine the effects of NTA and anti-Thy-1 on distinct functional subsets of T cells, Con A-induced suppressor T cell (Con A-Ts) activity against the allogeneic mixed lymphocyte reaction (MLR), responding T cell (TMLR) activity in the allogeneic MLR, and Con A-induced cytotoxic T cell (Con A-Tc) activity were examined simultaneously in BALB/c spleen cells before and after partial elimination of NTA- and anti-Thy-1-sensitive T cells. Treatment with NTA and complement resulted in a marked reduction in Con A-Ts activity, a significant increase in TMLR-activity and a slight and inconstant decrease in Con A-Tc activity. Since Con A-generated T's were much less sensitive to NTA, the NTA-sensitive T cells involved in Con A-Ts activity appear to be precursors or promoters of the Con A-Ts. In contrast, the precursors of Con A-Tc seem to relatively resistant to NTA. The increase in TMLR activity caused by NTA suggests the possibility that NTA is less cytotoxic for TMLR and cytotoxic for some suppressor T cells in allogeneic MLR. The monoclonal anti-Thy-1 antibody showed no such preferential cytotoxic effects on the three T cell functions. The NTA-sensitive T cells, in contrast to anti-Thy-1-sensitive T cells, were reduced gradually during Con A stimulation. All these findings indicate that NTA-A not only differs from Thy-1 antigen but that it appears to be a unique T cell antigen.

Animals↗