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Biomedical subjects

K Negishi

Publications and source records attributed to K Negishi.

At least 145 records · Page 8Linked to original sources
PubMed1988

Effects of cyclosporin A and insulin on peripheral lymphocytes in BB/W rats.

The effects of cyclosporin A (Cs-A) and insulin on peripheral lymphocytes in BB/W rats were studied. The cumulative incidence of overt diabetes in untreated BB/W rats was 72% up to 120 days of observation, whereas the incidence was 13% in Cs-A-treated rats. Lymphocytopenia, consisting of decreased OX19+ (pan T), W3/25+ (helper/inducer T) and OX8+ (cytotoxic/suppressor T) cells, was present in BB/W rats. Cs-A significantly decreased both the percentage and the absolute number of OX8+, OX6+ (Ia-positive) and OX12+ (B) cells, and augmented the ratio of W3/25+ to OX8+ cells in BB/W rats. On the other hand, insulin injection significantly decreased the percentage of OX6+ cells and the ratio of W3/25+ to OX8+ cells in BB/W rats. Thus, rearrangement of the ratio of helper/inducer T to cytotoxic/suppressor T cells and reduction in the number of Ia antigen-bearing cells could be important for the inhibitory effects of diabetes in BB/W rats upon treatment with Cs-A or insulin.

Animals↗
PubMed1988

A sensitive radioimmunoassay for circulating alpha-interferon in the plasma of healthy children and patients with measles virus infection.

The mean circulating alpha-interferon of healthy children aged 2 to 13.5 yrs as measured by a radioimmunoassay was 0.119 +/- 0.031 ng/ml, which was significantly lower than that of young adults. Circulating alpha-interferon of children with measles virus infection aged 1 to 11 yrs, on their first visit to the hospital when they were fully symptomatic, was 0.095 +/- 0.035 ng/ml (n = 39). It was 0.105 +/- 0.070 ng/ml (n = 21) on their second visit, 7 to 10 days after their first visit when the patients were convalescent. The difference was statistically insignificant. It is concluded that immunoreactive circulating alpha-interferon is low in children and reaches maximum level in young adults, subsequently declining gradually with age. Immunoreactive circulating alpha-interferon, a possible reflection of endogenous alpha-interferon, does not change significantly by the infection of measles virus.

Acute Disease↗
PubMed1988

Interferon responsiveness of natural killer cells in type I human diabetes.

Abnormally low circulating numbers and function of NK cells are associated with new onset type I diabetes. Since alpha interferon is a stimulator of NK function, enriched T and non-T lymphocytes were incubated with 0, 100 and 1,000 units/ml of recombinant alpha interferon (rIFN alpha) and natural killing against K562 and pancreatic islet cell targets was measured. The killing of K562 (1:20 target:effector ratio) cells by non-T cells incubated with 0, 100 and 1,000 units/ml of rIFN alpha in patients was decreased to 27% (p less than 0.014 vs control), 34% (p less than 0.001) and 39% (p less than 0.003) when compared to killing by normal control non-T cells (48%, 74% and 58% respectively). T cell mediated killing of K562 cells in patients was decreased to 3.9% (p less than 0.03), 5.3% and 6.6% (p less than 0.003) when compared to that of controls (8.7%, 10-8% and 22.6% respectively). Non-T cell mediated killing of islet cells (1:20 target:effector ratio) following treatment of effector cells with 0, 100 and 1,000 units/ml of rIFN alpha in patients was 19%, 27%, and 26% which was comparable to control subjects killing of 31%, 18% and 37% respectively. Similar data were obtained using T-cells as effectors. These data indicate that in new onset type I diabetes; (a) NK cell functional activity is diminished in both T and non-T lymphocyte subpopulations and (b) NK activity is suboptimally enhanced with rIFN alpha.

Adolescent↗
PubMed1988

[Two autopsy cases of primary pituitary carcinoma].

We studied two autopsy cases of primary pituitary carcinoma. Case-1. A 45 year old female was admitted on Oct. 4 1978, with a complaint of right homonymous hemianopsia. And diagnosis was pituitary adenoma. Partial removal of pituitary tumor was performed on Oct. 23 1978. She died on Dec. 5 1978 due to bleeding of gastrointestinal tract. Autopsy disclosed a pituitary carcinoma invading the left hypothalamus, mamillary body, optic and V cranial nerves, and mid brain as well as sphenoid bone. No extracranial metastasis was noted. Case-2. A 44 year old female with a history of acromegaly for 6 years was admitted with a complaint of headache on May 8 1976. She was diagnosed as having pituitary adenoma. The subtotal removal of pituitary tumor was performed on May 21 1976 and followed by 4500 rad irradiation. At this time, pathological diagnosis was eosinophilic adenoma. Seven years later, she complained of progressive right hearing disturbance, dysarthria and ataxic gait 1983. The second subtotal removal of pituitary tumor was performed with a diagnosis of recurrence of pituitary adenoma on Oct. 7 1983. After the operation, she complicated sepsis and died on Jan. 14 1984. An autopsy disclosed a pituitary carcinoma from residual pituitary gland, continuously extending to the subarachnoid space of the pons, and invading right cerebello-pontine angle and cerebellum. The histological examination revealed pituitary carcinoma with high pleomorphism and glioblastoma multiform-like feature were within the tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1987

Proofreading of a mutagenic nucleotide, N4-aminodeoxycytidylic acid, by Escherichia coli DNA polymerase I.

N4-Aminodeoxycytidine triphosphate, a putative metabolite of N4-aminocytidine which is a potent mutagen, is incorporated, in vitro, into polynucleotides in place of dCTP and at a much lesser extent, but significantly, in place of dTTP by E. coli DNA polymerase I large fragment. The activity of the polymerase to proofread this unnatural nucleotide has now been investigated. The results indicate that the 3'-5' exonuclease in the polymerase recognizes N4-aminocytosine as an incorrect base when N4-aminocytosine is incorporated opposite adenine but the enzyme cannot distinguish N4-aminocytosine from cytosine when it is incorporated opposite guanine.

DNA Polymerase I↗
PubMed1987

Mutagenicity of N4-aminocytidine and its derivatives in Chinese hamster lung V79 cells. Incorporation of N4-aminocytosine into cellular DNA.

N4-Aminocytidine induced mutation to 6-thioguanine resistance in Chinese hamster lung V79 cells in culture. Previous studies with experimental systems of in vitro DNA synthesis and of phage and bacterial mutagenesis have shown that this nucleoside analog induces base-pair transitions through its incorporation into DNA, with its erroneous base-pairing property. Incorporation of exogenously added [5-3H]N4-aminocytidine into the DNA of V79 cells was in fact observed in the present study. N4-Aminodeoxycytidine was not mutagenic for the V79 cells. Several alkylated N4-aminocytidine derivatives were tested for their mutagenicity in this system. Those with an alkyl group on the N'-nitrogen of the hydrazino group at position 4 of N4-aminocytidine were mutagenic, but those having an alkyl on the N4-nitrogen were not. These results are consistent with those previously observed in the bacterial mutagenesis systems, and agree with a mechanism of mutation in which a tautomerization of N4-aminocytosine is the necessary step for causing the erroneous base pairing.

Animals↗
PubMed1987

Two types of lamprey retina photoreceptors immunoreactive to rod- or cone-specific antibodies.

The localization of structures immunoreactive to antisera against opsin (OPS; a specific marker for rods) and against visinin (VIS; a specific marker for cones in the vertebrate retina) was investigated in the retina of the river lamprey (Lampetra japonica) by means of fluorescence microscopy. Different immunoreactive structures were found with the two antisera. A vitreadly located structure in the outer nuclear layer displayed OPS-like immunoreactivity, while a scleradly located one exhibited VIS-like reactivity. Thus, the two antisera applied to the retina of the river lamprey permit the distinguishing of rod and cone immunoreactive photoreceptors such as occurs typically in all vertebrate classes. The former appears in the outer segments of a type of rod cells, and the latter in the cell bodies and axons of cones.

Animals↗
PubMed1987

Paradoxical induction of dopaminergic cells following intravitreal injection of high doses of 6-hydroxydopamine in juvenile carp retina.

Histofluorescence studies were conducted on two groups of juvenile carp (body length, 12.7 and 6.6 cm on the average, respectively) during certain periods (3-11 months) of retinal growth, to evaluate the destructive effect of 6-hydroxydopamine on dopaminergic and indoleamine-accumulating cells. Within a certain range of doses (0.1-5.0 micrograms/eye) of the neurotoxin injected intravitreally, it was found to destroy both classes of cells in a dose-dependent manner: more cells disappeared with higher doses. However, a high dose (5-25 micrograms/eye) of the neurotoxin caused paradoxical events in the retina, inducing an appearance of clustered dopaminergic cells with various soma sizes and abnormally high regional density, disturbed laminar organization, and a facilitated growth rate at the retinal margin. A preliminary examination with [3H]thymidine labelling suggests that the high dose of 6-hydroxydopamine may cause severe damage to certain classes of cells including dopaminergic and indoleamine-accumulating cells, and that a metamorphic change of precursor cells (neuroblasts) in the outer nuclear layer is responsible for the induction of such abnormal dopaminergic cells as clusters.

Age Factors↗
PubMed1987

Dendritic morphology of indoleamine cells revealed by intracellular injection of lucifer yellow in fixed carp retina.

The dendritic morphology of indoleamine amacrine cells in carp retina was investigated by identifying their fluorescent cell bodies by preloading with noradrenaline followed by iontophoretic injection of Lucifer Yellow in isolated and aldehyde-fixed preparations under microscopic control. Although two subpopulations of serotonin-like immunoreactive amacrine cells (small and large in soma size) were found, small cells were not seen in aldehyde-fixed preparations. Cells preloaded with noradrenaline corresponded to large immunoreactive cells and were labeled with Lucifer Yellow. The cell bodies labeled were located at the innermost level of the inner nuclear layer, and gave rise to three to five primary dendrites which branched frequently and were found mainly in sublamina a of the inner plexiform layer. These cells examined in an intermediate region between the optic disc and the retinal periphery were pyriform in soma shape while dendritic fields were found or oval covering an area of 0.18 +/- 0.05 mm2 (510 +/- 80 microns in diameter). Cell density in this region was about 32 cells/mm2 and, therefore, their dendritic field coverage was approximately 6.0.

Animals↗
PubMed1987

Functional and morphological correlates of amacrine cells in carp retina.

Experiments were conducted on isolated retinas of adult carp (Cyprinus carpio) to investigate correlations between photoresponses and morphological features of amacrine cells. The fluorescence dye Lucifer Yellow CH was iontophoretically injected into single cells which had been characterized electrophysiologically. Photoresponses were classified into two main types (transient ON-OFF and sustained), which were further subgrouped into "fast" and "slow" ON-OFF types and into ON-center and OFF-center types, respectively. In the spectral response curve, all the types dealt with showed a maximum response at 621 nm, indicating that main input signals derive from red-sensitive cones. The cells marked by intracellular injection of the dye showed a great variety in morphology. Cells were classified into 8 subtypes, based on soma shape (fusiform or pyriform), dendritic field area (narrow, less than 0.3 mm2; medium, 0.3-0.8 mm2; wide, greater than 0.8 mm2), and dendritic stratification in the inner plexiform layer (restricted to sublamina a or b, or distributed diffusely). In certain cases a given response type was correlated with a specific morphological type, while receptive field size was not strictly correlated with dendritic field areas. Long and fine peripheral "axon-like" processes were found to arise from the primary dendrites of most fusiform cells. Dye-coupling was found among cells which appear to belong to the same cell category.

Action Potentials↗
PubMed1987

Natural killer cell and islet killer cell activities in human type 1 diabetes.

Peripheral blood mononuclear cells from 14 type 1 diabetic patients were examined for natural killer cell activity using the K562 cell line as 51Cr labeled targets. Mean cytotoxicity of K562 cells by unseparated mononuclear cells derived from new onset type 1 patients (12 +/- 1.6%) was lower (P less than .01) than that observed in non diabetic controls, (25 +/- 4.2%). Mean natural killer cell cytotoxicity mediated by enriched non-T cells from patients (41 +/- 5.8%) was also lower (P less than 0.03) than in the control group (56 +/- 3.7%). Specificity of these findings was evaluated by also examining other diabetic patient subgroups. Mean non T cell mediated natural killer cell activity in type 2 diabetic patients and type 1 patients with long term disease was 65 +/- 5.4% and 62 +/- 4.8% respectively (p less than 0.001 vs new onset type 1 patients). Longitudinal studies of new onset type 1 patients during the remission (honeymoon) phase revealed no improvement of impaired natural killer cell activity. In 30 new onset and 11 remission diabetic patients, mean non-T cell-mediated cytotoxicity was also measured using dispersed 51Cr labeled pancreatic islet target cells. Mean islet cytotoxicity mediated by cells from new onset patients was 34 +/- 2.4%, whereas in nondiabetic control subjects mean cytotoxicity was 25 +/- 1.8% (p less than 0.005). During remission, islet cytotoxicity returned to normal values in over half of the patients. There was no correlation between K562 and islet cell cytotoxicity in either of the latter two patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Studies of midaglizole (DG-5128). A new type of oral hypoglycemic drug in healthy subjects.

Midaglizole (DG-5128), 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylethyl]pyridine dihydrochloride sesquihydrate, is a novel alpha 2-adrenoceptor antagonist. Its effects on plasma glucose, immunoreactive insulin (IRI), and immunoreactive glucagon (IRG) in healthy male volunteers were investigated. Volunteers received single oral administrations of midaglizole (150-500 mg), multiple increasing oral administration on 3 separate days (150-300 mg 3 times daily), or successive daily oral administration for 1 wk (200 mg 3 times daily). The hypoglycemic action of midaglizole was observed within 0.5-1.0 h after its administration and thereafter for 5 h. The maximum hypoglycemic effect was found 1.0-1.5 h after administration. Midaglizole decreased postprandial hyperglycemia in a dose-dependent manner. In the fasting state, midaglizole significantly increased IRI secretion and suppressed IRG secretion. Midaglizole inhibited epinephrine-induced platelet aggregation after successive administration for 1 wk (200 mg 3 times daily). The plasma half-life of midaglizole was only 3 h, and the drug was rapidly excreted into the urine and feces, with greater than 80% in its unchanged form, within 24 h. Midaglizole did not affect the results of any clinical or laboratory tests performed. Our data indicate that midaglizole is a possible hypoglycemic agent. Further clinical investigations are required to confirm its effects on diabetes mellitus.

Administration, Oral↗
PubMed1987

Initial phase II clinical studies on midaglizole (DG-5128). A new hypoglycemic agent.

Midaglizole (DG-5128), 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylethyl]pyridine dihydrochloride sesquihydrate, is a new type of oral antidiabetic agent that has an alpha 2-adrenoceptor-antagonizing effect. As previously reported, midaglizole reduces plasma glucose, mainly by stimulation of insulin secretion, and inhibits epinephrine-induced platelet aggregation in normal human subjects. In this study, the clinical safety and efficacy of short-term administration of midaglizole were evaluated in 47 patients with non-insulin-dependent diabetes mellitus (NIDDM). After an observation period on diet or sulfonylurea treatment (1 patient was on insulin), patients received 150-250 mg 3 times a day of midaglizole for 2-4 wk, (some patients continued treatment for greater than 4 wk). In 20 of the patients first treated with diet and then switched to midaglizole treatment, fasting plasma glucose (FPG) decreased significantly from 187 +/- 10 mg/dl (mean +/- SE) to 147 +/- 13 mg/dl (P less than .05) and 120 +/- 6 mg/dl (P less than .01) 2 and 4 wk, respectively, after administration of midaglizole. Glycosylated hemoglobin (HbA1) also decreased from 12.0 +/- 0.7 to 11.3 +/- 1.1 and 10.7 +/- 0.6% after 2 and 4 wk, respectively. In 23 of the patients whose treatment was changed from sulfonylureas to midaglizole, FPG, and HbA1 levels were maintained at the same values obtained before administration of midaglizole. In patients treated with midaglizole for greater than 12 wk, FPG and HbA1 were kept at the lowered levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1986

Cross-linking between 16S ribosomal RNA and protein S4 in Escherichia coli ribosomal 30S subunits effected by treatment with bisulfite/hydrazine and bromopyruvate.

Cytosine in nucleic acids can be modified by treatment with a mixture of bisulfite and hydrazine. The reaction is specific for single-stranded regions of nucleic acids and the product is N4-aminocytosine. Bromopyruvate has been used for alkylation of protein SH groups and through its 2-oxo group it can form a hydrazone with N4-aminocytosine. Escherichia coli ribosomal 30S subunits were treated with 1 M sodium bisulfite + 2 M hydrazine in the presence of 10 mM MgCl2 at pH 7.0 and 37 degrees C for 30 min. By this treatment, 2.4 cytosine residues/molecule 16S rRNA were derivatized into N4-aminocytosines. 35S-labeled 30S subunits were modified in this way and then treated with 10 mM bromopyruvate at pH 8.0 and 37 degrees C for 5 min. Analysis in sodium dodecyl sulfate/sucrose density gradient centrifugation showed co-sedimentation of a part of the 35S radioactivity with the RNA. The co-sedimentation was dependent on both the bisulfite/hydrazine and the bromopyruvate treatments. The RNA-protein complex was prepared from unlabeled 30S subunits. The protein portion was labeled with 125I, the RNA portion was digested with nucleases, and then the hydrazone linkage between the protein and oligonucleotides was cleaved by treatment with 0.2 M HCl. The oligonucleotides formed were removed by dialysis and the protein was identified as S4 by two-dimensional electrophoresis and by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The results indicate that the cysteinyl residue of protein S4 at position 31 from the N-terminus is located close to a cytosine residue which is non-base-paired and easily accessible by the externally present bisulfite/hydrazine reagent.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

Dendritic morphology of dopaminergic cells revealed by intracellular injection of Lucifer yellow in fixed carp retina.

The dendritic morphology of dopaminergic cells in carp retinas was investigated by identifying their fluorescent cell bodies in isolated, aldehyde-fixed preparations and injecting them iontophoretically with Lucifer yellow CH (LY) under microscopic control. The LY-injected cells were examined in flatmount and in radial cryosections. The cell bodies were located at the inner margin of the inner nuclear layer (the amacrine cell sublayer), and gave rise to 3-5 primary dendrites that branched repeatedly within the inner plexiform layer to form a narrow-field, diffusely branched dendritic tree. In some cases, a distal process was found to extent to the outer plexiform layer, representing the interplexiform type of cells. The 59 filled cells had roughly round or oval dendritic fields covering an area of 0.102 +/- 0.003 mm2 (361 +/- 57 micron in diameter) in the intermediate retinal region. The density of dopaminergic cells in this region was 31 cells/mm2 and, therefore, the dendritic field coverage of these cells approximately 3.0.

Animals↗
PubMed1986

An immunohistochemical study on the river lamprey retina.

The localization of structures immunoreactive to various polypeptides and proteins in the retina of the river lamprey (Lampetra japonica) was investigated by means of an indirect immunohistofluorescence method. In the majority of frozen sections, a subpopulation of amacrine cells showed the immunoreactivity (IR) to one of the examined antisera against corticotropin-releasing factor, glucagon, neuropeptide Y, somatostatin, visinin and 5-hydroxytryptamine, respectively. A few fibers in the inner plexiform layer were immunoreactive to cholecystokinin or substance P antiserum. The visinin-like IR was also found in two types of bipolar cells. The IR was positive in Müller cells against glutamine synthetase but not to glial fibrillary acidic protein. In some flat-mounted preparations, glucagon- and serotonin-like reactive amacrine cells and visinin-like immunoreactive bipolar cells (distally located) could be observed. The results obtained suggest that in the lamprey retina the cytoplasmic property of some cells is similar to, but that of others is different from, vertebrate retinal cells.

Animals↗
PubMed1986

Natural killer cell and islet killer cell activities in type 1 (insulin-dependent) diabetes.

Peripheral blood mononuclear cells from 20 Type 1 (insulin-dependent) diabetic patients were examined for natural killer cell activity using the K562 cell line as 51Cr labeled targets. Mean natural killer cell cytotoxicity mediated by enriched non-T cells from patients (37 +/- 4.0%) was lower (p less than 0.03) than in controls (56 +/- 3.7%). Specificity was evaluated by examining other patient subgroups. Mean non-T cell mediated natural killer cell activity in Type 2 (non-insulin-dependent) diabetic patients and Type 1 patients with long term disease was 65 +/- 5.4% and 62 +/- 4.8% respectively (p less than 0.003 vs new onset Type 1 patients). Longitudinal studies of new onset Type 1 patients during the remission (honeymoon) phase revealed persistently impaired natural killer cell activity in 3 of 4 patients. In 30 new onset and 11 remission Type 1 diabetic patients, mean non-T cell-mediated cytotoxicity was also measured using dispersed 51Cr labeled islet target cells. Mean islet cytotoxicity mediated by cells from new onset patients was 34 +/- 2.4%, whereas in non-diabetic control subjects mean cytotoxicity was 25 +/- 1.8% (p less than 0.005). During remission, islet cytotoxicity remained at similar or elevated levels in most patients. In patients evaluated simultaneously for K562 and islet cell cytotoxicity, natural killer cell activity was decreased, whereas islet killing was increased. These results suggest a dichotomy in natural killer cell and islet killer cell activities in new onset Type 1 diabetes that could have an important role in the pathogenesis of Type diabetes.

Adolescent↗