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Biomedical subjects

H Mikawa

Publications and source records attributed to H Mikawa.

At least 127 records · Page 7Linked to original sources
PubMed1990

The syndrome of Möbius sequence, peripheral neuropathy, and hypogonadotropic hypogonadism.

We report on a 17-year-old Japanese boy with Möbius sequence, peripheral neuropathy, and hypogonadotropic hypogonadism, the fourth such case known to us. The association of peripheral neuropathy and hypogonadotropic hypogonadism in Möbius sequence seems to be more than coincidence. Pulsatile gonadotropin-releasing hormone administration for 3 months showed the effectiveness of this treatment for this patient.

Adolescent↗
PubMed1990

Metabolic basis for differential glutamine requirements of human leukemia cell lines.

We compared the ability of human leukemia cell lines of various origins to grow in glutamine-deficient media. The growth of B lymphoblastoid cell lines, including promyelocytic HL-60, is highly dependent on glutamine, whereas T-cell lines are able to proliferate in glutamine-free media. Such glutamine dependency has a good inverse correlation with the activity of glutamine synthetase. Moreover, glutamine synthetase can be induced in glutamine-deficient media, especially in glutamine-independent cells. In HL-60 cells, glutamine deprivation results in the decrease of both ATP and dATP levels. The addition of adenine to the culture medium abolishes these changes without restoring cell growth, indicating that the effects of glutamine deprivation on cell growth cannot be fully explained by the perturbation of adenine nucleotide pools.

Adenine↗
PubMed1990

Decreased benzodiazepine receptor binding in epileptic El mice: a quantitative autoradiographic study.

Benzodiazepine receptors and subtypes were examined in El mice and normal ddY mice with a quantitative autoradiographic technique. Specific [3H]flunitrazepam binding in stimulated El mice, which had experienced repeated convulsions, was significantly lower in the cortex and hippocampus than in ddY mice and unstimulated El mice. In the amygdala, specific [3H]flunitrazepam binding in stimulated El mice was lower than in ddY mice. There was a tendency for the [3H]flunitrazepam binding in these regions in unstimulated El mice to be intermediate between that in stimulated El mice and that in ddY mice, but there was no significant difference between unstimulated El mice and ddY mice. [3H]Flunitrazepam binding displaced by CL218,872 was significantly lower in the cortex of stimulated El mice than in that of the other two groups, and in the hippocampus of stimulated than of unstimulated El mice. These data suggest that the decrease in [3H]flunitrazepam binding in stimulated El mice may be due mainly to that of type 1 receptor and may be the result of repeated convulsions.

Animals↗
PubMed1990

GABA-gated chloride ion influx in brains of epileptic El mice.

GABA-gated chloride ion influx was measured in brain "microsac" preparations of epileptic El mice. There was significantly greater sensitivity to GABA in stimulated El mice (which had 14-18 convulsions induced at weekly intervals) than in unstimulated El mice (which had not experienced convulsions) or ddY mice. GABA-gated chloride ion influx was significantly decreased 20 min after a single convulsion, and returned to the preconvulsion level 60 min after a convulsion. These findings suggest that the functional state of GABA-gated chloride channel in El mice is changed secondarily by single or repeated convulsions.

Animals↗
PubMed1990

Agranulocytosis following infectious mononucleosis.

A girl developed acute agranulocytosis (45/mm3), 37 days after the onset of infectious mononucleosis. The bone marrow showed myeloid hyperplasia with maturation arrest and erythroid hypoplasia. A normal amount of colony forming units of granulocytes and macrophages (CFU-GM) colonies with a relative high number of clusters was observed. Neither anti-neutrophil antibodies nor circulating inhibitors of colony growth were found in serum. Granulocyte and macrophage colony stimulating factor (GM-CSF) activity in the patient's serum rose at this time. The agranulocytosis lasted 5 days and her clinical state soon improved. These results suggested that agranulocytosis was presumably not due to serum factors, including auto-antibodies and/or suppressive substances, and that Epstein-Barr virus (EBV) had some direct or indirect effect on the marrow cells of the myeloid series.

Agranulocytosis↗
PubMed1990

Biochemical basis of the prevention of 6-thiopurine toxicity by the nucleobases, hypoxanthine and adenine.

Co-incubation of human leukemia cell lines with naturally occurring nucleobases (hypoxanthine or adenine) significantly prevented the cytotoxic activity of 6-thiopurines. Extracellular hypoxanthine decreased the transport of 6-mercaptopurine into cells, but adenine had no significant effect. However, intracellular thioinosine monophosphate accumulation in the presence of 10 microM, 6-mercaptopurine was reduced to below 1% or 10% of that of the controls when 50 microM hypoxanthine or adenine was added, respectively. Finally, in adenine phosphoribosyl transferase deficient mutants, adenine provided no protective effect against 6-thiopurines, whereas hypoxanthine retained its modulating activity. These data suggest that the nucleobases compete with 6-thiopurines for the ribose-phosphate donor, 5'-phosphoribosyl-1-pyrophosphate, thus preventing the formation of active metabolites of 6-thiopurines.

2-Aminopurine↗
PubMed1990

Cell type dependent activation of poly (ADP-ribose) synthesis following treatment with etoposide.

Treatment of human non-lymphoid cell lines, HL-60 and U937, with etoposide stimulated poly (ADP-ribose) synthesis three- to fourfold, whereas no significant effects were observed in the lymphoid cell lines, Molt4 and CEM. This was confirmed by either an increased uptake of radio-labelled NAD into the acid-insoluble fraction or a fall in cellular NAD levels, which was counteracted by 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase. On the other hand, another DNA damaging agent, N-methyl-N'-nitro-N-nitrosoguanidine augmented poly(ADP-ribose) synthesis equally in both cell types. These results taken together indicate that the activation of poly(ADP-ribose) synthesis following exposure to etoposide is a cell type specific phenomenon.

Cell Survival↗
PubMed1990

Co-transfer of restriction endonucleases and plasmid DNA into mammalian cells by electroporation: effects on stable transformation.

We co-transferred cloned HSV thymidine kinase gene and restriction endonucleases, HindIII, XbaI, or XhoI, into thymidine kinase-deficient mouse LtK- cells by electroporation. Stimulation of the transformation efficiency was observed with HindIII or XbaI, while little effect was observed with XhoI. The stimulation was observed for various forms of exogenous DNA (linear or circular plasmid DNA and single-stranded phage DNA) and correlated with the number of strand breaks in the host-cell DNA. These results suggest that the presence of DNA double-strand breaks stimulates the integration of exogenous DNA into host cell genomes.

Animals↗
PubMed1990

NMDA-sensitive L-[3H]glutamate binding in cerebral cortex of El mice.

NMDA-sensitive L-[3H]glutamate binding was examined in the brains of El mice, a genetic animal model of epilepsy, and in ddY mice. In whole brain, Scatchard analysis showed that both stimulated and unstimulated El mice had significantly lower Bmax values for binding than did ddY mice. In regional studies, the binding of NMDA-sensitive L-[3H]glutamate was significantly less in the cerebral cortex of both stimulated and unstimulated El mice than in that of ddY mice. These data suggest that NMDA receptors may be involved in the genetic susceptibility of El mice to seizures.

Animals↗
PubMed1990

Complex I (reduced nicotinamide-adenine dinucleotide-coenzyme Q reductase) deficiency in two patients with probable Leigh syndrome.

Two infants who had clinical and radiographic findings consistent with Leigh syndrome were found to have deficiency of complex I (reduced nicotinamide-adenine dinucleotide--coenzyme Q reductase) activity. Significant abnormalities were found on computed tomographic scans and magnetic resonance images of the brain. Lactate and pyruvate concentrations in blood and cerebrospinal fluid were elevated, and muscle biopsy specimens showed abnormal mitochondria. These data indicate that Leigh syndrome, as well as MELAS syndrome (mitochondrial encephalopathy, myopathy, lactic acidosis, and stroke-like episodes) may result from complex I deficiency.

Brain Diseases, Metabolic↗
PubMed1990

Epileptic seizures difficult to differentiate from alternating hemiplegia in infants: a case report.

A child with epileptic seizures had a clinical course similar to that of alternating hemiplegia of infancy (AHI). Tonic hemiplegia began at 2 months of age, and atonic alternating hemiplegia and tetraplegic attacks began at 2 years of age. Clinical findings were paroxysmal ocular movement abnormalities, choreoathetotic involuntary movements, and severe developmental retardation. An interictal EEG at 6 years of age showed multiple independent spike discharges. An ictal EEG showed diffuse irregular spike-wave and slow wave bursts following focal spikes. The present case suggests that a long-term extensive follow-up is necessary to differentiate epileptic seizures from AHI.

Child↗
PubMed1990

Magnetic resonance imaging in relation to EEG epileptic foci in tuberous sclerosis.

In 20 patients with tuberous sclerosis (TS), who were sequentially treated for epilepsy at our clinic, the high signal lesions in the cerebral cortex and subcortex detected on T2 weighted magnetic resonance imaging (MRI) were compared with the interictal EEG findings. In four cases who showed a unilateral distribution of the MRI lesions, there was a good correlation between the laterality of the affected lobes and the localization of the EEG epileptic foci. Thirteen cases with more than four affected lobes in both hemispheres also showed bilateral epileptic foci on EEG. The MRI lesions in the occipital lobes showed the best correlation with the EEG epileptic foci, while the worst correlation was seen in the frontal lobes. In addition, the cases with four or more affected lobes without laterality on MRI are more likely to show bilateral synchronization on EEG. The prognosis of epilepsy in these cases was found to be rather poor.

Adolescent↗
PubMed1990

Metabolism and toxicity of electroporated 1-beta-D-arabinofuranosylcytosine triphosphate in a human leukemia cell line.

The metabolism and toxicity of 1-beta-D-arabinofuranosylcytosine triphosphate (ara-CTP) directly injected into cells by electroporation was studied in human leukemia cell lines. The intracellular accumulation of ara-CTP (ara-CTP-Ep) was dependent on the cell type, extracellular ara-CTP concentration and pulse voltage on electroporation. In a promyelocytic leukemia cell line, HL-60, ara-CTP-Ep revealed a cytotoxic effect in a dose-dependent manner, although electroporation alone did not have any significant toxicity. Furthermore, simultaneous injection of dCTP, or continuous exposure to deoxycytidine, but not to other deoxyribonucleosides, immediately after electroporation rescued the cells from the toxicity of ara-CTP-Ep. The degradation of ara-CTP-Ep consisted of an early rapid phase followed by a slower phase with a half life of 1.5 h. The addition of dipyridamole (10 microM), an inhibitor of nucleoside transport, retarded this degradation process. These data indicate that transfer of ara-CTP by electroporation is a useful method for the study of ara-CTP metabolism.

Arabinofuranosylcytosine Triphosphate↗
PubMed1990

Immunological aspects of asthma (prophylaxis).

A long follow-up study revealed that convalescent stage children still have the potency to have an immediate type hypersensitivity reaction on exposure to mite antigen, with a high titer of mite specific IgE in their sera, but they are free from asthmatic attacks because of the reduction in the amount of mite antigen in the body, as shown by the reduction in the amount of mite specific IgG. We also made a prospective study to see whether early elimination of the allergen has any beneficial effect on the cessation of the development of allergic diathesis thereafter. Our study suggested that early elimination of food allergen in infancy not only improved clinical manifestations but also had a protective effect on the progression of the allergic march so far as production of reaginic antibodies was concerned: production of total IgE and mite specific IgE was kept to a minimum.

Adolescent↗
PubMed1990

Treatment of pediatric malignant tumors with VP-16. West Japan Pediatric Oncology Group.

The West Japan Pediatric Oncology Group studied the treatment of pediatric malignant tumors with VP-16 from December 1984 to March 1988. Study subjects were divided into two groups. One group received only VP-16, while the other received VP-16 combined with other anti-tumor agents. VP-16 evaluation was possible in a total of 116 cases. The efficacy rate was calculated by considering both complete and partial remission as effective. The efficacy rate for VP-16 alone was 87.5% for primary cases of ANLL and 100% for primary cases of histiocytosis. The efficacy rates for combination therapy were as follows: 92.6% for primary cases of ANLL, 66.7% for primary cases of histiocytosis, 45.5% for relapsed cases of ANLL and 66.7% for relapsed cases of ALL. Bone marrow suppression was seen in the form of leukopenia and thrombocytopenia for 2 to 3 weeks after VP-16 administration. Alopecia, mucositis and gastrointestinal symptoms were also observed, but they presented no significant problem. From our results, we believe that chemotherapy including VP-16 is effective for remission induction therapy in primary cases of ANLL and for salvage therapy in relapsed leukemia. Additionally, VP-16 is considered to be effective for the treatment of histiocytosis.

Adolescent↗
PubMed1990

Juvenile nephronophthisis diagnosed from glucosuria detected by urine screening at school.

We describe the case of an 11-year-old girl in whom glucosuria detected by urine screening at school was the first clue to the diagnosis of juvenile nephronophthisis (JN). On admission, she showed renal failure with combined proximal and distal tubular defects and progressive deterioration of renal function. JN should be considered in children with glucosuria.

Child↗
PubMed1990

Biochemical study on the critical period for treatment of the mottled brindled mouse.

Hemizygous mottled brindled mice (Mobr/y mice) were treated by subcutaneous injection of copper and were decapitated on postnatal day 14. Cytochrome c oxidase (COX) activity of the brain mitochondria in the mice given 10 micrograms of copper/g on day 4 or 7 showed significant increases compared with that of untreated Mobr/y animals, and these mice had no neurological symptoms. Mice given 10 micrograms of copper/g on day 12 showed neither increases in COX activity nor clinical improvement. The brain levels of copper, noradrenaline, and dopamine in the mice treated on day 12 were the same as those in animals treated on day 4 or 7. The in vitro activities of dopamine-beta-hydroxylase of the brain were also the same among the treated mice, irrespective of the date of treatment. The results indicate that delays in copper treatment produce irreversible changes in COX activity of the brain and lead to clinical unresponsiveness to treatment.

Animals↗