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Biomedical subjects

M Umemoto

Publications and source records attributed to M Umemoto.

At least 73 records · Page 4Linked to original sources
PubMed1994

Failure of forskolin to elevate the endocochlear potential in kanamycin-poisoned animals.

The effect of forskolin (FSK) on the endocochlear potential (EP), K+ activity (AK), Na+ activity (ANa) and Cl- activity (ACl) in scala media (SM) was compared between normal and kanamycin (KM)-poisoned guinea pigs by means of double-barrelled ion-selective microelectrodes. The perfusion of the scala vestibuli (SV) with FSK (200 microM) produced EP elevation in normal animals whereas FSK failed to do it in KM-poisoned animals. FSK increased ACl of SM with no significant change in AK and ANa of SM in both groups of animals. Histological examination of KM-poisoned animals showed damaged outer and inner hair cells with an intact appearance of the stria vascularis. The mechanism underlying the failure of FSK to elevate the EP in KM-poisoned animals is discussed.

Animals↗
PubMed1994

Role of breast milk in acquisition of cytomegalovirus infection.

The prevalence of IgG antibody against cytomegalovirus (CMV) was compared between the age-matched (0 month to 2 years of age) groups of 212 breast-fed children and 223 bottle-fed children to examine the role of breast milk for acquisition of CMV. Mothers of both groups of children were also examined for CMV IgG antibodies. Both the breast-fed and bottle-fed children groups showed high seropositivity for CMV at 0 to 2 months of age, which gradually decreased and bottomed at 6 to 8 months of age. Thereafter, in the breast-fed children group, the seropositivity rate increased up to 70% by 1 year of age. In contrast, in the bottle-fed children group, the seropositivity rate remained at the bottom level of lower than 30%, without showing any apparent increases. The serological data of the children whose mothers were confirmed to be seropositive, revealed that mother-to-child transmission of CMV occurred in 11 of 17 (64.7%) of the breast-fed children and in 24 of 87 (27.6%) of the bottle-fed children. All the bottle-fed children born to seronegative mothers remained seronegative for CMV up to 1 year of age. The bottle-fed children showed significantly lower seropositivity than the breast-fed children, although most of both groups of children were born to seropositive mothers. The results strongly suggested that about 40% of the breast-fed children acquire CMV via breast milk and breast-feeding has certain protective effects on congenital CMV disease in the offspring.

Antibodies, Viral↗
PubMed1994

Impact of serum antibodies to p40tax gene product in the intrafamilial transmission of human T cell leukemia virus type I.

We examined the sera of family members of human T cell leukemia virus type I (HTLV-I) seropositive pregnant women who had visited Kagoshima City Hospital since 1986, and studied the routes of transmission of HTLV-I. A new enzyme linked immunosorbent assay (ELISA) for detecting the antibody to an HTLV-I tax gene product, p40tax, has recently been developed. By this ELISA method, the positive rate of anti-p40tax among HTLV-I seropositive subjects, including 96 pregnant women (index subjects), 26 mothers, 13 husbands, and 13 children was investigated. The percentage positive for anti-p40tax among pregnant women, mothers, husbands, and children was 41.6, 50, 53.8 and 53.8%, respectively. This means that the positive rate of anti-p40tax remains almost constant with increasing age. The rate of mother-to-child transmission of HTLV-I was significantly higher in p40tax seropositive (29.6%) than in seronegative mothers (8.1%). The positive rate of anti-p40tax in transmission from husband to wife (29%) and through blood transfusion (17%) was lower than the overall prevalence (46%). Thus, these data suggest that p40tax antibodies are associated with the frequency of HTLV-I transmission and with the differences in the transmission routes.

Adolescent↗
PubMed1994

Fine structural aspects on auditory hair cell degeneration in the budgerigar, Melopsittacus undulatus, as induced by kanamycin.

The effects of kanamycin, an antibiotic of the aminoglycoside group, on the auditory sensory epithelium of the budgerigar, Melopsittacus undulatus, were examined using both scanning and transmission electron microscopes. Results show that the threshold of the auditory brainstem response increased in birds treated with kanamycin 200 mg/kg for 49 days. While the auditory sensory epithelium of the normal budgerigar consists of short and tall hair cells, and supporting cells, following kanamycin administration, the middle to proximal region of the epithelium of the inner ear showed degenerative changes, with the other parts remaining apparently intact. In the damaged region, the short hair cells were flattened, and the tall ones became heterogeneous in shape. Both types of cells contained many dense bodies in their cytoplasm; they were rounded in shape and homogeneously dense. Severely degenerated tall hair cells also contained many large vacuoles with heterogeneous contents. Because the dense bodies and large vacuoles were positive for acid phosphatase reaction, they were respectively judged to be primary lysosomes and secondary lysosomes containing degenerating cell debris. Most supporting cells in the impaired region were lower in cytoplasmic electron density, and their apical surface became enlarged in area. Some flattened short hair cells were situated on the apical part of the swollen supporting cells. This finding suggests that the short hair cells are pressed toward the scala media by the supporting cells.

Animals↗
PubMed1994

Strial dysfunction in a melanocyte deficient mutant rat (Ws/Ws rat).

A homozygous mutant rat at the white spotting (Ws) locus showing a deficiency of melanocytes has recently been found (4, 5). The function and morphology of the inner ear of the Ws/Ws rat were examined by auditory brainstem response (ABR), endocochlear DC potential (EP), and electron microscopy. The mean ABR threshold of the Ws/Ws rat was significantly higher than that of the control +/+ rat. Most Ws/Ws rats showed no or very little EP. In electron microscopy, the stria vascularis of the Ws/Ws rat proved to be very thin and flat with poor interdigitation of marginal cells, and absence of intermediate cells. The organ of Corti appeared to be intact in both the +/+ rat and the Ws/Ws rat. These electrophysiological and morphological findings suggest that the Ws/Ws rat suffered from severe hearing loss caused by strial dysfunction.

Acoustic Stimulation↗
PubMed1994

[Application of non-radioisotopic in situ hybridization to the inner ear--expression of osteopontin].

Osteopontin (OPN) is considered to be a non-collagenous bone matrix protein which is involved in the ossification process. However, OPN has recently been observed in ectopic sites such as the kidney and nervous tissues. In the present study, expression of OPN mRNA was examined in the rat inner ear by non-radioisotopic in situ hybridization. Signals of OPN mRNA were observed in the marginal cells of the stria vascularis, spiral ganglions, vestibular sensory hair cells and vestibular dark cells. OPN protein was detected only in otoliths by immunohistochemistry. The reasons for the presence of OPN mRNA in the cochlea and dark cells of the vestibulum were unclear. On the other hand, findings of the sacculus and utriculus suggest that OPN is one of the protein components of rat otoliths and that vestibular sensory hair cells are involved in the production of otoliths.

Animals↗
PubMed1994

[Official inspection estimated production of coal-tar dyes (including dye aluminum lakes) in 1993-1994].

The number of official inspections of coal-tar dyes and their aluminum lakes from April 1993 till March 1994 were 734 in total, with the quantity which passed inspection amounting to 213 tons in Japan. Data for production by color for each month are summarised in Table 1, and by each producing company in Table 2. The food coal-tar dye produced in the largest quantity was Food Yellow No. 4, occupying a 42.9% proportion of the total during this period.

Chemical Industry↗
PubMed1993

Histochemical and ultrastructural pathology of skeletal muscle in a patient with abetalipoproteinemia.

Pathological examination was carried out of the skeletal muscle of an 8-year-old boy with abetalipoproteinemia. The patient complained of diarrhea, and showed a deficiency of betalipoprotein, decreased fat-soluble vitamins, acanthocytosis and a mild increase in serum creatine kinase. The prominent histochemical finding was punctate deposits of acid phosphatase activity in most fibers. Ultrastructural lesions revealed a number of giant lysosomes. Although these pathological findings seemed to be related to vitamin E deficiency, other pathological findings such as concentric laminated bodies or filamentous bodies were also observed. The clinical course and the changes in the pathological findings in our patient after long-term vitamin E therapy need to be observed.

Abetalipoproteinemia↗
PubMed1993

Low R-wave amplitude in the right precordial leads in children with symptomatic doxorubicin cardiomyopathy.

Electrocardiographic (ECG) findings were studied in four patients with doxorubicin cardiomyopathy. In all patients with congestive heart failure (CHF), the ECGs had a low R-wave and low R/S ratio in lead V1. Our study suggests that increased injury to myocardial cells in the regions of the anterior septum and anterior left ventricular wall may be important in the pathogenesis of doxorubicin cardiomyopathy. Eight years later, cardiac recovery from CHF occurred with a normal ECG and left ventricular ejection fraction in one patient, indicating that CHF may be reversible in certain cases.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Effect of dietary protein and urea on in vitro caecal ammonia production from urea and uric acid in cockerels.

1. Single Comb White Leghorn adult cockerels were fed on 50 g/kg protein diet, 200 g/kg protein diet or 50 g/kg protein diet plus urea and in vitro ammoniagenesis from urea and uric acid in the caeca was determined. 2. Four-fold protein intake caused about 4.6-fold increase in caecal ammonia production from urea (P < 0.05), and tended to increase it from uric acid as compared with 50 g/kg protein-fed birds. 3. Dietary urea significantly increased caecal ammonia production from urea and uric acid by about 2 and 3 times as much as those of control birds, respectively (P < 0.05). 4. It is concluded that increased protein intake and the feeding of urea are able to induce ammoniagenesis from urea and uric acid in the caeca of fowls.

Animals↗
PubMed1993

Transmission routes of HTLV-I: an analysis of 66 families.

HTLV-I transmission routes were found for 66 carrier pregnant women by studying sera, from the carrier pregnant women, their mothers, and their husbands, and by obtaining detailed family histories at interview. Forty-one cases (62.1%) were considered to be instances of vertical transmission, 15 (22.8%) of sexual transmission, 6 (9.1%) of blood transfusion, and 4 (6.1%) undecided. To date, most cases of adult T-cell leukemia (ATL) have been considered to result from vertical transmission. Our results therefore imply that about 30% (22.8% + 9.1%) of the carrier pregnant women are at minimal risk of ATL. Moreover, in case of presumed husband-to-wife transmission, more than half (6/11) were infected between one year and four years after marriage.

Adolescent↗
PubMed1993

Neutralizing antibody to vesicular stomatitis virus (HTLV-I) pseudotype in infants born to seropositive mothers.

Breast feeding is the major route of mother-to-child transmission of human T-cell leukemia virus type I (HTLV-I). Our experiments with rabbits have shown that passive immunization is capable of blocking cell-to-cell infection of HTLV-I by blood transfusion or breast feeding. In this study, sera were collected serially from 3 infants born to seropositive mothers and were tested for the presence of neutralizing antibody to vesicular stomatitis virus (HTLV-I) pseudotype as well as antibodies to viral structural proteins. There was a good correlation between neutralizing and viral antibody titers, both of which were detectable until 3-6 months after birth. Whether maternally transmitted neutralizing antibody is protective against perinatal infection of HTLV-I remains to be studied.

Adult↗
PubMed1993

The ultrastructure of the basilar papilla of the budgerigar's inner ear.

The basilar papilla in the inner ear of the adult budgerigar was studied by scanning and transmission electron microscopy. The sickle-shaped basilar papilla has short hair bundles on the proximal tip and long ones on the distal tip. The tectorial membrane shows a honeycomb-like pattern and enclosed a hair bundle in its alveolus. The papilla consists of two different types of hair cells; short and tall hair cells. The short hair cells with large efferent nerve endings are located on the free basilar membrane in the inferior part. The tall hair cells with large afferent nerve endings are located in the superior part. The similarity and difference of the structure are discussed between the budgerigar and other birds, and between birds and mammals.

Animals↗
PubMed1993

Electron microscopical observations of melanin in the endolymphatic sac.

Endolymphatic sacs of pigmented guinea pigs were examined by light and electron microscopy. Melanocytes were located not only in the subepithelial connective tissue but also in the intercellular spaces between the epithelial cells. They projected their dendrites into the epithelium extensively. Melanosomes in several stages of maturation and well-developed Golgi apparatus were seen in the cytoplasm of the melanocytes. Melanosomes were also observed in the membrane-bound vacuoles of the epithelial cells. These findings suggest that melanocytes in the endolymphatic sac are highly capable of producing tyrosinase, synthesizing melanin and transferring melanosomes to the epithelial cells, while melanocytes in the other parts of the inner ear do not show signs of melanogenesis under normal conditions.

Actin Cytoskeleton↗
PubMed1993

[Estimated production by the official inspection of coal-tar dyes (including dye aluminum lakes) in 1992].

The number of official inspection of coal-tar dyes and their lakes from April in 1992 till March in 1993 were 711 in total. The quantity which passed inspection amounted to 201 ton in Japan. The production of color in each month was summarised in Table 1, and by each producing company in Table 2. The food coal-tar dye produced in the largest quantity was Food Yellow No. 4, occupying 40.7% during this period.

Chemical Industry↗