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H Masuda

Publications and source records attributed to H Masuda.

At least 343 records · Page 19Linked to original sources
PubMed1992

Mitotic activity in mice is suppressed by energy restriction-induced torpor.

We monitored core body temperature by telemetry in energy-restricted (201 kJ/wk) and control (397 kJ/wk) C57BL/6 and SHN/C3H F1 mice to determine whether torpor may be involved in the suppression of mitotic activities resulting from energy restriction. The energy restriction regimen employed inhibited the development of cancer and greatly extended longevity in both these mouse strains. Male and female C57BL/6 mice subjected to energy restriction from 4 wk of age and tested at 3 mo of age became torporific (body temperature less than 31 degrees C) at ambient air temperatures of 20-22 degrees C, whereas control animals stayed euthermic (greater than 35 degrees C). Energy restriction also induced torpor in 3- and 13-mo-old SHN/C3H F1 female mice, whereas 3-, 13- and 24-mo-old control mice were euthermic. Energy restriction decreased mitotic activities to approximately 30% of control values in both jejunum and epidermis in 3-mo-old female C57BL/6 mice maintained at 20-22 degrees C. However, this suppression of mitotic activities was antagonized by housing the energy-restricted mice at 30 degrees C for 2 wk, indicating that torpor plays a substantial role in suppressing mitotic activities in energy-restricted mice.

Animals↗
PubMed1992

The Role of beta-Galactosidases in the Modification of Cell Wall Components during Muskmelon Fruit Ripening.

The changes in activities of soluble beta-galactosidase and two forms of wall-bound beta-galactosidases extracted with NaCl and EDTA were investigated throughout the development of muskmelon (Cucumis melo L. cv Prince) fruits. DEAE-cellulose ion-exchange chromatography of soluble beta-galactosidase revealed the presence of two isoforms. Soluble isoform I was detected in all stages throughout the fruit development, whereas soluble isoform II appeared around 34 d after anthesis when fruit ripening initiated. Both NaCl- and EDTA-released beta-galactosidase activities also increased as ripening proceeded. The soluble and wall-bound forms behaved differently upon ion-exchange chromatography. Enzymological properties such as optimum pH, optimum temperature, K(m) values for p-nitrophenyl beta-d-galactopyranoside, and inhibition by metal ions were nearly similar in all forms. Molecular sizes of pectic polymers and hemicelluloses extracted from fruit mesocarp cell walls were shifted from larger to smaller polymers during ripening, as determined by gel filtration profiles. NaCl-released beta-galactosidase from cell walls of ripe fruits had the ability to degrade in vitro the pectin extracted from preripe fruit cell walls to smaller sizes of pectin similar to those that were observed in ripe cell walls in situ. Both soluble isoform I and II were able to degrade in vitro the 5% KOH-extractable hemicellulose from preripe fruit cell walls to sizes of molecules similar to those that were observed in ripe cell walls in situ. Soluble isoform I and the NaCl-released form from ripe fruits were able to modify in vitro 24% KOH-extractable hemicellulose from preripe cell walls to sizes of molecules similar to those that were observed in ripe fruits in situ.

Journal Article↗
PubMed1992

Novel isoform of Ca2+ channel in rat fetal cardiomyocytes.

1. Single cardiomyocytes of 18-day-old rat fetuses were isolated to characterize the cardiac Ca2+ channels in the fetal period, using whole-cell voltage clamp (Na+, K(+)-free external solution and K(+)-free internal solution), and depolarizing test pulses from a holding potential (HP) of -87 mV were applied. 2. The Ca2+ current was completely blocked by 2 mM-CO2+, but not completely blocked by the dihydropyridine (DHP) Ca2+ antagonist nifedipine. Nifedipine (3 microM) decreased the amplitude of the current (at -7 mV) by 65.9 +/- 3.4% (n = 20). At a HP of -47 mV, nifedipine decreased the Ca2+ current to about the same degree. Diltiazem (1 microM) did not block the nifedipine-resistant current which remained. 3. Nitrendipine, another DHP Ca2+ antagonist, had effects on the Ca2+ current similar to those of nifedipine. 4. The DHP-resistant current was not blocked by T-type channel blockers (Ni2+, tetramethrine) or an N-type blocker (omega-conotoxin). 5. In conclusion, rat fetal cardiomyocytes may have a unique type of Ca2+ channel (ICa(fe)), which decreases in amplitude and becomes less prominent during subsequent development.

Animals↗
PubMed1992

Stretch-activated anion currents of rabbit cardiac myocytes.

1. Stretch-activated anion currents were studied in sino-atrial and atrial cells using the whole-cell patch clamp technique. With continuous application of positive pressure (5-15 cmH2O) through the patch clamp electrode, the cell was inflated and the membrane conductance was increased. 2. Voltage clamp steps revealed that the stretch-activated currents had time-independent characteristics. The increase in membrane conductance was reversible on subsequent application of negative pressure to the electrode. 3. The reversal potential of the stretch-activated currents was shifted by 60 mV for a 10-fold change in intracellular Cl- concentration, while it was unaffected by replacement of Na+ in the extracellular solution by N-methyl-D-glucamine. Cell superfusion with Cl(-)-deficient solution (10 mM Cl-) reduced the amplitude of outward current. These findings indicate that the stretch-activated conductance is Cl- selective. 4. The sequence of anion permeability through the stretch-activated conductance was determined to be I-(1.7) > NO3-(1.5) > Br-(1.2) > Cl-(1.0) > and F-(0.6). SCN- appeared to be more permeant than I-. 5. The stretch-activated conductance was reduced by the Cl- channel blockers, 4,4'-dinitrostilbene-2,2'-disulphonic acid disodium salt, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid or anthracene-9-carboxylate (9-AC). Administration of furosemide or bumetanide had no effect. 6. The stretch-activated Cl- current was recorded even though intracellular Ca2+ ions were chelated by including 10 mM EGTA in the pipette solution. Neither the specific peptide inhibitor of cyclic AMP-dependent protein kinase (50 microM), nor the non-selective blocker of protein kinases, H-7 (20 microM), was effective in reducing the stretch-activated Cl- current, suggesting that the stretch-activated Cl- current is a novel type of cardiac Cl- current, which shows a different modulatory mechanism from that of other cardiac Cl- currents.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1992

[Clinical and epidemiological aspects of enteritis due to Salmonella hadar. I. Isolation of S. hadar from sporadic diarrhea--clinical and bacteriological study].

Before 1983, S. hadar was seldom isolated from man, animals, food or the environment in Japan: only one strain having been isolated from man and one from the environment. In subsequent years there has been a progressive increase in the number of isolations. S. hadar is now one of the commonest serotypes isolated from cases of sporadic diarrhea in Shizuoka Prefecture (Table 1). However, the epidemiology of S. hadar is not clearly understood. Reports on the clinical features of S. hadar gastroenteritis are also scarce. We examined the clinical symptoms of 15 cases of S. hadar gastroenteritis. S. hadar was encountered in patients of all ages. Infants and young children below 10 years of age constituted 47% of all cases. Seventy per cent of young children below 10 years of age experienced fever of more than 39 degrees C. This incidence was significantly higher than that of general Salmonella gastroenteritis observed in our previous study, in which fever of more than 38 degrees C was noted in 61% of the children. We found one case of presumptive person-to-person spread. No other household contacts of index patients suffered from diarrhea during the same period. Systematic examination for Salmonella contamination was performed for poultry farms, broiler chickens, broiler processing plants and meat on the market. 259 Salmonella strains were isolated from 1197 samples. S. hadar accounted for 37.1% (96) of all isolations (259). A drug resistance test was performed for 51 strains of the diarrhea cases and 67 strains of the environment. The pattern of the distribution of MICs of 9 drugs was similar in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[Clinical and epidemiological aspects of enteritis due to Salmonella hadar. II. Environmental contamination by Salmonella hadar in Shizuoka Prefecture--studies on the feasibility of reducing S. hadar infection].

A systematic examination was performed for environmental food contamination by Salmonella in poultry farms, broiler chickens, broiler processing plants and meat on the market. Salmonella was isolated from 219 of 1197 samples and the serotypes showed a wide distribution. (Table 1-1). S. hadar accounted for 37.1% (96) of all isolations (259). The contamination rate of broiler chickens on arrival at broiler processing plants is relatively low. However, in the broiler processing plants, containers, processing machinery, cooling water and slaughters were highly contaminated by Salmonella, S. hadar being the most prominent serotype in the plants. 64% of chicken meat on the market was contaminated by Salmonella, S. hadar being the second most prominent serotype. 11% of the pork and none of the beef or horseflesh was contaminated by Salmonella. These results indicate that poultry is the main source of S. hadar infection in humans. However, no S. hadar was isolated from cultures of 119 samples of feed for chickens from each delivery (Table 1-1). Thus, as the main source of infection by S. hadar of broiler chickens, an association with the feed seems to be ruled out. S. hadar was isolated at three of 18 poultry farms within Shizuoka Prefecture. Follow-up studies were performed at the three poultry farms which revealed that in two of them, Salmonella was completely eradicated on completion of disinfection. In the other one farm, which is still being disinfected, various strains of Salmonella including S. hadar still survived. We conclude that the main cause of the problem is the magnification of contamination of Salmonella-free material during the process at the broiler processing plants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Difference in dilatation between endothelium-preserved and -desquamated segments in the flow-loaded rat common carotid artery.

To study arterial dilatation in response to increased flow, we observed the bilateral common carotid arteries (CCAs) of 10 16-week-old rats that were maintained for 8 weeks after construction of an arteriovenous (AV) fistula between the left CCA and the jugular vein at a level 20 mm distal from the aortic orifice. The flow in the left CCA increased 11-fold and that of the right CCA increased twofold compared with values before surgery. The left CCA showed complete desquamation of endothelial cells in the distal one third of the segment proximal to the AV fistula. In the left CCA the endothelium-preserved area dilated significantly (the luminal radius was 1.34 times larger than control; p less than 0.001, n = 4) with a significant increase of the cross-sectional area of the media (p less than 0.01, n = 4) and showed high wall shear stress (70 +/- 11 dynes/cm2 near the aortic orifice). In contrast, the endothelial cell-desquamated area did not dilate but did show very high wall shear stress (231 +/- 23 dynes/cm2) without any intimal smooth muscle cell proliferation. The right CCA dilated significantly (luminal radius was 1.07 times larger than control; p less than 0.001, n = 4) with a wall shear stress of 30 dynes/cm2 near the brachiocephalic orifice. All CCAs retained their fundamental arterial structure. We conclude that in the rat CCA, arterial dilatation in response to increased flow is a gradual remodeling process related to the presence of endothelial cells that have been influenced by the level of flow increase.

Animals↗
PubMed1992

Evidence of intrathyroidal accumulation of TSH receptor antibody in Graves' disease.

To clarify the intrathyroidal accumulation of TSH receptor antibody (TR-ab) produced in the thyroid, adrenalin was injected directly into the thyroid artery of patients with Graves' disease during surgery, allowing serial determination of the TR-ab levels in the thyroidal venous blood. Nine surgical patients (3M and 6F) with Graves' disease and receiving anti-thyroid drugs preoperatively for a period of one to four years were enrolled in this study. Comparison between pre- and posttreatment TR-ab levels revealed continuous increments from the pretreatment levels within 15 min of the injection in five (55.6%) of the nine patients. In three of the five patients, TR-ab levels that had been negative before adrenalin injection became positive 1 min after injection. It is assumed that the increase in the TR-ab level is due to adrenalin-induced constriction of the capillaries in the thyroid tissues, resulting in a voluminous flow of the TR-ab retained in the thyroid into the vein. These findings indicate that the TR-ab level in the peripheral blood does not necessarily reflect precisely the abnormal immunological condition in the Graves' thyroid.

Adolescent↗
PubMed1992

[Apparatuses for obtaining continuous 24-hour records of water intake and urinary output in dogs].

Two apparatuses were constructed to obtain continuous records of water intake and urinary output in a dog. As a validation of their accuracy, daily patterns of these measurements were observed on a beagle using these two apparatuses during non-treatment and treatment of the diuretic drug, flosemide. During the non-treatment, water intakes increased after feeding, but urinary outputs did not show a regular pattern. These patterns were the same as the previously reported patterns. During the treatment, urinary output increased within one hour after treatment. These results show these apparatuses are useful in measuring water intake and urinary output continually on the experimental dog.

Animals↗
PubMed1992

Species difference in susceptibility to phorbol myristate acetate-induced leukopenia and lung injury: rat vs. dog.

Phorbol myristate acetate (PMA) was administered intravenously in a single dose to rats (400 micrograms/kg) and in a single and repeated doses to dogs (40 micrograms/kg). Severe leukopenia was observed in both species. The leukopenia in rats was due to a decreased number of both lymphocytes and neutrophils while the leukopenia in dogs was mainly due to a decreased number of neutrophils. The rats recovered from leukopenia much faster than the dogs. The dog which received a single injection developed focal fibrosis in the lungs. Rats showed only slight localized hemorrhage in the lungs, although the rats received a ten-fold larger dose of PMA than the dogs. Lungs of dogs which received multiple injections revealed severe hemorrhagic lesions in most alveoli. Lung lesions induced by PMA are thought to be mediated by activated leukocytes. This suggests that the severity of lung lesion correlates with the degree and duration of neutropenia. In conclusion, intravenous administration of PMA caused lung damage in rats and dogs. However, rats show much less sensitivity to PMA than dogs, resulting from the different response of leukocytes to PMA.

Animals↗
PubMed1992

[A case of staphylococcal enterocolitis caused by methicillin resistant Staphylococcus aureus].

Recently, the frequency of methicillin resistant Staphylococcus aureus (MRSA) infection has been increasing. We experienced a case of postoperative enterocolitis due to MRSA. The patient was an 81-year-old male with benign prostatic hypertrophy. Urine leakage from the penrose drain tube appeared 1 day after suprapubic prostatectomy. We had used intravenous infusion of antibiotic agents including cefodizine (CDZM), imipenem (IPM/CS) and cefmetazol (CMZ). He developed severe diarrhea, high fever, oliguria, leg edema and ascites 24 days after the operation. MRSA was detected from his feces. Toxic shock syndrome toxin-I (TSST-I) was produced by this bacteria the coagulase type of which was type II. The patient was treated with oral vancomycin (1 g/day), to which this bacteria showed sensitivity and the patient showed, improvement, including symptoms, leucocytosis and serum CRP level 12 days after administration of vancomycin.

Administration, Oral↗
PubMed1992

[Primary carcinoma in situ of the ureter: a case report].

A 47-year-old man presented with gross hematuria and left lower abdominal dull pain of 6-weeks duration. Cystoscopic examination revealed bloody efflux from the left ureteral orifice but no tumor in the bladder. Retrograde pyelogram showed irregular stricture of middle portion of the left ureter. Cytologic studies of the voided urine and left ureteral urine were positive for cancer, and nephro-ureterectomy with excision of a bladder cuff was carried out. The surgical specimen showed no intraluminal mass but histologically, transitional cell carcinoma in situ with G3 anaplasia and squamous metaplasia was found in the narrowed portion of the ureter. Followup examinations, including exfoliative urinary cytology, cystoscopy and IVP revealed no abnormalities until intravesical recurrence was confirmed 34 months later. Transurethral resection of bladder tumor was performed and superficial papillary transitional cell carcinoma with G2 anaplasia was found in the trigone of the bladder. Followup examinations for the last one year have revealed no abnormalities.

Carcinoma in Situ↗
PubMed1992

Effects of simulated Fowler-Stephens orchiopexy on testicular structure and function in rats.

To determine the effects of the Fowler-Stephens orchiopexy (FSO) on testicular structure and function, young rats underwent simulated FSO and concurrent contralateral orchiectomy, unilateral orchiectomy, or no operation. Rats were killed at 1, 2, 4, 6, 8, and 10 weeks postoperation, and serum testosterone, as well as testicular concentrations of the enzymes LDH & SDH, protein markers of testicular germinal cell development, were measured at the time of death. Although LDH and SDH concentrations decreased by 45 per cent in testes after simulated FSO at 4 weeks, control testes showed a 5 per cent increase in these enzymes. Serum testosterone decreased to one-fourth the initial value in rats after FSO, whereas control rats showed a slight increase. Within 2 weeks after simulated FSO, spermatocytes and sperm were sparse and there was marked disruption of tubular morphology; after 4 weeks interstitial fibrosis became prominent. Only a rare testis with good collateral vessels and resultant good histologic appearance and enzyme profile survived the FSO procedure, and these testes were considerably smaller than the controls.

Animals↗
PubMed1992

[Evaluation of hypercoagulable state in patients with malignancies by using prothrombin fragment F1 + 2].

In order to elucidate the activation of the coagulation cascade in patients with malignant neoplasms, we measured the levels of plasma prothrombin fragment F1 + 2, which is liberated in the process of thrombin generation. Twenty healthy adults (Group A), 29 patients with malignancies not complicated with DIC (Group B) and 4 patients with DIC (Group C) were evaluated. The values of F1 + 2 in Group C (2.38 +/- 0.55 nmol/l) were significantly higher (p < 0.01) than those in Group A (0.52 +/- 0.19 nmol/l) and B (0.86 +/- 0.68 nmol/l). Many patients in Group B showed higher levels of F1 + 2 compared to normal subjects, however, no significant differences were found between Group A and B. With respect to other coagulation molecular markers such as TAT, D-Dimer and PIC, F1 + 2 levels revealed positive correlation to those levels. Concerning the clinical course of DIC, elevated levels of F1 + 2 normalized much rapidly than those of TAT and D-Dimer by continuous administration of heparin. In conclusion, the measurement of plasma F1 + 2 is important in monitoring the activation of coagulation system in patients with malignancies, especially with respect to early detection and treatment of DIC.

Aged↗
PubMed1992

[Histological evidence of prolonged coronary artery spasm in a necropsy case of recurrent myocardial infarction].

A 69-year-old male had acute inferior infarction during an operation of an aneurysm of the abdominal aorta and died from multiple organ failure 3 weeks after the operation. His initial coronary angiogram (CAG) showed no significant stenosis, but repeated CAG showed that the patients had developed a prolonged spasm in the mid-portion of the right coronary artery. Histologically, we observed eccentric luminal narrowing with atheromatous plaque where the spasms had been demonstrated, and a "waving form" of elastic fibers accompanied by intimal thickening in the opposite site of the atheromatous plaque. These findings suggest that organic stenosis may be underestimated angiographically because of compensatory enlargement of the non-atheromatous site in some patients with coronary artery spasm, and prolonged spasms may augment organic stenosis by following intimal thickening.

Aged↗
PubMed1992

[Primary sclerosing lipogranuloma of the male genitalia: report of three cases].

Recently, genital sclerosing lipogranuloma having no history of trauma and foreign body infusion are more common in Japan. We report three cases recently encountered in which tumors were diagnosed as sclerosing lipogranuloma on histological examination. In case 1, lipid analyses of the tissues by infrared absorption spectrometry proved that it was endogenous in origin.

Aged↗