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Biomedical subjects

K Shiraki

Publications and source records attributed to K Shiraki.

At least 253 records · Page 14Linked to original sources
PubMed1991

Sympathetic nerve activity and renal responses during continuous negative-pressure breathing in humans.

A stretch stimulus of the cardiopulmonary receptors results in a diuresis and natriuresis in dogs due to a suppression of renal sympathetic nerve activity. In the present experiment, the stretch stimulus in humans was given by means of continuous negative-pressure breathing (CNPB), and muscle sympathetic nerve activity (MSNA), renal responses, and hormones were measured to examine whether MSNA response during CNPB correlated with the usual renal and hormonal responses for stretch stimulus of the cardiopulmonary receptors. Nine healthy males were subjected to CNPB at -11 mmHg for 60 min. MSNA in the peroneal muscle nerve fascicles was measured continuously before (pre-CNPB), during, and after CNPB (post-CNPB). A step and sustained decrease (P less than 0.05) in MSNA (30 +/- 6% for burst frequency and 37 +/- 4% for total activity from pre-CNPB level) was observed during CNPB and it returned to pre-CNPB level at post-CNPB. Urinary excretion increased by 58 +/- 18% (P less than 0.05) during CNPB, and the diuresis was entirely osmolal in nature because of a significant increase (P less than 0.05) in Na excretion and a constant free-water clearance. The plasma level of norepinephrine decreased significantly (P less than 0.05) during CNPB and remained decreased (P less than 0.05) at post-CNPB. A twofold increase (P less than 0.05) in plasma atrial natriuretic peptide and a 35 +/- 9% reduction (P less than 0.05) in plasma renin activity were observed during CNPB, whereas no change was observed in plasma aldosterone and arginine vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Selection of L cell sublines resistant to (E)-5-(2-bromovinyl)-2'-deoxyuridine.

A mouse thymidine kinase (TK) deficient L cell subline and L cell sublines biochemically transformed by herpes simplex virus TK were cultured in the presence of increasing concentrations of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) which inhibited the growth of all sublines, and resistant sublines were isolated. Their growth properties were dependent on the medium condition used for selection. One subline had lost viral TK activity, while another retained viral TK activity with altered sensitivity of TK to BVDU in comparison with that of the original subline. Growth characteristics and TK activity of sublines are discussed.

Animals↗
PubMed1991

The effect of human milk on DNA synthesis of neonatal rat hepatocytes in primary culture.

We studied the effect of human milk on DNA synthesis of neonatal hepatocytes to elucidate the physiologic role of human milk in growth of the liver. Neonatal hepatocytes were isolated from 5-d-old rats and cultured in serum-free medium. Human milk stimulated DNA synthesis of these hepatocytes in a concentration-dependent manner. The stimulatory activity of 7.5% (vol/vol) human milk plus 0.1 mumol/L insulin was five times that of control and was almost the same as that of 20 micrograms/L human epidermal growth factor (hEGF) plus insulin. The effect of human milk was additive with treatment with hEGF and insulin. The milk associated with prolonged jaundice of infants was significantly more active than the milk that was not associated with jaundice, although the concentration of hEGF was not different between the two types of milk. The mitogenic activity of milk was heat-labile, inactivated by DTT and stable after treatment with trypsin. Three peaks of the activity were detected in milk by gel filtration and the fraction containing proteins of molecular weight between 36,000 and 76,000 showed the highest activity. Anti-hEGF antibody did not inhibit this activity completely. These results suggested the presence of mitogens other than hEGF or a more active form of hEGF in human milk. The milk associated with breast-milk jaundice exerts a different influence on cell growth and may affect maturation of the liver function related to bilirubin metabolism. The mitogenic activity of milk might be important for growth and development of the liver in infants.

Animals↗
PubMed1991

Substance p-induced cutaneous and bronchial reactions in children with bronchial asthma.

We studied substance P-induced cutaneous and bronchial reactions in children with allergic disorders. Furthermore, inhibitory effects of lidocaine on these responses elicited by substance P were also studied. In the intradermal test, children with moderate or severe bronchial asthma showed significantly stronger reactions than controls. In bronchial challenge with substance P, children with bronchial asthma showed an increasing fall in FEV1 and V50 in proportion to the severity of their asthma. Concomitant use of lidocaine significantly inhibited not only substance P-induced intradermal erythema and wheal reactions but air flow limitations. It also inhibited histamine-induced erythema and house dust-induced wheal and erythema reactions. No adverse reactions to lidocaine were observed. These results suggest that substance P might play an important role in cutaneous and bronchial hypersensitivity reactions in humans and that lidocaine has an inhibitory effect on substance P-induced reactions.

Adolescent↗
PubMed1991

Effects of indocyanine green dye enhanced diode laser photocoagulation in non-pigmented rabbit eyes.

Dye enhanced photocoagulation using indocyanine green (ICG) and diode laser has recently been introduced for occlusion of the choroidal neovascular tissue of age-related maculopathy. However, the effects of photocoagulation generated only by dye enhancement have not yet been studied. To discover the threshold amount of ICG for the minimum effect of photocoagulation, various photocoagulation parameters were tried in the fundus of albino rabbit. That is to say, ICG dosage laser power and exposure time were varied at the range of 0.5 mg to 14.0 mg/Kg, 80 to 500 mW and 0.2 or 1.0 sec, respectively. Histopathologic evaluation revealed that the effect of the enhanced photocoagulation was more marked in the choroid than in the retina, and was particularly noticeable in the large vessels in the deep layer of the choroid, even in lower threshold lesions. In clinical application, we should take into consideration the excessive reaction in the choroid.

Animals↗
PubMed1991

[Hepatitis C virus (HCV) infection in childhood].

We studied the prevalence of hepatitis C virus (HCV) infection in childhood by determining HCV antibody (Ortho Diagnostic Systems, USA). Among patients with post-transfusion non-A, non-B hepatitis, anti-HCV was positive in 8 (72.7%) out of 11 patients. On the other hand, only 1 (25.0%) out of 4 patients of the children with acute non-A, non-B hepatitis, and only 1 (20.0%) out of 5 with chronic non-A, non-B hepatitis patients were positive for anti-HCV. Among the infants with non-A, non-B hepatitis, anti-HCV was positive in 3 (7.5%) out of 40 infants. To demonstrate mother-to-infant transmission of HCV, we examined 7 infants born to 4 anti-HCV positive mothers for their GPT values and anti-HCV. Liver dysfunction occurred in all the infants but one. And 1 infant was positive for anti-HCV. This infant with positive anti-HCV and liver dysfunction was considered to be a case of mother-to-infant transmission of HCV. And in the infants with liver dysfunction and negative anti-HCV, it was suggested that liver dysfunction occurred in association with HCV infection.

Child↗
PubMed1991

[Effect of intravenous administration of coagulation factor XIII concentrate on persistent pleural air leak].

We administered coagulation factor XIII concentrate intravenously to six patients suffering from persistent air leak with no evidence of bronchopleural fistulae They are those who had either failed to be healed in response to pleurodesis, intrapleural fibrin glue injection and surgery or had not received such treatment. Their blood coagulation factor XIII activity levels were less than 70% of the standard plasma level. In four of the six patients, air leak stopped within 10 days after the treatment begun. Because factor XIII plays an important role in wound healing, reduction in the activity level can be a cause of insufficient healing of pulmonary surface fistulae and may lead to persistent air leak. In such cases, intravenous administration of factor XIII concentrate increases the activity levels and may put an end to persistent air leak.

Adolescent↗
PubMed1990

Analysis of a glycoprotein of human herpesvirus 6 (HHV-6) using monoclonal antibodies.

The virus-specific polypeptides of human herpesvirus 6 (HHV-6) were studied. Six hybridoma clones secreting monoclonal antibodies were established. Localized cytoplasmic antigen and surface antigens were found in and on the infected cells, respectively, by using the immunofluorescent test with those antibodies. In the neutralization test, two clones (OHV3 and OHV9) neutralized HHV-6, but the other five monoclonal antibodies did not. When infected cells were labeled with [35S]methionine and the antigens were immunoprecipitated by OHV3 and OHV9 followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, two polypeptides with molecular weights of 98,000 (98K) and 92K were detected. Furthermore, it was found that these polypeptides were glycosylated, because they were labeled with [14C]mannose. Pulse-chase studies revealed that precursor molecules were cotranslationaly glycosylated to produce 98K glycoprotein and they were replaced by 92K glycoprotein. Endo-beta-N-acetylglucosaminidases H and F reduced those glycoproteins to putative precursor molecules of 75 kDa. This indicates that N-linked high-mannose sugars associate to 98K and 92K glycoproteins.

Animals↗
PubMed1990

Human herpesvirus 6 infection in renal transplantation.

The relationship between renal transplantation and human herpesvirus 6 (HHV-6) infection was studied. All 21 kidney donors examined had antibody to HHV-6 at the time of transplantation. The 21 kidney recipients also had detectable antibody to HHV-6 before transplantation--and, of these, 8 patients showed a significant increase of serum antibody titer against HHV-6 after transplantation. All these 8 recipients suffered severe kidney rejection. Furthermore, virus isolation from peripheral blood lymphocytes of 2 recipients who suffered rejection was attempted, and in both cases HHV-6 was isolated. Biopsy specimens of rejected kidneys of 9 other patients were examined for the presence of HHV-6 antigens, and in 5 of these specimens antigens were detected in the tubular epithelium, as well as in infiltrating histiocytes and lymphocytes. These results suggest that HHV-6 can infect renal tissues and that the infection may be correlated with rejection or with immunosuppressive therapy.

Adult↗
PubMed1990

Cardiovascular, renal, and endocrine responses in male quadriplegics during head-out water immersion.

The present study was undertaken to determine the relative influence of the action of the central nervous system on the mechanism of water-immersion-induced diuresis by comparing physiological responses of quadriplegic (QP) and normal subjects. After overnight fasting seven male QP subjects with complete cervical cord transections (C5-C8) and six normal men were tested before, during, and after 3 h of head-out immersion (HOI) in thermoneutral water (34.5-35.0 degrees C). The reversible increase in urine flow and the total urine volume (309 +/- 53 ml in 3 h) in QP subjects were comparable with that of the normal subjects (318 +/- 96 ml in 3 h). While osmolal excretion was increased in QP subjects, its magnitude was less when compared with that of normal subjects. Instead, the increased urine flow in QP subjects was characterized by increased glomerular filtration rate (GFR) and free water clearance, in contrast to a predominantly osmotic diuresis with no changes in GFR in the normal subjects. The HOI elevated (P less than 0.05) systolic pressure only in QP subjects, whereas the increase in cardiac output was the same in both groups. While plasma renin activity and aldosterone responses to HOI in QP subjects were comparable with those of normal individuals, plasma atrial natriuretic factor (ANF) in QP subjects was twofold higher (P less than 0.05) during HOI, and the approximately threefold increase in ANF (P less than 0.05) in QP subjects due to HOI was the same as that of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Changes in insulation of body tissue and wet suits during underwater exercise at various atmospheric pressures.

To clarify the independent changes of insulations of body tissues (Itissue) and wet suit (Isuit) in the wet-suited subject during underwater exercise, overall heat flow from the skin (Htissue) and wet suit (Hsuit) and esophageal (Tes), skin (Tsk), and wet suit temperatures were measured at 1, 2, and 2.5 atmospheres absolute (ATA) at critical water temperature (Tcw). The average Tcw in nine wet-suited men (23-38 yr) was 22.3 +/- 0.2, 26.3 +/- 0.2, and 28.0 +/- 0.4 degrees C (SE) at 1, 2, and 2.5 ATA, respectively. At Tcw of each pressure male volunteers wearing 5-mm neoprene wet suits completed three 2-h experiments while immersed up to the neck. During one experiment the subjects remained at rest, and in the other two they exercised on an underwater ergometer at two different intensities (2 and 3 met). Tes significantly declined (P less than 0.05) over 2 h from 37.1 to 36.5 degrees C during rest in each pressure. The 2-met exercise prevented Tes from falling in all pressures, and the 3-met exercise elevated Tes by 0.2-0.3 degrees C. There was no exercise-dependent difference in Isuit, but a pressure-dependent difference was remarkable. The Itissue at rest was identical for all pressures; however, it progressively decreased as a function of exercise intensity. It is concluded that overall Itissue is entirely determined by work intensity at Tcw, but not by atmospheric pressure. On the contrary, Isuit at Tcw is solely dependent on the pressure, but not on the work intensity.

Adult↗
PubMed1990

Splenic contraction during breath-hold diving in the Korean ama.

Major increases of hemoglobin concentration and hematocrit, possibly secondary to splenic contraction, have been noted during diving in the Weddell seal. We sought to learn whether this component of the diving response could be present in professional human breath-hold divers. Splenic size was measured ultrasonically before and after repetitive breath-hold dives to approximately 6-m depth in ten Korean ama (diving women) and in three Japanese male divers who did not routinely practice breath-hold diving. Venous hemoglobin concentration and hematocrit were measured in nine of the ama and all Japanese divers. In the ama, splenic length and width were reduced after diving (P = 0.0007 and 0.0005, respectively) and calculated splenic volume decreased 19.5 +/- 8.7% (mean +/- SD, P = 0.0002). Hemoglobin concentration and hematocrit increased 9.5 +/- 5.9% (P = 0.0009) and 10.5 +/- 4% (P = 0.0001), respectively. In Japanese male divers, splenic size and hematocrit were unaffected by repetitive breath-hold diving and hemoglobin concentration increased only slightly over baseline (3.0 +/- 0.6%, P = 0.0198). Splenic contraction and increased hematocrit occur during breath-hold diving in the Korean ama.

Adult↗
PubMed1990

Prevalence of obesity, leanness and anorexia nervosa in Japanese boys and girls aged 12-14 years.

Body weight and height of Japanese boys and girls aged 12-14 years were measured to calculate the prevalence of obesity, leanness and anorexia nervosa. In boys, the prevalence of obesity as well as leanness was significantly higher in the areas where population density was lower and among the boys who attended schools with smaller numbers of pupils. In the girls, these findings were similar to the boys. On the other hand, anorexia nervosa was found in girls only more commonly in the areas with higher population density and in the larger schools. These results suggest that higher prevalence of obesity in certain subjects may be associated with increased numbers of leanness but not with anorexia nervosa.

Adolescent↗
PubMed1990

Comparative assay of varicella skin test antigens by the ELISA and RPHA tests.

The antigenic potency of the varicella skin test antigens was assayed by reversed passive haemagglutination (RPHA) test using sheep red blood cells coated with zoster convalescent serum and by enzyme linked immunosorbent assay (ELISA) using anti-VZV sera or monoclonal antibody to gpI followed by an anti-IgG beta-galactosidase conjugate. Three kinds of varicella skin test antigens were compared: a soluble varicella skin test antigen, a modified soluble varicella skin test antigen, and a crude varicella skin test antigen. The RPHA test was suitable for the soluble and for modified soluble varicella skin test antigens but it was not suitable for the crude varicella skin test antigen. ELISA was applicable for all the three antigen types. It was possible to assess quantitatively the content of viral antigens in the same type of the skin test antigen, but not by comparing the different skin test antigen types. ELISA was more efficient in the quantitative assay of the amount of viral antigens than the RPHA test.

Animals↗
PubMed1990

Characteristics of increased urine flow during a dry saturation dive at 31 ATA.

Three male divers were subjected to a 7-day dry saturation dive at 31 ATA (New Seatopia). Urine samples were collected for measurements of electrolytes and creatinine for glomerular filtration rate (GFR) 5 times daily, at 3-h intervals during daytime (0700-2200 h) and once at night (2200-0700 h). Collections were taken for 2 days before (predive 1 ATA air), 7 days during 31 ATA exposure, and during 10 days of decompression and for 2 days at postdive 1 ATA air. Blood samples were taken after overnight fasting at each of the dive periods for measurements of atrial natriuretic factor (ANF), electrolytes, and other blood constituents. Compression to 31 ATA resulted in a twofold increase in urine flow accompanied by increases in excretion of osmotic substances (+40%) and sodium (+54%), and a reduction in urine osmolality (-32%). The increase in urine volume was greater (P less than 0.05) at night than day with no change in GFR between day and night, confirming the earlier findings. However, no change in plasma ANF was observed in spite of a sustained increase in daily sodium and water excretion at high pressure. These results suggest that the hyperbaric diuresis-natriuresis may not be directly mediated by the ANF release.

Adult↗