Search PubMed⌕ Search

Biomedical subjects

T Kitamura

Publications and source records attributed to T Kitamura.

At least 523 records · Page 29Linked to original sources
PubMed1991

Electrical stimulation of hypothalamic periventricular nucleus is followed by a large rebound secretion of growth hormone in unanesthetized rats.

The effect of electrical stimulation of the hypothalamic periventricular nucleus (PVN) on plasma GH profile was studied in unanesthetized female Wistar rats. A bipolar concentric electrode was implanted into the PVN, hypothalamic ventromedial nucleus (VMH), or intervening area between the PVN and VMH. Serial blood specimens were collected from an indwelling right atrial cannula. Plasma GH levels were reduced significantly during electrical stimulation of PVN, and a large rise of plasma GH levels followed after cessation of stimulation. An identical plasma GH profile was observed in response to the repeated stimulation. This rebound secretion of GH was completely inhibited by the administration of rat GRF antiserum. The effect of electrical stimulation of VMH on plasma GH levels was similar to that of PVN stimulation. However, the stimulation of hypothalamic area intervening between PVN and VMH was not followed by a surge of GH secretion. Since a continuous exposure of somatotrophs to GRF even in a concurrent presence of somatostatin (SS) is known to induce attenuation of the GH response to GRF through receptor effect, the results suggest that the release of endogenous GRF is augmented following the cessation of electrical stimulation of neurons providing hypophysiotropic SS.

Animals↗
PubMed1991

The factor structure of the General Health Questionnaire in a Japanese high school and university student sample.

Factor structures of the 60- and 30-item versions of the General Health Questionnaire (GHQ) were explored, using data collected from 236 Japanese high-school and university students. The 60-item version produced factors interpretable as social functioning, anxiety, somatic symptoms, and severe depression; the 30-item version produced general dysphoria, social functioning, depressive thoughts, difficulty in concentration and insomnia. Although the two versions of the GHQ produced the same number of factors, their structures differed in content. Thus it may be necessary to examine the factor structures of the GHQ when using it in a study of a population containing subjects with different cultural backgrounds.

Adolescent↗
PubMed1991

Growth hormone secretion in stalk-sectioned rats.

Idiopathic pituitary GH deficiency appears to result from neonatal disruption of hypophyseal portal vessels in the majority of patients. To examine the mechanism of GH deficiency associated with the disease, the effect of pituitary stalk section on GH secretion was studied in rats. Adult male rats were subjected to stalk section without inserting an impermeable membrane between the cut ends. They were studied 3 to 4 weeks after surgery. In stalk-sectioned rats, pituitary weight, body weight and hypothalamic SRIH content were significantly reduced as compared with sham-operated rats. Hypothalamic GHRH content, plasma T3, T4, corticosterone and testosterone levels, and weights of testes remove and adrenal glands were comparable in the two groups. Plasma GH profiles of sham-operated rats showed characteristic periodic pulses occurring at 2.5-3 h intervals with intervening trough period. In stalk-sectioned rats, plasma GH levels were low small fluctuations, but GH levels were significantly higher than trough levels of sham-operated rats. The amount of GH secreted during a 6-h period as measured by planimetry was significantly reduced. To ascertain the regeneration of hypophyseal portal vessels, post SRIH rebound in GH secretion, which requires the presence of endogenous GHRH, was examined. Withdrawal of exogenous SRIH infusion triggered a large rebound GH secretion whose magnitude did not differ between groups. In stalk-sectioned rats, GH response to met-enkephalin analogue, FK 33-824, was not observed, whereas prolactin response to the secretagogue was observed in the majority of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Tumor viruses in urology with special respect to human papillomavirus and human polyomavirus].

The advent of molecular biology has made a great progress for HPV research. It is now considered that more than 90% of cervical carcinomas are caused by HPV infection. However, it is the problem that penile lesions associated with cancer-related HPV types are subclinical, resulting in acceleration of HPV transmission by male reservoir. We urologists should make an effort to treat HPV infection and to prevent HPV prevalence. On the other hand, any pathological role of JCV has not been revealed in humans except for PML. Nowadays, it is considered unlikely that there is a pathogenetic relationship between JCV and human tumors. However, since archetypal JCV has been discovered, it has been thought that archetypal JCV receives DNA rearrangements during latency in the kidney by some immunological derangements of the host and is subsequently altered to PML-type JCV. Additionally, there is a possibility that archetypal JCV causes asymptomatic hematuria. More investigation will be necessary for elucidating pathological role of archetypal JCV in the field of urology.

Base Sequence↗
PubMed1991

Analysis of common epitopes on gag proteins of HIV-1, HIV-2 and SIV[AGM] using monoclonal antibodies against HIV-1.

Five monoclonal antibodies (MoAbs) to gag proteins of HIV-1 were prepared in mice. Western blot analyses showed that three clones recognized p24 and the other two p17. Among the three MoAbs recognizing p24, all recognized two of three strains of HIV-2. The spectra of reactions to SIV[AGM] of these MoAbs against p24 were different from one to another; K3-24 recognized all four strains of SIV[AGM], L6-24 three of them, and K5-24 none of them. Of the two MoAbs recognizing p17, K7-17 recognized two of the three strains of HIV-2 but not any SIV[AGM] strain, and the other clone, L14-17 recognized none of analogous proteins of HIV-2 nor of SIV[AGM]. These results demonstrate that the gag proteins of HIV-2 and SIV[AGM] share some common epitopes with those of HIV-1 which are heterogenic in some degree among the different isolates.

Animals↗
PubMed1991

Induction of heat shock protein and thermal sensitivity of mammalian cells maintained at low culture temperature.

Effects of low culture temperature on the induction of heat shock proteins in FM3A cells by a heat shock and on the thermal sensitivity of the cells were examined. FM3A cells maintained at 33 degrees C could not induce hsp70 during continuous heating or after a short heat shock at either 39, 42, or 45 degrees C, although FM3A cells maintained at a normal culture temperature of 37 degrees C can induce the synthesis of hsp70. Furthermore, the cells maintained at 33 degrees C were more sensitive to the subsequent heat shock than the cells maintained at 37 degrees C. Thus, the culture temperature of the mammalian cells may be an important factor for the induction of hsp70, and hsp70 may play an important role to protect or repair the thermal damage of cells.

Animals↗
PubMed1991

Calculation of efficacy of acellular pertussis vaccine from the number of pertussis patients and vaccinees in three areas.

A study is presented of the efficacy of acellular pertussis vaccine based on the number of pertussis patients and its relationship to vaccination rate in three demographic areas of Osaka Prefecture, Japan. In three separate areas within Osaka Prefecture, the pertussis vaccine is given to children three to six months of age, and in the other two it is given to children two years of age or older. Use of a mathematical method to correct the reported number of pertussis patients per 100,000 population with a constant obtained from analysis of the reported number of exanthem subitum cases allowed us to compare the number of pertussis patients in the three areas with each other. Vaccination rate by age and incidence of pertussis in each city revealed the efficacy of acellular pertussis vaccine to be 94.8%.

Age Factors↗
PubMed1991

[Clinical significance of thrombocytopenia associated with hemorrhagic cerebrovascular diseases].

We investigated the clinical significance of thrombocytopenia (platelet counts less than 10 x 10(4)/mm3) associated with hemorrhagic cerebrovascular disease. This study was conducted in 96 patients suffering from hemorrhagic cerebrovascular diseases. We divided the clinical course into 3 stages: acute (from the 1st to 7th day), subacute (8th-21st day) and chronic (after the 22nd day). The average age of the patients with thrombocytopenia (TCP) was 60.6 years old. TCP was more frequent in men (81.3%) than in women (18.7%). TCP developed in 18.6% (8/43) of patients with subarachnoid hemorrhage (SAH) and in 15.1% (8/53) of those with intracerebral hemorrhage (ICH). Among the patients with SAH, four were in the acute stage, three in the subacute stage and two in the chronic stage. TCP due to SAH was more likely to develop in the acute and/or subacute stage. TCP due to SAH showed two peak appearances: the first was within 24 hours (n = 3), and the second was around 10 days after onset (n = 3). The cause of TCP in its late peak appearance was presumed to be the consumption of platelets due to microembolism induced by vasospasm and/or hemodilution therapy. Among patients with ICH, five cases were in the acute stage, three in the subacute stage and two in the chronic stage. TCP due to ICH was more likely to develop in the acute stage. Fifty percent (4/8) of the patients with ICH had TCP on admission. This data suggested that TCP was possibly a cause or an inducer for ICH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Effectiveness of periodic checkup by ultrasonography for the early diagnosis of hepatocellular carcinoma.

Periodic checkup by ultrasonography was conducted on patients with chronic liver diseases for early detection of hepatocellular carcinoma. In 19 months, a total of 2004 examinations were performed on a total of 660 cases (179 cases with liver cirrhosis in the compensatory stage, younger than 70 years; 481 cases with chronic hepatitis, aged 40 to 70 years for men and 50 to 70 years for women). Of the 660 cases, 22 HCC cases (3.3%) were detected and finally diagnosed by angiography and/or histologic examination. Four of those cases (18%) had a single nodule smaller than 1 cm in diameter, and 11 cases (50%) had a single nodule smaller than 2 cm. Surgical resection was performed on 12 cases (55%). In comparison with the control group (83 HCC cases not receiving any periodic checkup), the frequency of small liver cancer and the surgical resection rate in the study group were significantly higher. This examination system by periodic ultrasonography checkup of patients with chronic hepatic diseases was effective for early detection and permitted aggressive therapy of hepatocellular carcinoma.

Adult↗
PubMed1990

Medullary carcinoma with lymphocytic infiltration of the stomach. Clinicopathologic study of 27 cases and immunohistochemical analysis of the subpopulations of infiltrating lymphocytes in the tumor.

The current study attempts to clarify the possible immune response that occurs in medullary carcinoma with lymphocytic infiltration of the stomach by an immunohistochemical analysis of the subpopulations of tumor-infiltrating lymphocytes. This carcinoma was histologically characterized by the sparse population of small nests consisting of poorly differentiated carcinoma cells, widely separated by intervening nondesmoplastic stroma infiltrated uniformly with abundant lymphocytes frequently accompanied by lymph follicles. An immunohistochemical analysis revealed that T-cells were evenly distributed throughout the tumor with intimate contact with individual carcinoma cells, except the lymph follicles consisted mainly of B-cells. Because of the similarities of morphologic features and subpopulations of tumor-infiltrating lymphocytes of this carcinoma to the normal lymphoid tissue, an organized immune response combined with cell-mediated and humoral immunities against the invading carcinoma cells seemed to occur in this type of gastric carcinoma, resulting in a excellent prognosis compared with that in ordinary gastric carcinoma.

Adult↗
PubMed1990

Effect of intermittent infusions of somatostatin on growth hormone secretion in unrestrained male rats with hypothalamic deafferentation.

The effect of intermittent infusions of somatostatin (SS) on growth hormone (GH) secretion was studied in unrestrained adult male rats deprived largely of SS influence on the medial basal hypothalamus by anterolateral deafferentation (AL-cut). In addition, the influence of hypothalamic surgery on the plasma GH response to beta-endorphin (beta-END) was observed. In sham-operated rats, high-amplitude GH pulses separated by low baseline levels occurred at 185 min intervals. In rats with AL-cut, GH pulses were difficult to identify upon visual appraisal and baseline plasma GH levels became significantly higher than those of sham-operated rats. When AL-cut was performed unilaterally (half-AL-cut), low amplitude GH pulses separated by elevated baseline GH levels occurred at frequent intervals. The amount of GH secreted during 6 h was significantly reduced in rats with AL-cut or half-AL-cut as compared to that of sham-operated rats. The plasma GH response to intracerebroventricular injection of beta-END (4 micrograms) was abolished in AL-cut rats, and the response was significantly reduced in half-AL-cut rats as compared to that of sham-operated rats. When AL-cut rats were subjected to repeated infusions of SS (30 micrograms/kg b. wt./h, 150 min) separated by 30 min control periods, a large rebound of GH secretion was observed after removal and the amount of GH secreted during 6 h became comparable to that of sham-operated rats. The results suggest that SS plays important roles in the dynamic secretion of GH.

Animals↗
PubMed1990

Serial quantitative image analysis and confocal microscopy of hepatic uptake, intracellular distribution and biliary secretion of a fluorescent bile acid analog in rat hepatocyte doublets.

To characterize the poorly understood mechanisms of intracellular transport of bile acids, fluorescein isothiocyanate-glycocholate was synthesized and its ring-OH-linked structure established by fast atom bombardment, mass spectroscopy and 13C nuclear magnetic resonance. Biliary secretion of fluorescein isothiocyanate-glycocholate and [14C]-labeled glycocholate in rats was similar, in contrast to the biliary secretion of sodium fluorescein and methylamine-conjugated fluorescein isothiocyanate, which are non-bile acid organic anions. After incubation of cultured hepatocyte doublets with fluorescein isothiocyanate-glycocholate, serial quantitative image analysis of fluorescence was performed in the cellular cytoplasm, perinuclear zone and bile canaliculus. Uptake of fluorescein isothiocyanate-glycocholate into the cytoplasm was inhibited by removal of sodium from the medium and by addition of glycocholate or taurocholate. After preincubation with colchicine, but not lumicolchicine, the proportion of perinuclear to cytoplasmic fluorescein isothiocyanate-glycocholate increased during incubation with fluorescein isothiocyanate-glycocholate. Neither fluorescein isothiocyanate-glycocholate uptake nor canalicular secretion was affected. By confocal microscopy the perinuclear zone containing fluorescein isothiocyanate-glycocholate was identified as the Golgi apparatus by fluorescent colocalization with C6-NBD-ceramide, which specifically identifies the Golgi apparatus. We conclude that colchicine inhibits fluorescein isothiocyanate-glycocholate transfer from the Golgi apparatus to the bile canaliculus. These results suggest that intracellular bile acid transport involves microtubule-dependent vesicular movement from the Golgi apparatus to the bile canaliculus. The role of this process in normal physiology is uncertain.

Animals↗
PubMed1990

Specific enzyme immunoassay for alpha-fetoprotein from hepatocellular carcinoma.

alpha-Fetoprotein in sera from healthy subjects and patients with liver cirrhosis and hepatocellular carcinoma was fractionated into three peaks by affinity chromatography on a column of Lens culinaris agglutinin-Sepharose 4B. One peak (the first peak) was found in all the serum samples, but the other two peaks (the second and third peaks) were found only in patients with hepatocellular carcinoma. For alpha-fetoprotein in the second and third peaks, a specific enzyme immunoassay was developed. Lens culinaris agglutinin-coated polystyrene balls were incubated with alpha-fetoprotein and, after washing, with affinity-purified anti-alpha-fetoprotein Fab'-beta-D-galactosidase conjugate. beta-D-galactosidase activity bound to the polystyrene balls was assayed by fluorimetry. The maximal volume of serum that could be used without interference was 0.2 microliters, and the minimal detectable serum concentrations of alpha-fetoprotein in the second and third peaks were 3.5 mg/liter and 0.1 mg/liter, respectively. The maximal serum concentration of alpha-fetoprotein in the first peak that did not affect the detection limits of alpha-fetoprotein in the second and third peaks was 10 mg/liter. It was possible to confirm the presence of alpha-fetoprotein in the second and third peaks by a significant difference between bound beta-D-galactosidase activities in the absence and presence of alpha-methyl-D-mannoside or D-glucose. This assay may be useful for diagnosis of hepatocellular carcinoma, although further improvements remain to be made.

Carcinoma, Hepatocellular↗
PubMed1990

Novel and sensitive enzyme immunoassay (immune-complex-transfer enzyme immunoassay) for alpha-fetoprotein from hepatocellular carcinoma.

Alpha-fetoprotein in sera from patients with hepatocellular carcinoma was fractionated into three peaks by affinity chromatography on a column of Lens culinaris agglutinin-Sepharose 4B. One peak (the first peak), which passed through the column without adsorption, was found in both healthy subjects and patients with liver cirrhosis and hepatocellular carcinoma. The second and third peaks were reactive with L. culinaris agglutinin and found only in patients with hepatocellular carcinoma. For alpha-fetoprotein in the second and third peaks, a novel and sensitive enzyme immunoassay (immune-complex-transfer enzyme immunoassay) was developed. Alpha-fetoprotein in test serum was reacted with dinitrophenyl affinity-purified anti-alpha-fetoprotein IgG, and the complex formed was trapped onto affinity-purified (antidinitrophenyl bovine serum albumin) IgG-coated polystyrene balls. The polystyrene balls were washed to eliminate substance(s) other than alpha-fetoprotein in the test serum, and the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine. The eluted complex containing alpha-fetoprotein in the second and third peaks was trapped onto L. culinaris agglutinin-coated polystyrene balls and reacted with affinity-purified anti-alpha-fetoprotein Fab'-beta-D-galactosidase conjugate. Beta-D-galactosidase activity bound to the polystyrene balls was assayed by fluorimetry. The maximal volume of serum that could be used without interference was 20 microliters, which was 100-fold larger than that in the previous enzyme immunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers, Tumor↗