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Biomedical subjects

T Mitsuma

Publications and source records attributed to T Mitsuma.

389 records · Page 22Linked to original sources
PubMed1971

Serum triiodothyronine: measurements in human serum by radioimmunoassay with corroboration by gas-liquid chromatography.

Serum triiodothyronine (T(3)) has been measured by radioimmunoassay and corroborated by analysis of the identical samples with a previously described gas-liquid chromatographic technique. Special features of the radioimmunoassay procedure which permit determinations in unextracted serum include the use of a T(3)-free serum preparation for the construction of the standard curve and of tetrachlorothyronine to inhibit binding of T(3) to thyroxine-binding globulin.T(3) values by radioimmunoassay were 138 +/-23 ng/100 ml (mean +/-SD) in 82 normal subjects, 62 +/-9 ng/100 ml in 45 hypothyroid patients, and 494 +/-265 ng/100 ml in 60 patients with toxic diffuse goiter. In the hypothyroid group, the range was similar in patients with both primary and secondary hypothyroidism. There was no overlap between the three thyroidal states. Elevated T(3) levels were seen in 40 cases that appeared clinically hyperthyroid but had normal serum thyroxine (T(3)) determinations, a syndrome we have called T(3) toxicosis. Values obtained with radioimmunoassay agreed closely with those we had previously found by gas-liquid chromatography which were 68 +/-2 ng/100 ml in hypothyroidism, 137 +/-23 ng/100 ml in normal subjects, and 510 +/-131 ng/100 ml in untreated toxic diffuse goiter. Since T(3) is very potent and its level varies in different clinical states, accurate T(3) measurements are required to assess a patient's thyroid status properly. The radioimmunoassay for T(3) appears to be sufficiently sensitive, precise, and simple to permit its routine clinical application for this purpose.

Animals↗
PubMedDate not supplied

Effects of histamine and related compounds on the release of immunoreactive thyrotropin-releasing hormone from the rat stomach in vitro.

Effects of histamine and related compounds on the release of immunoreactive thyrotropin-releasing hormone (ir-TRH) from the rat stomach in vitro were studied. The rat stomach was incubated in medium 199 with 1.0 mg/ml of bacitracin and 100 micrograms/ml of ascorbic acid (pH 7.4) for 20 min. The amount of TRH release into the medium was measured by radioimmunoassay. The ir-TRH release from the rat stomach was enhanced significantly in a dose-related manner with the addition of histamine and inhibited with the addition of famotidine, but not with mepyramine. The stimulatory effect of histamine on ir-TRH release from the stomach was partially blocked with the addition of famotidine, but not with mepyramine. The elution profile of acid-methanol-extracted rat stomach on Sephadex G-10 was identical to that of synthetic TRH. These findings suggest that histamine stimulated ir-TRH release from the rat stomach in vitro, and that histamine's effects may be mediated via a H2-receptor.

Animals↗
PubMedDate not supplied

Geometric response to nerve growth factor is preserved in aged rat sensory neurons: a single-neuron culture study.

We previously established a single-neuron culture system to analyze the primary effects of neurotrophic factors and reported that NGF promoted neurite extension in young adult (4- to 6-month-old) rat dorsal root ganglion (DRG) neurons by promoting neurite arborization. In this study, we demonstrated that the effects of NGF on neurite regeneration in DRG neurons was well preserved in aged rats (20- to 24-month-old and 33-month-old). NGF did not increase the percent process-bearing neurons in aged rats, which indicated that neuronal survival was not promoted by NGF, but it significantly enhanced the number of branching points, total neurite length, and soma size in aged neurons. These effects of NGF on neurite geometry tended to be reduced to some extent in aged neurons and the initiation of neurite-outgrowth in aged neurons was also delayed as compared with young adult neurons. NGF-responsive subpopulation of neurons, found in the entire range of neuronal size, were preserved in aged rats. These findings indicate that NGF could play an important role in regeneration of injured DRG neurons of aged animals.

Aging↗
PubMedDate not supplied

Measurements of free and total serum T3 and T4 in pregnant subjects and in neonates.

Despite recent descriptions of dramatic changes in the thyroidal economy in pregnancy, the precise mechanisms of these alterations have remained obscure. Measurements of total and free triiodothyronine (T3) and thyroxine (T4) and thyroxine binding capacity (TBG) were made in 120 serum samples from 42 first trimester, 55 second trimester, and 23 third trimester pregnant women. Sixteen paired term and cord blood samples were also analyzed. Mean total serum T4 rose progressively from 9.8 in the first trimester to 11.5 mug/100 ml in the third trimester. Mean TBG capacity also increased from 38.4, first trimester, to 56.2 mug/100 ml in the third trimester. Mean total T3 concentrations were significantly elevated in all trimesters (p less than 0.02 - 0.0011) when compared to normal nonpregnant controls. Total T3, T4 and TBG levels were all significantly higher than in normal nonpregnant women in all trimesters (p less than 0.001). TSH levels remained unchanged in all three trimesters; values were 2.2, 2.0, and 2.0 muU/ml, respectively. Free T4 levels were at the lower limits (2.4, 2.5, and 2.2 ng/100 ml) and free T3 levels were below normal (0.29, 0.27, and 0.24 ng/100 ml). In addition, fetal T3 concentrations were strikingly lower in cord blood than in the maternal circulation at term. Maternal and cord free T3 and free T4 levels were not significantly different. These data underscore the need for multiple measurements of thyroid function in pregnancy and in the newborn in the evaluation of the thyroid gland activity.

Female↗
PubMedDate not supplied

Concentrations of immunoreactive thyrotropin-releasing hormone in spinal cord of patients with amyotrophic lateral sclerosis.

Concentrations of immunoreactive thyrotropin-releasing hormone (ir-TRH) were measured by specific radioimmunoassay in the spinal cord of six patients with amyotrophic lateral sclerosis (ALS) and seven with non-neurological diseases. Ir-TRH concentrations were the highest in the anterior horn, compared with other areas of the spinal cord, both in non-neurological diseases and ALS. Ir-TRH concentrations in the anterior horn of ALS were significantly lower than in non-neurological diseases, but were the same in both groups in other parts of the spinal cord (e.g. posterior horn, frontal part, lateral and central part, posterior part). Ir-TRH concentrations in rat spinal cords were stable for up to seven hours when spinal cord was stored after death at 4 degrees C or 22 degrees C. An elution profile of methanol-extracted human spinal cord on Sephandex G-10 column was identical to that of synthetic TRH. The cell population in the anterior horn in ALS was decreased markedly. The findings suggest that TRH is present in the human spinal cord and its decreased concentrations in the anterior horn of ALS may be due to a decrease in the cell population.

Amyotrophic Lateral Sclerosis↗
PubMedDate not supplied

Immunoreactive-somatostatin concentrations of the human stomach and mood state in patients with functional dyspepsia: a preliminary case-control study.

Immunoreactive-somatostatin (ir-SS) concentrations of the gastric mucosa and mood state in patients with functional dyspepsia were examined. The subjects were 12 patients with upper abdominal discomfort, nausea and/or vomiting (motility disorder group) and 14 patients complaining of upper abdominal pain (ulcer-like disorder group) for more than a month without any organic upper-gastrointestinal tract disease proven by endoscopy. These patients were compared with either an age- and sex-matched group of asymptomatic outpatients without any organic disease (control group: n = 26) or to a group of patients with peptic ulcer (n = 19). Somatostatin concentrations of the stomach were measured by radio-immunoassay, and the mood state of each subject was assessed by Manifest Anxiety Scale (MAS) and Self-rating Depression Scale test. Immunoreactive-somatostatin concentrations of the gastric mucosa were significantly higher in the ulcer-like disorder group than in the peptic ulcer, motility disorder or control group, and gastric juice levels were higher in the ulcer-like disorder group. The psychometric tests showed that the motility disorder group was more depressive than the ulcer-like disorder group, but there were no differences between the motility disorder, ulcer-like disorder and peptic ulcer group in MAS scores or environmental factors. These results indicate that there may be two different subgroups in functional dyspepsia influenced by both ir-SS concentration of the stomach and/or mood state.

Adult↗
PubMedDate not supplied

Effect of histamine on thyrotropin-releasing hormone and somatostatin secretion in rat stomach.

BACKGROUND/AIMS: Histamine plays an important role in gastric function, and the histaminergic system is involved in the regulation of neuropeptides and gastric acid secretion. METHODOLOGY: We investigated the effect of histamine and histamine receptor antagonist (HRA) on the intraluminal secretion of thyrotropin-releasing hormone (TRH) and somatostatin (SOM) using a rat luminal perfusion model. RESULTS: Intravenous administration of histamine caused an increase in TRH secretion and a decrease in SOM secretion preceding a decrease in pH in the perfusate. When the total contents of TRH and SOM in the perfusate were calculated after administration of histamine, the effect of histamine was found to be dose-dependent in both neuropeptide secretions. Under basal conditions, neither H1RA, H2RA, nor H3RA caused changes in TRH secretion into the perfusate. In contrast, H2RA and H3RA yielded an increase in basal SOM secretion. When administered before the injection of histamine, H2RA caused a complete inhibition of histamine-induced changes in TRH and SOM secretion. Preadministration of H3RA also induced a weak but significant inhibition of the changes in neuropeptide secretion. CONCLUSION: It was concluded that paracrine pathways do exist among histamine, TRH, and SOM in the regulation of gastric acid secretion.

Animals↗