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Biomedical subjects

T Mizokami

Publications and source records attributed to T Mizokami.

At least 19 recordsLinked to original sources
PubMed1992

Preserved thyroidal secretion of thyroxine in acromegalic patients with suppressed hypophyseal secretion of thyrotrophin.

OBJECTIVE: We have assessed the mechanisms which maintain euthyroidism in acromegalic patients despite the suppression of thyrotrophin (TSH) secretion. MATERIALS: Fourteen untreated patients with acromegaly were analysed. Ten patients were also studied after pituitary surgery. METHODS: Thyroid hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and thyroidal uptake of radioactive iodine, thyrotrophin releasing hormone (TRH) test and basal metabolic rate (BMR) were measured before and after pituitary surgery. RESULTS: Nine patients had palpable goitres. The TSH response to TRH stimulation was suppressed in eight patients, who maintained normal serum levels of total T3, T4 and free T4. The patients with normal TSH response had lower levels of free and total T4 than controls. The response of TSH to TRH correlated inversely with the serum level of total and free T4, and also with the plasma level of IGF-I (r = -0.74, P less than 0.05, n = 9). After pituitary surgery, the serum levels of total and free T4 were elevated for at least up to 6 months, with a decrease in the T3/T4 ratio and the BMR. CONCLUSION: GH may have a direct stimulatory action on the thyroid secretion of T4 possibly via increased IGF-I, despite suppressed TSH secretion. The post-operative elevation of serum T4 suggests the persistent secretion of T4 from the thyroid gland, in spite of instantaneous normalization of the accelerated conversion of T4 to T3, even after reduction of excess GH secretion.

Acromegaly↗
PubMed1992

Effect of captopril on isoproterenol-induced cardiac hypertrophy and polyamine contents.

It is well known that isoproterenol (ISO) a nonselective beta adrenoceptor agonist induces cardiac hypertrophy. It can be assumed that, in addition to its direct cardiac effect, ISO has a cardiac trophic effect via stimulation of the renin angiotensin system. Synthesis of polyamines is facilitated in cardiac hypertrophy and polyamine levels are rapidly elevated prior to an increase in heart weight. In the present study, we investigated whether captopril (30 mg/kg body weight, daily) could attenuate cardiac hypertrophy and elevation of cardiac polyamine levels in rats, which effects were elicited by a chronic (1- or 2-weeks) and repeated administration of a small dose (0.5 mg/kg body weight) of ISO. Cardiac hypertrophy was assessed by an increase in the wet weight and RNA content of the heart. Polyamines were analyzed by HPLC. Captopril alone did not affect either heart weight/body weight ratio or cardiac contents of polyamines and nucleic acids at the end of the second week. In isoproterenol-treated rats, the above parameters, except for putrescine content on day 14, were significantly increased on both day 7 and day 14. Captopril slightly attenuated ISO-induced cardiac hypertrophy and significantly prevented the ISO-evoked increase in the contents of RNA, spermidine, and spermine at the end of the second week. These results suggest that the ISO-evoked increase in cardiac polyamines was mediated, at least in part, by the renin angiotensin system, which was stimulated by ISO.

Animals↗
PubMed1992

Reversible primary hypothyroidism and elevated serum iodine level in patients with renal dysfunction.

Recovery of thyroid function in patients with both thyroid and renal dysfunction was studied. Among 245 patients with primary hypothyroidism (serum TSH greater than 10 mU/l), 36 had mild to severe renal dysfunction (serum urea nitrogen greater than 7.1 mmol/l and creatinine greater than 106 mumol/l). Of these 36 patients, recovery of the thyroid function after iodine restriction was observed in 30 (83%), in whom an elevated serum non-hormonal iodine level (median 236, range 67-15,591 micrograms/l, N = 19) and a high thyroidal radioactive iodine uptake (51.5 +/- 29.3% at 24 h, N = 26) were observed. The perchlorate discharge test was positive in 7 of 13 patients examined, suggesting an iodide organification defect rather than an atrophic or destructive change in the thyroid. Antithyroid antibodies were negative in 22 patients (73%) and an almost normal thyroid gland or colloid goitre was confirmed histologically in 8 of them. After a 13.2 mg potassium iodide loading test, 24 h urinary excretion of iodine was about 60% in normal controls, but only 10% in a different group of six euthyroid patients with renal dysfunction. These findings suggest that impaired renal handling of iodine rather than autoimmune mechanism may have a significant role in the pathogenesis of reversible hypothyroidism found in patients with renal dysfunction, probably through a prolonged Wolff-Chaikoff effect.

Adult↗
PubMed1991

Effect of captopril on isoproterenol-induced myocardial ornithine decarboxylase activity.

Polyamines are thought to play an essential role in cellular hypertrophy and proliferation. Ornithine decarboxylase (ODC) catalyzes the first and probably the rate-limiting step in biosynthesis of polyamines. In this study, we evaluated the pathophysiological role of the renin-angiotensin system in isoproterenol-induced cardiac hypertrophy, using myocardial ODC activity as an indicator of cardiac hypertrophy. Isoproterenol caused an eight-fold increase of myocardial ODC activity in normotensive Wistar rats within 4 h after injection. Captopril suppressed the induction of ODC by isoproterenol to two-thirds of the control level. These results indicate that the renin-angiotensin system may participate in the induction of myocardial hypertrophy by isoproterenol.

Animals↗
PubMed1991

Mandibular alveolar ridge extension method using a surgical splint with porous hydroxyapatite (HAP) particles.

The mandibular alveolar ridge extension method is a surgical technique to extend the alveolar ridge up to the required level. Using a surgical splint prepared to meet the clinical requirements establishes the desirable alveolar ridge extension with porous hydroxyapatite (HAP) particles. Before the operation, a working cast of the extremely resorpted mandibular alveolar ridge is remodeled into its desired shape with paraffin wax, and the extended surgical splint is cured by clear acrylic resin. After subperiosteal tunnel dissection, the surgical splint is fixed to the mandible with circummandibular ligatures; then the HAP particles are injected into the tunnel. After healing, a treatment denture is cured between the artificial dentition and the surgical splint with self curing resin. In this method, the HAP particles are injected into the subperiosteal tunnel that is created between the surface of alveolar bone and the periosteum covered by the surgical splint; the migration of HAP particles completes the extension of the alveoral ridge.

Alveolar Ridge Augmentation↗
PubMed1990

New screening system for unruptured cerebral aneurysms--combination of an expert system and DSA examination.

We have designed a screening system to diagnose unruptured aneurysms, including the use of digital subtraction angiography (DSA). We surveyed 115 patients who had undergone clipping procedures after subarachnoid hemorrhage (SAH) and questioned them with regard to the subjective symptoms. Sixty-eight of 92 patients who returned the questionnaire reported, prior to rupture, headache, eye pain, and neck pain most frequently, and also impairment of extraocular movements, ptosis, visual field defects, and motor and sensory disturbances. Nineteen (47.5%) of 40 patients who had complete pain relief after surgery complained of headache from 1 week to 1 month before SAH. In addition, nine patients (22.5%) complained of headache for several years, and were also pain-free after surgery. For the indication of DSA, we employed an expert system based on fuzzy set theory. Seven groups of parameters are: Group 1, a basic questionnaire concerning age, sex, and past and family histories; Group 2, 15 warning signs selected on the basis of retrospective study; and Groups 3-7, detailed questions concerning each sign. Scoring weights assigned to each condition based on the results of the retrospective study, and threshold values were determined by several neurosurgeons. The certainty factors for intermediate hypotheses were calculated from these weights and threshold values and summed up, from which the conclusion was obtained. Twelve new cases of unruptured cerebral aneurysm were diagnosed using this screening system. This system may improve the ability to diagnose cerebral aneurysms before rupture.

Aged↗
PubMed1978

Posttraumatic epilepsy and CT scan.

Among 83 head-trauma cases examined by CT scan in a later year, 41 were included in a seizure group of those who clinically showed late epilepsy and who obviously showed epileptic discharge such as spike or spike and wave in EEG after trauma, and 42 were included in a nonseizure group of those who had some sequelae such as abnormal findings in EEG or neurologic defects: the CT findings of these 83 cases were collected and compared with clinical findings, EEG, and other data. The CT findings of these cases were divided into five groups: (A) a normal group; (B) a group showing partial or unilateral ventricular dilatation; (C) a group showing porencephaly in the cerebral parenchyma; (D) a group suspected of cortical atrophy; (E) a group of other cases. Group D contained 44.3% of the cases, and was the largest group; the frequency of seizure was highest in Group C. The CT classification reveals the contradiction of the conventional definition of posttraumatic epilepsy and also poses some problems concerning the disease. CT scan is mostly applied to head trauma in the acute stage, and as for trauma in the chronic stage there are a few reports on chronic subdural hematoma and post-traumatic hydrocephalus. We noticed posttraumatic epilepsy among the sequelae of trauma, and then analyzed CT findings of the epilepsy: the results are reported here.

Adolescent↗