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Biomedical subjects

K Uchida

Publications and source records attributed to K Uchida.

At least 1,099 records · Page 61Linked to original sources
PubMed1990

Occlusal force distribution in lower complete overdentures.

A space between the denture base and a root cap can effectively control the distribution ratio of occlusal force to abutment teeth and an alveolar ridge. The purpose of this study on abutments was to analyse the effect of variation in space (0 mm (no space), 0.3 mm and 0.6 mm) on the above ratio. Six subjects, 38-65 years of age, each with an edentulous maxilla and several teeth remaining in the mandible, were selected for this experiment. The lower experimental denture had embedded a transducer which could detect a change in the vertical force applied to the experimental tooth. This transducer was capable of changing the vertical space between a denture base and an experimental tooth. Each subject was asked to increase the occlusal force applied to the denture from zero to the maximum loading rate of 5 kgf s-1. The occlusal force and the force exerted on the experimental tooth were recorded in each space 1 month after insertion of new dentures. The following results were obtained: (i) when the occlusal force was applied to the artificial tooth just above the abutment tooth, the mean ratio in the 0 mm space was 60% of the force applied to the denture, the ratio in the 0.3 mm space was 50%, and the ratio in the 0.6 mm space was 30%; (ii) if the occlusal force was applied to the point 10 mm distant from the point just above the experimental tooth, the magnitude of the ratio was decreased by 60-80%.

Adult↗
PubMed1990

Carmofur-induced organic mental disorders.

Organic mental disorder was observed in a 29-year-old female in the prognostic period after the onset of carmofur-induced leukoencephalopathy. Symptoms such as euphoria, emotional lability and puerile attitude noted in the patient were diagnosed as organic personality syndrome according to the criteria defined in the DSM-III-R. It is referred to as a frontal lobe syndrome. Brain CT revealed a periventricular low density area in the frontal white matter and moderate dilatation of the lateral ventricles especially at the bilateral anterior horns. Consequently, carmofur-induced leukoencephalopathy may uncommonly result in organic personality syndrome in the residual state. It may be attributed to the structural damage to the frontal lobe.

Adenocarcinoma↗
PubMed1990

Estimation of growth fraction in situ in human bladder cancer with bromodeoxyuridine labelling.

A group of 8 patients with invasive bladder cancer received fractionated intra-arterial infusions of the thymidine analogue bromodeoxyuridine (BrdU), 150 mg, every 6 to 10 h for 3 days before endoscopic cold cup biopsy to label tumour cells in the proliferative pool (growth fraction). The tumour specimens were fixed and stained by an indirect immunoperoxidase method using anti-BrdU monoclonal antibody. There was an area which could not be stained with anti-BrdU monoclonal antibody surrounding the stained area where diffusion effects could be excluded. This indicates a growth fraction less than 1 and implies that a proportion of the tumour cells in bladder tumours are cycling and contributing to growth. The BrdU labelling index (growth fraction) was determined by counting the number of BrdU labelled cells in the well labelled tissue sections. The average growth fraction of invasive bladder cancer was 38.4 +/- 7.7% (range 26.9-48.1%). Grade 3 tumours averaged 42.8 +/- 5.4% labelling versus 31.0 +/- 4.4% in grade 2. The higher growth fraction may indicate greater biological malignancy. These results indicate that immunohistochemical studies of cell kinetics using BrdU monoclonal antibodies may provide information about the biological characteristics of bladder tumours in situ.

Aged↗
PubMed1990

Disruption of microtubules as an early sign of irreversible ischemic injury. Immunohistochemical study of in situ canine hearts.

Structural disruption of the cytoskeleton may be involved in irreversible ischemic injury. In the present study, ischemic changes in microtubules during various periods of myocardial ischemia were studied with an immunohistochemical technique in open-chest dogs. In intact myocardium, microtubules were stained as a filamentous network throughout cytoplasm and a circular network around the nucleus, which disappeared with colchicine treatment. In brief ischemia of less than 15 minutes, microtubule patterns were unaltered. After 20 minutes, however, characteristic microtubule stains were partly lost in patchy lesions. As an increase in ischemic period, lesions of loss of microtubule stains were increased in number and size. After 120 minutes of reperfusion following 60 minutes of ischemia, the lesions with intact actin filaments but with disrupted microtubules were replaced by the severely injured cells in which the regular myofibrillar registrations were distinctly disrupted. After 24 hours of reperfusion following 40 minutes of occlusion of the left circumflex artery, the percent area of disrupted microtubules at 40 minutes of ischemia was replaced by that of irreversibly injured lesions in the posterior papillary muscle. These results indicate that disruption of microtubules during ischemia heralds irreversible ischemic injury. However, in in vitro study, the myocardium incubated in hypoxic solution for 60-120 minutes demonstrated earlier disruption of the microtubules than the vinculin. Electron microscopic study also showed minimal irreversible changes in the lesions with disrupted microtubules. Thus, taken together, we conclude that microtubules that support the structural integration of myofibrils and other organelles are disrupted in severe myocardial ischemia before the irreversible injury, promoting the irreversible change after reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of repetitive administration of corticotropin-releasing hormone combined with lysine vasopressin on plasma adrenocorticotropin and cortisol levels in secondary adrenocortical insufficiency.

To examine the functioning of the hypothalamo-pituitary-adrenocortical axis in secondary adrenocortical insufficiency, we administered 100 micrograms synthetic human CRH, iv, plus 10 U lysine-8-vasopressin (LVP), im, three times daily for 3 consecutive days. The changes in plasma ACTH and cortisol levels during the administration and the response to an insulin tolerance test (ITT) conducted before and after the administration were determined. In three patients with isolated ACTH deficiency, basal plasma ACTH and cortisol levels were undetectablly low, and there was no response noted in the ITT or during CRH-LVP administration throughout the observation period. In four patients with adrenocortical insufficiency who had undergone successful transsphenoidal microadenomectomy for Cushing's disease and in six patients who had undergone curative unilateral adrenalectomy for Cushing's syndrome, basal plasma ACTH levels were low, but responded considerably to both stimulation tests. Along with the 3 days of CRH-LVP stimulation, however, neither the peak nor the time-integrated ACTH response was significantly enhanced, because of the variability of the responses among the patients. Compared with the ACTH response on the last day of CRH-LVP stimulation, the subsequent ITT tended to induce a lower ACTH response in the post-Cushing's disease patients and a higher response in the post-Cushing's syndrome patients. Regarding the plasma cortisol levels, the basal, peak, and integrated responses tended to increase daily during CRH-LVP administration. Conversely, the ITT after repetitive CRH-LVP administration induced a higher cortisol response than the test before CRH-LVP administration in the post-Cushing's disease patients. No serious complications were noted in any of the patients during or after the treatment. The present findings indicate that 1) repetitive administration of CRH in combination with LVP is a safe and valuable provocation test to examine the pituitary ACTH reserve and the integrity of the pituitary-adrenocortical axis; 2) isolated ACTH deficiency is usually due to a defect at the pituitary level; 3) with respect to adrenocortical responsiveness, post-Cushing's disease patients show a better accumulation of the provocative effect than do post-Cushing's syndrome patients; and 4) both hypothalamic and pituitary dysfunction are responsible for adrenal hypofunction in patients after hypercortisolemia, but post-Cushing's syndrome patients (especially those with a short period of hypercortisolemia) appeared to have less impairment of hypothalamic ACTH-releasing activity than post-Cushing's disease patients.

Adrenal Cortex↗
PubMed1990

Antiviral agents of plant origin. II. Antiviral activity of scopadulcic acid B derivatives.

Scopadulcic acid B derivatives were synthesized and their antiviral activities against herpes simplex virus type 1 (HSV-1) were examined. All the derivatives synthesized showed lower inhibitory activities against HSV-1 than scopadulcic acid B (2). Five compounds, 7, 8, 15, 16, and 18, however, had in vitro therapeutic indexes larger than 7 and were considered to merit further investigation.

Antiviral Agents↗
PubMed1990

[Effect of cefaclor on guinea pig platelet aggregation in vitro].

Effects of cefaclor (3-chloro-7-D-(2-phenyl-glycinamido)-3-cephem-4-carboxylic acid) on PAF, ADP, collagen, endotoxin, and thrombin-induced platelet aggregation were examined in vitro with the use of guinea pig platelet-rich plasma and washed platelets. PAF, even at concentrations lower than its minimum effective concentration, enhanced ADP- or endotoxin-induced platelet aggregation and prolonged the time to attain the maximum aggregation. PAF also enhanced collagen-induced platelet aggregation and shortened the lag time. Cefaclor (CCL) inhibited the PAF, ADP or thrombin induced platelet aggregation and shortened their maximum aggregation times at higher concentrations such as 300 micrograms/ml or more. CCL also inhibited the collagen-induced platelet aggregation and prolonged the lag time, but showed no effect on endotoxin-induced platelet aggregation. The effect of CCL was almost the same as that of latamoxef (LMOX). CCL and LMOX, however, showed no effect on cellular Ca2+ increase produced by PAF, ADP, or thrombin, suggesting that the inhibitory effect of CCL and LMOX on platelet aggregation is caused by the inhibition of fibrinogen binding to the glycoprotein IIb/IIIa complex.

Adenosine Diphosphate↗
PubMed1990

Identification of staphylococci from bovine mastitis and an examination of their susceptibility to antibiotics and beta-lactamase production.

Strains of Staphylococcus species isolated from bovine mastitic milk at 66 dairy farms in Japan during the period from November 1988 to May 1989 were identified, and examined for their drug susceptibility and beta-lactamase production in order to clarify an epidemiological aspect of bovine mastitis caused by staphylococci. The results of bacteriological identification showed that the most predominant species was S. xylosus. Other major species isolated were S. aureus, S. sciuri and S. hyicus. Thirty-eight (71.7%) isolates of S. xylosus, 21 (45.7%) of S. aureus and 5 (71.4%) of S. epidermidis were positive for beta-lactamase production. Most of the beta-lactamase-producers of S. aureus were classified as high producers, although all of the beta-lactamase-positive S. xylosus isolates remained to be low producers. All isolates of S. aureus were sensitive to methicillin and cloxacillin at 6.25 micrograms/ml and 1.56 micrograms/ml, respectively, and none of methicillin-resistant S. aureus were detected. Isolates of other species were considered to be susceptible to 6 beta-lactams, in contrast to human isolates, but antibacterial activities of penicillin G and ampicillin were affected more strongly by beta-lactamase than those of methicillin, cloxacillin, cefazolin and cefoperazone.

Animals↗
PubMed1990

Amyloid angiopathy with cerebral hemorrhage and senile plaque in aged dogs.

Amyloid angiopathy with cerebral hemorrhage and senile plaques was found in the brain of aged dogs. In all 9 cases examined, 13 to 19 years old, 6 males and 3 females, amyloid deposits were observed mostly in the wall of cerebral arterioles and capillaries showed hyaline degeneration. The accumulation of amyloid fibrils measuring about 10 nm in diameter was seen in the cerebral vessel wall by electron microscopy. The cerebral hemorrhage was observed in 6 of 9 dogs and 2 of them showed massive hemorrhage. The hemorrhagic foci were sometimes closely contact with the vessels involved in amyloid angiopathy. In addition, senile plaques being classified into 2 types were found in the cerebral cortex of 3 dogs. The first type was characterized by the accumulation of degenerative neurites and often contained granular argyrophilic material. The second type had a well-defined amyloid core with neuritic halo. Amyloid deposits were also found in or around intestinal vessel walls of 3 dogs. The amyloid deposited in the cerebral vessels, senile plaques and intestinal vessels showed characteristic green birefringence under the polarized light even after potassium permanganate treatment.

Age Factors↗
PubMed1990

Early changes in fine structures of the aortic arch in hamsters fed a high cholesterol diet.

Intimal changes at the prelesional stage of atherosclerotic lesions were investigated ultrastructurally using hamsters fed a high cholesterol diet for 1 day to 1 month. Observations were restricted to the lesion-prone area in the aortic arch. The endothelial cells began to show well-developed rough endoplasmic reticulum and Golgi apparatus after a few days of the cholesterol diet. After three days, macrophages which contained a few lipid droplets were observed just below the endothelium. We found that the intimal smooth muscle cell formed a gap junction with the process of the medial smooth muscle cell. After a few weeks to 1 month on the diet, the intima became markedly thickened and filled with dense extracellular matrices. The intimal smooth muscle cells showed well-developed rough endoplasmic reticulum and Golgi apparatus with immature granules, suggestive of high secretory activity. The present study showed that endothelial ultrastructural changes, macrophage invasion, and medial smooth muscle cell migration are very early events occurring within a few days after cholesterol intake commences.

Animals↗
PubMed1990

[An immunohistochemical investigation of estrogen receptor in human breast cancer].

An immunohistochemical investigation of 62 human breast Cancers has been conducted using two different monoclonal antibodies, ER-ICA and ER-D 5, for the demonstration of the estrogen receptor. ER-ICA was found to be positive in 28 cases (45.9%) whereas ER-D 5 was positive in 41 cases (68.3%). In 34 cases, the results were compared to results of a biochemical assay that employed dextran-coated charcoal. The overall concordance between the ER-ICA and the DCC was 78.8%, whereas ER-D 5 and DCC was 60.6%. We thus have concluded that ER-ICA is the more sensitive antibody for evaluating the estrogen receptor status in human breast cancer cases by this immunohistochemical analysis.

Adenocarcinoma↗
PubMed1990

[Evaluation of the changes in intracranial water, sodium, phosphorus metabolites and intracellular cerebral pH in rats with acute dilutional hyponatremia].

Although most prominent among the clinical manifestations associated with hyponatremia are central nervous system (CNS) symptoms, the alterations in brain function remain poorly understood. In the present study, the alterations in intracellular cerebral pH and intracranial water, sodium and phosphorus metabolites content in rats with acute dilutional hyponatremia were examined by using an in vivo nuclear magnetic resonance (NMR) technique which noninvasively provides continuous informations on intracellular phenomena. Acute dilutional hyponatremia was induced on anesthetized male Sprague-Dawley rats by intraperitoneal injection of distilled water with an initial dose of 10 ml/100 g bw, followed by an additional dose of 5 ml/100 g bw 40 min later. Arterial blood sampling and NMR measurements were made before and every 60 min after the initial injection of distilled water. The treatment with distilled water resulted in dramatic falls in serum Na, Cl and osmolality at 60 min after water loading (Na; from 143.4 +/- 2.6 to 112.3 +/- 1.3 mmol/l, Cl; from 101.02 +/- 2.2 to 78.4 +/- 5.4 mmol/l, Osm; from 306.3 +/- 5.8 to 247.3 +/- 7.3 mOsm/kg H20). 1H-NMR imaging showed the accumulation of brain water as dilutional hyponatremia developed. Intracranial Na content measured by 23Na-NMR spectroscopy decreased significantly at 60 min after of water loading to about 70% of that observed under control condition. Since it has been demonstrated that solute extrusion from the brain with resultant reduction of brain swelling occurs within 60 min after the dilution, this result may be, at least in part, explained by this protective mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1990

[Detection of causative bacteria for bovine mastitis and their susceptibility to beta-lactam antibacterial agents].

During the period from November 1988 to May 1989, causative bacteria in a total of 172 clinical mastitis cases observed in 66 farms in 5 districts with 6 areas in Japan were examined and frequencies of their occurrences were determined. Susceptibilities (in MICs) of the isolates to 6 beta-lactam antibacterial agents were also determined. As a result, coagulase-negative staphylococci (CNS) was identified in 94 out of 172 cases (54.7%) and were the most prevalent. Corynebacterium spp., Gram-negative bacteria and Staphylococcus aureus were found in 52 (30.2%), 49 (28.5%) and 43 (25.0%) cases, respectively. Four species of Streptococcus family (S. agalactiae, S. dysgalactiae, S. uberis and S. bovis) were identified in a total of 58 cases (33.7%). Susceptibility testing of CNS to cefoperazone (CPZ), cefazolin (CEZ), benzylpenicillin (PCG), ampicillin (ABPC), methicillin (DMPPC) and cloxacillin (MCIPC) showed that all MIC80's (inhibiting bacterial growth of 80% of all isolates) were within a range from 0.10 to 3.13 micrograms/ml and that there was no marked differences in antibacterial effects among the antibiotics used. The highest antibacterial effect on S. aureus was exhibited by MCIPC, which inhibited the growth of all isolates at 0.39 microgram/ml. The MICs of DMPPC against all isolates of S. aureus were 3.13 micrograms/ml or less and no methicillin-resistant S. aureus (MRSA) was detected. There was no difference in antibacterial activities against Streptococcus family between penicillin antibiotics (DMPPC, MCIPC, ABPC and PCG) and cephem antibiotics (CPZ and CEZ), both of which showed excellent antibacterial activities. Cephem antibiotics exhibited higher activities against Gram-negative bacteria than penicillin antibiotics. Especially CPZ, the third generation cephem, showed excellent antibacterial activity against Escherichia coli, Klebsiella spp., Enterobacter spp., as well as against other Enterobacteriaceae.

Animals↗
PubMed1990

Mandibular movement trajectories and masticatory muscle activities in the rabbit in the sleep and wake states.

Jaw movements and masticatory muscle activities were recorded in freely moving rabbits. During 5 hours of continuous recording, three states were recognized, namely, sleep, rhythmical jaw movements, and wake without any major jaw movements. The rhythmical jaw movements included chewing, drinking, and grooming and were similar in characteristics to those recorded in immobilized animals. During sleep, two kinds of masseter muscle behaviors with jaw movement features were recorded: one characterized by a short EMG bursts and a pause in jaw movements, considered similar to clenching, and the other characterized by cyclic bursts and lateral jaw excursion, a grinding-like movement. The latter was correlated with light sleep, thus suggesting a resemblance between the grinding-like behavior and bruxism.

Animals↗
PubMed1990

[Hyponatremia in isolated deficiency of adrenocorticotropic hormone: role of a decrease in aldosterone secretion independent of antidiuretic hormone excess].

We report a case of 47-year-old woman with an isolated deficiency of adrenocorticotropic hormone. She was admitted complaining of fatigue and frequent loss of consciousness. The patient developed severe hyponatremia (100 mEq/l) after five days of the admission. Her plasma renin activity and plasma aldosterone concentration were low though she was dehydrated. After the treatment of dehydration, plasma osmolality was low but high plasma antidiuretic hormone (ADH) level sustained. Both high urinary sodium excretion and low urinary aldosterone excretion still remained after one month of replacement therapy with prednisolone. But, glomerular filtration rate and a response of urinary volume to acute water loading were normalized. These results suggested that severe hyponatremia of the patient was caused by an inappropriate secretion of ADH and suppression of renin-aldosterone system. We consider the suppression of renin-aldosterone system was partially independent of an inappropriate secretion of ADH.

Adrenocorticotropic Hormone↗