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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 379 records · Page 21Linked to original sources
PubMed1993

Effects of bile acids and taurine on the lipid fluidity of hepatic microsomes in normal and bile duct-ligated rats--a spin label study.

In cholestasis and obstructive jaundice, hepatic bile acids and taurine content increase significantly and bile acids change in compositions. For example, increases in cholic acid, beta-muricholic acid and taurine-conjugated bile acids occur in rats. In this study, to clarify the significance of changes in bile acid composition in obstructive jaundice, the effects of various bile acids and taurine on the fluidity of the hepatic microsomal membrane were studied by the electron spin resonance spin-label method in normal and bile duct-ligated (for 10 days) rats. The flow properties (order parameter) of the shallow and deep layers of the membrane were determined with 5- and 12-doxyl stearic acid, respectively. Bile acids mainly affected the fluidity of the shallow membrane layer. The fluidity of the hepatic microsomal membrane was decreased in bile duct-ligated rats. Conjugated cholic acid (taurine-conjugated cholic acid, glycine-conjugated cholic acid and non-conjugated beta-muricholic acid exerted effects that increased fluidity in comparison with non-conjugated cholic acid and chenodeoxycholic acid, a precursor of beta-muricholic acid. Taurine had no clear effect on fluidity. In conclusion, cholic acid conjugation and beta-muricholic acid formation may be mechanisms which protect against the decrease in lipid fluidity of hepatic biomembranes in cholestasis or obstructive jaundice. Taurine may also affect fluidity through the formation of taurine-conjugated bile acids.

Animals↗
PubMed1993

Effects of arterial-portal glucose difference on gluconeogenesis from lactate in the isolated bivascular-perfused rat liver.

The effects of arterial-portal glucose difference on the gluconeogenesis from lactate were studied using the bivascular perfused liver isolated from the fasted rat. The liver was cyclically perfused at flow rates of 14 ml/min from the portal vein and of 7 ml/min from the hepatic artery with the total volume of 35 ml of perfusion medium containing 2 mM glucose, 3 mM lactate and (U-14C)-lactate for 20 min. Glucose was infused at a rate of 27.75 mumol/min into the arterial cannula (A-experiment) or the portal cannula (P-experiment), making each arterial-portal glucose gradient of +3.96 mM (arterial glucose > portal glucose) and -1.98 mM (arterial glucose < portal glucose) throughout the experiment. Perfusate lactate concentration was lower in A-experiment than in P-experiment (1.40 +/- 0.25 vs 1.93 +/- 0.23 mM at 20 min, mean +/- SD, p < 0.05). Incorporation of radioactivity from (U-14C)-lactate into glucose carbon 1 in perfusate was 5.7 +/- 0.8% of total radioactivity per 20 min in A-experiment vs 2.8 +/- 0.6%/20 min in P-experiment (p < 0.01). These results suggest that the arterial-portal glucose difference is an important factor to regulate the hepatic gluconeogenesis.

Animals↗
PubMed1993

Correlation of sequential magnetic resonance imaging of experimental brain ischemia with histologic changes in gerbils.

RATIONAL AND OBJECTIVES: To characterize Gd-DTPA-enhanced T1-weighted images (Gd-T1WI) in the acute phase of cerebral ischemia, sequential magnetic resonance images of 84 Mongolian gerbils with occlusion of the left common carotid artery were evaluated. METHODS: Twelve gerbils were used for each group, among which the occlusion time (5-180 minutes, permanent) varied. Histopathologic changes developing within the first 2 weeks were compared with patterns on T2-weighted images and Gd-T1WI on a 7.05-Tesla system. RESULTS: Although T2-weighted images and Gd-T1WI both demonstrated abnormal findings as early as 3 hours after occlusion, Gd-T1WI demonstrated more definite abnormalities with shorter occlusion than T2-weighted images (especially when there were only mild histologic changes). The earliest changes were an abnormal enhancement around and within the lateral ventricles in temporary occlusions; this was not demonstrated in permanent occlusions. CONCLUSIONS: Magnetic resonance images using Gd-DTPA demonstrated abnormal permeability within 3 hours after occlusion, and the pattern is correlated with intensity of ischemia.

Animals↗
PubMed1993

Estrogen-sensitive neurons in the female rat ventral tegmental area: a dual route for the hormone action.

1. Electrical stimulation of the ventral part of the midbrain central gray (CG) elicited antidromic action potentials in 136 neurons in the ventral tegmental area (VTA) of 23 urethan-anesthetized ovariectomized female rats. 2. Antidromic action potentials were positive-negative biphasic and completed mostly within 2.4 ms. Many had a notch in their initial positive deflection, at which antidromic potentials often failed to propagate into the neuronal soma. 3. The latency for antidromic activation ranged 1.0-10.5 ms, and the threshold was 100-1,700 microA. The relative refractory period was 0.8-2.8 ms. In 23 neurons (17%) gradual changes in stimulus intensity caused latency jumps, suggesting that their axons terminate or spread into branches in stimulation sites. 4. The parameters for antidromic activation were compared among 12 animals with a subcutaneous Silastic capsule of estrogen and 11 others with a blank capsule. Estrogen raised the mean threshold from 675 +/- 40 (SE) microA (n = 69) to 908 +/- 40 microA (n = 67). At the same time, estrogen significantly decreased the probability of the antidromic propagation from 63 to 41%. No changes were detected in the latency or the refractory period. 5. The probability distribution of the threshold was different in ovariectomized animals from that in estrogen-treated animals. Estrogen increased the number of cells with thresholds in the 1,300- to 1,500-microA range. 6. The probability of antidromic propagation was stable in each neuron to stimuli repeated at 1.0 Hz. Electrical stimulation of the preoptic area (POA) with a 30-s train of 50-microA pulses at 100 Hz increased the probability of antidromic propagation into the soma.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1993

Erythromycin inhibits the production of elastase by Pseudomonas aeruginosa without affecting its proliferation in vitro.

Extracellular proteases from Pseudomonas aeruginosa play important roles in infections in the respiratory tract. The effect of erythromycin (EM), a macrolide antibiotic, on the production of elastase by P. aeruginosa was investigated in vitro and compared with the effect of other antibiotics. Thirty-four (94.4%) of thirty-six different strains produced detectable amounts of elastase determined by the gel diffusion method. The elastase production was inhibited completely by EM in 27 (79.4%) of 34 strains at some concentrations between 0.125 and 64 micrograms/ml. At 4 micrograms/ml or less, the elastase production was inhibited completely in four (11.8%) strains and more than 50% in the other 10 (29.4%). At 8 micrograms/ml or less, the elastase production was inhibited completely in 11 (32.4%) strains and more than 50% in the other nine (26.5%). The proliferation was partially inhibited at 32 and 64 micrograms/ml. Roxithromycin inhibited the elastase production at higher concentrations than EM without inhibiting the proliferation. Midecamycin and ampicillin did not inhibit the elastase production or the proliferation. Doxycycline and ticarcillin inhibited the elastase production and/or the proliferation at concentrations greater than 16 micrograms/ml. Although ofloxacin (OFLX) inhibited both the proliferation and the elastase production in parallel at low concentrations, there were six (16.7%) strains resistant to OFLX. Among them the elastase production was inhibited in five strains by EM. These results suggest that EM acts on P. aeruginosa to inhibit extracellular production of elastase without affecting the proliferation of the bacteria.

Cell Division↗
PubMed1993

Effect of rush immunotherapy in house-dust-mite (HDM)-sensitive adult bronchial asthma: changes in in vivo and in vitro responses to HDM.

An open study was conducted to evaluate the changes in in vivo and in vitro responses to house-dust-mite (HDM) after rush immunotherapy (RI). A 7-day RI protocol using an extract containing HDM allergen was administered to 12 subjects with HDM-sensitive asthma, and the effects on bronchial responsiveness and serum antibody levels were evaluated up to 16 or 20 weeks after RI. The levels of HDM-specific IgG, IgG1 and IgG4 antibodies were significantly elevated from 4 or 8 weeks after RI. Provocative doses causing a 20% fall in FEV1 (PD20) by allergen inhalation were elevated in all subjects at 16 to 20 weeks after RI. There was a high correlation between the increase in log-PD20 and the increase in the ratio of HDM-specific IgG4 to IgG1 (r = 0.68, p < 0.05). The results suggest that RI elicits the improvement of allergen-specific bronchial responsiveness and the increase in serum antibody levels within a relatively short period.

Adolescent↗
PubMed1993

Trial of insulinlike growth factor I therapy for patients with extreme insulin resistance syndromes.

Extreme insulin resistance occurs in patients with primary defects in insulin action at the receptor or postreceptor levels. The condition commonly is associated with acanthosis nigricans and ovarian masculinization. Despite a marked increase in insulin secretion, some patients develop frank diabetes mellitus that does not respond adequately to insulin therapy. Insulinlike growth factor I exerts metabolic effects similar to those of insulin. This study assessed the potential effectiveness of IGF-I as a blood glucose lowering agent in patients with extreme insulin resistance syndromes, including type A insulin resistance, congenital generalized lipodystrophy, and leprechaunism. Among the 11 patients studied, some exhibited mutated insulin receptors, whereas others were suspected to have defects in postreceptor sites. In each patient, plasma glucose levels decreased in response to subcutaneous injections of recombinant human IGF-I (0.1-0.3 mg/kg body wt). The degree of the decrease was roughly comparable with that observed in normal individuals. IGF-I also reduced plasma insulin concentrations. A long-term trial of IGF-I (up to 16 mo) showed that IGF-I (0.1-0.4 mg/kg body wt twice daily) is effective in lowering both fasting and postprandial plasma glucose concentrations with decreases in both fructosamine and HbA1c values. Improvement of acanthosis nigricans was observed in some of the patients. These results suggest that recombinant human IGF-I could be used clinically as a hypoglycemic agent in diabetic patients with extreme insulin resistance in whom insulin treatment is ineffective.

Acanthosis Nigricans↗
PubMed1993

[Immunohistochemical study on the expression of perforin in tumor infiltrating lymphocytes of renal cell carcinoma].

Perforin is considered to be one of the important cytolytic factors found in the granules of killer cells. In this paper we attempted to demonstrate perforin in TIL (tumor infiltrating lymphocytes) of 55 human renal cell cancer cases and the perforin was proved by staining immunohistochemically with an anti-PFP monoclonal antibody. The result indicated that perforin was observed in 98% of the cases, while few positive cell was found in normal renal tissues. TILs were further characterized into their subsets including CD4+ T cells, CD8+ T cells, NK cells and gamma/delta T cells using antibodies specific to their surface markers. The antibodies used are anti-Lew3a, anti-Lew2a, anti-Lew19 and anti-delta chain antibody. The former two subsets were predominantly found to be infiltrating in the tumor tissue, while the latter two subsets were shown to be lesser than the former. For examination of the correlation between the presence of perforin and the characteristics of infiltrated lymphocyte subsets, double-staining of the cells was performed using anti-perforin and one of anti-surface marker antibodies, respectively. The perforin was found to be expressed on the four subsets at different extent. A stronger reactivity of the perforin was found in the CD4+ T cells and CD8+ T cells than that in the NK cells and the gamma/delta T cells. These findings suggest that perforin may play a role of effector functions in the immunological defense mechanism against cancer. To define the significance of the expression of the perforin not only on the CD8+ T cells but also on the CD4+ T cells is required for further study.

Adult↗
PubMed1993

Effects of ethanol on the motility of papillary sphincter and exocrine pancreas in the monkey.

The effects of acute and chronic ethanol administration on the motility of the papillary sphincter, pancreatic duct pressures, and exocrine pancreas were studied. Acute administration (n = 5) significantly reduced the peak pressure of the papillary sphincter from 84.2 +/- 19.6 to 15.8 +/- 3.0 mm Hg (p < 0.05) and increased the frequency from 0.041 +/- 0.002 to 0.067 +/- 0.005/s (p < 0.01). Chronic administration (n = 5) significantly increased pancreatic duct pressure and frequency of the papillary sphincter from 8.6 +/- 2.9 to 22.1 +/- 2.9 mm Hg (p < 0.01) and from 0.039 +/- 0.002 to 0.071 +/- 0.004/s (p < 0.01), respectively. However, it reduced the peak pressure of the papillary sphincter from 84.8 +/- 15.1 to 21.1 +/- 2.8 mm Hg (p < 0.05). Electron microscopy showed dilation and a concentric arrangement of the rough endoplasmic reticulum in the acinar cells. The exocrine function test showed an increased concentration and output of bicarbonate, protein, and amylase. These findings suggest that chronic alcohol intake may cause papillary dysfunction and pancreatic exocrine hypersecretion, which could play a role in increasing pancreatic duct pressure.

Amylases↗
PubMed1993

Aesthetic dental technique using a computer imaging system.

Patients are concerned about their appearance following an operation and would appreciate a preview of the final results. The key to treating a patient's anterior teeth is to first analyse his or her face, then develop a new tooth shape that is both functional and aesthetic. A computer imaging system can objectively portray the appearance which can be expected following an operation. Such a system, therefore, can be a very useful part of the armamentarium for analysis during the patient's pretreatment consultation.

Esthetics, Dental↗
PubMed1993

[Imaging of the pituitary gland].

Several modalities including plain radiography, CT, and MRI are available for evaluation of the intrasellar, suprasellar and parasellar lesions. Plain radiography, which may used for screening, can identify calcification as well as the elusive and destructive changes of the sella turcica and it's adjacent bony structures. CT is much more sensitive in detecting calcifications. It is also useful for demonstrating bony changes in detail. MRI has been thought to be the best modality in evaluation of sellar and parasellar lesions. Dynamic MRI is a choice of method when microadenoma is suspected.

Adolescent↗
PubMed1993

[Excellent exposure for the mitral valve by means of dissection of the interatrial groove].

A technique to approach the mitral valve through a left atrial incision under dissecting the interatrial groove is described. The dissection of the interatrial groove makes the left atrial incision more anterior and medial. Therefore excellent mitral valve exposure was obtained. 40 of 61 mitral valvular procedures during past 1.5-year period were approached through this incision. We could achieve better exposure of the mitral valve than that of conventional atrial incision technique. This technique takes not so long time and rarely carries complications including dysarrhythmia and bleeding.

Cardiac Surgical Procedures↗
PubMed1993

[The analysis of factors contributing to the safety and efficacy of rush immunotherapy in bronchial asthma].

In order to establish guidelines for the optimal use of rush immunotherapy (RI) in mite-sensitive adult bronchial asthmatics, we clinically analyzed 38 cases treated with RI. In all cases, it was possible to reach a maintenance dose greater than 0.10 ml of 1/10 solution of house dust (HD) within 10 days. Most of the systemic reactions occurred after doses greater than 0.15 ml of 1/10 solution. The patients who showed the maximum size of skin reaction > or = 8 cm were susceptible to systemic reactions. Prior to the occurrence of asthma, most cases complained of some prodrome of airway irritation. The clinical efficacy of RI was significantly lower in patients whose FEV1% was < 70%, and no difference was observed between patients whose maintenance dose was 0.10 ml and those whose maintenance dose was greater than 0.20 ml. These results suggest: 1) RI should be performed on patients whose FEV1% is > or = 70%, 2) 0.10 ml of 1/10 solution is an optimal dose, 3) when a local skin reaction is > or = 8 cm in diameter and/or a prodrome of airway irritation occurs, one should be careful when increasing the dosage.

Adolescent↗
PubMed1993

[Improvement of intractable nocturnal asthma treated by therapeutic awakening].

A 33-year-old female was admitted to our hospital because of intractable asthma which had not been improved by intensive treatment at another hospital. Her asthmatic attacks were improved within a week by treatments including systemic corticosteroids and mechanical ventilation. However, in a few weeks nocturnal asthma recurred frequently, and it was resistant to various bronchodilators and steroids. Therapeutic awakening, that is, awakening the patient quietly at 3 a.m. with inhalation of 2.5 mg salbutamol was started. Her symptoms and physical findings rapidly improved thereafter. It was concluded that therapeutic awakening may be effective for the treatment of refractory morning dipping of asthma.

Adult↗
PubMed1993

[Antitumor activity of combination treatment of BOF-A2 with CDDP against human lung cancers xenografted in nude mice].

CDDP, commonly used in cancer chemotherapy, behaves as not only effector but also modulator of 5-FU when combined with 5-FU and the derivatives. Therefore, the antitumor activity of combination treatment of BOF-A2, a new 5-fluorouracil derivative, with CDDP was evaluated with two human lung cancers (H-74 and LC-376) xenografted in nude mice. BOF-A2 was orally administered at 30 mg/kg (MTD) or 15 mg/kg (1/2 MTD) 3 times a week totally twelve times, and CDDP was administrated interperitoneally at 5 mg/kg (MTD) or 2.5 mg/kg (1/2 MTD) once a week totally 4 times. The antitumor effect of combination of two drugs at the 1/2 MTD was effective to H-74 and markedly effective to LC-376, and the effect was more remarkable than each drug administered individually at the 1/2 MTD, and the combination effect was additive. The effect by the combination was not synergistic but showed a similar activity compared with single drug given individually at the MTD. Moreover, the side effect of combination of the 1/2 MTD was less than group given MTD of CDDP in terms of body weight loss. These data suggests a clinical usefulness of combination BOF-A2 with CDDP against lung cancer.

Adenocarcinoma, Papillary↗
PubMed1993

[Accordance of the chemosensitivity between clinical specimens and their xenografts in nude mice by SDI test and the value of in vivo chemosensitivity test using nude mice].

We assessed the sensitivity to anticancer drugs by SDI (succinate dehydrogenase inhibition) test with 11 clinical specimens obtained from operated patients. The results were compared with those of xenografted specimen in nude mice, using the adjuvant part of the specimens assayed. Chemosensitivity of clinical specimens against 3 drugs is mitomycin (MMC), adriamycin (ADM) and cisplatin (CDDP), showed a good accordance (73%) with those of xenografted tumors. The drug sensitivity was considered to be one of the features of original tumors and to be well preserved in the xenografts in nude mice. We also studied in vivo experimental chemotherapy on 19 tumor lines in nude mice to compare the chemosensitivity with clinical response to the same chemotherapy observed in each donor patient. A close correlation (83% on responder, 100% on non-responder and the overall predicting accuracy rate were 95%) was shown, suggesting in vivo nude mouse assay having an excellent predictability for clinical results.

Adult↗