Biomedical subjects

M Sakamoto

Publications and source records attributed to M Sakamoto.

At least 217 records · Page 12Linked to original sources

PubMed1998

Intravenous glucose tolerance test-derived glucose effectiveness in strength-trained humans.

The effect of long-term strenuous resistance training on glucose effectiveness (SG) was examined by comparing 11 strength-trained and 20 sedentary males by a minimal model approach. Lean body mass (LBM) was measured by hydrostatic weighing. The LBM in strength-trained subjects (65.7 +/- 3.1 kg) was significantly larger than in sedentary subjects (56.6 +/- 1.2 kg, P < .01). The glucose disappearance constant ([KG] 3.07% +/- 0.45% min(-1)) and insulin sensitivity ([SI] 17.5 +/- 2.0 x 10(-5) x min(-1) x pmol/L(-1)) in strength-trained subjects were significantly higher than in sedentary subjects (2.06% +/- 0.14% x min(-1) and 10.3 +/- 1.2 x 10(-5) x min(-1) x pmol/L(-1), P < .05). SG in strength-trained subjects (0.024 +/- 0.003 min(-1)) was significantly higher than in sedentary subjects (0.018 +/- 0.001 min(-1), P < .05). These results thus suggest that the improved glucose tolerance in strength-trained subjects was due to increased SG and SI.

Adult↗

PubMed1998

GABAergic inhibition of hiccup-like reflex induced by electrical stimulation in medulla of cats.

We hypothesize that the hiccup reflex is actively inhibited through GABA(B) receptor within central connections of the hiccup reflex arc. Because the hiccup-like reflex can be elicited by electrical stimulation to a limited area within the medullary reticular formation, the hiccup-evoking site (HES), electrical stimulation (50-100 microA, three train pulses at 20 Hz) was delivered to HES by means of a metal electrode containing 1.0 mM baclofen, in anesthetized spontaneously breathing cats. The evoked response was characterized by a brief powerful increase in diaphragmatic activity and a temporal suppression of the posterior cricoarytenoid muscle, laryngeal dilator, which corresponded to the fixed motor pattern of hiccup reflex. The hiccup-like response was rapidly suppressed after microinjection of baclofen (0.1-0.5 nmol) into HES, indicating that HES has GABA(B) receptors. In the other experiments, to histologically examine the inputs to the hiccup reflex arc, unconjugated cholera toxin subunit B (UCTB) was injected into HES. Following injections of UCTB, retrogradely labelled cells were found distributed in various areas of the lower brainstem. Among these areas, the nucleus raphe magnus (RM) is reported to have GABA-containing cells. It is thus hypothesized that RM is most likely to be the source of the GABAergic inhibitory inputs to the hiccup reflex arc.

Animals↗

PubMed1998

Hyperplastic foci reflect the risk of multicentric development of human hepatocellular carcinoma.

BACKGROUND/AIMS: Identification of the risk factors of multicentric hepatocarcinogenesis is important for the clinical management of hepatocellular carcinoma. We investigated hyperplastic foci in non-cancerous liver parenchyma, and clarified their pathological features and clinical significance. METHODS: Hyperplastic foci were defined as hypercellular areas, which architecturally and cytologically resembled early hepatocellular carcinoma or adenomatous hyperplasia but did not form macroscopically detectable nodules. Surgically resected livers from 155 patients with hepatocellular carcinoma were examined histopathologically and immunohistochemically. RESULTS: Hyperplastic foci were found in 26 of 155 patients (16.8%). All the patients with hyperplastic foci had chronic liver diseases, and the incidence did not differ between those with chronic hepatitis and those with liver cirrhosis. Six of 92 (6.5%) patients with single primary hepatocellular carcinoma nodules, 8 of 42 (19.0%) with two nodules, and 12 of 21 (57.0%) with more than three nodules had hyperplastic foci. The incidence of hyperplastic foci showed a significant positive correlation with the multiplicity of hepatocellular carcinoma nodules. Immunohistochemically, hyperplastic foci were masses of proliferative hepatocytes similar to adenomatous hyperplasia and early hepatocellular carcinoma. CONCLUSIONS: Hyperplastic foci reflect the risk of multicentric hepatocarcinogenesis. Our results suggest strongly that hyperplastic foci are precursors of adenomatous hyperplasia or hepatocellular carcinoma.

Adult↗

PubMed1998

Repair of wounded monolayers of cultured vascular endothelial cells after simultaneous exposure to lead and zinc.

We investigated the interaction between lead and zinc on the repair of wounded monolayers of cultured bovine aortic endothelial cells. A half area of the monolayers was wounded and then incubated in the presence of lead (5.0 and 10 microM) and/or zinc (10 microM). It was morphologically observed that the appearance of the cells in the wounded area was strongly decreased by lead alone but considerably increased by zinc alone. The repair of wounded area after simultaneous exposure to lead and zinc showed that lead inhibits not only spontaneous but also zinc-promoted repair of endothelial cell layers without a change of the leakage of lactate dehydrogenase. Interaction between lead and zinc on the DNA synthesis of growing endothelial cells was similar to that on the repair, suggesting that the repair reflected the proliferation. In growing endothelial cells, the intracellular accumulation of lead was significantly increased by zinc; that of zinc was unaffected by lead; and that of metallothionein was slightly increased by zinc and lead but the effect of zinc was suppressed in the presence of lead. Although zinc significantly decreased the intracellular accumulation of radioactive calcium, lead increased it in the presence or absence of zinc. It was therefore concluded that lead inhibits not only spontaneous but also zinc-promoted repair of the damaged endothelial cell layers through an inhibition of the proliferation mediated by the calcium-mediated signalling pathways and/or a disturbance of intracellular calcium homeostasis.

Animals↗

PubMed1998

Physiologic role of the complement system in host defense, disease, and malnutrition.

The role of the complement system as a system merging early-phase innate immunity with later-phase acquired immunity has been established. C3 is a key protein of the complement system. It is activated in four pathways: (1) the alternative pathway, (2) the mannan binding protein pathway, (3) the C-reactive protein pathway, and (4) the natural IgM pathway in innate immunity. It is also activated in (1) a classic pathway, i.e., through an antigen-antibody complex, and (2) by injured host cells in acquired immunity. Activation of C3 results in a variety of immunologic reactions such as immune adherence, phagocytosis, antibody response, cytolysis, inflammation, and killing of pathogenic microorganisms. Pathologic pictures of the complement system in various diseases were reviewed. Attention was focused on hypocomplementemia in the malnourished state. In humans and in experimental animals, reduced complement levels, especially of C3, were observed in relation to lowered host defense against infection. Hypocomplementemia improved after nutritional rehabilitation with a concomitant improvement of the clinical picture and recovery of host resistance. Enhancement of C3 levels in malnourished or well-nourished rats resulted in heightened resistance against bacterial infections. On the basis of these experimental and clinical observations, we obtained clues to prevent or treat a compromised host defense system in malnourished states.

Animals↗

PubMed1998

An intravascular chemoattractant lectin inhibits neutrophil migration.

KM+, a lectin purified from Artocarpusintegrifolia seeds, is an attractant for neutrophils, and has properties similar to fMLP, IL-8 and MNCF. The endogenous lectin MNCF, inhibits carrageenan-induced neutrophil migration when intravenously administered in rats. In an attempt to mimic the activity of MNCF with KM+, we determined the effect of intravenous (iv) injection of KM+ (5 microg) on neutrophil migration to the peritoneal cavity of Wistar rats induced by KM+ (50 microg, intraperitoneal, ip), fMLP (5 ng, ip) and carrageenan (300 microg, ip). Initially we evaluated the effect of the time interval between intravenous and intraperitoneal administration of KM+. The intervals ranged from 20 to 120 min and progressively stronger inhibition was observed with increasing time intervals up to a maximum of 60 min, with effect decreasing thereafter. With injections at the optimum interval of 60 min, we observed that KM+ inhibited KM+- and carrageenan-induced neutrophil migration by 72%, and fMLP-induced migration by 56%. White cell counts for Wistar rats that only received KM+iv, performed at 0 to 120 min intervals after injection, revealed early neutropenia lasting 60 min, followed by a marked increase in circulating neutrophils that reached a maximum of twice the initial levels within 90 min and after 120 min returned to levels near to that observed before intravenous administration of KM+. These results indicate that when KM+ is present in the intravascular space, it produces an inhibitory effect on neutrophil migration similar to that caused by the intravenous administration of other chemoattractants, regardless of whether they act through a mechanism independent of carbohydrate recognition, as does IL-8, or are dependent on carbohydrate recognition, like MNCF.

Animals↗

PubMed1998

Average thresholds in the 8 to 20 kHz range in young adults.

The sound-pressure level thresholds in the extended high-frequency range (8 to 20 kHz) were measured in 25 non-hearing-impaired young adults from 20 to 29 years of age. The result was not unlike that obtained by previous investigators; the thresholds increased gradually as a function of frequency. However, two notable points were found: one that the threshold reached a plateau above 18 kHz, and the other that it decreased slightly at 12 kHz. As the subjects might respond to the low-frequency noise of the stimulus wave, the threshold became a plateau above 18 kHz. An acoustic resonance in the ear canal caused the threshold to decrease at 12 kHz. In clinical studies of extended high-frequency audiometry, the threshold data should be carefully evaluated above 18 kHz and at 12 kHz.

Adult↗

PubMed1998

Average thresholds in the 8 to 20 kHz range as a function of age.

The sound-pressure thresholds at the extended high frequencies of 8-20 kHz were measured for 65 normal subjects aged between 10 and 69 years. The results are not unlike those obtained by previous investigators. The thresholds increased gradually as a function of frequency, except around 12 kHz and above 19 kHz, and also as a function of age. To clarify the connections between threshold, frequency and age, we introduced the regression lines for the threshold by analysing two ranges of frequencies (8-10 kHz and 14-19 kHz) and determining their slopes and intercepts. The regression line analysis reveals that the thresholds at 8-10 kHz tend to increase more at higher frequencies as subject age increased above 30 to 39 years, and those at 14-19 kHz increase translationally with increase of age. Our results did not contradict earlier reports on the pathological changes of the inner ear.

Adolescent↗

PubMed1998

Aortitis syndrome (Takayasu's arteritis) with cataract and elevated serum level of vascular endothelial growth factor.

The aortitis syndrome is a chronic inflammatory process that affects the aorta and its primary branches. Patients with aortitis syndrome exhibit various ocular changes. We present a patient in whom cataract was the initial objective finding. The serum concentration of vascular endothelial growth factor, a cytokine that affects neovascularization, and vasopermeability, was elevated before the initiation of prednisolone treatment. Cataract should be considered as a possible characteristic initial finding in patients with aortitis syndrome. Vascular endothelial growth factor may be involved in the progression of aortitis syndrome.

Adult↗

PubMed1998

Vascular endothelial growth factor in patients with rheumatoid arthritis.

To examine the role of vascular endothelial growth factor (VEGF), an endothelial cell specific growth factor, in rheumatoid arthritis (RA), serum concentration of VEGF was examined in patients with RA, osteoarthritis (OA), systemic lupus erythematosus (SLE), systemic sclerosis (SS) and control subjects. Serum C-reactive protein (CRP) level, erythrocyte sedimentation rate, white blood cell count and rheumatoid factor titer were also determined in patients with RA. The serum concentration of VEGF was significantly higher in patients with RA than in controls (p < 0.01), and patients with OA (p < 0.05), SLE (p < 0.05), and SS (p < 0.05). The serum concentration of VEGF correlated with serum levels of CRP (r = 0.698, p < 0.0001). The serum concentration of VEGF before treatment was significantly higher than that after treatment in patients with RA who experienced clinical remission (p < 0.05). Our data suggest that VEGF is involved in the pathogenesis of RA and that measurement of serum concentration of VEGF is a noninvasive, useful method for monitoring the disease activity of RA.

Adolescent↗

PubMed1998

Dynamics of hepatitis C viremia following interferon-alpha administration.

Knowledge of the dynamics of hepatitis C virus (HCV) in vivo is important for elucidation of its pathogenesis and the establishment of therapeutic guidelines. The aim of this study was to obtain kinetic information about virus load following interferon-alpha (IFN-alpha) administration. Serial serum HCV core protein and HCV RNA levels were measured. IFN-alpha exponentially reduced serum HCV levels. The mean (+/-SD) viral half-life was 7.0 +/- 2.6 h in HCV core protein assay and 7.2 +/- 3.1 h in HCV RNA assay on the first day of therapy. This initial rapid decrease was followed by a slower decrease in serum HCV levels thereafter. Thus, the biphasic reduction in virus load during IFN-alpha therapy was demonstrated.

Adult↗

PubMed1998

Natural history and prognosis of adenomatous hyperplasia and early hepatocellular carcinoma: multi-institutional analysis of 53 nodules followed up for more than 6 months and 141 patients with single early hepatocellular carcinoma treated by surgical resection or percutaneous ethanol injection.

BACKGROUND: The natural history and posttherapeutic outcome of adenomatous hyperplasia and early hepatocellular carcinoma have rarely been analyzed. METHODS: Fifty-three hepatic tumors diagnosed as adenomatous hyperplasia or early hepatocellular carcinoma and followed up for more than 6 months and 141 patients with single early hepatocellular carcinoma treated by surgical resection or ethanol injection were collected retrospectively and analyzed. RESULTS: Some of the adenomatous hyperplasias developed to early and to advanced hepatocellular carcinoma. Tumors tended to grow faster in the order adenomatous hyperplasia, early hepatocellular carcinoma and advanced hepatocellular carcinoma, with respective mean (SD) tumor volume doubling times of 21.2 (10.7), 13.9 (11.7) and 6.0 (5.2) months. Overall survival rates at 5 years in 53 patients treated by surgery and 88 patients treated by ethanol injection were 89.6 and 71.9%, respectively. CONCLUSION: Progression of adenomatous hyperplasia and early HCC was confirmed pathologically. Early HCC was shown to have a good prognosis.

Adenoma↗

PubMed1998

Undifferentiated carcinoma of the liver with neuroendocrine features: a case report.

Undifferentiated carcinoma of the liver is very rare. A 54-year-old man was admitted to our hospital for a detailed examination of multiple liver tumors. These tumors were high or low echoic on ultrasonography, but not enhanced by contrast medium in dynamic computed tomography. A fine-needle aspiration biopsy specimen of the tumor showed undifferentiated carcinoma. The serum level of neuron-specific enolase was high (357 ng/ml) and the immunohistochemical stain of the biopsy specimen was positive for synaptophysin. We diagnosed the patient as having undifferentiated carcinoma of the liver with neuroendocrine features. The patient was treated with combined systemic chemotherapy: etoposide 100 mg/m2/day for three days plus cisplatin 80 mg/m2/day on day one. He achieved a partial response, the duration of which was 7+ months. The serum neuron-specific enolase levels were decreased to the normal range after chemotherapy. Primary liver carcinoma with neuroendocrine features is extremely rare, but in a suspicious case it is important to measure the serum levels of neuroendocrine markers and make a histological confirmation, because chemotherapy may be effective for this disease.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

Skin vasomotor reflex predicts circulatory responses to laryngoscopy and intubation.

BACKGROUND: An evaluation of autonomic reactivity may help to predict circulatory responses to intubation. The relation between the magnitude of the skin vasomotor reflex (SVmR) immediately before laryngoscopy and the circulatory responses to intubation was examined. METHODS: Forty-four adult patients (classified as American Society of Anesthesiologists physical status I or II) were studied. General anesthesia was induced with fentanyl and thiamylal and maintained with nitrous oxide and sevoflurane. The SVmR was evoked by an electrostimulus to the ulnar nerve, and decreases in skin blood flow were detected using a laser-Doppler flowmeter. In study 1, two groups of patients were studied. In the monitored group (n = 14), laryngoscopy was performed when the SVmR amplitude had decreased to less than 0.1. In the control group (n = 15), intubation was performed regardless of changes in the SVmR amplitude. In study 2, after induction, the end-tidal concentration of sevoflurane was maintained at 1 MAC (n = 9) or 1.3 MAC (n = 6) for 5 min. The SVmR was tested by changing the electric intensity. RESULTS: In study 1, the blood pressure and heart rate of the control group increased significantly (P < 0.01) after laryngoscopy. The blood pressure of the monitored group did not increase. The SVmR amplitude and the systolic blood pressure changes showed a significant linear correlation (P < 0.001). In study 2, the relation between the electric intensity and the SVmR amplitude showed a weak but significant correlation (P < 0.01) in the 1 MAC group. CONCLUSION: The evaluation of the SVmR provides useful information for determining the optimal anesthetic depth for laryngoscopy and intubation in individual patients.

Adult↗

PubMed1998

Lower than normal expression of brain nitric oxide synthase gene in the hypothalamus of deoxycorticosterone acetate-salt hypertensive rats.

OBJECTIVE: To elucidate the role of brain nitric oxide produced by neuronal constitutive nitric oxide synthase in sodium-induced hypertension. DESIGN AND METHODS: Diets containing a high (8% NaCl), a medium (2% NaCl), and a low (0.2% NaCl) sodium content were administered to Wistar rats aged 12 weeks for 10 days or 8 weeks until they were killed. Male Wistar rats administered either deoxycorticosterone acetate, 1% NaCl or both and the respective controls were killed 2 weeks (during prehypertensive stage) or 6 weeks (during hypertensive stage) after the start of treatment. The hypothalamus and lower brainstem were excised for extraction of total RNA. Reverse transcription polymerase chain reactions of constitutive nitric oxide synthase messenger RNA and glyceraldehyde-3-phosphate dehydrogenase messenger RNA were performed, and constitutive nitric oxide synthase messenger RNA levels were expressed relative to glyceraldehyde-3-phosphate dehydrogenase messenger RNA levels. RESULTS: A high sodium intake for 10 days tended to decrease constitutive nitric oxide synthase messenger RNA levels in the hypothalamus, compared with effect of a low sodium intake. Constitutive nitric oxide synthase messenger RNA levels in the hypothalamus of deoxycorticosterone acetate-salt hypertensive rats were lower than those in the control sham-operated rats. Neither alteration of sodium intake nor administration of deoxycorticosterone with and without sodium affected constitutive nitric oxide synthase gene expression in the lower brainstem. CONCLUSIONS: Expression of neuronal constitutive nitric oxide synthase gene is downregulated in the hypothalamus of deoxycorticosterone acetate-salt hypertensive rats. This lower than normal expression of neuronal constitutive nitric oxide synthase gene in the hypothalamus could be an adaptive response to sodium-induced hypertension, and suggests that nitric oxide produced by hypothalamic constitutive nitric oxide synthase plays a role in maintenance of blood pressure in relation to sodium balance in rats.

Animals↗

PubMed1998

UL-FS 49 (zatebradine) does not affect arterial baroreflex in conscious normal or aortic-constricted rats.

Heart-rate reduction is an important element of patient management during cardiac bypass surgery and in therapeutic measures for combating ischemia and relieving pain in patients with angina. UL-FS 49 is a novel bradycardic agent that purportedly acts solely on the sinoatrial node without potentially deleterious effects on arterial pressure and cardiac inotropism. However, little is known about influences of this agent on neuronal tissue and cardiovascular reflexes. Moreover, left ventricular hypertrophy, which often accompanies cardiovascular disease, is known to attenuate the arterial baroreflex and could have effects interactive with those of UL-FS 49. In this study, the effects of UL-FS 49 on the arterial baroreflex were tested in normal rats (N), rats with left ventricular hypertrophy 14 days after abdominal aortic constriction (AC), and sham-operated controls (SH). Arterial baroreflex sensitivity (BRS) was estimated as the slope of the relation between mean arterial pressure (independent variable) and the RR interval (dependent variable). At the time of study, the AC group had significantly greater mean arterial pressure than either SH or N (159 +/- 2, 122 +/- 3, and 124 +/- 3 mm Hg, respectively; mean +/- SEM, p < 0.01) and significantly greater left ventricular mass to body mass ratio than did SH (3.73 +/- 0.11, 2.33 +/- 0.11 mg/g; p < 0.01). As expected, BRS was significantly depressed in AC, compared with either SH or N (0.52 +/- 0.16, 1.48 +/- 0.12, 1.69 +/- 0.25 ms/mm Hg, respectively; p < 0.01). Despite its potent dose-dependent bradycardic effects in all three groups, UL-FS 49 did not affect BRS significantly in any group. These results show that the arterial baroreflex is largely unaffected by UL-FS 49 in both normal rats and rats with systemic hypertension and left ventricular hypertrophy.

Animals↗

PubMed1998

Expression of the SART-1 antigens in uterine cancers.

We recently reported that the SART-1 gene, encoding the SART-1(259) tumor antigen which is recognized by HLA-A26-restricted cytotoxic T lymphocytes (CTLs), is expressed in the cytosol of squamous cell carcinomas and adenocarcinomas. The present study deals with the expression of SART-1(259) and SART-1(800) antigens in uterine cancers. The SART-1(259) antigen was detected in the cytosol fraction of 4 of 8 uterine cancer cell lines, 24 of 74 (32%) uterine cancer tissues, 0 of 7 uterine myomas, and 0 of 5 non-tumorous uterine tissues. The SART-1(800) antigen was expressed in the nuclear fraction of all the uterine cancer cell lines, 41 of 74 (55%) uterine cancer tissues, 0 of 7 myomas, and 3 of 5 non-tumorous uterine tissues. The SART-1(259)+ uterine cancer cells were recognized by HLA-A24 restricted and SART-1 specific CTLs. Therefore, SART-1(259) antigen could be an appropriate vaccine candidate for a relatively large number of uterine cancer patients.

Adenocarcinoma↗

PubMed1998

[A clinical study of respiratory infection isolating non-pathogenic Neisseria by transtracheal aspiration].

Neisseria species other than N. meningitidis and N. gonorrhoeae are generally regarded as commensal bacterial flora of the oropharynx, and little is known regarding cases of these non-pathogenic Neisseria species in the lower respiratory tract. We clinically examined respiratory tract infections from which non-pathogenic Neisseria species were isolated by transtracheal aspiration (TTA). The incidence of non-pathogenic Neisseria isolated was 54 (15.7%) out of 344 episodes of respiratory tract infections with isolated microorganisms from TTA, and was 17.6%, 15.8%, 14.3% for pneumonia, acute bronchitis, and chronic lower respiratory tract infection, respectively. All 54 episodes were isolated with other microorganisms such as alpha-Streptococcus spp. (75.9%), Haemophilus influenzae (25.9%) and anaerobics (22.2%). The isolation ratio according to the age group increased at 45 years of age or more, but did not increase with the advance of age. Predisposing factors were identified such as overt aspiration, iatrogenic procedure and heavy smoking. Cases without overt aspiration that had fevers of 38 degrees C or more or hypoxemia of less than PaO2 70 torr when detecting non-pathogenic Neisseria were observed more frequently in the aged than the non-aged. The findings suggest the detection of non-pathogenic Neisseria by TTA is influenced by the host state that the fall of microorganisms from the upper to lower respiratory tract cannot be defended or excluded by mucociliary transportation disorder due to underlying disease and smoking, or deterioration of physical status other than overt or silent aspiration.

Age Factors↗