Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 109 records · Page 6Linked to original sources

PubMed2001

Melanin and blood concentration in human skin studied by multiple regression analysis: experiments.

Knowledge of the mechanism of human skin colour and measurement of melanin and blood concentration in human skin are needed in the medical and cosmetic fields. The absorbance spectrum from reflectance at the visible wavelength of human skin increases under several conditions such as a sunburn or scalding. The change of the absorbance spectrum from reflectance including the scattering effect does not correspond to the molar absorption spectrum of melanin and blood. The modified Beer-Lambert law is applied to the change in the absorbance spectrum from reflectance of human skin as the change in melanin and blood is assumed to be small. The concentration of melanin and blood was estimated from the absorbance spectrum reflectance of human skin using multiple regression analysis. Estimated concentrations were compared with the measured one in a phantom experiment and this method was applied to in vivo skin.

Biophysical Phenomena↗

PubMed2001

Melanin and blood concentration in a human skin model studied by multiple regression analysis: assessment by Monte Carlo simulation.

Measurement of melanin and blood concentration in human skin is needed in the medical and the cosmetic fields because human skin colour is mainly determined by the colours of melanin and blood. It is difficult to measure these concentrations in human skin because skin has a multi-layered structure and scatters light strongly throughout the visible spectrum. The Monte Carlo simulation currently used for the analysis of skin colour requires long calculation times and knowledge of the specific optical properties of each skin layer. A regression analysis based on the modified Beer-Lambert law is presented as a method of measuring melanin and blood concentration in human skin in a shorter period of time and with fewer calculations. The accuracy of this method is assessed using Monte Carlo simulations.

Biophysical Phenomena↗

PubMed2001

A 5-year retrospective examination of cognitive screening test stages in normal older adults and patients with Alzheimer's disease: the Tajiri project.

One conception of aging and cognitive deterioration is that cognitive decline becomes common with age, and dementia may be regarded as one extreme of the continuum. An alternative conception is that the cognitive process is spared by the aging process itself and that cognitive functioning of normal older adults and those with slight cognitive impairment, a CDR (Clinical Dementia Rating) score of 0.5 (suspected dementia), should be different. We examined changes in the screening test performances of 170 older adults over a 5-year period and found the following: (a) The CDR 0 (normal) participants did not show remarkable changes even in the older groups and (b) the subitems of orientation, memory, and so forth were useful for distinguishing normal older adults from early Alzheimer's disease patients. The results support the idea that dementia is better conceptualized as an age-related than as an "aging-related" disorder and that a CDR score of 0.5 should be considered very mild Alzheimer's disease.

Aged↗

PubMed2001

Phosphatidylinositol 3-kinase in cumulus cells and oocytes is responsible for activation of oocyte mitogen-activated protein kinase during meiotic progression beyond the meiosis I stage in pigs.

The roles of phosphatidylinositol 3-kinase (PI 3-kinase) during meiotic progression beyond the meiosis I (MI) stage in porcine oocytes were investigated. PI 3-kinase exists in cumulus cells and oocytes, and the PI 3-kinase inhibitor, LY294002, suppressed the activation of mitogen-activated protein (MAP) kinase in denuded oocytes during the beginning of the treatment. However, in denuded oocytes cultured with LY294002, the MAP kinase activity steadily increased, and at 48 h of cultivation MAP kinase activity, p34(cdc2) kinase activity, and proportion of oocytes that had reached the meiosis II (MII) stage were at a similar level to those of oocytes cultured without LY294002. In contrast, LY294002 almost completely inhibited the activation of MAP kinase, p34(cdc2) kinase activity, and meiotic progression to the MII stage in oocytes surrounded with cumulus cells throughout the treatment. Treating cumulus oocyte complexes (COCs) with LY294002 produced a significant decrease in the phosphorylation of connexin-43, a gap junctional protein, in cumulus cells compared with that in COCs cultured without LY294002. These results indicate that PI 3-kinase activity in cumulus cells contributes to the activation of MAP kinase and p34(cdc2) kinase, and to meiotic progression beyond the MI stage. Moreover, gap junctional communications between cumulus cells and oocytes may be closed by phosphorylation of connexin-43 through PI 3-kinase activation in cumulus cells, leading to the activation of MAP kinase in porcine oocytes.

Animals↗

PubMed2001

Dynamic changes of connexin-43, gap junctional protein, in outer layers of cumulus cells are regulated by PKC and PI 3-kinase during meiotic resumption in porcine oocytes.

Mammalian oocytes are surrounded by numerous layers of cumulus cells, and the loss of gap junctional communication in the outer layers of cumulus cells induces meiotic resumption in oocytes. In this study, we investigated the dynamic changes in the gap junctional protein connexin-43 in cumulus cells during the meiotic resumption of porcine oocytes. The amount of connexin-43 in all layers of cumulus cells recovered from cumulus-oocyte complexes was increased after 4-h cultivation. However, at 12-h cultivation, the positive signal for connexin-43 immunoreactivity was markedly reduced in the outer layers of cumulus cells. When these reductions of connexin-43 were blocked by protein kinase C (PKC) or phosphatidylinositol (PI) 3-kinase inhibitor, networks of filamentous bivalents (i.e., advanced chromosomal status) were undetectable in the germinal vesicle of the oocyte. After 28-h cultivation, when the majority of oocytes were reaching the metaphase I (MI) stage, the connexin-43 in the inner layers of cumulus cells was phosphorylated, regardless of mitogen-activated protein (MAP) kinase activation. These results suggest that the initiation of meiotic resumption, namely, the formation of networks of filamentous bivalents in germinal vesicle, is associated with the reduction of gap junctional protein connexin-43 in the outer layers of cumulus cells via the PKC and/or PI 3-kinase pathway. Moreover, the connexin-43 in the inner layers of cumulus cells is phosphorylated during meiotic progression beyond the MI stage, regardless of MAP kinase activation in cumulus cells surrounding the oocyte.

Animals↗

PubMed2001

Inhibition of phosphatidylinositol 3-kinase or mitogen-activated protein kinase kinase leads to suppression of p34(cdc2) kinase activity and meiotic progression beyond the meiosis I stage in porcine oocytes surrounded with cumulus cells.

In this study, the effects of U0126 that inhibits the activity of mitogen-activated protein (MAP) kinase kinase (MEK), and LY294002, which is a phosphatidylinositol (PI) 3-kinase inhibitor, on meiotic progression beyond the metaphase I (MI) stage in porcine oocytes were examined. Cumulus-oocyte complexes (COCs) were cultured for 22 h with 50 microM LY294002 or 10 microM U0126 following cultivation for the initial 22 h. MAP kinase activity in oocytes cultured with LY294002 or U0126 was significantly lower than that in control oocytes cultured for up to 44 h. U0126 and LY294002 significantly decreased p34(cdc2) kinase activity and the proportion of oocytes reaching the MII stage compared to those in control oocytes. Oocytes denuded after COCs had been cultured for 22 h were cultured further for 22 h with U0126 or LY294002. In the denuded oocytes, U0126 suppressed MAP kinase activity, p34(cdc2) kinase activity, and meiotic progression to the MII stage; however, LY294002 did not significantly affect the activity of these kinases and meiotic progression. These results suggest that increasing MAP kinase activity in oocytes via the PI 3-kinase signaling pathway in cumulus cells is involved in the stimulation of maturation promoting factor, leading to meiotic progression beyond the MI to MII stage in porcine oocytes.

Animals↗

PubMed2001

Intravenous anesthetics inhibit nonadrenergic noncholinergic lower esophageal sphincter relaxation via nitric oxide-cyclic guanosine monophosphate pathway modulation in rabbits.

BACKGROUND: Nonadrenergic noncholinergic (NANC) nerves have important roles in the regulation of the lower esophageal sphincter (LES) motility and function. The effects of thiopental, ketamine, and midazolam on NANC LES relaxation were investigated. METHODS: The isometric tension of circular muscle strips from Japanese White rabbits was examined. The NANC relaxation was induced by KCl (30 mM) in the presence of atropine (3 x 10(-6) M) and guanethidine (3 x 10(-6) M). The modifications of the NANC and sodium nitroprusside (SNP; 10(-5) M)-induced relaxation by the anesthetics were examined. The content of 3',5'-cyclic guanosine monophosphate (cGMP) was measured by radioimmunoassay. RESULTS: The KCl-induced relaxation was abolished by pretreating with tetrodotoxin (10(-6) M). The NANC relaxation was inhibited in the presence of N(G)-nitro-L-arginine (L-NNA; 3 x 10(-5) M), methylene blue (10(-6) M), apamin (10(-7) M), and glibenclamide (10(-5) M). The SNP-induced relaxation was inhibited by methylene blue but was not affected by tetrodotoxin, L-NNA, apamin, or glibenclamide. Ketamine (EC50 = 8.8 x 10(-5) M) and midazolam (EC50 = 4.8 x 10(-6) M) suppressed the NANC response in a concentration-dependent manner, leaving SNP-induced response unchanged. Thiopental altered neither of the relaxations. cGMP content was decreased in the presence of ketamine and midazolam. CONCLUSION: The NANC relaxation was mediated by nitric oxide and by low-conductance calcium- and adenosine triphosphate-sensitive potassium channels of smooth muscle. The modulation of the nitric oxide-cGMP pathway was related, at least in part, to the inhibitory actions of ketamine and midazolam on the NANC LES relaxation.

Anesthetics, Intravenous↗

PubMed2001

Bile leakage after hepatic resection.

OBJECTIVE: To identify the perioperative risk factors for postoperative bile leakage after hepatic resection, to evaluate the intraoperative bile leakage test as a preventive measure, and to propose a treatment strategy for postoperative bile leakage according to the outcome of these patients. SUMMARY BACKGROUND DATA: Bile leakage remains a common cause of major complications after hepatic resection. METHODS: Between January 1985 and June 1999, 781 hepatic resections without bilioenteric anastomosis were performed at the authors' institution. Perioperative risk factors related to postoperative bile leakage were identified using univariate and multivariate analysis. The characteristics of patients with intractable bile leakage and the effect of intraoperative bile leakage test were also examined. Management was evaluated in relation to the outcomes and the clinical characteristics of the patients with bile leakage. RESULTS: Bile leakage developed in 31 (4.0%) of 781 hepatic resections. This complication carried high risks for surgical death (two patients [6.5%] died). The stepwise logistic regression analysis identified high-risk surgical procedure, in which the cut surface exposed the major Glisson's sheath and included the hepatic hilum (i.e., anterior segmentectomy, central bisegmentectomy, or total caudate lobectomy), as the independent predictor of the development of postoperative bile leakage. None of the 102 cases in which an intraoperative bile leakage test was performed were subsequently complicated by postoperative bile leakage, and the preventive effect of the test was statistically significant. Patients with fisterographically demonstrable leakage from the hepatic hilum and with postoperative uncontrollable ascites had poor outcomes. CONCLUSION: Patients with bile leakage from the hepatic hilum and postoperative uncontrollable ascites tend to have a poor prognosis. Therefore, especially when a high-risk surgical procedure is performed in patients with liver cirrhosis, more careful surgical procedures and use of an intraoperative bile leakage test are recommended.

Bile↗

PubMed2001

Small graft for living donor liver transplantation.

OBJECTIVE: To evaluate the impact of graft size on recipients in living donor liver transplantation (LDLT) to establish a clinical guideline for the minimum requirement. SUMMARY BACKGROUND DATA: Although the minimum graft size required for LDLT has been reported to be 30% to 40% of graft volume (GV)/standard liver volume (SLV), the safety limit of the graft size was unknown. METHODS: A total of 33 cases of LDLT, excluding auxiliary transplantation, were reviewed with a minimum observation period of 4 months. The 33 patients were divided into three groups according to GV/SLV: medium-size graft group, small-size graft group, and extra-small graft group. The effect of GV/SLV on graft function, graft regeneration, and survival was evaluated. RESULTS: The overall patient survival rate was 94% at a mean follow-up of 15 months with a minimum observation period of 4 months. There were no statistically significant differences in postoperative bilirubin clearance, alanine aminotransferase, prothrombin time, and frequency of postoperative complications among the three groups. One week after transplantation, the regeneration rate (GV at 1 week/harvested GV) in the extra-small and small groups was significantly higher than that of the medium group. The graft and patient survival rates were both 100% in the extra-small group, 75% and 88% in the small group, and 90% and 95% in the medium group. CONCLUSIONS: Small-for-size grafts less than 30% of SLV can be used with careful intraoperative and postoperative management until the grafts regenerate.

Adult↗

PubMed2001

Number of lymph node metastases determined by presurgical ultrasound and endoscopic ultrasound is related to prognosis in patients with esophageal carcinoma.

OBJECTIVE: To analyze the impact on prognosis of the number of lymph node metastases detected by ultrasound and endoscopic ultrasound in patients with esophageal carcinoma. SUMMARY BACKGROUND DATA: Ultrasound and endoscopic ultrasound are useful for diagnosing tumor depth and lymph node metastasis in patients with esophageal carcinoma. However, the clinical significance of the number of lymph node metastases before surgery has not been elucidated. METHODS: The authors evaluated lymph node metastases using preoperative ultrasound and endoscopic ultrasound in 329 consecutive patients who underwent esophagectomy with lymphadenectomy. TNM classification and one-to-one comparison of lymph node metastasis was performed between the preoperative and histologic diagnosis. The number of lymph node metastases was subdivided into four groups: zero, one to three, four to seven, and eight or more. RESULTS: The accuracy of preoperative ultrasound and endoscopic ultrasound diagnosis exceeded 70% in each category of TNM classification. The incidence of lymph node metastasis determined by preoperative and histologic diagnosis was 69.0% (234/339) and 59.3% (201/339), respectively. The correlation between preoperative and histologic diagnosis was significant (P <.0001). According to the subdivision of number of lymph node metastases, the accuracy rates associated with nodal involvement of zero, one to three, four to seven, and eight or more were 83.8%, 59.7%, 43.3%, and 96.0%, respectively. The clinical outcome between ultrasound and endoscopic ultrasound diagnosis and histologic diagnosis in stage grouping was almost similar. The 5-year survival rates of patients with zero, one to three, four to seven, and eight or more lymph node metastases determined by ultrasound and endoscopic ultrasound were 53.3%, 33.8% 17.0%, and 0%, respectively. The differences among groups were statistically significant. The survival curves associated with preoperative and histologic diagnosis were similar. CONCLUSIONS: Not only the stage grouping of TNM classification but also the number of lymph node metastases determined by ultrasound and endoscopic ultrasound before surgery may be useful for predicting prognosis in patients with esophageal carcinoma.

Adult↗

PubMed2001

Chemotherapy-induced unconjugated hyperbilirubinemia caused by a mutation of the bilirubin uridine-5'-diphosphate-glucuronosyltransferase gene.

Chemotherapy for malignant neoplasms sometimes causes unconjugated hyperbilirubinemia in the absence of liver dysfunction. We analyzed the association of chemotherapy-induced hyperbilirubinemia with mutations of the bilirubin uridine-5'-diphosphate (UDP)-glucuronosyltransferase gene (UGT1A1) from two leukemic patients in whom chemotherapy resulted in a hyperbilirubinemic response. We isolated genomic DNA from peripheral blood samples and amplified UGT1A1 by polymerase chain reaction. The amplified DNA fragments were analyzed by direct sequencing. The genes of the two patients revealed an identical heterozygous missense mutation in exon 1 (211G-->A: G71R). This UGT1A1 mutation may be the basis of chemotherapy-induced unconjugated hyperbilirubinemia.

Adolescent↗

PubMed2001

Distribution and diversity of symbiotic thermophiles, Symbiobacterium thermophilum and related bacteria, in natural environments.

Symbiobacterium thermophilum is a tryptophanase-positive thermophile which shows normal growth only in coculture with its supporting bacteria. Analysis of the 16S rRNA gene (rDNA) indicated that the bacterium belongs to a novel phylogenetic branch at the outermost position of the gram-positive bacterial group without clustering to any other known genus. Here we describe the distribution and diversity of S. thermophilum and related bacteria in the environment. Thermostable tryptophanase activity and amplification of the specific 16S rDNA fragment were effectively employed to detect the presence of Symbiobacterium. Enrichment with kanamycin raised detection sensitivity. Mixed cultures of thermophiles containing Symbiobacterium species were frequently obtained from compost, soil, animal feces, and contents in the intestinal tracts, as well as feeds. Phylogenetic analysis and denaturing gradient gel electrophoresis of the specific 16S rDNA amplicons revealed a diversity of this group of bacteria in the environment.

Animals↗

PubMed2001

Effect of dietary conjugated linoleic acid on the in vivo growth of rat hepatoma dRLh-84.

We examined the effect of dietary conjugated linoleic acid (CLA) on the growth of injected hepatoma dRLh-84 in Donryu rats. After experimental diets containing 0% or 2% CLA were given to male Donryu rats for 3 wk, dRLh-84 cells were injected into the left lobe of the hepatic capsule, and the experimental diet was continued. The cells formed a solid tumor > or = 1 wk after the injection, and thereafter the tumor grew with feeding duration. In a morphological study, this tumor appeared to be a low-differentiated hepatoma, and there was no remarkable difference in the morphology of the tumor between 0% and 2% CLA groups. Tumor weight was significantly higher in the 2% CLA group than in the 0% CLA group throughout the feeding period after the injection. Serum glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase activities were significantly higher in 2% CLA-injected rats than in 0% CLA-injected rats at 3 wk after the injection. CLA upregulated acyl-CoA oxidase activity, especially 1 wk after the injection. However, dietary CLA did not activate carnitine palmitoyl transferase II, which is a rate-limiting enzyme in the mitochondrial beta-oxidation pathway. Natural killer cell activity in the spleen tended to be higher in injected rats, but a significant effect of dietary CLA was not recognized. Serum interferon-gamma and tumor necrosis factor-alpha levels were higher in injected than in sham rats. Moreover, these levels were higher in 2% CLA groups than in the respective 0% CLA groups.

Adipose Tissue↗

PubMed2001

Characterization of anti-myocardial autoantibodies in Japanese patients with dilated cardiomyopathy.

Few previous reports have comprehensively screened all the anti-myocardial autoantibodies (AMCA) in relation to other clinical profiles in patients with idiopathic dilated cardiomyopathy (IDC), so the present study used both immunohistochemistry (FITC) and immunoblotting (IB) for screening patients with IDC in order to characterize the clinical significance of AMCA. Sera were collected from 100 patients with IDC and age-matched 100 healthy control subjects (CTL). For FITC, an unfixed frozen section of human myocardium was used for the standard indirect immunofluorescence; for IB, total cardiac homogenates of the same myocardium were blotted to serum at 2 sets of dilution (1:200 and 1:10,000). The positive rates of AMCA detection for each method were as follows (IDC vs CTL); 39% vs 6% for FITC, 38% vs 4% for IB (1:200), and 10% vs 0% for IB (1:10,000). Fifty-nine patients with IDC and 8 CTL were positive for AMCA by either method, and 18 patients with IDC and 2 CTL were positive for AMCA by both methods. IB-positivity at 1:200 was an independent predictor by multiple logistic regression analysis of non-sustained ventricular tachycardias as well as left ventricular end-diastolic diameter and plasma norepinephrine concentration.

Adult↗

PubMed2001

Isolated and focal retrograde amnesia: a hiatus in the past.

Two cases of isolated retrograde amnesia were reported. Both showed the same clinical pattern in development and resolution of amnesia despite of different etiologies. Sudden insult to the brain (trauma in Case 1 and viral encephalitis in Case 2) caused concurrent antero- and retrograde amnesia. Fortunately both recovered from the anterograde amnesia completely. However, both were left with a period of postictal amnesia of a few months and retrograde amnesia of up to 14 months' duration. The analysis of their pattern of temporal evolution and dissolution of amnesia support the hypothesis that recently acquired episodic information requires a certain amount of constant activation for a certain period of time in order to be organized into a durable memory. The nature of this activation as well as its origin remains to be solved.

Accidents, Traffic↗

PubMed2001

Pneumatosis cystoides intestinalis treated with hyperbaric oxygen therapy: usefulness of an endoscopic ultrasonic catheter probe for diagnosis.

A 67-year-old woman was admitted to our hospital with a complaint of abdominal pain. Barium enema examination and colonoscopy showed numerous round polypoid lesions covered with normal mucosa in the area from the ascending colon to the splenic flexure. Endoscopic ultrasound examination with an ultrasonic catheter probe revealed a strong echo with distal acoustic shadowing in the third layer of the diseased colonic wall, which suggested the presence of gas in the submucosa. The gaseous cysts disappeared completely after hyberbaric oxygen therapy at 2 to 3 atmospheres absolute (60 minutes, twice a day) for 30 consecutive days.

Aged↗

PubMed2001

Effect of extracellular [Ca(2+)] on Ca(2+) release from sarcoplasmic reticulum in rat ventricular myocytes.

The effect of external [Ca(2+)] ([Ca(2+)](o)) on Ca(2+) release from the sarcoplasmic reticulum (SR) was examined with rested-state twitches in rat ventricular myocytes. The magnitude of transient rise of intracellular [Ca(2+)] ([Ca(2+)](i)) relative to the resting one, F/F(o), as measured with fluo-3, was 1.75+/-0.07 (mean+/-SEM, n=9) and 1.86+/-0.13 (n=9) at 0.3 and 1.8 mM [Ca(2+)](o), respectively; the difference was insignificant. The time from onset to peak and the rate of rise of the [Ca(2+)](i) transient were 0.107+/-0.017 s (n=9) and 18.8+/-3.38 F/F(o)/s, respectively, at 0.3 mM [Ca(2+)](o), they were 0.064+/-0.005 s (n=9) and 31.1+/-0.03 F/F(o)/s, respectively, at 1.8 mM [Ca(2+)](o). The difference in the corresponding values at the two [Ca(2+)](o) was significant (t-test, p<0.05). The half decay time of the [Ca(2+)](i) transient was 0.217+/-0.016 s (n=8) at 0.3 mM [Ca(2+)](o) and was similar to the value of 0.230+/-0.022 s (n=8) at 1.8 mM [Ca(2+)](o), indicating that the rate of decrease of [Ca(2+)](i) is independent of the [Ca(2+)](o). The duration of action potential was similar at 0.3 and 1.8 mM [Ca(2+)](o) as examined with papillary muscle. The results suggest that a lowering of [Ca(2+)](o), i.e., reducing the Ca(2+) influx, slows the rate of Ca(2+) release from the SR fully loaded with Ca(2+) with little effect on the total amount of the Ca(2+) release. An instantaneous relationship between the [Ca(2+)](i) and the myocyte shortening at 0.3 and 1.8 mM [Ca(2+)](o) suggested that the time course of unloaded contraction is related not only to the magnitude, but also to the rate of rise of [Ca(2+)](i).

Animals↗

PubMed2001

Intracellular [Ca(2+)] transients in Ca(2+) wave in single rat ventricular myocyte.

Ca(2+) release from the sarcoplasmic reticulum (SR) in heart muscle grades depending on Ca(2+) influx in the physiological twitch; Ca(2+( wave results from regenerative Ca(2+) release from the SR. To examine if the Ca(2+) release from the SR in the Ca(2+) wave takes a duration similar to the physiological one, a transient rise of intracellular [Ca(2+)] ([Ca(2+)](i) transient) was recorded during both a propagating Ca(2+) wave and an electrically evoked twitch with single rat ventricular myocytes, using a laser scanning confocal microscope. Care was taken to record the fluo-3 fluorescence from a segmental region with little lateral movement, especially during a propagating Ca(2+) wave. During a typical Ca(2+) wave, the time-to-peak (TP) and the half-width (HD) of the averaged [Ca(2+)](i) transient were 161 and 253 ms respectively, but they were 76 and 145 ms during an electrically evoked twitch. The difference in the duration between the two types of [Ca(2+)](i) transients could not be accounted for by modification of duration of [Ca(2+)](i) transient by possible asynchronous Ca(2+) release from the SR during a Ca(2+) wave, suggesting that the regenerative Ca2+) release from the SR in the Ca2+) wave occurs more slowly than the physiological one in rat ventricular myocytes.

Animals↗