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Biomedical subjects

K Tajima

Publications and source records attributed to K Tajima.

At least 289 records · Page 16Linked to original sources
PubMed1993

Prediction of protein secondary structures by a neural network.

We have studied the prediction of globular protein secondary structures by neural networks. Protein secondary structures are allocated to amino acid residues using Kabsch and Sander's dictionary of protein secondary structures and the neural network is taught the protein secondary structures. The input layer of the neural network allows sequences of residues including 20 amino acids, chain break, B, X and Z. We consider classifying secondary structures into groups of 3, 4 and 8. In each case, we calculate the percentage of correct predictions. We discuss the effect of overlearning on the protein secondary structure prediction. In addition, we include the application of a neural network with a modular architecture to prediction of protein secondary structures. We compare the results from neural networks with a modular architecture and with a simple three-layer structure.

Algorithms↗
PubMed1993

Peopling of the Americas, founded by four major lineages of mitochondrial DNA.

Nucleotide sequence analysis of the major noncoding region of human mitochondrial DNA from various races was extended with 72 Native Americans from 16 different local populations (nine populations from Chile, four from Colombia, and one each from Brazil and from Maya and Apache Indians). The sequences were determined directly from the polymerase chain reaction products. On the basis of a comparison of the 482-bp sequences in the 72 Native Americans, 43 different types of mitochondrial DNA sequences were observed. The nucleotide diversity within the Native Americans was estimated to be 1.29%, which is slightly less than the value of 1.44% from the total human population including Africans, Europeans, and Asians. Phylogenetic analysis revealed that most Native American lineages are classified into four major distinct clusters. Individuals belonging to each cluster share at least two specific polymorphic sites that are nearly absent in other human populations, indicating a unique phylogenetic position of Native Americans. A phylogenetic tree of 193 individuals including Africans, Europeans, Asians, and Native Americans indicated that the four Native American clusters are distinct and dispersed in the tree. These clusters almost exclusively consist of Native Americans--with only a few Asians, if any. We postulate that four ancestral populations gave rise to different waves of migration to the New World. From the estimated coalescence time of the Asian and Native American lineages, we infer that the first migration across the Bering landbridge took place approximately 14,000-21,000 years ago. Furthermore, sequence differences in all pairwise comparisons of Native Americans showed a bimodal distribution that is significantly different from Poisson. These results suggest that the ancestral Native American population underwent neither a severe bottleneck nor rapid expansion in population size, during the migration of people into the Americas.

Americas↗
PubMed1993

Protective effects of raw vegetables and fruit against lung cancer among smokers and ex-smokers: a case-control study in the Tokai area of Japan.

In a hospital-based case control study, the protecting effects of fruit, raw and green vegetables against lung cancer risk among male smokers were studied in 282 cases and the same number of controls. The current smokers showed a 6.61-fold increased risk of lung cancer. The odds ratio (OR) declined markedly with starting age of smoking habit and increased markedly with number of cigarettes smoked per day. The ex-smokers showed a 3.56-fold increased risk of lung cancer. The ORs gradually decreased with years passed since cessation of smoking. In the single factor analysis, significant protective effects of fruit, raw vegetables, green vegetables, lettuce and cabbage against lung cancer were found. The risk for all lung cancer decreased to 0.45 (95% confidence intervals (CI) 0.30-0.67), 0.64 (95% CI 0.43-0.97) and 0.44 (95% CI 0.26-0.73) with increment of intake frequency of fruit, raw and green vegetables respectively. The OR for lung cancer decreased to 0.41 (95% CI 0.24-0.72) and 0.56 (95% CI 0.32-0.99) with increasing intake frequency of fruit and raw vegetables among current smoking males. Lettuce and cabbage showed protective effects against lung cancer, and the OR for risk of lung cancer decreased to one-half among the high intake frequency group. The risk of lung cancer among current smokers declined markedly with increasing intake of lettuce and cabbage. A similar effect was observed among ex-smokers and non-smokers, but there was no statistical significance. In the multivariate analysis, fruit and raw vegetables showed the strongest protective effects against lung cancer among current smokers (P = 0.01). Among ex-smokers, the protective effect of fruit is also statistically significant (P = 0.03). These results suggest that fruit and raw vegetables may play an important role in protecting smokers from lung cancer.

Adult↗
PubMed1993

Artificial pneumothorax as a risk factor for development of pleural lymphoma.

An etiologically important role of chronic tuberculous empyema for development of pleural lymphocytic lymphoma of B-cell type has been suggested. To examine risk factors for development of pleural lymphoma in patients with chronic tuberculous empyema, a case-control study was carried out. Onset age of lung tuberculosis and empyema, presence of chemotherapy, surgical treatment, extent of empyema, presence of fistula, history of smoking, and height and weight of patients at first admission were compared in patients with empyema alone (70 controls) and empyema complicated with lymphoma (42 cases): the date of birth and sex were matched by group. The patients receiving artificial pneumothorax showed a significant increase in risk for development of pleural lymphoma (relative risk = 4.92, P < 0.05). We could not find any report describing development of pleural neoplasias in patients with chronic empyema receiving surgical resection of pleural pyogenic membrane. From these findings, it is suggested that artificial pneumothorax left chronic non-healing inflammation in the pleural cavity, which resulted in development of pleural lymphoma.

Adult↗
PubMed1993

Identification of human T cell leukemia virus type IIb infection in the Wayu, an aboriginal population of Colombia.

Human T cell leukemia virus type II (HTLV-II) is endemic in a number of native American populations and high rates of infection have also been demonstrated in intravenous drug abusers (IVDAs). Studies of virus isolates in the latter population have shown the existence of two closely related subtypes of the virus, HTLV-IIa and HTLV-IIb. To characterize the viruses present in native Americans, we analyzed by nucleotide sequence analysis the proviruses from the Wayu, an aboriginal population residing in Colombia, South America. The results showed HTLV-IIb infection in this population, and also demonstrated remarkable conservation of sequence when compared to the proviruses in IVDAs.

Base Sequence↗
PubMed1993

Effects of isoquinolinesulphonamide compounds on multidrug-resistant P388 cells.

The effects of eight isoquinolinesulphonamide compounds on resistance to vinblastine in adriamycin-resistant mouse leukaemia cells (P388/ADR) which overexpress the relative molecular weight (M(r)) 140 kDa P-glycoprotein in the plasma membrane were investigated. N-[2-(Methylamino)ethyl]-5-isoquinolinesulphonamide (H-8) and N-(2-aminoethyl)-5-isoquinolinesulphonamide (H-9) did not reverse vinblastine resistance. N-[2-[N-[3-(4-Chlorophenyl)-2-propenyl]amino] ethyl]-5-isoquinolinesulphonamide (H-86) and N-[2-[N-[3-(4-chlorophenyl)-1-methyl-2-propenyl] amino]ethyl]-5-isoquinolinesulphonamide (H-87) caused accumulation of intracellular vinblastine and inhibition of vinblastine efflux from the cells and reversed the resistance. Addition of an aminoethyl group to the nitrogen atom of the sulphonamide group (W-66) or a formyl group at the terminal amino group (H-85) of H-86 reduced those activities. Conversion of the chlorophenyl group of H-87 to pyridinyl (H-31) or furanyl (H-34) markedly decreased activities against the drug resistance. The activity against vinblastine accumulation closely correlated with the apparent partition coefficient of compounds. These compounds dose-dependently inhibited photoaffinity labelling of a photosensitive analogue of vinblastine, N-(p-azido-(3-[125I)salicyl)-N'-beta-aminoethyl-vindesine ([125I]NASV), and there was a good correlation between inhibition of [125I]NASV-photolabelling and hydrophobicity. Although these isoquinolinesulphonamides inhibited protein kinase A with different magnitudes, this activity did not correlate with the effect on the drug resistance. These results indicate that isoquinolinesulphonamide compounds with a hydrophobic group interact with antitumour drugs on P-glycoprotein and reverse multidrug resistance without involvement of their activity on protein kinase A.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Relative frequencies of G (VP7) and P (VP4) serotypes determined by polymerase chain reaction assays among Japanese bovine rotaviruses isolated in cell culture.

The relative frequencies of both the G (VP7) and P (VP4) serotypes of 40 bovine rotaviruses isolated in cell culture from diarrheic calves in Japan between January 1983 and February 1991 were determined by recently developed polymerase chain reaction assays. Isolates with G serotype 6 and P serotype 5 (UK-like strains) were most frequently found (42.5%) followed by isolates with G6P11 (17.5%), G6P1 (10%), or G10P5 (10%). Isolates with G10P11 (B223-like strains) were least frequently found (7.5%). The presence of various combinations of G and P serotypes suggests frequent reassortment in nature among bovine rotaviruses.

Animals↗
PubMed1993

The inhibitory effect of noradrenaline on thyrotrophin-stimulated 3,5,3'-tri-iodothyronine and thyroxine release is mediated through a Ca(2+)-dependent process in the thyroid gland of the mouse.

We examined the effect of noradrenaline on the release of 3,5,3'-tri-iodothyronine (T3) and thyroxine (T4) from perifused mouse thyroid. Noradrenaline suppressed the thyrotrophin (TSH)-stimulated release of T3 and T4. The addition of prazosin, which is a specific alpha 1 antagonist, or the depletion of Ca2+ from the perifusion buffer completely abolished the inhibitory effect of noradrenaline on TSH-stimulated T3 and T4 release. Noradrenaline did not inhibit TSH-stimulated cyclic adenosine 3',5'-monophosphate (cAMP) release in the presence of 3-isobutyl-1-methylxanthine (IBMX), which inhibits both cAMP-specific and calmodulin-sensitive phosphodiesterases. Noradrenaline significantly suppressed the TSH-stimulated release of T3 and T4 in the presence of IBMX. These results suggest that the inhibitory effect of noradrenaline on TSH-stimulated T3 and T4 release is not mediated through a cAMP-dependent process or the activation of a calmodulin-sensitive phosphodiesterase, and that this inhibition is mediated through a Ca(2+)-dependent process regulated by the alpha 1-adrenergic system in the mouse thyroid.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Differences in clinicopathological characteristics and major prognostic factors between B-lymphoma and peripheral T-lymphoma excluding adult T-cell leukemia/lymphoma.

A total of 541 consecutive patients treated between 1975 and 1985, 449 with B-lymphoma and 92 with peripheral T-lymphoma, excluding adult T-cell leukemia/lymphoma (ATL), termed peripheral non-ATL T-lymphoma, were analysed. Clinicopathological features that were predominantly associated with B-lymphoma were low and intermediate grades (defined by the Working Formulation), diffuse large cell type, stage II disease, bulky disease, favourable extranodal sites that are defined as a group of primary tumors such as the eye, Waldeyer's ring, thyroid, and stomach, while other features predominantly associated with peripheral non-ATL T-lymphoma were high grade pathology, diffuse mixed-cell and immunoblastic type, systemic "B" symptoms, poor performance status (PS), generalized lymphadenopathy, involvement of organs such as liver, skin, and nose, leucocytosis, and a high levels of serum alkaline phosphatase. The survival curve for B-lymphoma was better (P < 0.01) than that for peripheral non-ATL T-lymphoma. Multivariate analysis revealed that the major prognostic factors were pathology, stage, and primary site for B-lymphoma, while stage, PS, and total protein levels were important for peripheral non-ATL T-lymphoma. These results indicate that B- and peripheral non-ATL T-lymphomas appear to have different biological characteristics.

Adult↗
PubMed1993

Effect of an ultraviolet light-activated coating material on reduction of the leaching of methyl methacrylate and formaldehyde from denture acrylic resins.

Effect of glazing with an ultraviolet light-activated coating material on reduction of the leaching of methyl methacrylate and formaldehyde from denture acrylic resins was quantitatively evaluated. Disks prepared from auto-polymerized resins were painted with the material and radiated with ultraviolet light. The disks were immersed in artificial saliva and the concentrations of methyl methacrylate and formaldehyde leached were determined by high-performance liquid chromatography and flow injection analysis. Compared to untreated controls, the glaze significantly decreased concentrations of both leachable substances. Treatment with an ultraviolet light-activated coating material is effective in suppressing the leaching of methyl methacrylate and formaldehyde from acrylic resins as well as in smoothing the denture surfaces.

Acrylic Resins↗
PubMed1993

Effects of long- and medium-chain triglycerides on amino acid uptake in rat intestinal brush border membrane vesicles.

1. Uptake of L-leucine, L-phenylalanine, L-proline and L-lysine into brush border membrane vesicles from rats fed either a medium-chain triglyceride (MCT) or a long-chain triglyceride (LCT) diet was studied under conditions of the presence of absence of a Na+ gradient. 2. From the results of initial rate, Na(+)-dependent transport in LCT feeding were lower than in feeding MCT. The Na(+)-independent transport did not vary in either group except for L-lysine uptake. 3. For L-leucine, L-phenylalanine and L-proline in Na+ dependence, kinetic analysis revealed 4-6-fold smaller Vmax values in LCT group than in MCT group. L-Lysine in Na(+)-independent transport was 10-fold lower in LCT group than in MCT group. The Km values were not affected by feeding the LCT or MCT diet. 4. It is clear that amino acid transport is regulated by different types of dietary fat. We consider that the alteration of transport activity is attributable to the changes in number of membrane-bound transport carriers but not to their affinity.

Amino Acids↗
PubMed1993

[Preliminary study of HTLV-I seroprevalence in Chilean Indian populations].

Aiming to seek the origin and define the prevalence of HTLV-1 infections, 464 blood samples from aboriginal populations proceeding from isolated regions of the north and south of Chile were studied. Antibodies against HTLV were measured with agglutination tests and confirmed with immuno-fluorescence and Western Blotting. Seven out of 107 (6.5%) blood samples from Atacama indians, 2 out of 202 (1%) from Mapuche indians and 3 out of 155 (1.9%) from Huilliche aborigines were positive. These results highlight an important presence of the virus in indigenous populations, specially in the extremes of the country. These findings could suggest an indigenous (mongoloid) origin of HTLV-1 in Chile, specially in Chiloe, where apparently there has been no contact with african or japanese populations, that could be the origin of the contamination.

Adolescent↗
PubMed1993

[Japan Clinical Oncology Group for cooperative cancer clinical trials and role of the statistical center in the management of cancer clinical trials].

In 1978, clinical investigators decided to collaborate on clinical trials through a "cooperative group" mechanism in order to promote multidisciplinary treatment of cancer under the auspices of a Grant-in-Aid for Cancer Research from the Ministry and Health and Welfare. This cooperative study group was formally renamed in 1990 and became "The Japan Clinical Oncology Group (JCOG)," and its Statistical Center was housed in the National Cancer Center Hospital. This paper introduces various JCOG activities and the role of the Statistical Center.

Clinical Protocols↗
PubMed1993

[Operative management of aortic arch aneurysm using selective cerebral perfusion].

Hypothermic circulatory arrest for aortic arch surgery can be tolerated for a limited period of time. To avoid this disadvantage, we used hypothermic cardiopulmonary bypass (CPB) with selective cerebral perfusion (SCP), in which the femoral artery, right axillary artery (RAA) and left common carotid artery (LCCA) were separately cannulated and perfused by individual pump heads. The pressures of bilateral superficial temporal arteries were monitored to maintain the cerebral perfusion pressure at 50 mmHg. The flow of RAA and LCCA was maintained at 5 ml/min/body weight kg, the pressure of each superficial temporal artery at 50 mmHg and the nasopharyngeal temperature at 20 degrees C. To perform the "open distal repair", the CPB was stopped while cerebral perfusion was maintained. Between 1986 and 1991, 20 patients were operated on with this method. Mean duration of SCP was 169 minutes (73 to 210), and mean duration of CPB was 290 minutes (136 to 472). There was no intraoperative death. Operative mortality rate within 30 days after surgery was 10% (2/20). Neurological sequelae occurred in one patient with emergency operation for acute aortic dissection, into LCC of whom we had trouble in inserting a cannula. It was considered that SCP could be performed for at least 2 hours with the results of good cerebral protection.

Aged↗
PubMed1993

[Uveitis in human T-lymphotropic virus type I (HTLV-I) carriers--1. A seroepidemiological study].

A seroepidemiological study was carried out to find out if human T-lymphotropic virus type I (HTLV-I) was closely associated with uveitis in two hospitals: one in an area where HTLV-I was highly prevalent (Miyakonojo, Miyazaki) and the other in an area where HTLV-I was less prevalent (Kurume). In the highly prevalent HTLV-I area, the seroprevalence in patients with idiopathic uveitis (78/206, 37.9%) was significantly higher than in patients with non-uveitic ocular diseases (73/380, 19. 2%) or in patients with uveitis with defined etiologies (8/80, 10.0%). A more striking finding was that the seroprevalence in the younger group (20-49 years) with idiopathic uveitis in the area was 40/82 (48.8%), but only 9/114 (7.9%) in the other two reference groups. The odds of contracting idiopathic uveitis for HTLV-I infected persons was estimated at 11.0 in the younger group, and 2.0 in the older group. Similar observations were recorded even in the less prevalent area (Kurume). These data thus suggest that HTLV-I infection is a risk factor for idiopathic uveitis.

Adult↗
PubMed1993

[Safe and easy surgical atrial septectomy for congenital heart diseases].

Surgical atrial septectomy using a Kerrison clamp, which is used in neurosurgery, was done in four elder infants without extra-corporeal circulation. Two (6 and 4 months old) had an atresia of left atrio-ventricular valve with small atrial septal defect, one (8 months) had a transposition of great arteries with closing multiple ventricular septal defects, and one had a pure pulmonary atresia. A purse string suture was put on the right atrial appendage and the clamp in a closing position was inserted into the left atrium through the appendage and the atrial septum. The edge of the atrial septal defect and/or patent foramen ovale was hooked by pulling it slowly. It was closed strictly and pulled out together with a resected atrial specimen. This technique is safer and easier than the Blalock-Hanlon technique and atrial septectomy under extra-corporeal circulation for elder infants for whom balloon atrial septostomy is difficult to be done.

Cardiac Surgical Procedures↗