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Biomedical subjects

K Obata

Publications and source records attributed to K Obata.

At least 271 records · Page 15Linked to original sources
PubMed1984

An international study of smoking and bladder cancer.

The effects of smoking cigarettes and other forms of tobacco on the development of cancer of the lower urinary tract (bladder cancer) were evaluated in Boston, Massachusetts, Manchester, United Kingdom and Nagoya, Japan. Population-based series of incident cases and controls were identified and interviewed in each area. The present analyses were based on 592 cases and 533 controls in Boston, 553 cases and 731 controls in Manchester, and 290 cases and 588 controls in Nagoya. Smokers of cigarettes had about twice the incidence of bladder cancer as nonsmokers. In men the strength of the association between cigarette smoking and bladder cancer was similar in the 3 study areas. The strength of the association varied somewhat from area to area among women. Bladder cancer risk increased with frequency of cigarette smoking and with deep inhaling. In Boston men who smoked 2 or more packs of cigarettes per day and inhaled deeply had nearly 7 times the risk of nonsmokers. Ex-smokers had a level of risk between that of current smokers and nonsmokers. However, there was no clear relationship between risk and age at which cigarette smoking began, time since discontinuation among ex-smokers and use of filters. Over-all, there was little difference in bladder cancer risk between men who had and who had not smoked pipes but pipe smoking did appear to be associated with risk among men who had never smoked cigarettes. Cigar smoking was unrelated to bladder cancer.

Adolescent↗
PubMed1984

Developmental changes of chick cerebellar cortex revealed by monoclonal antibodies.

Immunohistochemistry studies of the embryonic and newly hatched chick cerebellum were performed with 13 monoclonal antibodies (MAbs) raised against the embryonic chick optic nerve and a MAb which binds to cell nuclei. Neural MAbs differentially stained Purkinje cells, the external granular layer, molecular layer, internal granular layer, climbing fibers, basket cell axons, Bergmann glia and Ramón y Cajal's ansiform fibers. At the different developmental stages each component responded to MAbs differently. For example, staining of Purkinje cells with MAbs 23C10, 82E10 and 94C2 appeared on day 11 of incubation and disappeared sequentially after day 18. These results reveal molecular heterogeneity not only in cerebellar neurons but also at various developmental stages.

Animals↗
PubMed1984

Monoclonal antibodies demonstrate regional specificity in the spinal funiculi of the chick embryo.

To explore the extent and significance of chemical diversity of neurons, monoclonal antibodies were generated that bind to the chick embryonic central nervous system with varying degrees of regional specificity. Mice were immunized against a homogenate of optic nerves from 8-day chick embryos. Antibody was screened by an indirect fluorescence immunohistochemical method using frozen sections of embryonic neural tissues. From 3 fusion experiments, 58 lines of hybrydoma were cloned. Twenty-three monoclonal antibodies were studied in detail, and here reported, for their characteristic staining patterns in the spinal cord of 6-day embryos. The majority of the antibodies bound preferentially to different subregions of spinal funiculi, in which glial elements are still undeveloped. At least 6 subregions could be distinguished in the funiculi, probably corresponding to the developing spinal tracts. For 8 of the antibodies, immunoreactive polypeptides were identified in an electrophoretic analysis.

Animals↗
PubMed1983

Combination chemotherapy including adriamycin for advanced transitional cell carcinoma of the urinary tract.

Thirty-three patients with advanced transitional cell carcinoma of the urinary tract (23 bladder cases, 8 ureter cases, and 2 renal pelvis cases) were treated by three-drug combination chemotherapy using two protocols (protocol I: Adriamycin 50 mg/m2, cyclophosphamide 500 mg/m2, and 5-fluorouracil 500 mg/m2, protocol II: Adriamycin 50 mg/m2, cyclophosphamide 500 mg/m2, and cis-platinum 50 mg/m2). Protocol I induced responses in three of 19 patients (16%), (1 complete response, 2 partial responses), and protocol II (I complete response, 4 partial responses) in five of 14 patients (36%). The overall response rate was 24%. The duration of response was relatively short (median duration 5.1 months). The combination therapy was relatively well tolerated except in three patients, including two mortalities. In our study, three-drug combination chemotherapy with Adriamycin, especially that including cis-platinum, was effective against transitional cell carcinoma of the urinary tract, but the results were not completely satisfactory.

Adult↗
PubMed1983

Survival of HRP-labeled spinal motoneurons of chick embryo in tissue and cell cultures.

Motoneurons in the lumbar spinal cord of chick embryos 6 days old, the age when their cell death starts, were labeled in vivo by retrograde axonal transport of horseradish peroxidase (HRP) and then cultured as cord fragments or isolated cells. In Eagle's minimum essential medium with no additives, spinal cord cells survived well, but among them, the survival of HRP-labeled motoneurons was poor. Muscle-conditioned medium and a mixture of horse serum (HS) and whole chick embryo extract (CEE) promoted motoneuron survival in both suspension culture of spinal cord fragments and monolayer culture of spinal cord cells. It appeared that multiple factors may be involved in the increased extent of motoneuron survival, because HS or CEE alone showed only weak activity in contrast with the combination of HS and CEE.

Animals↗
PubMed1983

Identification of a membrane protein induced concurrently with cell filamentation by cyclic AMP in an Escherichia coli K-12 fic mutant.

A membrane protein with a molecular weight of 40,000 (40K protein) was induced concurrently with cell filamentation by cyclic AMP (cAMP) in a fic mutant. In the crp mutant and the wild-type strain, cell filamentation by cAMP was not observed, and the 40K protein was not induced. Induction of the 40K protein is regulated by the cAMP-cAMP receptor protein complex and is closely related to cell filamentation by cAMP in the fic mutant.

Cell Membrane↗
PubMed1982

Histologic features of bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan.

Histologic characteristics of bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan, were evaluated. In each of these areas broadly-based series of cases were assembled during a collaborative case-control study. The present analysis was based on 589 cases in Boston, 484 cases in Manchester, and 241 cases in Nagoya. A single pathologist reviewed a slide of the primary tumor without reference to identifying information or other data. The primary histologic type of nearly all tumors was transitional-cell, and there was little variation in the proportion of transitional-cell tumors among the study areas. Nor was there much variation in the distribution of histologic grade, the proportion of tumors showing submucosal invasion, or the proportion of tumors with a papillary surface. Age at diagnosis was strongly correlated with histologic grade. The proportion of grade III (most malignant) tumors was about twice as high among patients 80 years of age and over as among those aged less than 50. An apparent association between age and submucosal invasion was explained in large part by the relationships of histologic grade to submucosal invasion and to age. Other histologic features had only weak and inconsistent relations with age. None of the features evaluated showed consistent associations with history of cigarette-smoking or with sex.

Adenocarcinoma↗
PubMed1982

Effects of serum, tissue extract, conditioned medium, and culture substrata on neurite appearance from spinal cord explants of chick embryo.

The effects of serum, tissue extracts, conditioned medium, (CM), and culture substrata on neurite appearance from spinal cord explants of 6- to 8-day-old chick embryos were investigated. In Eagle's minimum essential medium (MEM) with no supplement neurites from explants did not appear on collagen coating but on polyornithine coating (PORN). It is concluded that cell-to-substratum interaction is important in neurite appearance. CM, serum and tissue extract potentiated neurite appearance, but their activities were highly dependent on the coating. The amount of collagen was also crucial. On collagen, neurite appearance was observed only when promoting substances were present. CM and serum contained at least two components; one affected neurite appearance after deposition on collagen and the other affected neurite appearance when present in the culture medium. The former was included also in tissue extracts. Both of adsorbable and non-adsorbable components from any origin were necessary for effective induction of neurite appearance. Heat treatment and dialysis differentiated these active components. On PORN, CM highly potentiated neurite appearance. The activity of the CM was reproduced by its low molecular weight fraction. Serum also promoted neurite appearance, but to a lesser extent than CM. The effect of tissue extract was not remarkable.

Animals↗
PubMed1982

Survival and neurite growth of chick embryo spinal cord cells in serum-free culture.

Cell survival and neurite growth were investigated in serum-free spinal cord cell cultures on polyornithine coating (PORN). Cells were obtained from 6- or 7-day-old chick embryos. Isolated spinal cord cells required promoting factors for their survival and neurite growth. The survival-promoting factors were initially present in spinal cord cells. High density cultures, co-cultures with spinal cord explants, and spinal cord extract promoted survival of isolated spinal cord cells in MEM with no additives. Other tissue extracts (brain, liver, heart and skeletal muscle), serum, and serum-free conditioned medium (SF-CM) of muscle or glioma C6 cells also promoted survival. The active substances in the brain extract and SF-CM were shown to be protein and were separated into 3 fractions (approximately molecular weight 150,000, 70,000, 40,000) by gel filtration chromatography. Survival and neurite growth were suggested to be promoted by different factors because: (1) survival was promoted by both tissue extract and SF-CM, but neurite growth was promoted only by SF-CM; (2) the neurite growth-stimulating activity of SF-CM was lost following dialysis and heat (100 degrees C, 2 min) treatment; however, the survival-promoting activity was not. It was also suggested that spinal cord cells produce neurite growth promoting factors, but did not initially contain these factors.

Animals↗
PubMed1982

Artificial sweeteners and bladder cancer in Manchester, U.K., and Nagoya, Japan.

We have evaluated the relation between cancer of the lower urinary tract ("bladder cancer") and the use of artificial sweeteners, by means of case-control studies in Manchester, U.K., and Nagoya, Japan, areas where extensive use occurred 30-40 years ago. In each area, a broadly based series of cases (555 in Manchester, 293 in Nagoya) was interviewed and a series of controls (735 in Manchester, 589 in Nagoya) chosen from the general population. A history of use of sugar substitutes primarily saccharin, was not associated with an elevated risk of bladder cancer in either study area. Risk of bladder cancer did not increase regularly with frequency or duration of use of sugar substitutes. Data on dietetic beverages were not obtained in Nagoya. This exposure was not associated with a greater risk of bladder cancer in Manchester. The results of this study suggest that use of artificial sweeteners confers little or no risk of bladder cancer.

Adult↗
PubMed1982

Altered developmental changes of neuromuscular junction in hypo- and hyperthyroid rats.

1. Effects of thyroid hormone on the development of neuromuscular junctions (n.m.j.s.) were investigated electrophysiologically in the diaphragms (sternal region) of normal, hypo- and hyperthyroid rats from the age of birth (day 0) to day 35.2. Hypothyroidism in new-born rats was induced either by daily administration of propylthiouracil to mothers or by subcutaneous injection of 150 muCi (131)I on day 1. Hyperthyroidism was induced by daily injection of thyroxine.3. In normal rats up to day 10, muscle fibres were innervated polyneuronally. By day 20, multiple innervation was eliminated and muscle fibres received only a single input. In hypothyroid rats elimination of polyneuronal innervation was retarded by 5-8 days, while in hyperthyroid rats the elimination was accelerated by 2-3 days.4. The frequency of miniature end-plate potentials (m.e.p.p.s) in normal rats increased from one per 40 sec on days 0-5 to 1/sec on days 25-35. The m.e.p.p. frequency in hypothyroid rats was 25-65% of that in normal rats of the same age. In hyperthyroid rats the m.e.p.p. frequency was normal up to day 18 but subnormal afterwards. The duration of m.e.p.p. measured on day 22-23 was slower in hypothyroid rats and faster in hyperthyroid rats, relative to m.e.p.ps in normal rats.5. The sensitivity to acetylcholine (ACh) at extrajunctional regions in normal rats was about 100 mV/nC at birth and declined to 1 mV/nC by day 26. In hypothyroid rats, the ACh sensitivity was as high as 30 mV/nC on day 26; in hyperthyroid rats, ACh sensitivity on day 26 was undetectable.6. With pairs of nerve stimuli (applied at a 50 msec interval), the second end-plate potential was facilitated until day 10 and depressed after day 16 in normal rats. This shift from facilitation to depression during development was not altered in either hypo-or hyperthyroid rats.7. It is concluded that the lack and excess of thyroid hormone retards and facilitates the development of n.m.j.s. respectively. Possible mechanisms for this altered development are discussed.

Acetylcholine↗
PubMed1982

Coffee drinking and cancer of the lower urinary tract.

The relation of coffee drinking to the incidence rate of cancer of the lower urinary tract ("bladder cancer") was evaluated. Broadly based series of cases and series of controls drawn from the general population of each area were assembled and interviewed in Boston, Massachusetts (587 cases, 528 controls), Manchester, England (541 cases, 725 controls), and Nagoya, Japan (289 cases, 586 controls). Compared to drinkers of an average of less than 1 cup of coffee per day, those who drank more had a relative risk of bladder cancer estimated as 1.0 (0.8-1.2, 95% confidence interval). With adjustment for cigarette smoking habits, only small and irregular changes in risk were seen with increasing frequency of coffee consumption. Duration of coffee drinking showed little relation to risk of bladder cancer may be due to incomplete control of the effect of cigarette smoking. If there is a true association of coffee drinking and bladder cancer it is likely to be weak.

Age Factors↗
PubMed1981

Stimulus-dependent labeling of cultured ganglionic cell with [14C]2-deoxyglucose.

We prepared cultures of dissociated cells from the ciliary (CG) and dorsal root ganglion (DRG) of 10--12-day-old chick embryos, and applied [14C]2-deoxyglucose ([14C]2-DG) to the cultured cells to examine the effects of stimulation on the labeling with [14C]2-DG at the single cell level. Electrical current stimulation increased [14C]2-DG uptake in CG and DRG neurons. The increase depended on frequency of the stimulation. These effects were potentiated by the application of tetraethylammonium, but suppressed by tetrodotoxin. Externally applied potassium ions increased the [14C]2-DG uptake in the CG cell, depending logarithmically on the concentration of applied KCl. The concentration-dependent increase agreed with potassium effect on the equilibrium potential. For CG cells, acetylcholine (ACh), glutamate, gamma-aminobutyric acid (GABA) and glycine induced remarkable increases of the [14C]2-DG uptake, while dopamine did not induce any change. For DRG cells, GABA and glycine facilitated the [14C]2-DG uptake, while ACh, glutamate and dopamine did not have any significant effects on it. These facilitatory actions of neurotransmitters on the [14C]2-DG uptake are mostly consistent with the excitatory effects of the substrates on both CG and DRG cells in culture. The results suggest that the [14C]2-DG uptake in single cells is intimately correlated with action potential generation and change in the testing potential.

Animals↗
PubMed1981

Requirements for growth of neurites from embryonic chick cerebellum in culture.

Embryonic chick cerebella were cut into pieces and cultured under various conditions. Neurites were extended actively to collagen gel for a week or so and then degenerated. The neurite growth for the first two days was similar, also in the serum-free medium. Among 15 substances tested, insulin and cyclic AMP facilitated the growth.

Animals↗