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Biomedical subjects

T Kohama

Publications and source records attributed to T Kohama.

At least 73 records · Page 4Linked to original sources
PubMed1989

Effect of cerebellectomy on reflex micturition in the decerebrate dog as determined by urodynamic evaluation.

The effect of cerebellectomy on reflex micturition in the decerebrate dog was investigated by cystometric and striated urethral sphincter EMG studies. Before and after cerebellectomy, reflex micturition consisting of bladder contraction and spasmodic contraction of the striated urethral sphincter occurred when a critical degree of filling was reached. Cerebellectomy showed no influence on the striated urethral sphincter EMG activity. However, cerebellectomy produced a significant decrease in threshold volume and threshold pressure during the collecting phase, and also in the contraction pressure and voided volume of the emptying phase. The present study suggests that the cerebellum plays an inhibitory role in the collecting phase and a facilitatory role in the emptying phase during the entire reflex micturition cycle of the decerebrate dog. Further study will have to be done concerning the neurotransmission mechanism that causes these different effects in the collecting and emptying phases.

Animals↗
PubMed1989

Application of Doppler color flow imaging method on the detection of vesicoureteral reflux.

The doppler color flow imaging method was employed to detect the vesicoureteral reflux. The ultrasound examination was performed by using the doppler color flow imaging system. Ultrasonic sector scan was carried out by the use of the 3.75 MHz phased array and/or conbex array transducer with a transabdominal approach. The flow in the bladder from the ureteral orifice to the bladder was detected with a red color indicating the direction towards the probe and the flow from the bladder towards the ureteral orifice during the vesicoureteral reflux was detected with a blue color indicating the direction away from the probe. The doppler color flow imaging method appears to be a useful diagnostic procedure for the detection of the vesicoureteral reflux.

Child, Preschool↗
PubMed1988

Intracellular processing of measles virus fusion protein.

Intracellular processing of measles virus fusion (F) protein was studied by radiolabeling and immunoprecipitation with a monoclonal antibody against F protein. The cleavage of F protein into F1 and F2 subunits was complete after 5 hours of chase during which the growth of oligosaccharide chains on the F2 domain of F protein continued. The addition of terminal sialic acid conferred a strong negative charge on the F2 subunit. F protein expressed on the cell surface was removed by a fungal semi-alkaline protease, providing a method to follow the kinetics of its transport to the cell surface. The transport of the F protein was faster than that of the hemagglutinin (HA) protein. Uncleaved F protein, as well as cleaved subunits became digestible by the protease, indicating that a portion of the F protein reaches the cell surface uncleaved. The treatment of measles virus-infected cells with tunicamycin resulted in the synthesis of unglycosylated HA (65 kilodaltons, Kd) and F (48 Kd) proteins. Unglycosylated F protein was not cleaved into smaller subunits, nor was it transported to the cell surface. Unglycosylated HA protein likewise failed to reach the cell surface.

Antibodies, Monoclonal↗
PubMed1988

A burst-promoting activity derived from the human bone marrow stromal cell line KM-102 is identical to the granulocyte-macrophage colony-stimulating factor.

Recently, several human bone marrow stromal cell lines have established and produced hematopoietic growth factors. One of these factors, a burst-promoting activity (BPA), was purified from 6 liters of serum-free conditioned medium cultured from stromal cell line KM-102, which was stimulated by phorbol myristate acetate (PMA) and calcium ionophore A23187. This stimulation induced 60 times more production of BPA than the unstimulated control culture. BPA was purified 4000-fold by sequential fractionation using ammonium sulfate precipitation, anion-exchange and lentil lectin affinity chromatographies, high performance gel filtration chromatography, and reversed phase high performance liquid chromatography. Purified BPA gave a single broad band of protein with a molecular weight of approximately 18 kd, as assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The concentration required for half maximal growth of early erythroid colonies was estimated as 10 pg/ml or 0.6 pM. At a higher concentration (125 pg/ml) this factor also stimulates the growth of granulocyte, macrophage, and eosinophil colonies in agar culture. The profile of amino acid composition is very similar to that of the human granulocyte-macrophage colony-stimulating factor (GM-CSF) deduced from its complementary DNA sequence. The result of amino-terminal sequence analysis strongly suggests that the purified material consists of GM-CSF and tetrapeptide-deleted GM-CSF. Moreover, antibody against GM-CSF completely neutralized the biological activities of this factor. These results indicate that the human bone marrow stromal cell line secretes GM-CSF as a burst-promoting activity and GM-CSF may play a significant role in the interaction between stem cells and stromal cells in the hematopoietic microenvironment.

Amino Acid Sequence↗
PubMed1988

[Effect of oxybutynin on lower urinary tract function].

The effect of oxybutynin on lower urinary tract function was studied by combined recording of cystometry and sphincter electromyogram (EMG) in 7 decerebrate dogs. Micturition was induced by bladder filling before and after oxybutynin. The statistical analysis was carried out on the urodynamic parameters. Oxybutynin at a dose of 30, 100, and 300 micrograms/kg significantly increased the threshold volume during the collecting phase in a dose dependent manner. In the urodynamic parameters of the emptying phase considered to be influenced by cholinergic activity there was a small but significant decrease in maximum pressure only at 300 micrograms/kg. Therefore, oxybutynin is probably acting as a strong antispasmodic agent. Oxybutynin seems to be useful for the relief of symptoms associated with detrusor instability and hyperreflexia.

Animals↗
PubMed1987

Protective effect of antibodies to two viral envelope glycoproteins on lethal infection with Newcastle disease virus.

The protective effect of humoral immunity against lethal infection of chickens with Newcastle disease virus was studied. Chickens hatched from eggs laid by hens vaccinated with live attenuated Newcastle disease virus vaccine possessed antibody to various components of the virus, and were resistant to a challenge with a virulent strain of Newcastle disease virus which was 100 per cent fatal for the offspring of nonvaccinated hens. Passive administration of antiserum raised against whole virions provided susceptible chickens protection comparable to that seen in the birds with maternal antibody. When administered passively, both anti-HN serum with virus neutralizing activity, and anti-F serum with only marginal virus neutralizing activity significantly prolonged the survival of infected birds but failed to achieve the level of protection as afforded by the anti-whole NDV serum. The protection provided by the simultaneous presence of anti-HN and anti-F serum was significantly greater than that afforded by either alone and comparable to that of anti-whole NDV serum, indicating the complementary effect of anti-HN and anti-F antibodies not only in cell cultures as reported previously (19), but also in a natural host.

Animals↗
PubMed1987

Role of the pelvic nerve in the dynamics of micturition in the decerebrate dog as determined by suprapubic endoscopical and urodynamic evaluation.

The role of the pelvic nerves on the dynamics of micturition was evaluated in 13 decerebrate dogs, four male and nine female, by direct observation of bladder movement, by suprapubic cystoscopic observation of urethral behavior, and by pressure flow EMG studies. Experiments were performed before and after unilateral pelvic nerve transection. In control conditions and after unilateral pelvic nerve transection, the bladder neck was not tightly closed during the collecting phase, the membranous portion of the urethra opened and closed spasmodically during the emptying phase, and reflex micturition developed. Direct observation showed that after unilateral pelvic nerve transection, the ipsilateral bladder did not contract. A pressure flow EMG study showed that unilateral pelvic nerve transection produced a significant increase in threshold volume, threshold pressure, bladder compliance and residual volume, and a significant decrease in contraction pressure and flow rate. The present study shows that unilateral pelvic nerve transection has no demonstrable effect on urethral function, but has effects on bladder function during the collecting and emptying phases and that bladder innervation is unilateral in the dog.

Animals↗
PubMed1987

Effect of N-ethylmaleimide on Ca-inhibition of Physarum myosin.

We have established a quick method for preparing Physarum myosins whose actin-activated ATPase activities are inhibited by microM levels of Ca2+ (from plasmodial stage: Kohama, K. & Kendrick-Jones, J. (1986) J. Biochem. 99, 1433-1446; and from amoebal stage: Kohama, K., Takano-Ohmuro, H., Tanaka, T., Yamaguchi, Y., & Kohama, T. (1986) J. Biol. Chem. 261, 8022-8027). N-Ethylmaleimide alkylates sulfhydryl (SH) groups on the heavy chains in the heads of the plasmodial myosin. The actin-activated ATPase activity of the modified myosin was significantly decreased when assayed in low Ca2+ concentrations. Moreover, the activity remained low even when the Ca2+ concentrations was increased, i.e., the myosin was desensitized. For complete desensitization, about 4 mol SH per mol myosin (500,000 Mr) must be modified. These residues are probably the "reactive thiols" which have been predicted from primary structure studies to be conserved among myosins of higher and lower eukaryotes. Ultraviolet absorption spectra of the modified and intact myosins showed a peak at 277 nm. The height of this peak in intact myosin was reduced when the Ca2+ concentration was increased. This Ca-induced reduction was hardly detectable in the modified myosin although Ca-binding activity to myosin did not appear to be affected by the modification. We interprete these results that Ca2+ may change the conformation of the myosin heavy chain by binding to myosin and speculate that impairment of this process upon modification could cause the desensitization to Ca2+ in the ATPase activity.

Actins↗
PubMed1987

[Effects of terodiline on lower urinary tract function].

The effects of terodiline on lower urinary tract function were studied using decerebrated dogs. The micturition cycles were investigated by pressure flow EMG study before and after the administration of terodiline. The statistical analysis was carried out on the urodynamic parameter. Terodiline at a dose of 1 mg/kg decreased the opening pressure, contraction pressure, and flow rate and increased the residual volume. A decrease in threshold pressure, average flow rate and an increase in bladder compliance also occurred after the administration of terodiline at the dose of 3 mg/kg. Terodiline appears to decrease bladder activity and is useful for pollakisuria.

Animals↗
PubMed1986

Isolation and characterization of myosin from amoebae of Physarum polycephalum.

Myosin was isolated from amoebae of Physarum polycephalum and compared with myosin from plasmodia, another motile stage in the Physarum life cycle. Amoebal myosin contained heavy chains (Mr approximately 220,000), phosphorylatable light chains (Mr 18,000), and Ca2+-binding light chains (Mr 14,000) and possessed a two-headed long-tailed shape in electron micrographs after rotary shadow casting. In the presence of high salt concentrations, myosin ATPase activity increased in the following order: Mg-ATPase activity less than K-EDTA-ATPase activity less than Ca-ATPase activity. In the presence of low salt concentrations, Mg-ATPase activity was activated approximately 9-fold by skeletal muscle actin. This actin-activated ATPase activity was inhibited by micromolar levels of Ca2+. Amoebal myosin was indistinguishable from plasmodial myosin in ATPase activities and molecular shape. However, the heavy chain and phosphorylatable light chains of amoebal myosin could be distinguished from those of plasmodial myosin in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, peptide mapping, and immunological studies, suggesting that these are different gene products. Ca2+-binding light chains of amoebal and plasmodial myosins were found to be identical using similar criteria, supporting our hypothesis that the Ca2+-binding light chain plays a key role in the inhibition of actin-activated ATPase activity in Physarum myosins by micromolar levels of Ca2+.

Adenosine Triphosphatases↗
PubMed1986

Effect of carboxylic ionophores on measles virus hemagglutinin protein.

We have studied the effect of two carboxylic ionophores, monensin and laidlomycin, on the replication of measles virus in KB cells. The yield of infectious virus was markedly depressed at the concentrations of the ionophores which had no effect on overall viral protein synthesis. The ionophores selectively blocked the migration of hemagglutinin (H) glycoprotein from Golgi apparatus to the cell surface. As a result, H glycoprotein is prevented from being converted from incompletely glycosylated form to the mature form. The inhibitory effect on the transport and glycosylation of H was reversed, although gradually, upon the removal of the ionophores.

Anti-Bacterial Agents↗
PubMed1985

Maturation of measles virus hemagglutinin glycoprotein.

The processing of measles virus hemagglutinin glycoprotein (H) in infected cells was studied by pulse-chase method and two-dimensional isoelectric focusing and SDS-polyacrylamide slab gel electrophoresis. H glycoprotein was synthesized initially as polypeptides smaller than H glycoprotein present in the virions. They were then processed into a cohort of polypeptides of larger molecular size and with reduced charge. The change was associated with the expression of H glycoprotein on the cell surface. The removal of sialic acid from carbohydrate chain of H glycoprotein resulted in the shift of isoelectric point to a more basic range. The entire process of maturation of H glycoprotein required approximately 5 hours. Carbohydrate content in H was determined to be approximately 12 per cent by weight. Mannose, galactose, fucose, N-acetylglucosamine, and N-acetylneuraminic acid were the constituent monosaccharides.

Carbohydrate Metabolism↗