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Biomedical subjects

T Ohkawa

Publications and source records attributed to T Ohkawa.

At least 253 records · Page 14Linked to original sources
PubMed1979

Alterations of the thymus and peripheral lymphoid tissues in fatal measles. A review of 14 autopsy cases.

As a result of re-examining 14 autopsy cases of fatal measles, neither aplastic nor hypoplastic thymuses were found even in a case with giant cell pneumonia, but there were degenerative and/or necrotic changes with giant cells mostly in the thymus and less in the peripheral lymphoid organs such as spleen, lymph nodes, Peyer's patches and tonsils. This damage of the lymphoid system was associated with the occurrence of complications, particularly of giant cell pneumonia and encephalitis. The lymphoid cell damage, which might be primarily due to virulence of the infected measles virus, seemed to prolong the viremia. Involvement of viremia in the process of complication is discussed.

Brain↗
PubMed1979

[Pharmacological properties of procaterol, a newly synthesized, specific beta 2-adrenoceptor stimulant. Part II. Effects on the peripheral organs (author's transl)].

Pharmacological properties of procaterol (PRO) in the peripheral organs were examined in comparison with those of sulbutamol (SAL) and isoproterenol (ISO). PRO slightly enhanced twitch tension of the tibialis anterior muscle but affected little the mono- and poly-synaptic spinal reflexes and ganglionic transmission. PRO depressed spontaneous contractions of the isolated ileum, non-pregnant and pregnant uterus and also the gastrointestinal and uterine movements in vivo. PRO prolonged the time of peroral charcoal transport in the intestine. Potencies of PRO in producing these effects were between those of ISO and SAL except those on the uterus in which PRO was more potent than ISO and SAL. Pro depressed gastric and bile secretion but had no effect on pancreatic secretion. ISO, PRO and SAL reduced resistance of the common carotid, femoral and renal arteries and the relative potencies of PRO and SAL to ISO were significantly less in the renal artery than in the other arteries. In accelerating heart rate in conscious rats and dogs, PRO (p.o. or s.c.) was almost equipotent to SAL. Urine flow, GFR, RPF, free water and osmolar clearance and also excretion of electrolytes were reduced by PRO with the concomitant fall of systemic blood pressure. PRO has no effect on blood coagulation and hemolysis but inhibited carrageenin edema and an increase in permeability of blood vessels induced by acetic acid. PRO had no alpha-adrenolytic, cholinolytic and anti-histaminic effects.

Adrenergic beta-Agonists↗
PubMed1978

A radioimmunoassay of serum 16alpha-hydroxypregnenolone with specific antiserum.

A radioimmunoassay for plasma 16alpha-hydroxypregnenolone has been developed using anti-16alpha-hydroxypregnenolone antiserum produced in rabbits immunized with 16 alpha-hydroxypregnenolone-3-succinate-bovine serum albumin. Radioimmunoassay data were processed and analysed for its validity using a four parameter logistic curve fitting routine with use of the IBM call system. The assay system was satisfactory for a routine use. The 16alpha-hydroxypregnenolone concentrations in the umbilical cord blood at term ranged from 223 to 324 ng/ml. Gas liquid chromatographic analysis revealed a similar result, and also the presence of this steroid in the adrenal gland of the human fetus at midtrimester was confirmed. It is speculated that this steroid is secreted from fetal adrenals.

17-alpha-Hydroxypregnenolone↗
PubMed1976

Studies of intracellular thymidine nucleotides. Relationship between the synthesis of deoxyribonucleic acid and the thymidine triphosphate pool in Escherichia coli K12.

The two types of mutant strains which show resistance to T-even phage infection have been isolated and been shown to have either a higher or lower ratio of dTDP-sugar to dTTP than that of the parent strains. The one with a higher ratio of dTDP-sugar to dTTP than the parents has a large dTDP-sugar pool and small dTTP pool, and a high level of dTDPG pyrophosphorylase activity. The other one, with a lower ratio of dTDP-sugar to dTTP than the parents, has a small dTDP-sugar pool and large dTTP pool, and a low or deficient level of this enzyme activity. They form an entirely mucoid colony in the synthetic agar plate. Mutant cells (Ter-6 and Ter-21) which have deficient dTDPG pyrophosphorylase activity show 2 -- 3 times higher activity of UDPG pyrophosphoyrlase than that of parent cells. The dTDPG pyrophosphorylase-deficient mutants (Ter-15 and Ter-21) have a 3 -- 4 times higher concentration of dTTP and a faster rate of DNA synthesis and cell division than those of parent strains in growth with external thymine. The dTDPG pyrophosphorylase constitutive mutant (Ter-4) has a 0.5 -- 0.33 smaller dTTP pool and a slower rate of DNA synthesis and cell division than those of parent cells grown in the same medium. In the Ter-15 and Ter-21 mutants, the intracellular dTTP-dependent DNA synthesis rapidly disappeared in thymine suboptimal concentration, but the Ter-4 mutant maintained its dTTP-dependent DNA synthesis over a 20 muM concentration of external thymine. In high concentration (100 muM) of external thymidine, the thymidine effects on the intracellular dTTP concentration do not significantly appear in these enzyme-deficient mutants (Ter-15 and Ter-21). Also, the concentration of intracellular dTTP in the cell growth with external thymidine is 2.5 times greater than that with external thymine in these enzyme-deficient mutants (Ter-15 and Ter-21).

Cell Division↗
PubMed1975

Studies of intracellular thymidine nucleotides. Thymineless death and the recovery after re-addition of thymine in Escherichia coli K 12.

In a thymine-deprived culture, the mutant cells (deficient in dTDP-glucose pyrophosphorylase activity and named Ter-15) lose viability at a faster rate, form longer filaments for the first 60 min and lose thymidine nucleotides and dTDP-sugar pools at a faster rate for the first 15 min than those of the parent cells, but the dTDP-sugar pool in the parent cells is maintained at high concentration for the first 90 min during thymine starvation. In the recovery of cell growth after re-addition of thymine into the thymine-deprived culture, parent cells recommence growth immediately, but the mutant cells (Ter-15) show a lag-phase for 45 min after which time their growth recommences. The rate of dTTP synthesis for the first 10 to 15 min after re-addition of thymine to thymine-deprived cultures of parent and mutant (Ter-15) cells is three-fold higher than that of thymine nondeprived culture (control), but the rates of dTMP and dTDP-sugar syntheses are the same as those of the control. The total DNA synthesis after re-addition of thymine is equal to that of the control, and the period of thymine starvation other than the number of viable cells during thymine starvation plays an important role. After separation of the filament cells from normal-sized cells by sucrose gradient centrifugation, the initial rate of DNA synthesis of filament cells is three-fold faster than that of normal-sized cells. These results show that the dependency of DNA synthesis upon dTTP concentration is maintained after re-addition of thymine into thymine-deprived culture.

Cell Survival↗