Seroepidemiology of human T-cell leukemia virus type-I in the Republic of Korea

We investigated the prevalence of antibodies to human T-cell leukemia virus type I (HTLV-I) associated antigens in various patients and healthy individuals in the Republic of Korea. Seventeen out of 6,255 individuals (0.27%) were seropositive. The positive rate in males was 0.21% and that in females was 0.36%, the sex difference being similar to that in endemic areas in Japan. HTLV-I carriers were found in Seoul and neighboring areas, but not in Busan city or Jeju Island, which are adjacent to Kyushu, Japan. The prevalence of sera with definite anti HTLV-I antibodies seems to be very low in the Republic of Korea.

A signal sequence mutant defective in export of ribose-binding protein and a corresponding pseudorevertant isolated without imposed selection

Ribose-binding protein is exported to the periplasmic compartment of Escherichia coli by a process that involves proteolytic cleavage of an amino-terminal extension of amino acids from the precursor form of the protein. In a collection of mutants isolated as defective in the Rbs transport system, a strain was identified that contained only precursor ribose-binding protein, none of which was exported to its normal location in the periplasm. The mutated rbsB contained a base substitution that results in a change of leucine to a proline at position-17 in the signal sequence. A pseudorevertant of the mutant contained proteolytically processed, active ribose-binding protein in the periplasm. The pseudorevertant rbsB carried a second mutation: serine at position-15 in the signal sequence was changed to phenylalanine. Isolation of a signal sequence mutant and a corresponding pseudorevertant without specific selection or site-directed mutagenesis emphasizes the possibility of obtaining export mutants without the use of procedures that could bias or limit the range of mutations found. Explanation of the extreme phenotype of the mutant and the effective correction of that phenotype in the pseudorevertant requires extension of current notions of critical features of signal sequences.

Detection and quantitation of low levels of protected and unprotected (R)-amino acids in the synthesis of thymopentin, an immunoregulatory peptide

Two chiral chromatographic procedures (HPLC and capillary GC) were developed to monitor the extent of epimerization of protected and unprotected amino acids used in a synthesis of thymopentin, an immunoregulatory peptide currently in clinical trials. The capillary GC method allowed the detection of the (R)-enantiomer in the presence of the (S)-enantiomer at levels of greater than or equal to 0.2%, while the HPLC method allowed similar detection at levels of greater than or equal to 0.1%.

Safety of cefotaxime and other new beta-lactam antibiotics

beta-Lactam antimicrobial agents have until recently enjoyed a reputation of reliability and safety. Now serious problems have emerged associated with use of some of the newer drugs of this class. Latamoxef (moxalactam) and cefoperazone, both of which have a methyltetrazolethiol side chain, have been reported to cause coagulation abnormalities, clinical bleeding, and disulfiram-like reactions. In addition, an unusually high incidence of diarrhoea has been associated with administration of cefoperazone. Cefotaxime does not have the [methylthiotetrazole] side chain and has not caused bleeding, coagulopathy, or disulfiram-like reactions. Diarrhoea, usually mild, has been observed in only 1% of patients given cefotaxime in clinical trials. The remarkable safety record of cefotaxime is an important consideration for clinicians in the selection of an antimicrobial agent for seriously ill patients.

Regulation of thyroid ornithine decarboxylase by the polyamines. Induction of a protein inhibitor of ornithine decarboxylase by the end-products of the reaction

When spermidine, putrescine or 1,3-diaminopropane was injected (12.5 mumol/100 g body weight) into rats 1 h before thyrotropin, ornithine decarboxylase activity was increased by 75--150% over control levels. However, when greater than or equal to 75 mumol polyamine/100 g body weight was injected, thyrotropin-activated activity was inhibited by 70--95%. Multiple polyamine injections inhibited goitrogen-induced activity and gland weight increase by approx 35%. The polyamines also inhibited thyrotropin-activated rat thyroid ornithine decarboxylase in vitro in a dose-related fashion, with 50% inhibition occurring at 2--5 . 10(-4)M. The inhibition was not due to a direct effect on the enzyme. No stimulation was seen with low concentrations of polyamine. The polyamines had no effect on in vitro thyroid protein/RNA synthesis or glucose oxidation but had a biphasic effect on plasma membrane adenylate cyclase activity. A protein inhibitor to thyroid ornithine decarboxylase was generated in vivo by multiple injections of the polyamines into rats and in vitro by incubating bovine thyroid slices with 2--10 mM polyamine. The inhibitor was non-dialyzable, destroyed by boiling, and its formation was blocked in a dose-related fashion by cycloheximide. We conclude that: (1) thyroid ornithine decarboxylase is subject not only to positive control, but is also negatively regulated by its end-products, the polyamines, which induce a protein inhibitor to ornithine decarboxylase; (2) since gland growth is also inhibited under these conditions, the polyamine effect on thyroid ornithine decarboxylase may be biologically significant.

Fatal pulmonary involvement in dermatomyositis

A 12-year-old boy with classic dermatomyositis developed a rapidly progressive pulmonary process that led to his death a month later. Physiologically, there was interference with the oxygenation of the blood even when 100% oxygen was delivered to the lungs under pressure. Microscopic examination of the lungs disclosed diffuse interstitial pulmonary fibrosis. We conclude that these pulmonary changes were a component of the basic disease.

Regulation of thyroid ornithine ornithine decarboxylase (ODC) by thyrotropin. I. The rat

We studied the effects of TSH on rat thyroid ornithine decarboxylase (ODC) activity. After 1 day of goitrogen treatment, there was an abrupt fall in serum triiodothyronine (T3) a rise in circulating TSH, and a dramatic increase in thyroid ODC activity. Despite the continued rise in TSH and progressive increase in thyroid gland size with further treatment, thyroid ODC activity declined on the third day and remained at submaximal levels. Thyroid ODC activity was also stimulated in a dose-related manner by administration of exogenous TSH. Little TSH effect was noted before 3 h. Maximal ODC activity occurred between 4 and 5 h. The TSH stimulation of ODC could be inhibited by pretreatment with actinomycin D or cycloheximide, suggesting that the increase in ODC activity requires new RNA and protein synthesis. Although pretreatment with agents that alter microtubule structure (e.g., colchicine and vinblastine) prevent stimulation of ODC activity by TSH, additional data suggest, but do not confirm, that hrmone secretion and ODC activation may be dissociable. Further studies were undertaken to determine whether cyclic AMP (cAMP) or prostaglandins played any role in the regulation of thyroidal ODC activity. Dibutyryl cAMP, alone, or together with aminophylline, did not stimulate thyroidal ODC activity in dosages which concomitantly stimulated adrenal enzyme activity. Likewise, prostaglandin E2 (PGE2) did not stimulate thyroidal ODC activity, but did stimulate adrenal enzyme activity in a dose-related manner. However, pre-treatment of rats with inhibitors of prostaglandin synthesis prevented the activation of thyroidal ODC BY TSH. One inhibitor, indomethacin, attenuated the TSH stimulation of enzyme activity in a dose-related manner. Indomethacin pretreatment also resulted in approximately a 10-fold decrease in thyroidal prostaglandin levels. Exogenous PGE9, in dosages as high as 500 pg, did not overcome the inhibitory effect of indomethacin on ODC activation. Although the precise role for endogenous prostaglandins remains to be defined, it does appear that a reduction in thyroidal prostaglandins prevents activation of the enzyme by TSH.