Studies on the origin of the near-infrared (800–900 nm) absorption of cytochrome c oxidase

Data are presented which were collected in the course of the past ten years and bear on the correlation of absorbance at 800 nm and the EPR signal at g = 2 (‘copper signal’) of cytochrome c oxidase in various states of oxidation and ligation. Both EPR and optical reflectance spectra were obtained at low temperature (?170 to ?190°C). For some sets of samples spectra were recorded in the range 500–1100 nm. A particular effort was made to study this correlation with what are called ‘mixed valence’ states (Greenwood, C., Wilson, M.T. and Brunori, M. (1974) Biochem. J. 137, 205–215), when cytochrome a and the EPR-detectable copper are thought to be oxidized and the other components reduced and vice versa. These data show no evidence that the copper component of cytochrome oxidase which has so far not been detected by EPR makes a contribution to the absorption between 800 and 900 nm exceeding 10–15% of the total, which is close to or within the error of the respective measurements. For the various states of the oxidase examined in this work the 700–800 nm region did not appear to be more useful than the 800–900 nm region for determining the state of the EPR-undetectable copper in a reliable way. These conclusions are in agreement with results presented previously from other laboratories concerning the relationship of optical (approx. 800 nm) and EPR spectroscopic (g = 2) data obtained with the enzyme.     

T-lymphocyte function and sensitivity to interferon in trisomy 21

Previous studies have shown that cells from subjects with trisomy 21 have enhanced sensitivity to the antiviral effects of interferon, presumably because of the location of the gene, IfRec, coding for the species-specific response to interferon on chromosome 21. Interferon is also known to have many other effects including the ability to inhibit the proliferation of many types of cells. To determine whether proliferating trisomic lymphocytes are more sensitive to the antiproliferative effect of interferon we have investigated, using healthy noninstitutionalized subjects with trisomy 21, the ability of interferon to inhibit the proliferation of lymphocytes stimulated with phytohemagglutinin P(PHA), concanavalin A (Con A), and tetanus toxoid. The trisomic subjects had normal numbers of peripheral blood leukocytes, and normal numbers and proportions of T and B lymphocytes. The production of interferon by PHA-stimulated trisomic T lymphocytes was normal. Trisomic lymphocytes also had normal proliferative responses to PHA and Con A. There were no differences between the inhibitory effects of interferon on the proliferation of PHA-stimulated trisomic and normal lymphocytes. However, trisomic lymphocytes stimulated with low doses of Con A did display significantly enhanced sensitivity to the antiproliferative effects of interferon. In contrast to normal lymphocytes, trisomic lymphocytes were not stimulated to proliferate by tetanus toxoid, and exposure to interferon resulted in enhancement, rather than inhibition, of DNA synthesis.     

Diazepam induces relaxation of chick embryo muscle fibers in vitro and inhibits myosin synthesis

Diazepam (Valium/Roche) causes an immediate cessation of spontaneous contraction in chick embryo skeletal muscle fibers growing in vitro. Between 24–48 h later in the presence of 100 μM diazepam the relaxed muscle fibers no longer accumulate myosin as measured by the total amount of myosin heavy-chain peptide extracted from the cell cultures and identified by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The myosin heavy chain assay procedure was standardized by quantitative precipitation of myosin with antibody to column purified chicken skeletal muscle myosin. Failure to accumulate myosin is related to a progressive inhibition of myosin synthesis. Diazepam-treated cultures showed an 80% inhibition of myosin heavy-chain synthesis over a period of 4 days. At the same time the rate of myosin heavy-chain degradation increases in diazepam-treated cultures relative to matched control cultures. Total protein synthesis was only marginally affected suggesting that diazepam may differentially inhibit myofibrillar protein synthesis. All of the observed effects of diazepam were reversible if drug exposure was limited to 48 h. The apparent specificity and reversibility of diazepam suggests that the drug will be useful in probing the mechanisms of terminal skeletal muscle cell differentiation and the hypotrophic relationship between chronic relaxation and inhibition of accumulation of myosin and perhaps other myofibrillar proteins.     

Role of vitamin E in the etiology of spontaneous hemorrhagic necrosis of the central nervous system of fetal hamsters

The intraperitoneal inoculation of pregnant hamsters with vitamin E during the first half of gestation reduced the severity or eliminated the occurrence of grossly observable effects of spontaneous hemorrhagic necrosis (SHN) of the central nervous system in their offspring and improved the pre-weaning viability of their litters. The addition of corn oil (16%) or linoleic acid (8%) to a ration associated with the occurrence of SHN in fetal hamsters enhanced the incidence and severity of the disease, and these effects were moderated by inoculation of the dams with vitamin E. Experimental data indicated that, among multifactorial contributions to the cause of SHN in hamsters, vitamin E availability and levels of dietary polyunsaturated fatty acid played a significant and interrelated role.