Mitochondrial thyroid hormone receptor: localization and physiological significance.

Binding studies of thyroid hormone to submitochondrial fractions from rat liver suggest that the component responsible for high-affinity, low-capacity (saturable) binding of hormones arises from the inner mitochondrial membrane. The partially purified component, approximately 150,000 daltons, appears to be half protein and half lipid, largely phospholipids, tentatively identified as lecithin, phosphatidyl ethanolamine, and cardiolipin. A similar hormone-binding macromolecule was found in mitochondria from rabbit kidney, from human liver and kidney, and from rat kidney, myocardium, skeletal muscle, intestinal mucosa, whole small intestine, adipose tissue, and lung. It was absent from mitochondria of adult rat brain, spleen, and testis, organs calorigenically unresponsive to thyroid hormones injected in vivo, but was present in mitochondria from brains of rats 12 days old and younger. The organ distribution of the hormone-binding protein and its presence in neonatal brain mitochondria supports the biological relevance of the mitochondrial component as a thyroid hormone receptor.

Thyroid hormone action: the mitochondrial pathway.

The subcellular compartments have been investigated to compare proteins capable of binding triiodothyronine and thyroxine; specific binders have been found in cytosol, nuclei, and mitochondria from rat liver and kidney. The binding protein from the inner mitochondrial membrane had the highest association constant (greater than 10(11) liters per mole), suggesting possible direct hormone action on the mitochondria. Binding of hormone analogs was found to be related to known physiological potency, and stereospecific discrimination between L- and D-thyroxine was observed. The saturable receptor was found in the mitochondrial membranes of rat liver, kidney, myocardium, and skeletal muscle but not in mitochondria from the unresponsive tissues: brain, spleen, and testis. Oxidative phosphorylation by mitochondrial vesicles from hypothyroid rats increased after the addition of physiological concentrations of triiodothyronine, which corroborated direct hormone action on mitochondria.

Clinical evaluation of a new herpes simplex virus ELISA: a rapid diagnostic test for herpes simplex virus.

A new sensitive and rapid enzyme-linked immunosorbent assay (ELISA) test (Du Pont HERPCHEK) for the detection of herpes simplex virus (HSV) antigen was evaluated. A total of 563 clinical samples collected from patients attending obstetrics and gynecology and sexually transmitted disease clinics in two geographic locations were tested by ELISA, and the results were compared with virus isolation in cell culture. The sensitivity and specificity of the ELISA were 97.5 and 98.6%, respectively. When a confirmatory blocking ELISA was used to demonstrate the presence of HSV antigen in culture-negative but ELISA-positive samples, the specificity of the assay increased to 100%. The assay is easy to perform and may be used to diagnose HSV infection rapidly without the need for culture confirmation.

Effect of low-dose oral contraceptives on natural killer cell activity.

Several reports indicate an association between oral contraceptives and increased infection rates. One mechanism that could explain this increased infection rate is a decrease in immune function. A study comparing T cell subsets showed no differences in numbers between oral contraceptive users and controls. In this study, natural killer cell activity was compared in women before and 3 and 6 months after oral contraceptive use. There was a statistically significant decrease in NK cell activity after three months. There was no further decrease by six months and the differences were no longer significant due to greater variability. No infections were reported during the study period. Thus, the observed reduction in NK activity was either physiologically insignificant or the previously reported increase in infections may be the result of non-immunological factors.

PIP: Over the last 10 years there have been occasional reports of higher incidence of candidiasis, herpes virus infection, Chlamydia trachomatis infection, Gardnerella vaginalis infection, and bacteriuria in women using oral contraceptives. In this study natural killer cell activity was compared in 20 women, aged 18-24, before and 3 and 6 months after they were given a 3-month supply of oral contraceptives containing norethindrone (.5-1 mg)/ethinyl estradiol (.035 mg). Natural killer cells are lymphoid-like cytotoxic effector cells, that lyse tumor and virally infected cells. Their activity was measured by labelling K562 target cells with 51Cr. After 3 months of oral contraceptive use, natural killer cell activity decreased by 12-16%, but there was no further reduction after 6 months; and there were no viral, bacterial or fungal infections in the study group.

Multicenter clinical evaluation of the Du Pont Herpchek HSV ELISA, a new rapid diagnostic test for the direct detection of herpes simplex virus.

A new 4h rapid enzyme-immunoassay for direct detection of herpes simplex virus (HSV) antigen (Du Pont Herpchek) was evaluated with 743 clinical samples collected at obstetrics and gynecology (OB/GYN), sexually transmitted diseases (STD), and ophthalmology clinics. The sensitivity and specificity of Herpchek was 98.0% and 98.4% respectively compared to virus isolation in cell culture. Confirmatory blocking ELISA tests, clinical history and follow up indicate that the true specificity of the test is 100%.

Acyclovir for genital herpes simplex virus infections. A review.

Genital herpes simplex virus (HSV) causes a common and debilitating infection seen by the gynecologist and obstetrician. Over the last decade this disease has become nearly an epidemic in the United States. A recent, major advance in antiviral chemotherapy, acyclovir, allows safe, effective treatment and suppression of HSV infection.

Thyroid hormone binding by a component of mitochondrial membrane.

The thyroid hormone, triiodothyronine, has been shown to be bound by the intranuclear chromatin protein associated with active DNA, where it is believed to stimulate transcription. Evidence exists that the thyroid hormones have direct action not only on nuclei, but also on mitochondria. Threfore, specific proteins that bind thyroid hormones in the mitochondria should be demonstrable. Mitochondria were isolated from homogenized rat livers by sedimentation through 0.25 M sucrose solution, followed by washing four times to free them of microsomes. Strong binding of thyroid hormones was observed in mitochondrial fractions prepared from both the membranes and the matrix. After incubation in an ice bath with increasing amonts of triiodothyronine with added tracer [125I]triiodothyronine, the matrix infrequently contained specific saturable receptor sites, but usually exhibited strong "nonspecific" interaction...

Suppression of newborn natural killer cell activity by prostaglandin E2.

The effect of prostaglandin E2 on natural killer cell activity of cord blood was examined. Natural killer cell activity, determined by chromium 51 release, was significantly reduced after prostaglandin E2 (1 microgram/ml) treatment. Prostaglandin E2 has been found to enhance the cellular spread of herpesvirus. Thus prostaglandins may enhance viral infections indirectly by suppressing natural killer cell activity.

Enhancement of maternal and neonatal natural killer cell activity with interleukin-2.

Natural killer cell activity, which is vital to the immune surveillance against viruses and tumor cells, is significantly lower in the newborn infant than in the mother. Incubation of maternal and cord blood lymphocytes with interleukin-2 significantly increases natural killer activity in both. The increase is substantially greater in the cord blood lymphocytes.

Partial purification of thyroid hormone receptor from mitochondrial inner membrane: evidence for a physiologic role.

Recently we described a protein component, from the inner mitochondrial membrane, which binds thyroid hormone with high affinity, low capacity (saturable) characteristics. This partially purified rat liver mitochondrial membrane component appears to be a 150,000 daltons lipoprotein complex. Phospholipids, tentatively identified as lecithin, phosphatidyl ethanoamine, and cardiolipin, appear to constitute 50% of this complex. A similar hormone binding marcomolecule was also found in mitochondria from rabbit kidney, as well as human liver and kidney. In the rat this saturable thyroid hormone binding component was found in mitochondria from liver, kidney, myocardium, skeletal muscle, intestinal mucosa, whole small intestine, adipose tissue, and lung. It was absent from the mitochondria of adult brain, spleen and testis, organs known to be calorigenically unresponsive to thyroid hormones injected in vivo. In contrast, neonatal rat brains contain the protein with binding constants similar to those of neonatal or adult rat liver mitochondria, but in older rat brains (14 and 17 days) the saturable binding was no longer present, as in adult brain. These data provide strong support for the biological relevance of the mitochondrial component as a thyroid hormone receptor.

Failure of ibuprofen in treatment of herpes genitalis.

Motrin (ibuprofen), a potent inhibitor of prostaglandin synthetase, was tested in women and men for treatment of recurrences of genital herpes. In a double-blind trial, no statistically significant differences were observed between treated and placebo groups in any of the measured parameters.

The plasma transport and metabolism of retinoic acid in the rat.

The transport of retinoic acid in plasma was examined in vitamin A-deficient rats maintained on small doses of radioactively labelled retinoic acid. After ultracentrifugation of serum adjusted to density 1.21, most of the radioactivity (83%) was associated with the proteins of density greater than 1.21, and not with the serum lipoproteins. Gel filtration of the labelled serum on Sephadex G-200 showed that the radioactive label was associated with protein in the molecular-weight range of serum albumin. On polyacrylamide-gel electrophoresis almost all of the recovered radioactivity migrated with serum albumin. Similar esults were obtained with serum from a normal control rat given a single oral dose of [(14)C]retinoic acid. These findings indicate that retinoic acid is transported in rat serum bound to serum albumin, and not by retinol-binding protein (the specific transport protein for plasma retinol). Several tissues and the entire remaining carcase of each rat were extracted with ethanol-acetone to determine the tissue distribution of retinoic acid and some of its metabolites. The total recover of radioactive compounds in in the entire body of the rat was about 7-9mug, representing less than 5% or 10% respectively of the total administered label in the two dosage groups studied. The results confirm that retinoic acid is not stored in any tissue. Most of the radioactive material was found in the carcase, rather than in the specific tissues analysed. Two-thirds of the radioactivity in the carcase appeared to represent unchanged retinoic acid. Of the tissues examined, the liver, kidneys and intestine had relatively high concentrations of radioactive compounds, whereas the testes and fat-pads had the lowest concentrations.