Induction of rat liver microsomal epoxide hydrolase by thiazole and pyrazine: hydrolysis of 2-cyanoethylene oxide

Liver microsomal epoxide hydrolase (mEH) is active in the detoxificationof epoxide-containing carcinogens. The effects of thiazole andpyrazine, constituents of tobacco and tobacco smoke as wellas of a variety of foods, on the expression and regulation ofmEH were examined in rats (200 mg/kg body wt/day, i.p., 1/emdash3 days). Immunoblot analyses using rabbit anti-rat mEH antibodyrevealed a significant increase in mEH levels in hepatic microsomesisolated from either thiazole- or pyrazine-treated animals.Another protein (43 kd) cross-reacting with polyclonal mEH antibodywas found to be increased concomitantly following pyrazine treatment.Northern and slot blot analyses showed substantial increasesin mEH mRNA following either thiazole or pyrazine treatment.The level of mEH mRNA increased 17-fold at 24 h following thiazoletreatment, relative to control. Approximately 20- and 16-foldincreases in mEH mRNA were also observed at 48 and 72 h respectivelyfollowing treatment with pyrazine. The level of polymerase chainreaction (PCR)-amplified mEH DNA derived from poly(A)+ RNA wasclearly elevated following either thiazole or pyrazine treatmentrelative to that from untreated animals. Both sense and antisensestrands of PCR-amplified mEH DNA were cloned into an M13mpl9phage vector in order to examine the nucleotide sequences ofPCR-amplified mEH DNA derived from the poly(A)+ RNA isolatedfrom thiazole- or pyrazine-treated animals. Sequence analysesrevealed that the sequence of PCR-amplified DNA from the inducedmRNA was identical to that published for mEH cDNA. Epoxide hydrolaseactivity toward the hydrolysis of 2-cyanoethylene oxide (CEO),the epoxide metabolite of the rat carcinogen acrylonitrile,was not significant in hepatic microsomes from untreated rats,but was substantially induced by treatment with thiazole orpyrazine. Microsomal hydrolysis activity was heat-sensitiveand potently inhibited by l, l, l-trichloropropene-2, 3-oxide,indicating that mEH was the catalyst. The V_max for the hydrolysisof CEO by hepatic microsomes from thiazole-treated rats (13.4nmol/min/mg protein) was 1.5-fold greater than that with microsomesfrom pyrazine-treated rats, whereas similar K_m values ( 1 mM)were observed for both microsomal preparations. These kineticdata correlate well with the increases in mEH mRNA observedafter administration of thiazole or pyrazine to rats. Theseresults provide evidence that administration of thiazole orpyrazine induces mEH with a large increase in mEH mRNA, andthat the induced mEH catalyzes the hydrolysis of CEO.     

Characterization of the bisphosphonate recognition site on hydroxyapatite using radioligand binding techniques with [14C]citric acid

Summary The present studies characterize the binding of [¹⁴C]citric acid to synthetic hydroxyapatite (HA) crystals. [¹⁴C]Citric acid specifically bound to HA and was dependent upon the concentration of HA in the assay. The binding of [¹⁴C]citric acid to HA reached equilibrium within 20 min and remained stable for at least 90 min. Dissociation of bound [¹⁴C]citric acid was biphasic in nature since both rapid and more slowly reversible binding components were detected. Saturation experiments also indicated that [¹⁴C]citric acid labeled two recognition sites with different affinity (Kd_H=42 nM and Kd_L=24,000 nM) and density (Bmax_H=161 fmol/g HA and Bmax_L=8.8 pmol/g HA). Ligand competition experiments revealed that compounds that are known to readily bind bone (e.g., sodium pyrophosphate, methylene diphosphonic acid, etidronate) potently inhibited the binding of [¹⁴C]citric acid to HA, whereas compounds known to have poorer affinity for bone (e.g., oxalic acid and GABA) did not. Computer analysis of these inhibition curves revealed specific ligand interactions at two different affinity recognition sites. The present results indicate that [¹⁴C]citric acid binds discrete sites on synthetic HA in a fashion consistent with a specific labeling of the bisphosphonate recognition site. Analysis of the binding of [¹⁴C]citric acid to HA provides a useful method to further explore the structure activity relationships of novel compounds that have binding affinity for bone.     

Deal nets hospital a 'free' medical building

A developer is about to break ground on a $6.2 million medical office building on land owned by a California hospital. The deal will result in a haven for referral physicians at no cost to the hospital, though it will forgo equity and some management control.     

Rurals using new techniques to finance long-term care

As the population of rural America ages, rural hospitals are seeing opportunities for new revenue in long-term care. To meet those needs, they are turning to tax-exempt revenue bonds, something they rarely used in the past, and private venture capital, an entirely new wrinkle.     

A six-year follow-up study of childhood behavior problems

In order to study the outcome of childhood behavior problems and to investigate relationships between those behavior problems and mental health problems in later years, a survey which was conducted in 1977 was repeated after six years. Subjects were randomly selected children aged from three to seven years living in Bunkyo-ku in Tokyo in 1977. Out of 279 children, responses to the questionnaire were obtained for 201 children, with 39 refusing to co-operate and 39 having left the area. The main results were as follows: 1. Comparison of prevalence rates of individual behavior problems occurring in early childhood (from 3 to 7 years old), showed that behaviors such as overactivity, "difficult to control", persistence, stubbornness and poor relations with unfamiliar persons decreased rapidly with age. On the other hand, hypoactivity, withdrawal and shyness increased. For problems occurring in late childhood (from 9 to 13 years old), the prevalence of poor concentration and passive behavior problems increased with age, while aggressive behaviors decreased. Behaviors such as thumb-sucking, nail-biting, bed-wetting and tics decreased. 2. Over the six years of this study, many behavior problems in areas of activity, mood, volition, human relations and abnormal symptoms showed significant persistence, although the degree of the persistence was not very strong. 3. Significant relationships between behavior problems observed at age three to seven years and mental health problems such as refusal to attend school and antisocial behaviors after six years were not seen.     

Sexual dysfunction in male and female patients with epilepsy: A study of 86 outpatients

Sexual dysfunction is a well-known complication of chronic somatic illness. Eighty-six consecutive epileptic outpatients, 38 men and 48 women, without accompanying disorders, were studied. The frequency and symptoms of sexual dysfunction were compared with results from previous studies using identical sexological methodology. The previous studies were of diabetic patients and healthy controls. Eight percent of the epileptic men reported a sexual dysfunction compared to 44% of the diabetics and 13% of the controls. Epileptic women, diabetic women, and controls showed no significant differences in sexual dysfunction (29%, 28%, and 25%, respectively). In both sexes, the sexual function measured by frequencies of coitus and masturbation was normal. Most patients had good control of epileptic attacks on a treatment of monotherapy. Hormonal status was generally within normal limits in both men and women; only a few minor differences were found and they showed no correlation with sexual dysfunction. Psychologically and socially the patients did not differ appreciably from normals, and they exhibited a high degree of disease acceptance. This study, using a biopsychosocial approach in understanding sexual dysfunctions, is in contrast with previous, mainly uncontrolled, studies of epileptic patients that reported high frequencies of hyposexuality in males. We conclude that epilepsy does not necessarily increase the risk of sexual dysfunction in male or female.     

Tumult, triumphs and turning points. Year of cuts, gains and reform proposals sets the stage for '91

It was a year of decisive wins and losses, a year that for many healthcare organizations signaled a turning point. The resignation of AHA President Carol McCarthy, a Supreme Court decision on Medicaid payments and myriad proposals for healthcare reform were among the events setting the stage for 1991.     

Reprieve ends; hospital margins slide in 1989 as costs climb, debt bill grows

Hospital profitability dipped once again in 1989 after a one-year reprieve from a pattern of sinking margins that has developed since 1985, according to an annual study published by Deloitte & Touche and Health Care Investment Analysts.