Potent and selective inhibition of human nitric oxide synthases. Inhibition by non-amino acid isothioureas

S-Ethylisothiourea was a potent competitive inhibitor of human nitric oxide synthase (NOS), with Ki values of 17, 36, and 29 nM for the inducible (i), endothelial (e), and neuronal (n) isozymes, respectively. Unlike some potent inhibitors of NOS, no time dependence was observed. S-Ethylisothiourea was not a detectable substrate for eNOS. S-Ethylisothiourea was also a potent inhibitor of mouse iNOS (Ki value of 5.2 nM), and its binding perturbed the spectrum of iNOS consistent with its altering the environment of the bound heme. The optimum binding of S-ethyl- and S-isopropylisothiourea relative to 70 other analogs suggested that these alkyl substitutions fit into a small hydrophobic pocket. Most isothioureas were 2-6-fold selective for the human iNOS (Ki for iNOS versus Ki for eNOS), with one being 19-fold selective. The cyclized mimics of S-ethylisothiourea, 2-NH2-thiazoline, and 2-NH2-thiazole, were also competitive inhibitors of human NOS. A third structural class of inhibitors, bisisothioureas, were, in general, the most selective in their inhibition of human iNOS. S,S'-(1,3-Phenylenebis(1,2-ethanediyl))bisisothiourea was 190-fold selective (Ki value of 0.047 microM against iNOS versus 9.0 microM against eNOS). These results demonstrate that potent and selective inhibition of human NOS isozymes is achievable.

Radon in outdoor air in Nevada

Measurements of radon at 50 sites with varying geology indicate that outdoor air in Nevada is comparable to that measured nationwide by Hopper et al. (1991). The statewide median of 15 Bq m-3 (0.4 pCi L-1) is essentially the same as the nationwide median. The range is considerable: from 2.6-52 Bq m-3 (0.07-1.40 pCi L-1). Variations in these measurements can generally be correlated with different concentrations of radon in soils and uranium and its progeny in rocks. Silica-rich igneous rocks (rhyolites and granites) appear to be the main sources of high levels of radon in outdoor air in Nevada. Concentrations of radon in outdoor air generally correlate with levels of radon in soil gas. Measurements taken from heights of 0.5, 1.0, and 2.0 m above the ground suggest that radon in outdoor air reflects the local geology throughout this range of heights. Towns for which > 20% of the homes have indoor-air radon concentrations > 48 Bq m-3 (4 pCi L-1) generally have relatively high soil-gas radon, relatively high outdoor-air radon, or both.

Improvised automatic lung ventilation for unanticipated emergencies

OBJECTIVES

To design an improvised circuit that can be used to extend the capability of a single ventilator to ventilate two or more patients and that can be assembled from readily available parts in times of unanticipated emergency.

DESIGN

Research and development, followed by technical analysis and evaluation.

SETTING

Biomedical laboratory.

MEASUREMENTS AND MAIN RESULTS

We describe two circuits that can be assembled from readily available inexpensive components to function as improvised ventilators. One circuit requires only a central mushroom valve driver and an additional source of fresh gas for each patient. The other circuit is configured as a number of secondary circuits in parallel, connected to a single ventilator. We constructed and tested the circuits using mechanical lung simulators. The secondary circuit configuration was more efficient in terms of fresh gas usage, but was more complex regarding operation and trouble-shooting.

CONCLUSIONS

These two improvised circuits can extend the capability of a standard volume-cycled ventilator to provide automatic ventilation of the lungs in times of disaster.

Characteristics of abstinent substance abusers who first sought treatment in adolescence

A survey was given to 141 male and female substance abusers who had eleven or more months of continuous abstinence and first sought treatment in adolescence in an attempt to add to the limited knowledge of known variables associated with successful adolescent response to clinical and community-based treatment. Results were used to create a composite of successfully abstinent adolescents. Generally, parental alcoholism and most drug use patterns were not related to the number of relapses or length of sobriety. Most of the respondents entered twelve-step programs via treatment. The only two variables that were significantly correlated with the dependent measures of more relapses and less overall sobriety were getting high for the first time at a younger age and polydrug abuse. There were about five times more adoptees represented in this sample than would be statistically expected. Implications for adolescent substance abuse diagnosis and prognosis are discussed.

A rapid biochemical method for measuring antigen-induced pulmonary eosinophil margination in allergic guinea pigs

The ability of purified guinea pig peritoneal eosinophils (EOS) to oxidise 3,3',5,5'-tetramethylbenzidine (TMB) was assessed in the presence/absence of Br- (3 mM), and compared with that of unpurified elicited peritoneal polymorphonuclear leukocytes (PMN). Br- selectively stimulated EOS peroxidase activity in a cell number-dependent manner, which was not significantly affected by the presence of diluted lung homogenate. By comparison with the peroxidase activity of added purified EOS, lung parenchyma homogenate from naive guinea pigs was estimated to contain 1.04 +/- 0.18 x 10(5) cells/mg wet tissue (n = 6), a value comparable to those calculated from published histological analyses. This was not significantly increased by ovalbumin (OA) allergen inhalation in unsensitised guinea pigs (1.4 x 10(5) EOS/mg), but was increased two-fold over the latter control to 3.0 +/- 0.18 x 10(5) cells/mg after 17 h in animals sensitised by a single injection of OA and subsequently exposed to an aerosol of bronchoactive allergen (n = 13, p < 0.05). Similar results were obtained in a parallel study using bronchoalveolar lavage (saline challenge, 20.2 +/- 2.2% EOS in lavage fluid; OA challenge, 47.1 +/- 3.6% EOS; n = 6, p < 0.05). In animals that had been doubly sensitised (two injections) to OA, the pulmonary eosinophilic response measured biochemically was more pronounced (4.9 +/- 0.2 x 10(5) cells/mg) and was significantly greater than both a non-specific protein inhalation in this sensitisation group, and OA inhalation in singly sensitised animals (n = 12, p < 0.05). Sera from the latter group was shown to contain five times less specific anti-OA IgG than the doubly sensitised animals, suggesting that EOS margination in guinea pigs is proportionate to the animals' immune status for a defined immunological challenge. These data demonstrate that in vivo EOS migration into the whole guinea pig lung can be rapidly determined by biochemical methods, and thus facilitate the in vivo assessment of novel therapeutic agents against the eosinophilic inflammation characteristic of human allergic asthma.

Treatment of prostatic bleeding: suppression of angiogenesis by androgen deprivation

Bleeding of prostatic origin is usually caused by the friable hypervascularity of the aging prostate. Suppression of angiogenesis can be achieved through any hormonal manipulation that causes androgen deprivation. We present 4 cases of severe recurrent hematuria treated successfully by this approach.

Cost justifying the electronic billing decision

Many patient accounts professionals have a "gut" feeling that electronic billing systems save hospitals time and money. But they need more than a gut feeling to convince hospital management to invest in such systems. The key is to make some objective financial estimates of the potential impact that electronic billing can have on hospitals.

Mortality and social class in Maori and nonMaori New Zealand men: changes between 1975-7 and 1985-7

AIMS

Social class mortality differences in Maori and nonMaori New Zealand men aged 15-64 years have previously been examined for the period 1975-7. The analysis has now been repeated for the period 1985-7 in order to examine changes over time.

METHODS

Numerator data were obtained from national death registrations and denominator data were obtained from the 1976 and 1986 censuses. These were used to calculate age-standardized death rates in Maori and nonMaori.

RESULTS

Mortality declined by 28% in Maori and 14% in nonMaori between 1975-7 and 1985-7. The death rate for diseases amenable to medical intervention fell by 54% in Maori and 23% in nonMaori, but the Maori death rate was still 2.8 times the nonMaori death rate, whereas the relative risk for nonamenable causes was only 1.4.

CONCLUSIONS

Some progress has been achieved in reducing ethnic differences in mortality in New Zealand men, but substantial differences remain for diseases which are amenable to medical intervention (including chronic rheumatic heart disease, hypertensive heart disease, and tuberculosis). It is likely that these differences reflect poor access to culturally safe and appropriate health care in Maori people.

Morbidity and death due to child abuse in New Zealand

The purpose of this study was to explore under-diagnosis and racial bias among child abuse morbidity and mortality data from New Zealand. Computerized files of all intentional injury fatalities among children 16 years of age and under for 1978-87, and all hospital discharges for intentionally injured children 16 and under for 1988, were analyzed for evidence of physical abuse and sexual abuse. Among the 92 fatalities, only 21 of 68 deaths due to physical and/or sexual abuse were so coded. In both the mortality and the morbidity data, there was an association between the diagnosis of child abuse and race. In the case of fatalities, Maori and Samoan abuse victims were more likely to be assigned an E-code of E967 ("child battering and other maltreatment") than were "others" (p = 0.04), controlling for sex. In the case of hospitalizations, the association between E967 and whether or not the victim was European was significant for physical abuse only (p = 0.05). Assignment of N-code = 995.5 ("child maltreatment syndrome") as the reason for admission was significantly associated with race for those cases considered by us to have been abused, controlling for age (p = 0.002) or sex (p = 0.004).

Mucosal injury and inflammation in a model of chronic granulomatous colitis in rats

BACKGROUND

The objective of this study was to characterize the acute and chronic inflammation induced by the intramural injection of peptidoglycan-polysaccharide (PG-PS) into the distal colon of genetically susceptible rats.

METHODS

Blood-to-lumen clearance of 51Cr-ethylenediaminetetraacetic acid, colonic myeloperoxidase activity, colon weight, and plasma nitrite and nitrate levels were determined to quantitate colonic mucosal injury, inflammation, and nitric oxide (NO) production, respectively.

RESULTS

Intramural injection of PG-PS into the distal colon produced a local biphasic inflammatory response composed of an acute episode 3 days after injection; this was followed by a spontaneous reactivation of chronic granulomatous colitis manifested by colonic thickening, adhesions, and infiltration of the submucosa and muscularis propria with macrophages, neutrophils, and lymphocytes at 3-4 weeks. Mucosal ulcers were evident only at 3 weeks, but hepatic nodules, splenic necrosis, and arthritis were evident at both 3 and 4 weeks after PG-PS injection. PG-PS produced significant increases in colonic mucosal permeability, myeloperoxidase activity, and plasma nitrite and nitrate levels at 3 weeks postinjection compared with controls. PG-PS stimulated the production of nitrite by elicited peritoneal macrophages and neutrophils in vitro.

CONCLUSIONS

PG-PS produces a chronic granulomatous colitis in rats; this colitis is characterized by enhanced NO production.

Homogeneous versus heterogeneous age group treatment of adolescent substance abusers

The treatment outcome from homogeneous age group substance abuse treatment centers, whose clientele consisted primarily of adolescent substance abusers, was compared to heterogeneous age group substance abuse treatment centers, where adolescent and adult patients were treated together. Subjects were 100 substance abusers, from 20 states, who recovered in adolescence and had at least 11 months of continuous abstinence. A 24-item self-report questionnaire was used to ascertain the type of recovery treatment experienced, number of relapses, and duration of sobriety. Results indicated a disproportionate number of substance abusers who recovered in adolescence were treated in a heterogeneous age group clinical setting. There was no significant difference in the length of sobriety and number of relapses between the homogeneous and heterogeneous treatment groups. These data suggest adolescent substance abusers can be treated at a lower cost and with a higher recovery rate by placing them in adult treatment settings.

Treatment paternalism in chemical dependency counselors

This study investigated the degree of paternalism in the treatment philosophies of chemical dependency counselors in three categories of treatment center: adolescent-only, adult, and religious/minority. Counselors were shown picture arrays of either adolescent patients or adult patients and asked to choose a preferred treatment policy, either paternalistic or compensatory in nature. Results showed religious/minority counselors preferred a significantly greater paternalistic approach to all patients than did the adolescent-only and adult center counselors. The adolescent-only counselors responded more paternalistically to the adolescent patients than the adult patients, while the adult and religious/minority counselors did not respond significantly different to either group.

Molecular cloning, cDNA sequence, and bacterial expression of human glutamine:fructose-6-phosphate amidotransferase

Glutamine:fructose-6-phosphate amidotransferase (GFAT) has recently been shown to be an insulin-regulated enzyme that plays a key role in the induction of insulin resistance in cultured cells. As a first step in understanding the molecular regulation of this enzyme the human form of this enzyme has been cloned and the functional protein has been expressed in Escherichia coli. A 3.1-kilobase cDNA was isolated which contains the complete coding region of 681 amino acids. Expression of the cDNA in E. coli produced a protein of approximately 77 kDa and increased GFAT activity 4.5-fold over endogenous bacterial levels. Recombinant GFAT activity was inhibited 51% by UDP-GlcNAc whereas bacterial GFAT activity was insensitive to inhibition by UDP-GlcNAc. On the basis of these results we conclude that: 1) functional human GFAT protein was expressed, and 2) the cloned human cDNA encodes both the catalytic and regulatory domains of GFAT since the recombinant GFAT was sensitive to UDP-GlcNAc. Overall, the development of cloned GFAT molecular probes should provide new insights into the development of insulin resistance by allowing quantitation of GFAT mRNA levels in pathophysiological states such as non-insulin-dependent diabetes mellitus and obesity.

Prooxidant properties of 5-aminosalicylic acid. Possible mechanism for its adverse side effects

There is a growing body of experimental and clinical evidence to suggest that oral or rectal administration of 5-ASA or 5-ASA conjugates is associated with significant adverse side effects including pancreatitis, hepatitis, and renal toxicity. The objective of this study was to assess the ability of 5-ASA to interact with low-molecular-weight iron to yield oxygen-derived free radicals and to determine whether these oxidants could damage model biological compounds. We found that 5-ASA was very effective at chelating ferric iron (Fe3+), and it rapidly reduced Fe3+ to the ferrous form (Fe2+). Addition of the 5-ASA/Fe2+ chelate to solutions containing polyunsaturated fatty acids or deoxyribose resulted in lipid peroxidation and oxidative carbohydrate degradation, respectively. These results are consistent with the formation of the highly reactive (and cytotoxic) hydroxyl radical. Formation of this free radical species was confirmed by the ability of hydroxyl radical scavengers (dimethyl sulfoxide, dimethyl thiourea) to inhibit the 5-ASA/Fe-mediated oxidative reactions. Maximum hydroxyl radical formation was achieved at a 5-ASA-to-Fe3+ ratio of 1.0 (20 microM 5-ASA and 20 microM Fe3+). Increasing this ratio significantly inhibited OH. formation with a concomitant reduction in lipid peroxidation and deoxyribose degradation. Finally, we demonstrated that 5-ASA promotes the reductive release of Fe3+ from ferritin. Data obtained in this study suggest that 5-ASA may, under certain conditions, promote the formation of potentially injurious free radical species. These oxidative reactions may contribute to some of the adverse side effects known to be associated with the newer preparations of 5-ASA.

Nebulized fenoterol causes greater cardiovascular and hypokalaemic effects than equivalent bronchodilator doses of salbutamol in asthmatics

The pulmonary and extrapulmonary effects of two doses of nebulized fenoterol (5 mg) salbutamol (5 mg) and ipratropium bromide (0.5 mg) at 60 min intervals were compared in nine patients with asthma in a double-blind, randomized study. Measurements of heart rate, blood pressure, electromechanical systole (QS2I), QTc interval, FEV1 and plasma potassium were made at baseline and at 15, 30 and 60 min after each nebulization. Both beta-agonists caused significantly greater inotropic (QS2I), chronotropic (HR), electrocardiographic (QTc) and hypokalaemic effects than ipratropium bromide (IB), with fenoterol being more potent than salbutamol. Fenoterol had no greater effect on FEV1 than salbutamol although both were superior to IB. Only the first four subjects had two doses as originally intended, because the second administration of fenoterol resulted in marked cardiovascular effects and hypokalaemia. The observed differences in extrapulmonary effects between fenoterol and salbutamol provide a plausible group of mechanisms which may explain the increased risk of death associated with fenoterol in severe asthmatics.

Impairment of left ventricular diastolic function in systemic lupus erythematosus

Left ventricular (LV) diastolic performance was evaluated with pulsed-wave Doppler echocardiography in a cross-sectional population of patients with systemic lupus erythematosus (SLE) in search of subclinical myocardial involvement. Such involvement is reported to occur infrequently, despite pathohistologic evidence of myocarditis in up to 70% of patients with SLE. Thirty-five consecutive patients with SLE were evaluated, 14 with active and 21 with inactive disease, and were compared with 30 age-matched healthy control subjects. Twenty-six patients were restudied at 7 months. All had normal LV systolic function, normal pericardial and valvular structures, and no significant valvular regurgitation on Doppler echocardiography. In SLE patients with active disease, indexes of LV diastolic function differed significantly from the inactive group and from control subjects, with marked prolongation of isovolumic relaxation time (104 +/- 18 vs 74 +/- 13 ms, p = 0.0001), as well as reduced peak early diastolic filling velocity (E) (0.69 +/- 0.19 vs 0.83 +/- 0.17 ms, p = 0.01), reduced ratio of early to late diastolic flow velocity (E/A) (1.15 +/- 0.53 vs 1.47 +/- 0.35, p = 0.02), and prolonged mitral pressure halftime (74 +/- 14 vs 65 +/- 8 ms p = 0.01). Similar significant differences were found between the active and inactive SLE patient groups. SLE patients with inactive disease differed from control subjects in only mild prolongation of mitral pressure halftime. Abnormal prolongation of isovolumic relaxation (greater than 100 ms) was found to be the most useful marker of diastolic impairment, being present in 64% of SLE patients with active disease and in 14% of patients with inactive disease.(ABSTRACT TRUNCATED AT 250 WORDS)