Hyperoxia induces DNA damage in mammalian cells.

There is mounting evidence on the role of oxygen-derived free radicals in causing damage to various cellular components. However, most studies reported in the literature have been conducted under conditions where cells were challenged with chemical free radical generating systems. In contrast, we measured DNA strand breaks, through a relatively simple and sensitive technique, as a function of the dissolved oxygen tension in a bioreactor. Cells were exposed to a step change in oxygen tension at mid-exponential growth phase. Several levels of oxygen were tested (200, 300, and 476% dissolved oxygen with respect to air saturation at 1 atmosphere) and compared against a control (10% dissolved oxygen). Hyperoxia was found to cause monotonically increasing DNA strand breakage at all the oxygen levels. In addition, hyperoxia was found to affect other metabolic functions such as the glucose consumption rate, lactate production rate, and cell growth. When hyperoxia-induced DNA strand breakage was compared to that induced by exposure to hydrogen peroxide, a similar response was observed. Exposure to a dissolved oxygen level of 200% induced DNA strand breakage comparable to a bolus of 4.2 microM hydrogen peroxide. Our results show that there is an association between hyperoxia and DNA damage.

DNA base modifications and membrane damage in cultured mammalian cells treated with iron ions.

We investigated DNA base damage in mammalian cells exposed to exogenous iron ions in culture. Murine hybridoma cells were treated with Fe(II) ions at concentrations of 10 microM, 100 microM, and 1 mM. Chromatin was isolated from treated and control cells and analyzed by gas chromatography/mass spectrometry for DNA base damage. Ten modified DNA bases were identified in both Fe(II)-treated and control cells. The quantification of modified bases was achieved by isotope-dilution mass spectrometry. In Fe(II)-treated cells, the amounts of modified bases were increased significantly above the background levels found in control cells. Dimethyl sulfoxide at concentrations up to 1 M in the culture medium did not significantly inhibit the formation of modified DNA bases. A mathematical simulation used to evaluate the plausibility of DNA damage upon Fe(II) treatment predicted a dose-dependent response, which agreed with the experimental results. In addition, Fe(II) treatment of cells increased the cell membrane permeability and caused production of lipid peroxides. The nature of DNA base lesions suggests the involvement of the hydroxyl radical in their formation. The failure of dimethyl sulfoxide to inhibit their formation indicates a site-specific mechanism for DNA damage with involvement of DNA-bound metal ions. Fe(II) treatment of cells may increase the intracellular iron ion concentration and/or cause oxidative stress releasing metal ions from their storage sites with subsequent binding to DNA. Identified DNA base lesions may be promutagenic and play a role in pathologic processes associated with iron ions.

Help-seeking for intimate partner violence and forced sex in South Carolina.

PURPOSE: In this population-based, random-digit-dial, cross-sectional survey, we assessed the lifetime victimization of intimate partner violence (IPV) and forced or coerced sex among 556 women and men in South Carolina, and the help-seeking behaviors of victims. RESULTS: Among women, 25.3% experienced IPV (sexual, physical, or emotional violence) compared with 13.2% of men. Although women were significantly more likely to report physical or sexual IPV (17.8%) than were men (4.9%), men (8.3%) were as likely as women (7.4%) to report perceived emotional abuse without physical or sexual IPV. One half of men and women with annual incomes <$15, 000 reported IPV. Among women experiencing physical or sexual IPV, 53% sought community-based or professional services for IPV; women with higher education levels and those experiencing more severe violence were most likely to seek services. CONCLUSIONS: These data show that IPV is common and that most victims do not receive services to address this violence.

Excess hospital admissions during the July 1995 heat wave in Chicago.

INTRODUCTION: This study describes medical conditions treated in all 47 non-VA hospitals in Cook County, IL during the 1995 heat wave. We characterize the underlying diseases of the susceptible population, with the goal of tailoring prevention efforts. METHODS: Primary and secondary discharge diagnoses made during the heat wave and comparison periods were obtained from computerized inpatient hospital discharge data to determine reasons for hospitalization, and comorbid conditions, respectively. RESULTS: During the week of the heat wave, there were 1072 (11%) more hospital admissions than average for comparison weeks and 838 (35%) more than expected among patients aged 65 years and older. The majority of this excess (59%) were treatments for dehydration, heat stroke, and heat exhaustion; with the exception of acute renal failure no other primary discharge diagnoses were significantly elevated. In contrast, analysis of comorbid conditions revealed 23% (p = 0.019) excess admissions of underlying cardiovascular diseases, 30% (p = 0.033) of diabetes, 52% (p = 0.011) of renal diseases, and 20% (p = 0.027) of nervous system disorders. Patient admissions for emphysema (p = 0.007) and epilepsy (p = 0.009) were also significantly elevated during the heat wave week. CONCLUSIONS: The majority of excess hospital admissions were due to dehydration, heat stroke, and heat exhaustion, among people with underlying medical conditions. Short-term public health interventions to reduce heat-related morbidity should be directed toward these individuals to assure access to air conditioning and adequate fluid intake. Long-term prevention efforts should aim to improve the general health condition of people at risk through, among other things, regular physician-approved exercise.

Structural damage to lactate dehydrogenase during copper iminodiacetic acid metal affinity chromatography.

The stability of the enzyme lactate dehydrogenase (LDH) was evaluated by measuring structural damage and activity loss after exposure to copper-iminodiacetic acid (IDA) immobilized metal affinity chromatography (IMAC) under oxidizing conditions at pH 7.0. Oxidizing conditions were produced by adding reductants commonly employed in bioprocessing and biomedical applications (glutathione, beta-mercaptoethanol, dithiothreitol, cysteine, or ascorbate) and/or hydrogen peroxide to the mobile phase. Most of these additives have been shown recently to give rise to metal-catalyzed oxidation (MCO) reactions on copper-iminodicaetic acid IMAC columns. Structural damage in the form of increased susceptibility to proteolytic degradation, fragmentation, and cross-linking were measured. Increased sensitivity to proteolysis was significant in virtually all cases tested, even when activity remained high (>95% specific activity recovered). In contrast fragmentation and cross-linking were minimal in all cases, even when activity was low (<50%). As the damage was believed to have been caused primarily by MCO reactions, preventative measures consistent with this reaction pathway were tested. The most successful measure for all of the conditions studied was addition of the Cu+ chelating agent bicinchoninic acid (BCA) to the mobile phase. Decreased contact time with the column decreased damage in the case where glutathione was added. Removal of dissolved oxygen by nitrogen sparging and use of Tris-acetate buffer in place of phosphate had no measurable effect. The success of BCA addition in reducing structural damage and activity loss strengthens the conclusion that MCO reactions can occur on copper-iminodiacetic acid IMAC columns. However, the addition of BCA and the other protective measures described were not successful in eliminating the increased proteolytic susceptibility observed when LDH in buffer was exposed to the copper-charged column with no oxidizing additives. This suggests that at least one other pathway for damage exists. This damage is difficult to detect as it did not cause statistically significant losses in enzymatic activity, fragmentation, or cross-linking.

tert.-butyl hydroperoxide-mediated DNA base damage in cultured mammalian cells.

tert.-Butyl hydroperoxide has been utilized to study the effect of oxidative stress on living cells; however, its effect on DNA bases in cells has not been characterized. In the present work, we have investigated DNA base damage in mammalian cells exposed to this organic hydroperoxide. SP2/0 derived murine hybridoma cells were treated with 4 concentrations of tert.-butyl hydroperoxide for varying periods of time. Chromatin was isolated from treated and control cells and subsequently analyzed by gas chromatography-mass spectrometry with selected-ion monitoring for DNA base damage. Quantification of damaged DNA bases was achieved by isotope-dilution mass spectrometry. The amounts of 8 products were significantly higher than control levels in cells treated with tert.-butyl hydroperoxide at a concentration range of 0.01-0.1 mM. At concentrations from 1.0 to 10 mM, product formation was inhibited and the amounts of products were similar to those in control cells. The bimodal nature of the dose-response may be qualitatively analogous to previous reports of bimodal killing of E. coli bacteria by hydrogen peroxide. The nature of the identified DNA base lesions suggests the involvement of the hydroxyl radical in their formation. tert.-Butyl hydroperoxide is known to produce the tert.-butoxyl radical in reactions with metal ions. However, it is unlikely that the tert.-butoxyl radical produces these DNA lesions. It is suggested that DNA base damage arises from tert.-butyl hydroperoxide-mediated oxidative stress in cells, resulting in formation of hydroxyl radicals in close proximity to DNA. The inhibition of product formation at high concentrations of tert.-butyl hydroperoxide may be explained by the scavenging of tert.-butoxyl radical by tert.-butyl hydroperoxide resulting in inhibition of oxidative stress. The plausibility of the scavenging mechanism was evaluated with a mathematical simulation of the dose-response for DNA damage in solutions containing hydrogen peroxide. The simulation model predicted a bimodal dose-response which agreed qualitatively with the results in this study and with other in vivo and in vitro studies reported in the literature.

Analysis of Hispanic motor vehicle trauma victims in Illinois, 1991-1992.

OBJECTIVE: 1) To develop a profile of Hispanic motor vehicle trauma victims in Illinois, 2) to ascertain whether differences exist between Hispanic and general-Illinois-population motor vehicle trauma victims, and 3) to identify potential target areas for future injury intervention programs. METHODS: A retrospective analysis of Illinois motor vehicle trauma patients admitted from July 1991 to June 1992 was made. Participants were motor vehicle trauma victims (drivers and passengers) who presented to one of 73 level I or level II trauma centers throughout Illinois and were entered into the Illinois Trauma Registry (ITR) from July 1, 1991, through June 30, 1992. RESULTS: Of the 12,299 motor vehicle trauma victims in the ITR, 771 (6.3%) were Hispanic, 8,979 (73.0%) were white, 1,115 (9.1%) were black, and 1,434 (11.6%) were other. When compared with the other racial groups, the group of Hispanic victims were younger (25.2 vs 33.2 years), had higher male predominance (72.8% vs 60.9%), and had the lowest rate of safety equipment/occupant restraint use (21.7% vs 34.7%). A high alcohol use rate (30.7%) and high mean serum ethanol levels (44 mmol/L; 0.2 mg%) were noted. When contrasted with other racial/ethnic groups, the Hispanic victims had lower Injury Severity Scale scores (p < 0.001), but mean hospital charges tended to be higher, with fewer alternative sources of payment (p < 0.001). CONCLUSION: Using age-adjusted data from the ITR, Hispanic motor vehicle trauma victim features differ significantly from those of other racial groups. Effective health maintenance and injury prevention strategies should address the basis for these differences.

Inactivation of lysozyme by sonication under conditions relevant to microencapsulation.

Controlled release dosage forms of proteins and other biomolecules can be prepared by microencapsulating them in polymeric microspheres. Proteins are subjected to potentially damaging effects of sonication and exposure to organic solvents during the microencapsulation process. The relatively stable enzyme lysozyme was dissolved in aqueous buffer and sonicated in the presence of methylene chloride to mimic the initial step of the microencapsulation process. The stability of lysozyme was evaluated by determining the enzyme activity before and after sonication, size-exclusion chromatography, native polyacrylamide gel electrophoresis, and by measuring the amount of precipitates formed. Following sonication, the total protein introduced was distributed between a soluble and an insoluble fraction. Sonication of lysozyme solutions in the presence of methylene chloride led to an increase in precipitates. The precipitates were enzymatically inactive, did not dissolve easily, and were held by non-covalent interactions. No fragments or aggregates of lysozyme were detectable in the soluble fraction. Sonicating aqueous lysozyme solutions with and without methylene chloride decreased the specific activity of the enzyme in the soluble fraction. Excipients such as dimethyl sulfoxide (DMSO), mannitol, sucrose, and tween 80 were included in the sonication mixtures containing lysozyme. With the exception of tween 80, the addition of the excipients to aqueous solutions of lysozyme led to a greater decrease in the specific activity of lysozyme when sonicated in the presence of methylene chloride. DMSO caused the greatest loss of enzyme activity following sonication. Sonication of lysozyme with water, methylene chloride, and DMSO yielded methyl radicals, which were trapped with alpha-phenyl N-tert-butylnitrone and detected by ESR spectroscopy.

Limitations of qualitative serum beta-HCG assays in the diagnosis of ectopic pregnancy.

Seventy-four patients had ectopic pregnancies proven by surgery. Three of them had a serum beta-HCG test for pregnancy that was reported as negative (less than 25-35 mIU/ml). We sought a threshold for positive in the serum beta-HCG test that would maximize its usefulness in diagnosing ectopic pregnancy. Sera from 52 of the patients were available for reanalysis. Quantitative values of beta-HCG were determined. Lowering the threshold for positive from 25-35 to 10 mIU/ml might increase the test's sensitivity without sacrificing specificity but would still not ensure detection of all ectopic pregnancies. Of 445 cases of ectopic pregnancy described in the literature, 6 had serum beta-HCG values reported as negative. In the published reports and in our own cases, clinical histories and histologies indicated that a nonviable ectopic pregnancy can be expected to have an associated serum concentration of beta-HCG that may be below the sensitivity of detection even with current, commercially available quantitative tests.

A 33-year-old white female with abdominal pain, nausea, vomiting and hypotension.

A thirty-three year old female presented to our emergency department complaining of severe abdominal pain, nausea, and vomiting. On physical examination she was hypotensive with a firm, tender abdomen, cervical motion tenderness and a diffuse erythematous rash. A surgical diagnosis of Acute Pelvic Inflammatory Disease was made during laparoscopy. Coagulant studies, liver function tests, culture results, and the desquamation of the patient's palms led to the additional diagnosis of Toxic Shock Syndrome. A literature search failed to reveal any similar cases of Pelvic Inflammatory Disease (PID) and Toxic Shock Syndrome (TSS) occurring concomitantly. Patients may present severely ill with either of these disease entities but potential for serious illness is greater when both of these syndromes occur in the same patient. We conclude that in patients with a similar presentation, the symptoms should not be attributed completely to PID without further investigation and consideration of a concomitant disease process including TSS.

The effect of prehospital transport time on the mortality from traumatic injury.

OBJECTIVE: To test the hypothesis that a prehospital time threshold (PhTT) exists that when exceeded, significantly increases the mortality of trauma patients transported directly from the scene of injury to a trauma center rather than to the closest hospital. DESIGN: Review of data contained within the Illinois Trauma Registry encompassing the period from fall 1989 through spring 1991. PARTICIPANTS: A total of 5,215 injured persons with an Injury Severity Score (ISS) > 10, cared for in an Illinois level-I or -II trauma center outside of the city of Chicago. MEASUREMENTS: Injury severity expressed as ISS, scene time (ST), transport time (TrT), total emergency medical services time (TEMST), and outcome were determined for each patient. Patients were stratified into groups on the basis of ISS. RESULTS: Patient outcomes were significantly different statistically between ISS groups (p < 0.001, chi 2). Mean ST and TEMST, but not TrT, were significantly different statistically between ISS groups (p < 0.001, analysis of variance). Lower ISS was associated with longer times. Mean ST, TrT, and TEMST were significantly different statistically between survivors and nonsurvivors (p < 0.001, two-sample t-tests). Survival was associated with longer times. Each of the mean times remained significantly different between survivors and nonsurvivors after controlling for severity of injury (p < 0.001, two-way analysis of variance). CONCLUSION: No PhTT beyond which time patient transport to the closest hospital would have decreased mortality was identifiable, because no prehospital time < 90 minutes exerted a significant adverse effect upon survival.

Relationship between optimism and coping strategies in the work environment.

The work environment is often stressful; however, the specific coping strategies used by individuals to deal with such stress have received limited attention. While the benefits associated with optimism have long been touted, little insight has been developed regarding the mechanism(s) that may contribute to optimists' superior job performance. It is possible that optimism is associated with higher performance because it influences the coping strategies used by salespeople. This possibility was addressed in a cross-sectional study of 101 salespeople. Dispositionally optimistic salespersons were observed to rely more on problem-focused coping strategies, while pessimists engaged in emotion-focused coping. But the specific coping tactics that emerged and the extent to which these tactics were used differed substantially from those which research conducted in other, nonsales settings would have predicted.

Stability of the isolation/disengagement relationship across age groups.

Research has indicated isolated elderly persons are either engaged or voluntarily disengaged. The present assessment was whether this relationship holds across age subgroups. While the general relationship did hold true for all age groups, the 55-64 age group was less engaged than their older cohorts. The level and type of disengagement appears to be dependent upon life situations and can decrease with age.

Psychology of computer use: XXV. Locus of control, information-system dialogues, and end-users' satisfaction.

This study examined the correlation of locus of control and end-users' satisfaction for three computer dialogue treatments--question/answer, menu, and command language. In the present study, 390 subjects were classified as internally or externally oriented according to an abbreviated form of Rotter's I-E Scale. Subjects then utilized an information system possessing one of three randomly selected dialogues to solve a problem in selecting employees. Their over-all satisfaction with the system was measured. Analysis of variance did not support the hypothesis that locus of control is associated with users' satisfaction.

Air, water, places, and data--public health in the information age.

This article discusses the implications of the Health Insurance Portability and Accountability Act of 1996, the National Health Information Infrastructure project of the National Committee on Vital and Health Statistics, and other standard development initiatives for future public health information systems.

Six principles of public health information.

The collection and analysis of data has been a fundamental activity of public health since the earliest times. Automated systems have enabled public health agencies to accumulate vast amounts of data. This data becomes useless without a systematic approach to convert it into information that directs action. Public health systems that manage service delivery should be integrated to maximize efficiency and minimize burdens upon program staff.