Biochemical indices of selected trace minerals in men: effect of stress.

Plasma zinc, iron, copper, and selenium and selected blood proteins were measured in 66 men before (BHW) and after (AHW) a 5-d period of sustained physical and psychological stress called Hell Week. Recovery blood samples were obtained from 26 men 7 d after Hell Week. Dietary intakes were determined BHW and during Hell Week; zinc, iron, copper, and selenium intakes during Hell Week averaged 23.6 +/- 3.4 mg/d, 35.4 +/- 3.9 mg/d, 3.0 +/- 0.5 mg/d, and 92.5 +/- 26.7 micrograms/d, respectively. C-reactive protein was detected in only five subjects BHW and in all subjects AHW. Zinc, iron, selenium, and albumin decreased by 33%, 44%, 12%, and 9%, respectively, whereas ferritin, ceruloplasmin, and creatine kinase concentrations increased AHW by 59%, 8%, and 266%, respectively. Haptoglobin concentrations increased 57% in 30 subjects but decreased 32% in 23 subjects AHW. The biochemical changes were transitory because protein (except ferritin) and mineral concentrations were similar to BHW values 7 d after Hell Week. Hell Week induced changes characteristic of an acute-phase response in physically active men.

Plasma pyridoxal and pyridoxal 5'-phosphate concentrations in response to ingestion of water or glucose polymer during a 2-h run.

The effects of ingesting a glucose polymer solution (GP) or water (W) on plasma pyridoxal 5'-phosphate (PLP) and pyridoxal (PL) concentrations were compared in six men (age: 30 +/- 2 y; VO2max: 57.4 +/- 3.2 mL.kg-1.min-1) under running (R) and control (C) conditions. Subjects ran for 2 h at 60-65% of VO2max for R and remained standing for C. For both R and C, 200 mL W or GP was ingested before (0-time) and every 30 min while running (30, 60, and 90 min). Plasma PLP decreased to 95% and 87% of 0-time at 180 min for WC and GPC and increased to 126% and 119% at 90 min and to 124% and 119% at 120 min for WR and GPR. By 60 min postrun, plasma PLP was 98% (WR) and 101% (GPR) of 0-time. There were no significant differences between W and GP conditions. Changes in PLP were not related to plasma volume or blood glucose, free fatty acids, lactate, alkaline phosphatase, aspartate aminotransferase, or alanine aminotransferase. No significant changes in plasma PL were noted. Exercise induces an increase in plasma PLP, perhaps due to transfer of B-6 vitamers from liver to skeletal muscle.

Variability of responses across training levels to maximal treadmill exercise.

The variability of peak VO2 (ml/min, ml.kg-1.min-1), time on treadmill (TMILLTM), maximal heart rate (HRmax), respiratory exchange ratio at peak VO2 (Rmax), rate of respiration at peak VO2 (FREQ), and exercise-induced changes in plasma lactate concentration (LACDIF) was measured across three maximal treadmill runs in five highly trained, seven moderately trained, and five untrained males. No effect of training level on the variability of any of the parameters was found. Test-retest correlation coefficients for peak VO2 (r = 0.95, run 1 with run 2; r = 0.92, run 1 with run 3; r = 0.92, run 2 with run 3) were similar to previously reported values. Variance component distributions suggested that the underlying physiological mechanisms of response for peak VO2, TMILLTM, and HRmax were different from those of FREQ, Rmax, and LACDIF. Minimum detectable differences for peak VO2 (ml.kg-1.min-1, n = 5, minimum detectable within subject difference, 11.5%; minimum detectable among subject effects, 21.3%) indicated a need for careful attention to research design in future studies.

Prolonged whole-body cold water immersion: fluid and ion shifts.

To characterize fluid and ion shifts during prolonged whole-body immersion, 16 divers wearing dry suits completed four whole-body immersions in 5 degrees C water during each of two 5-day air saturation dives at 6.1 msw. One immersion was conducted at 1000 (AM) and one at 2200 (PM) so that diurnal variations could be evaluated. Fifty-four hours separated the immersions, which lasted up to 6 h; 9 days separated each air saturation dive. Blood was collected before and after immersion; urine was collected for 12 h before, during, and after immersion for a total of 24 h. Plasma volume decreased significantly and to the same extent (approximately 17%) during both AM and PM immersions. Urine flow increased by 236.1 +/- 38.7 and 296.3 +/- 52.0%, urinary excretion of Na increased by 290.4 +/- 89.0 and 329.5 +/- 77.0%, K by 245.0 +/- 73.4 and 215.5 +/- 44.6%, Ca by 211.0 +/- 31.4 and 241.1 +/- 50.4%, Mg by 201.4 +/- 45.9 and 165.3 +/- 287%, and Zn by 427.8 +/- 93.7 and 301.9 +/- 75.4% during AM and PM immersions, respectively, compared with preimmersion. Urine flow and K excretion were significantly higher during the AM than PM. In summary, when subjects are immersed in cold water for prolonged periods, combined with a slow rate of body cooling afforded by thermal protection and enforced intermittent exercise, there is diuresis, decreased plasma volume, and increased excretions of Na, K, Ca, Mg, and Zn.

Plasmodium vivax infections in U.S. Army troops: failure of primaquine to prevent relapse in studies from Somalia.

Different strains of Plasmodium vivax vary in their sensitivity to primaquine, the only drug that prevents relapses. Described are the clinical data and relapse pattern for 75 soldiers treated for vivax malaria since returning from Somalia. Following their initial attack of malaria, 60 of the 75 cases received a standard course of primaquine (15 mg base daily for 14 days). Twenty-six of the 60 soldiers subsequently relapsed for a failure rate of 43%. Eight soldiers had a second relapse following primaquine therapy after both the primary attack and first relapse. Three of these soldiers had received a higher dosage of primaquine (30 mg base daily for 14 days) after their second attack. The apparent ineffectiveness of primaquine therapy in preventing relapses suggests the presence of primaquine-resistant P. vivax strains in Somalia.

Laboratory evaluation of a dot-blot enzyme immunoassay for serologic confirmation of illness due to Rickettsia conorii.

Of the 169 United States Army soldiers who deployed on a field training exercise to a remote area of Botswana for two weeks in January 1992, more than 30% developed a febrile illness within five days of their return. A diagnosis of South African tick typhus was suggested by soldiers' exposure to ticks, as well as the presence of eschars and vesicles at the site of tick bites, and tender regional lymphadenopathies. This high attack rate, experienced during such a short exposure period, emphasizes the hazard of illness due to Rickettsia conorii to persons visiting endemic areas. A rapid, diagnostic, semiquantitative enzyme immunoassay (DS) for detection of IgG and IgM antibodies to R. conorii was performed on 209 acute and convalescent sera from soldiers in the outbreak and on 75 control sera. For the acute sera from soldiers meeting the probable case definition of having both regional lymphadenopathy and tick bite eschar, as judged by an IgG indirect fluorescent antibody (IFA) test, the resulting sensitivity and specificity of the DS test were 100% and 48%, respectively. In the analysis of the acute sera, the DS test identified as reactive more of the probable cases (62%) than either the IgG (16%) or IgM (55%) IFAs. This simple and rapid diagnostic test could be useful in establishing a preliminary diagnosis of R. conorii rickettsiosis in remote settings when immediate confirmation by IFA is impossible.

Detection of PCR products of the ipaH gene from Shigella and enteroinvasive Escherichia coli by enzyme linked immunosorbent assay.

PCR techniques applied to diarrheal stools reliably diagnose Shigella and enteroinvasive Escherichia coli (EIEC) infections. Identification of PCR products using agarose gel electrophoresis (AGE) and hybridization with DNA probes has several shortcomings. Automated methods of identifying PCR products that process larger numbers of specimens can facilitate epidemiologic studies and standardize results. In this study, we used ELISA following PCR to detect ipaH gene sequences of Shigella and EIEC from 89 diarrheal stools. Results of ELISA were compared with AGE with and without DNA probe, and with culture. Two specimen preparation methods were compared as well: boiling/centrifugation, and purification with silicon dioxide (SiO(2)). Both PCR product-detection methods identified significantly more infections than did culture. PCR-ELISA detected significantly more infections than PCR-AGE when processed using SiO2 (P = 0.014). PCR-ELISA allows screening of larger numbers of specimens, automates test results, and avoids use of mutagenic reagents. PCR-ELISA is faster than PCR-AGE when testing large numbers of specimens, although not when testing small numbers of specimens.

Plasma zinc uptake from a supplement during submaximal running.

The uptake of zinc (Zn) into the plasma after the ingestion of 25 mg of Zn from multivitamin-mineral supplement was studied in 10 men during running (R) and control (C) conditions; the R was for 2 h at 60-65% of their maximal oxygen uptake. Subjects took the supplement with 200 ml of deionized water before the R or C (0-time). Blood was drawn before the Zn load and every 30 min for 3 h. By 2 h, plasma Zn concentrations had risen to values that were 151 +/- 7% and 149 +/- 5% of (0-time) R and C concentrations, respectively. Furthermore, the average rates of Zn uptake into the plasma did not differ between the R and C (4.4 vs 3.8 mumol.l-1.h-1) conditions. Finally, areas under the curve were not different (R: 13.2 +/- 1.8 mumol.l-1.3h-1; C: 11.5 +/- 1.5 mumol.l-1.3h-1). In summary, submaximal endurance running did not affect plasma Zn uptake and therefore absorption of Zn from a supplement taken just prior to exercise. The effect of chronic exercise on Zn absorption remains to be determined.

Survey of U.S. Army soldiers' knowledge, attitudes, and practices regarding personal protection measures to prevent arthropod-related diseases and nuisance bites.

This study examined U.S. Army soldiers' knowledge, attitudes, and practices regarding personal protection measures (PPMs) to prevent arthropod-related diseases and nuisance bites. Soldiers attending 1 of 13 U.S. Army training courses either completed a written questionnaire (N = 1,007) or participated in a group interview (N = 65). Respondents primarily used repellents to prevent nuisance insect bites (55%) rather than to prevent disease (38.7%). Less than one-third correctly identified the military-issue repellents to be used on skin (31.7%) or clothing (26.1%). More than half (57.6%) thought that commercial products were better than military-issue repellents, but most (74.2%) reported that they did not have enough or any information about the U.S. military's system of PPMs. Soldiers have poor knowledge of U.S. military doctrine regarding PPMs and still prefer to use commercial products. A focused strategy to ensure the appropriate use of PPMs by service members should be developed, implemented, and evaluated.

Seroepidemiologic survey for Coxiella burnetii among hospitalized US troops deployed to Iraq.

Q fever is a zoonotic illness which frequently has a non-specific clinical presentation. Cases among deployed US military personnel have been reported in increasing numbers indicating an emerging at-risk occupational group. Banked serum specimens were utilized to estimate seroprevalence and risk factors among military personnel deployed to Iraq. Coxiella burnetii antibody testing was performed and epidemiologic data were analysed from 909 servicemembers. The overall number who seroconverted to Q fever was 88 (10%). The most common ICD-9 code assigned to Q fever cases was fever not otherwise specified (NOS) (45%). A combat occupational specialty was a risk factor for Q fever seroconversion (OR = 1.8, 95% CI: 1.1-2.8) as well as receiving a primary diagnosis of fever NOS (OR = 2.6, 95% CI: 1.6-4.1). These findings indicate that Q fever is a significant infectious disease threat to military personnel deployed to Iraq. A heightened awareness among physicians is necessary to ensure prompt diagnosis and treatment.

Seroprevalence of Helicobacter pylori infections in a cohort of US Army recruits.

To study the prevalence and risk factors of Helicobacter pylori infection in healthy young adults, sera were collected from a nationwide sample of 404 females and 534 males (mean age, 20.2; range, 17-26 years) at induction into the US Army at Fort Jackson, South Carolina, during the fall of 1990. An enzyme-linked immunosorbent assay (PYLORI STAT, BioWhittaker, Inc., Walkersville, MD) was used to detect H. pylori-specific immunoglobulin G antibodies. Demographic data were obtained from a personnel database and by linking US census information to the subject's home address. The observed crude seropositivity rate was 26.3% (95% confidence interval 23.2-28.9). The direct sex-, race-, and geographic region-adjusted seropositivity rate was 20.8% (95% confidence interval 17.9-23.7). Seropositivity rates for blacks, Hispanics, and whites were 44%, 38%, and 14%, respectively, (chi 2, p < 0.001), and rates increased progressively from 24% in the age group 17-18 years to 43% in the age group 24-26 years (chi 2 for trend, p < 0.001). The age trends remained strong after controlling for race Median income was also an important predictive variable for seropositivity (chi 2, p < 0.0001). Sex, the percent urbanization, and population density of the home county were not significant predictors of seropositivity when age and race-ethnic group were controlled in a statistical model. The sharp increase in seroprevalence in this narrow age range suggests that the incidence rates are higher in young adults than previously reported.

Helicobacter pylori infection in Desert Storm troops.

To determine whether military personnel deployed outside the United States are at increased risk of Helicobacter pylori infection, we evaluated U.S. Army personnel who served in the Persian Gulf from August 1990 to April 1991. Of 204 subjects from whom paired predeployment and postdeployment serum specimens were obtained, 76 (37%) were seropositive for IgG antibody to H. pylori before deployment by an enzyme-linked immunosorbent assay. Of the 111 initially seronegative subjects evaluated before and after a 7.5-month deployment, five (4.5%) seroconverted. The calculated annual seroconversion rate was 7.3%. In a postdeployment questionnaire, 62% of soldiers reported an episode of diarrhea while deployed, but there was not an increased rate of diarrhea or upper gastrointestinal symptoms in soldiers who were infected before deployment or in those who seroconverted. These data suggest that the risk of H. pylori infection increases during long-term deployment and that acute infection is not distinguishable from other gastrointestinal illnesses encountered during deployment.

The effects of inadvertent exposure of mefloquine chemoprophylaxis on pregnancy outcomes and infants of US Army servicewomen.

During US military operations in Somalia, mefloquine, a drug for malaria chemoprophylaxis, was not approved for use in pregnant women. Some female soldiers inadvertently used mefloquine before becoming aware of their pregnancy. A registry was established to follow the outcomes of these pregnancies. Questionnaires were administered at the time the pregnancy was diagnosed, after termination or delivery, and at 1 year after birth. Seventy-two soldiers were eligible for the registry. There were 17 elective abortions, 12 spontaneous abortions, 1 molar pregnancy, and 23 live births. The outcome for 19 soldiers was unknown. An unexpected high rate of spontaneous abortions was observed. All infants were healthy at birth, with no major congenital malformations. One infant died at 4 months of viral pneumonitis. At 1 year of age, 13 infants were reported to be healthy, with normal cognitive and motor development. This study provides additional postmarketing data that mefloquine does not cause gross congenital malformations.

Evidence for a recent decrease in measles susceptibility among young American adults.

As part of an ongoing evaluation of US Army immunization policies, two serologic surveys were conducted at an army basic training center. Antibody status to measles, mumps, and rubella were determined by an ELISA in 969 soldiers in 1989 and 992 soldiers in 1990. Measles seronegativity rates, directly adjusted to the 15- to 24-year-old US population in 1980, decreased from 21.3% in 1989 to 12.5% in 1990 (P < .001). Decreases also were observed in mumps (16.2% to 14.7%) and rubella seronegativity rates (18.4% to 14.3%) from 1989 to 1990 but were not statistically significant. In subgroup analyses, significant decreases in measles seronegativity were observed in younger, white, male, and female cohorts. There is evidence that susceptibility among young adults had declined, although it remains unclear if this is due to increased immunization or exposure to natural disease.

Changes in lipoprotein profiles during intense military training.

The effects of intense military training on lipoprotein concentrations were monitored in a group of 44 Navy trainees. Dietary intakes and lipoprotein profiles were obtained before and after 5 weeks of physical conditioning and after 5 days of continuous, extremely intense physical and psychological stress. Body weight did not change significantly and dietary intakes were consistently high in saturated fat and cholesterol. After physical conditioning, serum total cholesterol and triglyceride concentrations were unchanged, while high-density lipoprotein (HDL) concentrations increased 31% (p less than 0.05). After 5 days of severe stress, total cholesterol and low-density lipoprotein concentrations decreased 17.2% and 30%, respectively (p less than 0.05), whereas HDL concentrations increased 12.1%. These data indicate that marked changes in lipoprotein profiles occur, not only with long-term physical conditioning, but also with strenuous training that lasts several days, despite high energy, fat, and cholesterol intakes.

Molecular and epidemiologic analysis of dengue virus isolates from Somalia.

Nucleotide sequence analysis was performed on 14 dengue virus isolates (13 dengue-2 viruses and 1 dengue-3 virus) recovered from febrile soldiers in Somalia in 1993. The dengue-2 viruses were most closely related to dengue-2 virus recovered in Somalia in 1984. However, differences in nucleotide sequence (0.35% to 1.35%) were evident among the 1993 isolates. These differences were closely associated with the geographic location of the infection as well as with different times of infection at the same location. Genetic difference between strains was not associated with differences in clinical features. Molecular analysis of dengue viruses is a useful adjunct to epidemiologic investigation of their distribution over distance and time.

Changes in nutrient intakes of conditioned men during a 5-day period of increased physical activity and other stresses.

Nutrient intakes and selected blood and urinary constituents of 16 Navy servicemen were obtained before and during a period of 113 hours of physical activity, sleep deprivation, and psychological stress, to document the dietary adaptation of physically conditioned men to an extended period of hard physical work and other stresses. Food intakes were monitored by 1-day diet records prior to and by direct observation during the period. The factorial method was used to calculate energy expenditure. Carbohydrates provided 45 and 43% of the total energy intake before and during the experiment. Protein intakes and intakes of all the vitamins and minerals studied exceeded the Recommended Dietary Allowances, both before and during the period. Total energy intake averaged 18.7 MJ.d-1 before and 24.4 MJ.d-1 during the experiment. Body weight increased significantly by 2.7 +/- 0.4 kg (mean +/- s.e.) during the experiment (p less than 0.0001). There was a significant correlation (r = 0.74; p less than 0.001) between the change in body weight and urinary sodium from before to after the experiment suggesting that increased dietary sodium may have contributed to the weight gain. A significant increase in plasma volume (11.9 +/- 3.2%; p less than 0.0003) provided further support that the observed weight gain was due to sodium intake rather than a positive energy balance. In conclusion, conditioned men increased food consumption adequately to meet increased energy demands.

45-year follow-up of hepatitis C virus infection in healthy young adults.

BACKGROUND: The sequelae during the first two decades after acute hepatitis C virus (HCV) infection have been well studied, but the outcome thereafter is unknown. OBJECTIVE: To conduct an extended study of the natural history of HCV infection by using archived serum specimens originally collected between 1948 and 1954. DESIGN: Retrospective cohort study. SETTING: A university, a Veterans Affairs medical center, and a medical follow-up agency that had access to the serum specimens and accompanying demographic and medical records. PARTICIPANTS: 8568 military recruits who were evaluated for group A streptococcal infection and acute rheumatic fever between 1948 and 1954. Blood samples were taken from the recruits and, after testing, were stored frozen for almost 45 years. MEASUREMENTS: The presence of antibodies to HCV was determined by enzyme-linked immunoassay, supplementary recombinant immunoblot assay, and polymerase chain reaction for HCV RNA. Morbidity and mortality were also assessed. RESULTS: Of 8568 persons, 17 (0.2%) had positive results on enzyme-linked immunosorbent assay and recombinant immunoblot assay. The rate was 1.8% among the African-American persons and 0.1% among the white persons in the total sample (relative risk, 25.9 [95% CI, 8.4 to 80.0]). During the 45-year follow-up, liver disease occurred in 2 of the 17 HCV-positive persons (11.8%) and 205 of the 8551 HCV-negative persons (2.4%) (ethnicity-adjusted relative risk, 3.56 [CI, 0.94 to 13.52]). Seven of the 17 HCV-positive persons (41 %) and 2226 of the 8551 HCV-negative persons (26%) had died by December 1996 (ethnicity-adjusted relative risk, 1.48 [CI, 0.8 to 2.6]). Of persons who were HCV-positive, 1 (5.9%) died of liver disease 42 years after the original phlebotomy, 5 (29%) died of non-liver-related disease a median of 37 years after the original phlebotomy, and 1 (5.9%) died of unknown causes. One hundred nineteen HCV-negative persons (1.4%) died of liver disease. CONCLUSIONS: The rate of HCV infection from 1948 to 1954 among a sample of military recruits parallels that among present-day military recruits and volunteer blood donors. During 45 years of follow-up, HCV-positive persons had low liver-related morbidity and mortality rates. This suggests that healthy HCV-positive persons may be at less risk for progressive liver disease than is currently thought.

Dengue fever in US military personnel in Haiti.

OBJECTIVE: To describe clinical manifestations and public health implications of an outbreak of dengue fever (DF) during Operation Uphold Democracy, Haiti, 1994. DESIGN: Consecutive sample. SETTING: Military combat support hospital, Port-au-Prince, Haiti. PATIENTS: A total of 101 US military personnel with acute febrile illnesses. INTERVENTIONS: A disease surveillance team collected clinical and epidemiologic data from US military clinics throughout Haiti. Febrile patients admitted to the combat support hospital were evaluated with standardized clinical and laboratory procedures. The surveillance team followed patients daily. MAIN OUTCOME MEASURES: Arbovirus isolation and specific antibody determination and symptoms and physical findings. RESULTS: Febrile illnesses accounted for 103 (25%) of the 406 combat support hospital admissions during the first 6 weeks of deployment. All patients with febrile illness recovered. A total of 30 patients had DF; no patient had evidence of infection with malaria. Dengue virus serotypes 1, 2, and 4 were isolated from 22 patients, and 8 patients developed IgM antibody to dengue virus. Patients with DF could not be distinguished from other febrile patients on clinical grounds alone. No arboviruses other than dengue were identified. CONCLUSIONS: Active surveillance, with clinical and laboratory evaluation directed by an epidemiologic team, led to the timely recognition of an outbreak of febrile illness among US troops in Haiti. Viral isolation and serological studies were essential in confirming DF. During the surveillance period, DF accounted for at least 30% of the febrile illnesses among hospitalized US troops. Dengue fever is a significant threat to military personnel and civilian travelers in Haiti and has the potential for introduction to and transmission in the United States.