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Biomedical subjects

R N Miller

Publications and source records attributed to R N Miller.

At least 37 records · Page 2Linked to original sources
PubMed1990

Human immunodeficiency virus seropositivity among members of the active duty US Army 1985-89.

Between October 1985 and June 1989, most active duty US Army soldiers were screened for human immunodeficiency virus (HIV) antibody. Of 648,032 screened soldiers in this analysis, 1,588 were HIV-antibody positive. In a multivariate analysis, correlates of positivity included: age [Adjusted Odds Ratios (ref less than 20 years) = 20-24 years, 3.7; 25-29, 9.3; 30-34, 15.7; greater than or equal to 35, 15.9]; being male, [4.2]; being Black or Hispanic (vs white) [3.7 and 3.0, respectively]; being single (vs married) [3.8]; assignment to an HIV endemic location [1.7], and having a medical occupation [2.7, 2.7, and 2.6 for negligible, low, and high blood exposure professions, respectively]. Seropositivity rate ratios for medical vs non-medical personnel were 0.7 [95% CI = 0.4, 1.4] for females and 2.9 [95% CI = 2.5, 3.3] for males. For male medical personnel, being single (vs married) correlated strongly with antibody positivity [prevalence ratio = 3.4, 95% CI = 2.6, 4.6]. Excess HIV risk among medical personnel appeared largely attributable to factors other than occupational exposures.

Adult↗
PubMed1990

Tracking the spread of the HIV infection epidemic among young adults in the United States: results of the first four years of screening among civilian applicants for U.S. military service.

Because the period from infection to clinically apparent disease is long, variable, and changing as new therapies are developed and applied, AIDS data are inadequate for tracking current values of critical parameters of HIV infection epidemics: prevalence of infection, rate of acquisition of new infections (incidence rate), and direction and rate of change of infection incidence over time (acceleration). These "vital signs" of infection epidemics can be tracked using serial cross-sectional seroprevalence data, however. From October 1985 through September 1989, more than 2.3 million applicants for U.S. military service were screened for antibody to HIV. The overall seroprevalence was 1.31 per 1,000 (3,014/2,300,675). Seroprevalences were highest near urban centers of the AIDS epidemic and were independently associated with age, race/ethnicity, and gender. Based on age seroprevalence trends, it was crudely estimated that at least one of 2,000 young men and one of 7,000 young women are infected with HIV annually in the U.S. Infection incidence rates, estimated from age and temporal trends, were estimated to be highest among black males (1.40/1,000/year) and lowest among white females (0.03/1,000/year). Poisson regression analysis of seroprevalence trends suggested that infection incidence rates accelerated among black females during the first 3 years of screening. Since selection factors undoubtedly changed over the period, estimates based on these data probably underestimate actual values in the general population, particularly near urban AIDS epicenters. Nonetheless, even crude estimates of these critical values, particularly among adolescents and young adults, are useful to guide policy development, to allocate resources, and to monitor program effects.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Direct measurement of human immunodeficiency virus seroconversions in a serially tested population of young adults in the United States Army, October 1985 to October 1987. Walter Reed Retrovirus Research Group.

Direct measurement of the incidence of infection with the human immunodeficiency virus (HIV)--the rate of new HIV infection--is vital if we are to understand better the dynamics of the current epidemic of HIV infection. Because soldiers are periodically and routinely screened for antibody to HIV, it is possible to measure the incidence of HIV infection directly in this large, demographically well-characterized population of young adults. To determine the incidence of HIV infection in this population, we examined test results reported by the U.S. Army's routine antibody-screening programs. During the first two years of the screening programs, the observed incidence of HIV infection was approximately 0.77 per 1000 persons per year. This rate was higher than expected on the basis of previously published estimates of seroprevalence in the Army (approximately 1.50 per 1000). On the basis of this annual incidence, and assuming it to be stable, we estimate that approximately 600 soldiers will become infected with HIV each year. The observed rate in the Army may be lower than the incidence of HIV infection in the corresponding demographic groups within the general U.S. population.

AIDS Serodiagnosis↗
PubMed1989

An outbreak of hookworm infection associated with military operations in Grenada.

During 1983, a multinational military intervention took place on Grenada. After deployment, troops from several U.S. Army units noted signs and symptoms consistent with soil-transmitted helminthic infection. Of 684 soldiers screened five to seven weeks post-deployment, over 20% reported abdominal pain and/or diarrhea during or after the action. Eosinophilia of at least 10% was observed in 119 (22.5%) of 529 soldiers evaluated further; eosinophilia of 5-9% was documented in another 126 (23.8%) of the 529 soldiers. Stool examinations confirmed hookworm infection in 35 soldiers. One case of strongyloidiasis was also documented. Infection was attributed to ground exposure near homes with compromised sanitation. Units that joined the operation after the initial assault phase were at low risk of hookworm infection.

Disease Outbreaks↗
PubMed1989

Evidence for spread of the human immunodeficiency virus epidemic into low prevalence areas of the United States.

Reports of an increased proportion of AIDS cases occurring in small and medium-sized cities suggest that the HIV epidemic may be spreading into locations that were previously characterized by their low HIV antibody prevalences. Studying the question of the geographic spread of the HIV infection epidemic (rather than the AIDS epidemic) has been difficult largely because most serial seroprevalence data have been gathered from cohorts of high risk individuals (e.g., homosexual/bisexual cohorts) in New York City, San Francisco, and other geographically circumscribed areas. The U.S. military applicant HIV screening data were used in the current report to examine rates and 24 month temporal trends in geographic areas characterized by their HIV endemicities. The data examined concern the seven most populous states and four hyperendemic metropolitan areas located within those states (New York City, Miami, Houston, and San Francisco). In the nonepidemic regions, seroprevalence rates increased among black and white applicants. In the four epidemic urban areas, only young black applicants had higher HIV seroprevalence rates during the second 12 month period. Six of the seven nonepidemic regions had positive HIV seroprevalence trends, and these trends were significant in Florida, California, Texas, Illinois, and Ohio. The increases in these regions were greater for young blacks (30% excess for year 2 vs. year 1) compared to young whites (12% excess for year 2 vs. year 1). These data provide evidence of birth year specific increases in seroprevalence over time occurring in presumed low HIV prevalence areas. These increases cannot be due to, but are observed in spite of, biases associated with increasing self-selection over time.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Building-associated risk of febrile acute respiratory diseases in Army trainees.

Airborne transmission of infectious agents and associations of indoor air pollutants with respiratory illnesses are well documented. We hypothesized that energy conservation measures that tighten buildings also increase risks of respiratory infection among building occupants. At four Army training centers during a 47-month period, incidence rates of febrile acute respiratory disease were compared between basic trainees in modern (energy-efficient design and construction) and old barracks. Rates of febrile acute respiratory disease were significantly higher among trainees in modern barracks (adjusted relative risk estimate, 1.51; 95% confidence interval, 1.46 to 1.56), and relative risks were consistent at the four centers. These results support the hypothesis that tight buildings with closed ventilation systems significantly increase risks of respiratory-transmitted infection among congregated, immunologically susceptible occupants.

Adenovirus Infections, Human↗
PubMed1986

Occupational and geographic risk factors for hepatitis B among US Army enlisted personnel during 1980.

Hepatitis B hospitalization rates for US Army enlisted personnel were determined by occupation and geographic area for 1980. The only group in the US Army currently recommended to receive hepatitis B vaccine is medical personnel regularly exposed to blood. Other groups of Army personnel, specifically those working in areas of high hepatitis B endemicity, have been thought to be at higher risk. Therefore, this work was undertaken to document hospitalization rates for all personnel using occupational blood exposure criteria as well as geographic area of assignment as risk factors for hepatitis B. The hospitalization rates underestimate true rates of hepatitis B incidence by a wide margin, and therefore were not used to calculate specific costs and specific benefits for a new vaccination strategy. In spite of this limitation, these data were useful for calculating relative risk, attributable risk, and amount of vaccine preventable disease. The risk of hospitalization for blood-exposed employees was consistently higher than that for non-blood-exposed personnel. The magnitude of the relative risk for blood exposure may be as high as 3.8 times or as low as 1.2 times, depending on which occupational comparison group is used. The relative risk of hospitalization in South Korea vs. the United States was 3.1 (p less than 0.0001), that for Europe vs. the United States, 2.1 (p less than 0.0001). Of all occupational and geographic risk comparisons, assignment to South Korea carried the highest attributable risk: 225 per 100,000. The amount of vaccine preventable disease in personnel assigned to South Korea was similar to that in occupationally blood-exposed employees (5.5 vs. 5.2 hospitalized cases per 1,000 vaccinees) after prorating exposure to risk based on average number of days of exposure to risk over three years. These data support the argument that geographic factors are as important as occupational blood exposure in defining risk of hepatitis B hospitalization among the US Army enlisted personnel.

Blood↗
PubMed1985

Rapid serodiagnosis of leptospirosis using the IgM-specific Dot-ELISA: comparison with the microscopic agglutination test.

The dot enzyme-linked immunosorbent assay (Dot-ELISA) was compared to the microscopic agglutination test (MA test) for the diagnosis of human leptospirosis. Of 177 sera from 68 soldiers who trained in the Republic of Panama, 102 sera were positive in the MA test and 93 of these sera were positive in the IgM-specific Dot-ELISA. Incidence of infection was 50 of 68 patients with the MA test and 48 of 68 in the IgM Dot-ELISA. Five MA test-positive sera were reactive only in the IgG-specific Dot-ELISA, suggesting previous exposure. All 21 infecting serovars of Leptospira interrogans, as determined by positive reactions in the MA test or culture of blood and urine specimens, were reactive in the Dot-ELISA. Of 75 sera negative in the MA test, 61 were nonreactive in the Dot-ELISA. However, 9 of these 14 Dot-ELISA-positive/MA test-negative sera were acute samples from patients whose later sera were MA test-positive. Positive reactions in the IgM Dot-ELISA occurred in 2 of 30 control, 4 of 10 Lyme disease, 1 of 11 relapsing fever, and 1 of 8 yaws sera; 10 syphilis patient sera were nonreactive. The IgM-specific Dot-ELISA appears to be sensitive and specific for the serodiagnosis of acute leptospirosis. In addition, this rapid test is inexpensive, simple to perform, utilizes minute volumes of killed leptospiral antigen and is easily adaptable to field use.

Agglutination Tests↗
PubMed1984

Failure to achieve predicted antibody responses with intradermal and intramuscular human diploid cell rabies vaccine.

In a study to compare the immunogenicity of human diploid cell rabies vaccine (HDCV) given by intramuscular or automatic intradermal jet injection, neither method of administration resulted in antibody levels predicted by previous studies. 49 days after starting a series of three 0.1 ml doses of HDCV given intradermally, 85 volunteers had a geometric mean titre (GMT) of neutralising antibody to rabies of 1:170. 9 concurrent control subjects who received 1.0 ml doses of vaccine intramuscularly had a GMT of only 1:269. Although standard potency testing did not demonstrate that the vaccine used was subpotent , these results strongly suggest that the immunogenicity of HDCV is substantially less than previously reported.

Antibodies, Viral↗
PubMed1984

An efficacy trial of doxycycline chemoprophylaxis against leptospirosis.

Because leptospirosis has been an important cause of morbidity in U.S. soldiers training in the Republic of Panama, we conducted a randomized, double-blind, placebo-controlled field trial during the fall of 1982 to determine whether doxycycline was an effective chemoprophylactic agent against this infection. Doxycycline (200 mg) or placebo was administered orally on a weekly basis and at the completion of training to 940 volunteers from two U.S. Army units deployed in Panama for approximately three weeks of jungle training. Twenty cases of leptospirosis occurred in the placebo group (an attack rate of 4.2 per cent), as compared with only one case in the doxycycline group (attack rate, 0.2 per cent, P less than 0.001), yielding an efficacy of 95.0 per cent. This study demonstrated the value of doxycycline as a prophylactic drug against leptospirosis.

Clinical Trials as Topic↗
PubMed1982

Study on the effectiveness of remote mental healing.

A study which involved eight healers and ninety-six patients was conducted to determine the effectiveness of remote mental healing. The test subjects were hypertension patients between the ages of sixteen and sixty. Neither the doctor nor the patients knew who received the mental healing treatments. Normal medical treatment was continued in all cases. Improvement was judged by changes in the diastolic blood pressure, systolic blood pressure, heart beat rate, and weight. The statistical analysis showed a significant improvement in the systolic blood pressure of the healer-treated group compared with the change in the control group. There were no significant differences in the changes of diastolic blood pressure, pulse, and weight of the two groups. Four of the healers had a 92.3 per cent improvement ratio in their total group of patients compared with a 73.7 per cent improvement for the control group. The general healing treatment used by the healers involved (a) a relaxation step, (b) attunement with a Higher Power or Infinite Being, (c) a visualization and/or affirmation of the patient being in a state of perfect health, and (d) expression of thanks to God or to the Source of all power and energy.

Blood Pressure↗
PubMed1982

Etiology of viral hepatitis in American soldiers.

To define better which types of hepatitis are prevalent among American soldiers, the authors studied 413 separate episodes of acute viral hepatitis among 412 soldiers admitted to US Army hospitals during 1978-1979. Most soldiers (68.8%) had acute hepatitis B (estimated annual hospitalization rate: 5.41/1000 soldiers in West Germany, 2.51/1000 in South Korea, less than 1/1000 in the United States). Subtype ayw was predominant in Germany, whereas adr was predominant in South Korea. Hepatitis B was more often associated with contact history or parenteral use of drugs in West Germany than in South Korea (p less than 0.001). Non-A, non-B hepatitis accounted for 27% of cases in West Germany (2.16/1000), but only 3% in South Korea (0.11/1000); hepatitis A only 15% in South Korea (0.48/1000) and 1% in West Germany (0.08/1000). These findings indicate that hepatitis B is the most prevalent form of viral hepatitis among US soldiers worldwide but also suggest substantial differences in the epidemiology of this infection in South Korea and West Germany. Such data will be useful in developing hepatitis B immunization policy within the military.

Adult↗
PubMed1981

The dependence of impulse propagation speed on firing frequency, dispersion, for the Hodgkin-Huxley model.

Propagation speed of an impulse is influenced by previous activity. A pulse following its predecessor too closely may travel more slowly than a solitary pulse. In contrast, for some range of interspike intervals, a pulse may travel faster than normal because of a possible superexcitable phase of its predecessor's wake. Thus, in general, pulse speeds and interspike intervals will not remain constant during propagation. We consider these issues for the Hodgkin-Huxley cable equations. First, the relation between speed and frequency or interspike interval, the dispersion relation, is computed for particular solutions, steadily propagating periodic wave trains. For each frequency, omega, below some maximum frequency, omega max, we find two such solutions, one fast and one slow. The latter are likely unstable as a computational example illustrates. The solitary pulse is obtained in the limit as omega tends to zero. At high frequency, speed drops significantly below the solitary pulse speed; for 6.3 degrees C, the drop at omega max is greater than 60%. For an intermediate range of frequencies, supernormal speeds are found and these are correlated with oscillatory swings in sub- and superexcitability in the return to rest of an impulse. Qualitative consequences of the dispersion relation are illustrated with several different computed pulse train responses of the full cable equations for repetitively applied current pulses. Moreover, changes in pulse speed and interspike interval during propagation are predicted quantitatively by a simple kinematic approximation which applies the dispersion relation, instantaneously, to individual pulses. One example shows how interspike time intervals can be distorted during propagation from a ratio of 2:1 at input to 6:5 at a distance of 6.5 cm.

Animals↗
PubMed1979

A simple model of delay, block and one way conduction in Purkinje fibers.

A simple qualitative model of the cardiac Purkinje fiber is introduced for the purpose of numerical simulation of experiments on conduction of the cardiac impulse. Well known approximation techniques are used to illustrate the behavior of the model membrane in the cases of space clamp and propagation of traveling pulses in a uniform infinite fiber. The results of the numerical simulations are then presented, and shown to be comparable to experiment.

Action Potentials↗