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Biomedical subjects

H L Smith

Publications and source records attributed to H L Smith.

At least 37 records · Page 2Linked to original sources
PubMed2000

Tetracycline inhibits development of the infective-stage larvae of filarial nematodes in vitro.

In recent years, studies have linked tetracycline treatment of filaria-infected animals with reduced adult worm burdens and decreased levels of microfilaremia. These observations are believed to be attributable to clearance of Wolbachia, intracellular rickettsial-like organisms found within filarial tissues. Although maximal worm reductions were observed when treatment was initiated early in infection, it is not known whether tetracycline inhibits development of infective-stage larvae. To address this issue, we studied the effect of tetracycline on three different species of filarial nematodes, Brugia malayi, Brugia pahangi, and Dirofilaria immitis, in a serumfree in vitro system supporting molting to the fourth larval stage. Tetracycline was capable of inhibiting L3 to L4 molting within a dosage range similar to that reported for susceptible rickettsial organisms. However, Wolbachia DNA could still be detected in nematodes from tetracycline-treated cultures. In addition, three other antibiotics with anti-rickettsial and anti-chlamydial activity (chloramphenicol, erythromycin, and ciprofloxacin) failed to inhibit L3 to L4 molting. Although tetracycline is capable of completely blocking molting of infective-stage larvae, it remains possible that this effect is due to pharmacological activities unrelated to its anti-rickettsial functions.

Animals↗
PubMed2000

Development of a serum-free system for the in vitro cultivation of Brugia malayi infective-stage larvae.

Over the past several years, numerous attempts have been made to culture the infective-stage (L3) larvae of the human filarial parasite Brugia malayi in an in vitro system that promotes molting to the fourth larval stage (L4). Although there have been reports in the literature of successful L3 to L4 development in vitro, all of these systems have required serum supplementation. The complexity of serum as a culture supplement has made reproducibility of results and identification of specific factors necessary for L3 development problematic. We have developed a serum-free in vitro system consisting of RPMI 1640 supplemented with one of three fatty acids (arachidonic, linoleic, or linolenic) that supports consistent and reproducible molting to the fourth larval stage in the presence of a basidiomycetous yeast, Rhodotorula minuta. Coculture with this yeast, initially isolated as a culture contaminant, is required for successful molting. In serum-free cultures lacking R. minuta, L3 larvae survive for upward of 2 weeks, but do not molt successfully. The L4 larvae generated in cultures containing R. minuta are well formed, as seen by light and electron microscopy, and are capable of further development upon transfer to a permissive host. This culture system is inexpensive and easily reproducible, thus making it a useful tool for studying the requirements for the development of B. malayi L3.

Animals↗
PubMed2000

The poverty of information systems management in home health agencies: implications for survivability.

Home health agencies are increasingly being challenged to cope with economic, financial and clinical pressures. This study examines the extent to which home health agencies have cultivated their information systems as an aid for managing performance and external forces. Colorado and New Mexico home health agencies participated in the research project. The findings indicate that only modest investments have been made by respondents in their information systems. The typical respondent reports a personal computer-based system which addresses some financial reporting data, but which does not emphasize care delivery or contextual factors. The implications of these findings for the survivability of home health agencies are discussed.

Colorado↗
PubMed2000

Husbands' versus wives' fertility goals and use of contraception: the influence of gender context in five Asian countries.

Using data from Pakistan, India, Malaysia, Thailand, and the Philippines, we explore how gender context influences (1) husband-wife concordance in the demand for children and (2) the impact of each spouse's fertility preferences on contraceptive use. We also explore whether the husband's pronatalism can explain the wife's unmet need for contraception. The results suggest that gender context has little net effect on couples' concordance, but influences the relative weight of husbands' and wives' preferences in determining contraceptive use. Analysis of women's unmet need for contraception suggests that the husbands' pronatalism contributes to wives' unmet need, but only to a relatively small degree, especially in settings where unmet need is high. This is the case because the proportion of couples with differing fertility goals is small in most communities.

Asia↗
PubMed1999

Benchmarking patient relations within ambulatory care: lessons from a high-risk pregnancy program.

Ambulatory care providers are being challenged to deliver high-quality care at low cost with easy access. Patient satisfaction with services hinges on the ability of providers to meet these often elusive benchmarks. This article focuses on the barriers to benchmarking patient relations in ambulatory care organizations and strategies for improving patient relations through internal benchmarking that encourages service innovation and performance emphasis. A case study of programmatic benchmarking in the Lovelace Health System is used to illustrate how patient relations can benefit from establishing internal performance thresholds that guide service delivery. Examples from Lovelace's High Risk Pregnancy Program demonstrate the value of benchmarking efforts. The implications for patient relations benchmarking in other ambulatory care settings are discussed.

Ambulatory Care↗
PubMed1999

The poverty of information systems management in home health agencies: implications for survivability.

Home health agencies are increasingly being challenged to cope with economic, financial and clinical pressures. This study examines the extent to which home health agencies have cultivated their information systems as an aid for managing performance and external forces. Colorado and New Mexico home health agencies participated in the research project. The findings indicate that only modest investments have been made by respondents in their information systems. The typical respondent reports a personal computer-based system which addresses some financial reporting data, but which does not emphasize care delivery or contextual factors. The implications of these findings for the survivability of home health agencies are discussed.

Computer Systems↗
PubMed1997

Using existing health care systems to respond to the AIDS epidemic: research and recommendations for Chile.

Chile is a country with a relatively low prevalence of HIV infection, where successful prevention has the potential to change the future course of the epidemic. A controversial national prevention strategy based upon public education has emerged in response to characterizations of the epidemic as well-dispersed with a growing involvement of heterosexuals. This characterization is not consistent with the observed facts. There is a comparatively well-organized health care system in Santiago that is doing a good job of detecting HIV infection and already has in place the elements of a targeted intervention scheme. Chile should place priority on the use of the existing health care infrastructure for implementing both the traditional public health interventions for sexually transmitted diseases (contact tracing and partner notification) and the AIDS-necessitated strategy of focused counseling and education.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Acceptance, efficacy, and side effects of Norplant implants in four counties in north China.

This report attempts to present a comprehensive analysis of the acceptability, side effects, and efficacy of Norplant as used in rural areas, based on a field experiment conducted in four counties in Hebei and Shandong Provinces, China. The initial acceptance of Norplant was relatively high but waned after the first year in three of the four counties. Compared with clinical trials, the current study shows a lower prevalence but similar patterns of side effects. The pregnancy rate during the first two years of use is similar to that found in large-scale clinical trials conducted in China, but discontinuation due to other reasons is lower. A three-level logistic regression analysis shows significant variation in the probability of discontinuation due to side effects across counties. It also indicates an increase in the conditional probability of discontinuation with the duration of use. Whereas introducing Norplant and achieving a very low failure rate and high continuation rate in rural areas is feasible under diverse socioeconomic conditions, the results vary significantly across different areas. Particular attention should be paid to the local factors that may affect results.

Adult↗
PubMed1996

The role of functional status in predicting inpatient mortality with AIDS: a comparison with current predictors.

To assess the independent prognostic role of functional status, as reflected by a measure of an inpatient's global requirement for nursing assistance with basic activities of daily living (Global ADL), we compared Global ADL with three validated AIDS mortality predictors: the Clinical AIDS Prognostic Staging (CAPS); the Severity Classification System for AIDS Hospitalization--version 2 (SCAH-2); and CD4 cell count. Our study sample consisted of 1392 patients with AIDS and a hospital stay of 3 or more days at one of 20 hospitals in 11 U.S. cities with high AIDS incidence. Data were collected from September 1990 through December 1991. Two percent of patients refused participation, and 26% were eliminated due to incomplete data collection, leaving an analytic sample of 1003 patients. Only 30% of patients had a CD4 count measured at any time during hospitalization. Cox regression was used to measure the hazard of inpatient mortality adjusted for length of stay. Overall mortality was 12%. Mortality rates for patients in Global ADL stages I-IV were 3%, 8%, 19%, and 51%, respectively (p < 0.0001). Global ADL more effectively discriminated mortality than CAPS (p < 0.001), SCAH-2 (p < 0.001), or CD4 count (p < 0.001). Global ADL also added independent information in analyses adjusted for both CAPS and SCAH-2: a single stage increase of Global ADL demonstrated a 1.9-fold increased hazard of death (CI: 1.6, 2.3). SCAH-2, assigned at discharge, was not strongly correlated with admission predictors (Global ADL: r = 0.17; CI: 0.11, 0.23 or CAPS: r = 0.03, CI: 0.02, 0.17). We conclude that Global ADL, alone or in tandem with other severity systems, provides an excellent severity adjustment for inpatient mortality with AIDS. Finally, CD4 cell counts were not routinely available and were not as predictive as Global ADL in the patients for whom both were available.

Acquired Immunodeficiency Syndrome↗
PubMed1996

The effect on the heart of hypoxaemia in patients with severe coronary artery disease.

The aim of the study was to examine the effect of spontaneous nocturnal hypoxaemia on myocardial ischaemia in patients with severe coronary artery disease. This was a prospective study of continuously measured oxygen saturation and ECG overnight in patients prior to coronary artery bypass graft surgery. Fifteen patients with angiographically proved coronary artery disease were studied between October 1992 and September 1993. All patients had episodes of hypoxaemia with oxygen saturation < 94% and eight of the 15 patients had episodes where oxygen saturation < 85%. An episode was defined as a period of hypoxaemia not less than 2.5 min in duration, the longest total duration of hypoxaemia in one patient being 355 min. Twelve of the 15 patients showed a drop in ST segment of 1 mm or more lasting from 5-700 min. The hypoxaemic and ischaemic episodes apparently occurred at random. No causal relationship could be shown between hypoxaemia and ischaemia.

Adult↗
PubMed1996

A decomposition of trends in the nonmarital fertility ratios of blacks and whites in the United States, 1960-1992.

We use a method of standardization and decomposition developed by Das Gupta to update Smith and Cutright's analysis of demographic factors responsible for increases in the nonmarital fertility ratio (illegitimacy ratio) among blacks and whites in the United States. We create standardized rates for each year between 1960 and 1992, and consistent, exhaustive decompositions of the nonmarital fertility ratio for any interval during this period in terms of four components: (1) the age distribution of women of reproductive age, (2) the proportion of women unmarried at each age, (3) the age-specific birth rates of married women, and (4) the age-specific birth rates of unmarried women. Nonmarital fertility ratios are much higher among blacks than among whites, but both increased monotonically from 1960 to 1992. During the last 10 years, each increased by nearly 10 percentage points. Increases in the proportion of women not married, at all ages, account for the preponderance of the increase in black nonmarital fertility ratios. Increasing rates of unmarried childbearing, however, have played a role during the most recent decade (1983-1992). For whites, from 1960 until 1975, declines in marital fertility were most important in producing increases in the proportion of children born out of wedlock. Since then, these proportions have increased primarily because of increases in unmarried women's birth rates, and secondarily because of declines in the proportion of women who are married. These trends are consistent with arguments that emphasize declining economic incentives to marry and reduced access to, and acceptability of, abortion.

Adolescent↗
PubMed1995

Vestibulo-ocular reflex (VOR) biases in normal subjects and patients with compensated vestibular loss.

The properties of the vestibulo-ocular reflex (VOR) were examined during sinusoidal passive head rotation in the dark at 1/6 Hz, in 9 normal subjects and 14 unilateral vestibular patients. Rotation speeds ranged from 90 to 180 degrees/s. The bias (offset of slow-phase velocity from zero) and gain in the VOR were estimated by using a polynomial (cubic) fit between head and slow-phase eye velocity, thereby allowing for possible non-linearities in the reflex. The gain in the VOR in this context refers to the linear components of the fit, and so predicts sensitivity only at low head velocities. The aim of the study was to verify previous theoretical predictions that VOR bias could vary with the rotation parameters, that this bias could be used to detect the side of a vestibular lesion even at low frequency rotation, and make non-linearities more obvious. Confirming these predictions, the VOR bias in a given test is never equal to any spontaneous nystagmus, even if present before rotation. The range of values for the gain in the VOR (as defined above) in normals and compensated unilateral vestibular patients overlap, so that they cannot be statistically separated into two response sets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Comparison of linear vs. non-linear methods for analysing the vestibulo-ocular reflex (VOR).

The vestibulo-ocular reflex (VOR) is traditionally evaluated by the gain (sensitivity) and offset (bias) of nystagmus slow phases during sinusoidal, passive, head rotation in the dark. The analysis methods used are typically only truly applicable to linear systems, but are widely used despite the fact that the VOR has been known to be non-linear since the 19th century. We show here that the parameters obtained by linear methods, with data derived from a non-linear system, can be very noisy and unreliable. The questions are: under what conditions can linear approximations be tolerated, or justified, and can an analysis approach be devised which inherently tolerates non-linearities? Using both simulated and experimental data, it is found that assuming linear analysis methods can produce variable VOR gains and erroneous estimates of the VOR bias. changing with the selected oscillation protocol. Examples of' parameter distortions in bias and VOR gain are first given using simulated data relating slow phase eye velocity to head velocity, at different peak velocities. The relevance of these distortions is then illustrated with selected examples from a database of recordings on normals and unilateral vestibular patients, during rotations in the dark 1/6 Hz and maximum speeds of 90 to 180 degrees/s. More consistent estimates of the gain and bias can be found by properly correcting for phase differences between head and eve velocity, and allowing for non-linear reflex properties. Special indices are suggested to decide whether a particular subject's VOR should be considered non-linear, in order to select the appropriate representation in each case, before estimating VOR characteristics. Selecting the appropriate model (linear or non-linear) will contribute to a better unmasking of parametric trends in the VOR, when comparing normal vs. acute-lesioned subjects, or acute vs, compensated patients. These results have many implications for the design of clinical vestibular protocols and in the evaluation of patient functional deficits.

Computer Simulation↗