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Biomedical subjects

E Drucker

Publications and source records attributed to E Drucker.

At least 19 recordsLinked to original sources
PubMed2001

Serial human passage of simian immunodeficiency virus by unsterile injections and the emergence of epidemic human immunodeficiency virus in Africa.

There is compelling evidence that both human immunodeficiency virus (HIV) types emerged from two dissimilar simian immunodeficiency viruses (SIVs) in separate geographical regions of Africa. Each of the two HIVs has its own simian progenitor and specific genetic precursor, and all of the primates that carry these SIVs have been in close contact with humans for thousands of years without the emergence of epidemic HIV. To date no plausible mechanism has been identified to account for the sudden emergence in the mid-20th century of these epidemic HIVs. In this study we examine the conditions needed for SIV to complete the genetic transition from individual human SIV infections to epidemic HIV in humans. The genetic distance from SIV to HIV and the mutational activity needed to achieve this degree of adaptation to human hosts is placed within a mathematical model to estimate the probabilities of SIV completing this transition within a single SIV-infected human host. We found that the emergence of even one epidemic HIV strain, following a single human exposure to SIV, was very unlikely. And the probability of four or more such transitions (i.e. HIV-1 groups M, O and HIV-2 subtypes A and B) occurring in a brief period is vanishingly small. We conclude that SIV cannot become a zoonosis, but requires adaptive mutations to become HIV. Some modern event must have aided in the transition of SIV to HIV. Our research indicates that serial passage of partially adapted SIV between humans could produce the series of cumulative mutations sufficient for the emergence of epidemic HIV strains. We examined the rapid growth of unsterile injections in Africa beginning in the 1950s as a biologically plausible event capable of greatly increasing serial human passage of SIV and generating HIV by a series of multiple genetic transitions. We conclude that increased unsterile injecting in Africa during the period 1950-1970 provided the agent for SIV human infections to emerge as epidemic HIV in the modern era.

Africa↗
PubMed2000

Office-based methadone prescribing: acceptance by inner-city practitioners in New York.

In the US, methadone maintenance is restricted by federal and state regulations to large specialized clinics that serve fewer than 20% of the heroin-dependent population. In Europe, Canada, and Australia, primary health care providers already are utilized widely as methadone prescribers. In preparation for a limited study of office-based methadone treatment in New York City, 71 providers from 11 sites were surveyed about their willingness to prescribe methadone in their office-based practices. Of the 71, 85% had methadone-maintained patients who came to their practice for other care. One-third felt knowledgeable enough to prescribe methadone, and 66% said they would if given proper training and support (88% among AIDS care providers). Half expressed concern that they might be unable to meet the multiple needs of these patients. With additional training and ancillary support, the 47 providers willing to become methadone providers could serve, at 10-20 patients each, 470-940 patients, a population the size of 3-5 average methadone clinics.

Attitude of Health Personnel↗
PubMed1998

Housing issues of persons with AIDS.

The housing status of persons with HIV/AIDS is a central issue in their care and prognosis. We conducted eight focus groups to explore the housing needs of special populations of persons with HIV/AIDS in New York State; these populations included substance users, ex-offenders, persons with documented histories of homelessness, and rural dwellers/migrant workers. For the focus groups, 52 participants were recruited from the clientele of health and social service agencies. A major theme was the potent effect that housing situations had on participants' health. Participants frequently attributed lowered T-cell counts and increased lethargy to the stress associated with governmental rules and paperwork. Lack of money, inadequacy of entitlements, and high costs of housing were the major barriers to securing stable and appropriate housing. Furthermore, participants experienced housing discrimination based on HIV status and experience with the criminal justice system or drugs.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Mediastinal lymphadenopathy and hazy mediastinal fat: new CT findings of congestive heart failure.

OBJECTIVE: We describe two new CT findings of congestive heart failure (CHF): enlarged mediastinal lymph nodes and hazy heterogeneous mediastinal fat. MATERIALS AND METHODS: Forty-six patients were retrospectively identified who had major and minor clinical signs of congestive heart failure and had undergone chest CT during their symptomatic period. Two radiologists reviewed the CT studies and by consensus documented the presence or absence of imaging findings of CHF, including interstitial abnormalities, vascular redistribution, axial thickening, pleural effusions, cardiac enlargement, and mediastinal abnormalities. RESULTS: Smooth septal thickening, bilateral pleural effusions, vascular redistribution, and cardiac enlargement were the most common CT findings in patients with CHF. Enlarged mediastinal lymph nodes and hazy mediastinal fat were seen in 55% and 33% of cases, respectively. In a cohort of 17 patients with elevated pressures in the pulmonary capillary wedge documented within 24 hr of CT, CT scans revealed lymphadenopathy in 14 patients (82%) and inhomogeneous fat in 10 patients (59%). CONCLUSION: Enlarged mediastinal lymph nodes and hazy mediastinal fat occur in patients with CHF and are revealed by CT. Lymphadenopathy in patients with CHF does not necessarily indicate malignancy or an infectious process.

Adipose Tissue↗
PubMed1998

Cost-effective screening for cerebral aneurysms.

The advent of accurate, noninvasive angiography has raised hopes that premorbid screening for cerebral aneurysm will soon be possible. This article discusses the medical and economic issues which will determine the appropriate conditions for, and cost-effectiveness of, large-scale aneurysm screening.

Cerebral Angiography↗
PubMed1997

An opportunity lost: HIV infections associated with lack of a national needle-exchange programme in the USA.

BACKGROUND: Our aim was to estimate the number of HIV infections that could have been prevented had needle-exchange programmes been implemented during the early stages of the AIDS epidemic in the USA. We also estimated the cost to the US health-care system to treat these preventable HIV infections. METHODS: The formula we used to calculate the annual number of preventable HIV infections accounted for the effectiveness and level of use of needle-exchange programmes, as well as sexual transmission to injection drug users (IDUs) and secondary transmission to their sexual partners and children. Data for the model were obtained from epidemiological and mathematical studies in peer-reviewed published research, government reports, and consultations with experts. Using data from Australia as a model, we calculated the number of HIV infections that could have been prevented by a national needle-exchange programme in the USA between 1987 and 1995. Cost calculations were based on the current US government estimate of the discounted lifetime cost of treating an HIV infection (US $55640). FINDINGS: Our conservative calculation of the number of HIV infections that could have been prevented ranged from 4394 (15% incidence reduction due to needle exchanges) to 9666 (33% incidence reduction). The cost to the US health-care system of treating these preventable HIV infections is between US $244 million and US $538 million, respectively. If current US policies are not changed, we estimate that an additional 5150-11329 preventable HIV infections could occur by the year 2000. INTERPRETATION: The failure of the federal government in the USA to implement a national needle-exchange programme, despite six government-funded reports in support of needle exchanges, may have led to HIV infection among thousands of IDUs, their sexual partners, and their children. Revoking the US government ban on funding for needle-exchange programmes and accelerating the growth of such programmes in the USA are urgent public-health priorities.

Cost of Illness↗
PubMed1997

Kinematic and electromyographic analysis of steady pectoral fin swimming in the surfperches

The musculoskeletal mechanism of pectoral fin propulsion was investigated in representatives of the two subfamilies of the Embiotocidae (surfperches). Kinematic and electromyographic records of steady swimming by the open-water cruiser Amphistichus rhodoterus and the benthic maneuverer Embiotoca lateralis were compared at 80 % of the species' respective pectoral­caudal gait transition speeds. Synchronized records of fin movement and the intensity of pectoral muscle activity allowed previous hypotheses of muscle function, based on anatomical lines of action, to be tested. Divisions of the pectoral musculature inserting on the central and trailing- edge fin rays serve simple functions of abduction and adduction. Muscles controlling the fin's leading edge, by contrast, play more complex roles during the fin stroke, including deceleration of the fin at the downstroke­upstroke transition and rotation of the adducted fin during the non-propulsive period between fin beats. In spite of their phylogenetic and ecological divergence, the surfperches exhibit a number of mechanistic similarities which probably characterize the family. The timings of kinematic events and the maximal excursions of the fin tip, as well as the temporal order of muscle activation and the time to peak activity, are largely conserved. The predominant dorsoventral component of fin movement during the stride is consistent with a lift-based mechanism of propulsion. E. lateralis exhibits a greater anteroposterior range of motion and a more continuous period of fine motor control of the fin than A. rhodoterus, differences which may correspond to the species' respective capacities for maneuvering. Mechanistic variation in the family is associated with rather minor structural differences (in fin shape and fin base orientation). Owing to the similar functional demands placed on the pectoral fins of many fishes, it is probable that the mechanistic details of embiotociform swimming are widely distributed within the Perciformes.

Journal Article↗
PubMed1996

Pectoral fin locomotion in the striped surfperch. I. Kinematic effects of swimming speed and body size

Swimming trials at increasing velocity were used to determine the effects of steady swimming speed on pectoral fin kinematics for an ontogenetic series of striped surfperch Embiotoca lateralis, ranging from 6 to 23 cm in standard length (SL). The fin stroke cycle consisted of a propulsive period, the duration of fin abduction and adduction, and a 'refractory' period, during which the fin remained adducted against the body. Pectoral fin-beat frequency (fp) measured as the inverse of the entire stride period, as in past studies, increased curvilinearly with speed. Frequency, calculated as the reciprocal of the propulsive period alone, increased linearly with speed, as shown previously for tail-beat frequency of fishes employing axial undulation. Fin-beat amplitude, measured as the vertical excursion of the pectoral fin tip during abduction, increased over a limited range of low speeds before reaching a plateau at 0.35­0.40 SL. Pectoral fin locomotion was supplemented by intermittent caudal fin undulation as swimming speed increased. At the pectoral­caudal gait transition speed (Up-c), frequency and amplitude attained maxima, suggesting that the fin musculature reached a physiological limit. The effects of body size on swimming kinematics differed according to the method used for expressing speed. At a given absolute speed, small fish used higher stride frequencies and increased frequency at a faster rate than large fish. In contrast, the relationship between fp and length-specific speed (SL s-1) had a greater slope for large fish and crossed that for small fish at high speeds. We recommend that comparisons across size be made using speeds expressed as a percentage of Up-c, at which kinematic variables influencing thrust are size-independent.

Journal Article↗
PubMed1996

Pectoral fin locomotion in the striped surfperch. II. Scaling swimming kinematics and performance at a gait transition

In this study, we report the first allometric equations relating gait parameters and swimming speed to body size for fish employing pectoral fin locomotion. Comparisons of locomotor kinematics and performance among striped surfperch (Teleostei: Embiotocidae) are made at the pectoral­caudal gait transition speed (Up-c). Up-c is considered to elicit physiologically equivalent levels of exercise in animals varying over 100-fold in body mass (Mb) by virtue of dynamically similar pectoral fin movements (constant duty factor, length-specific stride length and fin-beat amplitude) and size-independent propulsive efficiency. At Up-c, pectoral fin-beat frequency scales in proportion to Mb-0.12±0.03, a size-dependence consistent with that observed for stride frequency in fishes swimming by axial undulatory propulsion and in many running tetrapods. It is proposed that the similarity in the scaling of frequency in these vertebrate groups reflects an underlying similarity in the allometry of the maximal velocity of muscle shortening. Absolute Up-c (m s-1) generally increases with body size, but the fastest speeds are not exhibited by the largest animals. A pattern of declining performance in fish 23 cm in standard length and longer may be related to their disproportionately small fin areas and aspect ratios. The pronounced negative allometry of Up-c expressed as standard body lengths per second indicates that a given length-specific speed does not induce comparable levels of activity in large and small fish. Thus, normalization of swimming speed to body length may not be a sufficient correction for kinematic comparisons across size.

Journal Article↗
PubMed1996

The impact of housing status on health care utilization among persons with HIV disease.

This study sought to identify the prevalence of unstable housing situations, and for whom they occurred, and to examine differences in health care utilization by housing status. Housing status and inpatient and outpatient health care utilization of 1,851 HIV-infected individuals was ascertained through interviews. Nine percent of respondents were in unstable housing situations. Unstable housing was associated with significantly lower functional status. The unstably housed were more likely to visit an emergency room (p < 0.05) and had fewer ambulatory visits than persons with stable housing (p < 0.03). They incurred nearly five more hospital days and their average hospitalization was approximately 1.5 days longer than the stably housed, although these differences were not significant. Utilization of ambulatory care is lower among unstably housed persons with HIV disease, which may have led to their increased reliance upon emergency rooms and hospitals. Helping HIV-infected individuals maintain adequate housing could reverse this pattern.

Adult↗