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Biomedical subjects

L Levin

Publications and source records attributed to L Levin.

At least 37 records · Page 2Linked to original sources
PubMed2001

Douching practices among HIV infected and uninfected adolescents in the United States.

PURPOSE: To characterize sexual behaviors and sociodemographic factors that are associated with douching among geographically diverse adolescent women with and without HIV infection. METHODS: HIV infected subjects recruited preferentially and behaviorally comparable high-risk HIV uninfected subjects were enrolled in a prospective HIV study from 15 sites in 13 U.S. cities. Baseline interview data from 1996 to 1999 for females aged 12 to 19 years were analyzed using one-way analysis of variance and multiple logistic regression. RESULTS: Among the 342 females/young women, 74.9% were black (non-Hispanic), 11.1% Hispanic/Latina, and 14.0% white or other race/ethnicity; 63.5% were HIV infected. Young women who had dropped out of high school comprised 23.4% of subjects. In the 3 months before the interview, 179 (52.3%) adolescents had douched at least once. In a multivariable logistic regression model, recent douching was more common among sexually active females (OR = 2.2; 95% CI: 1.2-4.2), Blacks (OR = 2.2; 95% CI: 1.2-4.1 vs. Hispanics/Whites/others), females who dropped out of high school (OR = 2.1; 95% CI: 1.2-3.7), and HIV infected females (OR = 1.7; 95% CI: 1.04-2.7). CONCLUSIONS: In this nationwide study, adolescents who are sexually active, African-American, dropped out of high school, and HIV infected were most likely to douche. Interventions to discourage douching should pay special attention to these populations.

Adolescent↗
PubMed2001

Effect of topical alendronate on root resorption of dried replanted dog teeth.

Alendronate (ALN) is a third generation bisphosphonate with demonstrated osteoclast inhibitory activity that may slow down the resorptive process after severe traumatic injuries. Eighty-two premolar roots of five mongrel dogs were endodontically treated and restored, extracted and treated as follows: 70 roots were bench dried for either 40 or 60 min. Thirty-eight of these roots were then soaked for 5 min in a 1 mM solution of ALN in Hanks' Balanced Salt Solution (HBSS) and replanted. Thirty-two roots were soaked for 5 min in HBSS and replanted. In the remaining 12 roots which were not exposed to the bench drying procedure, a 0.5 mM deep lingual mid-root cemental defect was made. Six of these roots were soaked in a 1 mM solution of ALN in HBSS for 5 min and replanted. The other six roots were soaked for 5 min in HBSS and replanted. Historical negative and positive controls were used from similarly treated teeth in our previous studies. After 4 months the dogs were killed and the roots prepared for histological evaluation. Five-microm-thick cross-sections of the root and surrounding tissue taken every 70 microm were evaluated for healing according to the criteria of Andreasen. In the 12 roots with cemental defects, healing with cementum of the damaged root surface was evaluated. In addition, residual root mass was also measured to determine the extent of root structure loss for each soaking method. Cemental healing took place in all 12 artificially damaged roots, indicating that these soaking media did not inhibit cementogenesis. The alendronate-soaked roots had statistically significantly more healing than the roots soaked in HBSS without alendronate. This improvement in healing was seen in all dogs except one and in all teeth except the first premolar. Soaking in alendronate also resulted in significantly less loss in root mass due to resorption compared to those teeth soaked in HBSS without alendronate.

Administration, Topical↗
PubMed2001

Food selectivity and problem behavior in children with developmental disabilities. Analysis and intervention.

Excessive food selectivity typifies some children with developmental disabilities. We conducted functional analyses to determine the controlling variables for problem behavior that accompanied food selectivity and analyzed the role of establishing operations in ameliorating food selectivity. Specifically, we studied the differential effects on intervention efficacy of an individual's having or not having access to preferred food items prior to an intervention that involved the presence versus absence of a positive reinforcement contingency applied to food consumption. Participants displayed significantly more problem behavior during the nonpreferred-foods condition. Participants consumed nonpreferred target food items only when prior access to preferred foods was limited and a positive reinforcement contingency was implemented. Functional analysis suggested that problem behavior was maintained by negative reinforcement. Intervention data suggested that establishing operations increased the efficacy of the contingency-based intervention. The implications of applying this intervention in the community were discussed as were the relative merits of stimulus fading versus escape extinction intervention strategies.

Autistic Disorder↗
PubMed2001

How are age and payors related to avoidable hospitalization conditions?

OBJECTIVE: (1) Examine variations in AHC indicators across age groups and payor types; (2) evaluate the impact of individual and community characteristics on AHC indicators; and (3) investigate the effect of adjustment for age and other factors on AHC indicators. MCOs can use AHC hospitalization and inpatient days to develop focused strategies in reducing AHC hospitalization. But biased comparisons often occur without adjustment for confounding factors. This study demonstrates that age and age/gender adjustments are needed for privately insured and Medicare patients while additional adjustment for community characteristics is needed for Medicaid and Self-Pay patients.

Adolescent↗
PubMed2000

Sensitivity analysis of mercury human exposure.

We present a comprehensive analysis of the sensitivity of mercury (Hg) human exposure to environmental variables using a multimedia model of the fate and transport of Hg in the environment. The results of the analysis show that the Hg dose is most sensitive to the lake pH, the burial rate of Hg adsorbed to sediments, and the chemical speciation of Hg emissions to the atmosphere. The lake pH has a strong non-linear effect on the methylation rate and bioaccumulation of Hg in fish. The burial of sediments is a major pathway for removing Hg from the lake cycling. The speciation of Hg emissions is important because Hg(II) is deposited much more rapidly than Hg(0). These results highlight the importance of key variables that should be investigated through well-designed field programs, so that we can minimize the overall uncertainties associated with the modeling of mercury fate and transport.

Confounding Factors, Epidemiologic↗
PubMed2000

Prevalence of and risks for cervical human papillomavirus infection and squamous intraepithelial lesions in adolescent girls: impact of infection with human immunodeficiency virus.

CONTEXT: Data suggest that in adults, human papillomavirus (HPV) infections and their sequalae, squamous intraepithelial lesions (SILs), occur more commonly among human immunodeficiency (HIV)-infected women because of the HIV-associated CD4+ T-cell immunosuppression. Since adolescents are more likely to be early in the course of HIV and HPV infections, the study of both infections in this age group may help elucidate their initial relationship. OBJECTIVE: To examine the prevalence of and risks for cervical HPV infection and SILs by HIV status in a population of adolescent girls. PARTICIPANTS: Subjects recruited at each of the 16 different US sites participating in a national study of HIV infection in adolescents. MAIN OUTCOME MEASURES: Cervical HPV DNA findings using polymerase chain reaction detection techniques and Papanicolaou smear from baseline visits. Infection with HPV was categorized into low- (rarely associated with cancer) and high- (commonly associated with cancers) risk types. RESULTS: Of 133 HIV-infected girls, 103 (77.4%) compared with 30 (54.5%) of 55 noninfected girls were positive for HPV (relative risk [RR], 1.4; 95% confidence interval [CI], 1.1-1.8). The risk was for high-risk (RR, 1.8; 95% CI, 1.2-2.7) but not low-risk (RR, 1.2; 95% Cl, 0.4-3.9) HPV types. Among the girls with HPV infection, 21 (70.0%) of the non-HIV-infected girls had normal cytologic findings compared with only 29 (29.9%) of the HIV-infected girls (P<.001). Multivariate analysis showed that HIV status was a significant risk for HPV infection (odds ratio [OR], 3.3; 95% CI, 1.6-6.7) and SIL (OR, 4.7; 95% CI, 1.8-14.8), but CD4 cell count and viral load were not associated with infection or squamous intraepithelial lesions. Only 9 girls had a CD4+ T-cell count of less than 0.2 cell X 10(9)/L. CONCLUSIONS: High prevalence of HPV infection in both groups underscores the risky sexual behavior in this adolescent cohort. Rates of HPV infection and SILs were higher among HIV-infected girls, despite similar sexual risk behaviors and the relatively healthy state of our HIV-infected group. Infection with HIV may enhance HPV proliferation through mechanisms other than CD4 immunosuppression, particularly early in the course of HIV infection.

Adolescent↗
PubMed2000

Lack of serological evidence for Mycoplasma fermentans infection in army Gulf War veterans: a large scale case-control study.

Mycoplasma firmentans is suspected in the development of 'Gulf War illness' in veterans of Operation Desert Storm. We conducted a matched case-control study for the prevalence of M. firmentans-specific antibodies before and after the operation, as well as seroconversion rates in veterans with and without complaints of 'Gulf War illness'. Cases consisted of Gulf War veterans, who complained of various illnesses and were enrolled in the second phase of the health evaluation by the Army Comprehensive Clinical Examination Program (CCEP). Controls were selected from Gulf War veterans who did not participate in the registry and did not request a health evaluation by the CCEP. Before operation deployment, 34 out of 718 of the cases (48%) and 116 out of 2233 of the controls (5.2%) tested positive for M. fermentans-specific antibodies. There was no difference in rates of seroconversion between cases and controls (1.1 vs. 1.2%) to M. fermentans during Operation Desert Storm. Thus, there is no serological evidence that suggests infectionby M. fermentans is associated with development of 'Gulf War illness'.

Adolescent↗
PubMed2000

Computer simulations of ultrafiltration profiles for an icodextrin-based peritoneal fluid in CAPD.

BACKGROUND: The three-pore model of peritoneal transport has the ability to predict ultrafiltration (UF) profiles rather accurately, even when high molecular weight (MW) solutes are employed as osmotic agents in continuous ambulatory peritoneal dialysis (CAPD). In the present simulations, we wanted to assess, for various theoretical perturbations, the UF properties of a peritoneal dialysis (PD) solution with an osmotic agent having an average MW of 20 kD and a "number average MW" of 6.2 kD, which is similar to that of icodextrin (ICO). METHODS: For a PD solution containing a completely monodispersed 20 kD MW osmotic agent, the degree of UF modeled is much higher than that reported for ICO. Hence, to model the behavior of ICO, we subdivided the ICO molecules into eight or more different MW size fractions. For simulations using six or eight subfractions, we obtained an excellent fit of simulated to reported UF data. More dispersed solutions produced UF profiles similar to that with eight fractions. RESULTS: A 2.05 L 7.5% ICO PD solution, despite being slightly hypotonic, yielded a UF volume of nearly 600 mL in 12 hours, modeled for patients not previously exposed for ICO. After nine hours, the UF volume exceeded that produced by 3.86% glucose. The UF rate and volumes increased in proportion to (1) the ICO concentration, (2) the peritoneal surface area, and (3) the peritoneal UF coefficient, but was almost insensitive to increases in the instilled fluid volume. Simulated for patients previously exposed to ICO, having steady-state plasma concentrations of ICO degradation products, the predicted UF volume at 12 hours was reduced to approximately 400 mL. CONCLUSION: Employing the three-pore model of peritoneal transport and taking into account the polydispersed nature of ICO, it was possible to accurately computer simulate the UF profiles of ICO in accordance with reported data. The simulations suggest an advantage of using ICO in patients with type I UF failure, where UF with a high-MW osmotic agent will exceed that seen in patients not showing UF failure who are on glucose-based PD solutions.

Absorption↗
PubMed2000

The sensitivity of PM2.5 source-receptor relationships to atmospheric chemistry and transport in a three-dimensional air quality model.

Air quality model simulations constitute an effective approach to developing source-receptor relationships (so-called transfer coefficients in the risk analysis framework) because a significant fraction of particulate matter (particularly PM2.5) is secondary (i.e., formed in the atmosphere) and, therefore, depends on the atmospheric chemistry of the airshed. In this study, we have used a comprehensive three-dimensional air quality model for PM2.5 (SAQM-AERO) to compare three approaches to generating episodic transfer coefficients for several source regions in the Los Angeles Basin. First, transfer coefficients were developed by conducting PM2.5 SAQM-AERO simulations with reduced emissions of one of four precursors (i.e., primary PM, sulfur dioxide (SO2), oxides of nitrogen (NOx), and volatile organic compounds) from each source region. Next, we calculated transfer coefficients using two other methods: (1) a simplified chemistry for PM2.5 formation, and (2) simplifying assumptions on transport using information limited to basin-wide emission reductions. Transfer coefficients obtained with the simplified chemistry were similar to those obtained with the comprehensive model for VOC emission changes but differed for NOx and SOz emission changes. The differences were due to the parameterization of the rates of secondary PM formation in the simplified chemistry. In 90% of the cases, transfer coefficients estimated using only basin-wide information were within a factor of two of those obtained with the explicit source-receptor simulations conducted with the comprehensive model. The best agreement was obtained for VOC emission changes; poor agreement was obtained for primary PM2.5.

Air Pollutants↗
PubMed2000

Seroprevalence and risk factors of hepatitis B, hepatitis C, and human cytomegalovirus among HIV-infected and high-risk uninfected adolescents: findings of the REACH Study. Adolescent Medicine HIV/AIDS Research Network.

BACKGROUND AND OBJECTIVES: In adolescents and young adults, multiple studies have identified sexual activity and behaviors as significant risk factors for acquiring both human cytomegalovirus (HCMV) and hepatitis B virus (HBV). However, there are no reports on the prevalence or risk factors for infection of these viruses and hepatitis C virus (HCV) in an adolescent population with sexually acquired HIV. GOALS: To examine the seroprevalence and risk factors of HBV, HCV, and HCMV infection in a population of HIV-infected male and female adolescents and in an age- and risk behavior-matched HIV-uninfected cohort. STUDY DESIGN: A cross-sectional analysis of HBV, HCV, and HCMV infections in a cohort of HIV-infected and HIV-uninfected adolescents. RESULTS: Adolescent males infected with HIV were more likely to have evidence of HBV and HCMV infection than HIV-uninfected males (23.7% versus 0%, respectively, for HBV, P = 0.008; 79.7% versus 50%, respectively, for HCMV, P = 0.004). HIV-infected females were more likely to have evidence of HCMV infection (78.5% versus 61.4%, P = 0.003) than HIV-uninfected females. No significant difference was found for HBV infection in the two groups of females. The rate of HCV infection (1.6%) was too small to make comparisons between the groups. To determine whether the differences in infection rates for HBV and HCMV could be explained by factors other than HIV status, a variety of possible risk factors were examined using univariate and multivariate analyses. A significant risk factor for HBV and HCMV infections for males was a homosexual or bisexual orientation. For females, a risk factor for HBV infection was having more than 10 lifetime sexual partners; for HCMV infection, HIV infection was the only risk factor. In addition, in the HIV-infected cohort, 15% of females and 36% of males who were seropositive for HBV had evidence of active HBV infection. CONCLUSIONS: These results emphasize the need for continued development of primary and secondary prevention programs and clinical screening and treatment for HBV and HCMV in adolescents.

Adolescent↗
PubMed2000

Hemodynamic responses to ECT in a patient with critical aortic stenosis.

We present a case study of a 46-year-old woman with a psychotic depressive illness of 2 months' duration with the coexisting medical diagnoses of critical aortic stenosis, severe labile hypertension, renal failure necessitating hemodialysis of 7-years' duration, and systemic lupus. Because of unresponsiveness to an antidepressant drug regimen, severe motor retardation, mutism, and refusal of food and fluids by mouth, an urgent indication for electroconvulsive therapy (ECT) was established. However, the patient refused ECT, and to allow its initiation, a court order was obtained. In view of the coexisting diagnoses of critical aortic stenosis, labile hypertension, and renal failure, ECT represented a substantially increased risk in this patient because of severe arterial hypertension and tachycardia. The patient was successfully managed during each ECT, using a combination of metoprolol by mouth, which was supplemented by i.v. esmolol immediately prior to the application of the ECT stimulus, and sodium nitroprusside, which was infused for several minutes prior to the seizure and thereafter to attenuate arterial hypertension. Nevertheless, sudden death, a well-known complication of critical aortic stenosis, occurred 96 hours after the fourth ECT.

Aortic Valve Stenosis↗
PubMed2000

The effect of a cholecystokinin agonist on masseter muscle activity in the cat.

The CCK(B) agonist, pentagastrin, has been shown to induce anxiety in human subjects. Similarly, in the cat model, pentagastrin facilitates the expression of hypothalamically activated emotional behavior. Because hypothalamically mediated emotional behavior is also accompanied by increased EMG activity in the jaw muscles, these experiments were designed to examine the combined effects of administration of pentagastrin with activation of hypothalamically mediated emotional behavior upon jaw muscle EMG activity. Electrodes were carefully lowered through previously placed guide tubes overlying the hypothalamus until a behavioral site was identified. Following the establishment of a stable threshold current for eliciting an emotional behavioral response, the skin overlying the ipsilateral masseter muscle was shaved and cleaned with alcohol, and surface electrodes were attached. The EMG was recorded, amplified, digitized, and stored in a microcomputer for analysis. Mean power frequencies (MPF) and latencies for behavior were calculated for baseline prior to infusion of all drugs. Following this, the effects of intravenous administration of pentagastrin and the CCK(B) antagonist LY288513 on the MPF were determined. The infusion of the CCK(B) agonist, pentagastrin (0.77, 1.92, and 3.84 microg/kg), decreased MPF in a time-related manner. The effects of pentagastrin 1.92 microg/kg were blocked by the CCK(B) antagonist, LY288513 (6.54 microg/kg). In addition, the infusion of LY288513 alone increased MPF. These results are surprising in that pentagastrin's anxiogenic properties would appear to make it likely to facilitate motor activity, not suppress it.

Animals↗
PubMed1999

Member grievances in Medicare+Choice programs: a review of Grijalva v. Shalala.

On May 3, 1999, the U.S. Supreme Court overturned the decision of the Ninth Circuit Court of Appeals in the case of Grijalva v. Shalala. In Grijalva, the U.S. District Court in Arizona had handed down, and the Ninth Circuit Court had upheld, one of the most far-reaching decisions, greatly expanding the rights of Medicare beneficiaries enrolled in HMOs (i.e., Medicare + Choice plans) for filing grievances against their HMOs. This article explores the implications of the Supreme Court's decision, and the expanding appeal rights of Medicare beneficiaries and other HMO members under recently enacted state laws, as well as under the proposed Patient's Bill of Rights now being debated in Congress.

Aged↗
PubMed1998

Risk of melanoma in medium-sized congenital melanocytic nevi: a follow-up study.

BACKGROUND: The risk of the occurrence of malignant melanoma (MM) in medium-sized (1.5 to 19.9 cm in diameter) congenital melanocytic nevi (CMN) is the subject of controversy. Universally accepted recommendations regarding the management of such lesions have not been made. OBJECTIVE: Our purpose was to assess the risk of MM arising in medium-sized CMN. METHODS: The study included 230 medium-sized CMN in 227 patients, first seen in a private dermatology practice from 1955 to 1996, who were followed up for MM arising within their CMNs. Criteria for entry into the study included (1) a clinically diagnosed medium-sized CMN, (2) minimum follow-up period of 1 year, and (3) a photograph of the lesion in the patient's medical record. RESULTS: No MM occurred in a medium-sized CMN during an average follow-up of 6.7 years (median, 5.8 years) to an average age of 25.5 years (median, 19.1 years). CONCLUSION: The results of this short-term follow-up study do not support the view that there is a clinically significantly increased risk for MM arising in banal-appearing medium-sized CMN or that prophylactic excision of all such lesions is mandatory. Lifelong medical observation seems a reasonable alternative for many medium-sized CMN.

Adolescent↗
PubMed1998

Laboratory tests and imaging studies in patients with cutaneous malignant melanoma.

Laboratory tests and imaging studies are often ordered for asymptomatic patients with malignant melanomas (MMs) in an effort to detect subclinical metastatic disease. However, their sensitivity and specificity for detecting cryptic metastases are not well established. A review of the literature on laboratory tests and imaging studies for MM metastases was undertaken to address the usefulness of such investigations in asymptomatic patients with MM in AJCC (American Joint Committee on Cancer system of classification) stages I, II, and III. A review of the pertinent literature since 1966 was conducted through MEDLINE, Medica, and Cancerlit. Laboratory tests and imaging studies revealed occult MM metastases in only a small number of the thousands of reported patients with putative AJCC stage I, II, and III MM. However, for those diagnosed with limited metastases, surgical removal with or without immunotherapy, chemotherapy, or radiotherapy can lead to long-term remissions in some patients. For patients with asymptomatic AJCC stage I or II disease, chest roentgenograms (CXR) and blood lactic dehydrogenase (LDH) levels may be obtained at low cost and prove to be of benefit if metastases are identified. For patients with AJCC stage III disease, computed tomographic (CT) scans of the thorax, abdomen, and pelvis (especially when the primary cutaneous site of the melanoma is below the waist) may be considered for detecting metastatic MM. Other tests, such as magnetic resonance imaging (MRI) scans of the brain, may be ordered based on symptoms or physical findings. In the future, technologically improved techniques and newer methods may prove cost-effective for detecting treatable asymptomatic MM metastases. Furthermore, improvement in treatments will also influence the indications for the search for occult MM metastases. At this time there is a need for an international consensus conference on laboratory tests and imaging studies for occult melanoma metastases.

Clinical Chemistry Tests↗
PubMed1998

Teaching a student with autism to make verbal initiations: effects of a tactile prompt.

This study examined the effects of a tactile prompting device (the Gentle Reminder) as a prompt for a student with autism to make verbal initiations about his play activities. A multiphase multielement design was used to assess the effects of the device in prompting initiations toward an adult in three different play contexts. Follow-up probes were conducted during cooperative learning activities with typically developing peers in the student's regular education class. The results suggest that the device serves as an effective, unobtrusive prompt for verbal initiations during play contexts and during cooperative learning activities.

Autistic Disorder↗