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Biomedical subjects

S A Levy

Publications and source records attributed to S A Levy.

At least 19 recordsLinked to original sources
PubMed2001

Efficacy of an amitraz-impregnated collar in preventing transmission of Borrelia burgdorferi by adult Ixodes scapularis to dogs.

OBJECTIVE: To determine whether an amitraz-impregnated collar could prevent transmission of Borrelia burgdorferi by Ixodes scapularis to dogs. DESIGN: Laboratory trial. ANIMALS: 8 specific-pathogen-free Beagles. PROCEDURE: On days -15 and -1, all dogs had negative ELISA results for serum antibodies against B. burgdorferi. On day 0, 4 dogs were each fitted with an amitraz-impregnated (9%) collar, and 4 dogs served as untreated controls. On day 7, all dogs were infested with 100/scapularis (approx 50 females and 50 males) with a known B. burgdorferi infectivity rate of 39.4%. On days 21, 28, 35, 42, 56, 70, and 84, each dog was tested for serum antibodies against B. burgdorferi via ELISA and a western blot technique. Additional ELISA were also performed for serum antibodies against antigenically similar organisms. RESULTS: By day 70, all control dogs had developed serum ELISA responses ranging from 328 to 510 kinetics-ELISA units (equivalent to end-point titers of approx 43,500 to 60,000), whereas treated dogs remained seronegative throughout the study. Western blot assays performed on all serum samples confirmed that antibodies detected in control dogs reflected responses to specific antigens of B. burgdorferi, whereas treated dogs had no such antibodies. Additional serologic analyses confirmed that antibody responses observed in control dogs were not attributable to antigenically similar organisms. CONCLUSIONS AND CLINICAL RELEVANCE: Amitraz-impregnated collars prevented transmission of B. burgdorferi in 4 of 4 treated dogs and may be a useful management tool for prevention of borreliosis in dogs.

Animals↗
PubMed2001

Specifying the relations between affect and heavy alcohol use among young adults.

Current reformulations of the tension reduction hypothesis posit that only a subset of vulnerable individuals are at risk for drinking in response to negative affect. To further specify this model, this study examined the types of mood and social contexts under which affect and alcohol use are associated. Participants were 74 college students who completed repeated assessments of mood, alcohol use, friendship quality, and social support. A complex pattern of findings supported the moderating influences of gender, friendship factors, and the timing of behavior (i.e., weekends vs. weekdays) on the relation between affect and alcohol use. Young adults with less intimate and supportive friendships, as compared with their peers, showed risk for greater drinking following relative elevations in sadness and hostility. Such drinking episodes, in turn, predicted subsequent elevations in these same negative moods the following week. Gender differences in such a cyclical pattern of affect and alcohol use were found to vary across differing emotional experiences. Recommendations for a more refined theory of affect and alcohol use are discussed.

Adaptation, Psychological↗
PubMed1995

Serologic responses of dogs naturally exposed to or vaccinated against Borrelia burgdorferi infection.

OBJECTIVE: To characterize the serologic responses of dogs naturally exposed to or vaccinated against Borrelia burgdorferi and to assess responses at intervals after antibiotic treatment. DESIGN: Prospective, controlled clinical trial. ANIMALS: 19 dogs of various breeds and ages with narrowly defined clinical criteria of limb/joint borreliosis and 10 control dogs of equivalent age were used to determine serologic responses following natural exposure to the organism. Eight seronegative dogs were used to determine serologic responses following vaccination. PROCEDURE: Serologic responses to B burgdorferi and recombinant outer surface protein (Osp)A, flagellin, and P39 were assessed by means of ELISA and western immunoblot. Passive protective activity was assessed by use of a mouse protection assay. RESULTS: Naturally exposed dogs were seropositive, but had variable ELISA titers and immunoblot profiles. Immunoblot analysis did reveal consistent reactions to flagellin, P39, and a 22 kd protein, but not to OspA. Antibody responses did not change appreciably up to 13 weeks after antibiotic treatment. Vaccinated dogs had strong reactions to OspA and OspB, but not to P39. CLINICAL IMPLICATIONS: Dogs with clinical borreliosis are seropositive and remain seropositive after antibiotic treatment, emphasizing that serologic testing is not a useful means of measuring clinical response. Serologic responses of infected dogs can be discriminated from those of vaccinated dogs by means of immunoblot analysis, and recombinant P39 is a potentially useful antigen for that purpose.

Animals↗
PubMed1995

PRO-LIGAND: an approach to de novo molecular design. 1. Application to the design of organic molecules.

An approach to de novo molecular design, PRO-LIGAND, has been developed that, in the environment of a large, integrated molecular design and simulation system, provides a unified framework for the generation of novel molecules which are either similar or complementary to a specified target. The approach is based on a methodology that has proved to be effective in other studies--placing molecular fragments upon target interaction sites-but incorporates many novel features such as the use of a rapid graph-theoretical algorithm for fragment placing, a generalised driver for structure generation which offers a large variety of fragment assembly strategies to the user and the pre-screening of library fragments. After a detailed description of the relevant modules of the package, PRO-LIGAND's efficacy in aiding rational drug design is demonstrated by its ability to design mimics of methotrexate and potential inhibitors for dihydrofolate reductase and HIV-1 protease.

Computer Simulation↗
PubMed1993

Performance of a Borrelia burgdorferi bacterin in borreliosis-endemic areas.

The safety and efficacy of a commercially available Borrelia burgdorferi bacterin were examined under field conditions in 1,969 dogs that received a total of 4,033 doses of bacterin during a 20-month period. For comparison, 4,498 dogs that were not vaccinated also were evaluated. All dogs were examined at 1 of 3 veterinary practices in borreliosis-endemic areas. Owners of all dogs were educated about the benefits of and methods for avoiding infected ticks. Vaccination was found to be safe regardless of previous exposure to B burgdorferi or history of borreliosis. Thirty-eight (1.9%) of the 1,969 dogs had minor reactions; 1 of these dogs had a reaction after the first and second doses of B burgdorferi bacterin. Reactions resolved without complications immediately or within 72 hours after vaccination. Cumulative incidence of borreliosis was 1.0% (20/1,969) in vaccinated dogs and 4.7% (211/4,498) in nonvaccinated dogs. Preventable fraction, a measure of the reduction of incidence of disease in vaccinated dogs vs nonvaccinated dogs, was 78%. Preventable fraction in dogs that were seropositive prior to vaccination (ie, previously exposed to B burgdorferi) was 58% and in dogs that were seronegative prior to vaccination (ie, without evidence of prior exposure to B burgdorferi) was 86%. This suggested that, in borreliosis-endemic areas, dogs may be most effectively protected by vaccinating them when they are young and before they are exposed to infected ticks, and that in areas where borreliosis is not endemic, it may be useful to initiate vaccination programs so that dogs will be protected prior to exposure to infected ticks.

Animals↗
PubMed1992

Relationship between development of antibodies to Borrelia burgdorferi in dogs and the subsequent development of limb/joint borreliosis.

The relationship between antibody production and the subsequent development of limb/joint disorders of borreliosis was examined in dogs from south central Connecticut. Dogs without signs of illness, determined by physical examination, were selected from dogs being tested for Dirofilaria immitis. An ELISA was used to detect antibodies to Borrelia burgdorferi in 234 apparently healthy dogs during 1988. These dogs were monitored for 20 months after initial analyses to determine the prevalence of limb/joint disorder in seropositive and seronegative dogs. Of 234 dogs from which samples were initially obtained, 125 had antibodies to B burgdorferi and 109 were seronegative. The development of limb/joint disorder (eg, lameness, swelling, and signs of pain) accompanied by lethargy, fever, and inappetence in each group was nearly equal. Rates of 4.8% (6/125) and 4.6% (5/109) were recorded for seropositive and serosurvey of dogs, respectively. We conclude the serosurvey of apparently healthy dogs had no predictive value for the subsequent development of limb/joint disorder.

Animals↗
PubMed1990

Tick parasitism and antibodies to Borrelia burgdorferi in cats.

Ticks were removed from naturally infested cats, and serum samples from these cats were tested for antibodies to Borrelia burgdorferi. Twenty-two of 93 cats (23.7%) had one or more motile stages of Ixodes dammini attached. Of 2 larvae and 20 nymphs removed from cats, 1 larva and 2 nymphs were infected with B burgdorferi. Spirochetes were not found in tissues of 13 female and 4 male ticks. Ten of 71 serum samples analyzed by indirect fluorescent antibody staining or ELISA contained antibodies to this spirochete. Maximal antibody titers were 1:256 and 1:2,560, respectively. At titers greater than or equal to 1:160 in ELISA, seropositivity ranged from 8.8% (n = 34 sera tested from 34 cats) in May through July to 33.3% (n = 12 cats tested) during February through April. In clinical studies of 30 cats, there were nearly equal percentages of seropositive cats with limb or joint disorders not accompanied by fever, anorexia, or fatigue (5 of 21 cats) and cats with these signs of illness but lacking lameness (2 of 9 cats.)

Animals↗
PubMed1986

Renin-angiotensin II-aldosterone and ACTH-cortisol control during acute hypoxemia and exercise in patients with chronic obstructive pulmonary disease.

Acute hypoxia has been reported to induce a decrease in aldosterone levels despite no change or increases in plasma renin activity and ACTH. Converting enzyme inhibition and/or mild hypokalemia have been suggested as possible mechanisms for this dissociation. We studied 15 patients with chronic obstructive pulmonary disease (COPD) who used continuous ambulatory O2 therapy (home O2). Group A (n = 10) had O2 discontinued for 30 min before exercise to induce hypoxemia; Group B (n = 5) had O2 continued for 30 min (time control). Discontinuation of home O2 in Group A resulted in a significant fall in Pao2 from 77 +/- 6 to 51 +/- 2 torr. Arterial CO2 tension decreased and the pHa increased slightly. Renin, angiotensin II, plasma potassium, and sodium did not change during hypoxemia, whereas ACTH increased significantly. Despite this, aldosterone decreased from 26 +/- 5 to 18 +/- 2 ng/dl. Group B (time control) did not exhibit significant changes in hormones over 30 min, indicating that the effects observed in Group A were specific to O2 discontinuation. Exercise in Group A induced significant increases in ACTH, potassium, and aldosterone. We conclude from these data that acute hypoxemia in patients with COPD results in a decrease in aldosterone not related to converting enzyme inhibition, ACTH, or plasma potassium.

Adolescent↗
PubMed1978

Meat worker's asthma.

A meat cutter who experienced wheezing when working in the area where price labels were heated, was challenged with the inhalation of the emission of heated price labels and nebulized phthalic anhydride. Only exposure to the emissions from the heated price labels evoked a response. The spectrum of emissions from heated price labels, analyzed by gas chromatography and mass spectrometry, was found to include phthalic anhydride, 2,5-di-tert-amyl quinone and dicyclohexylphthalate.

Asthma↗