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Biomedical subjects

M L Levin

Publications and source records attributed to M L Levin.

At least 19 recordsLinked to original sources
PubMed2001

Hiv-associated nephropathy occurring before HIV antibody seroconversion.

It currently is thought that human immunodeficiency virus-associated nephropathy (HIVAN) occurs late in the course of HIV infection. Although HIVAN may be the presenting manifestation of acquired immunodeficiency syndrome (AIDS), it usually occurs after a prolonged period of viral infection often associated with high levels of HIV viremia. The patient described here developed HIVAN as a manifestation of acute retroviral syndrome. A 41-year-old black man presented with nephrotic range proteinuria, renal insufficiency, and acute gastrointestinal and pulmonary symptoms. He recently had been treated for primary syphilis. Two HIV serologic tests, performed 3 months apart, were negative. Renal biopsy was consistent with HIVAN. After the biopsy, the patient was discovered to have more than 700,000 viral copies per mL in his blood. CD4(+) count was greater than 500/mm(3). Six weeks later, enzyme-linked immunosorbent assay and Western blot analyses for HIV antibody became positive. HIVAN can occur early in the course of HIV infection, even during acute infection before seroconversion, and prolonged exposure to virus is not necessary for this renal involvement to occur in the susceptible host.

AIDS-Associated Nephropathy↗
PubMed2001

Interference between the agents of Lyme disease and human granulocytic ehrlichiosis in a natural reservoir host.

Agents of Lyme disease (Borrelia burgdorferi) and human granulocytic ehrlichiosis (Ehrlichia phagocytophila) are perpetuated in a natural cycle involving the black-legged tick (Ixodes scapularis) and its vertebrate hosts. Using I. scapularis nymphs as the mode of infectious challenge, we studied how infection with one pathogen in white-footed mice (Peromyscus leucopus) affects their ability to acquire the other agent and subsequently to infect larvae, which these agents would do in nature. Two groups of mice were infected with either B. burgdorferi or E. phagocytophila. One week later, B. burgdorferi-infected mice were challenged with E. phagocytophila, and E. phagocytophila-infected mice were challenged with B. burgdorferi. Simultaneously, two control groups of uninfected mice were infected with each agent from the same tick cohorts used on the first groups of mice. Uninfected I. scapularis larvae were fed on all mice for xenodiagnosis at weekly intervals lasting 2 months. For the B. burgdorferi challenge, all control and E. phagocytophila-infected mice acquired B. burgdorferi. However, fewer xenodiagnostic larvae acquired B. burgdorferi from mice with mixed infections compared with mice infected with B. burgdorferi only. For the E. phagocytophila challenge, all five control mice acquired E. phagocytophila, but only two of five mice infected with B. burgdorferi subsequently acquired E. phagocytophila. Consequently, mice with both infections produced fewer xenodiagnostic ticks infected with E. phagocytophila than mice infected with E. phagocytophila only. Thus, a primary infection with either B. burgdorferi or E. phagocytophila in mice inhibited transmission of a second agent, suggesting interference between these two agents.

Anaplasma phagocytophilum↗
PubMed2001

The prevalence of Borrelia burgdorferi sensu lato in Ixodes persulcatus and I. ricinus ticks in the zone of their sympatry.

A total of 7210 unfed adult Ixodes persulcatus Schulze, 1930 and I. ricinus (L., 1758) ticks were collected from the vegetation by flagging in 35 study sites located in the zone of their sympatry (mainly in Leningrad region, Russia). Borrelia infection in ticks was estimated by the dark-field microscopic analysis of gut contents in standard vital preparations at a magnification of x600. No correlation was revealed between the series of parameters characterising the abundance of each tick species (tau = -0.13) and between the series of these parameters and the prevalence of Borrelia in each vector. It is concluded that in the broad zone of I. persulcatus and I. ricinus sympatry, the presence and proportion of one vector in the ecosystem does not have any significant effect on the extensity of infection and on the epizootic and epidemic significance of the other vector. Each tick species has its independent (of the other species) and relatively original functional role in the focal ecosystem.

Animals↗
PubMed2000

Immunity reduces reservoir host competence of Peromyscus leucopus for Ehrlichia phagocytophila.

Infection with Ehrlichia phagocytophila in white-footed mice is transient and followed by a strong immune response. We investigated whether the presence of acquired immunity against E. phagocytophila precludes white-footed mice from further maintenance of this agent in nature. Mice were infected with E. phagocytophila via tick bite and challenged either 12 or 16 weeks later by Ixodes scapularis nymphs infected with the same agent. Xenodiagnostic larvae fed upon each mouse simultaneously with challenging nymphs and 1 week thereafter. Ticks were tested for the agent by PCR, and the prevalence of infection was compared to that in ticks that fed upon nonimmune control mice. Only 30% of immunized mice sustained cofeeding transmission of E. phagocytophila between simultaneously feeding infected and uninfected ticks, compared to 100% of control mice. An average of 6.3% of xenodiagnostic ticks acquired Ehrlichia from previously immunized mice when fed 1 week after the challenge, compared to 82.5% infection in the control group. Although an immune response to a single infection with E. phagocytophila in white-footed mice provided only partial protection against reinfection with the same agent, the majority of mice were rendered reservoir incompetent for at least 12 to 16 weeks. Immunity acquired by mice during I. scapularis nymphal activity in early summer may exclude a large proportion of the mouse population from maintaining E. phagocytophila during the period of larval activity later in the season.

Animals↗
PubMed2000

Acquisition of coinfection and simultaneous transmission of Borrelia burgdorferi and Ehrlichia phagocytophila by Ixodes scapularis ticks.

The agents of Lyme disease (Borrelia burgdorferi) and human granulocytic ehrlichiosis (Ehrlichia phagocytophila) are both transmitted by the tick Ixodes scapularis. In nature, ticks are often infected with both agents simultaneously. We studied whether previous infection with either Borrelia or Ehrlichia in ticks would affect acquisition and transmission of a second pathogen. Ehrlichia-infected I. scapularis nymphs were fed upon Borrelia-infected mice, and Borrelia-infected I. scapularis nymphs were fed upon Ehrlichia-infected mice. The efficiency with which previously infected nymphal ticks acquired a second pathogen from infected hosts was compared to that of uninfected ticks. An average of 51% +/- 15% of ticks acquired Ehrlichia from infected mice regardless of their prior infection status with Borrelia. An average of 85% +/- 10% of ticks acquired Borrelia from infected mice regardless of their prior infection status with Ehrlichia. Also, we assessed the efficiency with which individual nymphs could transmit either agent alone, or both agents simultaneously, to individual susceptible hosts. An average of 76% +/- 9% of Borrelia-infected ticks and 84% +/- 10% of Ehrlichia-infected ticks transmitted these agents to mice regardless of the presence of the other pathogen. There was no evidence of interaction between the agents of Lyme disease and human granulocytic ehrlichiosis in I. scapularis ticks. The presence of either agent in the ticks did not affect acquisition of the other agent from an infected host. Transmission of the agents of Lyme disease and human granulocytic ehrlichiosis by individual ticks was equally efficient and independent. Dually infected ticks transmitted each pathogen to susceptible hosts as efficiently as ticks infected with only one pathogen.

Animals↗
PubMed1999

Proximal 5p trisomy resulting from a marker chromosome implicates band 5p13 in 5p trisomy syndrome.

We describe an infant with trisomy of (5)(p10p13.1) resulting from a de novo marker chromosome. The marker's origin was identified by chromosome microdissection and reverse in situ hybridization. The clinical findings are compared to those of other partial and complete 5p duplications. This case further defines the critical region of 5p trisomy syndrome to proximal 5p.

Abnormalities, Multiple↗
PubMed1999

Comparative vector competence of Dermacentor variabilis and Ixodes scapularis (Acari: Ixodidae) for the agent of human granulocytic ehrlichiosis.

Vector competence of Ixodes scapularis Say and Dermacentor variabilis Say for the agent of human granulocytic ehrlichiosis (HGE) was compared. Five white-footed mice, Peromyscus leucopus Rafinesque, were inoculated intra-peritoneally with blood from a mouse infected with the agent of HGE. Approximately 100 I. scapularis and D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Fed larvae were collected, separated according to species and allowed to molt to nymphs. Twenty-six per cent of I. scapularis (34/131) and 11% of D. variabilis (11/96) tested positive for the agent of HGE by polymerase chain reaction (PCR) after molting to nymphs. Positive I. scapularis nymphs transmitted the agent of HGE to P. leucopus mice in 5 of 5 trials. In contrast, the positive D. variabilis nymphs did not transmit the agent of agent of HGE in any of 6 trials. In a 2nd experiment, 3 P. leucopus mice were infested with I. scapularis nymphs that were infected with the agent of HGE. All 3 mice became infected with the agent of HGE and approximately 300 D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Larvae were collected and allowed to molt to nymphs as before. Approximately 8% (5/60) of the nymphs became positive for the agent of HGE as determined by PCR. Twenty-five of these nymphs were then placed on each of 9 P. leucopus mice and allowed to feed to repletion. Evidence of transmission was not observed in any of 9 mice exposed to D. variabilis nymphs. These results demonstrate that although I. scapularis is a competent vector of the agent of the HGF, D. variabilis is not.

Anaplasmataceae↗
PubMed1999

AIDS knowledge, condom attitudes, and risk-taking sexual behavior of substance-abusing juvenile offenders on probation or parole.

AIDS knowledge, condom attitudes, and sexual behavior were examined in a sample of 193 substance-abusing juvenile offenders on probation or parole. The majority of these youths reported being sexually active, and many admitted to early onset of sexual activity as well as unsafe sexual practices. Potential predictors of condom use by these juveniles were examined including age, condom use at first sexual experience, number of sexual partners in the last 6 months, locus of control, AIDS knowledge, condom attitudes, perceived risk for AIDS, self-efficacy for avoiding HIV, condom use by peers, delinquency risk, race, and gender. General attitudes toward condoms and the reported use of a condom at first sexual intercourse experience were the only statistically significant predictors of subsequent condom use. The relevance of these findings to the development of AIDS prevention programs for juvenile offenders is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Management of pain in terminally ill patients: physician reports of knowledge, attitudes, and behavior.

Physician knowledge, attitudes, and reported prescribing behaviors toward pain management in terminally ill patients was surveyed among primary care physicians (PCPs) and oncologists in a southern urban county. Response rates were 64% for PCPs and 100% for oncologists. The effects of knowledge and attitudes on reported behavior were analyzed after accounting for physician demographics, training, and experiences. Oncologists' knowledge and attitudes were close to ideal and behaviors less so. PCPs' knowledge was worse than oncologists, and attitudes and behaviors were even less optimal. Reported behaviors among PCPs correlated somewhat with attitudes, less with background factors, and rarely with knowledge. In multivariate analysis, demographic and experimental factors explained more of selected behaviors than attitudes or knowledge. However, all variables combined left the majority of variation in behaviors unexplained. Physician continuing education will not effect significant behavioral changes in the care of terminally ill patients solely by the traditional approach of attempting to modify knowledge and attitudes.

Health Knowledge, Attitudes, Practice↗
PubMed1998

Patterns of condom use among adolescents: the impact of mother-adolescent communication.

OBJECTIVES: The association between the timing of discussions about condoms between mother and adolescent and adolescents' condom use during their first and subsequent sexual encounters was examined. METHODS: Sexually active adolescents reported whether and when they discussed condoms with their mother and answered questions about their own condom use. RESULTS: Mother-adolescent discussions about condoms that occurred prior to sexual debut were strongly associated with greater condom use during first intercourse and most recent intercourse, along with greater lifetime regular condom use. CONCLUSIONS: Discussions about condoms prior to sexual debut are important in promoting condom use among adolescents.

Adolescent↗
PubMed1998

Density-dependent factors regulating feeding success of Ixodes scapularis larvae (Acari: Ixodidae).

We studied the effects of different parasite and host densities on the feeding success of larval Ixodes scapularis ticks upon white-footed mice Peromyscus leucopus. Mice were infested daily with 10, 25, 50, or 100 larvae and kept individually or in groups of 2 and 3 to simulate co-nesting in the field. Engorgement weight and molting success of replete larvae did not change during more than 3 wk of continuous infestation, but overall larval feeding success decreased from 24% to 12% with increased infestation density. Grooming was observed in response to unattached, crawling larvae, and grooming of unfed ticks increased with infestation density. Nearly all larvae completed engorgement once attached, although a few were groomed accidentally along with unattached ticks. Co-nesting mice fed 2-3 times fewer ticks than did solitary mice because of increased frequency of self-grooming in the presence of nest-mates, but differences between groups of 2 or 3 mice were not significant. Thus, increased mouse density may reduce the density of the tick population at first, but further increase in the number of co-nesting mice does not affect the feeding success of larval I. scapularis and increased mouse density will increase tick density.

Anesthesia↗
PubMed1997

The Pointer syndrome: a new syndrome with skeletal abnormalities, camptodactyly, facial anomalies, and feeding difficulties.

We describe a brother and sister with a unique combination of skeletal findings including camptodactyly (phalangeal dislocations), facial anomalies, neonatal respiratory problems, and feeding problems due to poor suck. Metaphyseal splaying, osteopenia, endosteal bone apposition, campomelia, and multiple fractures characterize the other skeletal abnormalities. The parents are first cousins once removed and are unaffected. These cases appear to represent a previously undescribed autosomal recessive disorder.

Abnormalities, Multiple↗
PubMed1997

Adolescent heterosexual experience: a new typology.

PURPOSE: The purpose of this paper is to define a typology that encompasses the full range of adolescent heterosexual behavior; to compare the usefulness of the new typology with that of the traditional dichotomy of "sexually active"/"sexually inactive" for understanding sexual behavior among adolescents; and to determine the implications of the new typology for the design and implementation of HIV prevention programs targeting adolescents. METHODS: Detailed face-to-face interviews were conducted with a cross-sectional sample of 907 mothers and their adolescents, ages 14-17 years, recruited from public high schools in Alabama, New York, and Puerto Rico. Information from the adolescent survey on precoital sexual behaviors and STD/HIV sexual risk and risk reduction behaviors was examined. A typology of adolescent heterosexual experiences was constructed using four behavioral dimensions. RESULTS: Ninety-nine percent (n = 894) of the sample was classified into one of the five patterns of sexual experience: Delayers, Anticipators, One-timers, Steadies, and Multiples. Among the participants who were not sexually active, precoital behaviors differed significantly between the 22% who anticipated initiating sexual intercourse in the next year (Anticipators) and those who did not (Delayers). Among those traditionally classified as "sexually active", One-timers and Steadies were significantly older when they first had penile-vaginal intercourse than those who had multiple partners. One-timers were more likely to use condoms than Steadies or Multiples, and only Multiples reported previous STDs. CONCLUSION: A typology that defines a range of adolescent heterosexual experiences was developed, and it was possible to classify 99% of our sample. The traditional dichotomy between "sexually active" vs. "not active" hides important behavioral intentions and sexual practices. These differences must be taken into account in the development and implementation of HIV prevention programs that target adolescents.

Adolescent↗
PubMed1996

A comparative transcription map of the murine bare patches (Bpa) and striated (Str) critical regions and human Xq28.

The X-linked developmental mouse mutations bare patches (Bpa) and striated (Str) may be homologous to human X-linked dominant chondrodysplasia punctata (CDPX2) and incontinentia pigmenti (IP2), respectively, based on their genetic mapping and clinical phenotypes. Bpa and Str have been localized to an overlapping critical region of 600 kb that demonstrates conserved gene order with loci in human Xq28 between DXS1104 and DXS52. As part of efforts to isolate the genes involved in these disorders, we have begun to develop a comparative transcription map spanning this region in both species. Using techniques of cross-species conservation and hybridization, exon trapping, and cDNA selection we have identified four known genes or members of gene families--caltractin, a member of the gamma-aminobutyric acid (GABAA) receptor gene family, a member of the melanoma antigen gene (MAGE) family, and several members of the murine-specific, X-linked lymphocyte regulated gene (Xlr3) family. Trapped exons and, in some cases, longer cDNAs have been isolated for potentially 7-9 additional genes. One cDNA demonstrates highly significant homology with members of the Krüppel family of zinc finger transcription factors. A second novel cDNA demonstrates homology at the 3' end of the predicted amino acid sequence to a LIM domain consensus. Gene order appears conserved among those cDNAs determined to be present in both human and mouse. Three of the murine transcripts appear to be present in multiple copies within the Bpa/Str critical region and could be associated with a predisposition to genomic rearrangements. Reverse transcriptase PCR (RT-PCR) and Northern analysis demonstrate that several of the transcripts are expressed in mid-gestation murine embryos and neonatal skin, making them candidates for the Bpa and Str mutations and their respective homologous human disorders.

Amino Acid Sequence↗
PubMed1995

Unique de novo interstitial deletion of chromosome 17, del(17) (q23.2q24.3) in a female newborn with multiple congenital anomalies.

We describe a newborn with a novel interstitial deletion of the long arm of chromosome 17 [del (17) (q23.2q24.3)] who died on day of life 17 during a recurrent apneic episode. Her phenotype included severe growth retardation, multiple facial anomalies, maldeveloped oralpharyngeal structures, and digital and widespread skeletal anomalies. This patient's phenotype was compared to two other reported patients with deletion 17q with minor clinical overlap consistent with a unique deletion.

Abnormalities, Multiple↗
PubMed1995

Acute renal failure in the elderly: strategies for prevention. How the physiologic effects of aging increase nephrotoxic risk.

Elderly patients are susceptible to acute renal failure largely because of functional impairment of the kidneys secondary to diseases such as arteriosclerosis, hypertension, and heart failure. Successful prevention of renal failure in the elderly hinges on understanding the age-associated changes in renal anatomy and physiology. To prevent renal failure, rehydrate elderly patients who suffer significant fluid loss to avoid volume depletion. In addition, maintain adequate blood pressure in these patients, consider glomerular filtration rate when determining the dosage of nephrotoxic antibiotics, and administer saline preparation before injecting radiocontrast dyes.

Acute Kidney Injury↗