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Biomedical subjects

N Janz

Publications and source records attributed to N Janz.

7 recordsLinked to original sources
PubMed2001

Evolutionary dynamics of host-plant specialization: a case study of the tribe Nymphalini.

Two general patterns that have emerged from the intense studies on insect-host plant associations are a predominance of specialists over generalists and a taxonomic conservatism in host-plant use. In most insect-host plant systems, explanations for these patterns must be based on biases in the processes of host colonizations, host shifts, and specialization, rather than cospeciation. In the present paper, we investigate changes in host range in the nymphalid butterfly tribe Nymphalini, using parsimony optimizations of host-plant data on the butterfly phylogeny. In addition, we performed larval establishment tests to search for larval capacity to feed and survive on plants that have been lost from the female egg-laying repertoire. Optimizations suggested an ancestral association with Urticaceae, and most of the tested species showed a capacity to feed on Urtica dioica regardless of actual host-plant use. In addition, there was a bias among the successful establishments on nonhosts toward plants that are used as hosts by other species in the Nymphalini. An increased likelihood of colonizing ancestral or related plants could also provide an alternative explanation for the observed pattern that some plant families appear to have been colonized independently several times in the tribe. We also show that there is no directionality in host range evolution toward increased specialization, that is, specialization is not a dead end. Instead, changes in host range show a very dynamic pattern.

Animals↗
PubMed1996

Girl Talk: development of an intervention for prevention of HIV/AIDS and other sexually transmitted diseases in adolescent females.

The number of adolescent females between the ages of 13 and 19 who are contracting sexually transmitted diseases (STDs) is rising at an alarming rate. Although the issue of STDs has been overshadowed by continued public debate over adolescent pregnancy and childbearing, it demands attention. Particularly concerning is the fact that STDs increase the likelihood of transmitting HIV (N.E. MacDonald et al., 1990). To offset the growing incidences of STDs among female adolescents, gender-specific interventions are needed. Following is a description of the theoretical underpinnings that informed and guided the development of a gender-specific intervention titled Girl Talk. A two-stage creation and review process was used to design this 2.5-hr, four-session intervention. An overview of the quasi-experimental design that compared a nonequivalent comparison and two intervention groups (peer led and adult led) is presented. Baseline characteristics of the three groups are reported. Also described is how participant feedback and a design content analysis are used to evaluate the appropriateness of the intervention for adolescent females.

Adolescent↗
PubMed1982

Symptomatic bradyarrhythmias in the adult: natural history following ventricular pacemaker implantation.

The preimplantation arrhythmias, coexistent medical conditions, the causes of death, and survival course are described for 399 patients who received their initial ventricular pacemaker implantation for a bradyarrhythmia (AV block, sinus node disease, and hypersensitive carotid sinus syndrome) at the University of Michigan from 1961 to 1979. Factors which correlated with a poor survival are elucidated. Survival for those with sinus node disease was virtually identical to those with AV block, with only 63% surviving over five years. Advanced age and congestive heart failure prior to implantation, and underlying ischemic or hypertensive heart disease portended a poorer survival in both groups. Patients with hypersensitive carotid sinus syndrome had a distinctly better prognosis--no deaths occurred until the eight year after pacing. Patients with no underlying heart disease and those with valvular disease did remarkably better than those with an ischemic or myopathic etiology. Apparent progression or complications of the underlying heart disease was the major cause of mortality. Sudden death, congestive heart failure, myocardial infarction, and major arrhythmias were the causes of death in 48% of those who died. Implications of improved pacing modalities on late complications and death are discussed.

Aged↗
PubMed1980

Suicide attempt by pacemaker system abuse: a case report with comments on the psychological adaptation of pacemaker patients.

Thirty patients selected at random from a pacemaker clinic were interviewed to gain an understanding of how psychological symptoms in these patients related to their cardiac condition. In 20% veiled depression or even a wish to die was elicited. Joking, fantasies, and denial were common psychological mechanisms used to adapt to their illness and the pacemaker itself. A dramatic example of attempted suicide in which the patient tried to cut the subcutaneously implanted pacemaker leads is presented and illustrated.

Adaptation, Psychological↗