Sleep need in adolescents: a longitudinal approach

A sample of 190 male and female "high school" students completed a sleep questionnaire for the first time when they were 10 to 14 years old. The survey was repeated five times at 2 year intervals. Ninety-three subjects answered the questionnaire each time. Subjective sleep need was assessed by the indicated wish for more sleep. The wish for more sleep was very pronounced, varying between 54.3% and 74.5% across the years. Individual consistency, however, was low since only 14.5% of the adolescents indicated the wish for more sleep in each survey, emphasizing the state dependency of this variable. Within each total sample, subjects with the wish for more sleep (MSL) and with sufficient sleep (SSL) were compared. Subjective sleep need was consistently validated by a syndrome of morning-tiredness. In the last two surveys, there was reduced time in bed (TIB) on weekdays in MSL subjects and longer TIB during vacation in surveys 2 through 5. Furthermore, MSL subjects more often showed irregular sleep habits. The previous sleep history of the MSL subjects in the last survey indicated that concomitants of the wish for more sleep were already experienced earlier in adolescence. The desired sleep duration of these subjects was 1.7 h longer than their current sleep on weekdays, an amount they had not obtained on weekdays since early adolescence. It is concluded that a substantial proportion of the adolescents seem to have had difficulties adapting to the general sleep time reduction occurring in adolescence.     

Age-related profile of cardiovascular reactivity to norepinephrine and angiotensin II in normal and hypertensive man

Summary The interrelationships among age, cardiovascular pressor reactivity to intravenously infused norepinephrine (NE) or angiotensin II, and endogenous plasma NE or renin (PRA) levels were evaluated in 31 normal subjects and 37 patients with essential hypertension. In normal subjects both angiotensin II pressor dose and PRA decreased progressively with aging. Angiotensin pressor dose correlated positively with PRA (r=0.41,P<0.025) and inversely with age (r=–0.46,P<0.02). NE pressor dose and basal plasma NE were also positively correlated (r=0.53,P<0.005), but the two factors remained largely unchanged with aging. Findings in essential hypertension differed in certain aspects. Angiotensin II pressor dose did not correlate with either basal PRA or age; and pressor doses of NE and angiotensin II tended to be lower in some patients than in normal subjects. These findings indicate that aging is accompanied by a physiologic increase in cardiovascular reactivity to angiotensin II, probably due to a concomitant decrease in circulating renin. The dissociation between angiotensin pressor dose and PRA in essential hypertension suggests an interference from an other factor.This work was supported by the Swiss National Science Foundation     

A short-term quantitative XC assay for murine leukemia virus.

A syncytial-plaque (SXC) assay for murine leukemia virus is described which utilizes a single cycle of infection, thus allowing quantitation of virus-producing mouse cells in 3 to 4 days. Depending upon the Fv-1 genotype of infected mouse cells, the assay will reflect single or multiple “hitness” after infection by N- or B-tropic MuLV. The test is equally sensitive to the uv-XC plaque assay for tissue culture adapted MuLV, but is less sensitive to in vivo derived MuLV from an AKR/J mouse. Newly isolated AKR MuLV requires a longer latent period than the in vitro adapted Moloney strain of MuLV.     

Craniofacial serial dimensions related to age, sex, and cleft-type from six months of age to two years.

The first two postnatal years are a time of rapid craniofacial growth. We selected 30 cleft lip/palate children, each seen at 6, 12, 18, 24 months, at which time lateral X-ray headfilms were taken. There were five boys, five girls, in each of three cleft-types: cleft palate only (CP), unilateral cleft lip/palate (UCLP), and bilateral cleft lip/palate (BCLP). Three dimensions were selected: 1) anterior cranial base (S-N); 2) upper face height (N-Pt.A); 3) maxillary depth (Pt.A-Ptm). All were in the midsagittal plane. This is a repeated measures study on the factor patient age, so that for each combination of sex and cleft-type the same subject was measured at the four levels of patient age. The multiple comparison technique utilized was the Newman-Keuls Procedure. There is no significant joint effect in the 6-24 months period. The factors seem to operate singly. There is no main effect due to the factor sex. Dimensions N-Pt.A. and Pt.A-Ptm show a significant main effect due to the factor cleft-type. There is a highly significant main effect due to the patient age factor.     

Increasing access to medical education for students from medically underserved communities: one program's success.

The Premedical Honors College (PHC) is an eight-year, BS-MD program created in 1994 by Baylor College of Medicine (BCM) and The University of Texas-Pan American (UT-PA) to increase the number of physicians addressing the health care needs of underserved populations in Texas. The PHC targets South Texas, a 13-county, medically underserved area with a population that is 82% Hispanic. To date, the PHC has had 159 matriculants and 71 graduates, of whom 60 (84.5%) have matriculated into medical school. These results are significant considering that in 1996, only four students from all five South Texas colleges (combined enrollment of 30000 students) were accepted to medical school. An outcomes study comparing PHC matriculants with students of similar academic ability, ethnicity, and interest in medicine revealed that the odds of medical school matriculation were seven times higher for PHC students than for non-PHC students. The PHC's initial success has been acknowledged by the Texas legislature, which recently passed a bill to promote the PHC's replication. In addition, the number of PHC students-of whom 95% are Mexican American-who matriculate into medical school annually is significant nationally. In 2001, only 386 U.S. medical school matriculants (2.3% of all matriculants) were Mexican American; 17 of these students (4.4%) were PHC graduates. If current trends continue, the PHC could significantly expand the number of physicians serving minority and medically underserved populations in Texas and the nation. Also, the PHC provides an opportunity for research on programs designed to create pathways from high school to medical school.     

Zur darstellung tritiummarkierter polymethacrylsäuremethylester

A method is described for the preparation of identical fractions of tritium marked and unmarked fractions of polymethacrylate of higher molecular weights. The labeling is done by TOH on polymethacrylic acid and does not change the molecular weight distribution. Further the influence of labeling by the method of WILZBACH on fractionated polymethacrylate is reported. The molecular weight distributions before and after the exposing to tritium gaz of 3 curie are determined. These data make it is possible to gain information concerning the number of bonds broken and of the position of the active hydrogen atoms in the polymer chain.     

Global gene expression and the role of sigma factors in Neisseria gonorrhoeae in interactions with epithelial cells

Like many bacterial pathogens, Neisseria gonorrhoeae must adapt to environmental changes in order to successfully colonize and proliferate in a new host. Modulation of gene expression in response to environmental signals is an efficient mechanism used by bacteria to achieve this goal. Using DNA microarrays and a tissue culture model for gonococcal infection, we examined global changes in gene expression in N. gonorrhoeae in response to adherence to host cells. Among those genes induced upon adherence to human epithelial cells in culture was rpoH, which encodes a homolog of the heat shock sigma factor, sigma(32) (RpoH), as well as genes of the RpoH regulon, groEL and groES. Attempts to construct an rpoH null mutant in N. gonorrhoeae were unsuccessful, suggesting that RpoH is essential for viability of N. gonorrhoeae. The extracytoplasmic sigma factor, RpoE (sigma(E)), while known to regulate rpoH in other bacteria, was found not to be necessary for the up-regulation of rpoH in gonococci upon adherence to host cells. To examine the role of RpoH in host cell interactions, an N. gonorrhoeae strain conditionally expressing rpoH was constructed. The results of our experiments showed that while induction of rpoH expression is not necessary for adherence of gonococci to epithelial cells, it is important for the subsequent invasion step, as gonococci depleted for rpoH invade cells two- to threefold less efficiently than a wild-type strain. Taken together, these results indicate that sigma(32), but not sigma(E), is important for the response of gonococci in the initial steps of an infection.     

Genomic screen for loci associated with alcohol dependence in Mission Indians.

Alcohol dependence is a leading cause of morbidity and mortality in Native Americans, yet biological factors underlying the disorder in this ethnic group remain elusive. This study's aims were to map susceptibility loci for DSM-III-R alcohol dependence and two narrower alcohol-related phenotypes in Mission Indian families. Each participant gave a blood sample and completed an interview using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) that was used to make alcohol dependence diagnoses and the narrower phenotypes of withdrawal, and drinking severity. Genotypes were determined for a panel 791 microsatellite polymorphisms. Analyses of multipoint variance component LOD scores for the dichotomous DSM-III-R phenotype revealed no peak LOD scores that exceeded 2.0 at any chromosome location. Two chromosomes, 4 and 12, had peak LOD scores that exceeded 2 for the alcohol use severity phenotype and three chromosomes 6, 15, 16 were found to have peaks with LOD scores that exceeded 2 for the withdrawal phenotype. Evidence for linkage to chromosomes 4 and 15, and 16 have been reported previously for alcohol related phenotypes whereas no evidence has as yet been reported for chromosomes 6 and 12. Combined linkage and association analysis suggest that alcohol dehydrogenase 1B gene polymorphisms are partially responsible for the linkage result on chromosome 4 in this population. These results corroborate the importance of several chromosomal regions highlighted in prior segregation studies in alcoholism and further identify new regions of the genome that may be unique to either the restricted phenotypes evaluated or this population of Mission Indians.