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Biomedical subjects

H Koller

Publications and source records attributed to H Koller.

At least 19 recordsLinked to original sources
PubMed1992

27Al and 23Na double-rotation NMR of sodalites.

The 27Al NMR spectra of calcium tungstate aluminate sodalite (CAW), Ca8[Al12O24](WO4)2, and the 23Na NMR spectra of sodium aluminosilicate sodalites of general composition Na9[Si6Al6O24]A2 with A = B(OH)4- (SBS), SCN- (SRS) and A2 = SO4(2-) (SSS), MoO4(2-) (SMS) have been measured using magic-angle spinning (MAS) and double-rotation (DOR) techniques. Rotor synchronized pulse excitation is applied in the DOR experiments. Dramatic line narrowing is observed in the DOR spectra of all samples. The 27Al DOR NMR spectra of CAW measured at 9.4 and 11.7 T and spinning rates of 800-1150 Hz of the outer and 5 kHz of the inner rotor show seven sharp central lines accompanied by a manifold of spinning sidebands. These lines correspond to the seven crystallographically inequivalent Al sites of the CAW framework derived from X-ray structure analysis. From the difference of the line positions in the 9.4 and 11.7 T spectra the quadrupole coupling constant, QCC, quadrupole induced shift, sigma qs, and isotropic chemical shift, delta cs, of each Al site have been calculated. QCC values in the range of 5 to 9 MHz are obtained which reflect the strong tetragonal distortion of the AlO4 tetrahedra in CAW. delta cs shows only small changes in the range between 74.4 and 77.2 ppm. A tentative assignment of all lines to the distinct Al sites is derived from the correlation between QCC and a "shear strain parameter" describing quantitatively the distortion of the AlO4 tetrahedra.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1992

Families of children with mental retardation: comprehensive view from an epidemiologic perspective.

Data covering a 15-year period on the health, behavior, and functioning of a representative population of families of children with mental retardation and comparison children were used in cluster analysis to obtain relatively homogeneous groupings of families. Only a small minority of families of children with mental retardation did not cluster together with comparison families. More than a third functioned well and had a middle-class orientation; less than a third functioned poorly. A few clusters had ambiguous configurations, but most were easily understood and conformed generally to expectations in validation analyses.

Adaptation, Psychological↗
PubMed1991

[Experiences with PTCA at the Klagenfurt Regional Hospital].

From October 1986 to July 31th 1990 343 patients had coronary dilatations (PTCA) at the Landeskrankenhaus Klagenfurt. In total 380 stenoses in the coronary vessels were dilated. In 83% of stenoses "complete revascularization" was obtained. Success rate was 90%.

Adult↗
PubMed1990

Uptake and metabolism of retinoic acid induces inhibition of cell growth: a study in a rat rhabdomyosarcoma cell line (BA-HAN-1C) using nonlinear theoretical models.

Retinoic acid causes a significant inhibition of cell growth of the tumor cell line BA-HAN-1C. This growth inhibition is the same whether the cells are treated with a pulse dose of retinoic acid (RA) or continuously expand to RA. The determination of RA and its degradation products within the culture medium and in the cells showed that after 24 hours 13-cis-RA was the major retinoid in all cells (96 ng/10(6) cells); all-trans-RA represented 56 ng/10(6) cells. After 48 hours 4-hydroxy-RA and a small amount of 5,6-epoxy-RA was found in the cells and also in the culture medium. 4-hydroxy-RA increased up to 96 hours, whereas 13-cis- and all-trans-RA were not detectable in the cells after 96 hours. We conclude that the BA-HAN-1C cells take up and metabolize RA. Nonlinear fit analysis of the time behavior of the RA concentration in medium demonstrates that the RA uptake unexpectedly follows a mono-exponential time function. Discussion of the experimental results in connection with a proper compartment model shows that uptake and metabolism of RA cannot be described really by a first order kinetics. The mathematical analysis leads to a more complicated kinetic model with certain restrictions for the corresponding rate constants.

Animals↗
PubMed1989

[The heart catheter protocol--understandable and informative].

Coronary heart disease has the highest incidence in our society. Practising physicians are often confronted with a lot of data obtained from invasive investigations (heart-catheterization and angiocardiography). The interpretation of cardiologic parameters and their measurements cause difficulties for physicians who are not permanently involved in this matter. It is the aim for this paper to present a logically conclusive protocol and to explain cardiologic catheter-parameters in use and their meaning.

Cardiac Catheterization↗
PubMed1989

[Contaminating substances in 22 over-the-counter fish oil and cod liver oil preparations: cholesterol, heavy metals and vitamin A].

Fish oil capsules are increasingly used by self-medicating patients. We studied 22 commercial fish oil and menhaden oil preparations in respect to accompanying substances that could be harmful. The substances measured were: cholesterol as determined by gas liquid chromatography, heavy metals measured by atomic absorption, and vitamin A as determined by high-performance liquid chromatography (HPLC). The contents of cholesterol and heavy metals were in ranges which can be regarded as negligible; the content of vitamin A in menhaden oils, however, was found in amounts which warrant that pregnant women do not exceed the dosage as recommended by the manufacturers.

Animals↗
PubMed1988

[Angina pectoris].

Coronary heart disease has many different clinical courses: it can cause rhythm-disturbances, sudden death, pump-failure, no pain at all (silent ischemia) or typical angina. Heart-pain can occur "on demand" after physical or mental stress with a duration of 3 to 5 minutes with typical location and good response to nitrates. It also can cause atypical forms of angina such as angina on rest, mostly due to coronary spasms. Angina can stable over months and years but can suddenly increase in severity and duration. This form is called unstable angina, which has to be recognized as soon as possible since acute myocardial infarctions evolve rather frequently. Infarction is an irreversible myocardial damage but before it develops many measures can be taken to preserve the jeopardized myocardium. The recognition and differentiation of angina pectoris is therefore of utmost importance.

Angina Pectoris↗
PubMed1988

Marriage in a young adult mentally retarded population.

Marriage was examined in a total population of mentally retarded young adults born in a 5-year period. No one with severe retardation had married. Among the mildly retarded, significantly fewer young people had married by age 22 than in a nonretarded comparison population, and the retarded young people who had married had significantly higher IQs than the remainder of the mildly retarded population. The retarded females had significantly more problems in their marriages than nonretarded comparisons. Nevertheless, the marriages of almost half the mildly retarded young women appeared to be working out well. The retarded young men were not significantly different from nonretarded comparisons. Marriages in which both partners were retarded had many problems.

Adult↗
PubMed1988

Peer relationships of mildly retarded young adults living in the community.

Socializing with peers and opposite-sex relationships were examined in two subsets of a mildly mentally retarded (MMR) young adult population living in the community: those who were no longer receiving MR services and those who were attending day centres for MR adults. The MMR young people not receiving services had fewer best friends and socialized significantly less often than a nonretarded comparison population. The MMR males not receiving services also had fewer opposite-sex relationships than comparisons but this difference was not significant for the females. At age 22, these MMR young people continued to see friends from school significantly less often than comparisons, indicating a possible detrimental effect of special schooling on later socializing with peers. The MMR young people at the day centres socialized more often but this was done almost wholly with others who were MR. Within the MMR study population, the young women not receiving services socialized with peers the least, less than the young women at the day centres and less than the young men not receiving services, but they were married most often.

Adult↗
PubMed1988

Job histories in open employment of a population of young adults with mental retardation: I.

Job histories were obtained for a population of young adults with mental retardation. No one with IQ less than 50 had been in open employment. Persons with mild mental retardation (n = 100) who received no adult services were compared to peers who were not retarded (n = 52) who left school without academic qualifications on a variety of job measures (e.g., unemployment, time out of the labor force, job turnover, level of job skill, and take-home pay). Among the 54 subjects with IQs of 50 or more who received adult services, approximately half had some open employment. Our results provide a less optimistic picture than that given by reviewers of previous research.

Adult↗
PubMed1987

Sex differences in the classification of children as mildly mentally retarded.

A consistent finding in epidemiological studies of mild mental retardation (MMR) is a somewhat higher prevalence of boys than girls. Our own study in Aberdeen agreed with these findings. Examination of the numbers of boys and girls at different levels of retardation within our study population revealed the greatest excess at the highest IQ levels of greater than or equal to 75. This was found to be true in other studies as well. Since this IQ range is above the generally agreed upon cut-off point used to classify children as MMR, these findings suggest that boys remaining in regular classes may be having more difficulty in school performance than girls. Possible reasons for this are examined.

Adolescent↗
PubMed1987

Antecedents of behavior disturbance in mildly mentally retarded young adults.

Behavior disturbance was found to be more frequent among mildly retarded (MMR) than a group of young adults matched during childhood for age, sex and social class. Reasons for this were examined. An unstable environment in childhood was found to be significantly related to behavior disturbance in both MMR and controls. The greater frequency of behavior disturbance among the MMR was due to their more frequently experiencing unstable environments in childhood than comparisons. Further, when stability of upbringing was held constant, differences in behaviour disturbance between the two groups were no longer found. Central nervous system damage was found not to be a contributory factor.

Adolescent↗
PubMed1986

Factors leading to differences in the school performance of boys and girls.

Literature supporting the finding that boys do not fare as well in school performance during the first few years of school is reviewed, and possible reasons for this pattern are presented. These reasons are categorized as biological (e.g., X-linkage of intellectual traits) and social (e.g., sex-role training is more stringent for boys than for girls, and parents may place more pressure on boys for academic achievement). Social factors are presented in light of the rapid social change that has been taking place in the carrying out of adult sex roles and whether this has filtered down to changes in the sex-role training in the socialization of children. Pediatricians should be aware of whether school problems are occurring for both boys and girls, and their responses to such problems may differ, depending on the child's sex.

Achievement↗
PubMed1986

A longitudinal study of numbers of males and females in mental retardation services by age, IQ and placement.

A year-by-year analysis up to age 22 was carried out of the numbers of males and females in a birth cohort receiving mental retardation services in a British city. A slight excess of males was found during childhood, with the largest excess occurring at the upper end of the IQ range, the borderline area for classifying children as mentally retarded. There was also a large male excess found in residential care at each age. During the young adult years, this predominance of males in residential care was offset by an excess of females attending day care centres, leading to almost equality of numbers of males and females receiving some sort of services during this period. Possible explanations for the findings were discussed.

Adolescent↗
PubMed1986

Sex differences in number of children administratively classified as mildly mentally retarded: an epidemiological review.

Many epidemiological studies of mental retardation have shown a higher prevalence of boys than girls. Data were reviewed from various studies consistently showing that the highest male/female ratios are found at the upper end of the IQ range for children classified as mentally retarded. One reason for this may be that boys with IQs at the upper end of this range have greater difficulty than girls in meeting the requirements of school performance. Factors that may cause boys to experience more difficulties than girls in the early school years were reviewed.

Child Development↗