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Biomedical subjects

S Adam

Publications and source records attributed to S Adam.

At least 73 records · Page 4Linked to original sources
PubMed1992

Predictive testing for Huntington disease in Canada: adverse effects and unexpected results in those receiving a decreased risk.

By January 1, 1991, a total of 388 persons had enrolled in the Canadian collaborative study of predictive testing for Huntington disease (HD). Of these participants, 105 persons have been given a decreased risk result. Contrary to expectations, approximately 10% of persons with a decreased risk result have had psychological difficulties coping with their new status. Here, we describe the individual responses of 6 such persons and experimental themes emerging after following these persons for up to 2 years. Individuals who are more likely to suffer an adverse reaction to a decreased risk result include those persons who have made irreversible decisions based on the belief they would develop HD or those who had unrealistic overoptimistic expectations of the positive effects of a decreased risk result. In contrast to those receiving an increased risk result, the most vulnerable time for persons receiving a decreased risk result is between 2 and 12 months after learning the outcome. The need for assessment and counselling of participants in predictive testing programs, even when there is a decreased risk result, is emphasized.

Adult↗
PubMed1992

Breaking into prisons.

Explore the source record for details and available documents.

Health Services Administration↗
PubMed1992

Humoral responses to type I collagen after surgical curettage procedures employing bovine collagen implants.

Freeze-dried bovine type I collagen was implanted into periodontally diseased sites of 11 patients in an effort to repair the affected site. Peripheral blood samples taken at 0, 6 and 12 wk were assayed for antibody to human and bovine collagen using an enzyme-linked immunosorbent assay and compared with samples from 9 control subjects. Antibody levels to both human and bovine collagen, which were present at significantly higher levels in the patients at 0 wk than in the control subjects (P less than 0.01 for human and bovine), were significantly lower at 6 wk than at zero time (P less than 0.05 and P less than 0.01 for human and bovine collagens, respectively). At 12 wk post-implantation, the antibody level to human collagen still remained significantly lower (P less than 0.05) than zero time levels but not in respect of the antibody to bovine collagen.

Adult↗
PubMed1992

How should Fitts' Law be applied to human-computer interaction?

The paper challenges the notion that any Fitts' Law model can be applied generally to human-computer interaction, and proposes instead that applying Fitts' Law requires knowledge of the users' sequence of movements, direction of movement, and typical movement amplitudes as well as target sizes. Two experiments examined a text selection task with sequences of controlled movements (point-click and point-drag). For the point-click sequence, a Fitts' Law model that used the diagonal across the text object in the direction of pointing (rather than the horizontal extent of the text object) as the target size provided the best fit for the pointing time data, whereas for the point-drag sequence, a Fitts' Law model that used the vertical size of the text object as the target size gave the best fit. Dragging times were fitted well by Fitts' Law models that used either the vertical or horizontal size of the terminal character in the text object. Additional results of note were that pointing in the point-click sequence was consistently faster than in the point-drag sequence, and that pointing in either sequence was consistently faster than dragging. The discussion centres around the need to define task characteristics before applying Fitts' Law to an interface design or analysis, analyses of pointing and of dragging, and implications for interface design.

Data Display↗
PubMed1991

A new class of potent antiproliferative glycolipids.

The synthesis and biological activities of a new class of antiproliferative glycolipids with an unexpected broad spectrum of activity, including a human multidrug resistant cell line, are described. Chemically these compounds are glycolipids derived from N-acetyl-D-glucosamine and glycyrrhetinic acid (beta-aglycone). Peptidation of the glucoacids allyl 3 beta-[[2-acetamido-3-O-[(R)-1-carboxyethyl]- 2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranosyl]oxy]-11-oxo-12- oleanen-30-oate and (R,S)-2-methoxy-3-(octadecyloxy)propyl-2-acetamido-3-O-[(R)-1-carb oxyethyl]- 2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranoside was successfully achieved after activation with O-benzotriazolyl-N,N,N',N' -tetramethyluronium hexafluorophosphate.

Acetylglucosamine↗
PubMed1991

Linkage disequilibrium and modification of risk for Huntington disease.

The major limitation in performing predictive testing for Huntington disease (HD) is the unavailability of DNA from crucial family members. In our program approximately 20% (36/183) of persons have been excluded from predictive testing because of this reason. The major aim of this study was to examine whether data derived from linkage disequilibrium could modify risk analysis for persons at risk for HD. As a first step, we assessed whether the previously reported linkage disequilibrium between alleles recognized by probe pBS674E-D at locus D4S95 remained significant in a much larger data set. A total of 1,150 chromosomes from 622 individuals--200 affected and 422 unaffected--from 118 families were assessed. Significant haplotype association was detected with AccI and MboI RFLPs at the locus D4S95, with all the families (P = .00003), as well as for a subset from the United Kingdom (P = .0037). Data derived from linkage disequilibrium studies using D4S95 modifies the risk for HD, especially in persons of U.K. descent. Utilization of this approach for risk modification of HD awaits both validation of these data and additional information concerning ethnic-specific alleles at the D4S95 locus.

Adult↗
PubMed1989

Community attitudes to cystic fibrosis carrier testing in England: a pilot study.

Inexpensive and accurate carrier testing for cystic fibrosis (CF) will be possible in the near future. There are no existing studies on the attitudes of English persons in the community to carrier testing for CF or any other recessive disorder. We have conducted a trial study of 166 persons at two schools, two doctors' surgeries, and a family planning clinic. Only a minority had clear pre-existing knowledge of cystic fibrosis and its genetic nature. However, over 80 per cent of those questioned expressed interest in knowing their carrier status. Although it is well known that uptake can only be assessed when a service is in place, and while further studies are required to confirm that testing will be of interest to couples of reproductive age with no previous knowledge of CF, the data strongly suggest that there will be interest in community-wide testing for CF carrier status when such a test becomes available in the United Kingdom.

Attitude to Health↗
PubMed1989

Use of a laser diffraction particle sizer for the measurement of mean diameter of multicellular tumor spheroids.

Increasing use is being made of tumor cell lines cultured as cell aggregates (generally referred to as multicellular spheroids) in in vitro radiosensitivity and/or chemosensitivity tests. Conventional procedures for the determination of mean spheroid diameters for the construction of growth delay curves employ a microscope-image analyzer. However, this approach can prove excessively time consuming when large numbers of samples have to be measured. We have, therefore, been exploring the use of a Laser Diffraction Particle Sizer, the Malvern 2600 long bench model, for the measurement of mean spheroid diameter and size distribution. We report here a direct comparison between measurements carried out by the instrument and under the microscope. Also a comparison of growth curves for six cell lines constructed from measurements by the microscope and by the instrument. A number of factors that might affect the accuracy of spheroid diameter measurement by the instrument have been investigated: The effect of stirring to maintain the spheroids in suspension during measurement. Sampling error due to removal of a series of spheroid samples from culture flasks for measurement. Optimum numbers of scans to be carried out by the instrument to reach a constant value for mean diameter, and minimum SE of the mean.

Animals↗
PubMed1988

Conformational flexibility in the right-handed and in the left-handed double helices of Na+-d(m5C-G-T-A-m5C-G) studied by IR spectroscopy.

The X ray diffraction study of a d(m5C-G-A-T-m5C-G) crystals has shown the existence of a 2 conformation while the Raman spectroscopy study of the same fragment in solution showed that then the oligonucleotide adopted a B geometry. Infrared spectroscopy has allowed us to study this sequence in films in a wide range of hydrations and to vary the water content of the sample at different rates. We have thus obtained four I.R. spectra, of the B and 2 conformations respectively at 100% and 98% relative humidities, of another 2 form with a different geometry of the phosphate groups at relative humidities below 98% and in addition a fourth spectrum recorded after a rapid dehydration of the sample which is then blocked in a right-handed form at low R.H. In this case the structure of the phosphodiester chain may be not uniform. The results are discussed by comparison with previously obtained I.R. spectra of poly d(G-C), poly d(A-C). d(G-T), d'm5C-G-A-m5C-G-T-G-C-G) d(m5C-G-C-G-m5C-G) and d(C-G-m5C-G).

DNA↗
PubMed1988

[Nuclear medicine diagnosis of Alzheimer type dementia].

Eleven patients with Alzheimer type dementia were investigated by single-photon-emission computed tomography (SPECT) using 99mTc-hexamethylpropylene-aminoxim (HM-PAO). Nine had a typical, symmetrically reduced enrichment in the parieto-temporo-occipital area. In three of these nine patients a similar pattern was recorded additionally in the frontal, in the remaining two in the temporal or parietal region. In a semi-quantitative evaluation radioactivity concentrations in the cerebrum and cerebellum were compared. It demonstrated that there was in relation to the cerebellum a reduced concentration in seven of the eight studied cerebral regions. The relative blood flow of the parieto-temporo-occipital region was most markedly affected and in patients with Alzheimer type dementia was reduced by 25% below that of normal subjects. The results indicate that cerebral SPECT with HM-PAO is a reasonable method of investigation to confirm the diagnosis of "Alzheimer type dementia" and exclude other cerebral disease, especially if pathognomonic findings are to be obtained.

Alzheimer Disease↗
PubMed1988

IR and UV studies on stability and conformations of short DNA duplexes containing a no-base residue: coexistence of B and Z conformations.

Tridecamers containing a central no-base residue (X) have been synthesized and hybridized to their complementary strands, so as to constitute duplexes consisting of two hexamers separated by central mismatched X-A or X-T pairs. The effect of the introduction of this deoxyribose derivative on duplex stability was investigated by measuring UV absorbance as a function of salt concentration and temperature. As expected, the duplexes containing the abnormal base pairs (X-T and X-A) are less stable when compared to the totally complementary duplexes (A-T and T-A). The X-T mismatched duplex shows the most unstable thermodynamical behaviour. The conformational changes of these duplexes were studied by IR spectroscopy in condensed phase as a function of water content. At high relative humidity, the IR spectra show that these tridecamers form B-type double stranded duplex structures. If the water content is decreased, only the duplexes m5CGm5CGCTXAGCTTC GCGCGAATCGAAG and, to a lesser degree, m5CGm5CGCTXAGCTTC GCGGCATTCGAAG undergo a partial B---Z transition involving the methylated hexamer, the conformation of the second segment remaining of the B type. These results show that only one apurinic residue leads to a flexible junction between B and Z forms in a short duplex containing 5-methyl-2'-deoxycytidines.

Base Composition↗