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Biomedical subjects

M Stevens

Publications and source records attributed to M Stevens.

At least 181 records · Page 10Linked to original sources
PubMed1986

Mammographic microcalcifications: detection with xerography, screen-film, and digitized film display.

Pulverized bone specks and aluminum oxide specks were measured by hand into sizes ranging from 0.2 mm to 1.0 mm and then arranged in clusters. These clusters were superimposed on a human breast tissue phantom, and xeromammograms and screen-film mammograms of the clusters were made. The screen-film mammograms were digitized using a high-resolution laser scanner and then displayed on cathode ray tube (CRT) monitors. Six radiologists independently counted the microcalcifications on the xeromammograms, the screen-film mammograms, and the digitized-film mammograms. The xeromammograms were examined with a magnifying glass; the screen-film images were examined with a magnifying glass and by hot light; and the digitized-film images were examined by electronic magnification and image processing. The bone speck size that corresponded to a mean 50% detectability level for each technique was as follows: xeromammography, 0.550 mm; digitized film, 0.573 mm; and screen-film, 0.661 mm. We postulate that electronic magnification and image processing with edge enhancement can improve the capability of screen-film mammography to enhance the detection of microcalcifications.

Breast Diseases↗
PubMed1986

The effect of abdominal radiation on spleen function: a study in children with Wilms' tumor.

Reports of splenic dysfunction in patients with Hodgkin's disease who received radiation therapy to the spleen raise questions concerning impairment of splenic function and the long-term risk of bacterial sepsis in children who receive abdominal radiation for other diseases. Splenic function was studied in 20 children with Wilms' tumor using a quantitative assessment of vacuolated ("pitted") red cells as a measure of reticuloendothelial function. Fourteen children had received abdominal radiation to a field involving the spleen at a median dose of 2000 rads. Their pitted red cells counts were no different from those of 6 children who received therapy without radiation to the spleen or to those of a group of normal children and adults. We conclude that there is no demonstrable long-term impairment of spleen function with radiation doses at or below 2200 rads.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

A numerical taxonomic study of Actinobacillus, Pasteurella and Yersinia.

A numerical taxonomic study of strains of Actinobacillus, Pasteurella and Yersinia, with some allied bacteria, showed 23 reasonably distinct groups. These fell into three major areas. Area A contained species of Actinobacillus and Pasteurella: A. suis, A. equuli, A. lignieresii, P. haemolytica biovar A, P. haemolytica biovar T, P. multocida, A. actinomycetemcomitans, 'P. bettii', 'A. seminis', P. ureae and P. aerogenes. Also included in A was a composite group of Pasteurella pneumotropica and P. gallinarum, together with unnamed groups referred to as 'BLG', 'Mair', 'Ross' and 'aer-2'. Area B contained species of Yersinia: Y. enterocolitica, Y. pseudotuberculosis, Y. pestis and a group 'ent-b' similar to Y. enterocolitica. Area C contained non-fermenting strains: Y. philomiragia, Moraxella anatipestifer and a miscellaneous group 'past-b'. There were also a small number of unnamed single strains.

Actinobacillus↗
PubMed1985

Histologic evaluation of new attachment in humans. A preliminary report.

This study was designed to evaluate the potential for regeneration of a new attachment (alveolar bone, cementum and a functional periodontal ligament) in patients whose attachment apparatus had been destroyed by periodontal disease. In each of the three parts of the investigation, the most apical level of calculus on the root served as a histologic reference point to measure regeneration. In Part I, attempts were made to initiate the formation of a new attachment by surgical debridement, crown removal (coronectomy) and submersion of the vital root below the mucosa. Nonsubmerged, surgically debrided defects served as controls. In Part II, debrided intrabony defects were treated with and without demineralized freeze-dried bone allograft and the associated vital roots were submerged. Part III evaluated potential for regeneration of a new attachment in nonsubmerged roots with and without the use of demineralized freeze-dried bone allograft. Gingival grafts were placed over the experimental and control sites in an attempt to retard epithelial migration. Biopsies were obtained in 6 months and regeneration was evaluated histometrically. Preliminary results in 7 patients and 24 intrabony defects indicate that new attachment is possible on pathologically exposed root surfaces in a submerged environment with and without the incorporation of demineralized freeze-dried bone allografts. New attachment was observed on pathologically exposed root surfaces in a nonsubmerged environment when intrabony defects were grafted with demineralized freeze-dried bone allograft. New attachment was not observed on nongrafted, nonsubmerged, defects with and without the placement of gingival grafts over the defects.

Alveolar Process↗
PubMed1984

Breast cancer in mothers given diethylstilbestrol in pregnancy.

We compared the incidence of breast cancer in 3033 women who had taken diethylstilbestrol (DES) in pregnancy during the period from 1940 to 1960 with the incidence in a comparable group of unexposed parous women. We ascertained vital status in 95 per cent of the exposed women and in 93 per cent of the unexposed women and received completed questionnaires for 88 and 85 per cent, respectively. With over 85,000 woman-years of follow-up in each group, the incidence of breast cancer per 100,000 woman-years was 134 in the exposed group and 93 in the unexposed group, yielding a crude relative risk of 1.4 (95 per cent confidence interval, 1.1 to 1.9). The elevated incidence did not appear to be due to bias or to confounding by other risk factors measured in the study. Breast-cancer mortality was slightly higher in the exposed women (relative risk, 1.1) but not significantly so (95 per cent confidence interval, 0.7 to 2.0). We conclude that the incidence of breast cancer is moderately increased in women given DES, but we cannot exclude the possibility that some unrecognized concomitant of DES exposure accounts for this increase.

Actuarial Analysis↗
PubMed1984

Optic neuritis secondary to sinus disease.

Sinus disease is an infrequent, but treatable, cause of optic neuritis. We treated three patients in whom optic neuritis was caused by sinus disease. Treatment of the underlying sinus condition resulted in the improvement of vision.

Child, Preschool↗
PubMed1984

A collaborative evaluation of a rapid automated bacterial identification system: the Autobac IDX.

A collaborative evaluation of the Autobac IDX, a rapid, semi-automated bacterial identification system, was performed in three independent laboratories in three European countries. The system utilises growth inhibition by a series of chemical compounds. Subsequent analysis of the resultant data by quadratic discriminant function automatically results in a bacterial identification. Three sets of 30 strains were examined repeatedly in each of the participating laboratories. The reproducibilities obtained ranged from 85.6% to 96.6%, with an overall average of 91.8%. The accuracy of the system was also determined by examining 1076 isolates from the three participating laboratories. An overall accuracy of 90.3% was calculated by comparing the Autobac result with a reference method. When the results were weighted to represent clinical frequency, the accuracy was 93.6%.

Bacteria↗
PubMed1984

Localized cell death in Drosophila imaginal wing disc epithelium caused by the mutation apterous-blot.

Drosophila melanogaster carrying the mutation apterous-blot have blistered wings. Trypan blue stains a patch of dead cells localized to the wing pouch of imaginal discs and the same area shows acid phosphatase (AcPase) activity suggesting that the cell death is lysosomal. Autophagic vacuoles and other secondary lysosomes show AcPase activity within the disc epithelium and enzyme activity is found in fragments of dead cells which have been extruded basally. The cell death, although extensive and confined to the presumptive wing region, does not result in loss of adult structures.

Animals↗
PubMed1984

Posturography and vestibular compensation.

In unilateral vestibular hypofunction, compensation has to be achieved at the several levels of the balance function. The development of compensation at each level has not necessarily a parallel course. Accordingly, a thorough evaluation of the functional state of the patient, requires a separate assessment for each level. In clinical practice, compensation is evaluated by the testing of provoked vertigo (with eventual positional nystagmus) and by the rotation test results. To these data a measurement of the vestibulospinal level has to be added. Posturography provides this assessment and in this way the global functional state is completed. In many cases the complaints can be objectified and the elaboration of adequate rehabilitation exercises can be founded upon these posturographic data. The detailed analysis of the posturograpohic curves furnishes a diversification of the dysfunctional patterns at this balance level, with also emphasis upon the sensory interaction.

Adaptation, Physiological↗
PubMed1983

Genetic control of rheumatoid factor production in the mouse. Role of genes linked to the immunoglobulin heavy chain locus and to the major histocompatibility complex.

The influence of Igh-1 and H-2 linked genes on the production of IgG2a-specific rheumatoid factors (RF) by 129/Sv mice was examined. Heterozygous animals carrying the 129 alleles, H-2b and Igh-1a, and either H-2k, H-2a, or Igh-1b (but not Igh-1d or Igh-1e) had considerably reduced RF levels. In contrast, Igh-1b linked genes failed to suppress RF production by MRL/MpJ-lpr mice. This lack of suppression was linked to the lymphoproliferation trait characteristic of these animals.

Animals↗
PubMed1983

Integration of schematic faces and other complex objects in schizophrenia.

Twenty-one acute schizophrenic patients and 26 neurotic patients sorted each of six sets of 15 objects into three groups. A set consisted either of schematic faces, nonsense objects, or histoforms, each composed of five independently varying features. For the faces and nonsense objects these features could be integrated into a whole, whereas for the histoforms they could not. The distribution of four of the features was such that a set could be divided into three groups. The fifth feature either remained constant and had no effect on sorting performance or it varied randomly and acted as a distractor. Performance was assessed from the variance in common between the grouping actually present in a set and the grouping produced by the subject. For the control patients faces were sorted much better than histoforms if no distractor was present. However, performance with faces was massively impaired by a distractor while performance with histoforms was not. For the schizophrenic patients faces were not sorted better than histoforms and the effect of distraction was similar for every type of material. The performance of the controls suggest that the gestalt quality of the faces dominated over their constituent details. This enabled more features to be handled at once, thus achieving better sorting with faces than histoforms. However, it also made it more difficult for subjects to ignore a distracting component in the faces. The performance of the schizophrenics suggests that for them the integrated gestalt of the face was not dominant over its components.

Attention↗
PubMed1983

Effects of ECT and depression on various aspects of memory.

Seventy severely depressed patients randomly assigned to receive 8 real or sham ECT were further subdivided on the basis of degree of recovery from depression afterwards. In comparison to a non-depressed control group the depressed patients were impaired on a wide range of tests of memory and concentration prior to treatment, but afterwards performance on most of the tests had improved. Real ECT induced impairments of concentration, short-term memory and learning, but significantly facilitated access to remote memories. At 6 months follow-up all differences between real and sham ECT groups had disappeared. On the majority of tests the previously depressed patients now performed at the same level as the control group. There was some evidence that a subgroup of treatment-resistant patients (poor outcome after real ECT) were significantly more likely to complain of memory problems 6 months later.

Adult↗