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Biomedical subjects

L Stevens

Publications and source records attributed to L Stevens.

At least 163 records · Page 9Linked to original sources
PubMed1984

Surgical procedures in nonagenarians.

During the hospital course of 225 nonagenarian patients who underwent 285 major operations-80% on the general, vascular, orthopedic and urologic services-overall morbidity was 37% and mortality 7.5%. The 100 emergency operations were associated with a higher morbidity and mortality rate. Nonsurvivors were more likely to have associated cardiac or cerebral medical conditions, higher utilization of intraoperative invasive hemodynamic monitoring and greater use of surgical intensive care units. Compared with all surgical patients, the nonagenarians were admitted twice as often to the surgical intensive care unit, required twice the number of hospital days, underwent intraoperative hemodynamic monitoring twice as frequently and incurred 200% greater hospital charges. We conclude that with careful evaluation and management, a nonagenarian patient presenting with a surgical condition can safely undergo necessary operative procedures.

Aged↗
PubMed1983

Detection of a proteinase inhibitor in Aspergillus nidulans.

The activity of proteinases in mycelial extracts of Aspergillus nidulans increased during storage. The rate of activation increased with temperature. Three separate proteinase activities, differing in their electrophoretic mobilities on polyacrylamide gels, were readily detected at pH 6.5. Inhibitory activity, effective against all three proteinase activities, was also detected in fractions prepared from fresh mycelial extracts. The inhibitory factor(s) were heat-stable and non-dialysable. The inhibitory activity was lost during storage of mycelial extracts. It is proposed that the inhibitory factor(s) are digested by the proteinases during storage.

Aspergillus nidulans↗
PubMed1983

Purification and properties of two neutral proteinases from Aspergillus nidulans.

Two proteinases have been purified from mycelial extracts of Aspergillus nidulans. Both enzymes have pH optima between 6.5 and 7.5 and are inhibited by phenylmethane sulphonyl fluoride and by di-isopropyl fluorophosphate. The molecular weights and isoelectric points of proteinase I and proteinase II are 30 900 and 30 000, and 4.6 and 4.3, respectively. Both enzymes have a similar range of substrate specificities. The principal differences in their properties are that proteinase I is sensitive to inhibition by 1 mM mercurials whereas proteinase II is not appreciably inhibited at this concentration, and that proteinase I is much more sensitive to denaturation by urea, guanidine hydrochloride and sodium dodecyl sulphate.

Aspergillus nidulans↗
PubMed1983

Paced abdominal breathing and EMG responsivity.

5 subjects participated in a within-subjects design to determine the effect of paced abdominal breathing on EMG levels. After training in thoracic and abdominal breathing, each subject's respiration performance and EMG levels were assessed in both breathing modes via a counterbalanced A-B-A-B reversal design. Reliable effects of respiration training were observed in both breathing modes. No effects were observed on EMG measures. The results were discussed in relation to literature on approaches to respiration training which may target specific arousal indices other than electromyogram activity. The utility of dovetailing complementary treatment techniques such as respiration training and relaxation training which are specific to particular arousal indices was discussed.

Abdomen↗
PubMed1983

Puppetry and doll play as an adjunct to pediatric orthopaedics.

The loss of a considerable segment of body tissue is often psychologically more traumatic than is the actual surgery to the unprepared child. In an attempt to improve the preparation of the child for ablative surgery, as well as to facilitate the pre- and postoperative management of the pediatric patient and family, we have developed a system of doll play and puppetry to educate and prepare children for this type of surgery. Guilt feelings are minimized, an outlet for hostility is provided, and the ever present fear of the unknown is confronted and dealt with in a manner acceptable to the child. The nonthreatening role of this technique also helps alleviate parental fears and concerns. Our experience with this technique has confirmed its usefulness in the preoperative psychological preparation of young children facing amputation or major musculoskeletal procedures.

Body Image↗
PubMed1982

Diatomite as a source of cristobalite for dental investments a differential thermal analysis study.

Cristobalite can be obtained from diatomite by heat-treatment at relatively low temperatures and short times without the use of flux. The differential thermal analysis method used to examine the alpha leads to beta inversion was not as satisfactory as it might have been, and to determine the amount and crystallinity of cristobalite formed any such method should be supported by other techniques, in particular, X-ray diffraction. To determine the suitability or otherwise of cristobalite produced from diatomite for use in dental investments, dialatometric studies are indicated since the property of thermal expansion is of fundamental importance to a dental investment.

Chemical Phenomena↗
PubMed1981

RNA synthesis during the germination of conidia of Aspergillus nidulans.

RNA accumulates most rapidly in germinating conidia of Aspergillus nidulans between 6 h and 14 h after the initiation of germination. 3H-adenine is incorporated into all classes of RNA before the emergence of the germ tube, but most of the label appears in rRNA. There is an increase in total RNA polymerase activity, which occurs in parallel with the increase in RNA synthesis. Three peaks of RNA polymerase activity were separated on phosphocellulose columns and their properties investigated.

Aspergillus nidulans↗
PubMed1980

Studies on local immunity to sperm-dissolving of cervical mucus by use of bromelin with retention of antibody activity.

The complete dissolving of human cervical mucus was achieved with bromelin. The adequacy and the mildness of this procedure were studied by making both solutions and simple extracts of a number of mucus samples. Both types of preparation were tested for sperm antibody by our methods of agglutination and immobilization. The comparisons showed a high degree of concurrence between these two types, with the bromelin solutions showing positive results more often than the extracts. Other control tests showed that addition of bromelin did not perturb the antibody testing of positive and negative sera. We concluded that addition of bromelin, in a 1/3 volume, gives a quick, thorough and undamaged solution of cervical mucus, on which sperm antibody tests can be done with ease and reliability.

Antibodies↗
PubMed1980

Some properties of a stir-cast Ni-Cr based dental alloy.

A Ni-Cr based crown and bridge alloy has been successfully stir-cast into small investment mould spaces using a modified induction melting and casting machine. Stir-casting produced substantial improvements to the mechanical properties of the cast alloy. A model for the development of the stir-cast microstructure is described and the clinical significance of the improvements in the alloy's properties is discussed.

Chemical Phenomena↗