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Biomedical subjects

A Hayes

Publications and source records attributed to A Hayes.

161 records · Page 9Linked to original sources
PubMed1976

Some changes in the properties of dynein ATPase in situ and after extraction following heat treatment of cilia.

Glycerol-extracted cilia from Tetrahymena pyriformis were demembranated by treatment with Triton X-100 and then heated for up to 30 min at temperatures between 34-38 degrees C. Heat treatment caused an uncoupling of the ATPase from motility as indicated by an increase in ATPase activity and a loss of pellet height response. After heat treatment, the ATPase activity of the dynein in situ differed from that in unheated cilia as shown by an increased sensitivity to a lower temperature of assay (0 degrees C) and by a loss of the activation normally observed upon reaction with N-ethylmaleimide or p-phenylenedimaleimide. Upon extraction of the heat-treated cilia by Tris-EDTA, there was a large loss in ATPase activity so that the heat-treated cilia yielded a crude dynein fraction with a lower specific activity compared with that obtained from unheated controls. The difference was not due to a change in the amount of protein recovered or in the amount of ATPase activity which remained unextracted. Resolution of the crude dynein by sucrose density sedimentation indicated that activity was lost from both the 14S and 30S peaks but more so from the latter than from the former. Thus dynein in situ in cilia in which the ATPase has been uncoupled from motility by gentle heat treatment differs in several important respects from dynein inside unheated cilia.

Adenosine Triphosphatases↗
PubMed1975

Foot vascular resistance index: a noninvasive method to assess foot vasomotor tone.

A new objective hemodynamic technique has been evaluated to assess foot vasomotor tone pre- and postoperatively in patients undergoing lumbar sympathectomy alone or as an adjunct to vascular reconstructive surgery. A foot vascular resistance index at rest (FVRIR) and after reactive hyperemia (FVRIHT) was determined with a noninvasive plethysmographic method. The ankle-to-toe systolic pressure gradient and foot blood flow were measured with strain gauge plethysmorgraphy and were combined in a ratio to provide an index of vascular resistance. The indices were measured in patients without vascular disease who were used as controls and in patients undergoing lumbar sympathectomy alone or in conjunction with aortic reconstructions. Patients who underwent reconstructive procedures alone had a mean FVRIR which approximated the control value. In contrast, those patients who, in addition, had a lumbar sympathectomy had a significant reduction in the mean postoperative FVRIR which equalled the mean preoperative FVRIHT. Three of five patients undergoing lumbar sympathectomy alone had excellent preoperative hyperemic responses and benefited from the operation, whereas two patients with poor hyperemia had no benefit and had subsequent amputations. Our studies suggest that this technique is of value in the pre- and postoperative assessment of foot vasomotor tone and also may be useful in the preoperative prediction of response to lumbar sympathectomy.

Adult↗
PubMedDate not supplied

Contour integration and cortical processing.

Our understanding of visual processing in general, and contour integration in particular, has undergone great change over the last 10 years. There is now an accumulation of psychophysical and neurophysiological evidence that the outputs of cells with conjoint orientation preference and spatial position are integrated in the process of explication of rudimentary contours. Recent neuroanatomical and neurophysiological results suggest that this process takes place at the cortical level V1. The code for contour integration may be a temporal one in that it may only manifest itself in the latter part of the spike train as a result of feedback and lateral interactions. Here we review some of the properties of contour integration from a psychophysical perspective and we speculate on their underlying neurophysiological substrate.

Action Potentials↗
PubMedDate not supplied

Educating patients after conscious sedation for gastrointestinal procedures.

Medication for conscious sedation during gastrointestinal (GI) diagnostic procedures causes amnesia, thereby preventing patients from recalling postprocedure instructions or follow-up appointments. A serious complication after GI diagnostic procedures is bleeding, which can occur if patients take aspirin or nonsteroidal anti-inflammatory agents after the procedure. Past research revealed that 73% of patients did not remember instructions. The purpose of this randomized controlled trial was: (1) to determine if patients with wrist bands remember to read their postprocedure instructions, and (2) to determine what patient demographics are associated with failure to read postprocedure instructions. Sixty-one GI clinic outpatients participated in this Veterans Affairs Medical Center study, received routine written instructions before and after GI diagnostic procedures, and were randomly assigned to one of two groups: control group (standard care plus next-day phone call) or intervention group (wrist band plus standard care plus next-day phone call). A memory test evaluated patients' knowledge of procedure results, date of follow-up appointment, and medications. Results indicated no significant differences in the memory test between the groups (t = 0.9, p = .36). Patients 65 years of age and older had scores indicating memory problems, regardless of the wrist band (r = 0.19, p = .06). The wrist band was ineffective as a reminder to read instructions; rather, the next-day phone call served as the reminder.

Adult↗
PubMedDate not supplied

Reductions in herpes simplex virus type 2 antibody titers after cognitive behavioral stress management and relationships with neuroendocrine function, relaxation skills, and social support in HIV-positive men.

OBJECTIVE: Coinfection with herpes simplex virus type 2 (HSV-2) is common in individuals infected with human immunodeficiency virus (HIV) and may have health implications. This study examined the effect of a 10-week cognitive behavioral stress management (CBSM) intervention on immunoglobulin G (IgG) antibody titers to HSV-2 in a group of mildly symptomatic HIV-infected gay men and the degree to which these effects were mediated by psychosocial and endocrine changes during the 10-week period. METHODS: Sixty-two HIV+ gay men were randomly assigned to either a 10-week CBSM intervention (N = 41) or a wait-list control condition (N = 21). Anxious mood, social support, cortisol/dehydroepiandrosterone sulfate (DHEA-S) ratio levels, and HSV-2 IgG antibody titers were assessed at baseline and after the 10-week period. CBSM participants also recorded their stress levels before and after at-home relaxation practice. RESULTS: HSV-2 IgG titers were significantly reduced in the CBSM participants but remained unchanged in the control group after the 10-week intervention period. Increases in one type of social support, perceived receipt of guidance, during the 10 weeks was associated with and partially mediated the effect of the intervention on HSV-2 IgG. Similarly, decreases in cortisol/DHEA-S ratio levels were associated with decreases in HSV-2 IgG, and lower mean stress levels achieved after home relaxation practice were associated with greater decreases in HSV-2 IgG among CBSM participants. CONCLUSIONS: These findings suggest that behavioral and psychosocial changes occurring during CBSM interventions, including relaxation, enhanced social support, and adrenal hormone reductions, may help to explain the effects of this form of stress management on immune indices such as HSV-2 antibody titers.

Adaptation, Psychological↗
PubMedDate not supplied

Calvarial hyperostosis syndrome in two bullmastiffs.

Two bullmastiffs with calvarial hyperostosis syndrome are described and are the first documented examples in females. The clinical and radiologic features were similar to those previously reported in males. Magnetic resonance (MR) imaging findings have not previously been reported. One dog underwent MR imaging and abnormalities included thickening of the frontal bones with loss of normal fat signal and changes in the overlying soft tissues. In one of the dogs, long bone changes were seen in the femora and resembled those seen with craniomandibular osteopathy.

Animals↗
PubMedDate not supplied

Pharmacokinetic evaluation of cisplatin in children with malignant solid tumors: a phase II study.

In a phase II trial, cisplatin was given by two randomly assigned dose schedules to 53 children with malignant solid tumors. Both schedules, 30 mg/m2/week and 90 mg/m2 every 3 weeks, were associated with drug-related toxic effects involving the renal, hematopoietic, and neuromuscular systems. Pharmacokinetic studies indicated that the initial serum half-life of total platinum was 27.6 minutes, with a terminal half-life of 44.4 hours. Significant antitumor effect was noted in patients with neuroblastoma and malignant germ cell tumors. Use of cisplatin in combination therapy for patients with these diseases is indicated.

Adolescent↗