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Biomedical subjects

D Myers

Publications and source records attributed to D Myers.

At least 73 records · Page 4Linked to original sources
PubMed1986

Primary and adjunctive intra-arterial digital subtraction arteriography of the lower extremities.

Standard contrast arteriography (SCA) and intra-arterial digital subtraction arteriography (DSA) were performed during a 26-month period in 459 cases. The DSA group consisted of 22 aortoiliac studies, 66 crural-pedal arch studies, and 227 combinations. In addition, postoperative DSA was performed in 42 patients to evaluate graft patency, morphology, and inflow and runoff circulations. There were no significant differences in the quality of the preoperative aortoiliac studies performed by either SCA or DSA although, in select cases, one or the other of these techniques resulted in a superior study. Distal crural-pedal arch visualization was enhanced with DSA compared with SCA (85% vs. 65%) but when both were compared with their corresponding intraoperative completion arteriograms, the interpretive error rates resulted in comparable accuracies, false positive and negative rates, and predictive values. The likelihood of achieving graft patency in patients who have unsatisfactory preoperative visualization of the distal circulation by DSA is reasonable (11 of 27 patients) but inferior to the number obtained when there is adequate DSA visualization (40 of 53 patients). We conclude that DSA is a valuable adjunct to preoperative SCA but should not be used as the sole criterion for the assessment of operability for limb salvage. Intraoperative prereconstruction arteriography or direct surgical exploration of the crural arteries in patients with inadequate preoperative visualization will result in graft patency in a significant percentage of cases. Intra-arterial DSA for postoperative evaluation of lower limb bypass adds another dimension to analysis of graft structure and status of the host circulatory beds and also provides a method for accurate interpretation of postoperative data.

Angiography↗
PubMed1986

Dynamics of infant feeding: mothers, professionals, and the institutional context in a large urban hospital.

A multidimensional approach was taken to understand the constraints to breast-feeding in a large municipal hospital. Data were collected through direct observation, chart review, and questionnaires to patients and staff. Breast-feeding had not yet begun within 24 hours postpartum in 37% of women who wanted to breast-feed. Chart review revealed that at hospital discharge no woman was breast-feeding exclusively: only 16% of infants had ever been breast-fed and all of these also had been formula fed. The most common reason for the use of supplementary formula and early weaning was the mother's perception or anticipation of insufficient milk. The existing procedures communicated the message to patients that the health care providers expected women to bottle-feed. Some practices that prevented successful breast-feeding were prolonged and/or unnecessary separation of mother and infant, routine provision of infant formula, confusion about drug contraindications for breast-feeding, and inconsistent identification of breast-feeding infants. Staff knowledge about breast-feeding management was inadequate, and staff underestimated mothers' interest in breast-feeding. Recommendations to facilitate breast-feeding include a revision of routines and procedures as well as provision of staff education and expansion of patient education.

Adolescent↗
PubMed1985

Magnetic circular dichroism studies on the heme and tryptophan components of cytochrome c peroxidase.

We have measured the magnetic circular dichroism of cytochrome c peroxidase and some of its derivatives from 250-350 nm. Comparison of the changes observed on conversion to the catalytic intermediate (cytochrome c peroxidase-I) with spectra obtained from horseradish peroxidase and its derivatives and model compounds of protoheme leads us to the conclusion that the observed changes in the magnetic circular dichroism spectra reflect conversion of the heme to the ferryl state. No evidence was found for modification of tryptophan in cytochrome c peroxidase-I.

Cyanides↗
PubMed1985

Microcomputer tools for steady-state enzyme kinetics.

Three programs useful for the investigation of steady-state kinetics have been developed. Two provide the solution to the steady-state rate equation; the first of these is a straightforward implementation of the rules developed by Chou. The second is a very efficient procedure for evaluating King-Altman diagrams and can be used for quite large mechanisms. The third program provides the numeric solution for a specific mechanism and set of initial conditions; it is well suited to extremely large models.

Algorithms↗
PubMed1983

Cerebral cortical extracellular fluid H+ and K+ activities during hypotension in cats.

Cerebral cortical blood flow, electrical activity, and extracellular fluid (ECF) pH and K+ ion activities were measured in anesthetized cats (0.7% halothane 65% N2O in O2) subjected to hypotension (mean BP 30-32 and 26-28 mmHg), induced by either practolol and trimetaphan (TMP) or practolol and nitroprusside (NTP). Limited blood withdrawal was also necessary to achieve these blood pressure (BP) levels. Cerebral cortical blood flow during hypotension was greater with NTP than with TMP, and hyperemia occurred in the recovery phase after NTP but not TMP. Electrical activity also was maintained better with NTP. ECF K+ increased in five of six TMP experiments but in only one of six NTP experiments. Values of K+ greater than 15 mM were only seen in the TMP group. Release of K+ into the ECF space occurred at values of cerebral cortical oxygen delivery below 3 ml 100 g-1 min-1. ECF K+ partially recovered after the end of hypotension in all except the experiment with the highest value. A progressive and severe cerebral acidosis was seen in all experiments during induced hypotension, and values below pH 6.50 were present at the stage of K+ increase in the ECF space. It is concluded that the ability of cell membranes in the cat's cortex to maintain normal ionic gradients is depressed by hypotension to these levels with TMP, but not with NTP, and that this difference is related to better-maintained oxygen supply values during NTP hypotension.

Animals↗
PubMed1980

Humoral immunologic responses in idiopathic juvenile periodontitis (periodontosis).

Humoral responses were examined in idiopathic juvenile periodontitis (IJP) including antibody titers to representative strains of the five groups of periodontosis-associated bacteria. Titers as determined by indirect immunofluorescence were compared in IJP, non-IJP family members, periodontitis and periodontally healthy subjects. Serum concentrations of IgG, IgA, IgM and IgE were also assayed. Antibody titers to the periodontosis-associated bacteria were generally low. Some disease specificity was observed in that titers to Groups II and III bacteria were highest in IJP. These titers in IJP were significantly higher (P less than 0.01) than in the other subjects. Titers to Group I bacteria were similar in all periodontal groups except the periodontally healthy subjects where titers were the lowest. Titers to Group I bacteria were significantly higher (P less than 0.01) than in the periodontally healthy subjects. Titers to Groups IV and V were uniformly low in all periodontal groups. Immunoglobulin concentrations of IgA, IgM and IGE were similar in IJP and non-IJP. The IgG concentrations in IJP, while within the normal range were significantly higher in IJP compared to non-IJP family members.

Adolescent↗
PubMed1978

Impediments to the course and effectiveness of discharge planning.

This paper examines the proposition that "timing" (of referral) is a crucial element in determining the effectiveness of the discharge planning process. A brief review of the relevant literature is followed by the description of a study undertaken to assess the impact that various impediments had upon discharge planning practice in two matched ward populations of a large, acute care university hospital. Along with timing, three other impediments were identified and their influence assessed; (a) noncompletion of transfer forms required; (b) unavailability of an appropriate (i.e., needed level of care) bed in an approved facility; and(c) unanticipated change in the patient's medical condition. Some implications of the findings are examined and discussed, and directions for future study are identified. Appended are facsimiles of the instruments employed.

Hospital Departments↗