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Biomedical subjects

A H Morris

Publications and source records attributed to A H Morris.

At least 73 records · Page 4Linked to original sources
PubMed1989

Oregon's Patrick case and Supreme Court decision.

Does the Patrick decision affect properly done peer review used to consider quality patient care? The answer is most definitely no! If guidelines are followed that abide by the HCQIA and hospital peers review bylaws, then one can be fairly certain that physician reviewers are, indeed, immune to most liability challenges (one should remember, however, that compliance with HCQIA only provides immunity from federal and state law private claims, and not actions by the U.S. Department of Justice as a State Attorney General, i.e. criminal antitrust claims). We must be aware of and revise where necessary to conform to HCQIA our own hospital medical staff bylaws and policies as well as state procedural and reporting policies. We have learned that anticompetitive acts in the business of medicine are dealt with under the law no differently than anticompetitive acts in any other business. We must be aware of antitrust laws and remember as an extension of Patrick that medical groups dealing with alternative health delivery systems and joint ventures must consider any anticompetitive aspects of proposed contracts. Failure to do so could put us in jail.

Humans↗
PubMed1989

Increased insulin-like growth factor I binding to red blood cells of normal prepubertal children.

Young children are growing at a time when circulating levels of IGF-I measured by RIA are generally less than or equal to values in nongrowing adults. 125I-Thr59-IGF-I binding to receptors on conveniently available red blood cells was studied in 33 normal adults (nine males, 24 females) and 13 normal prepubertal children aged 3-10 y (10 boys, three girls; all Tanner stage 1). Red blood cell specific binding of 125I-Thr59-IGF-I was determined by displacement of labeled Thr59-IGF-I by unlabeled Thr59-IGF-I or insulin in a dose-dependent manner. Mean (+/- SEM) 125I-Thr59-IGF-I specific binding was significantly higher (p = 0.01) in prepubertal children than in adults (13.9 +/- 0.7% versus 11.6 +/- 0.5%/3 x 10(9) cells/mL). Specific binding did not differ between adult males and females. There was no significant correlation between specific binding and reticulocyte count. Scatchard analysis demonstrated a linear plot. Increased binding to red blood cells in the prepubertal children appeared to be due to an increase in receptor affinity (Ka = 4.97 +/- 0.42 x 10(8) M-1 versus 3.70 +/- 0.41 x 10(8) M-1; children versus adults; p = 0.03). Mean receptor concentrations were not different in children and adults (64.4 +/- 8.5 versus 58.0 +/- 5.6 binding sites/cell). There was a significant positive correlation between 125I-Thr59-IGF-I specific binding and affinity (p = 0.007, r = 0.39). We speculate that the greater specific binding of labeled Thr59-IGF-I to red blood cells in prepubertal children may provide a mechanism for enhanced cellular responsiveness to relatively low levels of circulating IGF-I.

Adult↗
PubMed1989

Absence of nonclassical congenital adrenal hyperplasia in patients with precocious adrenarche.

We studied 31 patients (28 girls and 3 boys), ranging in age from 3.2-7.9 yr, with precocious adrenarche defined by the presence of early sexual hair development, no signs of virilization, and bone age within +3 SD of the mean for chronological age. To determine if this symptom complex stemmed from any form of nonclassical (late-onset) congenital adrenal hyperplasia, an ACTH stimulation test was performed on each patient using a standard 0.25-mg dose of Cortrosyn, given as an iv bolus. Twelve pubertal children (7 girls and 5 boys) and 18 prepubertal children (11 girls and 7 boys) served as normal controls. Baseline and stimulated 17-hydroxypregnenolone (17-OHPreg), 17-hydroxyprogesterone, (17-OHP), 11-deoxycortisol, dehydroepiandrosterone, androstenedione, testosterone, and cortisol levels were measured. Using published nomogram standards for serum 17-OHP response to ACTH, no child with precocious adrenarche was diagnosed as having nonclassical 21-hydroxylase deficiency. Eight girls, however, had a stimulated 17-OHP value that exceeded the mean response for pubertal and prepubertal controls by more than +2 SD [range, 295-670 ng/dL (8.94-20.3 nmol/L)]. Stimulated 11-deoxycortisol values [less than 400 ng/dL (11.6 nmol/L)] ruled out any cases of nonclassical 11 beta-hydroxylase deficiency. No patient had nonclassical 3 beta-hydroxysteroid dehydrogenase deficiency, as defined by both the stimulated 17-OHPreg and the 17-OHPreg/17-OHP ratio to be more than +2 SD above the mean for pubertal children [1354 ng/dL (41.0 nmol/L) and 10.4, respectively]. In conclusion, we could not provide any biochemical evidence for nonclassical congenital adrenal hyperplasia in a large group of children with precocious adrenarche.

17-alpha-Hydroxypregnenolone↗
PubMed1989

Pulmonary function testing: sources of error in measurement and interpretation.

Valid pulmonary function data require that attention be paid to issues that can lead to errors in measurement or in interpretation. Routine procedures designed to reduce errors should be established. Among the most important of these are (1) assuring the accurate measurement and calculation of lung function parameters, which requires attention to accuracy when an instrument is brought into service in a laboratory and again when it is updated; (2) selecting reference equations and lower limits of normal appropriate for the patients being studied and for the equipment being used; (3) avoiding the errors introduced by using an excessive number of measurements in generating an interpretation; and (4) avoiding interpretation of results without considering the clinical setting and the pertinent elements of a complete data base.

Equipment Failure↗
PubMed1988

The use of the pelvic radiograph alone to assess therapeutic response in bone metastases from breast cancer.

This study examines the necessity for repeated full skeletal radiographic surveys to assess the response of bone metastases from breast cancer to systemic treatment. This method of evaluating response is compared with that achieved using sequential radiography of the pelvis alone. Sequential changes on pelvic radiographs were identical to those seen on a complete skeletal survey in 87% of the patients studied. In only 6% of the patients were the changes on the pelvic radiographs sufficiently at variance with those on the skeletal survey to suggest a difference in management. It is suggested that sequential radiography of pelvic bones alone is sufficient to assess response of bone metastases in breast cancer in the majority of patients.

Bone Neoplasms↗
PubMed1988

Quantitative assessment of pulmonary edema by nuclear magnetic resonance methods.

Considerable progress has been made in the application of nuclear magnetic resonance (NMR) imaging and nonimaging techniques to the quantitative assessment of pulmonary edema. NMR measurements offer the advantages of being noninvasive, relatively rapid, and easily repeatable. In addition, NMR imaging is suitable for the determination of lung water distribution. Studies of various animal models have shown that NMR techniques can adequately detect and quantify relative changes in lung water content and distribution in various types of experimental lung injury. Preliminary observations in humans suggest that NMR measurement of relative lung water changes in clinical pulmonary edema should be feasible. Although the application of NMR to the assessment of pulmonary edema appears to be very promising, it also poses significant problems that must be solved before it can be established as a standard experimental and clinical method.

Animals↗
PubMed1988

Assessment of lung water distribution by nuclear magnetic resonance. A new method for quantifying and monitoring experimental lung injury.

We have developed a new analytical method that uses nuclear magnetic resonance (NMR) imaging data to quantify lung water content and distribution. This new method generates a distribution of lung water density in which the fraction of voxels corresponding to a given water density is plotted on the vertical axis as a function of water density on the horizontal axis, thereby complementing the spatial information provided by the NMR image. We obtained reproducible lung water distribution data at comparable lung volumes in normal excised lungs and in intact living rats. In normal excised unperfused rat lungs, the distribution varied with the degree of inflation, but the changes were small compared with those associated with lung edema. The lung water density distribution changed markedly after induction of lung edema by intrabronchial saline instillation, intravenous oleic acid injection, and rapid intravenous saline infusion. Lung water density distribution data were well correlated (correlation coefficient = 0.948 for the excised lungs and 0.823 for the intact living rats) with gravimetric lung water measurements. The new analytical method is noninvasive, provides easily repeatable measurements, and is as sensitive as the gravimetric technique to lung water changes.

Animals↗
PubMed1988

Variable estimates of serum growth hormone concentrations by different radioassay systems.

Many different assays are being used to measure serum GH concentrations in children with disorders of growth. We assessed four readily available methods to determine the comparability of the immunopotency estimates: standard double antibody RIA with pituitary standards from the National Hormone and Pituitary Program (assay 1) and from a commercial source (assay 2), a double antibody RIA with serum standards (assay 4), and a commercial immunoradiometric assay (assay 3). There was a high degree of relative correlation between assays (r = 0.95-0.98), but absolute potency estimates differed. Assays 1 and 2 were almost identical. Assay 3 yielded serum GH levels about 65% those of assay 1 or 2 and 80% those of assay 4. Assay 4 gave intermediate values between the low readings in assay 3 and higher values in assay 1 and 2. We conclude that substantial variation occurs in potency estimates in different GH assays. Such differences can affect the interpretation of many GH provocative and sampling studies.

Child↗
PubMed1987

Genetic heterogeneity of X-linked mental retardation with fragile X. Association of tight linkage to factor IX and incomplete penetrance in males.

X-linked mental retardation with fragile X or Martin-Bell Syndrome (MBS) is a frequent cause of mental retardation. So far segregation analysis of MBS in pedigrees ascertained by different, incomplete criteria has produced results, difficult to interpret, which suggest genetic complexity (Sherman et al. 1985). Biochemical and cell biological studies have failed to provide an assay for genetic heterogeneity in MBS and linkage analysis is the only available method. Such analysis, however, is complicated by the incomplete penetrance of the disease in males and the variable penetrance and expression of the defect in heterozygous females. We have used a new approach to test the heterogeneity of recombination between MBS and the coagulation factor IX gene or the anonymous probe 52A in a group of nine families who have sought genetic counselling at Guy's Hospital. We find that both our families alone and our families plus apparently complete samples of pedigrees reported in the literature, separate into two groups: one tightly and one loosely linked to factor IX. In the combined family sample these represent respectively 0.3 and 0.7 of the total and show recombination fractions of 0.0-0.15 and 0.25-0.5. Furthermore, the families with non-penetrant carrier males show tighter linkage to factor IX than the others, thus confirming the suggestion of a systematic difference among MBS families in the recombination between the disease and the factor IX locus. By contrast, no significant differences were found in the recombination between 52A and factor IX in the two groups of MBS families or in these families versus those with Hunter syndrome examined in our laboratory. The causes of the linkage heterogeneity we describe are not known. At least two alternatives can be considered: The existence of two MBS loci or differences in the recombination between a single MBS locus and the factor IX gene. The association between incomplete penetrance and tight linkage to factor IX as well as the discontinuous variation in recombination fraction we have observed seem to favour the former alternative.

Factor IX↗
PubMed1987

Prediction of pulmonary function abnormalities after adult respiratory distress syndrome (ARDS).

To determine if measures of ARDS severity during the acute illness correlate with lung function after recovery from ARDS, we regressed lowest total thoracic compliance (CTH), initial intrapulmonary shunt fraction (Qsp/Qt), initial mean pulmonary artery pressure (PAP), maximal level of positive end-expiratory pressure (PEEP), time ventilated (Tvent), and time with FlO2 greater than 0.6 (TO2) against the percent of predicted FVC, TLC, and DLCO of 16 previously healthy, nonsmoking ARDS survivors. Pulmonary function tests were performed more than 1 yr after ARDS. Percent of predicted FVC correlated with CTH (r = 0.66, p less than 0.01) and PAP (r = 0.53, p less than 0.05), and percent of predicted TLC correlated with CTH (r = 0.71, p less than 0.01), PEEP (r = -0.55, p less than 0.05), and Qsp/Qt (r = -0.53, p less than 0.05). Only TO2 correlated with percent of predicted DLCO (r = -0.53, p less than 0.05). Five of 7 ARDS survivors with an abnormal DLCO were supported at FlO2 greater than 0.6 for more than 24 h, whereas all of 9 survivors with a normal DLCO received FlO2 greater than 0.6 for less than 24 h. We conclude that physiologic markers of ARDS severity during the acute illness correlate with residual pulmonary dysfunction after recovery from ARDS. Support with FlO2 greater than 0.6 for more than 24 h appears to be a sensitive and specific predictor of an abnormally reduced DLCO more than 1 yr after ARDS.

Adolescent↗
PubMed1987

A pressure-limited critical care ventilator.

We developed a new pressure-limited ventilator system by modifying the Bird #7001M ventilator. Our aims were to free ICU floor space by wall-mounting the ventilator, and to employ a pressure-limited, gas-powered ventilator similar to our transport ventilator to aid in the training of members of our transport team. The system provides a peak pressure of 150 cm H2O and a peak flow of 208 L/min. When coupled with heated pneumatic nebulizers, it quietly provides a maximum gas flow of 208 L/min with nebulized water at 37 degrees C. We successfully used this system for over 4 years to provide a wide range of ventilatory support and oxygen therapy.

Equipment Design↗