Microscopic theory of epitaxial growth on vicinal surfaces.
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Journal Article↗
Biomedical subjects
S Harris
Publications and source records attributed to S Harris.
An integrated software system for quality assurance-related kappa coefficient analysis of intraoperative transesophageal echocardiography interpretive skills.
This report describes the development of a quality assurance-oriented integrated software system designed for an anesthesiology-based intraoperative transesophageal echocardiography service. Entry data include patient and operation demographics, two-dimensional echocardiographic, saline-contrast, and color flow/pulsed Doppler assessments of the heart and great vessels, presented in a defined sequence. A statistical analysis component (kappa coefficient analysis) allows for comparison of intraoperative real-time interpretations with laboratory interpretations made by experienced full-time echocardiographers on a field-by-field basis. This provides a means of quantifying expertise in each individual aspect of the patient examination sequence. We believe that such self-appraisal data are essential for delineating the status and tracking the progress of service being provided.
Echocardiography, Transesophageal↗
Calcium retention and hormone levels in black and white women on high- and low-calcium diets.
Black-white differences in calcium metabolism are sought because they may reveal why blacks have higher bone mass than whites. Comparative studies of calcium absorption in blacks and whites are not available. In this study, we compare fractional calcium retention, an index of calcium absorption, and calcium regulating hormone levels in black and white women on a high-calcium diet and after adaptation to a low-calcium diet. A total of 30 healthy women (15 black and 15 white) had measurements of fractional 47Ca retention and calcium regulating hormone levels after 8 weeks on a 2000 mg calcium diet and, subsequently, after 1, 2, 4, and 8 weeks on a 300 mg calcium diet. By 2 weeks after the diet change, fractional 47Ca retention, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D [1,25-(OH)2D] had reached a plateau at higher levels, urine calcium at a low level, and serum calcium at the same level (repeated-measures ANOVA). Fractional 47Ca retention, serum calcium, and PTH were similar on both diets in blacks and whites. Blacks had higher levels of 1,25-(OH)2D on both diets (e.g., 125.1 +/- 53.5 SD versus 73.4 +/- 19.0 pmol/liter, P = 0.003 on low-calcium diet) and a greater increase in 1,25-(OH)2D after the diet change (33.9 +/- 30.1 SD versus 11.8 +/- 17.9 pmol/liter, P = 0.021). Serum phosphorus was lower in blacks throughout. For hormone levels and fractional calcium retention to stabilize after a diet change, 2 weeks was needed.(ABSTRACT TRUNCATED AT 250 WORDS)
Absorption↗
A clinical computer database entry form for an intraoperative anesthesiology-based transesophageal echocardiography monitoring service.
Transesophageal echocardiography (TEE) has been increasingly applied to supplement and, in instances, to supplant conventional intraoperative cardiac monitoring. Our body of experience (> 1600 intraoperative TEE procedures), combined with insights gleaned from an intramural quality assurance study, and clinical implications of certain recent advances in the field, led us to develop the following TEE computer database entry form. The form, completed intraoperatively, consists of a patient and surgical procedure demographics section, followed by fields based on the TEE examination. The scans encompass transverse plane basal short axis, long axis, and transgastric views of the heart and great vessels. The two-dimensional echocardiographic, saline-contrast, color flow and pulsed Doppler data represent both right and left ventricular performance, valvular function and specific lesions. This database entry form is intended to serve as a guide for performance of a nominally complete intraoperative study and facilitate maintenance of a TEE archive consistent with current advances.
Anesthesia Department, Hospital↗
Risk factors for bone loss in healthy postmenopausal women.
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Body Weight↗
Transgenic animals as tools in drug development.
A transgenic animal can be defined as an organism that has undergone a stable modification of genotype as a result of genetic manipulation. Such animals are being increasingly employed as research and development tools by both academic and commercial institutions. The primary methods by which transgenic animals can be generated will be described. The relative merits of the approaches will be illustrated, as will their potential use in the discovery and development of novel therapeutic entities.
Animals↗
Seasonal mood changes in 250 normal women.
A 1-year prospective study of seasonal mood changes was conducted in 250 female Boston area residents, aged 43 to 72, who were participants in a study of vitamin D supplementation. Each woman completed the Profile of Mood States questionnaire at four study visits. There were significant changes over the year in scores for Tension-Anxiety, Depression-Dejection, Anger-Hostility, Fatigue-Inertia, and Confusion-Bewilderment. These scores were all highest or "worst" in the fall and lowest in the spring or summer. Worse mood scores were associated with fewer hours of sleep. Serum thyroxine was positively associated with higher Depression-Dejection scores in August through November and with higher (better) Vigor-Activity scores in February through May. Supplementation with 400 IU of vitamin D did not appear to affect levels or changes in mood scores.
Adult↗
Transesophageal two-dimensional echocardiographic analysis of right ventricular systolic performance indices during coronary artery bypass grafting.
Sixteen patients (aged 59 +/- 14 years) undergoing coronary artery bypass surgery were evaluated to delineate the intraoperative course of transesophageal echocardiographic right ventricular (RV) systolic performance indices. Pre-induction data included thermodilution RV ejection fraction (RVEFTD), 0.43 +/- 0.13, RV end-diastolic volume index (EDVI), 110 +/- 33 mL/m2, cardiac index (CI), 3.4 +/- 1.0 L/min/m2, RV end-diastolic pressure (EDP), 7.1 +/- 4.2 mmHg, and mean pulmonary artery pressure (PAP), 21 +/- 6 mmHg. Eleven patients had significant right coronary artery (RCA) disease (> 70% occlusion). Five patients arrived with an ongoing nitroglycerin infusion (1 to 3 micrograms/kg/min), which was maintained intraoperatively. Echocardiographic measurements included longitudinal-axis (LA) and short-axis (SA) planimetered area excursion fractions (2DLA and 2DSA, respectively) and LA maximal major and minor axis shortening fractions (max majorLA and max minorLA, respectively). Hemodynamic measurements included RVEFTD, EDVI, CI, EDP, and PAP. Measurements were determined following induction/endotracheal intubation, following sternotomy/pericardiotomy, and after cardiopulmonary bypass (CPB) with the chest open. All patients were maintained on vasodilator therapy post-CPB (nitroglycerin, 1 to 3 micrograms/kg/min [N = 16] and nitroprusside, 0.5 to 4.5 microgram/kg/min [N = 4]) post-CPB. Two patients received inotropic support (epinephrine, 0.2 to 0.3 microgram/kg/min). CPB was associated with significant decreases in max major axisLA and 2DLA (P < 0.05) as compared to measurements determined prior to CPB. Maximum major axisLA values pre-CPB were 0.35 +/- 0.06 and 0.33 +/- 0.08 versus post-CPB values of 0.24 +/- 0.08.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Pressure↗
Thiazides and seasonal bone change in healthy postmenopausal women.
Thiazide diuretic use has been associated with reduced rates of bone loss and bone density has been found to fluctuate with time of year. Here we examine associations between thiazide use, calcium regulating hormones, and the pattern of bone change during the 6-month intervals of summer/fall when bone density increases and winter/spring when bone density declines. Of the 246 postmenopausal women who completed a 1-year calcium and vitamin D supplement trial, 25 used a thiazide diuretic. In the winter/spring, bone loss was reduced in the thiazide users (for L2-4: 0.46 +/- 0.59 (SE)% for thiazide users vs. -1.02 +/- 0.17% for non-users, P = 0.017; for whole-body: -0.13 +/- 0.25% vs. -0.67 +/- 0.08, P = 0.043). The benefit at the whole body was dose related. Increases in bone density were similar in the two groups in the summer/fall. Associations between thiazide use and net spinal change and between thiazide dose and net whole-body bone change were positive. Thiazide users had lower serum levels of PTH (26.2 +/- 7.6 (SD) ng/l vs. 31.0 +/- 11.7 ng/l, P = 0.009) and 1,25-dihydroxyvitamin D (60.8 +/- 16.2 pmol/l vs. 77.0 +/- 18.7 pmol/l, P < 0.001) in the winter/spring and, in the subset measured, reduced levels of osteocalcin year round (summer/fall: 2.89 +/- 0.82 micrograms/l, n = 10, vs. 3.65 +/- 1.02, n = 82, P = 0.019; winter/spring: 2.54 +/- 0.80 micrograms/l vs. 3.47 +/- 1.07 micrograms/l, P = 0.005). Sodium excretion in the two groups did not differ in the winter/spring. In conclusion, beneficial bone effects of thiazide diuretics occur in the winter/spring and they may result from a decrease in PTH-stimulated bone resorption and an associated reduction in the bone turnover rate.
Aged↗
Malignant (metastatic) ameloblastoma: report of a case.
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Adult↗
Non-Hodgkin's lymphoma: an unusual cause of myocardial infarction and hypercalcaemia.
Cardiac involvement is reported in 10%-20% of patients with lymphoma, but it is characteristically difficult to detect clinically or by investigation. Hypercalcaemia is a rare complication. Both complications usually occur late in the natural history of lymphoma. We report a case of non-Hodgkin's lymphoma, who, within 2 weeks of presentation, developed symptomatic hypercalcaemia and, 3 days later, died of an acute myocardial infarction. Autopsy showed, unexpectedly, the unusual finding of coronary artery compression by lymphomatous deposits.
Aged↗
Epidemiology of Toxocara canis in red foxes (Vulpes vulpes) from urban areas of Bristol.
A descriptive epidemiological survey was undertaken of the ascarid nematode Toxocara canis in 521 red foxes (Vulpes vulpes) during the period January 1986 to July 1990. Age-prevalence and age-intensity profiles show that worm burdens are significantly higher in cubs than in subadult or adult foxes and higher in subadult than in adult foxes. Seasonal variations in worm burdens occur, with the highest prevalences and intensities being found during the spring, when cubs are born, and in the summer months. Prevalences and intensities then decrease during the autumn and winter months in both subadult and adult foxes, but, during this period, prevalences are significantly higher in male than in female foxes. Variations in worm burdens in the fox population are likely to be related to the reproductive cycle of the fox, with a high proportion of cubs becoming infected in utero. The role of the fox in the transmission of T. canis in the urban environment is discussed.
Age Factors↗
Gene conversions and crossing over during homologous and homeologous ectopic recombination in Saccharomyces cerevisiae.
The pma1-105 mutation reduces the activity of the yeast plasma membrane H(+)-ATPase and causes cells to be both low pH and ammonium ion sensitive and resistant to the antibiotic hygromycin B. Revertants that can grow at pH 3.0 and on ammonium-containing plates frequently arise by ectopic recombination between pma1-105 and PMA2, a diverged gene that shares 85% DNA sequence identity with PMA1. The gene conversion tracts of revertants of pma1-105 were determined by DNA sequencing the hybrid PMA1::PMA2 genes. Gene conversion tracts ranged from 18-774 bp. The boundaries of these replacements were short (3-26 bp) regions of sequences that were identical between PMA1 and PMA2. These boundaries were not located at the regions of greatest shared identity between the two PMA genes. Similar results were obtained among low pH-resistant revertants of another mutation, pma1-147. One gene conversion was obtained in which the resulting PMA1::PMA2 hybrid was low pH-resistant but still hygromycin B-resistant. This partially active gene differs from a wild-type revertant only by the presence of two PMA2-encoded amino acid substitutions. Thus, some regions of PMA2 are not fully interchangeable with PMA1. We have also compared the efficiency of recombination between pma1-105 and either homeologous PMA2 sequence or homologous PMA1 donor sequences inserted at the same location. PMA2 x pma1-105 recombination occurred at a rate approximately 75-fold less than PMA1 x pma1-105 events. The difference in homology between the interacting sequences did not affect the proportion of gene conversion events associated with a cross-over, as in both cases approximately 5% of the Pma+ recombinants had undergone reciprocal translocations between the two chromosomes carrying pma1-105 and the donor PMA sequences. Reciprocal translocations were identified by a simple and generally useful nutritional test.
Crossing Over, Genetic↗
Infrared tympanic thermometry in the pediatric intensive care unit.
OBJECTIVES: To determine the performance of two different commercially available, noncontact infrared tympanic thermometers in predicting core body temperature as measured by pulmonary artery catheters in pediatric intensive care unit (ICU) patients. The performance of the tympanic thermometers was compared with the performance of an indwelling rectal probe and digital axillary temperature determinations. DESIGN: Prospective, consecutive sample, unblinded study. SETTING: Pediatric ICU of a tertiary care children's hospital. PATIENTS: Twenty patients requiring pulmonary artery catheter monitoring for clinical management. INTERVENTIONS: Temperature measurements were made using each infrared tympanic thermometer unit in the core mode. These values were compared with simultaneously obtained pulmonary arterial, digital axillary, and rectal probe temperatures. MEASUREMENTS AND MAIN RESULTS: Bias and variability of each method compared with the pulmonary arterial temperature were calculated. Bias did not vary with temperature measured or age of the patient. Indwelling rectal probes showed the least bias and variability and axillary temperature the most. Neither infrared tympanic thermometer had clinically important bias; one model had variability similar to that of the rectal probes, and the other model had significantly greater variability. CONCLUSIONS: In a pediatric ICU population, rectal probes reflect core temperature better than axillary determinations and both infrared tympanic models estimated core body temperature better than digital axillary temperature. One of the tympanic systems (Thermoscan Pro-1 infrared tympanic thermometer) performed in a similar way to the indwelling rectal probes and may be used to estimate core temperature in situations where a pulmonary artery catheter is not in place. The other test tympanic system (First Temp) had greater variability than the rectal probes.
Adolescent↗
Electrical brain stem responses in cochlear implant patients.
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Artifacts↗
Quality assurance for intraoperative transesophageal echocardiography monitoring: a report of 846 procedures.
We evaluated our experience with 846 consecutive transesophageal echocardiography (TEE) intraoperative monitoring procedures performed between November 1989 and July 1991. TEE frequency was 36 +/- 11 per month (range 16-55) and represented 69.8% of cardiac valve surgery cases, 40.2% of coronary artery bypass graft cases, and 2.2% of total operative caseload. Major patient complications consisted of transient vocal cord paresis and ingestion of glutaraldehyde-disinfectant solution. Minor complications consisted of a chipped tooth (one case) and pharyngeal abrasions (three cases). The Quality Assurance (Q/A) Program evaluated both record keeping and quality of imaging, as judged by cardiologist echocardiographer reviewers. The percentage of completion for each Q/A indicator was as follows: medical record documentation, 88%; database form annotation, 94%; and provision of videotape recording, 91%. TEE database forms were analyzed further in terms of the percentage of fields completed. Completion scores were 73%. The following scoring system was utilized for videotape evaluation by the cardiologists: 1 = excellent; 2 = good; 3 = poor. The median grade for both two-dimensional echocardiography and color flow Doppler (CFD) examinations was 2. Poor quality images (grade 3) were present in 15.2% of two-dimensional echocardiography and 20.3% of color flow Doppler examinations, and disproportionately associated with 4/26 attendings. Supplemental audit of the cardiology reviewers performance demonstrated 569/846 videotapes showed no objective evidence of review. The cardiology reviewer forms of the remaining 277 videotapes were evaluated in terms of the percentage of fields completed. The completion score was 56%. These data suggest the need for formal Q/A for intraoperative TEE, both for anesthesiologists and reviewing cardiologists.
Echocardiography↗
Angiotensin-converting enzyme inhibitor treatment for young normotensive diabetic subjects: a two-year trial.
Microangiopathy characterizes both diabetic retinopathy and nephropathy. It is currently unclear which diabetic subjects should be treated with angiotensin-converting enzyme (ACE) inhibitors. A double-blind, placebo-controlled protocol was implemented using captopril to treat subjects with Type I diabetes, early diabetic nephropathy (albumin excretion rates, 20-200 micrograms/min), and normal blood pressures. After two years, the final eye grades were improved in two treated subjects but not in any of the controls. Three control and one treated subject showed worsening of their eye grade after two years (P < .001, by chi-square test). Significant differences in renal albumin excretion were not seen between the two groups. The distribution of changes in retinal grades in the treatment group compared with the placebo group was improved after two years. Studies of larger numbers of patients will be necessary to determine if ACE inhibitors should be used routinely in subjects with diabetic retinopathy and to determine which subjects are most likely to respond.
Adolescent↗
Cartilage warping: an experimental model.
Cadaveric cartilage was cut into blocks with a newly devised cartilage cutter. Over one-hundred pieces of cartilage were used to define a kinetics curve of cartilage warping. Kinetics curves were developed for a control group of cartilage blocks placed in saline-soaked gauze (n = 46). In addition, kinetics curves were developed for cartilage placed in hypotonic saline (n = 14), hypertonic saline (n = 14), and cyanoacrylate glue (n = 6). Photographs of all groups were taken at timed intervals in order to plot the cartilage warping. It was found that pieces of cartilage which were cut peripherally (n = 6) warped twice as much as those cut centrally (n = 40). This was significant to p = 0.001. Within 15 minutes, centrally cut pieces of cartilage warped to approximately 90 percent of their end warpage; on the other hand, peripherally cut pieces of cartilage required 30 minutes to warp 90 percent of their destined warpage. The variables used did not significantly alter the kinetics curves as compared with control.
Cadaver↗