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Biomedical subjects

G A Rose

Publications and source records attributed to G A Rose.

At least 19 recordsLinked to original sources
PubMed2001

Morphometric analysis of miniature swine hearts as potential human xenografts.

Miniature swine are considered to be potential donors for clinical cardiac transplantation. However, it is unclear how an appropriately sized porcine donor will be selected for a particular human recipient. To address this issue, we performed a morphometric study of the swine heart using transthoracic echocardiography (n = 26) to determine the diameters of the aortic annulus and root, pulmonary artery annulus, and mitral valve annulus. We also obtained direct ex vivo measurements of swine heart weight and linear dimensions (n = 71). Relationships between a swine's height, weight, length, chest circumference and these internal and external cardiac dimensions are described. The strongest correlations were found between a pig's body length and its aortic annulus and root diameters (r-values = 0.97). These relationships are accurately described by univariate linear regression models. By cross-relating our morphometric measurements of aortic annulus diameter in the miniature swine with normative human data, we were able to develop a nomogram, relating swine length and human height, which predicts which miniature swine would donate the best size-matched heart for a particular human recipient.

Animals↗
PubMed1999

Abnormal global left ventricular relaxation occurs early during the development of pharmacologically induced ischemia.

In animal and human models, left ventricular (LV) diastolic function has been observed to be highly sensitive to myocardial ischemia. The response of LV diastolic parameters to pharmacologically induced ischemia, however, has not been characterized and might be important in the interpretation of dobutamine stress echocardiography. Eight mongrel dogs, in which were inserted a high-fidelity micromanometer LV catheter, coronary sinus sampling catheter, and ultrasonic coronary artery flow probe, underwent intravenous dobutamine infusion at escalating doses both before (control protocol) and after (ischemia protocol) creation of left anterior descending coronary artery stenosis with a hydraulic cuff occluder adjusted to maintain resting coronary artery flow but attenuate reactive hyperemia. At each dobutamine dose, epicardial short-axis 2-dimensional echocardiographic images and hemodynamic measurements were obtained. LV diastolic function was examined by calculation of peak (-)dP/dt and the time constant of isovolumic relaxation (tau). The dobutamine infusion protocol was terminated on the earliest recognition of an anterior wall motion abnormality. Peak (+)dP/dt normalized for developed isovolumetric pressure was calculated as a relatively load-independent index of global LV contractile function. Dobutamine infusion with and without ischemia resulted in comparable changes in heart rate and (+)dP/dt/IP, with no change in LV end-diastolic or -systolic pressure. The magnitude of peak (-)dP/dt increased less during the ischemia (1231 +/- 109 to 1791 +/- 200 mm Hg/sec) versus the control (1390 +/- 154 to 2432 +/- 320 mm Hg/sec) protocol (P <.05). Similarly, the observed decrease in tau was less during the ischemia (53 +/- 3 to 38 +/- 4 msec) than the control (51 +/- 5 to 23 +/- 3 msec) protocol, corresponding to a slower rate of relaxation (P <.05). In addition, the smaller decrease in tau was observed at the dobutamine dose before the dose at which an echocardiographic wall motion abnormality was first recognized. Dobutamine-induced ischemia is associated with abnormal LV diastolic function. In addition, these abnormalities seem to occur early in the development of ischemia. These observations extend to pharmacologically induced ischemia prior findings from other models of ischemia, suggesting the high sensitivity of LV diastolic function to the development of myocardial ischemia.

Animals↗
PubMed1998

Accurate localization of mitral regurgitant defects using multiplane transesophageal echocardiography.

BACKGROUND: Appropriate patient selection for surgical repair of the mitral valve depends on the specific location and mechanism of regurgitation, which, in turn, has necessitated a more detailed method to accurately describe mitral pathology. This study tests a strategy of using multiplane transesophageal echocardiography to systematically localize mitral regurgitant defects and compares these results with the surgical findings. METHODS: Fifty patients with mitral regurgitation underwent intraoperative transesophageal echocardiography for the evaluation of mitral pathology and potential repair. Mitral regurgitant defects were localized using a systematic strategy and a simple nomenclature that divides each mitral valve into six sections (three sections per leaflet) and each prosthetic sewing ring into six sections (60 radial degrees = one section). RESULTS: Thirty-nine patients with native mitral valves were studied, for a total of 234 sections evaluated. Eighty-seven of these sections contained regurgitant defects by transesophageal echocardiography (mean number of regurgitant defects per valve, 2.2; range, 1 through 6). There was agreement between the transesophageal echocardiographic and surgical localizations in 96% (224/234; p < 0.0001) of the sections. Eleven patients with prosthetic mitral valves were studied, for a total of 66 sections evaluated. Twenty-three of these sections contained paravalvular leaks by transesophageal echocardiography (mean number of leaks per prosthesis, 2.1; range, 1 through 6). There was agreement between the transesophageal echocardiographic and surgical localizations in 88% (58/66; p < 0.001) of the sections. CONCLUSIONS: This transesophageal echocardiographic strategy provides a systematic method to accurately localize mitral regurgitant lesions and has the potential to improve the preoperative assessment of patients with significant mitral regurgitation.

Diagnostic Techniques, Surgical↗
PubMed1998

Coronary endothelial dysfunction in patients with acute-onset idiopathic dilated cardiomyopathy.

OBJECTIVES: This study sought to determine whether coronary endothelial dysfunction exists in patients with acute-onset idiopathic dilated cardiomyopathy (DCM) and to explore its relation to recovery of left ventricular systolic function in this patient population. BACKGROUND: Coronary endothelial dysfunction exists in chronic DCM, but its importance in the development and progression of ventricular dysfunction is not known. To address this issue we studied coronary endothelial function in patients with idiopathic DCM <6 months in duration and explored the relation between coronary endothelial function and subsequent changes in left ventricular ejection fraction (LVEF). METHODS: Ten patients with acute-onset idiopathic DCM (duration of heart failure symptoms 2.0 +/- 0.4 months [mean +/- SEM]) and 11 control patients with normal left ventricular function underwent assessment of coronary endothelial function during intracoronary administration of the endothelium-dependent vasodilator acetylcholine and the endothelium-independent vasodilator adenosine. Coronary cross-sectional area (CSA) was determined by quantitative coronary angiography and coronary blood flow (CBF) by the product of coronary CSA and CBF velocity measured by an intracoronary Doppler catheter. Patients with DCM underwent assessment of left ventricular function before and several months after the study. RESULTS: Acetylcholine infusion produced no change in coronary CSA in control patients but significant epicardial constriction in patients with DCM (-36 +/- 11%, p < 0.01). These changes were associated with increases in CBF in control patients (+118 +/- 49%, p < 0.01) but no change in patients with DCM. Infusion of adenosine produced increases in coronary caliber and blood flow in both groups. Follow-up assessment of left ventricular function was obtained in nine patients with DCM 7.0 +/- 1.7 months after initial study, at which time LVEF had improved by > or =0.10 in four patients. Multiple linear regression revealed a positive correlation between both the coronary CSA (r2 = 0.57, p < 0.05) and CBF (r2 = 0.68, p < 0.01) response to acetylcholine and the subsequent improvement in LVEF. CONCLUSIONS: Coronary endothelial dysfunction exists at both the microvascular and the epicardial level in patients with acute-onset idiopathic DCM. The preservation of coronary endothelial function in this population is associated with subsequent improvement in left ventricular function.

Acetylcholine↗
PubMed1998

Experiences in Hong Kong with the theory and practice of the albumin column method of sperm separation for sex selection.

Controversy still surrounds the human serum albumin (HSA) method for separation of X- and Y-bearing human spermatozoa. There is doubt about whether the procedure does enrich sperm samples for the chosen sex chromosome. We have applied the HSA separation method in a clinic in Hong Kong, using the method as described by Ericsson et al. [Nature, 246, 421-424 (1973)] taking care to keep the sperm recovery to <5% of the initial number. Aliquots of separated spermatozoa were examined for X- and Y-bearing spermatozoa by fluorescent in-situ hybridization (FISH) using appropriate DNA probes. Of 18 couples wanting boys, 13 had single boys, one had twin boys, and one had twins comprising one boy and one girl. Only three single girls were born. This success rate of 83% is significantly different (P < 0.001) from the usual expected ratio. There were four miscarriages, one in the third and one in the fourth week of pregnancy. The times of the others are not definitely known, but are thought to have occurred early in pregnancy. We lack information on three couples. The FISH procedure showed no change in the normal and equal numbers of X- and Y-bearing spermatozoa after the HSA separation procedure. This study confirmed that the HSA sperm separation method can bias the number of babies in favour of males. However, the theory that it does so by enriching the sperm samples with Y-bearing spermatozoa appears to be incorrect and some other theory has to be postulated. It is tentatively proposed that passage through the HSA inactivates X-bearing spermatozoa more than Y-bearing spermatozoa, even though this is not apparent simply on inspection of sperm motility.

Cell Separation↗
PubMed1997

Effects of prolonging peak dobutamine dose during stress echocardiography.

OBJECTIVES: This study sought to test whether the physiologic advantage of a prolonged dobutamine stage during stress echocardiography can be effectively combined with a clinically practical infusion protocol. BACKGROUND: Dobutamine has a half-life of 2 min and requires up to 10 min to achieve steady state. Despite these known pharmacodynamics, dobutamine stress echocardiography is routinely performed by advancing doses at 3-min intervals. Canine studies have shown that dobutamine stress echocardiography end points will occur at a lower dose if each stage is prolonged, but these findings have yet to be used in the clinical setting. METHODS: The standard 3-min dobutamine dose stage during stress echocardiography was modified by extending the peak dose (40 micrograms/kg body weight per min) for an additional 2 min. Consecutive patients underwent this modified protocol to test whether the requirement for atropine could be reduced. According to this modified protocol, if a dobutamine stress echocardiographic end point (85% of maximal predicted heart rate, new wall motion abnormalities, hypotension, arrhythmia or intolerable symptoms) was not reached at 3 min of the peak dose, this dose was prolonged for an additional 2 min. If a doubtamine stress echocardiographic end point was still not attained, atropine (up to 1.0 mg intravenously) was administered. RESULTS: The study included 84 patients, 22 of whom (26.2%) achieved a dobutamine stress echocardiographic end point using the standard 3-min stage. Of the 62 patients who did not reach an end point in the initial 3 min of peak dobutamine dose, the additional 2 min of dobutamine increased heart rate (from 99.6 +/- 23.8 to 107.2 +/- 23.2 beats/min, p < 0.01) and allowed 20 patients (32.3%, p < 0.01) to attain an end point. Of the remaining 42 patients, 23 never achieved a stress echocardiographic end point, despite 1.0 mg of atropine. One patient developed supraventricular tachycardia during the additional 2 min of dobutamine, and one developed nonsustained ventricular tachycardia after receiving atropine. CONCLUSIONS: These data demonstrate that a significant number of patients (32%) who do not reach a dobutamine stress echocardiographic end point with the standard protocol can safely attain an end point solely by extending the duration of the peak dose. Adoption of this strategy may reduce the need for supplemental atropine and its potential adverse effects.

Adult↗
PubMed1995

Social aspects of > 800 couples coming forward for gender selection of their children.

The social characteristics of 809 couples attending a sex preselection clinic have been studied. Their ethnic origins were: Indian 57.8%, European 32.0%, Chinese 3.6% and others 6.8%. The average number of boys and girls per family was 0.09 and 2.70 respectively for couples wanting a boy, and 2.46 and 0.14 for those wanting a girl. The average age of the wives was 34.0 years. These figures were not significantly different in any ethnic subgroup. Out of all the couples, 80.6% stated that they would have had another baby even had sex preselection not been on offer; 37.5% of the couples interviewed have been treated so far. The figures among those treated are substantially the same as those for the whole group. Asian and Middle Eastern couples overwhelmingly wanted boys, whereas European couples showed a slight preference for girls. These results suggest that, given certain guidelines, sex selection is unlikely to lead to a serious distortion of the sex ratio in Britain and other Western societies, but may need careful monitoring in other parts of the world.

Adult↗
PubMed1994

A clinical rule to predict preserved left ventricular ejection fraction in patients after myocardial infarction.

OBJECTIVE: To derive and validate a clinical prediction rule that identifies patients after myocardial infarction who have preserved left ventricular systolic function. DESIGN: Retrospective analysis of a prospective cohort study, with a derivation set to generate a clinical prediction rule and a validation set to test the prediction rule. SETTING: Urban tertiary care hospital. PATIENTS: 314 consecutive patients admitted with myocardial infarction who had one or more of the following tests to determine left ventricular ejection fraction: transthoracic echocardiography, contrast left ventriculography, or radionuclide ventriculography. MEASUREMENTS: Left ventricular ejection fractions were determined by transthoracic echocardiography, contrast left ventriculography, and gated blood pool scan. RESULTS: Multivariate analysis of patients in the derivation set yielded the following rule: The left ventricular ejection fraction is predicted to be 40% or more in patients who have 1) an interpretable electrocardiogram, 2) no previous Q-wave myocardial infarction, 3) no history of congestive heart failure, and 4) an index myocardial infarction that is not a Q-wave anterior infarction. In the derivation and the validation sets, the positive predictive value of the prediction rule was more than 0.98. CONCLUSIONS: A simple clinical prediction rule using easily obtained historical and electrocardiographic data reliably identifies a substantial percentage of patients after myocardial infarction (40% in our hospital) who are likely to have preserved left ventricular systolic function. If validated in other patient populations, application of this prediction rule in clinical practice could result in a substantial decrease in the cost of treating uncomplicated myocardial infarction.

Aged↗
PubMed1992

Recurrent infection stones with apparently negative cultures. The case for blind antibacterial treatment.

Infection stones in the urinary tract are always associated with infection with a urease-producing, urea-splitting organism. The most common of these organisms are easy to culture and identify and can be treated early either with an appropriate antibiotic or with an anti-urease agent. Ureaplasma urealyticum and Corynebacterium urealyticum are urease-producing organisms which are difficult to grow; their presence and effects frequently go undetected and untreated. Other organisms, as yet unknown, may also be involved in the same process. We report the first series of 8 patients with recurrent infection-type stones likely to have been caused by a "hard to grow" organism. Five patients never had a positive culture; in 2 patients 1 of 10 urine cultures grew a coagulase-negative Staphylococcus and in 1 patient the same organism was grown from a stone but never in the urine. The clinical course of all of these patients was significantly improved after blind treatment with antibiotics and in one case with an anti-urease agent.

Adult↗
PubMed1991

Metabolic balance studies of mineral supplementation in osteoporosis.

1. We studied the effect of mineral supplementation and its duration in osteoporosis by analysing the calcium and phosphorus balances of 49 treated osteoporotic patients whose median length of calcium treatment was 19 weeks with a range of 8 days to over 4 years. Forty-four studies satisfied statistical criteria of reproducibility and included 35 women (10 also receiving oestrogen replacement therapy) and nine men. 2. Mean calcium balance was positive in women taking calcium supplements alone, +1.9 +/- 2.5 mmol daily (P less than 0.002), and was significantly more positive (P less than 0.05) in women also taking oestrogens, +4.2 +/- 2.1 mmol daily. Calcium balance was not significantly positive in men. 3. Calcium balance correlated negatively with duration of supplementation, but significantly, only when duration of supplementation was expressed logarithmically (r = -0.401, P less than 0.01) giving the regression equation y = 4.2-1.6 log x, where y = calcium balance in mol/day and x = duration of supplementation in weeks. Theoretical net calcium retention, without allowance for dermal loss, could be calculated by integration. 4. Mean phosphorus balance was significantly positive in both groups of women and in the whole population. Although its correlation with duration of supplementation did not reach statistical significance (P less than 0.1), the ratio of the regression slopes for calcium and phosphorus, 1.5:1, corresponded to their molar ratio in bone. 5. These statistics are, we believe, the first to describe an exponential decline in calcium balance during mineral treatment of osteoporosis, but they firmly suggest that such treatment, with or without oestrogen therapy, conveys temporary benefit.

Aged↗
PubMed1991

Blood and urine analysis in patients with intestinal bladders.

A group of 183 patients whose urine was stored in pouches formed either wholly or partly from bowel was reviewed to establish abnormal biochemical and haematological factors and to assess the risk of infection. Minimum follow-up was 1 year (range 1-28.5, mean 3 years 8 months) and the mean age of the patients at follow-up was 16.5 years (range 4-43). Pouches were augmentation and substitution cystoplasties and complete reconstructions with bowel. Bowel segments were ileum (55 patients), colon (100) and mixed (28). Anaemia was found in 15 patients, folate deficiency in 2 and folate excess in 2. Definite hyperchloraemic acidosis was found in 25 patients and borderline results in 40. Most of these patients had colon in the pouch but 5 definite and 13 borderline cases had ileum only. Troublesome urinary infections occurred in 27.9% of patients; 3 developed renal stones and 22 developed pouch/bladder stones. Stones were usually associated with infection and/or staples. Delayed linear growth occurred in 20% of children in spite of a normal increase in weight; there was no difference in any of the measurements between those who grew and those who did not.

Adolescent↗
PubMed1991

Urinary oxalate and glycolate excretion and plasma oxalate concentration.

The diagnosis of primary hyperoxaluria in young children is hampered by the lack of a reliable reference range for urinary oxalate excretion, especially in infants. We present data on urinary oxalate and glycolate excretion in 137 normal children, on the plasma oxalate concentration in 33 normal children and 53 with chronic renal failure, and on amniotic fluid oxalate concentration in 63 uncomplicated pregnancies. The urinary oxalate:creatinine molar ratios were log normally distributed: mean (range) values were less than 1 year 0.061 (0.015-0.26), 1-5 years 0.036 (0.011-0.12), 5-12 years 0.030 (0.0059-0.15), and greater than 12 years 0.013 (0.0021-0.083). Geometric mean (range) plasma oxalate concentration in the normal children was 1.53 (0.78-3.02) mumols/l and was independent of age. The mean (SD) plasma oxalate: creatinine molar ratio in these normal children and 50 with chronic renal failure was 0.033 (0.013), and was independent of age and renal function. Mean (SD) amniotic fluid oxalate concentration was 19.0 (4.3) mumols/l.

Adolescent↗
PubMed1991

Metabolism of pyridoxine in mild metabolic hyperoxaluria and primary hyperoxaluria (type 1).

Plasma pyridoxine metabolites in plasma and 4-pyridoxic acid excretions in urine were measured in normal subjects, in 7 patients with type-1 hyperoxaluria and in 8 patients with mild metabolic hyperoxaluria, while receiving various doses of pyridoxine. Compliance with ingestion of pyridoxine was verified by measuring urinary 4-pyridoxic acid. In the normal subjects the maximum level of pyridoxal phosphate was obtained after only 10 mg/day of pyridoxine. The patients were divided into nonresponders, good responders and poor responders to pyridoxine according to the fall in urinary oxalate and glycollate excretions. In patients taking pyridoxine, the plasma pyridoxal phosphate levels were as for normal subjects in primary hyperoxaluria, lower than for normal subjects in mild metabolic hyperoxaluria (p less than 0.01), and in the latter group lower in partial responders than in good responders (p = 0.04). Hence in mild metabolic hyperoxaluria there may be difficulty in converting pyridoxine to pyridoxal phosphate.

Chromatography, High Pressure Liquid↗