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Biomedical subjects

J D Esser

Publications and source records attributed to J D Esser.

At least 19 recordsLinked to original sources
PubMed1998

A method for creating reversible ureteric obstruction in the primate.

A technique has been developed for the establishment of a state of reversible, ureteric obstruction in the primate. Ten adult males had baseline 99mTc-DTPA renogram studies. A randomly selected ureter was totally occluded and obstruction confirmed on renogram. The occlusion was reversed and subsequent renograms confirmed recovery of activity in the obstructed kidneys of the eight animals who survived the reversal procedure. Seven were alive on conclusion of the study. Prevention of ureteric strictures was achieved with an intra-ureteric silastic tube. Autopsies demonstrated patency of every previously occluded ureter. This is the first study to be reported in primates, and the second overall, in which complete ureteric obstruction and its successful reversal has been confirmed on renogram using this surgical method. The technique is suitable for the study of the effect of reversible ureteric obstruction on renal function.

Animals↗
PubMed1996

The glomerular filtration rate, effective renal plasma flow, and renal blood flow in the adult male chacma baboon (Papio ursinus).

The radionuclide determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) has been validated in man, but not in the primate. GFR, ERPF, and renal blood flow (RBF) were measured in a group of 12 adult male chacma baboons using radiopharmaceuticals. GFR was determined using 99mtechnetium-labelled diethylenetriamine-pentacetic acid. ERPF was measured with 131iodine-labelled hippuran. RBF, body surface area, and kidney weights were calculated using standard formulae. GFR was 49 +/- 11 ml/min and ERPF was 237.9 +/- 54.2 ml/min. Calculated RBF was 430.7 +/- 111.9 ml/min and 507.4 +/- 138.4 ml/min/100 g of renal tissue. The results are in agreement with those obtained using more laborious nonradioisotopic techniques such as para-aminohippurate (PAH) and creatinine clearance and could serve as baseline normal values in the adult male chacma baboon.

Animals↗
PubMed1996

Hepatobiliary kinetics of technetium-99m-IDA analogs: quantification by linear systems theory.

UNLABELLED: A compartmental model describing the extraction and disposition of 99mTc-acetanilidoiminodiacetic acid (IDA) compounds by the liver has been applied to 5 adult patients admitted for cholecystitis investigations and 29 jaundiced infants the majority of whom were clinically differentiable into neonatal hepatitic and biliary atretic groups. METHODS: In each case kinetic rate constants were calculated to describe hepatocyte extraction of 99mTc-IDA structural analogs from blood pool (k21) and subsequent elimination (k3) of this compound into biliary tract. Also modeled was the reverse-binding constant (k12) describing the return of such radiotracer to the systemic circulation and the blood fraction (f) which accounted for the composite vasculature forming a matrix in the liver. RESULTS: It was shown that these indices could be used to determine accurate compartmental mean residence times (MRT(c)s) for each patient by correlation with values obtained by deconvolutional analysis and independent measurement of leading edge parenchymal transit times. For the adult patients the following indices, typical of good hepatocyte function, were derived: k21 = 0.933 +/- 0.488 min-1, k12 = 0.0277 +/- 0.0340 min-1, k3 = 0.1610 +/- 0.0531 min-1, f = 0.3519 +/- 0.3048 and MRTc = 11.19 +/- 3.13 min. Analysis of the pediatric group revealed no significant differences in their respective MRT(c)s. However, significant differences in the extraction (p < 0.01) and excretion (p < 0.001) coefficients were prominent. CONCLUSION: This method can be applied to provide accurate and meaningful intercompartmental rate parameters and MRT(c)s for adults, nonobstructed and obstructed infants.

Aged↗
PubMed1996

Is severe left ventricular dysfunction a contraindication to participation in an exercise rehabilitation programme?

OBJECTIVE: To evaluate the effects of an exercise training programme on patients with chronic left ventricular dysfunction. DESIGN: Intervention, before and after the trial. SETTING: Johannesburg Cardiac Rehabilitation Centre, a phase III community-based cardiac rehabilitation facility. PATIENTS: A consecutive sample of 28 patients who were recovering from acute myocardial infarction and who had a left ventricular ejection fraction of 30% or less. Twenty two patients completed the exercise training programme. INTERVENTION: A medically supervised exercise training programme of 6 months' duration. Type of exercise: walking, jogging or cycling. Intensity: 65-85% of the patient's maximal heart rate achieved during treadmill testing. DURATION: 30-45 minutes. Frequency: 3 times a week. Patients who attended fewer than 60% of all prescribed sessions were considered drop-outs. MAIN OUTCOME MEASURES: Haemodynamic, left ventricular function and effort tolerance parameters before and after training. RESULTS: Patients who completed the exercise training programme showed a significant improvement in maximal exercise capacity and a significant reduction in their cardiovascular demands during submaximal exercise. Peak oxygen consumption was increased by 12% after training (19.4 +/- 3 v. 21.8 +/- 4.8 ml/kg/min; P < 0.05) and exercise time to exhaustion by 33% (527 +/- 171 v. 700 +/- 186 seconds; P < 0.001). The double product at the same submaximal workload was significantly reduced (214 +/- 52 v. 194 +/- 44 beats/min x mmHg x 10(2); P < 0.05). These benefits were achieved without any adverse effects on resting (25.4 +/- 5 v. 28.5 +/- 7.9%; P < 0.05) or exercise (27.3 +/- 7.7 v. 29.9 +/- 9.5%; P > 0.05) left ventricular ejection fraction. CONCLUSIONS: Our results show that patients with chronic left ventricular dysfunction can benefit from an exercise training programme and that those benefits can be achieved without risk of further deterioration in left ventricular function. Physical training constitutes another therapeutic option which could be added to the comprehensive management of these patients.

Adult↗
PubMed1994

Effect of moderate dietary protein restriction on the progression of overt diabetic nephropathy: a 6-mo prospective study.

To assess whether moderate dietary protein restriction can delay the progression of overt diabetic nephropathy, 22 subjects with insulin-dependent diabetes mellitus were randomly assigned to an unrestricted protein diet (> 1.6 g.kg body wt-1.d-1) or a moderately protein-restricted diet (0.8 g.kg body wt-1.d-1) and followed prospectively for six mo. Direct isotope methods were used to assess renal function. Protein intake was assessed by measurement of urinary urea nitrogen. The two groups were well-matched for age, sex, duration of diabetes, glycemic control, blood pressure, and degree of renal insufficiency. Patients consuming the unrestricted protein diet (n = 11) showed a progressive decline in glomerular filtration rate of 1.3 mL.min-1.mo-1 with no change in proteinuria. Patients consuming the moderately protein-restricted diet showed a marked decrease in the degree of proteinuria (2.15-1.13 g/d, P = 0.036) and a stabilization of glomerular filtration rate. This occurred independently of changes in blood pressure or glycemic control. Moderate dietary protein restriction can ameliorate progression of overt diabetic nephropathy.

Adult↗
PubMed1994

Gallium scintigraphy in the diagnosis and total lymphoid irradiation of Takayasu's arteritis.

Takayasu's arteritis (TA) in children causes appreciable morbidity and mortality, predominantly as a result of the complication of renovascular hypertension (RVH). Ten children with TA, complicated by RVH, were treated at our centre over the past decade. An initial raised erythrocyte sedimentation rate (ESR) and a purified protein derivative greater than 15 mm were present in every case. More recently, gallium scintigraphy has been used to demonstrate sites of active inflammation in affected vessels (3/4 patients) which became negative after total lymphoid irradiation (TLI). The latter was used in the last 6 children, and appeared to be effective in controlling disease activity as evinced in the normalisation of their ESRs and negative findings on gallium scintigraphy (in all 3 patients with prior active inflammation). Because of vascular damage caused by the vasculitic process, surgical intervention is often required to improve organ perfusion, particularly of the kidney/s. Renal autografting (or allografting) seems preferable (6/11 kidneys functional) to renal bypass grafting (5/5 kidneys clotted). Patient survival improved when TLI was used in addition to standard surgical and medical therapy; this included steroids and antituberculous therapy with TLI, and steroids and cyclophosphamide in the two relapses. Five of 6 patients treated with TLI were alive after 32-54 months' follow-up, while 4 patients who received standard medical and surgical therapy but not TLI all died within 18 months of diagnosis. Gallium scintigraphy is a helpful diagnostic tool in assessing vasculitic activity in TA; TLI is an important mode of immunosuppression, but still needs to be compared with cyclophosphamide as the major immunosuppressive.

Child↗
PubMed1991

The value of estrogen and progesterone receptor determinations in advanced breast cancer. Estrogen receptor level but not progesterone receptor level correlates with response to tamoxifen.

Four hundred fifteen patients with metastatic breast cancer with known hormone receptor status received primary treatment with tamoxifen. Measured values for the estrogen receptor (ER, i.e., with estrogen binding) followed a continuous distribution (range, 3 to 1000 fmol/mg of protein). These values correlated positively with age. The response to treatment with tamoxifen correlated with the ER level, with response rates of approximately 80% when the ER level was greater than 30.1 fmol/mg of protein. Two hundred eighteen (218 of 415, 52%) patients had progesterone receptor (PR) values greater than 10 fmol/mg. The PR positivity correlated with the ER level. Patients with PR levels greater than 10 fmol/mg of protein (124 of 226, 55%) had a significantly higher response rate than those with values less than 10 fmol/mg of protein (45 of 189, 24%). However, in a multivariate analysis including both receptor levels, age, site, and number of metastases, only the ER level was significant in predicting the response to treatment with tamoxifen. A quantitative estimation of the ER level thus is the best predictor of response to hormonal treatment with tamoxifen for advanced breast cancer.

Adult↗
PubMed1990

Role of pyloroplasty in the retrosternal stomach: results of a prospective, randomized, controlled trial.

A prospective, randomized, controlled trial comparing clinical outcome and emptying of a solid meal from the retrosternal stomach, with and without pyloroplasty is described. Forty consecutive patients with oesophageal cancer undergoing retrosternal gastric reconstruction of the oesophagus were studied. In 20 patients the pylorus was left intact (group 1) and 20 patients underwent an Aust pyloroplasty (group 2). Nine patients in group 1 suffered postoperative symptoms of gastric stasis compared with only one patient in group 2 (P = 0.0106). Three patients in group 1 died from aspiration pneumonia before discharge from hospital. A gastric emptying test was performed on 24 patients between 1 and 3 months after surgery. By this time, most survivors had recovered from symptoms attributed to gastric stasis and no significant difference in gastric emptying could be demonstrated between the two groups. Selection of patients, a wide range of emptying times and improvement in gastric emptying on follow-up may explain the lack of correlation between postoperative symptomatology and the gastric half-emptying times. A pyloroplasty is advised to prevent the potentially lethal effects of gastric stasis in the early postoperative period following retrosternal reconstruction of the oesophagus.

Adult↗
PubMed1989

The role of membranous obstruction of the inferior vena cava in the etiology of hepatocellular carcinoma in Southern African blacks.

Membranous obstruction of the inferior vena cava has been incriminated as a risk factor for hepatocellular carcinoma in South African Blacks and in Japanese. However, the frequency with which this anomaly is found in patients with hepatocellular carcinoma, and hence its numerical importance as an etiological association of the tumor, has not been ascertained. Using radionuclide and contrast venography as well as necropsy and laparotomy examination, we investigated 162 unselected southern African Blacks with hepatocellular carcinoma together with appropriate controls for the presence of membranous obstruction of the inferior vena cava. Membranous obstruction of the inferior vena cava was detected in six of 162 (3.7%) hepatocellular carcinoma patients, compared with one of 279 subjects (0.36% p = 0.011) dying a violent death, none of 55 patients (p = 0.169) with malignant disease other than hepatocellular carcinoma and eight of 150 patients (5.3%; p = 0.336) being investigated for conditions which might have been associated with membranous obstruction of the inferior vena cava. Six of the 15 individuals (40%) found to have membranous obstruction of the inferior vena cava had concomitant hepatocellular carcinoma, confirming that membranous obstruction of the inferior vena cava constitutes a risk factor for the development of the tumor. However, only a very small proportion of hepatocellular carcinoma patients have this abnormality, so that it is a minor causal association of the tumor only.(ABSTRACT TRUNCATED AT 250 WORDS)

Black People↗
PubMed1989

Intravenous magnesium sulfate inhibits catecholamine release associated with tracheal intubation.

The effects of pre-treatment with 60 mg/kg body weight magnesium sulfate intravenous on cardiovascular responses and catecholamine release associated with tracheal intubation were measured in 15 normal patients and in 15 saline solution pre-treated controls. Magnesium pre-treatment increased heart rate by 13 +/- 3.9 beats/minute. After intubation, heart rate was unchanged in the magnesium group at 107.3 +/- 3.6 beats/minute but increased in the control group to 120.9 +/- 4.6 beats/minute (P less than 0.05). Systolic blood pressure increased after intubation from 106.8 +/- 3.1 to 121.0 +/- 4.4 mm Hg in patients given magnesium and from 106.4 +/- 3.12 to 145.1 +/- 5.6 mm Hg in the control group (P less than 0.05). Norepinephrine levels increased from 297.3 +/- 20.9 pg/ml to a peak of 532.5 +/- 30.1 pg/ml 2 minutes after intubation in the magnesium group. In controls, norepinephrine levels increased from 273.3 +/- 39.1 mg/ml to 944.6 +/- 68.7 pg/ml (P less than 0.05 for differences between groups). Epinephrine levels were unchanged from baseline after magnesium but in controls increased from 113.9 +/- 19.5 to 279.6 +/- 92.3 pg/ml (P less than 0.05). We conclude that magnesium sulfate attenuates the catecholamine mediated responses after tracheal intubation.

Adult↗
PubMed1988

The use of radionuclide venography in the differential diagnosis of inferior vena caval obstruction.

In using radionuclide imaging of the inferior vena cava (RIVC) to investigate the prevalence of membranous obstruction of the inferior vena cava (IVC) in patients with hepatocellular carcinoma, it was necessary first to determine if this technique would distinguish membranous obstruction of the IVC both from other causes of IVC obstruction likely to be encountered in these patients and from the picture obtained with severe ascites. RIVC readily distinguished an obstructed from a normally patent IVC. However, membranous obstruction of the IVC could not in most instances be differentiated from extrinsic compression of the IVC by an enlarged tumourous liver, occlusion of the lumen of the IVC by tumour, or the effect of severe ascites. In a proportion of the patients with membranous obstruction of the IVC, flow of the radionuclide through large superficial collateral vessels was seen, enabling this diagnosis to be made with confidence. Thus, if RIVC shows the IVC to be obstructed or if severe ascites is present, contrast venography will usually be necessary to determine the nature of the obstructing lesion.

Ascites↗
PubMed1987

Radioisotopic flow scanning for portal blood flow and portal hypertension.

The use of a simple, noninvasive, isotope scanning technique for the determination of relative portal blood flow and detection of portal hypertension is described. Using this technique the presence of portal hypertension was demonstrated in seven of nine patients known to have elevated portal venous pressure. By contrast, esophageal varices were demonstrated in only five of these patients, illustrating the potential value of the method. Furthermore, this technique has been adapted to the study of portal blood flow in patients with myeloproliferative disorders with splenomegaly but without disturbances in hepatic architecture. Results demonstrate that the high relative splenic flow resulting from the presence of splenomegaly may in turn be associated with elevated relative portal blood flow and portal hypertension. The theoretic reasons for the development of flow-related portal hypertension and its relationship to splenic blood flow are discussed.

Blood Flow Velocity↗
PubMed1987

Aromatisation of androstenedione by human breast cancer tissue: correlation with hormone receptor activity and possible biologic significance.

The conversion of 1 beta [3H] androstenedione to estrone in the presence of NADPH by breast cancer homogenates was assessed in tumors from 35 subjects together with estrogen and progesterone receptor concentration. Breast cancers from post menopausal women had significantly higher aromatase activity than those from premenopausal women. Although in many instances the local production of estrogens was sufficient to the capable of exerting a biologic effect, there was, however, no correlation with tumor estrogen or progesterone receptor content. Further studies of the biological significance of tumor aromatisation will depend on direct observation of tumor aromatase and response to suitable doses of aromatase inhibitors.

Androstenedione↗