Biomedical subjects

R D Levy

Publications and source records attributed to R D Levy.

116 records · Page 7Linked to original sources

PubMedDate not supplied

The effect of pH on chemiluminescence of different probes exposed to superoxide and singlet oxygen generators.

The compromised optima for high intensity chemiluminescence (CL), using superoxide generators, were all above pH 9.0 for the CL probes luminol and lucigenin. With luminol the optima were at pH 9.0 and 9.4 for the generators KO2 and hypoxanthine/xanthine oxidase (HX/XO), respectively. Lucigenin, with the same generators, produced optima at pH 9.5 and 10.0, respectively. The probe methyl-Cypridina-luciferin analogue (MCLA) produced optima closer to neutral pH, which is preferred for physiological assessments. MCLA had optima at pH 6.0, 8.7 and 9.5 with KO2 and with HX/XO optima at pH 4.8, 6.0, 7.0 and 8.7. When CL was assessed at physiological pH, MCLA observed superoxide radicals with a sensitivity of 100- and 330-fold more than luminol or luicigenin respectively. For singlet oxygen, the sensitivity of MCLA at this pH was 45- and 5465-fold more than for the said probes respectively. H2O2 did not elicit CL between pH 4 and 9.5 with any of the probes and did not influence the production of superoxide or singlet oxygen when co-assessed. Therefore CL could only be obtained when enzymes were used as converters. The optima for the enzyme-conversion system horseradish peroxidase (HRP)/H2O2, and luminol, were at pH 8.0 and 9.2. Lucigenin and HRP/H2O2 also had a biphasic CL profile with optima at pH 7.4 and 9.6. MCLA and HRP/H2O2 had five optima, with the major ones at pH 6.1 and beyond 10. The optima for the myeloperoxidase/H2O system were at 8.6 and beyond 10.0 when luminol and 0.15 mol/L NaBr were used.

Free Radical Scavengers↗

PubMedDate not supplied

Pyloric exclusion in severe penetrating injuries of the duodenum.

This study comprises 74 patients with penetrating injuries of the duodenum. Sixty-three of these had sustained gunshot wounds, many of which were high velocity. The change in the incidence and the severity of the gunshot injuries within the last few years resulted in changes in the operative management of the duodenal wound with gradually improving results. When pyloric exclusion was added to the operative management of grade III duodenal injuries, the postoperative leakage rate was 12%. When only primary repair was done, the leakage rate was 43%. We suggest that pyloric exclusion be added to the treatment of most severe grade II and all grade III gunshot duodenal injuries. The adequacy of primary repair and pyloric exclusion in grade IV injuries requires further study.

Adult↗

PubMedDate not supplied

Management of combined penetrating cardiac and abdominal trauma.

This is a retrospective review of patients with combined penetrating cardiac and abdominal trauma. Clinical presentation patterns are described and a management strategy is outlined. The series comprises 25 patients. On the basis of the mechanism of injury and the prognosis, the patients were divided into two groups: 'low risk' (single high epigastric stab wound) and 'high risk' (multiple stabs, single or multiple gunshot wounds). There were six patients in the low-risk group. Their intra-abdominal injuries were moderately severe. None of this group died. There were 19 patients in the high-risk group. Three underwent emergency-room thoracotomy and died. Of the remaining patients, four underwent a thoracotomy first for cardiac tamponade or massive haemothorax and 12 underwent a laparotomy first because of massive haemoperitoneum. The mortality in this group was 63 per cent. It is essential to recognize the cardiac injury in low-risk patients; the cardiorrhaphy must be performed before the laparotomy. In high-risk patients, the sequence of operations depends on the clinical presentation. Obvious cardiac tamponade or massive haemothorax mandate a thoracic approach first, while severe hypovolaemic shock with a massive haemoperitoneum justifies the performance of a laparotomy first; a transdiaphragmatic pericardiotomy is useful, in these cases, before proceeding to median sternotomy.

Abdominal Injuries↗

PubMedDate not supplied

Reference values for a multiple repetition 6-minute walk test in healthy adults older than 20 years.

PURPOSE: To (1) identify greatest 6-minute walk distance (6MWD) from among several repetitions (best 6MWD) in a wide age range of healthy volunteers to develop reference values for the multiple repetition 6MWD, and (2) investigate the influence of demographics, anthropometrics, and habitual exercise activity on best 6MWD. METHODS: Four 6MWD were performed on the same day in a 20-meter corridor by 41 male and 38 female healthy volunteers ranging in age from 20 to 80 years. The greatest 6MWD by each subject from among four 6MWDs was the primary outcome measure. RESULTS: Eighty-six percent had their best 6MWD after the first walk; an average increase of 43 meters was observed from first to best 6MWD (P < 0.003). Best 6MWD averaged 698 +/- 96 meters and was inversely related to age (P < 0.001), directly to height (P < 0.001), and was greater in men than women (P < 0.0002). A regression model accounted for 41% of between-subject variability in best 6MWD (P < 0.00000001). In a subset of older subjects, predicted 6MWD significantly underestimated measured best 6MWD when reference values were used from another study where test familiarization was not provided, but this difference disappeared when value were used from the present and a third study where test familiarization was provided. CONCLUSIONS: The present study is the first to provide predicted 6MWD values performed with multiple repetitions and for subjects in the 20-40-year-old age range. Selection of appropriate predicted 6MWD values for interpretation of performance should be guided by subject age and degree of test familiarization provided.

Adult↗

PubMedDate not supplied

Recurrence of intravenous talc granulomatosis following single lung transplantation.

Advanced pulmonary disease is an unusual consequence of the intravenous injection of oral medications, usually developing over a period of several years. A number of patients with this condition have undergone lung transplantation for respiratory failure. However, a history of drug abuse is often considered to be a contraindication to transplantation in the context of limited donor resources. A patient with pulmonary talc granulomatosis secondary to intravenous methylphenidate injection who underwent successful lung transplantation and subsequently presented with recurrence of the underlying disease in the transplanted lung 18 months after transplantation is reported.

Biopsy↗

PubMedDate not supplied

[Pulmonary transplantation in Quebec].

Quebec performed the first lung transplantation in 1963 which was unsuccessful in term of survival rate at that time. Since 1985, as the advancement of knowledge of pulmonary pathologies and of surgical techniques, 18 heart lung transplantations and 30 lung transplantations have been performed.

Humans↗

PubMedDate not supplied

Exercise performance after lung transplantation.

Heart-lung, double lung, and single lung transplantation have been shown to be effective in the treatment of patients with advanced cardiopulmonary disorders. An overlap in indications occurs for the different procedures, and in many situations the factors that are important in selecting the best operation for a given patient have not been clearly elucidated. To determine whether the anticipated exercise capacity should be an important consideration in the selection of the optimal procedure for a given patient, we compared exercise performance in patients who had undergone the different lung transplantation procedures in the preceding year and were otherwise well. Eleven heart-lung, six double lung, and 16 single lung recipients and 28 control subjects underwent maximal symptom-limited incremental exercise tests using a cycle ergometer. At peak exercise, transplant recipients reached maximum oxygen uptakes in the range of 40% to 60% of predicted values; no significant differences existed between the means of the different transplant groups. Ventilatory factors did not appear to limit exercise in any group. The exercise responses in the transplant subjects were characterized by reduced aerobic capacity and diminished oxygen pulse, factors indicating abnormal cardiovascular performance. Our data indicate that moderate levels of exercise can be anticipated early after heart-lung, double lung, and single lung transplantation. In the absence of substantial differences in exercise capacity, other considerations would appear to be more important in guiding the selection of the optimal lung replacement procedure for an individual patient.

Adult↗

PubMedDate not supplied

Elevated reversible and irreversible lipid peroxidation in human oesophageal cancer.

BACKGROUND: Cancer of the oesophagus is the most common gastrointestinal malignancy in South African blacks. The aim of this study was to determine the reversible and irreversible lipid peroxidation in cancer of the oesophagus; a feature that has not been assessed before in this or other cancer tissue. METHODS: Biopsies and plasma from 39 patients with cancer of the oesophagus and 22 biopsies and plasma from non-cancer patients were analysed for the irreversible lipid peroxide product malondialdehyde (MDA) and other reversible lipid peroxide products (LPO) by the thiobarbituric acid-reactive substances (TBARS) method. RESULTS: The mean (+/- SEM) for MDA in plasma from normal patients was 1.697 (0.149), and for cancer patients 4.23 (0.417) nmol MDA/ml. The tissue MDA for normal patients was 0.807 (0.154), and for cancer patients 2.530 (0.379) nmol MDA/mg protein. The mean (+/- SEM) for LPO in plasma from normal patients was 1.929 (0.281), and for cancer patients 12.607 (1.451) nmol MDA/ml. The tissue LPO for normal patients was 2.957 (0.306), and for cancer patients 16.320 (1.868) nmol MDA/mg protein. All the MDA and LPO values for cancer patients were significantly elevated (p < 10(-4)). In oesophageal cancer 85% of the lipid which was peroxidized, was of the reversible type. CONCLUSIONS: This elevated reversible LPO levels in plasma and oesophageal tissue of cancer patients support the notion that the oxy-radicals in cancer are not under proper metabolic control. Therefore, human oesophageal cancer does not progress to self regression or destruction but rather to more mutagenic changes probably due to high reversible lipid peroxidations.

Black or African American↗