123rc/medical_text huggingface dataset:
Studies of controlled reperfusion after ischemia. XXI. Reperfusate composition: superiority of blood cardioplegia over crystalloid cardioplegia in limiting reperfusion damage--importance of endogenous oxygen free radical scavengers in red blood cells. Postischemic damage is caused partially by oxygen free radical-mediated injury. This study will show that (1) crystalloid cardioplegia with room air oxygen is deleterious because it is devoid of free radical scavengers and (2) blood cardioplegia limits damage because it contains endogenous free radical scavengers in red blood cells. METHODS: Thirty-two dogs underwent 2 hours of ligation of the left anterior descending coronary artery followed by 20 minutes of regional blood cardioplegic reperfusion on bypass. Ten dogs received only the blood cardioplegic solution (containing its endogenous free radical scavengers); five received initial blood cardioplegia (5 minutes) with endogenous free radical scavengers (catalase and glutathione peroxidase) blocked by aminotriazole and N-ethylmaleimide, respectively; 12 received initial crystalloid cardioplegic solution oxygenated by room air (oxygen tension = 150 mm Hg); seven without and five with exogenous free radical scavengers (superoxide dismutase, catalase, coenzyme Q10); five received initial deoxygenated crystalloid cardioplegic solution (oxygen tension = 6 mm Hg); and five received deoxygenated crystalloid cardioplegic solution. RESULTS: Blood cardioplegia with endogenous free radical scavengers produced the best recovery of systolic shortening (69% systolic shortening) and resulted in the least histochemical damage (11% triphenyltetrazolium chloride nonstaining). The worst recovery and most damage occurred if blood cardioplegia was preceded by oxygenated crystalloid cardioplegia (3% systolic shortening, 48% triphenyltetrazolium chloride nonstaining; p less than 0.05 versus blood cardioplegia) or if free radical scavengers were blocked in the initial period of blood cardioplegia (3% systolic shortening, 41% triphenyltetrazolium chloride nonstaining; p less than 0.05 versus blood cardioplegia). Conversely, deoxygenation or supplementation of oxygenated crystalloid cardioplegic solution with exogenous free radical scavengers restored 60% systolic shortening (p less than 0.05 versus oxygenated crystalloid cardioplegia) and 54% systolic shortening (p less than 0.05 versus oxygenated crystalloid cardioplegia) and reduced damage to 34% and 21% (both p less than 0.05 versus oxygenated crystalloid cardioplegia). CONCLUSION: Blood cardioplegic solutions containing their own endogenous free radical scavengers are superior to crystalloid cardioplegic solutions, because they limit oxygen-mediated perfusion damage and restore contractile function. Initial crystalloid cardioplegic washout negates the salutary effect of blood cardioplegia. Exogenous free radical scavenger supplementation or deoxygenation of the cardioplegic reperfusate is necessary only if crystalloid cardioplegia is used.
Research and policy directions. Salt and blood pressure. The relation between dietary intake of sodium chloride and blood pressure levels remains controversial. The critical questions concern whether there is a susceptible subgroup at risk of elevated blood pressure because of sodium chloride consumption. If there is such a subgroup, what is its size and how can it be identified? Further clinical trials are needed to determine the long-term effects of sodium chloride reduction on blood pressure. The risk of disease, including stroke and coronary heart disease, is linear with blood pressure levels. A small change in blood pressure can have a relatively large impact on disease, even within the normal range of blood pressure.
Myocardial perfusion-contraction matching. Implications for coronary heart disease and hibernation. Experimental studies demonstrate that short-term regional perfusion-contraction matching, in which the energy demands of regional myocardial contraction are reduced to match the diminished myocardial substrate supply, occurs during states of low coronary blood flow under resting conditions and during exercise-induced ischemia. This phenomenon is rapidly reversible and appears to occur in several clinical settings. Sustained perfusion-contraction matching is observed in states of partial experimental ischemia of intermediate duration lasting several hours. This condition might be called short-term hibernation and resembles clinical conditions such as unstable angina pectoris or myocardial infarction with some residual perfusion in which the contractile defect can be improved by reperfusion provided the ischemia is not severe enough to cause transmural necrosis. Such experimental and clinical observations may or may not relate to the setting of regional dysfunction at rest in patients with chronic coronary heart disease, in whom manifestations of acute ischemia may be absent but improvement of wall motion abnormalities occurs after CABG or balloon angioplasty. This condition may constitute the hypothetical state of chronic myocardial hibernation, for which tentative evidence exists from metabolic and perfusion studies using PET. Whether such a condition of prolonged perfusion-contraction matching might be associated with adaptive processes that could allow its persistence for long periods without manifest ischemia remains to be investigated.
Electrocardiographic signal-averaging during atrial pacing and effect of cycle length on the terminal QRS in patients with and without inducible ventricular tachycardia. Electrocardiographic signal-averaging during sinus rhythm (61 to 99 beats/min) and atrial pacing (100 to 171 beats/min) were performed to determine the effect of heart rate on late potentials in 15 patients without (group 1) and 7 patients with (group 2) inducible sustained ventricular tachycardia (VT). In sinus rhythm (79 +/- 12 vs 77 +/- 12 beats/min, difference not significant), the duration of the low-amplitude signal less than 40 microV was longer in group 2 than group 1 (43 +/- 21 vs 26 +/- 8 ms, p = 0.034) and more patients had late potentials (57 vs 7%, p = 0.021), but QRS duration (121 +/- 32 vs 98 +/- 19 ms) and terminal voltage (33 +/- 33 vs 50 +/- 26 ms) were not significantly different. With atrial pacing in group 1 (128 +/- 16 beats/min), 3 patients developed a simultaneous decrease in terminal voltage and an increase in terminal QRS duration consistent with a late potential, but mean total and terminal durations were unchanged. Terminal voltage increased (50 +/- 26 to 59 +/- 40) but not significantly. With atrial pacing in group 2 (119 +/- 12 beats/min) all patients either had a late potential or developed a simultaneous decrease in terminal voltage and an increase in terminal QRS duration (p = 0.001 vs group 1). Root mean square (p = 0.001 vs group 1). Root mean square voltage decreased (33 +/- 23 to 22 +/- 23) and became significantly different from group 1 (p = 0.017). Mean QRS duration, root mean square terminal voltage and low-amplitude terminal QRS duration, however, were unchanged.
Lightning injury with lung bleeding in a tracheotomized patient. A 68-year-old man, who had undergone laryngectomy six months earlier, was struck by lightning and developed pulmonary hemorrhage. This was attributed to pulmonary barotrauma due to a lightning blast via his tracheostoma.
Effective doses of epidural morphine for relief of postcholecystectomy pain. Having previously established the effective dose of intrathecal morphine for relief of postcholecystectomy pain, we determined in this study the effective dose of epidural morphine for relief of postcholecystectomy pain in 154 patients given epidural injections of a placebo (group 1, n = 49), 2 mg morphine (group 2, n = 54), or 4 mg morphine (group 3, n = 51) intraoperatively mixed in 1.5% lidocaine. The percentage of patients who did not request an analgesic, 30 mg IM pentazocine, for relief of pain during the first 24 postoperative hours was significantly greater in groups 2 and 3 than in group 1. In patients who did need 30 mg IM pentazocine postoperatively, the number of times pentazocine was administered was also significantly greater in group 1 than in groups 2 and 3. The percentage of patients developing respiratory depression or vomiting in the first 48 postoperative hours was similar in the three groups. Based on the present data and those we previously reported for intrathecal morphine, we conclude that an epidural morphine dose of 2-4 mg and an intrathecal morphine dose of 0.06-0.12 mg are equipotent for relief of postcholecystectomy pain.
Leukotriene synthesis inhibition and receptor blockade do not inhibit hypoxic pulmonary vasoconstriction in sheep. Several lines of evidence suggest that leukotrienes may be mediators of hypoxic pulmonary vasoconstriction (HPV). However, the effect of leukotriene inhibition on HPV remains controversial. The present study investigated the effect of leukotriene synthesis inhibition and receptor blockade on HPV in the halothane-anesthetized sheep. After initial baseline measurements, the pulmonary pressor response to 15 min of global hypoxia (FIO2 = 0.13) was measured. A second set of baseline measurements was obtained and the sheep then received the combined cyclooxygenase/lipoxygenase inhibitor BW755C, the selective lipoxygenase inhibitor U60257, or the leukotriene receptor antagonist LY171883. Hemodynamic measurements were obtained after drug administration and during a subsequent hypoxic challenge (FIO2 = 0.13). Initial hypoxic challenge increased pulmonary artery pressure 68% and increased pulmonary vascular resistance 104%. Pulmonary hemodynamics after recovery from hypoxia were similar to initial baseline values. Drug administration had no significant hemodynamic effect. Hypoxic challenge after drug administration resulted in a pulmonary pressor response identical to the initial hypoxic challenge. Because leukotriene synthesis inhibition and receptor blockade did not alter the response to hypoxia, we conclude that leukotrienes are not obligatory mediators of HPV. A critical review of the literature supports a modulatory rather than an obligatory role for leukotrienes in HPV.
Analysis of antigen expression at multiple tumor sites in epithelial ovarian cancer. The question of whether the antigenic phenotype of human epithelial ovarian cancer varies in a given patient between the primary tumor and metastatic sites or among metastatic sites themselves is an important issue in planning potential therapeutic strategies for ovarian cancer. We have obtained tumor specimens from at least two separate sites during operations on 12 patients with epithelial ovarian cancer, and we have typed these specimens with a group of 18 monoclonal antibodies that react with cell-surface glycoprotein and carbohydrate antigens, including blood group antigens. Antibodies with relative specificity for malignant cells as well as those that detect more widely distributed epithelial antigens were used. A total of 31 specimens from 12 patients with advanced adenocarcinoma (8 serous, 3 undifferentiated, 1 endometrioid) of the ovary were studied, including fresh ascites cells in two patients. Frozen sections of tumor specimens were stained with the antibodies by the indirect immunoperoxidase technique and graded semiquantitatively. Little difference was seen in antigenic expression of tumors that were obtained from various sites in the same patient for either the epithelial cell markers or blood group markers. Intratumoral antigenic heterogeneity was seen, but this was generally quite consistent within a given patient's specimens. As anticipated, variations in antigen expression were seen among specimens from different patients. The antigenic phenotype of the tumor specimens in a given patient, as determined immunohistochemically by our group of antibodies, showed only minor variation among primary and metastatic sites.
Infantile CNS spongy degeneration--14 cases: clinical update. We studied 14 Arab infants with infantile spongy degeneration, 13 of whom were products of consanguineous marriages. They presented in infancy with macrocephaly, poor visual behavior or blindness, and axial hypotonia with appendicular spasticity. Brain CT and MRI showed diffuse symmetric leukoencephalopathy, even before neurologic symptoms. There were relatively normal EEGs. The visual evoked responses (P100) were either absent or delayed early in the course. The brainstem auditory evoked responses showed milder abnormalities, with loss of later components before the earlier ones. Deficient aspartoacylase activity in cultured fibroblasts or brain biopsy confirmed the diagnosis in all patients.
Blood rheology after cardiac valve replacement with mechanical prostheses or bioprostheses. Arterial thromboembolism is a serious complication in patients after heart valve replacement. Abnormalities in blood rheology may contribute to this complication. Therefore, the aim of this study was to compare various determinants of blood rheology in patients with substitute heart valves with those in healthy controls; furthermore, differences between patients with mechanical valves and those with bioprostheses should be investigated. The hemorrheologic determinants--fibrinogen, plasma viscosity, red cell aggregation, hematocrit and platelet aggregation--were studied in 92 patients with mechanical bileaflet valves, in 28 patients with bioprostheses and in 29 control subjects; the time since valve replacement was greater than or equal to 9 months. Fibrinogen, plasma viscosity, red cell and spontaneous platelet aggregation were found to be increased in all patients after heart valve replacement compared with normal subjects (fibrinogen: 348 +/- 87 vs 267 +/- 66 mg/dl, p less than 0.01; plasma viscosity: 1.71 +/- 0.1 vs 1.66 +/- 0.1 mPas, p less than 0.05; red cell aggregation: 9.9 +/- 2 vs 7.8 +/- 2 U, p less than 0.01; platelet aggregation: 22 +/- 15 vs 13 +/- 13%, p less than 0.01); among patients, fibrinogen, plasma viscosity and spontaneous platelet aggregation were higher in mechanical valves than in bioprostheses (fibrinogen: 359 +/- 95 vs 314 +/- 41 mg/dl, p less than 0.01; plasma viscosity: 1.72 +/- 0.1 vs 1.68 +/- 0.1 mPas, p less than 0.1; platelet aggregation: 23 +/- 15 vs 16 +/- 11%; p less than 0.05), whereas no difference could be found for red cell aggregation (9.7 +/- 2 vs 10.5 +/- 2%, p greater than 0.05).
Hemangiopericytoma of the sternum. Hemangiopericytoma of the chest wall is a rare tumor. We describe a patient with malignant hemangiopericytoma of the sternum who was treated with primary surgical resection and discuss the clinical, radiographic, and histologic features of the case. Surgical resection is the primary mode of therapy. High-dose radiotherapy and chemotherapy with a doxorubicin hydrochloride-containing combination may be warranted in certain cases.
Conservative management or closed nailing for tibial shaft fractures. A randomised prospective trial. We performed a prospective randomised trial on matched groups of patients with displaced tibial shaft fractures to compare conservative treatment with closed intramedullary nailing. The results showed conclusively that intramedullary nailing gave more rapid union with less malunion and shortening. Nailed patients had less time off work with a more predictable and rapid return to full function. We therefore consider that closed intramedullary nailing is the most efficient treatment for displaced fractures of the tibial shaft.
Nontuberculous mycobacterial infections of the skin. Report of fourteen cases and review of the literature. This study comprised 14 patients from whose skin nontuberculous mycobacteria were recovered. Most clinical manifestations were relatively nonspecific. Various histopathologic patterns were observed in 22 biopsy specimens. Recurrences were common and prolonged treatment was often necessary. Culture of tissue remains the definitive diagnostic procedure. Cutaneous lesions can be the first or only site of nontuberculous mycobacteriosis.
DNA ploidy pattern in rectal carcinoid tumors. The nuclear DNA pattern of 22 rectal carcinoids was determined by cytophotometry of paraffin embedded tissues. The results were compared with clinical as well as histopathologic features of the tumor. Three of the carcinoids with synchronous or metachronous metastasis had aneuploid DNA pattern, whereas 19 tumors with no metastasis showed diploid DNA pattern. No other single clinical or pathologic feature of the tumor could predict more accurately the malignant potential and the subsequent course of the rectal carcinoid. It is concluded that DNA aneuploidy in rectal carcinoid tumors is not so rare as indicated by earlier studies and that it is a factor of significant prognostic value.
Self-report of physical activity and patterns of mortality in Seventh-Day Adventist men. The Adventist Mortality Study provides 26-year follow-up through 1985 for 9484 males who completed a lifestyle questionnaire in 1960. The relationship of self-reported physical activity and all cause and disease-specific mortality was examined by survival analysis and with the Cox proportional hazards model, controlling for demographic and lifestyle characteristics. Moderate activity was associated with a protective effect on cardiovascular and all cause mortality in both analyses. In the Cox model, age-specific estimates of relative risk (RR) were obtained for several endpoints due to a significant interaction between level of physical activity and attained age (age at death or end of follow-up). This model permits calculation of the age at which the RR = 1.0, or the age at crossover of risk. For moderate activity, this age was 95.6 years (95% confidence intervals, 81.7-109.4 years) for all cause mortality and 91.5 years (95% confidence intervals, 79.0-104.0 years) for cardiovascular mortality. While the protective effect on mortality associated with moderate activity decreased with increasing age, it remained significant to the verge of the present life span.
Endothelial cell biology. The endothelium is not a passive blood-compatible lining for the containment of blood cells and plasma, but rather it is a metabolically active tissue that subserves a wide range of functions relating to vascular homeostasis. This article reviews the current understanding of endothelial cell biology in terms of the molecules and biochemical pathways involved. These regulate coagulant and thrombotic properties of the vessel wall, vascular tone, and hence blood flow and pressure; changes in solute permeability and leukocyte traffic during the generation of inflammatory and immune responses; and finally the processes of vessel growth and angiogenesis. The review concludes with a consideration of how these functional properties can be disturbed, and their possible consequences, in response to irradiation, intravascular contrast media, or angioplasty.
Selective uptake of toxic nucleoside (125IUdR) by resistant cancer. We report uptake of a thymidine analogue 125-Iodine-5-iodo-2'-deoxyuridine (125IUdR) by nude mice bearing human xenografts of choriocarcinoma or colonic cancer. When 125IUdR was given alone, uptake by intestinal tissues was 5-10 times greater than by the tumours as measured by tissue gamma counting. This ratio was reversed when hydroxyurea or cytosine arabinoside were used as inhibitors of ribonucleotide reductase and were given in combination with 5-fluorouracil or methotrexate to inhibit thymidine synthesis shortly before injecting 125IUdR. Counting the radioactivity in tissues removed 24 hours after 125IUdR gave tumour to highest normal tissue ratios of up to 15:1, but the corresponding nuclear grain counts, which is probably a more reliable indicator of selective uptake into DNA, were in excess of 100:1. The addition of unlabelled IUdR to the regimen only reduced the uptake of 125IUdR when given in relatively large amounts. For this approach to be exploited it is concluded that the tumour must be resistant at the cell level to the inhibitor of DNA synthesis either de novo or as a result of prior exposure to it. This inhibitor can then be used to block uptake of the potentially toxic nucleoside analogue by normal renewal tissues while it is taken up by the resistant cancer cells. By inhibiting synthesis of the corresponding normal nucleosides with inhibitors to which the cancer cells are not resistant, incorporation of the toxic analogues into tumour DNA was enhanced. Although 125IUdR is a convenient agent for exploring this approach and is highly cytotoxic when incorporated in DNA, the clinical potential of reverse role chemotherapy probably lies with the development of toxic non-radioactive nucleoside analogues.
Change in sympathetic activity before, during, and after dialysis-induced hypotension. During the hemodialyses of eight patients with end-stage renal failure, who often had sudden-onset dialysis-induced hypotension, catecholamine (CA) levels were measured in the ultrafiltrate obtained by a mini-filter placed in series upstream of the dialyzer. The water evaporation rate from the skin (reflecting the perspiration rate) was also monitored. Results showed a temporary elevation in CA levels in the ultrafiltrate before hypotension occurred. This rise did not continue for long, returning to baseline when hypotension actually occurred. The temporary elevation may reflect transient compensation by the sympathetic nervous system for the decrease in vascular wall tension. It was also found that there was considerable water evaporation from the skin during hypotension. Because sweat gland activity is reflexively modulated by the baroreceptor, perspiration after a drop in blood pressure may reflect the normal diminiution in baroreceptor activity.
Prolongation of ventricular refractoriness by class Ia antiarrhythmic drugs in the prevention of ventricular tachycardia induction. The effects of class la antiarrhythmic drugs (procainamide, quinidine) on the right ventricular effective refractory period (VERP) and intraventricular conduction time were assessed during serial invasive electrophysiologic studies for sustained monomorphic ventricular tachycardia (VT). In 47 patients with remote myocardial infarction, sustained VT was inducible by up to two extrastimuli after the basic drive at one of two basic cycle lengths at the right ventricular apex. With oral drug administration, sustained VT was no longer inducible (group I) in 27 patients but remained inducible (group II) in 20 with the same protocol. Class la drugs prolonged the VERP in both groups, but there was greater lengthening when drugs were effective (e.g., +32 +/- 14 msec in group I vs +12 +/- 19 msec in group II; p less than 0.005, basic cycle length 600 to 700 msec). Prolongation of the VERP by greater than 30 msec had an 88% positive predictive value for prevention of sustained VT induction. In all except one patient in group I, drugs prolonged the VERP such that the coupling intervals that had resulted in sustained VT induction under control conditions were no longer attainable. In contrast, conduction time through the ventricle (surface QRS duration) in sinus rhythm and during right ventricular pacing was prolonged similarly regardless of efficacy (e.g., +33 +/- 21 msec vs +27 +/- 27 msec at a cycle length of 400 msec). The presence of similar plasma levels of drug did not imply equivalent prolongation of the VERP in the two groups. These results suggest that greater prolongation of the VERP by oral procainamide or quinidine correlates with drug efficacy against VT induction and is a better predictor of drug effect than achievement of a "therapeutic plasma level.".