shukoor65/lab-rag-model huggingface dataset:
Early experience with mitral valve reconstruction for mitral insufficiency. Mitral valve repair for mitral regurgitation has been reported to have more favorable early and late results than mitral valve replacement. From July 1985 through July 1990, 63 patients have undergone valve repair at Good Samaritan Hospital. Twenty-two men and 41 women whose ages ranged from 34 to 81 years (mean 67.9 years) were treated. Twenty-eight patients were in New York Heart Association functional class III or IV. Twelve (19%) had undergone prior cardiac surgery. Isolated valve repair was performed in 18 patients. Valve repair was combined with coronary artery bypass grafting, other valve procedures, or aneurysm resection in the remainder (71%). Two patients (3%) died while in the hospital, and four deaths (one valve-related) occurred after discharge. Leaflet resection for ruptured chordae was done in 24 patients (38%), chordal shortening in 5 patients (8%), and leaflet transposition in 2 patients. Rigid ring annuloplasty (Carpentier) was performed in 62 patients. Eight patients required mitral valve replacement at the same operation because of unsatisfactory valve repair. Results of valve repair evaluated by echocardiography at discharge show that 48 patients (88%) are free of significant regurgitation. Follow-up to date reveals that all surviving patients who underwent valve repair have clinically improved and are stable. Four of five patients with moderate mitral regurgitation are currently asymptomatic. There have been two valve-related late failures requiring reoperation. Based on this early experience, we conclude that valve repair compared with mitral valve replacement has a low operative mortality with good early results. Continued efforts to preserve native mitral valve function in the presence of mitral regurgitation appear justified.
CO2 laser-induced pain-related somatosensory evoked potentials in peripheral neuropathies: correlation between electrophysiological and histopathological findings. Pain-related somatosensory evoked potentials (pain SEPs) following CO2 laser stimulation as well as conventional electrically stimulated SEPs (electric SEPs) were examined in 10 patients with peripheral neuropathies in whom the histopathological examination of the sural nerve was done. Results of pain SEPs showed a positive relationship with clinical impairment of pain sensation and densities of small myelinated fibers of the sural nerve. In contrast, results of electric SEPs showed a positive relationship with clinical impairment of deep and tactile sensations and with densities of large myelinated fibers of the sural nerve. Therefore, pain SEPs are considered to be generated by ascending signals mediated through nociceptive receptors and A delta fibers. The pain SEP is only one noninvasive and objective method currently available to investigate a physiological condition of the sensory pathway responsible for pain sense, and is especially useful when combined with the conventional electric SEPs.
Secretagogue response of azaserine-induced rat pancreatic acinar tumors in vivo. This study investigates digestive and lysosomal enzyme secretion of azaserine-induced pancreatic acinar carcinomas in response to cholecystokinin in rats. After 15-20 months of treatment, 95% of the animals developed pancreatic acinar carcinomas encompassing more than 90% of the tissue. In anesthetized rats basal trypsin output was significantly elevated in the tumor group despite diminished fluid secretion. There was a linear correlation between tumor size and basal amylase and trypsin secretion. Intravenous infusion of cholecystokinin (25 IDU.kg-1.h-1) induced a significantly lower secretion of fluid per gram pancreas, as well as decreased amylase and trypsin output, in the tumor group compared with the control group. Plasma amylase and lipase levels were significantly elevated in the tumor group under both basal and stimulated conditions. The output of the lysosomal enzymes beta-D-glucuronidase and alpha-D-glucosidase was significantly increased in the tumor group under background secretin infusion. Additional cholecystokinin infusion caused a sharp increase in glucuronidase output in this group with only minimal increase in controls. Glucosidase output increased similarly in both groups. Amylase, lipase, and trypsin tumor tissue concentrations were markedly reduced by 85%, 90%, and 87%, respectively. It was concluded that the decreased secretory response of digestive enzymes may result from decreased synthesis, lowered storage capabilities, and/or a decreased/increased responsiveness to cholecystokinin. Increased glucuronidase secretion may reflect an augmented cell turnover of malignant tissue.
Factors affecting the measurement of cholesterol nucleation in human gallbladder and duodenal bile. The study of cholesterol gallstone disease would be facilitated if the nucleation time of cholesterol crystals could be measured in duodenal bile and was correlated with nucleation occurring in vivo. Therefore, our aims were to determine (a) if nucleation time could be measured in duodenal bile, (b) the effect of bacteria, phospholipase, protease, and dilution on the measurement of nucleation time, and (c) the ability of nucleation time of duodenal bile to reflect changes occurring in vivo that promote the formation of gallstones and, therefore, the potential usefulness of nucleation time in predicting and studying the formation of gallstones. Gallbladder bile was obtained from 27 patients undergoing elective cholecystectomy and 19 patients undergoing diagnostic duodenal biliary drainage. Among the 14 bile samples collected by drainage that nucleated within 21 days, mean nucleation time was 6.3 +/- 2.8 days. The addition of inhibitors of phospholipase or protease prolonged nucleation time slightly. Bacteria were cultured from one bile sample at the time of collection and five samples at the time of nucleation. The addition of antibiotics had no effect on nucleation time. Dilution of bile collected at cholecystectomy to the concentration of duodenal bile prolonged nucleation time. In 4 of 5 obese patients receiving a very low calorie diet and predisposed to gallstones, the nucleation time in duodenal bile shortened, and the shortest nucleation times were associated with the formation of cholesterol crystals in vivo. Thus, measurement of nucleation time in duodenal bile may be useful in predicting and studying the formation of cholesterol gallstones.
Vascular reactivity after balloon angioplasty in an atherosclerotic rabbit. Alterations in vessel wall reactivity (VR) at or adjacent to the dilation site after balloon angioplasty (BA) may vary according to the inflation protocol and the time after angioplasty and may influence outcome. In 64 atherosclerotic rabbit femoral arteries, we evaluated VR after BA with intravenous ergonovine (ERGO) (40 micrograms/min for 5 minutes) and intra-arterial nitroglycerin (NTG) (2,500 micrograms single bolus) 24-72 hours and 28 days after BA. Comparisons were made with atherosclerotic, nonangioplastied, age-matched controls. BA was standardized to three 1-minute inflations, each 1 minute apart. For each balloon size, 2.5- (appropriate size) or 3.0-mm (oversized) vessels were allocated to either 5 or 10 atm inflation pressure. For the analysis, four groups were compared: Group 1, 3.0/5; group 2, 3.0/10; group 3, 2.5/5, and group 4, 2.5 mm/10 atm. Angiographic diameters were measured at, proximal, and distal to the lesion at baseline, 10 minutes after ERGO, and 5 minutes after NTG. Angiograms were measured with electronic calipers by two blinded observers. All segments of control vessels vasoconstricted to ERGO and vasodilated to NTG (p less than 0.05 versus baseline), indicating a normal response. At 24-72 hours after dilatation, the angioplasty sites for all inflation pressure/balloon size combinations were not responsive to either ERGO or NTG. All segments distal to the dilatation sites vasoconstricted to ERGO and dilated to NTG (p less than 0.05 versus baseline), indicating a normal response. Proximal segments of vessels dilated with a 2.5-mm balloon (appropriate size) responded positively to both stimuli (p less than 0.05). Those vessels dilated with a large balloon (3.0 mm) were nonreactive in the segment proximal to the angioplasty site. Twenty-eight days later angioplasty sites dilated with a 2.5-mm balloon (appropriately sized) regained reactivity; however, segments dilated with a large balloon (3.0 mm) remained unresponsive. All proximal segments, including those from vessels dilated with a large balloon, reacted positively. All distal segments reacted appropriately. Restenosis rates were not different between the over- and appropriately sized balloon groups. These data demonstrate that immediately after angioplasty, vessels lose reactivity at the dilatation site. Those vessels dilated with the smaller-size balloon (2.5 mm) regained reactivity. For large balloons, reactivity is not regained at 28 days. For segments proximal to the site of dilatation, transient loss of reactivity is seen only when a large balloon is used. Thus, acute closure originating at the site of dilatation is not a result of spasm.(ABSTRACT TRUNCATED AT 400 WORDS).
Cell type-dependent effect of phospholipid and cholesterol on bile salt cytotoxicity. The effect of phosphatidylcholine and cholesterol on bile salt-induced cytotoxicity was investigated. Experiments were performed in both human erythrocytes and cultured CaCo-2 cells, a model system for gastrointestinal epithelium. Hemolysis induced by 50 mmol/L sodium-taurocholate was reduced by both lecithin and cholesterol in a concentration-dependent manner. Cholesterol was 10 times more effective than phosphatidylcholine. Addition of only small amounts of the sterol to phosphatidylcholine/taurocholate solutions eliminated all cytotoxicity. The protective influence of cholesterol is probably mediated through a direct effect on the membrane. Incubation of erythrocytes with a cholesterol/taurocholate mixture greatly increased the cholesterol content of the membrane. With respect to sensitivity to bile salts and the protective effect of lecithin, CaCo-2 cells behaved very similar to erythrocytes. However, cholesterol failed to have any cytoprotective effect when used in combination with taurocholate or phosphatidylcholine/taurocholate solutions. Interestingly, at relatively high concentrations of cholesterol (cholesterol saturation index greater than 1.0), the sterol even increased cytotoxicity. This correlated with a cholesterol-induced shift of phosphatidylcholine from micelles to vesicles, which normally occurs in supersaturated model and human bile. The different sensitivity of the two cell types to the effect of cholesterol on bile salt damage might be caused by the difference in lipid membrane composition. In conclusion, CaCo-2 cells represent a physiologically more relevant model system to study bile cytotoxicity than erythrocytes. When extrapolated to gallbladder epithelial cells, these results could be relevant for the pathogenesis of gallstone disease. The increased cytotoxicity might be the signal by means of which supersaturated bile induces mucin hypersecretion by gallbladder epithelial cells.
Role of the sarcolemma in triggered propagated contractions in rat cardiac trabeculae. We have recently described that after contractions propagate through multicellular cardiac muscle preparations. These propagating contractions are triggered in damaged regions of rat right ventricular trabeculae during relaxation of electrically stimulated twitches. Propagation of triggered contractions has been attributed to calcium ions that diffuse along the preparation, causing calcium-induced calcium release from the sarcoplasmic reticulum in adjacent cells. In the present study we have investigated a possible role of the sarcolemma and delayed afterdepolarizations (DADs) in the initiation and propagation of triggered propagated contractions (TPCs) in multicellular preparations. We studied whether 1) TPCs are accompanied by delayed sarcolemmal depolarizations, 2) such depolarizations mediate local contraction, and 3) an intact sarcolemma is required for propagation of contractions. TPCs that remained stable for prolonged periods of time could be induced by trains of 15 stimuli (2 Hz, 15-second intervals) at lowered temperature (19-21 degrees C) of the superfusing Krebs-Henseleit medium and a [Ca(2+)]o of 1.0-1.5 mM. Although TPCs could be induced at 38 degrees C and a [Ca2+]o of 3.0-4.0 mM, they disappeared within 10 minutes. Force was measured with a silicon strain gauge; length and shortening of sarcomeres were measured at two sites of the muscle using laser diffraction techniques. Membrane potential was measured with flexible microelectrodes. Saponin was used to selectively render the sarcolemma permeable to small ions and molecules. Propagation velocity of TPCs in intact trabeculae varied from 1.7 to 13.4 mm/sec at 19-21 degrees C. TPCs were accompanied by DADs that could reach threshold and induce triggered arrhythmias. Changes in latency, duration, and force of TPCs, induced by changing [Ca(2+)]o or the number of conditioning stimuli, were closely matched by changes in latency, duration, and amplitude of DADs; DADs consistently preceded TPCs, on average by 60 msec. Local heating of the muscle, by applying a current through an insulated platinum wire (diameter 100 microns) that touched the muscle, interrupted propagation of TPCs reversibly. DADs were, in the absence of a local contraction, still recorded distal to the heated site. In muscles that were treated with saponin and exposed to solutions approximating the intracellular milieu, spontaneously occurring local contractions that propagated in both directions (at velocities of 70-200 microns/sec) were elicited at a bathing calcium concentration of approximately 0.6 microM. Below this threshold, propagated contractions could be triggered by pressure ejection of a calcium-containing solution from a microelectrode positioned close to the trabecula.(ABSTRACT TRUNCATED AT 400 WORDS).
Scheduling of revaccination against hepatitis B virus Studies have shown that to maintain protection against infection after a primary course of hepatitis B immunisation, revaccination can be scheduled on the basis of an anti-hepatitis B virus surface antigen (anti-HBs) titre obtained 1 month after the booster dose. However, schemes which require post-booster testing may present practical difficulties. We applied a random-effects regression model to data from 118 Senegalese infants given three injections of hepatitis B vaccine about 6 weeks apart and a booster injection at 13 months, and show that revaccination can be scheduled on the basis of an anti-HBs titre recorded at the time of the booster dose. We also show that titre-at-booster is no less accurate in predicting future titre than 1-month post-booster titre. In several other studies the post-booster decline in anti-HBs conforms to the same mathematical description, indicating the generality of our findings.
Effect of antireceptor antibodies in dilated cardiomyopathy on the cycling of cardiac beta receptors. A substantial proportion of patients with dilated cardiomyopathy have circulating autoantibodies directed against the cardiac beta-adrenoceptor. These antireceptor antibodies inhibit both ligand binding to membrane beta-receptors and isoproterenol-sensitive adenylate cyclase. The functional consequences of antibody-receptor interactions were further studied by examining their influence on beta-adrenoceptor cycling. Sera from eight patients with cardiomyopathy induced a loss of beta-receptors from the surface of cardiac myocytes consistent with internalization. This loss was inhibited by concanavalin A, suggesting that receptor sequestration preceded internalization but was unaffected by the cytoskeleton inhibitors colchicine and cytochalasin. In cell-free preparations, serum-induced desensitization of beta-receptors was prevented by heparin but not the inhibitor of protein kinase A; this is consistent with a requirement for receptor phosphorylation by the beta-receptor kinase. In contrast to isoproterenol-mediated endocytosis, beta-receptors internalized under the influence of cardiomyopathic sera do not recycle to the plasma membrane. These results indicate that antireceptor antibodies in human dilated cardiomyopathy induced downregulation by interfering at several steps in the cycling of beta-receptors. These effects would contribute to the reported decline in beta-receptor responsiveness in cardiomyopathic myocardium.
Preliminary results in invasive bladder cancer with transurethral resection, neoadjuvant chemotherapy and combined pelvic irradiation plus cisplatin chemotherapy. Preliminary data are presented of a clinically feasible pilot study to select a significant subgroup of patients among those with muscle-invading bladder tumors for local cure and bladder preservation, while also to offer all patients the possibility of preventing the development of distant metastases. Transurethral debulking surgical resection was combined with neoadjuvant methotrexate, cisplatin and vinblastine chemotherapy plus 2 additional courses of cisplatin and 4,000 cGy. If tumor was found on cystoscopic re-evaluation by biopsy and for cytology after cisplatin and partial irradiation (4,000 cGy.) immediate cystectomy was advised. If tumor was not found consolidation by a radiotherapy boost to a total of 6,480 cGy. plus 1 additional course of cisplatin was given. Of 53 consecutive patients the planned treatment was completed in 42 (79%). With a median followup of 26 months (range 15 to 42 months), 72% of all entered patients were alive, 70% have not required cystectomy and 74% have not had distant metastases. Among the 42 patients who completed the planned protocol chemotherapy dose reductions were required in 39% for stomatitis, bone marrow depression and/or renal dysfunction. There were 2 serious complications but no treatment-related sepsis, deaths or significant renal dysfunction. Eight patients underwent immediate radical cystectomy because of positive biopsy and/or cytology results after 4,000 cGy., while 34 completed full chemotherapy and radiotherapy without any significant bladder or bowel injury. Of 42 patients 22 (52%) have maintained the bladder without any recurrence, and of those selected for full chemotherapy and radiotherapy this number increased to 65%. To date 12 patients have persistent or recurrent bladder tumors: 5 (15%) had invasive tumors treated by cystectomy and 7 (21%) had carcinoma in situ treated by intravesical therapy. The true success of this or other selective bladder-preserving treatments will require 3 to 5 years of followup to be confident that such treatment has sterilized the bladder of cancer. This feasibility study has been clinically practical, modestly well tolerated and encouraging for the significant proportion of patients with a sustained complete response and for the 70% over-all survival rate at 2 years. To evaluate critically the efficacy of methotrexate, cisplatin and vinblastine chemotherapy in the prevention of occult distant micrometastases and in increasing the rate of successful bladder preservation, in May 1988 we began a randomized phase 3 trial with and without neoadjuvant methotrexate, cisplatin and vinblastine chemotherapy.
Radical prostatectomy for localized prostatic carcinoma in the renal transplant patient. Three renal transplant patients had prostatic carcinoma after transurethral prostatectomy at 2 weeks, 2 months and 12 years following transplantation. One patient had stage A1 disease, while 2 had stage A2 prostatic carcinoma. All patients underwent radical retropubic prostatectomy and pelvic lymph node dissection. All patients had residual cancer in the radical prostatectomy specimen but none had nodal or capsular involvement. The surgical technique and rationale for management are discussed.
Angioedema: manifestations and management. Angioedema is characterized by localized swelling of sudden onset affecting the skin and/or mucous membranes. It can be classified into hereditary and acquired forms. Hereditary angioedema is a rare disease inherited as an autosomal dominant trait and caused by a deficiency of C1-esterase inhibitor. Acute attacks are life threatening and cannot be managed by antihistamines, corticosteroids, or adrenergic drugs. Prophylactic therapy is possible with danazol or stanozolol. Acquired angioedema includes nonhereditary C1-esterase inhibitor deficiency; idiopathic, allergic, and drug-induced forms; angioedema associated with lupus erythematosus and hypereosinophilia; and angioedema caused by physical stimuli. Treatment of these forms of angioedema depends on identifying and avoiding the cause, induction of tolerance, or symptomatic treatment with systemic antihistamines.
Altered inotropic responses in diabetic cardiomyopathy and hypertensive-diabetic cardiomyopathy. To understand the mechanisms of diabetic cardiomyopathy and the consequences of combined hypertension and diabetes, cardiac tissue responses to various inotropic agents were measured in experimental diabetes. Streptozotocin was injected into Wistar rats, spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats (WKYs). Six weeks after the injection diabetic rats showed a subsensitivity to beta adrenergic stimulation in ventricular tissue and a supersensitivity and hyper-responsiveness to Ca++ and alpha adrenergic stimulation (except in WKYs) in ventricular tissues and left atria. A supersensitivity to BAY K 8644 in SHR left atria and a hyper-responsiveness to verapamil in ventricular strips were also noted. These alterations may be due to a change in receptor number or to postreceptor alterations. Diabetic SHRs exhibited greater changes in several of the drug responses (responses to isoproterenol, phenylephrine and BAK 8644) were more hyperlipidemic and had a high mortality as compared with Wistar rats and WKY diabetics. These findings confirm that the combination of hypertension and diabetes results in greater cardiac pathology than is seen with either disease alone.
Isotopic study of the effects of platelets on development of intimal thickening in autologous vein grafts in dogs. The effects of platelets on the development of intimal thickening of arterially transplanted autologous vein grafts was investigated using canine poor run-off models. A new apparatus consisting of a shielding lead block to measure in vivo platelet adherence only on the intima of the vein graft was developed. In 23 dogs, 51Cr-labelled platelets (20 microCi/kg) were injected and isotope emission over the grafts was counted. Platelet adherence was expressed as the thrombocyte accumulation index (TAI), i.e. the ratio of counts over the graft under an abnormal flow condition in the poor run-off model to those over the graft under normal flow conditions of the contralateral leg. The TAI of the total graft (TTAI) was significantly high immediately and on the first and third days after implantation. The TAIs of the proximal (PTAI) and distal (DTAI) portions of the vein graft were also high at these same times. At 7, 10, 14 and 21 days, the TAI was almost equal to 1.0, a time at which endothelial regeneration was complete as confirmed by scanning electron microscopy. Thus, the prominent intimal thickening of arterially transplanted autologous vein grafts in dogs, induced under an abnormal flow condition, correlates well with the enhanced platelet adherence on the intima of the vein grafts in an early period after implantation.