shukoor65/lab-rag-model huggingface dataset:
Endogenous prostaglandin endoperoxides and prostacyclin modulate the thrombolytic activity of tissue plasminogen activator. Effects of simultaneous inhibition of thromboxane A2 synthase and blockade of thromboxane A2/prostaglandin H2 receptors in a canine model of coronary thrombosis. We tested the hypothesis that simultaneous inhibition of TxA2 synthase and blockade of TxA2/PHG2 receptors is more effective in enhancing thrombolysis and preventing reocclusion after discontinuation of tissue plasminogen activator (t-PA) than either intervention alone. Coronary thrombosis was induced in 35 dogs by placing a copper coil into the left anterior descending coronary artery. Coronary flow was measured with a Doppler flow probe. 30 min after thrombus formation, the animals received saline (controls, n = 10); SQ 29548 (0.4 mg/kg bolus + 0.4 mg/kg per h infusion), a TxA2/PGH2 receptor antagonist (n = 8); dazoxiben (5 mg/kg bolus + 5 mg/kg per h infusion), a TxA2 synthase inhibitor (n = 9); or R 68070 (5 mg/kg bolus + 5 mg/kg per h infusion), a drug that blocks TxA2/PGH2 receptors and inhibits TxA2 synthase (n = 8). Then, all dogs received heparin (200 U/kg) and a bolus of t-PA (80 micrograms/kg) followed by a continuous infusion (8 micrograms/kg per min) for up to 90 min or until reperfusion was achieved. The time to thrombolysis did not change significantly in SQ 29548-treated dogs as compared with controls (42 +/- 5 vs. 56 +/- 7 min, respectively, P = NS), but it was significantly shortened by R 68070 and dazoxiben (11 +/- 2 and 25 +/- 6 min, respectively, P less than 0.001 vs. controls and SQ 29548-treated dogs). R 68070 administration resulted in a lysis time significantly shorter than that observed in the dazoxiben-treated group (P less than 0.01). Reocclusion was observed in eight of eight control dogs, five of seven SQ 29548-treated dogs, seven of nine dazoxiben-treated dogs, and zero of eight R 68070-treated animals (P less than 0.001). TxB2 and 6-keto-PGF1 alpha, measured in blood samples obtained from the coronary artery distal to the thrombus, were significantly increased at reperfusion and at reocclusion in control animals and in dogs receiving SQ 29548. R 68070 and dazoxiben prevented the increase in plasma TxB2 levels, whereas 6-keto-PGF1 alpha levels were significantly increased with respect to control and SQ 29548-treated dogs. Thus, simultaneous inhibition of TxA2 synthase and blockade of TxA2/PGH2 receptors is more effective than either intervention alone in this experimental model in enhancing thrombolysis and preventing reocclusion after t-PA administration.
Systemic hypertension alters vasomotor function in experimental vein grafts. Hypertension is an established risk factor for atherosclerosis, a disease that is important in the pathophysiology of vein graft failure. Hypertension can also alter arterial vasoreactivity. The vasomotor function and histologic characteristics of autogenous vein grafts in hypertensive rabbits were assessed in this study. Hypertension was induced in 13 male New Zealand white rabbits by use of the Goldblatt one clip two kidney method. The right carotid artery was divided and bypassed with the reversed right external jugular vein 7 days later in these animals and in 13 normotensive controls. Blood pressure and renal function were assessed serially, and all the grafts were harvested after 28 days. Three grafts in each group were examined by light microscopy. The responses of the remaining grafts to norepinephrine, histamine, serotonin, and angiotensin II were determined in vitro under isometric tension. Endothelium-dependent relaxation to acetylcholine and calcium ionophore (A23187) was assessed in precontracted grafts. The mean arterial pressure was significantly increased after the Goldblatt procedure was performed. Intimal hyperplasia was observed in both groups, but the grafts in the hypertensive groups showed increased adventitial and medial fibrosis and a reduced number of vasa vasora. The grafts in the hypertensive rabbits were hypersensitive to all agonists as indicated by a significant reduction in their median effective dose values, and their maximal responses to all agonists were also significantly reduced. No graft relaxed in response to acetylcholine, and whereas precontracted grafts in normotensive rabbits had a maximal relaxation of 24% +/- 6% of precontraction with A23187, this was absent in the grafts in the hypertensive rabbits. The results suggest that angiotensin-induced hypertension may adversely affect vein graft patency by inducing hypersensitivity to physiologically important agonists and reducing the effect of receptor-independent endothelium-derived relaxation on vasomotor tone.
Takayasu's disease and atherosclerosis. The aortic arch syndrome characterised by diminished or absent pulses in the arteries arising from the aortic arch has many etiologies, such as syphilitic aortitis, dissection of the aorta, atherosclerosis and Takayasu's arteritis. The diagnostic criteria of Takayasu's arteritis often do not mention histological investigations. We observed a case of an aortic arch syndrome, presenting as a classical case of Takayasu's arteritis but caused by a severe form of atherosclerosis.
Marginal ulcer following gastric bypass for morbid obesity. Four hundred twelve patients underwent gastric bypass for treatment of morbid obesity between 1981 and 1985 at the University of Florida Affiliated Hospitals. Thirty-four patients (8.2%) developed marginal ulcers, considerably higher than the 0-3 per cent ulcer occurrence commonly reported in the literature. Factors predisposing to ulcer formation include: (1) a large gastric pouch; (2) a vertically oriented pouch; and (3) staple-line dehiscence. Twenty-two of 34 patients (65%) with symptomatic marginal ulcers were noted to have staple-line disruption. Twenty-one of these patients (95%) eventually required operative therapy for their ulcers compared with four of 12 patients (33%) with an intact gastric staple line. Surgical therapy consisted of takedown of the Roux-en-Y limb with resection of the ulcer and gastrogastrostomy. Staple-line dehiscence is a significant etiologic factor in the development of marginal ulcer following gastric bypass and when present constitutes an indication for reoperation.
Inhibition of prostaglandin synthesis fails to prevent gallbladder mucin hypersecretion in the cholesterol-fed prairie dog Gallstone formation in the cholesterol-fed prairie dog is preceded by an increase in mucin secretion by the gallbladder epithelium, and mucin hypersecretion is believed to promote cholesterol gallstone formation by accelerating the nucleation of cholesterol monohydrate crystals. Some studies have suggested that gallbladder mucin hypersecretion is mediated by increases in gallbladder prostaglandin synthesis, but other observations are difficult to reconcile with this view. An organ culture technique was used to measure mucin secretion in normal prairie dog gallbladder in response to exogenous prostaglandins and agents that increased or decreased endogenous prostaglandin production. Incubation with indomethacin produced a concentration-dependent inhibition of endogenous prostaglandin synthesis with virtually complete inhibition at 10(-5) mol/L indomethacin. However, indomethacin had no effect on gallbladder mucin secretion at concentrations as high as 10(-5) mol/L, and significant inhibition of mucin secretion was only found at 10(-4) mol/L indomethacin, a concentration that also produced a significant increase in lactate dehydrogenase release from cultured explants. Incubation of gallbladder explants with the calcium ionophore A23187 significantly stimulated endogenous prostaglandin synthesis in a concentration-dependent manner, increasing synthesis of prostaglandins E and F to as much as 278% +/- 20% and 335% +/- 21% of basal values, respectively; however, the same concentrations of A23187 did not stimulate mucin secretion. Incubation of gallbladder explants in the presence of exogenous prostaglandin E2 or prostaglandin F2a in concentrations as high as 10(-6) mol/L also did not stimulate mucin secretion. Prairie dogs fed a lithogenic 1.2% cholesterol diet showed a significant increase in gallbladder mucin secretion after 1 week (117.5 +/- 10.2% of control, P less than 0.05), and 4 of 5 had formed cholesterol monohydrate crystals after 3 weeks. Long-term treatment with indomethacin, 1.2 mg.kg-1.day-1, failed to inhibit gallbladder mucin hypersecretion (129.2 +/- 10.7% of control after 1 week) or cholesterol monohydrate crystal formation (3/5) in cholesterol-fed prairie dogs. Furthermore, incubation of explants with 10(-5) mol/L indomethacin failed to prevent in vitro mucin hypersecretion in cholesterol-fed animals. These findings suggest that prostaglandins do not regulate gallbladder mucin secretion in the prairie dog, and it is unlikely that increases in gallbladder prostaglandin synthesis are responsible for mediating gallbladder mucin hypersecretion during cholelithiasis in the prairie dog.
Types of posterior capsular breaks and their surgical implications. We studied the pathogenesis, clinical features, and management of posterior capsular breaks in 28 cataract patients during planned extracapsular cataract extraction and intraocular lens implantation surgery. In the age-related cataract group (17 cases), the posterior capsular breaks were fresh, caused by the irrigation-aspiration cannula. Located in the upper part of the posterior capsule, they had thin margins and tended to enlarge with continued irrigation. Nine (52.9%) of these breaks could be plugged with viscoelastic, and after dry aspiration, a posterior chamber lens was implanted successfully. Posterior capsular breaks in traumatic cataracts (11 cases) were preexisting but were detected only during surgery. Centrally located, they had thick fibrosed margins and remained the same size during irrigation- aspiration. The minimal vitreous herniation seen in four (35.3%) of these cases was managed by automated partial anterior vitrectomy through the break. A posterior chamber intraocular lens was implanted in all these cases.
The protective role of eicosapentaenoic acid [EPA] in the pathogenesis of nephrolithiasis. The low incidence of atherosclerosis and other degenerative diseases including stone disease in the Greenland Eskimo has been attributed to their high consumption of oily fish with its high concentration of eicosapentaenoic acid (EPA). Man cannot synthesis EPA from the precursor essential fatty acid, linolenic acid, and can only assimilate preformed EPA present in fish and fish oil, to bring about a change in the pathway of eicosanoid metabolism from the n-6 to the n-3 series. With a westernised diet the oxygenated products of renal prostaglandin synthesis are metabolites of the n-6 series and these are known to play an important role in several pathophysiological states including stone disease. Our previous studies have shown a relationship between prostaglandin activity and urinary calcium excretion and it would seem that the initiating factor/s for stone formation trigger the mechanisms for prostaglandin synthesis resulting in the biochemical abnormalities associated with stone disease. The Eskimo may be protected from these events by possession of an eicosanoid metabolism that follows an n-3 pathway. To test this hypothesis experiments were performed using an animal model of nephrocalcinosis. The animals were divided into three groups; one group was given an intra-peritoneal injection of 10% calcium gluconate daily for 10 days to induce nephrocalcinosis; a second group was fed MaxEPA fish oil before and during the calcium gluconate injections and a third group only received an intra-peritoneal injection of N saline. A group of 12 recurrent, hypercalciuric/hyperoxaluric stone-formers were treated with fish oil for eight weeks to study the effects on solute excretion. Nephrocalcinosis, which was readily produced in the control animals, was prevented in the experimental animals by pre-treatment with fish oil and urine calcium excretion was significantly reduced. The urinary calcium and oxalate excretion in the recurrent, hypercalciuric stone-formers was significantly reduced with fish oil treatment over an eight week period. There were no untoward side-effects. These studies indicate that the incorporation of EPA in the diet as a substitute metabolic pathway could be a unique way of correcting the biochemical abnormalities of idiopathic urolithiasis.
Biased estimates of expected acute myocardial infarction mortality using MedisGroups admission severity groups This study examines whether the MedisGroups admission severity groups give unbiased estimates of 30-day mortality in 3037 Medicare-aged patients who were hospitalized in 1985 through 1986 with acute myocardial infarction. The average observed death rate for all acute myocardial infarction patients in the study who were in a given admission severity group was used to estimate the expected death probability for each case in a given group. (This is the same method used by the Pennsylvania Health Care Cost Containment Council for risk adjusting hospital mortality by diagnosis related groups in that state.) When compared with observed deaths, estimates of expected mortality were significantly biased for many patient attributes (eg, age, location of acute myocardial infarction, history of congestive heart failure, serum potassium level, serum urea nitrogen level, pulse rate, and blood pressure). These results are consistent with a conclusion that the MedisGroups scoring algorithm omits some important risk variables, inappropriately includes some other variables reflecting postadmission status, and gives the wrong weights to some appropriate risk variables. To the extent that these findings are also applicable to current MedisGroups scoring algorithms and to other conditions and procedures, MedisGroups admission severity groups cannot fairly adjust for interhospital case mix differences in outcome studies.
Cytoreduction and sequential resection: a hope for unresectable primary liver cancer. For decades, unresectable primary liver cancer (PLC) determined by operation was incurable. However, a retrospective study of 24 years' materials with unresectable PLC indicated that 5-year survival of unresectable PLC has increased from 0% in 1966-1977 (n = 137) to 16.9% in 1978-1989 (n = 345). This encouraging improvement was mainly a result of cytoreduction therapy followed by sequential resection. Multimodality combination treatment with hepatic artery ligation, plus hepatic artery infusion with chemotherapy, plus radioimmunotherapy (or radiotherapy) yielded the highest sequential resection rate (30.6%) and 5-year survival (28.0%) as compared with double combination and single modality treatment. The 5-year survival of 33 patients receiving sequential resection after cytoreduction therapy was 63.2%. It is suggested that cytoreduction and sequential resection might offer a hope for surgically verified unresectable PLC.
Visual acuity in infants after vitrectomy for severe retinopathy of prematurity [published erratum apppears in Ophthalmology 1991 Jul;98(7):1005] During the course of the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP), 98 infants (129 eyes) from the randomized segment of the trial developed total retinal detachment from retinopathy of prematurity (ROP) before the 1-year examination. The authors report as a case series the results of acuity card assessment of monocular grating acuity at 1 year in 53 infants (71 eyes) postvitrectomy and in 45 infants (58 eyes) who had retinal detachments but who did not undergo retinal reattachment surgery. The decision to undertake and the surgical technique used for a retinal reattachment procedure was not part of the randomized CRYO-ROP trial. Two eyes of one infant had pattern vision at the lowest measurable threshold after vitrectomy. None of the remaining eyes that had undergone vitrectomy and none of the eyes that did not undergo vitrectomy showed evidence of pattern vision. The relatively poor visual outcomes in this case series suggest that efforts are well-spent in attempting to prevent retinal detachment in ROP.
Human T-lymphotropic virus type 1-associated myelopathy and primary sclerosing cholangitis. We report the first case of human T-lymphotropic type 1-associated myelopathy (HAM) linked with primary sclerosing cholangitis (PSC). The patient, a 44-year-old woman, also suffered from ulcerative colitis and polyarthritis. Two years and nine months after the clinical onset of PSC, the coexistence of HAM was shown by neurological manifestations characterized by slowly progressive symmetrical myelopathy, predominantly involving pyramidal tracts, and positive antibodies to human T-lymphotropic virus type 1 in serum as well as in cerebrospinal fluid.
The effect of positive reinforcement on hourly compliance in nasal continuous positive airway pressure users with obstructive sleep apnea. Previous reports have described compliance with nasal continuous positive airway pressure (nCPAP) for the treatment of obstructive sleep apnea (OSA) only in terms of the number of patients able to use it beyond their initial trial night or those continuing after some home use. Because of a possible difference between the level of compliance (mean number of hours of use per 24 h) needed for symptomatic relief of OSA versus cardiovascular improvement, the level of hourly compliance in chronic nCPAP users may be important. The first part of this study prospectively examines compliance in a stable population of OSA patients already using nCPAP for 6 months to 2 yr. The second part is a prospective randomized, crossover study examining the effect of weekly (three times) then monthly (twice) positive reinforcement on hourly compliance of new nCPAP users for 3 months versus no reinforcement for 3 months. Positive reinforcement consisted of telephone discussions with the patients about the severity or complications of OSA, benefits of nCPAP, and suggestions about minimizing side effects. Using self-assessment scales, each patient reported the perceived level of improvement from the untreated to the treated condition and the prevalence and severity of side effects from the nCPAP therapy. The level of compliance in stable, chronic nCPAP users with OSA was 6.1 +/- 2.2 h/24 h (n = 9). For the new nCPAP users during the nonreinforced period, the mean compliance was 6.0 +/- 2.8 h/24 h; that during the reinforcement period was 6.0 +/- 2.7 h/24 h (NS). There was no significant correlation between perceived improvement in OSA symptoms or between the perceived side effects of nCPAP versus hourly compliance.
Prostatic abscess after transrectal ultrasound guided biopsy. We report a case of a diabetic man who had bilateral prostatic abscesses after ultrasound guided biopsy of the prostate. As is typical of prostatic abscesses, the diagnosis was not evident at presentation. We discuss the morbidity of transrectal biopsy and recommend consistent antimicrobial prophylaxis. We also recommend transrectal ultrasound in the diagnosis of such abscesses, and support the standard treatment of drainage and parenteral antimicrobial therapy. We anticipate that the incidence of prostatic abscess will increase due to the increasing number of men undergoing transrectal biopsy in the current age of transrectal ultrasound guided biopsy.
A lesson from the controversy about heart rate adjustment of ST segment depression. To summarize the literature review, the heart rate adjustment appears to be able to perfectly discriminate patients with different numbers of diseased coronary vessels in one center, to increase the diagnostic accuracy of three-vessel or left main disease in eight centers, and unable to improve accuracy in seven centers. To explain those differences, several methodological and statistical biases have been considered. However, a recent report regarding the application of the method in eight centers and a meticulous literature review could not explain the superior performance in some laboratories.
Diastolic mitral regurgitation with atrioventricular conduction abnormalities: relation of mitral flow velocity to transmitral pressure gradients in conscious dogs. Diastolic mitral regurgitation is a common finding that can be detected with use of Doppler echocardiographic techniques in patients with atrioventricular (AV) conduction abnormalities. With use of simultaneous hemodynamic and Doppler techniques, mitral flow velocity, mitral valve motion and transmitral pressure gradient were studied during 50 cardiac cycles each of spontaneous or atrial paced first- and second-degree AV block in five lightly sedated dogs. Diastolic mitral regurgitation was detected during atrial relaxation on all beats in which ventricular contraction was delayed greater than 190 ms. In all dogs the diastolic regurgitation was associated with a reverse transmitral pressure gradient (3.7 +/- 1.1 mm Hg in first-degree AV block and 3.2 +/- 1.5 mm Hg in second-degree AV block) that occurred primarily as the result of a decrease in atrial pressure with atrial relaxation. These reverse pressure gradients were as large as the maximal forward transmitral gradients in early diastole (2.9 +/- 0.9 mm Hg in first-degree AV block and 3.1 +/- 0.7 mm Hg in second-degree AV block) and larger than the maximal forward pressure gradients at atrial contraction (1.7 +/- 0.5 and 1.4 +/- 0.6 mm Hg, respectively, p less than 0.05). The maximal reverse pressure gradient during atrial relaxation was also as large as the reverse pressure gradient in mid-diastole (2.7 +/- 0.9 and 2.8 +/- 1.0 mm Hg, respectively), associated with deceleration of early diastolic mitral flow. Peak diastolic mitral regurgitation velocity coincided with the maximal reverse transmitral gradient and was usually larger than anterograde mitral flow velocity.
A prospective comparison of class IA, B, and C antiarrhythmic agents in combination with amiodarone in patients with inducible, sustained ventricular tachycardia BACKGROUND. Clinical experience suggests that combinations of antiarrhythmic agents provide more effective control of ventricular tachyarrhythmias than does therapy with single agents. METHODS AND RESULTS. Antiarrhythmic and electrophysiological effects of three class I antiarrhythmic agents, one from each subclass A, B, and C, were assessed in single use and in combination with amiodarone in patients with inducible, sustained ventricular tachycardia that was not suppressed by monotherapy with these agents. Thirty-one patients underwent an electrophysiology test on four occasions: at baseline; after 2-4 days of treatment with quinidine, mexiletine, or encainide; after 2 weeks of treatment with 1,200 mg/day amiodarone; and last, after 2-4 days of treatment with both amiodarone and the previously tested class I agent. The combination of a class I agent and amiodarone prevented the induction of sustained ventricular tachycardia in only one of 31 (3%) patients. Ventricular tachycardia became hemodynamically stable in 11 of 31 (34%) patients because of a marked prolongation in the tachycardia cycle length. It increased from 323 +/- 39 to 423 +/- 84 msec (n = 11, p less than 0.01) by adding encainide to amiodarone therapy, and it showed a tendency to lengthen when quinidine was added to amiodarone (from 373 +/- 77 to 425 +/- 58 msec; n = 10, NS). Each class I agent increased amiodarone-induced depression in myocardial conduction, but the extent of the additional depression seemed to differ among the three subclasses. Ventricular refractoriness was increased by all class I agents when used in combination with amiodarone, although not by mexiletine or encainide when used alone. CONCLUSIONS. Class I antiarrhythmic agents slow ventricular conduction and increase ventricular refractoriness when used in combination with amiodarone. When amiodarone and class I drugs by themselves do not suppress the induction of ventricular tachycardia, the combination of amiodarone and a class I agent seldom results in noninducibility; however, it often lengthens the ventricular tachycardia cycle length and may render the ventricular tachycardia hemodynamically stable.