123rc/medical_text huggingface dataset:
Mechanisms for left ventricular systolic dysfunction in aortic regurgitation: importance for predicting the functional response to aortic valve replacement To test the hypothesis that the combined use of the time-varying elastance concept and conventional circumferential stress-shortening relations would elucidate differential mechanisms for left ventricular systolic dysfunction in severe, chronic aortic regurgitation and therefore predict the functional responses to aortic valve replacement, 31 control patients and 37 patients with aortic regurgitation were studied. The studies included micromanometer left ventricular pressure determinations, biplane contrast cineangiograms under control conditions and radionuclide angiograms under control conditions and during methoxamine or nitroprusside infusions with right atrial pacing. The patients with aortic regurgitation were classified into three groups: Group I had normal Emax and stress-shortening relations, Group II had abnormal Emax but normal stress-shortening relations and Group III had abnormal Emax and stress-shortening relations. The left ventricular end-diastolic and end-systolic volumes showed a progressive increase and the ejection fraction showed a progressive decrease from Group I to III; these values differed from those in the control patients (p less than 0.001). In Group I, there was a decrease in left ventricular volumes (p less than 0.05) but no significant change in ejection fraction (61 +/- 7% versus 63 +/- 4%) after aortic valve replacement. In contrast, in Group II, reduction in left ventricular volumes (p less than 0.01) was associated with an increase in ejection fraction from 50 +/- 8% to 64 +/- 11% (p less than 0.01). Finally, in Group III, reduction in left ventricular volumes (p less than 0.05) was associated with a further decrement in ejection fraction from 35 +/- 13% to 30 +/- 13%. Group I patients had compensated adequately for chronic volume overload. However, Group II had left ventricular dysfunction that was associated with an increase in the left ventricular volume/mass ratio compared with that in the control patients and Group I (p less than 0.05 for both), suggesting inadequate hypertrophy and assumption of spherical geometry. Finally, irreversible myocardial dysfunction had supervened in Group III. In conclusion, a combined analysis of left ventricular chamber performance using the time-varying elastance concept and myocardial performance using conventional circumferential stress-shortening relations provides complementary information that elucidates differential mechanisms for left ventricular systolic dysfunction and therefore predicts the functional response to aortic valve replacement.
Echocardiographic measurement of left ventricular mass and volume in normotensive and hypertensive rats. Necropsy validation. Although rats are commonly used to study left ventricular (LV) hypertrophy, measurement of LV mass and dimensions has required killing the rat. To determine the accuracy of echocardiography in rats, blinded crossectional area (CSA) and LV mass measurements using either the cube function (LVM) or an elliptical model (LVMel) from high resolution M-mode echocardiograms were compared to necropsy LV weight (0.28 to 1.5 g), in 41 normotensive (body weight 116 to 762 g) and 17 hypertensive rats (350 to 560 g). Postmortem chamber volumes in 28 normal rats (0.02 to 0.19 mL) were also compared to echocardiographic volumes derived from the elliptical model. Correlation with LV weight was r = 0.87 for LVM, 0.90 for CSA and 0.93 for LVMel (all P less than .00001). Comparison of hypertensive and body-weight-matched normotensive rats revealed the upper normal limit for both LVMel and CSA to have 89% sensitivity and 100% specificity for detection of post mortem LV hypertrophy. Necropsy LV volumes were more closely related to systolic echocardiographic volumes than to diastolic volumes (r = 0.78 v 0.71, both P less than .00001), compatible with the effects of post mortem contracture. Stroke volume determined invasively in 5 Wistar rats by thermodilution was similar to that obtained using elliptical model echo volumes in 5 rats of the same body size (0.35 +/- 0.05 v 0.30 +/- 0.06 mL/beat). Echocardiography can be used to evaluate LV structure and function in rats and to detect in vivo LV anatomic differences induced by hypertension.
Axial rotation of the lumbar spine and the effect of flexion. An in vitro and in vivo biomechanical study. A series of experiments were performed on eight whole, cadaveric lumbar spines and on eight male volunteers to determine whether axial rotation changed with subjects bending forward compared with being in a neutral posture and whether rotation was affected by articular tropism. Kirschner wires were inserted into the spinous processes of the eight cadaveric lumbar spines, and the axial rotation of the wires was measured while the spine was rotated in a torsion apparatus. Similarly, Steinmann pins were inserted into the spinous processes of L3, L4, and L5 of the eight volunteers, and the axial rotation of the pins was measured while the subjects rotated in a torsion apparatus. Axial rotation was found to be less when combined with forward flexion, and articular tropism did not influence the amplitude of rotation.
Loss of expression of blood group antigen H is associated with cellular invasion and spread of oral squamous cell carcinomas. Membrane-bound carbohydrates may influence the metastatic behavior of cancer cells. Forty-two squamous cell carcinomas (SCC) of the buccal and maxillary alveolar mucosa were studied retrospectively using a monoclonal antibody (BE2) that reacts with blood group H (type 2 chain) structure and an immunoperoxidase (avidin-biotin peroxidase complex) staining technique. H-antigen staining within the entire tumor did not correlate with the stage of the tumor, i.e., tumor spread. However, loss of staining within the most invasive sites of the tumors correlated significantly with the stage of tumor development and histologic grade of malignancy. These findings support the view that features regarding the cells of deeper parts of the carcinomas are very important for the clinical behavior of the tumors and that loss of H-antigen expression is related to the stage of the tumor and invasion of carcinoma cells.
The contribution of median nerve SEPs in the functional assessment of the cervical spinal cord in syringomyelia. A study of 24 patients. Since the early study of Halliday and Wakefield (1963) it has generally been agreed that scalp somatosensory evoked potentials (SEPs) are normal in patients with dissociated loss of pain and temperature sensation. Up to now a few patients with abnormal spinal N13 and preserved scalp P14 and N20 have been reported in the literature, but there is no firm evidence, based on group data, that this dissociation can be related to any form of dissociated sensory loss. We studied median nerve SEPs in 24 patients with syringomyelia documented by CT scan or MRI. For the recording of the cervical N13 we used a Cv6 anterior cervical montage, which cancels the potentials generated above the foramen magnum and enhances the amplitude of N13. Scalp far-field and early cortical SEPs were recorded using a noncephalic reference electrode. Since N13 pathological changes are mainly changes in amplitude we measured the N13/P9 amplitude ratio in normal subjects and patients and found that it was a reliable index to quantify the amplitude decrease of N13. Absent or reduced N13 was observed in 40 median nerve SEPs (83%) in conjunction with normal P14 and N20 in 30 SEPs. Thus the dissociated loss of the cervical N13 was identified as the most conspicuous SEP feature in syringomyelia. A significant correlation was found between abnormal N13 and loss of pain and temperature sensations, whereas P14 abnormalities correlated well only with loss of joint and touch sensations. In the median nerve territory, sensation was either normal (6 cases) or lost only for pain and temperature (24 cases) when SEPs showed abnormal N13 and normal P14. Although it does not directly reflect the postsynaptic activity of spinal cells receiving their inputs from A delta and C fibres the N13 potential proved to be a reliable index of spinal cord grey matter dysfunction in syringomyelia.
Synergism of ara-C-imuvert combination in aborting the development of transplanted chloroleukemia in the rat. The development of chloroleukemia in the rat after transplantation of C51 chloroma cells can be aborted by treatment with an exogenous source of differentiating activity (DA) or by stimulation of endogenous DA production by the administration of Imuvert, a biologic response modifier. Success or failure of treatment was determined by the ratio of DA to leukemic cell load. Accordingly, in the present study we examined the hypothesis that treatment with cytosine arabinoside (ARA-C) to reduce the leukemic cell load coupled with Imuvert would be more effective than either given alone. Treatment with ARA-C-Imuvert aborted the development of chloroleukemia in 79% of the animals in contrast to 0%, 9% and 45% in animals treated with buffer, ARA-C, or Imuvert respectively. These results suggest that stimulation of endogenous DA in combination with cytoreductive agents offers a potentially curative treatment for myelogenous leukemia.
Intraocular pressure increases with fenoldopam, but not nitroprusside, in hypertensive humans. Fenoldopam mesylate stimulates adenyl cyclase in porcine ocular trabecular meshwork and raises intraocular pressure in humans. To clarify whether this results from direct activation of the dopamine-1 receptor or indirectly from baroreflex sympathetic stimulation after blood pressure reduction, intraocular pressure was measured in 14 patients with accelerated/malignant hypertension, randomized between intravenous fenoldopam or sodium nitroprusside. Intraocular pressure was measured with a Perkins tonometer, before and at the twentieth minute of each dose increment. In seven patients with a mean blood pressure of 232/131 mm Hg treated with fenoldopam, intraocular pressure increased in a dose-dependent fashion, from 16 +/- 1 to 20 +/- 2 mm Hg (p less than 0.005). In contrast, seven patients with a mean blood pressure of 225/134 mm Hg treated with sodium nitroprusside exhibited no change in intraocular pressure (15 +/- 1 versus 14 +/- 1 mm Hg) despite similar blood pressure reduction. Increases in heart rate were not significantly different. Rates of urinary excretion of norepinephrine plus epinephrine increased significantly relative to baseline (p less than 0.05) but were not different between groups. These data suggest that the increase in intraocular pressure with fenoldopam results from specific activation of the dopamine-1 receptor and is not caused by baroreflex sympathetic stimulation. Because dopamine-1 receptors may modulate intraocular pressure, dopamine-1 receptor blockers might be useful therapy for glaucoma.
Primary varicose veins: topographic and hemodynamic correlations. This study was conducted to correlate the clinical presentations of uncomplicated primary varicose veins with the topographic and anatomic source of reflux (escape points). One-hundred sixty-three patients with primary varicose veins (144 females, 19 males; 96 unilateral, 67 bilateral) in 230 involved limbs were examined. The origin and extent of venous reflux was traced with Doppler ultrasound. Three distinct groups were recognized. Group I. Typical saphenous varicosities with junctional escapes occurred in 164 (71.3%). Sapheno-femoral junction (SFJ) incompetence in 147, and sapheno-popliteal junction (SPJ) incompetence in 17 limbs. Group II. Atypical saphenous varicosities with non-junctional escapes occurred in 51 (22.17%) limbs. In 5 limbs, no escape was detected. Twenty-two limbs had escapes localized in the main perforators: mid-thigh perforator 17, upper calf 2, distal ankle in 3. Twenty-four limbs had their escapes in the auxiliary perforators: abdomino-pelvic 17, and circumflex iliac/external epigastric, 7 limbs. Group III. Non saphenous (lateral venous system) varicosities occurred in 15 (6.52%) limbs. Based on physical examination alone, 55 limbs would possibly have undergone unnecessary ankle to groin stripping and 83 limbs an unnecessary SFJ ligation. Doppler US is an essential diagnostic tool that can accurately map the origin and extent of the venous reflux. The obtained hemodynamic information will permit more selective, multimodal therapy and avoid the indiscriminate, often unnecessary stripping of the entire saphenous system in all cases of primary varicose veins.
Dissection of the aorta and dissecting aortic aneurysms. Improving early and long-term surgical results. We report the improving surgical results in a consecutive series of 690 patients referred to one of us (E.S.C.) for aortic dissection between December 1956 and September 1989, a substantial portion of whom had dissection as a complication of either previous aortic (n = 113, 16) or previous cardiac (n = 54, 8%) operation. Our initial operation of choice in patients requiring multiple operations in this group of 690 patients was based on the most life-threatening or symptomatic aortic segment involved, which was ascending aorta and/or aortic arch (Asc/Arch) in 301 (44%) patients, descending thoracic aorta (Desc) in 195 (28%) patients, and thoracoabdominal aorta (TaA) in 194 (28%) patients. As detailed below, considerable improvement occurred in the 30-day survival rates over time, particularly for acute dissection: [table; see text] The independent determinants of both early and long-term mortality were identified. Independent determinants of late fatal rupture, reoperation, and neuromuscular dysfunction for distal dissectors were also identified. In our experience, continued aggressive surgical intervention for aortic dissection with modern operative techniques has resulted in markedly improved 30-day operative survival (approaching 95% including those patients with acute dissection) and significant improvement in late results.
Fibrillation potential amplitude and muscle atrophy following peripheral nerve injury. Maximum peak-to-peak fibrillation potential amplitude was measured in 69 subjects between 7 days and 10 1/2 years post complete or partial peripheral nerve injury. Mean amplitude during the first 2 months was 612 muV; third and fourth months 512 muV, fifth and sixth months 320 muV. After the first year, no population of fibrillation potentials greater than 100 muV was recorded. The sciatic nerve was sectioned in 13 guinea pigs and animals studied up to 17 weeks. Fibrillation potential amplitude in gastrocnemius muscles declined paralleling that in humans. By the end of the study, type I fibers had lost almost half of their initial diameter and type II fibers had atrophied more than twice this amount. Fibrillation potential amplitude may be useful in estimating the time post nerve injury and appears to correlate with the surface area and fiber diameter of a type I muscle fiber.
Comparison of vastus medialis obliquus: vastus lateralis muscle integrated electromyographic ratios between healthy subjects and patients with patellofemoral pain. The purpose of this study was to compare vastus medialis obliquus:vastus lateralis muscle (VMO:VL) integrated electromyographic (IEMG) ratios of healthy subjects and patients with unilateral patellofemoral pain (PFP) under isotonic and isometric quadriceps femoris muscle contraction conditions. Subjects ranging in age from 18 to 35 years (mean = 28.06, SD = 5.97) were assigned to one of three groups on the basis of type of knee condition. In group 1, which consisted of seven healthy control subjects with no history of knee pathology, both knees were tested. In group 2, which consisted of nine patients with unilateral PFP, only the painful knee was tested. In group 3, which consisted of the same nine patients who comprised group 2, only the nonpainful knee was tested. Nonnormalized and normalized VMO:VL IEMG ratios were computed for ascending stairs, descending stairs, submaximal isometric contraction, and maximal isometric contraction (nonnormalized only). A two-way analysis of variance for repeated measures indicated VMO:VL ratios for isotonic stair-climbing activities were significantly greater than VMO:VL ratios for isometric contractions. Nonnormalized VMO:VL ratios in group 1 were significantly greater than nonnormalized VMO:VL ratios in the other two groups. Patients with PFP may have abnormal VMO:VL activation patterns, and isotonic quadriceps femoris muscle exercise may elicit more favorable muscle activation patterns than isometric exercise for patients with PFP.
Meropenem pharmacokinetics and penetration into an inflammatory exudate. The pharmacokinetics and penetration into a cantharidine-induced inflammatory exudate of meropenem was studied in six volunteers following a single 1-g intravenous dose. Concentrations in plasma, urine, and the inflammatory exudate were determined by a microbiological assay. The mean elimination half-life of meropenem in plasma was 1.1 h, with the concentration in plasma declining from a mean of 23.6 micrograms/ml at 1 h to 0.7 micrograms/ml at 6 h. The inflammatory fluid penetration was rapid (time to maximum concentration of drug in serum, 0.75 h), and the penetration was 111%. The recovery of meropenem in urine at 24 h was 65.4% of the administered dose.
Effects of ischemia and hemoglobin on vascular function in isolated rabbit aortas. The vascular endothelium is important in the modulation of vascular tone via production of endothelium-derived relaxing and contracting factors. The abdominal aortas of five groups of rabbits were subjected to varying lengths of ischemia (0, 1, 2, 3, or 4 hours), removed, sectioned into transverse rings, and placed in tissue baths containing Krebs' buffer at 37 degrees C and aerated with 95% O2/5% CO2. After equilibration the rings were tested for endothelium-dependent vasodilation with methacholine and nonendothelium-dependent vasodilation with nitroprusside. Endothelium-dependent relaxation as elicited by methacholine was impaired at 3 and 4 hours of ischemia but was not significantly different at 1 and 2 hours as compared to control, whereas endothelium-independent vasodilation remained normal throughout the different periods of ischemia. The addition of 1 x 10(-6) mol/L rabbit hemoglobin reduced the time needed to demonstrate significant impairment of endothelial function to 2 hours. Endothelium-independent vasodilation was not affected by hemoglobin. We conclude that hemoglobin exacerbates ischemia vascular dysfunction in the rabbit aorta.
Extracorporeal shock wave lithotripsy for biliary stones. Extracorporeal shock wave lithotripsy is a noninvasive technique for treatment of patients with gallbladder and bile duct stones. Selected patients with gallbladder stones can be treated on an outpatient basis without general anesthesia and may return to full activity within 1 or 2 days. Stone-free rates of 40% to 60% at 6 months have been achieved in most reported series with minimal morbidity. Bile duct stone lithotripsy has achieved stone clearance in 80% of patients in whom conventional methods were unsuccessful and therefore constitutes a valuable second-line treatment for these patients.
Papillary adenocarcinoma of the middle ear. A case of papillary adenocarcinoma of the middle ear is presented. The patient had an unusually short history of otalgia, aural discharge and facial palsy, and, at presentation the tumour was too large for surgical resection to be a feasible option. The management of this rare tumour is discussed and the relevant literature reviewed.
Cardiac arrest due to spontaneous coronary artery dissection in a patient with coronary ectasia--a case report. Spontaneous coronary artery dissection is a rare event and only in a few patients has the diagnosis been angiographically confirmed during life. A spontaneous dissection of the right coronary artery was detected as a cause of out-of-hospital cardiac arrest in a patient with coronary artery ectasia.
Frequency of low-grade residual coronary stenosis after thrombolysis during acute myocardial infarction. The clinical, angiographic and demographic characteristics of 42 patients with low-grade (less than 50%) residual stenosis at the infarct lesion after thrombolysis for acute myocardial infarction (MI) were assessed. The study group (group I) represented 21% of 198 consecutive patients receiving thrombolytic therapy over a 59-month period. Data on the 156 remaining patients were pooled for comparison (group II). Group I patients were predominantly men (86%) who were cigarette smokers (81%). Group II patients were predominantly men (75%, p greater than 0.10) but were significantly older (52 +/- 12 vs 56 +/- 10 years, p = 0.02). Prior acute MI or angina was unusual in group I. Sixty percent had no significant (greater than 50%) residual coronary artery disease while 25% had residual single artery disease. Average significant (greater than 50% diameter stenosis) residual vessel disease was 0.6 +/- 1.0 for group I and 1.9 +/- 0.9 for group II (p less than 0.001). In group I, average residual infarct lesion diameter stenosis was 36 +/- 7% in the right anterior oblique and 34 +/- 8% in the left anterior oblique views. Thirty-nine group I patients were discharged with medical therapy and 100% follow-up was obtained over a mean interval of 18 +/- 17 months. Fifteen patients experienced chest pain after acute MI accounting for 17 discrete events. Fifty-nine percent of group I had a benign course on follow-up. Eight events were classified as unstable angina, 4 as acute MI and 5 as atypical angina. Documented coronary vasospasm occurred in 3.
Avoiding interpretive pitfalls when assessing arrhythmia suppression after myocardial infarction: insights from the long-term observations of the placebo-treated patients in the Cardiac Arrhythmia Pilot Study (CAPS) The Cardiac Arrhythmia Pilot Study (CAPS) was a 1 year trial that analyzed the safety and effectiveness of arrhythmia suppression in 502 patients surviving acute myocardial infarction who had greater than or equal to 10 ventricular premature depolarizations/h or greater than or equal to 5 runs of ventricular tachycardia on a Holter recording obtained 6 to 60 days after the acute infarction. Because 100 of these patients received placebo in a double-blind fashion for 1 year, a comprehensive objective analysis was performed of spontaneous arrhythmia changes based on real data rather than statistical estimates. In the CAPS placebo group, 19% developed some serious clinical event in 1 year (death, heart failure, proarrhythmia) that could likely be attributable to antiarrhythmic drug toxicity. A significant reduction in the frequency of ventricular premature depolarizations (p = 0.004) occurred in the first few weeks of "therapy" with a further significant (p less than 0.04) decrease between 3 to 12 months. After initiation of placebo antiarrhythmic therapy, 27% had "apparent ventricular premature depolarization suppression" (greater than or equal to 70% reduction) after one Holter recording evaluation and nearly half (48%) after six Holter recordings to assess suppression were performed.