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Biomedical subjects

M Saeed

Publications and source records attributed to M Saeed.

At least 181 records · Page 10Linked to original sources
PubMed1987

Stenoses in dialysis fistulas: treatment with percutaneous angioplasty.

Percutaneous transluminal angioplasty (PTA) was performed on 30 stenotic lesions in 25 dialysis access fistulas. The fistulas were in 23 patients with a mean age of 53 years. Lesions were detected with angiography within a few days after poor flow or increased venous pressure was documented during dialysis. Twenty-two lesions were in patients with polytetrafluoroethylene graft fistulas, five were in patients with bovine carotid fistulas, and three were in patients with endogenous arteriovenous fistulas. There were 28 venous stenoses (20 at the anastomotic site and eight more proximally) and two arterial stenoses. The overall success rate was 80%, with a 6-month patency of 76% and a mean patency after PTA of 9.4 months. Among the venous lesions, the success was 100% for proximal lesions and 71% for anastomotic lesions. There were two technical failures, which required surgery for revision of the fistulas, and four self-limited hematomas. PTA is a safe and effective treatment for stenoses in dialysis fistulas, particularly for lesions remote from the anastomotic sites.

Adult↗
PubMed1987

Pulmonary angiography with iopamidol: patient comfort, image quality, and hemodynamics.

The choice of a contrast agent for pulmonary angiography has important implications for patient comfort, image quality, and perhaps the safety of the procedure, particularly for "high-risk" patients. In a prospective study the nonionic, low-osmolality agent iopamidol eliminated the problem of image degradation due to coughing, and patients showed excellent tolerance for it. However, pressure measurements obtained within 3-5 minutes of injection of iopamidol and diatrizoate sodium meglumine 76% showed no significant difference in the hemodynamic effects of the two contrast agents, either for normotensive or for pulmonary hypertensive patients. Contrary to a common presumption, pulmonary hypertension by itself did not appear to increase the risk of pulmonary angiography. The theoretic presumption of greater hemodynamic stability with low-osmolality contrast agents was not clinically evident in this trial with iopamidol. At present, enhanced patient comfort and improved image quality remain the only confirmed bases for choosing this contrast agent for pulmonary angiography.

Adult↗
PubMed1987

Effect of nisoldipine on de-endothelialized large coronary artery in isolated working rabbit hearts.

The effect of nisoldipine on coronary vascular resistances, cardiac performance and myocardial oxygen consumption was determined. Rabbit hearts were perfused with a perfluorochemical (FC-43) emulsion. Endothelium was removed from the obtuse marginal and the upper portion of the anterior descending coronary artery. Changes in the internal diameter of these arteries were visualized using injection of Patent Blue Dye (color arteriography). Mean internal diameter of coronary arteries and surface area/unit length were computer calculated. Nisoldipine reduced the constriction of coronary arteries and the decrease on coronary flow induced by histamine. Nisoldipine abolished or reduced the decrease in cardiac output, LVESP, dP/dt and myocardial oxygen consumption. The results demonstrate that in the supported rabbit heart preparation, nisoldipine is an effective dilator of large subepicardial coronary arteries, deprived of endothelial lining, and counteracts constriction of coronary resistance vessels. As a consequence nisoldipine improves performance of the ischemic myocardium.

Animals↗
PubMed1987

Release of endothelium-derived relaxing factor from freshly harvested porcine endothelial cells.

Vascular relaxation in rabbit aortic preparations induced by acetylcholine is endothelium-dependent. The nature of the endothelium-derived relaxing factor (EDRF) has not been ascertained because it is very labile (reported half-life 6-50 seconds). To obtain a stable source of EDRF, a system was developed in which the relaxing factor was continuously produced by freshly harvested porcine endothelial cells. Endothelial cells were collected from aortas by exposing the endothelial lining to collagenase 0.1%. Cells were washed and concentrated by repeated centrifugation to obtain a high cell count (7.2 X 10(6) cells/ml). Endothelium-deprived aortic strips from rabbits were incubated in these cells suspended in tissue culture medium and fetal calf serum. The strips were precontracted with histamine. Acetylcholine was added to induce EDRF release. Significant relaxation of endothelium-deprived aortic strips was observed. Superoxide dismutase, an enzyme known to protect EDRF against inactivation, caused further relaxation, which was inhibited by the addition of hemoglobin, an agent known to inhibit the relaxing action of EDRF. Even without the addition of acetylcholine, hemoglobin caused contraction of the denuded aortic strips in suspension of porcine endothelial cells, demonstrating spontaneous EDRF release. Hemoglobin had no effect in cell-free medium. Endothelial-cell-dependent relaxation occurred without attachment of endothelial cells to the endothelium-deprived aortic strips: when the cell suspension was replaced by cell-free medium, relaxation did not occur after acetylcholine. Scanning electron microscopy showed no attachment of endothelial cells to the subendothelial layer. It can be concluded that freshly harvested endothelial cells produce endothelium-derived relaxing factor with an without stimulation by acetylcholine.

Acetylcholine↗
PubMed1987

Transthoracic needle aspiration: use of a small chest tube to treat pneumothorax.

The primary complication of transthoracic needle aspiration is pneumothorax. The efficacy and safety of using a small chest tube to treat this complication were examined by reviewing the records of 876 patients who underwent transthoracic needle aspirations between January 1981 and February 1986. Among these patients, 212 (24%) sustained a pneumothorax, and 92 (11%) required placement of a small 9-French chest tube attached to a flutter-type (Heimlich) valve. Duration of chest-tube drainage ranged between 24 hr and 3 weeks (mean, 2.2 days). Complete resolution of the pneumothorax and subsequent removal of the chest tube after 24 hr of drainage occurred in 38 (41%) of the 92 patients. Twenty-nine (32%) required 48 hr of drainage, and nine (10%) required 3 days. The remaining 16 (17%) required longer periods of drainage ranging from 4 days to 3 weeks. The tubes of six of this last group of patients were attached to a suction apparatus, and three of these patients eventually had a 28-French chest tube placed surgically. No significant complications occurred. The use of a small chest tube for treatment of pneumothorax after transthoracic needle aspiration is easy, safe, and efficacious.

Biopsy, Needle↗
PubMed1987

Paracardiac adenopathy: CT evaluation.

To establish the normal CT appearance of lymph nodes in the paracardiac area, we reviewed the CT scans of 50 patients without known malignancy or benign causes of lymphadenopathy. Five patients (10%) showed soft-tissue densities in the paracardiac region. The largest of these measured 3.5 mm. No more than two rounded soft-tissue densities were seen in any of the normal CT studies. Forty-five patients with paracardiac adenopathy were subsequently evaluated. In 27 (60%) of these the masses were due to either carcinoma, sarcoma, or benign disease. In 40%, the cause of paracardiac adenopathy was lymphoma. Features that favor a diagnosis of lymphoma are bilateral disease, multiple nodes, nodes greater than 2 cm in diameter, a lobulated or "matted" appearance, and associated pericardial thickening/effusion. Chest radiographs obtained within 2 weeks of the CT scans in 38 patients revealed only nine cases in which a paracardiac mass could be seen. This study suggests that 1 cm is the upper limit for the diameter of lymph nodes in the paracardiac region, and that paracardiac adenopathy may be caused by a wide variety of nonlymphomatous malignant and benign diseases in addition to lymphoma. Compared with CT, chest radiographs are insensitive for detecting paracardiac lymph node enlargement.

Colonic Neoplasms↗
PubMed1986

Effect of 8-bromo-cyclic guanosine monophosphate (cGMP) on coronary artery constriction in isolated rabbit hearts.

The vasodilator 8-bromo-guanosine 3':5'-monophosphate (8-bromo-cGMP) effectively counteracts vasopressin-induced coronary artery constriction in a supported perfused working rabbit heart. In this preparation, the coronary arteries remain in contact with the beating heart. The obtuse marginal artery and portions of the left anterior descending coronary artery were deprived of endothelium. Perfusion was carried out with Krebs-Henseleit solution, oxygenated with a disposable infant oxygenator. The internal diameter of large coronary arteries was determined by color arteriography (injection of patent blue dye and gated photography). The effect of vasopressin with and without the addition of 8-bromo-cGMP on cardiac performance (cardiac output, left ventricular systolic pressure, left ventricular end-diastolic pressure, maximal rate of rise in left ventricular pressure [dP/dtmax], mean aortic pressure) and large coronary vessel and total coronary vascular resistance was determined in nine experiments. In addition, changes in coronary sinus partial pressure of carbon dioxide (PCO2) and pH were observed. Vasopressin alone caused a significant decline in coronary flow, myocardial oxygen consumption and coronary sinus pH. Cardiac performance declined, probably because of myocardial ischemia. Large coronary vessel and total coronary vascular resistance rose. The vasodilator 8-bromo-cGMP strongly inhibited the vasoconstrictor action of vasopressin, counteracted the increase in large and total coronary vascular resistance, prevented the fall in myocardial oxygen consumption and eliminated changes in pH or PCO2 of coronary sinus effluent. Because of the elimination of myocardial ischemia by 8-bromo-cGMP, cardiac performance was normalized.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Infectious complications of percutaneous biliary drainage.

The infectious complications of percutaneous biliary drainage were reviewed in 132 patients with obstructive jaundice. Cholangitic or septic episodes occurred more frequently in patients with malignant (54%) than in those with benign (22%) disease, and frequently were not related to catheter insertions or manipulations. The frequency and mechanisms of bacterial colonization of bile and blood in patients with obstructive jaundice before and after biliary drainage are reviewed. The significant morbidity and mortality related to postdrainage infectious episodes is stressed, and the efficacy of antibiotic prophylaxis is discussed. The significant risks and complications of percutaneous biliary drainage must be considered prior to catheter placement, particularly in the most debilitated patients.

Bacterial Infections↗
PubMed1985

Effect of intact endothelium against platelet-induced coronary artery spasm in isolated rabbit hearts.

Effects of collagen-activated washed rabbit platelets on coronary arteries with and without intact endothelium were studied in a supported rabbit heart preparation using a perfluorocarbon (FC-43) as perfusate. The vascular diameter of obtuse marginal coronary arteries was determined by means of gated color arteriography (injection of patent blue dye). Endothelial denudation of the obtuse marginal artery was accomplished by scraping the lumen with a roughened plastic tubing. Injection of washed platelets (10 ml with about 500,000 platelets/microliters) not treated with collagen failed to constrict coronary arteries either with intact or denuded endothelium. In contrast, injection of platelet suspension immediately after activation with collagen caused vasoconstriction of denuded obtuse marginal coronary arteries in 10 of 14 cases. In 6 preparations occlusion was complete, lasting up to 16 minutes. In arteries with intact endothelium, no coronary vasoconstriction occurred. In hearts with coronary artery spasm, total coronary vascular resistance increased significantly. This study furnishes additional evidence that endothelial lesions are a contributory factor for large coronary artery spasm and that endothelial cells possess a protective function against vasoconstrictor substances released from aggregating platelets.

Animals↗
PubMed1983

Attenuation of sympathetic vasoconstriction by nifedipine: the role of vascular alpha 2-adrenoceptors.

The effects of nifedipine on hindlimb vasoconstriction caused by norepinephrine infusion and sympathetic stimulation (0.1-1.0 Hz) were compared in dogs given 0.12 mg/kg prazosin or 0.3 mg/kg rauwolscine. Constrictions due to stimulation or norephinephrine with prazosin, presumed to be mediated by vascular alpha 2-adrenoceptors, were significantly attenuated by 30 micrograms/kg nifedipine, while constrictions with rauwolscine, presumably alpha 1-mediated, remained unaffected. These data support the hypothesis that the antihypertensive effect of calcium antagonists is based upon interference with alpha 2-mediated sympathetic vasoconstriction.

Animals↗
PubMed1982

Norepinephrine constricts the canine coronary bed via postsynaptic alpha 2-adrenoceptors.

The effect of alpha 2-blockade (0.3 mg/kg i.v. rauwolscine) and alpha 1-blockade (1.2 mg/kg i.v. prazosin) on coronary constrictions induced by intracoronary injections of azepexole (B-HT 933, alpha 2-agonist, 0.1-10 microgram/kg), phenylephrine (0.3-3 microgram/kg) and norepinephrine (0.001-0.1 microgram/kg) were studied in dog hearts perfused in situ under beta-blockade. Constrictions by azepexole (antagonized by rauwolscine, yet resistant to prazosin and methysergide) demonstrated coronary alpha 2-adrenoceptors. Norepinephrine-induced constrictions were more attenuated (22-fold) by alpha 2-blockade than by alpha 1-blockade (2.6-fold) and thus were mediated mainly by activation of postsynaptic alpha 2-receptors.

Animals↗
PubMed1979

Herpesvirus hominis (type 1) proctitis.

Herpes proctitis from Herpesvirus hominis type 1 is probably an underrecognized cause of rectal pain and inflammation. Extreme anal pain and a purulent rectal discharge in a heterosexual man led to the appropriate diagnosis. Clinicians should be more aware of herpes as a cause of proctitis.

Herpes Simplex↗
PubMedDate not supplied

Dual effects of gadodiamide injection in depiction of the region of myocardial ischemia.

The high safety index of the nonionic magnetic resonance (MR) contrast agent gadodiamide injection permits a wide dose range without induction of hemodynamic effects. The wide dose range might confer a diagnostic advantage by providing both T1 enhancing and magnetic susceptibility effects for demarcating pathologic regions. The dual utility of this contrast agent for T1 and T2 enhancement in creating differential contrast between normal and acutely ischemic myocardium was explored. MR imaging was initiated 20-40 minutes after occlusion of the left coronary artery in two groups of rats: Group 1 (n = 8) received 0.3 mmol/kg gadodiamide injection before and after acquisition of T1-weighted images; group 2 (n = 10) received 0.5 mmol/kg before and after acquisition of T2-weighted images. Postcontrast T1-weighted images showed clear delineation of the ischemic region as a relatively low-signal-intensity area for 15 minutes. On postcontrast T2-weighted images, the ischemic region appeared as a relatively high-signal-intensity area for 60 minutes. These effects were obtained with doses of gadodiamide injection that have safety indexes greater than those of gadopentetate dimeglumine.

Animals↗