PubMed Health⌕ Search

Biomedical subjects

M D Cohen

Publications and source records attributed to M D Cohen.

At least 127 records · Page 7Linked to original sources
PubMed1989

Effects of regional alpha- and beta-blockade on resting and hyperemic coronary blood flow in conscious, unstressed humans.

Our purpose was to determine if there are basal adrenergic influences on the coronary circulation in humans. We studied 56 patients with denervated hearts after cardiac transplantation and 19 normally innervated patients with angiographically normal coronary arteries. Coronary blood flow velocity was measured during cardiac catheterization with a subselective 3F intracoronary Doppler catheter. Heart rate was controlled by atrial pacing. Epicardial coronary artery diameter was measured by automated analysis of digital coronary angiograms. Coronary flow reserve was assessed by intracoronary papaverine hydrochloride (12 mg) injections. Regional sympathetic blockade was produced by intracoronary injections of phentolamine (3 mg, alpha) and propranolol (2 mg, beta) or metoprolol (3 mg, beta 1). After alpha-blockade, mean arterial pressure fell significantly (p less than 0.05) in both the denervated transplant (-5.8 +/- 1.5%) (mean +/- SEM) and normally innervated patients (-12.6 +/- 3.2%). Reductions in coronary flow velocity also were observed in these groups (-8.2 +/- 2.3% and -9.2 +/- 5.8%, respectively). Calculated coronary vascular resistance was unchanged. Similar changes were seen when patients were pretreated with beta-blockade before alpha-blockade. Nonspecific beta-blockade did not affect mean arterial pressure but decreased coronary velocity (innervated, -11.6 +/- 3.9%; denervated, -9.3 +/- 2.4%) and increased coronary vascular resistance (innervated, 15.4 +/- 6.7%; denervated, 10.2 +/- 3.7%). Coronary vascular resistance did not rise in either group after selective beta 1-blockade with metoprolol. Coronary flow reserve did not change in either patient group after either alpha- or beta-blockade. Changes in epicardial coronary artery diameter were small and generally not significant. These data suggest that alpha-receptor-mediated vascular tone is negligible in both denervated transplant patients and normally innervated patients. Additionally, the increase in vascular resistance after nonselective beta-blockade is the result of direct beta 2 vascular effects. Our data further suggest that there is little adrenergically mediated epicardial artery tone (either humoral or neural) at rest and that maximal vasodilator responses are not limited by adrenergically mediated vasomotor tone.

Adrenergic alpha-Antagonists↗
PubMed1989

Laser cameras and radiology department design.

Although newer imaging modalities provide many options for the acquisition, processing, storage, and display of images, film is still an important means of storing and displaying images. Laser cameras may be used to record images from a variety of imaging instruments on film, offering several advantages over conventional multiformat cameras. When a laser camera purchase is planned, several installation requirements must be kept in mind. These are illustrated by showing how laser cameras have been incorporated into a new radiology department.

Hospital Departments↗
PubMed1989

Congenital candida pneumonia and sepsis: a case report and review of the literature.

A term newborn with Candida albicans infection of the lungs and blood is described. Although no maternal risk factors were identified, this patient's rapid clinical deterioration and postmortem findings suggest congenital infection. Related cases in the literature are reviewed. This case suggests that a diagnosis of fungal pneumonia should be considered in any infant presenting with severe respiratory distress.

Adult↗
PubMed1988

Effects of ammonium metavanadate treatment upon macrophage glutathione redox cycle activity, superoxide production, and intracellular glutathione status.

Female B6C3F1 mice were given intraperitoneal injections of ammonium metavanadate (2.5 or 10 mg V/Kg), ammonium chloride, or sodium phosphate buffer every 3 days for 6 weeks. Resident peritoneal macrophages were harvested, lysed by freeze-thawing, and the resulting cytolysate was assayed for total protein content and enzyme activities of glutathione reductase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase. In addition, peritoneal macrophages were assayed for superoxide production using nitroblue tetrazolium reduction, as well as for intracellular levels of oxidized and reduced glutathione. Exposure of mice to vanadium resulted in a dose-trend depression in the three macrophage enzyme activities as compared with the controls. Vanadium treatment resulted in a similar decrease in the production of superoxide anion, and an increase in levels of oxidized glutathione; however, the total glutathione pool (reduced plus oxidized forms) was not affected.

Animals↗
PubMed1988

Percutaneous nonendoscopic gastrostomy in children.

Surgical gastrostomy has long been a standard method of providing nutrition to infants and children. Recently, percutaneous endoscopic gastrostomy has been advocated as a safer, quicker, less expensive method in children. We report our experience with 16 percutaneous gastrostomies in 14 infants and children; in all cases, both sonographic and fluoroscopic guidance were used. Four patients had had previous surgical gastrostomy in which the tubes could not be replaced once they were removed. The remaining patients were referred for percutaneous placement of gastrostomy tubes as the first procedure. In 13 procedures, parenteral sedation and local anesthesia were used; the remaining three procedures were done with the patient under general anesthesia. Tubes were successfully placed in all procedures. In two patients, tubes became dislodged, necessitating a second procedure. There were no instances of local infections, hemorrhage, or peritonitis, and none of the patients died. Two patients had postprocedure septicemia, which responded to antibiotics. Percutaneous nonendoscopic gastrostomy can be safely and effectively performed in infants and children.

Adolescent↗
PubMed1987

Uptake of technetium 99m MDP by hepatoblastoma.

Focal uptake of 99mTc-MDP was seen in a case of hepatoblastoma. The focal uptake corresponded to an area of calcification on CT, which was shown histologically to consist of osteoid with mineralization. The mechanism of uptake by the tumor in this case is likely to be the same as for skeletal uptake.

Calcinosis↗
PubMed1987

A preliminary study of age-related difference in resistance to sepsis in the rat model.

Although the pathophysiology of intraabdominal sepsis is well established in the adult animal, there is a paucity of similar information in the newborn animal. Using the Wichterman (K.A. Wichterman, A.E. Baue, and I.H. Chaudry, Journal of Surgical Research 29: 189, 1980) model of intraabdominal sepsis, 42 Sprague-Dawley suckling rat pups and 42 adults underwent cecal ligation followed by a single needle puncture of the cecum. Whereas a mortality of 47.6% was noted in the adult animals, only 7.1% of the suckling animals succumbed by the end of 1 week. After the ip LD50 of Escherichia coli was determined independently in each age group, appropriate doses of the bacteria were injected into the peritoneums of 36 suckling and 30 adult rats. The peritoneal fluid was aspirated at 0, 2, 4, 8, 24, and 48 hr and the bacterial concentration in the suspension was determined. The rate of bacterial clearance from the peritoneum of the suckling rats was found to be significantly greater at 2, 4, and 8 hr as compared with the adult animal. In vitro assay of the phagocytic activity of the peritoneal macrophages demonstrated a significantly higher activity in the cells obtained from the suckling rats than in those from the adult (P less than 0.05). A more efficient bacterial clearance and a higher phagocytic activity in the peritoneal macrophages of the suckling rats may contribute to the difference in the mortality between the two age groups.

Aging↗
PubMed1987

Neonatal tracheobronchomegaly.

Tracheobronchomegaly is rarely reported in neonates. We present five cases of tracheobronchomegaly occurring in neonates receiving intensive ventilatory and oxygen support. Barotrauma is speculated to be the primary pathophysiologic factor in these cases.

Diseases in Twins↗
PubMed1987

Thymus in the superior mediastinum simulating adenopathy: appearance on CT.

A soft-tissue nodule was identified in the mediastinum superior to the left brachiocephalic vein in six patients undergoing computed tomography (CT) of the chest. In one case, biopsy of the mass showed that it was thymic tissue. In the remaining cases, the nodule was identified as thymus on the basis of the CT findings. The findings include equal density of the superior mediastinal nodule and the thymic lobes anterior to the ascending aorta, no displacement or narrowing of adjacent arteries, absence of a fat plane between the nodule and the thymic lobes, and parallel reduction in size of the nodule and the rest of the thymus. Two patients were examined with magnetic resonance (MR) imaging. Sagittal MR images demonstrated continuity of the superior mediastinal nodule with the more caudal portion of the thymus. Recognition of this normal variant in children is important in order to avoid unnecessary mediastinal biopsies or overstaging of malignancies.

Adolescent↗
PubMed1987

Evaluation of pulmonary parenchymal disease by magnetic resonance imaging.

Thirty-eight patients with a wide variety of different disorders of the lung have been imaged using magnetic resonance. The disorders studied include congenital abnormalities, acute and chronic inflammation, vascular disorders, primary and secondary tumours of the lung, haematomas and infarcts. Magnetic resonance imaging identified all lesions seen on chest radiographs, but it is not quite as sensitive as computed tomography is for detection of very small abnormalities. Magnetic resonance may provide information to aid in differentiation of a wide variety of disorders causing diffuse pulmonary abnormality and might also prove helpful in differentiating acute inflammation from pulmonary collapse or fibrosis. In some disorders, such as lobar emphysema, cystic adenomatoid malformation and sequestration, the findings on the magnetic resonance scan alone will permit a correct diagnosis to be made in many cases. It is believed that magnetic resonance imaging has more potential for pulmonary imaging than has previously been recognised.

Adolescent↗
PubMed1987

MR imaging of osteogenic and Ewing's sarcoma.

Twenty patients with biopsy-proven osteogenic (11 cases) or Ewing's (nine cases) sarcoma were evaluated by MR imaging on a 0.15-T resistive unit to determine the value of MR in the diagnosis and treatment of these two neoplasms and to develop the best protocol for MR imaging. In all 20 cases, MR identified tumor spread into bone marrow, and it was superior to CT in five cases. Extension of tumor into the soft tissues adjacent to bone was shown better by MR than CT in six cases. Improved anatomic information from MR is the result of the ability to image in the axial, coronal, and sagittal planes. Compared with CT, MR identifies cortical disease but has inferior spatial resolution and defines calcium poorly. MR can be used to monitor tumor response to chemotherapy, and the relationship of tumor to adjacent vasculature can be determined without the use of contrast agents. Two pulse sequences are necessary for maximum display of disease, since, in general, tumor involvement of the bone marrow is best assessed on T1-weighted sequences, and tumor involvement of the soft tissue is best seen on T2-weighted sequences. Additional information about bone-marrow involvement, soft-tissue tumor extent, and the relationship of tumor to blood vessels makes MR a valuable adjunct to CT in the evaluation of these neoplasms.

Adolescent↗