Search PubMed⌕ Search

Biomedical subjects

G E Newman

Publications and source records attributed to G E Newman.

At least 37 records · Page 2Linked to original sources
PubMed1991

Adsorption of fetal surfactant protein SP-B on the human amnion at term and on amniocytes incubated with fetal surfactant in vitro.

Fetal surfactant stimulates the synthesis of prostaglandins by slices of human amnion at term and by a human amnion cell line, and these effects are partly dependent upon surfactant apoproteins. In this paper, methods are described for the purification of surfactant from human amniotic fluid and from post-mortem human lung. A procedure is described for the purification of surfactant protein SP-B from human amniotic fluid, and the sequence of 20 amino acids at the N-terminal has been determined. A monoclonal antibody generated against human lung surfactant has been shown to react with SP-B from amniotic-fluid surfactant, and the presence of SP-B on the surface of the amnion at term has been demonstrated by immunohistochemical methods. It has also been shown that SP-B from surfactant is present on the surface of amniocytes incubated with surfactant in vitro.

Adsorption↗
PubMed1991

Renal vein renins: inability to predict response to revascularization in patients with hypertension.

To determine whether the captopril-stimulated renal vein renin ratio (CSRVRR) could enable identification of patients with hemodynamically significant renovascular lesions who would respond to revascularization, the authors measured CSRVRRs in 143 consecutive patients with hypertension who had been selected because of clinical features suggestive of renovascular hypertension. All patients underwent conventional renal arteriography. Renovascular hypertension was the final diagnosis if revascularization resulted in cure or improvement in blood pressure. Complete data were available for 133 patients. Twenty patients had renovascular hypertension; CSRVRR was greater than 1.5 in 13 of these 20 patients (sensitivity, 65%). However, it was also greater than 1.5 in 54 of the 113 patients without renovascular hypertension (false-positive rate, 47.8%). The positive predictive value of CSRVRR was 18.6%; the negative predictive value, 89.3%. It is concluded that CSRVRR is not sufficiently sensitive to enable prediction of which patients will respond to revascularization and is not specific enough to exclude patients who do not have renovascular hypertension.

Adult↗
PubMed1991

Imaging of the renal arteries: value of MR angiography.

We compared the efficacy of MR angiography with that of conventional angiography for visualizing the renal arteries and detecting renovascular disease. Thirty-three MR angiographic studies, consisting of axial two-dimensional (2-D) phase-contrast, coronal 2-D phase-contrast, and coronal 2-D time-of-flight acquisitions, were performed within 48 hr of conventional arteriography. The studies were done to evaluate possible renovascular hypertension (n = 25) or potential donor nephrectomy (n = 8). The three MR image sets were interpreted independently, in random order by three observers, with regard to the number of renal arteries, degree of vessel visualization, arteriovenous overlap, and presence of renovascular disease. A fourth interpretation was based on the combined axial and coronal phase-contrast image sets. Evaluation was limited to the proximal 35 mm of each renal artery. Renal artery visualization and detection of renovascular disease were more complete with coronal phase-contrast (80% sensitivity, 91% specificity) than with time-of-flight (53% sensitivity, 97% specificity) images. Combined axial and coronal phase-contrast images permitted visualization of the proximal 35 mm of all dominant renal arteries and detection of 13 of 15 stenoses (87% sensitivity, 97% specificity). Our data suggest that biplanar MR angiography has considerable potential as a noninvasive screening technique for the evaluation of renovascular disease.

Angiography↗
PubMed1990

Malpositioned peritoneal dialysis catheters: a critical reappraisal of correction by stiff-wire manipulation.

Tenckhoff peritoneal dialysis (PD) catheter malposition is one of the leading causes of catheter malfunction. Fluoroscopically directed stiff-wire manipulation of malpositioned PD catheters has been advocated as a method of catheter salvage. Two hundred eighty-nine single-cuff PD catheters were placed surgically into 203 patients during this 4-year study. Thirty-three patients developed catheter malfunction attributed to malposition. Forty-eight stiff-wire manipulations were performed on these patients. Thirty-eight (78%) of the manipulations were described as successful at the time of transfer from radiology. However, only 25 (51%) and 12 (25%) resulted in functioning catheters at 1 week and 1 month, respectively. Only 11 of 33 patients who underwent manipulation had functional prolongation of catheter life beyond 1 month. The PD catheter was replaced by a column-disk PD catheter without additional catheter dysfunction in six patients. A second single-cuff Tenckhoff PD catheter was inserted in another six patients. Three of these six catheters again malpositioned. We conclude that stiff-wire manipulation is a useful and safe technique worth using on a limited basis for the initial episode of catheter malposition. Catheters that repetitively malposition should be replaced with a catheter that is resistant to malpositioning.

Adult↗
PubMed1990

A method for evaluating the bronchial circulation. Preliminary observations.

Due to the small size of the bronchial arteries, the bronchial circulation is difficult to study and remains poorly understood. We have utilized single photon emission computed tomography (SPECT) as a noninvasive means of studying the bronchial circulation. Imaging studies were performed in sheep before and after the introduction of a single pulmonary embolus. Digital bronchial arteriograms demonstrated the dilatation of the bronchial artery which is present on studies one week after embolization. SPECT bronchial perfusion scans reveal a wedge of increased activity that corresponds to a wedge of decreased activity on SPECT pulmonary perfusion images. Axial images available with SPECT provide information about regional alterations of bronchial perfusion not readily apparent on bronchial arteriograms.

Animals↗
PubMed1989

Correlation of clinical history with quantitative histology of lower extremity atheroma biopsies obtained with the Simpson atherectomy catheter.

The purpose of this study was to compare the histologic variability of atheromas resected from patients with various risk factors for vascular disease. Twenty-seven plaques obtained using the Simpson atherectomy catheter were studied. The results of this light and electron microscopic study indicate that patients with diabetes mellitus had increased numbers of smooth muscle cells in their plaques (P less than 0.05) and a trend toward denser, less fatty connective tissue matrix (P less than 0.07) when compared with non-diabetics, and that female diabetics had more smooth muscle cells in their plaques than male diabetics (P less than 0.05). The female patients, regardless of risk factors, had more smooth muscle cells in their plaques than male patients (P less than 0.004). Patients with poor distal runoff had more neovascularization of plaque (P less than 0.001). Tobacco use and age did not have statistically significant correlations with histologic patterns.

Arteriosclerosis↗
PubMed1989

Prevention of hemodialysis fistula thrombosis. Early detection of venous stenoses.

Venous dialysis pressures were measured consecutively in 168 chronic hemodialysis patients for 265 patient-years of monitored dialysis. Venous dialysis pressure greater than 150 mm Hg measured by the protocol were considered elevated. Seventy-three patients had elevated venous dialysis pressures and 58 agreed to undergo elective venography (fistulogram). Fifty of 58 patients studied (86%) had significant venous stenoses. A combination of percutaneous transluminal angioplasty (PTA) and surgical revision were used to electively treat these stenoses. Early detection and treatment of these stenoses decreased fistula thrombosis and fistula replacement threefold compared with our earlier experiences. Patients with elevated venous dialysis pressure who were venogramed and treated had an occurrence of fistula thrombosis similar to patients with normal dialysis pressure (0.15 and 0.13 episodes per patient year of dialysis respectively, P = NS). In contrast patients with elevated venous dialysis pressure who refused elective fistulogram and treatment averaged 1.4 episodes of thrombosis per patient year of dialysis (P less than 0.001) compared to both other groups). We conclude that elevated venous dialysis pressure is a reliable method of detecting fistula stenoses and that the elective treatment of these stenoses significantly decreases fistula thrombosis and fistula loss.

Angioplasty, Balloon↗
PubMed1989

Chronic multiple pulmonary emboli. Regional response of the bronchial circulation.

In pulmonary embolism, the bronchial circulation can dramatically increase perfusion to the lung and prevent infarction. The physiology of this response is incompletely understood. The authors studied the regional changes in the bronchial circulation in an animal model after multiple chronic pulmonary emboli to the periphery of one lung. The gross anatomy of the bronchial circulation was studied using Batson's solution to produce vascular casts of the pulmonary and bronchial circulations. These casts were prepared in a normal sheep and in a sheep with multiple chronic microemboli in the periphery of one lung. The normal bronchial arteries are visible as threadlike structures covering the surface of the tracheobronchial tree with ramifications extending to the lung periphery. In a sheep with multiple chronic microemboli, the bronchial arteries supply the pulmonary parenchyma deprived of pulmonary arterial flow. The bronchial arteries following pulmonary arterial embolization markedly dilate and are serpentine.

Animals↗
PubMed1989

Pulmonary thromboembolism: a historical perspective.

The pathophysiology of acute and chronic thromboembolic disease was well documented and understood long before methods of diagnosing the disease with confidence were developed. It should also be noted that heparin, currently the standard therapy for acute venous thrombosis and acute pulmonary embolism, was available before diagnostic imaging studies were developed and in general use. The current diagnostic procedures (venography, Doppler ultrasound, V/Q imaging, and pulmonary angiography) and the various diagnostic algorithms for evaluating patients suspected of having thromboembolic disease are relatively recent developments, but have had a major impact on the treatment of this disease.

History, 19th Century↗
PubMed1989

Pulmonary angiography in pulmonary embolic disease.

Pulmonary thromboembolic disease is a serious and common complication in patients with various medical and surgical diseases. Pulmonary angiography is currently accepted as the "gold standard" for the diagnosis of pulmonary embolism, but its role is still somewhat controversial. This review article attempts to answer some of these controversies by exploring the how, when, what, and where of contemporary pulmonary angiography.

Angiography↗
PubMed1989

Intravenous digital subtraction renal angiography: use in screening for renovascular hypertension.

Intravenous digital subtraction renal angiography (DSRA) has been compared with conventional angiography only in small, selected series of hypertensive patients. The authors prospectively examined with intravenous DSRA 94 patients at increased risk for renovascular hypertension and compared these studies with conventional angiography. A stenosis of at least one main renal artery was identified with intravenous DSRA in 22 patients and confirmed in 20 patients. No significant stenoses were seen with conventional angiography in any of the 64 patients in whom lesions were not seen with intravenous DSRA. Since inadequate DSRA studies were considered positive for renal artery stenosis, the sensitivity of intravenous DSRA was 100% (25 of 25); specificity, 93% (64 of 69); positive predictive value, 83% (25 of 30); and negative predictive value, 100% (64 of 64). The authors conclude that intravenous DSRA is a sensitive test for identifying stenosis of the main renal arteries and is appropriate to use as a screening test among patients at increased risk for renovascular hypertension.

Adult↗
PubMed1989

Effect of lipid and protein fractions from fetal pulmonary surfactant on prostaglandin E production by a human amnion cell line.

Discs of amnion and choriodecidua prepared from women delivered at term were incubated with and without surfactant prepared from human amniotic fluid and the output of prostaglandin E (PGE) was estimated by radioimmunoassay. Surfactant stimulated the release of PGE in both tissues. The stimulatory effect was characterized further using cultured human amnion cells. The effect was dose- and time-dependent and required for full expression both protein and lipid components of surfactant. Arachidonate constituted about 3.5% of the fatty acids of fetal surfactant phospholipids. These findings suggest that surfactant is an important source of arachidonate for intrauterine PG synthesis.

Amnion↗
PubMed1988

Surgical renal artery reconstruction after percutaneous transluminal angioplasty.

Percutaneous transluminal renal angioplasty (PTRA) is a controversial treatment for renal artery stenosis. This article discusses whether or not a prior attempt at PTRA compromises a subsequent elective or emergent surgical revascularization. Thirteen patients had surgical renal artery reconstruction after one or more PTRAs. Eight of the patients were treated because of atherosclerotic renal artery disease whereas five had a form of fibromuscular dysplasia. Five patients had renal artery injury directly related to the angioplasty. Four of these kidneys were saved. Eight patients were treated from 6 to 920 days after PTRA because of recurrent stenosis or occlusion of the renal artery. Only one of these kidneys was lost, an attempt at revascularization of a small kidney that failed to resume function. A prior attempt at PTRA did not compromise the ability of subsequent surgical revascularization to ameliorate hypertension. We conclude that surgical renal revascularization is not made less likely to succeed by a previous attempt at PTRA; even if the renal artery is thrombosed or perforated during the procedure, a reasonable chance of renal salvage is obtained by immediate surgical revascularization.

Angioplasty, Balloon↗
PubMed1988

Surfactant stimulates prostaglandin E production in human amnion.

Discs of human amnion prepared from nine women delivered by elective caesarean section at term were incubated with and without purified human amniotic fluid surfactant (9 micrograms lipid P/ml), and the output of prostaglandin E (PGE) was estimated by radioimmunoassay. Surfactant stimulated the release of PGE from 3.8 (SD 2.9) to 5.4 (SD 2.5) pmol/mg dry weight/3 h (P less than 0.01). Arachidonic acid accounted for 2% of the fatty acids of surfactant lecithin. These results show that surfactant has a stimulatory effect on amniotic PGE production and that it is an important source of arachidonic acid in amniotic fluid.

Amnion↗
PubMed1988

Peripheral artery atherectomy: description of technique and report of initial results.

Percutaneous transluminal atherectomy has been developed for treatment of peripheral artery stenoses. The atherectomy catheter is inserted through a sheath, and the resection window of the catheter is positioned adjacent to the vascular stenosis. The balloon is inflated, and the motor-driven cutting blade advanced. The balloon is then deflated, the catheter withdrawn, and the atheromatous material, which resembles the resected material of an endarterectomy, removed from the catheter. This process is repeated until the resection provides an adequate lumen. To date, 12 arterial lesions (three common iliac, two external iliac, four superficial femoral, and three popliteal artery) in ten patients have been resected with excellent angiographic results. The conditions of seven patients who underwent atherectomy for relief from claudication were improved by the criteria of ankle/arm ratios and/or claudication distance. Three patients successfully underwent atherectomy for limb salvage. More data on long-term patency and restenosis rates are needed before the ultimate role of atherectomy in the management of peripheral artery disease can be determined.

Adult↗
PubMed1987

Percutaneous intervention in the solitary kidney.

The solitary kidney, either after nephrectomy or on a congenital basis, may be impaired by infection, stones, obstruction, and trauma. Because of the possibility of further renal compromise by damage of the remaining nephron units, there is reluctance to utilize percutaneous techniques in cases of solitary kidney, and surgery is often used as an alternative. We report 15 cases of solitary kidney in which interventional radiologic techniques (i.e., percutaneous nephrostomy, ureteral stenting, ureteral dilatation, and stone extraction) were attempted for the preservation of renal function, either as a permanent solution or as a temporizing maneuver prior to definitive therapy. In each case, these goals were achieved and there were no complications.

Adolescent↗
PubMed1987

Intravenous digital subtraction angiography in the evaluation of potential renal donors.

Of 65 surgically removed donor kidneys intravenous digital subtraction angiography demonstrated accurately the number of renal arteries in 58 (89 per cent). All accessory vessels missed at digital subtraction angiography were small and their presence did not interfere with successful transplantation in those donated. Of 50 surgically removed donor kidneys examined with conventional aortography only before the routine use of intravenous digital subtraction angiography the number of renal arteries was demonstrated accurately in 46 (92 per cent). Intravenous digital subtraction angiography offers advantages over conventional aortography, including most importantly the routine performance on an outpatient basis, and decreased film cost and examination time. Although the accuracy of conventional aortography (92 per cent) in detecting the number of renal arteries is slightly greater than that for intravenous digital subtraction angiography (89 per cent), the advantages of the digital examination justify its use as the initial examination for the potential renal donor. Conventional aortography can be reserved for use in patients with equivocal or technically inadequate digital examinations.

Angiography↗