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Biomedical subjects

R Walden

Publications and source records attributed to R Walden.

At least 73 records · Page 4Linked to original sources
PubMed1986

Percutaneous transluminal angioplasty. A suggested method for analysis of clinical, arteriographic, and hemodynamic factors affecting the results of treatment.

Sixty-nine percutaneous transluminal angioplasties (PTAs) were performed in the iliac and the femoral arteries of 54 patients. The main factors that might affect the results were reviewed: associated diseases, severity of ischemic symptoms, location and type of lesions (stenosis or occlusion and their length), and presence of disease distal to the site dilated. The vascular status of the patients in our series was more severe than in most others. Improvement at follow-up (average 15 months) was maintained in 74% of 66 radiographically successful PTAs. Poor runoff was the only factor found to affect the outcome deleteriously. Intra-arterial pressure measurements performed during the procedure and vascular laboratory studies were most valuable in assessing immediate and long-term results. Wide variations in results of PTA published in the literature are due to differences in methods of selection, evaluation, and reporting. A plea is made for future presentations of PTA series in an analyzable and comparable way, including and correlating all relevant variables as in the model suggested by the present study.

Adult↗
PubMed1985

Comparative toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in four (sub)strains of adult male rats.

Four (sub)strains of adult male rats were given single oral doses of various concentrations of TCDD to establish and compare the oral 30-day LD50 values. The strains of rats were Fischer (F/334N) supplied by Harlan Industries, Frederick Cancer Research Center, and Charles River Breeding Laboratories; and CD supplied by Charles River Breeding Laboratories. The Charles River/Fischer rats were most sensitive to TCDD (LD50 = 164, 95% confidence limits 104-217 micrograms/kg), the Frederick/Fischer and Charles River/CD rats were moderately sensitive to TCDD (LD50 = 303, 250-360; and 297, 240-360 micrograms/kg, respectively), and the Harlan/Fischer rats were most resistant to TCDD (LD50 = 340, 281-409 micrograms/kg). The mean times of death were from 24.5 +/- 1.0 to 28.3 +/- 0.5 days and the percentage body weight loss at death was 37.4 +/- 1.2 to 42.7 +/- 1.3%. One week after exposure of the Charles River/Fischer animal to 45 micrograms TCDD/kg (1/4 the established 30-day LD50 dose), the same serum profile was induced as previously observed in the Harlan/Fischer rat, which includes hypoglycemia, hypertriglyceridemia, and hypercholesterolemia. These results emphasize the importance of indicating the precise dose, strain of rat, and time after dosing before termination in reporting the effects of TCDD on a particular biological response.

Animals↗
PubMed1985

Left renal vein division in abdominal aortic aneurysm operations. Effect on renal function.

We examined the effect of left renal vein (LRV) division during abdominal aortic aneurysm operations on renal function during the recovery period. Fifteen patients with LRV division were compared with 26 patients in whom the LRV was not ligated. These two groups of patients did not differ significantly in any of their preoperative characteristics, operative management, or postoperative complications. Preoperative, highest postoperative, and predischarge levels of plasma urea and creatinine, as well as urinary sediment, were compared in both groups. Left renal vein division could not be implicated as a cause of renal function deterioration and was found to be a safe, useful adjunct to abdominal aortic aneurysm surgery.

Adult↗
PubMed1985

Distribution and symmetry of arteriosclerotic lesions of the lower extremities: an arteriographic study of 200 limbs.

Lower-extremity arteriograms of 100 candidates for vascular surgery were reviewed. All the arteries in the 200 limbs were visualized and graded as normal, irregular, stenotic, or occluded. The occurrence of hemodynamically significant disease (stenosis or occlusion) was markedly different in various arteries: iliac--37%, common femoral--9%, superficial femoral--58%, deep femoral--19%, popliteal--17.5%, tibialis anterior--27.5%, tibialis posterior--28.5%, and peroneal--16.5%. A remarkable symmetry was observed between the two lower limbs. In 53-76% of contralateral vessels the arteriographic picture was identical. When one degree of difference in arteriosclerotic involvement was allowed, the symmetry increased to 80-96%.

Angiography↗
PubMed1985

Persistent sciatic artery: a case report.

Persistence of the embryonic sciatic artery is a rare vascular anomaly with only 52 documented cases, of which only 19 had angiographic studies. We describe a patient with angiographic demonstration of persistence of a left sciatic artery associated with arterial anomalies of the opposite limb. The embryology radiological findings and clinical significance are discussed.

Angiography↗
PubMed1985

Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and fasting on body weight and lipid parameters in rats.

This study compared the effect of fasting (feed deprivation) and the effect of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on body weight and on key lipid parameters. The time-course study indicated a statistically significant (p less than 0.05) body weight loss in the TCDD-exposed rats 5 days after the oral administration of corn oil with TCDD (60 micrograms/kg body wt). Animals demonstrated a 10% body weight decrease either 1 week after this TCDD administration or after 72 hr of fasting. Marked increases in serum triglyceride and cholesterol were observed only in the TCDD-exposed rats, but not in the 0- or 72-hr fasted control rats. These results indicated that some body weight loss and decreased feed consumption occurred after TCDD exposure, but that the metabolic response, with respect to serum lipid metabolism, was not that of a control rat that had lost a similar amount of body weight due solely to fasting.

Administration, Oral↗
PubMed1983

Noninvasive intraoperative assessment of arterial reconstruction. Experimental validation of the role of central and regional hemodynamics.

We developed an experimental model of graded arterial stenosis to emulate conditions that might be encountered immediately following arterial grafting. Noninvasive measurements of systolic BP and limb blood flow were recorded with a Doppler probe and segmental air plethysmography, respectively, under conditions of different cardiac output and local arterial resistance. These measurements were correlated with direct intra-arterial pressure recordings and flow measurements taken with an electromagnetic flowmeter. There was an excellent correlation between noninvasive and intra-arterial measurements of systolic pressure over a range of cardiac outputs and degree of arterial stenosis. Pulse volume recordings correlated with direct measurements of blood flow at high and baseline cardiac outputs, but the calibration of pulse volume amplitude varied between cuff applications in this canine model. Noninvasive intraoperative monitoring techniques can faithfully represent known physiologic responses to graded arterial stenoses, irrespective of a high cardiac output or peripheral vasodilation.

Animals↗
PubMed1983

Development of rat liver and colon substrate cycle enzymes in offspring with and without prenatal exposure to a carcinogenic dose of 1,2-dimethylhydrazine.

Pregnant F-344 rats were exposed by intubation to a single dose (35 mg/kg) of 1,2-dimethylhydrazine dihydrochloride or to an acetate buffer on day 14 of gestation. A detailed examination of the effects of this dose of 1,2-dimethylhydrazine on brush border enzymes in the offspring was performed. Changes in the liver and colon levels of the alpha-glycerophosphate and malate/aspartate substrate cycle enzymes were measured during the development; at days 17 and 20 of gestation and at 2, 6, 13, 20, 27, 55, 110 days and 1 year after birth. It is concluded that metabolic energy enzymes, glutamate oxaloacetate transaminase and malate dehydrogenase, are more sensitive to 1,2-dimethylhydrazine treatment than are the brush border hydrolases or NAD- and Fp-linked alpha-glycerophosphate dehydrogenases.

1,2-Dimethylhydrazine↗
PubMed1982

Effects of polychlorinated biphenyls on the development of intestinal and serum marker enzymes.

The effects of polychlorinated biphenyls (PCBs) on the development of several intestinal and serum marker enzymes have been studied. The three congeners 4-monochloro (1-CB), 3, 4, 3',4'-tetrachloro (4-CB), and 2, 4, 5, 2', 4, 5'-hexachloro (6-CB) biphenyl were administered orally to pregnant rats on d 8, 11, 13, 15, and 18 or gestation. 1-CB and 6-CB were intubated at doses of 30 mg/kg.d (total dose, 150, mg/kg) and 4-CB was administered at 3 mg/kg-d (total dose, 15 mg/kg). Levels of intestinal alkaline phosphatase, monoamine oxidase, and Na+, K+-adenosin-5'-etriphosphatase and levels of serum alkaline phosphatase, sorbitol dehydrogenase, and beta-hydroxybutyrate dehydrogenase were measured in the dams after weaning and in their offspring at -1, 6, 20, and 55 d of age. Intestinal alkaline phosphatase activity was elevated at the later postnatal stages in the 1-CB group and depressed at 55 d in the 4-CB group, whereas serum alkaline phosphatase levels were markedly depressed prenatally and postnatally in the 4-CB and 6-CB groups, respectively, Intestinal monoamine oxidase levels were markedly increased in the 6-CB group at -1, 6, and 20 d of age and significantly depressed in the 4-CB animals at -1 and 55 d of age. There was an increase in monoamine oxidase activity in the 4-CB group at 6 d. The 1-CB group exhibited depression of monoamine oxidase levels at 6 and elevation at 20 and 55 d. Intestinal Na+, K+-ATPase levels were elevated throughout development in the 1-CB animals and at -1 and 6 d in the 4-CB group. The 6-CB animals showed elevated levels of Na+, K+-ATPase only at 6 d. Serum beta-hydroxybutyrate dehydrogenase and sorbitol dehydrogenase were induced prenatally in the 4-CB animals but enzyme activities decreased to normal by 55 d of age. Significant depression of activity was evident in the 1-CB and 6-CB groups at -1 d in both enzymes. Dams in the 1-CB group showed significant changes in intestinal monoamine oxidase, serum sorbitol dehydrogenase, and serum alkaline phosphatase. Serum levels were elevated in the 4-CB group. Activities of intestinal enzymes remained unchanged in the 4-CB group. All maternal enzyme levels monitored were not significantly changed in the 6-CB group.

Alkaline Phosphatase↗
PubMed1982

Iatrogenic complications in surgery. Five years' experience in general and vascular surgery in a University Hospital.

Advances in medicine that have led to more sophisticated methods of diagnosing, treating and monitoring patients take an ever increasing toll in iatrogenic complications. It may be argued that the net effect is an improvement in care, but it is self-evident that minimizing iatrogenic complications will increase the benefit to the patients of the ever increasing complex methods of treatment. Iatrogenic complications tend to be sporadic and varied in nature, and are difficult to study as a group. Psychological and medicolegal problems add to this difficulty. However, if the incidence of iatrogenic complications is to be decreased, a concerted effort has to be made to study them. Them report deals with an effort.

Arteries↗
PubMed1981

Anatomic localization of atherosclerotic lesions by hemodynamic tests.

Use of noninvasive tests to assess the severity of lower-extremity occlusive lesions is generally accepted. To evaluate the effectiveness of noninvasive vascular-laboratory tests in locating atherosclerotic lesions, the results of hemodynamic studies in 100 patients were reviewed by both skilled observers and a vascular computer, and compared with angiograms. The results of the comparison suggest a remarkable sensitivity of the vascular-laboratory tests in locating significant arterial obstructions, and underscore that the great predictive value of a negative results gives the physician reliable information on the patency of a given arterial segment. Computer interpretation proved less accurate than that of the vascular-laboratory personnel.

Adult↗
PubMed1981

Synthesis of Chloroplast Proteins during Germination and Early Development of Cucumber.

Cell-free protein synthesizing systems have been used to study the developmental changes in the synthesis of chloroplast proteins in the cotyledons of cucumber seedlings grown in the light or in the dark. Escherichia coli and wheat germ in vitro protein synthesizing systems have been used to assay the changes in the levels of the mRNA's coding for ribulose 1,5-bisphosphate carboxylase (RuBPCase). The large subunit of cucumber RuBPCase has been identified among the translation products of the E. coli system. The wheat germ system translates the cucumber mRNA coding for the small subunit of RuBPCase to produce a 25,000 molecular weight precursor polypeptide. Plastids isolated from light-grown cotyledons were used to study developmental changes in their capacity to synthesize protein. The data obtained indicate that in the light there is an initial 48-hour period of accumulation of the mRNA's coding for the large and small subunits of RuBPCase, coupled with an increase in the capacity of the isolated plastids to synthesize protein. This is followed by a decline. This decline is not reflected in the accumulation of RuBPCase in the cotyledons which remains constant over the period of study.

Journal Article↗
PubMed1980

Matched elastic properties and successful arterial grafting.

Clinical results from medium- and small-caliber arterial bypass grafts are unsatisfactory. Since elastic properties of grafts tested experimentally have been correlated with patency results, the compliance of the human femoral artery was compared with grafts currently in use: human saphenous vein (HSV), knitted Dacron (DAC), glutaraldehyde-treated umbilical cord vein (DBM), bovine heterograft, and expanded polytetrafluoroethylene (PTFE). This was correlated with clinical patency data for the different conduits in the femoropopliteal position. Increased patency correlated with a decreasing disparity between host artery and graft compliance. After two years, patency rates of the more compliant materials (HSV, DBM) exceeded 80%, while less than 45% of the incompliant grafts (DAC, PTFE) remained patent. Thus, clinical performance with synthetic grafts might be improved by use of prostheses in which the viscoelastic characteristics match those of arteries more closely.

Actuarial Analysis↗