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Biomedical subjects

A B Voorhees

Publications and source records attributed to A B Voorhees.

At least 19 recordsLinked to original sources
PubMed1985

Arterial regenerative activity after prosthetic implantation.

Factors modifying arterial regenerative activity were evaluated by replacing adult rabbit aortas with either absorbable polyglycolic acid (PGA) or nonabsorbable Dacron prostheses, 3.5 mm in internal diameter by 24 mm in length, woven to identical specifications including pore size, wall thickness, and elastic modulus, and were followed up for 12 months. At death, 48 PGA and 20 Dacron specimens were studied grossly and by arteriography, light microscopy, scanning and transmission electron microscopy, and by bursting strength determinations. There were no aortic-related deaths or transaortic hemorrhages. Both materials elicited a surrounding inflammatory reaction containing macrophages which transgressed the interstices of only the PGA prostheses. Between two and four weeks, circumferentially oriented smooth-musclelike myofibroblasts proliferated in the PGA inner capsule yielding a neointima 3.2 times thicker than Dacron's. Early ultrastructurally primitive cells progressively differentiated into these smooth-musclelike myofibroblasts. The few myofibroblasts later appearing with Dacron were radially oriented. After one month proliferation stopped in both groups and neointimal thickness became constant. The luminal surface in the PGA group was endothelial-like but was fibrinous in the Dacron group. All specimens withstood saline infusion at three to five times systolic pressure. These studies demonstrate great arterial regenerative potential and suggest hemodynamic and intercellular mitogens controlling it.

Animals↗
PubMed1984

Simple methods for direct antibiotic protection of synthetic vascular grafts.

Two simple methods for direct antibacterial protection of synthetic vascular grafts were investigated. In the first protocol the highly protein-bound antibiotics nafcillin (90% protein bound), cefazolin (80%), and cefamandole (70%) were added directly to preclotting blood. Knitted Dacron grafts preclotted in the presence of one of these drugs absorbed significant amounts. Although at high concentrations these antibiotics exhibited anticoagulant effects, significant antibacterial protection was obtained at lower antibiotic levels. Washing treated grafts for 6 hours failed to eliminate the antibacterial activity. Antibiotics remained on the grafts for at least 96 hours. In the second protocol knitted Dacron grafts were soaked in a suspension of silver-pefloxacin, a silver-nalidixic acid analogue with intense antistaphylococcic activity. Using 110Ag-labeled complexes, significant antibiotic activity was documented on the graft after 19 days of washing. Four nafcillin-treated prostheses, six silver-pefloxacin-coated grafts, and 11 control grafts were interposed in the infrarenal aorta of dogs and immediately challenged with an intravenous infusion of 1 X 10(7) Staphylococcus aureus. None of the four nafcillin-treated grafts was infected at 3 weeks. One of the six silver-pefloxacin-coated grafts grew staphylococci, and 9 of 11 controls had positive graft cultures for Staphylococcus when harvested. These studies suggest that prosthetic grafts can be simply coated at the time of implantation with antibiotics selected for appropriate binding and antibacterial characteristics to obtain an infection-resistant prosthesis.

Animals↗
PubMed1983

Vascular complications associated with percutaneous intra-aortic balloon pumping.

A percutaneous intra-aortic balloon pump (PIABP) was inserted in 112 patients. Successful placement was achieved in 102 patients, 67 of whom survived long enough to have the device removed. Vascular complications related to the PIABP were noted in 15 patients. Reversal of ischemic signs followed PIABP removal in six patients, but nine required femoral artery exploration for thrombectomy, repair of femoral laceration, or repair of false aneurysm. No patient died as a result of PIABP or correction of associated vascular complications, though five of the patients with vascular problems died of cardiac complications. Nine of ten survivors in this group were asymptomatic, and one had persistent paresthesias six months postoperatively. Most clinically significant vascular complications were due to the technique of balloon removal, and several modifications that were effected recently are expected to decrease the incidence of complications requiring surgical intervention.

Angina Pectoris↗
PubMed1983

Effect of CO2 laser on the luminal surface of blood vessels in vivo.

The use of lasers as surgical tools may open up new possibilities for the treatment of atherosclerotic occlusive vascular disease. However, basic information regarding the effect of laser radiation to the lumen of normal blood vessels is needed prior to clinical application. This work investigates the nature of the CO2 laser-induced vascular wound and the time course of its healing in the rabbit aorta. The chief short-term problem with CO2 laser radiation of the luminal surface of blood vessels is thrombosis.

Animals↗
PubMed1981

Angioplasty for femoral artery occlusion: comparison with surgery.

Forty-six patients with superficial femoral artery occlusions (range, 1-20 cm) had percutaneous transluminal angioplasty. The primary success rate was 76% with a late closure in six patients. Life table analysis showed a 1 year patency of 56.8%, maintained at 2 years among the group in whom the successful was 4 cm, while in those in whom the lesion was not crossed, it was 9 cm. Over the same period, 133 femoropopliteal bypass grafts were performed. The patients were comparable as to runoff, incidence of diabetes, and distal ischemia. The 1 year patency was 60.2% and the 2 year patency, 42.1%, largely because of the poor performance of grafts other than saphenous vein. Angioplasty seems to be the treatment of choice for short segment occlusions, and should be used in longer occlusions if saphenous vein is not going to be used.

Angioplasty, Balloon↗
PubMed1979

The nonportal origin of the factors initiating hepatic regeneration.

To determine the site of origin of the factors that initiate deoxyribonucleic acid (DNA) synthesis in the liver after partial hepatectomy, normal rats were cross-circulated with totally hepatectomized rats. Half of the hepatectomized rats had also undergone excision of all of the portal organs. After 48 hours of cross-circulation, active DNA synthesis and other evidences of hepatic regeneration were found in normal rats cross-circulated with the hepatectomized portally eviscerated rats. This demonstrates that a blood-borne factor that does not arise from the portal organs is capable of initiating hepatic regeneration. When a normal rat was cross-circulated with a hepatectomized rat with the portal organs still present, hepatic regeneration occurred but was significantly less than when the portal organs had been removed. It is postulated that under these experimental conditions portal factors from the normal rat have a permissive role that allows active regeneration when initiating factors are furnished from the hepatectomized rat. Additional portal organs in the hepatectomized rat decreased DNA synthesis, possibly by alterations of the insulin/glucagon ratio.

Animals↗
PubMed1979

The endoscopy corner: reversible ischemic colitis--correlation of colonoscopic and pathologic changes.

Ischemic colitis is a well described complication following distal aortic replacement. The diagnosis is typically made by correlating clinical signs such as the occurrence of abdominal pain and bloody diarrhea with supporting radiographic changes. In this report, the diagnosis of ischemic colitis was confirmed on the basis of colonoscopic and associated histopathological findings. Colonoscopy is a useful technic in establishing the diagnosis of ischemic colitis, especially in patients whose clinical condition makes barium enema not feasible.

Aged↗
PubMed1976

Immediate endoscopic diagnosis of upper gastrointestinal bleeding. Its accuracy and value in relation to associated pathology.

Two hundred sixty-two patients with active upper gastrointestinal (GI) bleeding underwent panendoscopy between July 1970 and March 1973. There was 100% accuracy of endoscopic diagnosis as to the anatomical site of bleeding; the etiopathologic definition was 94.7% accurate. The series was divided into two groups, 116 with "liver disease" and 146 with "no liver disease." There were 107 patients with varices: 21 fell into no liver disease (small varices) and 86 into liver disease (39 small and 47 large varices). All had associated gastritis. Three endoscopic bleeding patterns were identified in the liver disease group. Only 27% of the patients in the liver disease group with varices (cirrhotics) had frank variceal hemorrhage, whereas 57% bled from hemorrhagic gastritis. The diagnostic unit provided early diagnosis, meaningful therapy, organized data gathering, and rough estimates of ultimate prognosis.

Endoscopes↗
PubMed1976

Predictability of surgical response in renovascular hypertension.

One hundred sixteen patients underwent operation for renovascular hypertension from 1962 through 1975; 64% had aortorenal reconstruction and 36% had nephrectomy. Sixty-six percent were cured and 19% were improved. Rapid sequence intravenous pyelography, radioisotope renography, and renal arteriography were equal in ability to detect renovascular hypertension. Bilateral renal biopsy specimens had excellent prognostic value when performed in a graded semiquantitative manner. Plasma renin activity was the most consistently useful criterion for prediction of surgical cure if the following requirements were used: (1) elevated peripheral plasma renin activity, (2) elevated renin from the affected kidney, and (3) suppressed renin secretion from the contralateral kidney. An angiotensin II antagonist, saralasin acetate, used in six patients before operation in an attempt to identify those whose hypertension depended on angiotensin II activity, produced a depressor response correlating well with the surgical result.

Adolescent↗
PubMed1976

Factors influencing patency of femoropopliteal artery bypass grafts.

An analysis of 276 femoropopliteal bypass procedures performed in 264 patients at the Columbia-Presbyterian Medical Center over the past two decades showed a direct relationship of graft patency to preoperative popliteal artery runoff. Fuctional results were better than patency results. Sympathectomy and anticoagulation did not improve graft patency. The risk of amputation is outweighed by the benefits of restoration of blood flow to the ischemic extremity by a byass procedure.

Amputation, Surgical↗
PubMed1976

Aneurysm of the aorta treated by wiring: case report of a 38-year survival.

A patient with a syphilitic aneurysm of the aorta treated by the insertion of wire is presented. The patient remained well for almost 40 years, but finally succumbed after rupture. The autopsy findings are discussed. To our knowledge, this represents the longest reported survival after treatment of an aortic aneurysm by wiring.

Aged↗
PubMed1975

Hepatic regeneration in the absence of portal viscera.

In an effort to investigate the influence of portal factors on hepatic regeneration in the rat and to clarify glucagon's apparent regulatory role, a rat preparation was developed which was totally devoid of portal viscera and thus deficient in all possible hepatotrophic substances of portal origin. It was found that, following partial hepatectomy, such an eviscerate rat was able to undergo hepatic deoxyribonucleic acid (DNA) synthesis, but the peak DNA synthetic response was significantly delayed by such portal deprivation. As demonstrated by a group of rats with intact portal viscera, but with a portacaval shunt, reduction of blood supply to the hepatic remnant by diversion of portal flow accounted for only a portion of the delay. The remainder of the delay encountered in the eviscerate group was attributed to the deprivation of specific portal substances. Since glucagon supplementation administered to the deficient eviscerate animal restored peak DNA synthesis to the time of its appropriate shunted control, this hepatotrophic substance is a major portal factor modifying the response to partial hepatectomy. Evidence is cited which suggests that glucagon's influence on DNA synthesis is mediated through the formation of cyclic adenosine monophosphate (AMP) and subsequent histone phosphorylation.

Animals↗