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R S Greco

Publications and source records attributed to R S Greco.

At least 37 records · Page 2Linked to original sources

Integrins, adhesion molecules and surgical research.

Integrins and adhesion molecules are a group of closely related glycoproteins expressed by a wide variety of cells. In vitro experiments have shown these families of cell surface receptors to be essential to the interactions between the cytoskeleton and the extracellular matrix. Although the designations of families of integrins and adhesion molecules is complex, this review attempts to present an organization in which the result is to provide surgeons with an understanding of their structure and function. This is particularly important because integrins and adhesion molecules have a critical role in such diverse processes as embryogenesis, inflammation, wound healing, thrombosis, transplantation and oncogenic transformation. It is, therefore, highly probable that they will be critical to future advances in surgical research and ultimately in surgical practice. It should be remembered that this area of investigation is so dynamic that the interval involved in publication of this article will in itself be characterized by a plethora of publications in the basic science and surgical literature, which warrants careful attention.

Animals↗

The adherence of endothelial cells to Dacron induces the expression of the intercellular adhesion molecule (ICAM-1).

The intercellular adhesion molecule (ICAM-1) is a glycoprotein expressed by endothelial cells activated by cytokines. The lymphocyte-function-associated antigen (LFA-1) is an integrin expressed by activated white blood cells. Together, this receptor-ligand pair is responsible, in part, for the localization of neutrophils at sites of inflammation. Using an in vitro model, the authors studied the binding of antibodies against ICAM-1 by human saphenous vein endothelial cells (HSVEC) adherent to Dacron and control cultureware. After adherence to Dacron pretreated with fibronectin, 24% more HSVEC-bound antibody against ICAM-1 compared with HSVEC on controls. In contrast, 90% more HSVEC adherent to Dacron incubated with whole blood bound anti-ICAM-1 antibodies. These cells bound 17.7-fold greater amounts of antibody compared with HSVEC on controls. Pretreating Dacron with plasma resulted in no increase in antibody binding compared with control. Our studies suggest that the cellular components of blood in contact with Dacron create a microenvironment that activates HSVEC and enhances ICAM-1 expression. Induction of this adhesion molecule may play a pivotal role in the migration and localization of leukocytes at the site of the vascular prosthesis.

Antigens, CD↗

Desmoplasia in benign and malignant breast disease is characterized by alterations in level of mRNAs coding for types I and III procollagen.

Desmoplasia, the formation of excessive connective tissue surrounding some neoplasms, is a well documented, but incompletely understood phenomenon. To characterize the fibrotic response in benign breast conditions and malignancy, we examined the steady state levels of mRNA coding for types I and III procollagen in mild fibrocystic changes, in fibroadenoma, and in infiltrating ductal carcinoma. The results indicate that in mild fibrocystic change there is a relative increase in type III procollagen mRNA. In contrast, fibroadenoma and carcinoma are characterized by increased levels of type I procollagen mRNA.

Adult↗

Differential production of interleukin 1 on the surface of biomaterials.

The production of cytokines on the surface of surgical biomaterials plays a major role in their biocompatibility. Membrane-associated interleukin 1 (mIL-1) is a cytokine found on the surface of macrophages activated by biomaterials. To better understand the host-foreign body interaction, we quantitated the production of mIL-1 on the surface of two materials commonly used in surgery, expanded polytef (ePTFE) and silicon elastomer (SE). The mean (+/- SD) level of mIL-1 produced by adherent cells to ePTFE significantly decreased from day 2 (13,746 +/- 3630 cpm per disk) compared with day 7 (2828 +/- 1304 cpm per disk). However, the level of mIL-1 produced by ePTFE-adherent cells was still markedly greater than the level of mIL-1 produced by cells adherent to SE (1877 +/- 1028 vs 1595 +/- 822 cpm per disk). These results indicate that ePTFE and SE elicit a differential host response in terms of cytokine production. This study may enhance our understanding of the cellular events on the surface of biomaterials that underlie clinical observations.

Animals↗

Failure of demonstrated clinical efficacy of antibiotic-bonded continuous ambulatory peritoneal dialysis (CAPD) catheters.

Previous in vitro, in vivo, and a preliminary clinical report have demonstrated efficacy of noncovalently bonding antibiotics to the surface of continuous ambulatory peritoneal dialysis (CAPD) catheters in decreasing infectious complications. A larger prospective randomized clinical trial was completed. Eighty-six patients with chronic renal failure were enrolled in the study and randomized to receive either a surfactant treated or untreated control catheter. All catheters were soaked in cefoxitin at the time of insertion. Groups were comparable in terms of pre-existing illnesses, age, and gender. No differences were shown in the incidence of catheter-tract infections, peritonitis or mechanical complications. There was also no differences in microbiologic culture results. Therefore, it is concluded that this clinical trial did not demonstrate a reduction in catheter-related infectious complications by antibiotic bonding.

Bacterial Infections↗

A reappraisal of prophylactic mastectomy.

The concept of prophylactic mastectomy was nurtured in the shadow of the radical mastectomy. It evolved as preferable to the mutilation caused by the procedure. It developed during a time when the difference between benignancy and malignancy was not as clear and when patients with benign disease were thought to be at significant risk. The idea of surgical prophylaxis accompanied by a superior cosmetic result, in comparison to the radical mastectomy is a noble one. In retrospect, however, it is clear that the indications were ill defined, based often on unfounded risk and predicated on patient and physician anxiety. The scope of risk in carcinoma of the breast has been narrowed, with new information identifying only specific subsets of women with proliferative types of benign disease as more susceptible to the subsequent development of carcinoma. Extensive reviews of material taken at biopsy that had been validated longitudinally have provided data to substantiate this contention. The concept of familial high risk must take into account the number of affected family members, at age diagnosis, menopausal status and bilaterality. The majority of indicants that motivated and propitiated the performance of the bulk of prophylactic mastectomies have lost their relevance. Prophylactic mastectomy for carcinoma, therefore, can perhaps be reserved for women with biopsy-proved, high-risk lesions or an exceptional familial risk, or both, or hereditary risk. Such women must choose for themselves and accept the uncertainty of hypothetic risk reduction, life-long continued surveillance and an altered body image. Guiding patients in the decision should involve a multidisciplinary team composed of a surgical oncologist, geneticist, pathologist, psychotherapist and plastic surgeon. As a concept, the reduction of risk is appealing, but remains yet to prove itself superior to rigorous clinical surveillance with high-quality mammography. The experience reflected in the literature of a seemingly low rate of subsequent carcinoma cannot be judged, because it seems that operations were applied indiscriminantly to patients selected by unknown means and from an unknown population pool. Success based on protecting those not at increased risk only invalidates the operation further. Most surgical and medical oncologists recognize that carcinoma of the breast is either localized or disseminated at the time of the initial diagnosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Breast Neoplasms↗

Whipple operation revisited.

The Whipple procedure traditionally is associated with an operative mortality of 20 to 25 percent. As a result, percutaneous and endoscopic techniques have been advocated to alleviate symptoms in patients with periampullary carcinoma. Now, dramatic reductions in operative mortality rates have been reported. Since radical pancreaticoduodenectomy is the only treatment for cure, a re-evaluation of the role of this procedure is warranted.

Adenocarcinoma↗

Binding of tissue plasminogen activator to vascular grafts.

Tissue plasminogen activator labeled with radioactive iodine (125I-tPA) was immobilized on vascular prostheses chemically modified with a thin coating of water-insoluble surfactant, tridodecylmethylammonium chloride (TDMAC). Surfactant-treated Dacron, polytetrafluoroethylene (PTFE), silastic, polyethylene and polyurethane bound appreciable amounts of 125I-tPA (5-30 micrograms 125I-tPA/cm2). Upon exposure to human plasma, the amount of 125I-tPA bound to the surface shows an initial drop during the first hour of incubation, followed by a slower, roughly exponential release with a t 1/2 of approximately 75 hours. Prostheses containing bound tPA show fibrinolytic activity as measured both by lysis of clots formed in vitro, and by hydrolysis of a synthetic polypeptide substrate. Prior to incubation in plasma, tPA bound to a polymer surface has an enzymic activity similar, if not identical to that of the native enzyme in buffered solution. However, exposure to plasma causes a decrease in the fibrinolytic activity of both bound tPA and enzyme released from the surface of the polymer. These data demonstrate that surfactant-treated prostheses can bind tPA, and that these chemically modified devices can act as a slow-release drug delivery system with the potential for reducing prosthesis-induced thromboembolism.

Antigens↗

The effect of viable omentum on early bile leakage and healing of liver lacerations.

In order to determine if omental tissue accelerates the healing of liver lacerations, simulated bile leakage and collagen biosynthesis were studied in 53 rabbits. After creating a standardized complex liver laceration, hemostasis was obtained by vessel ligation and electrocoagulation. The wound was either left open (OP) or viable omentum sutured to its base (OM). Simulated bile leakage was noted in all of eight animals (four OM, four OP) studied on day of injury. None of 18 OM and two of 17 OP animals demonstrated extravasation of dye from the wound on the second and third postinjury day (N.S.). The ratio of mRNA for alpha 1(I) procollagen/actin, used as an indicator of wound healing, was 56.3 +/- 7.8 for OM and 50.6 +/- 12.1 for OP at the wound edge, and 63.5 +/- 18.6 and 69.2 +/- 7.5, respectively, for RNA isolated from the scar (N.S.). For alpha 1(III) procollagen mRNA, the ratio was 23.9 +/- 3.5 for OM and 22.4 +/- 8.3 for OP at the wound edge, and 32.4 +/- 6.5 and 31.8 +/- 7.9, respectively, for RNA isolated from the scar (N.S.). There was no difference in the scar hydroxyproline content between the two repair methods. In this model of hepatic injury and repair, bile leakage was minimal by the second postinjury day with both repair methods. Placing the omentum in liver lacerations did not contribute to accelerated wound healing as measured by simulated bile leakage and collagen biosynthesis.

Animals↗

A simplified approach to techniques of splenic salvage.

Splenic salvage or partial splenectomy may be simplified by following these basic steps. The spleen is completely mobilized from all of its attachments so that it is tethered only by its blood supply. Appropriate hilar and short gastric vessels are ligated, and devitalized splenic tissue is débrided. Parenchymal bleeding is controlled by compression using horizontal mattress sutures placed through pledgets of folded sheets of oxidized cellulose.

Humans↗

Prevention of vascular prosthetic infection with an antibiotic-bonded Dacron graft.

Surfactant-mediated antibiotic bonding was used in an animal model of aortic prosthetic infection. Control grafts, control plus parenteral oxacillin, and oxacillin-bonded Dacron grafts were challenged by local inoculation with Staphylococcus aureus. Ninety percent of controls, 80% of parenteral antibiotic recipients, and only 30% of antibiotic-bonded Dacron grafts became infected (p less than 0.01, p less than 0.03). Antibiotic-bonded grafts were also superior in terms of suture line cultures and patency. In separate experiments in a subcutaneous pouch model, antibiotic bonding significantly improved the median infective dose of Dacron over that of controls and Dacron soaked in cephalosporin. These studies demonstrate that antibiotic-bonded Dacron implants are highly resistant to infection. A multicenter clinical trial is planned.

Animals↗

Increased procollagen mRNA levels in carbon tetrachloride-induced liver fibrosis in rats.

Carbon tetrachloride-induced liver damage is a well-characterized experimental model for studying liver fibrosis. We used this model to examine alpha 1(I), alpha 1(III), and alpha 1(IV) procollagen mRNA levels during the development of liver fibrosis. Rats were given 0.5 ml of carbon tetrachloride/kg of body weight for 1-6 weeks. The liver tissue was assayed for collagen content by measuring total hydroxyproline content. Specific increases in procollagen mRNAs were assayed by slot blot hybridization. There was a significant increase in hydroxyproline content of liver tissue following 3 weeks of carbon tetrachloride treatment. The increase in tissue collagen content correlated with an increase in alpha 1(I) procollagen mRNA levels. At 5 and 6 weeks of treatment, there was an increase in alpha 1(III) procollagen mRNA levels. alpha 1(IV) procollagen levels increased slightly with five injections of carbon tetrachloride treatment. These results suggest that specific increases in procollagen mRNAs in liver fibrosis parallel, but do not precede, increases in tissue collagen content.

Animals↗

Infection-resistant continuous peritoneal dialysis catheters.

The techniques of bonding of anionic antibiotics by treatment with cationic surfactants were applied to continuous ambulatory peritoneal dialysis (CAPD) catheters. The elution of 14C-penicillin from tridodecylmethylammonium chloride (TDMAC) treated silicone elastomer catheters in dialysis solution was biphasic, with 95% dissociated from the catheter by 48 h. Forty percent of the TDMAC left the catheter surface during the initial 2 days. The ability of the surfactant TDMAC to bind antibiotics after incubation in dialysis solution correlated directly with the amount of surfactant remaining. Rats with intraperitoneal dialysis catheters were inoculated with exit site and intraluminal bacterial challenges. Intraperitoneal catheter tips treated with TDMAC-penicillin were rendered more resistant to colonization after exit site and intraluminal bacterial challenges.

Animals↗

The influence of debt, moonlighting, practice, oversupply and gender on career development of residents in university and independent training programs.

A survey of chief residents in general surgery was conducted to evaluate debt and moonlighting, planned practice characteristics, the influence of oversupply and gender. Debt and moonlighting were closely related. The latter also correlated statistically with the perceived oversupply of general surgeons. Most residents planned to practice in a suburban area, in a community or university affiliated hospital with some teaching responsibilities. General surgeons were those more likely to choose a rural area, a community hospital and no teaching responsibilities. Subspecialists were those more likely to choose an urban area, a university hospital and a complete teaching environment. Two-thirds of residents thought there was an oversupply of general surgeons. They were more likely to take fellowships, especially those in transplantation, vascular, trauma, oncologic and colorectal surgery. Women represented less than 10 per cent of chief residents. They differed from men in the types of fellowships chosen, moonlighting activity and interest in teaching.

Adult↗

Biliary enteric bypass for malignant obstruction.

A retrospective review was conducted on patients with malignant biliary obstruction and their management by either percutaneous transhepatic biliary drainage (PTHD) (16 patients) or by biliary enteric bypass (BEB) (17 patients). Patients were similar in respect to clinical staging. There was a significantly greater time of palliation (time out of the hospital) for the group treated by BEB and also a significant reduction in death from sepsis, although there was no difference in ultimate survival. Patients whose obstruction was unrelieved by PTHD were successfully treated by BEB. The type of initial management (PTHD or BEB) was apparently a function to which service the patient was originally admitted. Fourteen of 16 PTHD patients were originally admitted to the medical service, while 15/17 BEB treated patients were originally admitted to the surgical service. It appeared from this review that septic deaths and time out of the hospital could be better provided by BEB compared to PTHD.

Bile Duct Neoplasms↗