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Biomedical subjects

R C Merrell

Publications and source records attributed to R C Merrell.

At least 37 records · Page 2Linked to original sources
PubMed1998

The Spacebridge to Russia Project: internet-based telemedicine.

The National Aeronautics and Space Administration (NASA) has been a pioneer in telemedicine since the beginning of the human spaceflight program in the early 1960s. With the rapid evolution in computer technology and equally rapid development of computer networks, NASA and the Department of Surgery in Yale University's School of Medicine created a telemedicine testbed with the Russia Space Agency, the Spacebridge to Russia Project, using multimedia computers connected via the Internet. Clinical consultations were evaluated in a store-and-forward mode using a variety of electronic media, packaged as digital files, and transmitted using Internet and World Wide Web tools. These systems allow real-time Internet video teleconferencing between remotely located users over computer systems. This report describes the project and the evaluation methods utilized for monitoring effectiveness of the communications. The Spacebridge to Russia Project is a testbed for Internet-based telemedicine. The Internet and current computer technologies (hardware and software) make telemedicine readily accessible and affordable for most health care providers. Internet-based telemedicine is a communication tool that should become integral to global health care.

Computer Systems↗
PubMed1998

Total parenteral nutrition: techniques, complications, and prevention.

During the past half century, surgeons have demonstrated the greatest interest and have made the most concerted effort in developing innovative, comprehensive, and effective methods for providing adequate nutritional support to patients in the widest range of clinical conditions and situations. Several factors account for the continual stimulation of thoughtful surgeons and physicians to maintain or improve the nutritional status of their patients.

Journal Article↗
PubMed1995

Localization studies in patients with hyperparathyroidism.

Patients with hyperparathyroidism who have not had previous neck surgery do not require preoperative localization because of the high success rate of cervical exploration (95%) and the limited sensitivity and specificity of all imaging modalities currently in use. Successful parathyroid exploration requires knowledge of the normal and frequently encountered variations in parathyroid anatomy (Fig. 4). Experience permits recognition of often subtle multiple gland disease. In skilled surgical hands, results are excellent with minimal morbidity. When recurrent or persistent disease or previously operated patients are encountered, confirmation of the diagnosis and attempts at localization should precede operation. Technetium sestamibi SPECT imaging and ultrasonography with FNA of suspicious glands are complementary tests that are readily available, inexpensive, and well tolerated by patients. If these tests are unsuccessful, MRI, CT, and invasive procedures should be pursued until the gland is localized.

Biopsy, Needle↗
PubMed1995

Telemedicine: delivering medical expertise across the state and around the world.

Many aspects of medical care can now be delivered at a distance using telemedicine technology. Rapid video and computer-based communication of medical information makes it possible for a physician to "examine" a patient located in another city, to view highly detailed medical images, to consult with distant subspecialists, or to supervise complex medical procedures. This same technology can bring scattered health-care workers together for joint teaching conferences. The Yale Telemedicine Center has initiated a number of such programs ranging from providing consultations in real time to physicians in Saudi Arabia, to interpreting medical images across town or across the state. Telemedicine will become a powerful tool for managed health-care organizations which are responsible for the medical needs of widely distributed patients in a vertically integrated health-care delivery system. This paper reviews the evolution of telemedicine, its technical fundamentals, specific medical applications, and the activities of the Yale Telemedicine Center. Evolving uses for telemedicine in Connecticut are described.

Connecticut↗
PubMed1995

The abdomen as source of sepsis in critically ill patients.

Among patients with life-threatening sepsis that has no clear site of origin, the abdomen continues to be a probable and tractable possibility. The cavity has the microbiologic and anatomic potential for sudden or indolent sepsis and the cause may be either obvious or obscure. The abdomen or the various structures may be primary sources that are secondary and independent of disease that brought the patient to peril. They also could be secondary and dependent upon an abdominal operation complicated by sepsis. The partnership of intensivist and surgical consultant, addressing possibilities and challenges, must identify the most probable cause and the most timely response for positive intervention in the critically ill patient threatened by sepsis.

Abdomen, Acute↗
PubMed1993

Nonfunctioning islet cell carcinoma of the pancreas.

BACKGROUND: Nonfunctioning islet cell carcinoma of the pancreas has a variable and often indolent natural history, which has resulted in a wide range of treatment recommendations. To more clearly define the natural history and appropriate treatment of this disease, we reviewed our institutional experience over the last 39 years. METHODS: The records of all patients confirmed to have a nonfunctioning islet cell carcinoma of the pancreas were retrospectively reviewed. Kaplan-Meier life tables were constructed and log-rank comparisons were performed. RESULTS: The 73 patients studied had an overall 5-year actuarial survival rate of 50%. Patients with localized disease at presentation (n = 39) had a significantly higher survival rate (p = 0.03) compared with patients with metastatic disease (n = 34). The 19 patients who underwent a potentially curative resection of the primary tumor had a significantly higher survival rate (p = 0.03) compared with the 20 patients with locally advanced, unresectable, nonmetastatic disease. Nine of these 20 patients died of complications of the primary tumor. In contrast, only 2 of 22 cancer-related deaths in the 34 patients with metastatic disease at diagnosis were due to the primary tumor. CONCLUSIONS: (1) Surgical resection should be performed in patients with resectable nonmetastatic disease. (2) Resection of the primary tumor in the presence of metastatic disease is rarely indicated. (3) Innovative treatment strategies are needed for patients with locally advanced, unresectable, nonmetastatic tumors of the pancreatic head.

Adolescent↗
PubMed1992

Continuing evolution in the approach to severe liver trauma.

Surgical and radiologic techniques from computed tomography (CT) scanning and embolization to temporary gauze packing and mesh hepatorrhaphy have been developed to make the management of severe liver injuries more effective. Surgical approaches for severe liver trauma have been oriented to two major consequences of these injuries: hemorrhage and infection. Early attempts at hemorrhagic control found benefit only in temporary intrahepatic gauze packing. The subsequent recognition of complications after liver injury blamed the practice of packing, which then remained unused for more than 30 years. Yet more aggressive attempts at controlling hemorrhage without temporary packing failed to improve results. Temporary perihepatic gauze packing therefore has been reintroduced, but this is probably an imperfect solution. Mesh hepatorrhaphy may control bleeding without many of the adverse effects of packing. Fourteen patients are reported with severe liver injuries who have undergone mesh hepatorrhaphy, bringing the current reported experience with mesh hepatorrhaphy to 24, with a combined mortality rate of 37.5%. Thus far, it appears that only juxtacaval injuries fail to have their hemorrhage controlled with mesh hepatorrhaphy, but many believe that these injuries may be controlled by perihepatic packing. Prophylactic drainage of severe liver injuries is a concept for which there is little evidence of benefit. Furthermore, recent radiologic developments appear capable of draining those collections that do occasionally develop in the postoperative period. The ultimate challenge of liver transplantation for trauma has been attempted, but the experience is thus far very limited.

Abdominal Injuries↗
PubMed1990

Aldosterone-producing tumors (Conn's syndrome).

Adenomas of the adrenal cortex which produce aldosterone (APA) are among the surgically correctible causes of hypertension accounting for 0.5 to 1.0% of all hypertensive etiologies. The adenomas have a 5:1 predilection for women and generally present with hypertension or profound hypokalemia. A low plasma renin activity completes the triad for primary hyperaldosteronism which could be caused by adrenocortical cancer, a neoplasm with an average diameter of 12 cm, or idiopathic hyperaldosteronism (IHA), a bilateral hyperplasia of the zona glomerulosa of the adrenal cortex which responds poorly to surgical resection. The adenomas are small (2 cm) but can be localized by imaging or selective venous sampling. Resection has a high success rate with minimal morbidity.

Adenoma↗
PubMed1990

Update on pancreatic islet cell transplantation.

The biological validation of islet grafts would free total pancreas resection from the onus of severe diabetes mellitus. Islet cell transplants can reverse diabetes mellitus and prevent complications in animal models. Immune rejection has foiled attempts at human transplantation despite moderate success with whole pancreas grafts. Aggressive rejection of islet grafts has been extensively studied in animal models and seems no different in substance from standard cell-mediated rejection but vastly different in tenacity. Rejection cannot be prevented by immunosuppression strategies effective for transplantation of heart, kidney, or liver. New strategies to circumvent islet rejection include encapsulation of the islets to obfuscate immune recognition, pretreatment of the islets in vitro to reduce immunogenicity, donor manipulation to provide specific tolerance, and combination strategies. In the development of these strategies, much has been learned or confirmed about the nature of immune rejection, and another round of human trials can be anticipated.

Animals↗
PubMed1990

The effect of diabetes mellitus on aortic prostanoid synthesis and serum cholesterol levels in the rat fed a high cholesterol diet.

The effect of diabetes mellitus on serum cholesterol and aortic microsomal prostanoid synthesis was studied in cholesterol fed male Lewis rats. Normal, diabetic and diabetic rats treated with pancreatic islets were divided into three diet subgroups, control diet, control +2% cholesterol for 8 weeks and control +2% cholesterol diet for 16 weeks. Serum glucose levels were elevated three-fold in the diabetic group compared to normal. Treatment with islets restored serum glucose to normal levels in diabetic rats. The 2% cholesterol diet did not significantly alter serum glucose levels in any of the groups. Body weights in the diabetic group were significantly lower than normal or diabetic rats treated with islets. Feeding 2% cholesterol for 16 weeks significantly increased weight in normal and islet treated diabetic rats but not in the diabetic group. Aortic microsomal prostanoid synthesis was similar in all experimental groups with 6-keto-PGF1 alpha (PGI2 metabolite) being the major product synthesized in all groups. Aortic microsomal prostanoid levels were not altered by the 2% cholesterol diet. Serum cholesterol levels increased 14-fold in the diabetic group which returned to the normal level in the diabetic animals treated with islets. These data show that diabetes does not alter aortic microsomal prostanoid levels in the rat. However, diabetes significantly increased serum cholesterol levels which were reversed by islet transplantation.

Analysis of Variance↗
PubMed1989

Gallbladder response to enteral lipids in injured patients.

Severely injured patients are at risk for complications of gallbladder stasis in a spectrum from sludge formation and cystic duct occlusion by inspissation and, subsequently, acalculous cholecystitis. In a double-blind randomized trial, the effect of enteral lipids on the ability of the gallbladder to clear itself was tested. The gallbladder was assessed by ultrasonography for acute contractions, sludge and dilatation on days 1, 3, and 7 after injury. There were no significant differences between patients who received enteral lipids and controls. Both groups showed modest enlargement of the gallbladder and failure of contraction. In a population at risk for biliary stasis following severe trauma, standard enteral lipids did not elicit, acutely or chronically, an appropriate reflexive evacuation of the gallbladder.

Adult↗
PubMed1988

Beta cell contact and insulin release.

Insulin secretion by intact islets, dispersed islet cells and dispersed cells allowed to reaggregate was compared in perifusion. Although single cells and aggregates showed basal insulin secretion and a prompt response to glucose challenge, basal secretion, peak insulin secretion and total insulin secretion during a 60 minute stimulation were profoundly less than those activities of intact islets. These results suggest that dispersed beta cells are responsive to glucose as a secretagogue, but the magnitude of the response is greatly diminished and not restored by simple cell contact.

Animals↗
PubMed1988

Cyclosporin A and islet function.

Long-term cyclosporin A (CsA) administration in dogs was studied with respect to function of the islets of Langerhans. After 3 weeks of immunosuppression with therapeutic doses, the islets were isolated and assessed in vitro for insulin release in response to glucose challenge. Islet tissue retrieved from the CsA-treated animals showed a total insulin output significantly lower than that of the control animals (p less than 0.01). The first and second phases of insulin release were both impaired in animals treated with CsA compared with controls (p less than 0.001 and p less than 0.05, respectively). The negative impact of CsA on the beta cells was easily demonstrated in this in vitro study. Similar results are more difficult to achieve with purely in vivo models, probably due to the great redundancy of the islet mass in intact animals. The mechanism of this CsA toxicity remains to be defined.

Animals↗