Biomedical subjects

R G Bennett

Publications and source records attributed to R G Bennett.

At least 55 records · Page 3Linked to original sources

PubMed1994

A direct inhibitory effect of insulin on a cytosolic proteolytic complex containing insulin-degrading enzyme and multicatalytic proteinase.

The insulin-degrading enzyme (IDE) and the multicatalytic proteinase (MCP) can be isolated as components of a cytosolic proteolytic complex. IDE is the primary enzyme involved in cellular degradation of insulin, and insulin has been shown to interact with cytosolic IDE. MCP is believed to be important in non-ubiquitin pathways of cellular protein degradation. Insulin has a dose- and time-dependent inhibitory effect on MCP degradation of N-succinyl-Leu-Leu-Val-Tyr 7-amino-4-methylcoumarin (LLVY), a substrate for MCP. Proinsulin also inhibits LLVY degradation in a dose-dependent manner. The effect of insulin is immediate as measured in a continuously monitored assay of LLVY degradation. Purification of the IDE-MCP complex using a variety of approaches, including affinity and conventional chromatography, retains the insulin effect on LLVY degradation as long as the complex remains intact. After ion-exchange chromatography, which separates IDE and MCP, insulin no longer has an inhibitory effect. Recombination of purified IDE and MCP does not restore the effect of insulin, but inclusion of additional components from the ion-exchange column does. These results support the existence of a functional cytosolic complex that contains IDE and MCP. Insulin interacts with IDE and alters the activity of MCP, suggesting a functional relationship between these two components and a mechanism for an intracellular action of insulin.

Amino Acid Sequence↗

PubMed1994

Identification and isolation of a cytosolic proteolytic complex containing insulin degrading enzyme and the multicatalytic proteinase.

The insulin degrading enzyme (IDE) is the first recognized member of a new class of metalloproteinases. Studies on the purification and the properties of this enzyme have led to divergent results and conclusions from different laboratories. The present manuscript suggests that many of the divergent results may be due to the interaction of this enzyme with other proteins as part of a proteolytic complex. IDE co-isolates with the multicatalytic proteinase (MCP) during a wide variety of purification approaches including affinity chromatography and conventional purification approaches. Ion exchange chromatography will partially or completely separate IDE and MCP. The SDS-PAGE protein bands at various purification steps suggest the presence of a cytosolic proteolytic complex containing IDE, MCP and other unidentified components and raise the possibility of a functional interaction among these proteins.

Amino Acid Sequence↗

PubMed1994

Double Z-plasty to enhance rhombic flap mobility.

BACKGROUND: Occasionally after a rhombic flap has been designed, cut, and undermined, it fails to transpose into the recipient wound as easily as had been anticipated. This problem may have occurred because of unexpected skin tension due to previous surgery near the operative site or improper orientation of the rhombic flap. OBJECTIVE: The purpose of this work is to show how unexpected restriction in rhombic flap movement can be overcome by using a double Z-plasty to increase tissue length. METHODS: A double Z-plasty was incorporated into the rhombic flap design in one patient. The biomechanics of the flap were analyzed, and the modified flap was used in three other patients. RESULTS: The addition of a double Z-plasty increased the movement of the rhombic flap in a predictable fashion in four patients. CONCLUSION: A double Z-plasty is useful to enhance rhombic flap mobility in certain uncommon situations.

Biomechanical Phenomena↗

PubMed1994

Urinary incontinence: a program that works.

Using a simple and inexpensive intervention, improvement in dryness was apparent by the first week of the study. More importantly, results were achieved by changing staff behavior, rather than residents' behavior.

Aged↗

PubMed1993

Occurrence of basal cell carcinoma among multiple trichoepitheliomas.

We describe four patients who developed basal cell carcinoma (BCC) among multiple facial trichoepitheliomas. The only clinical feature that distinguished the carcinomas from the trichoepitheliomas was their larger size in three of the four patients. None of the lesions ulcerated. Whether the BCCs developed independently or by transformation from a trichoepithelioma is uncertain. Mohs micrographic surgery was helpful in revealing the transition from one tumor type to the other so that as much normal tissue as possible could be saved. The literature on the relationship between multiple hereditary trichoepitheliomas and BCCs is reviewed.

Basal Cell Carcinoma↗

PubMed1993

High prevalence of skin cancer in World War II servicemen stationed in the Pacific theater.

BACKGROUND: A large proportion of our World War II patients with skin cancer had been stationed in the Pacific. OBJECTIVE: Our purpose was to determine whether a statistically greater number of World War II servicemen with skin cancer were stationed in the Pacific than the number stationed in Europe. METHODS: In a consecutive survey of 370 World War II servicemen with skin cancer who were stationed abroad, place of service, skin cancer types, skin type, ethnic background, and estimated average hours outdoors per day during their lifetime were determined. The number of veterans stationed in the Pacific and the number stationed in Europe with respect to these data were analyzed with the chi-square test. RESULTS: A statistically significantly greater number of Pacific veterans than Europe veterans had basal cell or squamous cell carcinomas. CONCLUSION: A few months to a few years of prolonged sun exposure in a high-sun-intensity area may result in skin cancer development many years after exposure.

Aged↗

PubMed1993

A history of tissue expansion. Concepts, controversies, and complications.

BACKGROUND: Tissue expansion has become a widely used adjunct in reconstruction of the skin. OBJECTIVE: To trace the history of the concept of tissue expansion from the ancient to the latest medical literature. METHODS: We reviewed the technologic developments in the materials and methods of tissue expansion. RESULTS: Tissue expansion is of clinical importance and can be understood by the biochemical, biomechanical, and histologic features of expanded skin. CONCLUSION: Tissue expansion is becoming widely used and accepted and its continued use under many circumstances is justified by the experimental and clinical results.

Animals↗

PubMed1993

Diarrhea among residents of long-term care facilities.

Diarrhea is a common problem among residents of long-term care facilities. Although the etiology of many cases of diarrhea will be noninfectious, the approach to managing all patients with diarrhea must include assuring the adequacy of hydration and controlling the spread of infection. The latter issue is especially critical in nursing homes where a large proportion of patients can became ill over a several-day period during an outbreak. Although most outbreaks of diarrhea are viral in origin, bacterial outbreaks can lead to hospitalization and even death. Increasing awareness among physicians and infection control practitioners of the correct approaches to investigating and managing cases of diarrhea among nursing home patients is necessary because the magnitude of this problem will grow as the number of individuals being cared for in long-term care facilities increases.

Aged↗

PubMed1993

Approach to acute diarrhea in the elderly.

Diarrhea is a common problem among the elderly that can have catastrophic results. Atherosclerosis predisposes older adults to morbid sequelae from dehydration resulting from diarrhea. Deaths related to diarrheal illnesses are recognized among older adults living in the community as well as among those confined to nursing homes. Outbreaks have most often been associated with excess deaths from diarrhea among nursing-home patients. Although most cases of dehydration from diarrhea result from gastrointestinal infections, noninfectious causes of diarrhea related to prescription of laxatives, side effects of medications, and use of enteral feedings are common. Clostridium difficile infection is particularly common among older adults in hospitals and nursing homes, and relapsing disease in these groups may be more frequent than among younger adults. The approach to an elderly patient with diarrhea is to ensure proper hydration using available oral rehydration solutions, proceed with diagnostic tests likely to yield a positive result, avoid the use of harmful antiperistaltic drugs, and provide adequate follow-up of the nutritional state.

Acute Disease↗

PubMed1992

Mohs micrographic surgery of the nail unit.

Malignancies of the nail unit are relatively uncommon, with squamous cell carcinoma (SCC) representing most of the reported cases. Squamous cell carcinoma of the nail unit, although commonly considered to be a curable malignancy, can and does kill. Review of the literature as well as a personal series confirm that Mohs micrographic surgery is an ideal treatment for periungual and subungual SCCs without osseous involvement. In addition, the anatomy and histology of nail unit SCC, as well as prognostic factors and perioperative evaluation as they relate to performing Mohs micrographic surgery, are reviewed.

Carcinoma↗

PubMed1992

Methicillin-resistant Staphylococcus aureus colonization in a long-term-care facility.

OBJECTIVE: To study the prevalence and risk factors for colonization with MRSA at a long-term-care facility. DESIGN: Cross-sectional surveillance culture survey. SETTING: A 233-bed university-affiliated long-term-care facility. MEASUREMENTS: Surveillance cultures for MRSA were performed on patients of two adjacent nursing units and on new admissions to the entire facility over a 4-month period. RESULTS: On the chronic medical unit, where patients known to be colonized had been cohorted, 20 of 38 (52.6%) were colonized vs 3 of 67 (4.5%) on the skilled/intermediate unit (P less than 0.001), suggesting that little intra-facility spread of MRSA occurs. Twenty-four of 55 (43.6%) chronic medical admissions were colonized vs 6 of 63 (9.5%) admitted to the other units (P less than 0.001). Thirteen of 30 (43.3%) admissions were not previously known to be colonized. By univariate analysis, colonized admissions were younger and more often male; had more listed diagnoses, including pressure sores, a previous positive MRSA culture, and urinary incontinence; were more often fed by feeding tube; and had longer durations of hospital stay prior to admission. Logistic regression analysis showed that the most powerful independent predictors of colonization at admission were: a prior positive culture for MRSA (OR 8.8, 95% CI 2.4, 32.4), male sex (OR 8.2, 95% CI 2.3, 29.7), urinary incontinence (OR 3.8, 95% CI 1.4, 10.4), and presence of pressure sores (OR 2.9, 95% CI 0.9, 9.2). CONCLUSIONS: Unrecognized colonization of nursing home residents with MRSA is common, and nursing homes are unwittingly repositories for patients colonized with MRSA following acute hospitalization. Gloving and careful attention to handwashing may limit spread of MRSA within nursing homes, and identification of colonized patients may be facilitated by targeted surveillance cultures of the most debilitated patients at admission.

Aged↗

PubMed1992

Colonisation with digoxin-reducing strains of Eubacterium lentum and Clostridium difficile infection in nursing home patients.

Stool specimens obtained from 77 residents of a nursing home were analysed to determine the relationship between colonisation with digoxin-reducing strains of Eubacterium lentum and infection with Clostridium difficile. Patients were categorised according to previous antibiotic treatment, prescription of enteral feedings, and pattern of bowel habits. Colonisation with digoxin-reducing E. lentum was less common in subjects infected with C. difficile, in those treated with antibiotics previously, and in those prescribed enteral feedings. Normal bowel habits were more common in those without C. difficile. The lowest incidence of diarrhoea was seen in patients without C. difficile who were colonised with digoxin-reducing species. This study establishes an inverse relationship between the presence of C. difficile and E. lentum that reduce digoxin which is related to previous treatment with antibiotics and prescription of enteral feedings. Bacterial markers may prove to be a useful tool for predicting clinical disturbances in bowel function.

Adult↗

PubMed1991

Identification of the metal associated with the insulin degrading enzyme.

Insulin degrading enzyme (IDE) is a thiol-dependent metalloendoprotease that is responsible for initiation of cellular insulin degradation. However, its exact mode of action and the factors controlling it are poorly understood. Since IDE is a metal requiring enzyme, we have examined which metal(s) is(are) endogenously associated with it. Using neutron activation analysis, we studied the metal content of a partially purified enzyme from three different tissues: rat skeletal muscle, rat liver, and human placenta. Our results indicate that zinc and manganese are associated with the enzyme with approximately 10 times more zinc as manganese being present. These results suggest that one or both of these two metals are endogenously associated with this enzyme and are a means of controlling the enzyme's activity.

Amino Acid Sequence↗

PubMed1991

Local skin flaps on the cheeks.

Local skin flap repairs on the cheek are discussed. Anatomic and special considerations are reviewed. Advancement, rotation, and transposition flaps are described.

Cheek↗

PubMed1991

Postoperative elevation of eyeglasses from the nasal bridge.

After surgery on the proximal nose, wearing eyeglasses can be difficult and uncomfortable. In addition, pressure on the skin underneath the eyeglass nose pads may modify wound healing. We describe simple techniques using readily available materials and optical devices that either reduce or remove pressure on the nose from eyeglasses.

Eyeglasses↗

PubMed1991

A technique to accurately construct a contact dressing.

We describe a technique to rapidly and accurately construct the contact layer of a composite dressing. This technique is simple to perform and is suitable for any open wound. It is especially useful for moderately sized wounds created during extirpation of tumors by Mohs micrographic surgery.

Bandages↗

PubMed1991

The effect of training on visual alignment discrimination and grating resolution.

The effect of training on an observer's ability to detect the misalignment of three points, a hyperacuity, and to resolve a six-line grating was studied in a transfer-of-training design with observers (4 in each of two experiments) who were experienced in making psychophysical judgments of other visual stimuli. The transfer-of-training design enabled us to look for any training-based improvement. Long periods of training produced no statistically significant improvement in performance under any condition. There were small practice-based improvements, but the primary patterns indicated threshold fluctuation rather than improvement. We interpret the results to indicate that the neural mechanisms underlying three-point alignment and grating discrimination, like those for gap bisection (Klein & Levi, 1985), are not malleable to any significant extent.

Attention↗

PubMed1991

Current concepts in Mohs micrographic surgery.

The evolution of fresh-tissue Mohs micrographic surgery is presented in this article. Special emphasis is given to accepted indications for Mohs micrographic surgery. Reconstructive techniques and certification in Mohs micrographic surgery are discussed.

Basal Cell Carcinoma↗