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Biomedical subjects

K Burke

Publications and source records attributed to K Burke.

At least 55 records · Page 3Linked to original sources
PubMed1994

The influence of combined kidney-pancreas transplantation on the progression of diabetic retinopathy. A case series.

PURPOSE: To evaluate the impact of combined kidney and pancreas transplantation on the progression of advanced diabetic retinopathy. METHODS: The changes in diabetic retinopathy severity in patients with insulin-dependent diabetes mellitus who had kidney-pancreas transplantation (n = 51) and in those who had kidney transplantation only (n = 21) were compared. Patients were invited to baseline and 1 year follow-up examinations. Fundus photographs were graded in a masked fashion using standardized protocols. RESULTS: The mean age and duration of diabetes were similar for both groups. After combined transplantation, none of the patients used insulin, and their mean glycosylated hemoglobin was significantly lower (6.4% versus 10.6%) than those who underwent only kidney transplantation. There was a nonsignificant difference in overall progression of retinopathy for combined transplantation compared with kidney transplantation only (risk ratio = 0.73; 95% confidence interval, 0.31, 1.71). CONCLUSION: The authors found no evidence that the normalization of glycemia associated with a combined kidney-pancreas transplantation in patients with advanced proliferative diabetic retinopathy (mostly treated with photocoagulation) accelerated retinopathy progression. These data suggest that the normalization of glycemia associated with a combined kidney-pancreas transplantation does not have beneficial influence on the progression of advanced diabetic retinopathy.

Adult↗
PubMed1994

Intraoperative duplex scanning and late carotid artery stenosis.

PURPOSE: The purpose of this study was to assess the effect of intraoperative duplex scanning on early and late results after carotid endarterectomy. METHODS: We reviewed 316 carotid arteries in 283 patients who underwent operation since 1986. The results of intraoperative ultrasonography were normal in 254 (80.4%) and abnormal in 62 (19.6%). We did not reexplore 53 (85.5%) of the abnormalities because the defect was minor, 2 to 3 mm or less. These defects were retained atheroma in the common carotid artery (n = 35), internal carotid artery (ICA) (n = 5), external carotid artery (n = 2), small frond in the bulb (n = 2), thickened wall of the vein patch (n = 2), and ICA kink (n = 7), two of which were associated with retained atheroma. Nine defects (14.5%) were reexplored and repaired; there were seven flaps, one residual plaque, and one case with turbulent flow alone. RESULTS: Patients with a normal examination result had an early ICA occlusion rate of 0.79% (n = 2), an early stroke rate of 1.6% (n = 4), and one death (0.4%). In the unrepaired group these rates were 1.9% (n = 1) and 1.9% (n = 1), respectively. No occlusion occurred in the repaired group, but one preexisting cerebrovascular accident worsened immediately after operation. Frequency analysis and B-mode imaging were performed after operation and every 6 to 12 months in all patients (mean 21.6 months). A greater than 75% area stenosis was found in nine (17%) of the 53 unrepaired carotid arteries, but in only four (4.3%) of the 254 carotid arteries lacking defects and in one of the reopened group (p < 0.001). There have been no late strokes, and only three late transient ischemic attacks overall. CONCLUSIONS: A normal intraoperative scanning result obtained after carotid endarterectomy is associated with improved late patency rates. Even small defects appear to be associated with an increased incidence of late restenosis, reemphasizing the importance of technical perfection.

Adult↗
PubMed1994

Perceptions of preschoolers' vulnerability by mothers who had delivered preterm.

Assessed mothers who did and did not identify their children as vulnerable on a number of variables including perception of their child's behavior problems and their own sense of parental control. Children were also examined to determine their developmental abilities. Participants included 50 preschoolers who were born prematurely, their mothers, and their medical care providers. The mothers' response to the Vulnerable Child Scale was used to identify children as vulnerable and nonvulnerable. Mothers who perceived their children as vulnerable also rated them on the Child Behavior Checklist 2/3 as having more somatic problems and as being more aggressive, destructive, and poorly socialized. Additionally, these mothers expressed a diminished sense of parental efficacy and less control of their child's behavior as measured by the Parental Locus of Control Scale. However, results from the McCarthy Scales of Children's Abilities and the medical care provider's questionnaire revealed no differences between the groups of children. Overall findings suggest preschoolers born prematurely whose mothers perceive them as vulnerable are at risk for the Vulnerable Child Syndrome described by Green and Solnit (1964).

Adult↗
PubMed1994

Critical care clinical nurse specialist in home health care: survey results.

Two surveys were designed and sent to health care providers in the Philadelphia metropolitan area. The purpose of the surveys was to explore whether there was a need for critical care CNSs (CCCNS) in the field of high-tech, complex home care and to determine the characteristics of that role. In addition, the surveys sought to identify the necessary curriculum content a CCCNS graduate program should include to prepare individuals for practice in home care. One survey was sent to home care providers and an amended version to in-hospital personnel identified as responsible for discharge planning. Eighty-three percent of the home care survey respondents and 85% of the in-hospital survey respondents perceived a need for a CCCNS in the high-tech, complex home care field. The identified roles of the CCCNS in home care were similar for both respondent groups. They included consultant to the home care agency, patient-family educator, staff educator, and hospital-to-home coordinator. Some suggestions for curriculum content included courses on technology, discharge planning, health policy, and chronic illness. Although a preliminary exploration, the surveys demonstrated the existence of patients with high-tech, complex home care needs and supported the belief that CCCNSs have a role in their care.

Continuity of Patient Care↗
PubMed1994

The accuracy of technetium-99m-labeled red cell scintigraphy in localizing gastrointestinal bleeding.

OBJECTIVE: To evaluate the success of technetium-99m-labeled red blood cell scintigraphy in localizing the site of gastrointestinal bleeding, and to identify the clinical and technical factors that contribute to scan accuracy. METHODS: A retrospective review was conducted of all patients who underwent a tagged red blood cell scan for the evaluation of gastrointestinal bleeding at our institution from 1981 to 1991. RESULTS: Of a total of 153 patients, 90 (59%) had positive scans, whereas, in 63 (41%), they were negative. Of the 90 patients who had positive scans, it was possible to assess scan accuracy in 44 who had corrective surgery or an additional diagnostic procedure which definitively localized the site of bleeding. Of those 44 patients, the correct bleeding site was identified by red blood cell scanning in 33 patients (75%) overall and in all six patients with a left colon bleeding site. In this group of 44 patients, 22 scans were positive within 2 h, and of these the scan was accurate in localizing the bleeding site in 19 of 22 (86%). When the three subjects with upper gastrointestinal bleeding were excluded, the scan was positive in 100% of the remaining 19 patients. CONCLUSION: The technetium-labeled red blood cell scan is a reliable tool for the assessment of unexplained lower gastrointestinal bleeding when the scan is positive within the first 2 h, and an upper gastrointestinal source has already been excluded.

Aged↗
PubMed1993

Alloreactive cytotoxic T lymphocytes generated in the presence of viral-derived peptides show exquisite peptide and MHC specificity.

The nature of alloreactivity to MHC molecules has been enigmatic, primarily because of the observation that allogeneic responses are considerably stronger than syngeneic responses. To better determine the specificity potential of allogeneic responses, we have generated alloreactive CTL specific for exogenous, viral-derived peptide ligands. This approach allowed us to critically evaluate both the peptide- and MHC-specificity of these alloreactive T cells. Exploiting the accessibility of the H-2Ld class I molecule for exogenous peptide ligands, alloreactive CTL were generated that are specific for either murine cytomegalovirus (MCMV) or lymphocytic choriomeningitis virus (LCMV) peptides bound by Ld alloantigens. Peptide specificity was initially observed in bulk cultures of alloreactive CTL only when tested on peptide-sensitized T2.Ld target cells that have defective presentation of endogenous peptides. Subsequent cloning of bulk alloreactive CTL lines generated to MCMV yielded CTL clones that had exquisitely specific MCMV peptide recognition requirement. All of the MCMV/Ld alloreactive CTL clones were also exquisitely MHC-specific in that none of the CTL clones lysed targets expressing MCMV/Lq complexes, even though Lq differs from Ld by only six amino acid residues and Lq also binds the MCMV peptide. This observation clearly demonstrates that alloreactive CTL are capable of the same degree of specificity for target cell recognition as are syngeneic CTL in MHC-restricted responses.

Amino Acid Sequence↗
PubMed1993

Effects of walnuts on serum lipid levels and blood pressure in normal men.

BACKGROUND: In a recent six-year follow-up study, we found that frequent consumption of nuts was associated with a reduced risk of ischemic heart disease. To explore possible explanations for this finding, we studied the effects of nut consumption on serum lipids and blood pressure. METHODS: We randomly placed 18 healthy men on two mixed natural diets, each diet to be followed for four weeks. Both diets conformed to the National Cholesterol Education Program Step 1 diet and contained identical foods and macronutrients, except that 20 percent of the calories of one diet (the walnut diet) were derived from walnuts (offset by lesser amounts of fatty foods, meat, and visible fat [oils, margarine, and butter]). RESULTS: With the reference diet, the mean (+/- SD) serum values for total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol were, respectively, 182 +/- 23, 112 +/- 16, and 47 +/- 11 mg per deciliter (4.71 +/- 0.59, 2.90 +/- 0.41, and 1.22 +/- 0.28 mmol per liter). With the walnut diet, the mean total cholesterol level was 22.4 mg per deciliter (0.58 mmol per liter) lower than the mean level with the reference diet (95 percent confidence interval, 28 to 17 mg per deciliter [0.72 to 0.44 mmol per liter]); the LDL and HDL cholesterol levels were, respectively, 18.2 mg per deciliter (0.47 mmol per liter) (P < 0.001) and 2.3 mg per deciliter (0.06 mmol per liter) (P = 0.01) lower. These lower values represented reductions of 12.4, 16.3, and 4.9 percent in the levels of total, LDL, and HDL cholesterol, respectively. The ratio of LDL cholesterol to HDL cholesterol was also lowered (P < 0.001) by the walnut diet. Mean blood-pressure values did not change during either dietary period. CONCLUSIONS: Incorporating moderate quantities of walnuts into the recommended cholesterol-lowering diet while maintaining the intake of total dietary fat and calories decreases serum levels of total cholesterol and favorably modifies the lipoprotein profile in normal men. The long-term effects of walnut consumption and the extension of this finding to other population groups deserve further study.

Adult↗
PubMed1993

Approaches to the construction of new candidate poliovirus type 3 vaccine strains.

The World Health Organization has called for improvements to oral polio vaccines (OPV), particularly the type 3 component. Our improved understanding of the genetic basis of attenuation and antigenicity of this strain gives rise to possibilities for constructing new derivatives via mutagenesis of infectious cDNA. This article reviews progress made with various approaches to constructing a new type 3 candidate vaccine strain. These include the construction of antigen chimaeras of poliovirus based on the Sabin type 1 strain, the introduction of new genetically stable attenuation mutations into the 5' non-coding region (NCR) of the type 3 poliovirus genome, and the introduction of mutations which may increase the thermostability of the type 3 vaccine.

Antibodies, Viral↗
PubMed1992

Mutations in the araC gene of Salmonella typhimurium LT2 which affect both activator and auto-regulatory functions of the AraC protein.

The araC gene encodes a regulatory protein, AraC, that acts as both an activator and a repressor of transcription of the genes involved in the transport and catabolism of L-arabinose in Salmonella typhimurium LT2. Five araC mutants which have altered regulatory properties were characterized. All are point mutations which would result in amino acid substitutions near the C terminus of AraC. Each mutation results in altered activator and auto-regulatory AraC function in vivo. In vitro DNA-binding assays showed that three mutant AraC have measurable lowered affinity for ara controlling site DNA. The data are consistent with a model in which there is a DNA-binding domain in the C terminus of AraC which functions in both activation and repression.

Alleles↗
PubMed1992

Immunogenicity and antigenicity of chimeric picornaviruses which express hepatitis A virus (HAV) peptide sequences: evidence for a neutralization domain near the amino terminus of VP1 of HAV.

We evaluated the antigenic characteristics of chimeric picornaviruses created by inserting peptide sequences from hepatitis A virus (HAV) capsid proteins into the B-C loop of VP1 of Sabin strain type 1 poliovirus (PV-1). Fifteen viable chimeras were generated. Each retained the ability to be neutralized by polyclonal PV-1 antisera. Two chimeras (H15 and H2) stimulated production of low levels of HAV neutralizing antibodies in immunized rabbits or mice, although in both cases only a small fraction of immunized animals produced this response. The H15 chimera, which contains residues 13-24 of HAV VP1, elicited HAV neutralizing antibodies in three of nine rabbits and at least one of seven immunized mice. These results indicate that a neutralization domain exists in this region of VP1. However, human sera with high titers of antibodies to HAV failed to neutralize or immunoprecipitate this chimera, suggesting the absence of a significant antibody response to this neutralization domain following natural infection. Sera from rabbits immunized with H15 that did not develop HAV neutralizing antibodies contained antibodies reactive with the HAV peptide segment expressed by the H15 virus, indicating substantial differences in the specificities of antibodies elicited by this peptide segment among individual immunized rabbits. The H15 peptide insert was an effective antigen, as indicated by a high level of sensitivity of the H15 chimera to neutralization by a related anti-peptide antibody which was itself devoid of HAV neutralizing activity. One of 16 rabbits immunized with the H2 chimera (residues 101-108 of HAV VP1) developed HAV neutralizing antibodies, confirming both the presence and the highly conformational nature of a neutralization antigenic site involving these residues of HAV.

Amino Acid Sequence↗