PubMed Health⌕ Search

Biomedical subjects

R Sellers

Publications and source records attributed to R Sellers.

10 recordsLinked to original sources
PubMed2001

Improved flow cytometric detection of HLA alloantibodies using pronase: potential implications in renal transplantation.

BACKGROUND: Flow cytomeric crossmatch (FCXM) has grown in popularity and has become the "standard of practice" in many programs. Although FCXM is the most sensitive method for detecting alloantibody, the B cell FCXM has been problematic. Difficulties with the B cell FCXMs have been centered around high nonspecific fluorescence background owing to Fc-receptors present on the B cells and autoantibodies. To improve the specificity and sensitivity of the B cell FCXM, we utilized the proteolytic enzyme pronase to remove Fc receptors from lymphocytes before their use in FCXM. METHODS: Lymphocytes isolated from peripheral blood, spleen, or lymph nodes were treated with pronase and then used in a three-color FCXM. A total of 167 T- and B cell FCXMs using pronase-treated and untreated cells were performed. Testing used serial dilutions of HLA allosera (22 class I and 6 class II), with the titer of each antibody at one dilution past the titer at which the complement-mediated cytotoxicity anti-human globulin crossmatch became negative. RESULTS: After pronase treatment, the actual channel values of the negative control in both T cell and B cell FCXMs declined from 78+/-10 to 57+/-4 (P<0.05) and 107+/-11 to 49+/-3 (P<0.00001), respectively. Pronase treatment resulted in improved sensitivity of the T and B cell FCXM in detecting class I antibody by 20% and 80%, respectively. In no instance was a false-positive reaction observed. In this study, pronase treatment improved the specificity of B cell FCXM for detecting class II antibodies from 75% to 100% (P=0.03). In no instance was a false-negative reaction recorded. Lastly, on the basis of these observations we re-evaluated three primary transplant recipients who lost their allografts because of accelerated rejection. One of the patients was transplanted across negative T and B cell FCXM, whereas the other two patients were transplanted across a positive T cell, but negative B cell, FCXM. After pronase treatment, T and B cell FCXMs of each patient became strongly positive, and donor-specific anti-HLA class I antibody was identi. fied in each case. CONCLUSION: Utilization of pronase-treated lymphocytes improves both the sensitivity and specificity of the FCXM.

False Negative Reactions↗
PubMed2001

Perceived racism and self and system blame attribution: consequences for longevity.

In this article, we examine the National Survey of Black Americans to assess the relationship between perceived racism, self and system blaming attribution and survival. Perceived exposure to racism and other covariates were measured at baseline (1979) with a mortality follow up 13 years later (1992). We test the hypothesis that an external attributional orientation (which we refer to as system blaming) as opposed to an internal attributional orientation (which we refer to as self blaming) will be protective of health (as measured at 13-year survival) when individuals are exposed to racism. Using Cox proportional hazards regression modeling, we found support for our hypothesis. African Americans with a system-blaming orientation who reported experiencing racism were more likely to survive the 13-year follow-up period, compared to self blamers who did not perceive themselves to have been exposed to racism (OR = .37, CI95: .21, .64). Controlling for other known correlates of survival (age, health status at baseline, sex, marital status, smoking, and income) did not eliminate the significant effect of self-blame orientation among those exposed to racism (OR = .43, CI 95: .23, .82). The findings suggest that the attribution of negative events to external factors, such as systemic societal racism, rather than to individual characteristics, may be adaptive and protective of health status.

Adolescent↗
PubMed2000

Frequency, potential risk and therapeutic intervention in end-stage renal disease patients with antiphospholipid antibody syndrome: a multicenter study.

BACKGROUND: Antiphospholipid antibody syndrome (APAS) is characterized by the presence of anticardiolipin antibodies (ACA) in association with thrombotic disorders of arterial and/or venus systems, spontaneous abortion(s) or thrombocytopenia. METHODS: In this multicenter study, 502 end-stage renal disease (ESRD) patients awaiting renal transplants were screened to determine the frequency of APAS, the potential risk associated with APAS, and strategies for therapeutic intervention. Ninety-three patients (19%) had high titers of ACA. Twenty-three patients had documented evidence of one or more of the thrombotic disorders such as lupus, frequent abortions, frequent thrombosis of arteriovenous shunts, biopsy-proven microrenal angiopathy, or thrombocytopenia and thus were diagnosed with APAS. Of these 23 patients, 11 received kidney transplants either with (4 patients) or without (7 patients), concomitant anticoagulation therapy. RESULTS: All seven of the patients with APAS not treated with anticoagulation therapy lost their allografts within 1 week as a result of renal thrombosis. In contrast, three out of four transplant patients with APAS treated with anticoagulation therapy maintained their allografts for over 2 years. The fourth patient lost his graft within a week because of thrombosis. Of the remaining 70 patients with high titers of ACA but no evidence of thrombotic disorders, 37 received kidney transplants. None lost their allografts as a result of thrombosis. Our data suggest that, although 19% of our ESRD patients exhibit high titer of ACA, only 5% of the patients have APAS. CONCLUSION: In conclusion, our data suggest that the patients with APAS are at high risk of posttransplant renal thrombosis. Anticoagulation therapy could prevent patients from posttransplant thrombosis in patients with APAS.

Antibodies, Anticardiolipin↗
PubMed1997

Regulatory and legal aspects of supplementing grazing ruminants.

The current legal and regulatory status of classes of feed additives is discussed, including food additives permitted in animal feed and drinking water, generally recognized as safe (GRAS) ingredients, and approved animal drugs. A brief description of these feed additive classes is given. Some nutritional and practical considerations are given for feed additives, and some special considerations are provided for free-choice feeding, medicated liquid feeds, sodium molybdate, and chromium compounds.

Animal Husbandry↗
PubMed1995

Neodymium: yttrium-aluminum-garnet laser dosimetry for the prolase II side-firing delivery system in the human prostate.

OBJECTIVES: The objective of this study was to define optimal treatment parameters and quantitative dosimetry for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser coagulation prostatectomy utilizing the ProLase II side-firing laser delivery system. METHODS: Transurethral Nd:YAG laser application was performed with the ProLase II side-firing laser fiber in adult human prostates prior to planned radical prostatectomy. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 40 to 80 W, while holding total energy delivery constant. Holding the power setting constant, the extent of tissue coagulation was similarly measured for variable treatment times from 45 to 90 seconds. RESULTS: Peak tissue coagulation for the ProLase II was observed at 60 W--up to a maximum of 13 mm tissue penetration and 3.92 cc volume coagulation following a single spot laser application. The mean depth of tissue coagulation at 60 W power setting was 12.7 mm, with a mean volume of tissue coagulation of 3.07 cc. Holding the power setting constant at 60 W, and increasing treatment time from 45 to 60 seconds, the extent to tissue coagulation increased significantly. However, beyond 60 seconds continuous laser application at 60 W, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 60 and 90 seconds. CONCLUSIONS: Using the ProLase II side-firing laser fiber, 60-second Nd:YAG spot laser applications at 60 W power setting represent optimal treatment parameters. The quantitative dosimetry curves produced for the ProLase II fiber are compared with prior dosimetry studies with the Urolase delivery system.

Aged↗
PubMed1995

Insight into mechanism of neodymium: yttrium-aluminum-garnet laser prostatectomy utilizing the high-power contact-free beam technique.

OBJECTIVES: The objective of this study was to define the actual mechanism of neodymium: yttrium-aluminum-garnet (Nd:YAG) laser prostatectomy achieved with the previously described contact-free beam technique using the Ultraline delivery system at high-power settings. METHODS: Transurethral Nd:YAG laser application was performed with the Ultraline side-firing laser fiber in canine and human prostates. Total or radical prostatectomy was performed after laser treatment to examine and measure laser tissue effects produced using the contact-free beam technique. RESULTS: Minimal actual tissue evaporation or vaporization was noted in either the canine or human prostate using this technique. The extent of tissue vaporization achieved was probably insufficient to produce clinically significant voiding outcomes acutely or chronically. However, this technique, using the Nd:YAG laser, produced excellent tissue coagulation and necrosis, similar to other laser delivery systems and reports dealing with laser coagulation prostatectomy. CONCLUSIONS: The primary mechanism accounting for therapeutic efficacy of the contact-free beam technique for Nd:YAG laser prostatectomy utilizing the Ultraline delivery system at high-power settings appears to be tissue coagulation with subsequent necrosis and slough, rather than tissue vaporization. This is consistent with the known tissue effects of the Nd:YAG laser wavelength in other systems.

Animals↗
PubMed1987

Effects of posture on cardiac dynamics during visual search.

Cardiovascular psychophysiologists are employing emerging non-invasive technologies to chart the changes in a variety of parameters of cardiac activity as psychological tasks are performed. One technique, impedance cardiography, makes it possible to assess cardiac output and contractile force while psychological tasks are being performed. This study was designed to determine if facilitating the venous return of blood from the legs would alter the pattern of cardiac changes that have been noted in earlier impedance cardiographic studies of the effects of psychological challenge. Twenty normotensive males performed visual search in upright, sitting and reclining positions and impedance cardiographic assessments of cardiac output and stroke volume, and an index of contractility were obtained. In addition, heart rate and two systolic time intervals were measured. As expected, decreases in stroke volume occurred as heart rate increased during visual search. Hence cardiac output (heart rate X stroke volume) remained stable. Higher levels of cardiac output, stroke volume and contractility were recorded in the reclining versus the upright position. However, the patterns of cardiac activity did not differ before, during and after performance when body position was altered. Hence, posture altered the absolute levels of several cardiac parameters, but did not affect the configuration of cardiac changes associated with performing a mildly challenging task.

Adolescent↗
PubMedDate not supplied

Strength testing after third-degree acromioclavicular dislocations.

Twenty male patients with a grade III acromioclavicular joint dislocation were evaluated more than 2 years after their injury; the average followup was 4.5 years. Strength testing was performed with a Cybex II dynamometer in three planes evaluating flexion, extension, internal rotation, external rotation, abduction, and adduction at 60 and 120 deg/sec. Subjective complaints were minor and neither daily activities nor athletic participation were impaired. Objectively, only one patient had tenderness over the acromioclavicular joint. All patients had full motion and negative impingement signs. Strength testing with the Cybex II dynamometer showed no significant difference (P less than 0.05) between the injured and uninjured shoulder for strength in internal rotation, external rotation, abduction, adduction, extension, or flexion at speeds of 60 and 120 deg/sec. This study shows that the strength of the shoulder is not significantly affected by conservative treatment of grade III acromioclavicular dislocations. Conservative treatment results in minimal or no functional deficit. The authors recommend that grade III acromioclavicular dislocations be treated nonoperatively.

Acromioclavicular Joint↗