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Biomedical subjects

D L Dunn

Publications and source records attributed to D L Dunn.

At least 127 records · Page 7Linked to original sources
PubMed1993

A rapid procedure for purifying IgM monoclonal antibodies from murine ascites using a DEAE-disk.

A method for purifying IgM monoclonal antibodies (mAbs) from murine ascites using a DEAE-disk is described. After ammonium sulfate precipitation, ascites proteins are redissolved and loaded onto a DEAE-disk. MAb then is eluted from the disk using a stepwise NaCl gradient. IgM mAb produced by this procedure was > 95% pure as assessed by reducing SDS-PAGE analysis and was free of significant IgG contamination as determined by double radial immunodiffusion analysis. Yield of IgM mAb was approximately 2% of total ascites protein and approximately 10% of the amount of IgM contained in crude ascites. MAb retained immunoreactivity as assessed by ELISA, and the affinity index was evaluated by thiocyanate elution and remained unchanged. This two step technique for purifying IgM mAb from murine ascites is rapid, simple, and yields mAb of sufficient purity and immunoreactivity for the majority of mAb applications.

Animals↗
PubMed1993

Ganciclovir susceptibilities of cytomegalovirus (CMV) isolates from solid organ transplant recipients with CMV viremia after antiviral prophylaxis.

Ganciclovir susceptibility studies were done on the last cytomegalovirus (CMV) isolate available from 42 solid organ transplant recipients with CMV viremia who were enrolled in a prospective CMV prophylactic trial. Viruses were categorized as follows: 13 isolates (group 1) from patients who received ganciclovir prophylaxis; 9 isolates (group 2) from patients who received acyclovir prophylaxis; 8 isolates (group 3) from patients who received acyclovir prophylaxis and ganciclovir treatment; and 12 isolates (group 4) from patients who received prophylaxis and treatment with ganciclovir. All CMV isolates were sensitive to ganciclovir (mean 50% inhibitory concentration [IC50] 1.7 microM; range, 0.2-5.3 microM). Mean IC50 values (in microM) were 1.7 for group 1 isolates, 1.2 for group 2 isolates, 2.2 for group 3 isolates, and 1.7 for group 4 isolates (P > .05). Thus, acyclovir or ganciclovir prophylaxis in solid organ transplant patients did not select ganciclovir-resistant isolates of CMV.

Acyclovir↗
PubMed1993

Anti-endotoxin monoclonal antibodies inhibit secretion of tumor necrosis factor-alpha by two distinct mechanisms.

OBJECTIVE: To determine whether monoclonal antibodies (mAbs) directed against lipopolysaccharide (LPS, endotoxin) act by promoting LPS neutralization, LPS uptake by macrophages, or both processes, the authors assessed the effects of these agents on LPS-induced cytokine secretion and cellular uptake of LPS. SUMMARY BACKGROUND DATA: MAbs directed against LPS have been shown to attenuate LPS-induced macrophage tumor necrosis factor-alpha (TNF-alpha) secretion, a process that may contribute to protective capacity. The mechanisms by which this process occurs have not been established. METHODS: MAbs directed against LPS were evaluated in vitro for their capacity to (1) inhibit TNF-alpha secretion, and (2) alter fluorescein isothiocyanate-labeled LPS uptake (employing flow cytometry analysis and fluorescence microscopy) by the macrophage-like cell line RAW 264.7. RESULTS: MAb 8G9, an IgG3 directed against the O-antigen polysaccharide region of Escherichia coli 0111:B4 LPS, significantly reduced LPS-induced TNF-alpha secretion and promoted a more than 40-fold increase in LPS uptake by macrophages. The authors established that this was mediated by a Fc receptor-mediated process because 8G9 F(ab')2 fragments that lack the Fc portion of the IgG molecule were capable of inhibiting TNF-alpha secretion, but did not promote increased LPS uptake to the same degree. Cross-reactive, anti-deep core/lipid A mAb 1B6, an IgG2a, also promoted uptake of E. coli 0111:B4 LPS and O-antigen polysaccharide-deficient E. coli J5 LPS, but only inhibited TNF-alpha secretion induced by E. coli J5 LPS to which it binds most efficiently. MAb 3D10, an IgM also directed against the O-antigen polysaccharide region of E. coli 0111:B4 LPS, inhibited TNF-alpha secretion but did not increase cellular uptake of LPS, presumably acting solely due to LPS neutralization. Polymyxin B, an antibiotic that binds stoichiometrically to the lipid A portion of LPS, inhibited TNF-alpha secretion and prevented cellular LPS uptake. CONCLUSIONS: These results suggest that IgG and IgM anti-LPS mAbs exert protective capacity by extracellular neutralization of LPS, while IgG Fc receptor-mediated cellular uptake also may serve to bypass macrophage activation and TNF-alpha secretion by promoting internalization and intracellular neutralization.

Animals↗
PubMed1993

Environmental monitoring and dose assessment following the December 1991 K-reactor aqueous tritium release.

Between 22 December and 25 December 1991, approximately 570 L of tritiated water was released from the K Reactor at the Savannah River Site. Analyses of river flow rates and measured tritium concentrations showed that approximately 210 TBq of tritium had been released from the reactor and was being transported down the Savannah River. Elevated tritium concentrations in the Savannah River were first detected on 26 December 1991. The maximum measured tritium concentration at Highway 301 (a major sampling point 37 km downstream of the Savannah River Site) was 2.5 Bq mL-1. A hypothetical maximum individual located at Highway 301 would have received a drinking water dose of approximately 0.35 microSv, less than 1% of the Environmental Protection Agency's 40 microSv y-1 drinking water standard. Concentrations at the intake canals to two water treatment facilities, approximately 160 km downstream, began to rise above normal on 28 December. The population dose to users of the downstream domestic water supplies and consumers of Savannah River biota was estimated to be 4.7 x 10(-3) person-Sv.

Environmental Monitoring↗
PubMed1993

Risk factors for chronic rejection in renal allograft recipients.

Chronic rejection is a major barrier to long-term renal allograft survival. Cyclosporine, though effective at reducing graft loss to acute rejection, has had little impact on the incidence of chronic rejection. Between June 2, 1986 and January 22, 1991, 587 kidney-alone transplants (566 patients) were performed, and had been entered into our renal transplant database and had at least 1 year of follow-up: 103 with biopsy-proven chronic rejection (37 living-related donor, 66 cadaver) and 484 without chronic rejection (236 LRD 248 CAD). The 5-year patient survival was 84% for recipients with biopsy-proven chronic rejection vs. 89% without (P = .08). The 5-year graft survival was 31% for recipients with biopsy-proven chronic rejection vs. 81% without (P < .0001). Using multivariate analysis, we determined the impact on the incidence of chronic rejection of these variables: transplant number, age at transplant (< 18 years, 18 to 50 years, > 50 years), gender, human leukocyte antigen matching, peak and transplant panel-reactive antibody, acute rejection episodes, infections (including cytomegalovirus, viral, and bacterial), donor age, and CsA dosage at 1 year (< 5 mg/kg vs. > or = 5 mg/kg). Logistic regression models were fit to the data using a forward stepwise selection procedure. In this analysis, risk factors included an acute rejection episode (P < .001), CsA dosage < 5 mg/kg/day at 1 year (P = .007), infection (P = .023), female gender (P = .042), and retransplant (P = .103). Individual analyses were done for CAD and LRD recipients. For both groups, important variables were acute rejection, infection, CsA dosage at 1 year, and age at transplant. In conclusion, acute rejection, CsA dosage < 5 mg/kg/day at 1 year, and infection are the major risk factors for the development of chronic rejection, suggesting that chronic rejection may be the result of inadequate immunosuppression (acute rejection episodes and low CsA dosage) or the production of inflammatory cytokines (infections).

Adolescent↗
PubMed1993

Early versus late acute renal allograft rejection: impact on chronic rejection.

We studied the effect of acute renal allograft rejection and its timing on the development of chronic rejection and subsequent graft loss. Between January 1, 1987 and April 30, 1991, 424 patients at the University of Minnesota received a primary kidney transplant (minimum follow-up, 1 year). Patients were subdivided by donor source, presence or absence of acute rejection, and the timing of acute rejection onset (early, < or = 60 days vs. late, > 60 days post-transplant). For living donor (LD) transplant recipients (n = 219), the incidence of chronic rejection is 0.8% in those who had no acute rejection (n = 130), 20% in those with acute rejection < or = 60 days (n = 59) (P < 0.001 vs. no acute rejection), and 43% in those with acute rejection > 60 days (n = 30) (P < 0.001 vs. no acute rejection, P = 0.04 vs. early acute rejection). For cadaver (CAD) transplant recipients (n = 205), the incidence of chronic rejection is 0% in those who had no acute rejection (n = 109), 36% in those with acute rejection < or = 60 days (n = 69) (P < 0.001 vs. no acute rejection), and 63% in those with acute rejection > 60 days (n = 27) (P < 0.001 vs. no acute rejection, P = 0.03 vs. early acute rejection). For both LD and CAD recipients, no grafts have been lost to chronic rejection among those who did not first have at least 1 acute rejection episode. In contrast, 23 patients with acute rejection have had graft loss to chronic rejection. For both LD and CAD recipients, those with > 1 acute rejection episode had significantly more chronic rejection than those with only 1 rejection (P < 0.05). There was no significant difference in the incidence of chronic rejection based on whether the first acute rejection episode was steroid resistant or steroid responsive. We conclude that acute rejection is strongly related to the development of biopsy-proven chronic rejection and subsequent graft loss. Patients undergoing their first acute rejection episode > 60 days (vs. < or = 60 days) have an increased incidence of chronic rejection.

Acute Disease↗
PubMed1993

Acyclovir susceptibilities of herpes simplex virus strains isolated from solid organ transplant recipients after acyclovir or ganciclovir prophylaxis.

We determined the acyclovir (ACV) susceptibilities of herpes simplex virus (HSV) isolates (n = 18) recovered from solid organ transplant patients after antiviral prophylaxis with ACV or ganciclovir. All isolates tested were susceptible to ACV (50% inhibitory concentration, < 1 microM). A clinical review of patients with HSV disease showed that all improved with specific anti-HSV therapy, and no recurrences were reported.

Acyclovir↗
PubMed1992

High-performance liquid chromatographic determination of pilocarpine hydrochloride and its degradation products using a beta-cyclodextrin column.

A high-performance liquid chromatographic (HPLC) method for the determination of pilocarpine, isopilocarpine, pilocarpic acid and isopilocarpic acid was developed. A beta-cyclodextrin column achieved the separation in less than 10 min. Baseline resolution of all four compounds permitted the determination of each degradation product in the presence of pilocarpine. The calibration graphs for each compound were linear, and pilocarpine degradation products could be determined without a correction for the ultraviolet detector response using a pilocarpine standard. A comparison of beta-cyclodextrin separation with the USP HPLC method demonstrated similar results for pilocarpine contents in several commercial ophthalmic formulations.

Chromatography, High Pressure Liquid↗
PubMed1992

Analysis of infectious complications occurring after solid-organ transplantation.

To improve our understanding of posttransplant infections, we analyzed bacterial, viral, fungal, parasitic, and other infections in 604 consecutive recipients of kidney (n = 518), kidney-pancreas (n = 82), kidney-liver (n = 3), or kidney-islet (n = 1) allografts (355 cadaveric, 14 living-unrelated, 235 living-related donors) who also received cyclosporine, azathioprine, and prednisone immunosuppression. Recipients of cadaveric grafts received additional induction immunosuppression (antilymphocyte globulin or murine monoclonal antibody OKT3). Rejection episodes were treated with high-dose steroids, and either antilymphocyte globulin or OKT3 was administered when clinically indicated. Perioperative antibiotics and posttransplant prophylactic acyclovir sodium or ganciclovir sodium, trimethoprim-sulfamethoxazole, and clotrimazole or nystatin (Mycostatin) were administered to all recipients. Two hundred thirteen patients (35.3%) were found to have had no identifiable infections, while 391 (64.7%) had either isolated bacterial (97 [16.1%]), viral (53 [8.8%]), or fungal (34 [5.6%]) infections or combination (concurrent or sequential) infections with bacterial plus viral (46 [7.6%]), bacterial plus fungal (66 [10.9%]), viral plus fungal (20 [3.3%]), bacterial plus viral plus fungal (64 [10.6%]), or bacterial plus viral plus fungal plus parasitic (11 [1.8%]) pathogens in the posttransplantation period. Renal allograft survival (percentage, actuarial method) was diminished in patients with infections at both 1 year (91% vs 83%) and 3 years (81% vs 76%) after transplantation, as was actuarial patient survival (1 year, 97% vs 92%; 3 years, 93% vs 88%). We conclude that infection remains a major cause of both patient demise and allograft loss following successful solid-organ transplantation.

Adolescent↗
PubMed1992

Selective gut decontamination reduces nosocomial infections and length of stay but not mortality or organ failure in surgical intensive care unit patients.

Suppression of the gut luminal aerobic flora to reduce nosocomial infections was tested in a prospective, randomized, double-blind, placebo-controlled clinical trial in patients in a surgical intensive care unit who had persistent hypermetabolism. Forty-six patients were randomized to receive either norfloxacin, 500-mg suspension every 8 hours, together with nystatin, 1 million units every 6 hours, or matching placebo solutions administered through a nasogastric tube within 48 hours of surgical intensive care unit admission. Selective gut decontamination with the experimental therapy or placebo solutions continued for at least 5 days or until the time of surgical intensive care unit discharge. Patients were monitored with routine surveillance cultures for the development of nosocomial infections, as defined by criteria from the Centers for Disease Control. All other therapy was given as clinically indicated, including systemic antibiotics. The selective gut decontamination group experienced a significant reduction in the incidence of nosocomial infections and a reduced length of stay. However, these results were not associated with a concomitant decrease in progressive multiple organ failure syndrome, adult respiratory distress syndrome, or mortality.

Adult↗