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M Jordan

Publications and source records attributed to M Jordan.

At least 55 records · Page 3Linked to original sources
PubMed1996

Transfecting mammalian cells: optimization of critical parameters affecting calcium-phosphate precipitate formation.

DNA-calcium phosphate co-precipitates arise spontaneously in supersaturated solutions. Highly effective precipitates for transfection purposes, however, can be generated only in a very narrow range of physico-chemical conditions that control the initiation and growth of precipitate complexes. The concentrations of calcium and phosphate are the main factors influencing characteristics of the precipitate complex, but other parameters, such as temperature, DNA concentration and reaction time are important as well. An example for this is the finding that almost all of the soluble DNA in the reaction mix can be bound into an insoluble complex with calcium phosphate in <1 min. Extending the reaction time to 20 min results in aggregation and/or growth of particles and reduces the level of expression. With improved protocols we gained better reproducibility and higher efficiencies both for transient and for stable transfections. Up to 60% of cells stained positive for beta-gal and transient production of secreted proteins was improved 5- to 10-fold over results seen with transfections using standard procedures. Similar improvements in efficiency (number of recombinant cell colonies) were observed with stable transfections, using co-transfected marker plasmids for selection. Transient expression levels 2 days after DNA transfer and titers obtained from stable cell lines, emerging weeks later, showed strong correlation.

Animals↗
PubMed1996

Restoration of vascular endothelial function in diabetes.

Nitric oxide (NO) is believed to mediate the phenomenon known as endothelium-dependent relaxation (EDR). NO synthase produces NO from its precursor, arginine (ARG). We have previously demonstrated impaired EDR in diabetic blood vessels. In this study, we investigated a possible mechanism for defective EDR in experimental diabetes and whether pancreatic islet transplantation could reverse established endothelial dysfunction. Streptozotocin-induced diabetic rats were maintained for 8 or 12 weeks. NO-mediated EDR was assessed in isolated thoracic rings ex vivo. A group of untreated diabetic rats received syngeneic islet transplantation at 8 weeks of diabetes and were tested for EDR after 4 weeks of euglycemia. EDR to acetylcholine was impaired in untreated diabetic rings. Endothelium-independent relaxation to nitroglycerin was unaltered. In vitro incubation of diabetic rings with 3 mM L-ARG (but not D-ARG) improved EDR to acetylcholine in rings from 8-week but not 12-week diabetic rats. L-ARG did not alter EDR in control rings nor relaxation to nitroglycerin in control or diabetic rings. Islet transplantation at 8 weeks of diabetes normalized blood glucose, plasma arginine and total glycosylated hemoglobin while restoring normal EDR. In conclusion, a defect in substrate/supply for NO synthesis is acutely reversed by ARG supplementation at early but not at later stages of diabetes. Also, preemptive surgical intervention with islet transplantation prior to the ARG-insensitive phase is an effective strategy to reverse established endothelial dysfunction in diabetes mellitus.

Animals↗
PubMed1996

An immunocytochemical study of H+ ATPase in kidney transplant rejection.

Kidney transplant rejection may be accompanied by defective urinary acidification. Its pathogenesis is unknown. There are shared histologic features between kidney transplant rejection and the distal renal tubular acidosis (RTA) of Sjogren syndrome, which led us to hypothesize that deficient collecting duct H+ adenosine triphosphatase (ATPase) expression--which is lacking in the RTA of Sjogren syndrome - may cause the RTA of kidney transplant rejection. Six kidney transplant recipients with biopsy evidence for rejection and two control subjects were studied physiologically and by immunohistochemistry. We found defective urinary acidification in all 6 kidney transplant patients. Ammonium excretion was diminished in relation to the degree of azotemia. There was an abnormal response to furosemide in all 6, suggesting distal tubular dysfunction. Distal H+ ATPase staining was reduced in relation to the degree of azotemia, although it was not totally absent even in the worst case. This was paralleled by the urinary PCO2 response. Both control subjects had good urine PCO2 and H+ ATPase staining and adequate urine pH response to furosemide. They had reduced urinary ammonium (NH4) concentrations in relation to modest azotemia. We conclude that kidney transplant rejection may be accompanied by defective urinary acidification, which is not primarily due to a lack of H+ ATPase. The RTA of kidney transplant rejection appears to result from defective ammonium excretion, generalized distal tubular malfunction, and--in severe cases--from a reduction in distal nephron H+ ATPase expression.

Acidosis, Renal Tubular↗
PubMed1996

Repression of hybrid dysgenesis in Drosophila melanogaster by heat-shock-inducible sense and antisense P-element constructs.

Sets of sense and antisense P-element constructs controlled by a heat-shock-inducible promoter were tested for their ability to repress manifestations of P-element activity in vivo. As a group, the antisense constructs repressed pupal lethality, a somatic manifestation of P activity, and this repression was significantly enhanced by heat shock. Three of the 11 antisense constructs also repressed gonadal dysgenesis, a manifestation of P activity in the female germ line; however, none had any effect on P-element-mediated mutability in the male germ line. Among the 13 different heat-shock-inducible sense constructs that were tested, those containing the KP and DP elements were strong repressors of pupal lethality, gonadal dysgenesis and P-element-mediated mutability; however, individual lines carrying these constructs varied in their ability to repress each of these traits, presumably because of genomic position effects. With the exception of the sense construct that contained a complete P element, none of the sense or antisense constructs repressed a lacZ reporter gene driven by the P-element promoter. Overall, the experimental results suggest that in nature, P-element activity could be regulated by P-encoded polypeptides and by antisense P RNAs.

Animals↗
PubMed1996

Microvascular changes in renal allografts associated with FK506 (Tacrolimus) therapy.

FK506 (Tacrolimus) recently has been shown to be an effective immunosuppressant after renal transplantation. It is associated with less hypertension, hypercholesterolemia and steroid use compared with cyclosporine. We report 10 patients on FK506 who showed fibrin thrombi within the glomerular capillaries and/or arterioles at renal allograft biopsy. These biopsies were generally performed to assess increasing serum creatinine levels; laboratory evidence of hemolytic uremic syndrome was present in one instance. Plasma or whole blood FK506 levels were elevated in eight of 10 cases. Reduction of immunosuppression led to clinical improvement or biopsy-proven resolution of thrombi in all cases. These observations suggest that FK506 may occasionally produce microvascular changes in the renal allograft. The estimated incidence of this occurrence (1%) is comparable with that reported with cyclosporine (3%).

Adult↗
PubMed1996

Renal allograft involvement by Epstein-Barr virus associated post-transplant lymphoproliferative disease.

This study describes nine cases of post-transplant lymphoproliferative disease (PTLD) presenting as renal allograft dysfunction. Onset of symptoms was 34 to 265 days post-transplant, typically (in six of nine cases) after refractory rejection treated with OKT3. Diagnosis was made by histopathologic examination of needle biopsy (three of nine cases) or allograft nephrectomy (six of nine cases) specimens. Disease was confined to the allograft in three patients. The morphology was polymorphic in eight cases and monomorphic in one case. Five cases showed monotypic kappa or lambda light chain expression. Expansile lymphoid infiltrates, serpiginous necrosis, nuclear atypia, and presence of Epstein-Barr virus RNA helped to distinguish PTLD from severe rejection. Tubular damage and venulitis was common in PTLD lesions, but arterial involvement was not prominent. Infiltration of the ureter, hilar adipose tissue, and nerve twigs was frequent in nephrectomy specimens. Reduction of immunosuppression led to resolution of PTLD in two of three cases diagnosed by needle biopsy, but severe acute rejection led to graft loss in one case; the third case progressed to fatal multisystem disease. Among cases diagnosed at nephrectomy, two of six patients died of disseminated PTLD and one of six died of sepsis. The five surviving patients are alive 41 to 99 months after initial diagnosis without evidence of recurrent PTLD.

Adult↗
PubMed1996

Chronic treatment in vivo with dimethylthiourea, a hydroxyl radical scavenger, prevents diabetes-induced endothelial dysfunction.

Oxidative stress is believed to play a role in diabetes-induced vascular complications. In this study, we tested whether chronic treatment with a known hydroxyl radical scavenger, dimethylthiourea (DMTU), could prevent endothelial dysfunction in diabetes. Lewis strain rats were made diabetic by an intravenous injection of streptozotocin. A subgroup of diabetic animals received daily intraperitoneal injections of 50 mg/kg DMTU beginning at 72 h after streptozotocin and throughout 8 weeks of diabetes. Diabetes caused an increase in aortic catalase activity (an index of compensatory in vivo oxidative stress) that was not prevented by long-term DMTU treatment. Long-term treatment of diabetic animals with DMTU did not alter serum insulin levels, blood glucose concentrations, or total glycosylated hemoglobin. Descending thoracic aortas were isolated, sectioned into rings and suspended in isolated tissue baths, and contracted with a submaximal concentration of norepinephrine. Relaxation to the endothelium-dependent vasodilator, acetylcholine, was impaired in diabetic aortas, whereas relaxation to A23187 and nitroglycerin was unaltered. DMTU treatment prevented the diabetes-induced impairment in endothelium-dependent relaxation to acetylcholine but had no effect on relaxations induced by either A23187 or nitroglycerin. These data suggest that chronic exposure to increased levels of hydroxyl radicals in vivo likely play a significant role in the origin of diabetes-associated endothelial dysfunction.

Acetylcholine↗
PubMed1996

Accuracy of four commercial systems for identification of Burkholderia cepacia and other gram-negative nonfermenting bacilli recovered from patients with cystic fibrosis.

Burkholderia cepacia has recently been recognized as an important pathogen in chronic lung disease in patients with cystic fibrosis (CF). Because of the social, psychological, and medical implications of the isolation of B. cepacia from CF patients, accurate identification of this organism is essential. We compared the accuracies of four commercial systems developed for the identification of nonfermenting, gram-negative bacilli with that of conventional biochemical testing for 150 nonfermenters including 58 isolates of B. cepacia recovered from respiratory secretions from CF patients. The accuracies of the four systems for identifying all nonfermenters ranged from 57 to 80%, with the RapID NF Plus system being most accurate. The accuracies of these systems for identifying B. cepacia ranged from 43 to 86%, with the Remel system being most accurate. Depending on the commercial system, from two to seven isolates were misidentified as B. cepacia. The relatively poor performance of the commercial systems requires that identification of certain nonfermenters be confirmed by conventional biochemical testing. These organisms include B. cepacia, Burkholderia sp. other than B. cepacia, and infrequently encountered environmental species (Pseudomonas and Flavobacterium species). In addition, conventional biochemical testing should be done if a commercial system fails to assign an identification to an organism. Confirmatory testing should preferably be performed by a reference laboratory with experience in working organisms isolated from CF patients.

Bacteriological Techniques↗
PubMed1995

Combined simultaneous kidney/bone marrow transplantation.

On the basis of observations in patients with long-term (28-30 years) renal allograft survival, all of whom had evidence of systemic microchimerism, we began a program of combined simultaneous kidney/bone marrow transplantation. Between 12/14/92, and 10/31/94, 36 kidney transplant recipients received 3-5 x 10(8) unmodified bone marrow cells/kg; 6 patients also received pancreatic islets, and 7 patients also received a pancreas. The mean recipient age was 39.0 +/- 10.8 years, and the mean donor age was 31.8 +/- 16.1 years; the mean cold ischemia time was 23.0 +/- 9.1 hr. Twenty control patients received kidneys alone, mainly because of refusal by the donor family to consent to vertebral body recovery; 3 of these patients also received a pancreas. The mean recipient age was 47.9 +/- 11.7 years, and the mean donor age was 41.5 +/- 17.9 years; the mean cold ischemia time was 28.6 +/- 6.2 hr. All patients received tacrolimus-based therapy, without radiation, cytoreduction, or induction antilymphocyte preparations. Blood was drawn prior to and at regular intervals after transplantation for detection of chimerism and for immunologic studies. With a mean follow-up of 11.1 +/- 5.8 months, all 36 study patients are alive, and 33 (92%) have functioning allografts with a mean serum creatinine of 1.9 +/- 1.2 mg/dl and a BUN of 26 +/- 9 mg/dl. Graft vs. host disease was not seen in any patient. The incidence of rejection was 72%; 11% of the patients required OKT3 or ATG for steroid-resistant rejection. The incidence of CMV was 14%, and that of delayed graft function was 17%. A total of 18 (90%) control patients are alive, and 17 (85%) have functioning allografts, with a mean serum creatinine of 2.1 +/- 1.3 mg/dl, and a BUN of 30 +/- 13 mg/dl. The incidence of rejection was 60%, and 10% required OKT3 or ATG. CMV was seen in 15%, and delayed graft function in 20% (P = NS). In the study patients, chimerism was detected in the peripheral blood of 30 of 31 (97%) evaluable patients by either PCR or flow cytometry. In the control patients, chimerism was seen in 9 of 14 (64%) evaluable patients (P < .02). Decreasing donor-specific responsiveness was seen in 6/29 (21%) evaluable study, and 4/14 (29%) evaluable control patients (P = NS). We conclude that combined kidney/bone marrow transplantation is associated with acceptable patient and graft survival, augmentation of chimerism, and no change in the early events after transplantation.

Adolescent↗
PubMed1995

Neutralization of endogenous IL-6 suppresses induction of IL-1 receptor antagonist.

IL-1 is a potent cytokine that promotes host defense and inflammation. These processes may be modulated by an IL-1 receptor antagonist (IL-1Ra) that binds to and blocks IL-1 receptors. The objective of this study was to define the cellular origin and regulation of IL-1Ra production during bacterial infection. Oral infection of mice with Yersinia enterocolitica resulted in expression of IL-1Ra mRNA and synthesis of IL-1Ra in Peyer's patches (PP), the local site of infection, as well as in noninfected organs such as spleens. By immunostaining, recruited circulating neutrophils were identified to be the primary source of IL-1Ra in tissues. Only approximately 20% of the IL-1Ra-staining cells were accounted for by inflammatory macrophages. Strikingly, neutralization of IL-6 by anti-IL-6 antiserum caused a suppression of both IL-1Ra mRNA in PP and synthesis of IL-1Ra in circulating neutrophils. Confirmatory evidence that IL-6 participates in the generation of IL-1Ra was obtained when rIL-6 induced, and anti-IL-6 antiserum blocked, IL-1Ra expression in cultures of macrophage and polymorphonuclear leukocytes (PMN). These findings suggest that IL-6 induced induction of IL-1Ra may provide a negative feedback loop, facilitating resolution of the inflammatory response locally and presumably at remote sites of infection.

Animals↗
PubMed1995

How do smokers differ from nonsmokers in their response to thrombolysis? (the TIMI-4 trial)

Smokers with acute myocardial infarction appear to have a better outcome after thrombolysis than do nonsmokers. To identify factors that could contribute to this curious finding, we analyzed data from the Thrombolysis in Myocardial Infarction (TIMI-4) trial, in which 382 patients with acute myocardial infarction were randomized to tissue plasminogen activator, anistreplase, or both. Coronary angiography was performed 90 minutes and 18 to 36 hours after randomization, a myocardial perfusion scan was performed at 18 to 36 hours and before discharge, and a radionuclide ventriculogram was obtained before discharge. Angiographic and clinical outcome variables were determined in current smokers, ex-smokers, and nonsmokers, and regression analysis was used to correct for differences in baseline characteristics. The in-hospital mortality of current smokers was lower than that of ex-smokers and nonsmokers: 2.3% versus 5.2% versus 7.0%, respectively (p = 0.04 by paired comparison, current vs nonsmokers). Ninety minutes after randomization, the incidence of TIMI grade 3 flow was significantly higher in smokers than in ex-smokers and nonsmokers (55% vs 43% and 45%, p = 0.02); this difference was no longer observed at the second angiogram, nor did smokers differ from nonsmokers with respect to residual stenosis, thrombus grade, infarct size, ejection fraction, or recurrent ischemia. Because a strong inverse relation exists between TIMI grade 3 flow at 90 minutes and mortality, our findings suggest that the lower mortality of current smokers after thrombolytic therapy may be related to a higher incidence of early, complete reperfusion.

Double-Blind Method↗
PubMed1995

Thrombolytic Therapy for Acute Myocardial Infarction in Patients with Prior Coronary Bypass Surgery: Results from the Thrombolysis in Myocardial Infarction (TIMI) 4 Trial.

Little data exist on the value of intravenous thrombolysis for acute myocardial infarction in patients with previous coronary bypass surgery. The Thrombolysis In Myocardial Infarction (TIMI) 4 trial was a randomized study comparing tissue plasminogen activator, anistreplase, or a combination in patients with evolving myocardial infarction; patients with previous coronary bypass surgery were not excluded. Coronary angiography was performed 90 minutes and 18-36 hours after randomization, a myocardial perfusion scan was performed at 18-36 hours and predischarge, and a radionuclide ventriculogram was obtained predischarge. Angiographic and clinical outcome variables were determined in patients with and without a history of coronary bypass surgery. A total of 416 patients were randomized and 13 of them had previous bypass surgery; of these, 6 had an occluded vein graft as the infarct-related vessel. The incidence of TIMI grade 3 flow at 90 minutes was lower in patients with previous coronary surgery as compared with controls (42% vs. 49%), and overall patency was significantly lower (50% vs. 77%, p = 0.04). This trend persisted at 18-36 hours after randomization. Furthermore, patients with previous coronary surgery had more thrombus in their infarct-related arteries, especially with occlusion of a vein graft (83% vs. 32%, p = 0.04) and higher rates of recurrent ischemia (15% vs. 8%) and recurrent infarction (23% vs. 5%, p = 0.03) than controls. Thus, in patients with previous coronary bypass surgery intravenous thrombolysis yields results that are inferior to those achieved in patients without such a history and alternative methods of reperfusion should be considered.

Journal Article↗
PubMed1995

A double-blinded prospective evaluation of recombinant human erythropoietin in acutely burned patients.

OBJECTIVE: To evaluate the effects of recombinant human erythropoietin (r-HuEPO) in attempting to prevent anemia in acutely burned patients. DESIGN: Prospective double-blind randomized study of 40 patients. METHODS: Patients with burns from 25% to 65% total body surface were enrolled. r-HuEPO or a placebo was begun within 72 hours of admission. Cell blood count, reticulocyte counts, transfusion requirements, and blood loss were measured. Comparison was carried out by the unpaired t test. MAIN RESULTS: There was no statistically significant difference in hemoglobin, hematocrit, reticulocyte count, ferritin, serum iron, total iron blinding capacity, or transfusion requirements. In patients with burns from 25% to 35%, the reticulocyte counts were statistically significantly higher. CONCLUSION: In our work the administration of r-HuEPO in acutely burned patients did not prevent the development of postburn anemia or decrease transfusion requirements. Increased erythropoiesis in smaller burns (25% to 35%) was observed and may indicate a reason for further study.

Adolescent↗
PubMed1995

Comparison of antimicrobial susceptibility methods for detection of penicillin-resistant Streptococcus pneumoniae.

We sought to determine if commercially available susceptibility tests were accurate in detecting penicillin resistance and relative resistance in Streptococcus pneumoniae. We compared the reference MIC method with oxacillin disk screening and three commercial tests, E-test (AB Biodisk), JustOne (Radiometer America), and MicroScan Pos MIC Panel Type 6 (Baxter Diagnostics), with 80 selected clinical isolates. Thirty-three additional isolates were tested by the reference method and the E-test to further validate the latter method. Oxacillin screening was effective in detecting all penicillin-resistant and relatively resistant strains of S. pneumoniae. The MicroScan method was not effective in detecting penicillin resistance or relative resistance. The JustOne system classified only 6 (35%) of 17 resistant strains correctly, with 11 resistant strains classified as relatively resistant. The E-test correctly classified 30 (83%) of 36 resistant isolates, with 6 resistant isolates interpreted as relatively resistant. For determining penicillin MICs for S. pneumoniae, the E-test was the most accurate of the commercial systems that we studied.

Humans↗
PubMed1995

Attitudes to and use of baby walkers in Dublin.

OBJECTIVES: To identify the rate of baby walker use, parental attitudes, and associated injuries. DESIGN: Parents of babies attending clinics for developmental assessment were surveyed by self administered questionnaire about their use, attitudes, and history of injuries associated with walkers. SETTING: Dublin, Ireland. SUBJECTS: Parents of 158 babies. RESULTS: Fifty five per cent of the sample used a walker. The main reasons for doing so included babies' enjoyment of them and the fact that the walker was used for an older sibling. Although none of the users listed safety concerns as a reason to stop using the walker, non-users (45%) did so; 12.5% of the users had at least one walker related injury. CONCLUSIONS: Parents of babies who use a walker perceive them as beneficial. However these babies are placed at unnecessary risk. It behoves all health professionals and child carers to alert parents to these dangers and the sale of walkers should be reviewed.

Adult↗