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Biomedical subjects

M Dunn

Publications and source records attributed to M Dunn.

At least 73 records · Page 4Linked to original sources

Ventilator-associated pneumonia caused by Pseudomonas infection.

So far, P. aeruginosa has matched each new therapeutic advance with an antibiotic resistance or toxin move of its own. The result has been a persistently high mortality rate for Pseudomonas pneumonia, which is unacceptable. Further research to define aspects of the organism important in infection and to determine more effective treatment and prevention strategies are clearly needed.

Aminoglycosides↗

Determination of glomerular filtration rate with radionuclide renography and direct urinary activity quantitation.

OBJECTIVE: The direct urinary activity quantitation method is quick (approximately 40 minutes), requires only a single blood sample, is performed as part of standard renal scanning and shows high accuracy compared with 24-hour creatinine clearance. The purpose was to evaluate the practical application and accuracy of this technique at our clinic. DESIGN: Direct urinary activity quantitation was done in patients scheduled for routine radionuclide renography and compared to standard multiple-blood-sample techniques by means of Cr-51-EDTA and Tc-99m-DTPA. SETTING: Academic Medical Complex, Department of Nuclear Medicine, Universitas Hospital, Bloemfontein. PARTICIPANTS: Fifteen patients scheduled for routine radionuclide renography (glomerular filtration rate (GFR) determination) were voluntarily enrolled in the study. The GFRs of selected patients varied over a wide range. Possible obstructive uropathy was excluded. MAIN OUTCOME MEASURES: GFRs obtained by the direct urinary method were compared with GFRs determined by multisample Cr-51-EDTA and Tc-99m DTPA. RESULTS: GFRs from the direct urinary method compared with multisample Tc-99m-DTPA showed differences from -19.85 to 22.95 ml/min with a mean of 0.2 (+/- 12.25) ml/min (r = 0.93). When compared with multisample Cr-51 EDTA, differences ranged from -34.35 to 21.05 ml/min with a mean of -4.25 (+/- 16.08) ml/min (r = 0.90). CONCLUSION: The direct urinary activity technique is CONCLUSION: The direct urinary activity technique is easily applied and highly accurate compared with previous standardised multisample radionuclide techniques for determination of GFR.

Adolescent↗

Ureteric stricture formation following ureteric instrumentation in patients with a nephrostomy drain in place.

OBJECTIVE: To determine what effect the presence of a nephrostomy, left on free drainage, might have on the rate of occurrence of ureteric strictures after ureteric instrumentation. PATIENTS AND METHODS: Eighteen patients were identified in this unit who had had ureteric instrumentation while a nephrostomy was in place. RESULTS: Eight of 11 patients in whom the nephrostomy was left open developed ureteric strictures. None of seven patients in whom the lumen was maintained by stenting and/or clamping of the nephrostomy developed strictures. The strictures needed dilatation and stenting in seven patients and the ureter had to be reimplanted in the other. CONCLUSION: In patients in whom a nephrostomy is in place, the opening should be occluded after ureteric instrumentation or a stent should be inserted if it is to be left on free drainage.

Adult↗

Chronic family adversity and early child behavior problems: a longitudinal study of low income families.

A beginning step in the prevention of child psychopathology is the identification of conditions associated with a disproportionately high incidence of behavior problems. Rutter and colleagues (British Journal of Psychiatry, 1975, 126, 493-509) have reported a dramatic increase in the probability of child adjustment difficulties as a function of multiple family stressors. However, few investigators have tested this association beginning in infancy. The present investigation examines this relationship at the ages of 1 and 2 with behavioral adjustment at age 3 among 100 low-income families. Broad support was found for the family adversity hypothesis, though sex differences were evident regarding individual correlates of problem behavior.

Adaptation, Psychological↗

Serological response to Ureaplasma urealyticum in the neonate.

A serovar-specific antibody response to Ureaplasma urealyticum was observed in stillborns, neonates, and mothers by means of the modified metabolic inhibition test. Elevated levels of ureaplasma antibody were found in cases of stillbirth and neonatal respiratory disease. There was a higher risk of mortality among neonates with respiratory disease who had elevated levels of ureaplasma antibody. IgG and IgM serovar-specific antibody responses to U. urealyticum serovars were confirmed by the immunoperoxidase and immunofluorescence assays. In contrast to ELISA-based assays that use soluble membrane proteins as antigen, these three assays use whole intact cells. These observations suggest that the serovar-specific antibody response may be associated with the ureaplasma extramembranous carbohydrate (lypoglycan) coat, which comes off during centrifugation. With the immunoperoxidase assay, a heel-prick blood sample (20 microL) can be screened for 16 IgM or IgG + IgM + IgA (combined) responses in 4 hours. The predictive value of IgM antibody for U. urealyticum infection and other mycoplasma infections and for the risk of stillbirth and development of chronic lung disease should now be assessed.

Antibodies, Bacterial↗

Surfactant therapy in full-term neonates with severe respiratory failure.

OBJECTIVE: In light of the paucity of published data on the use of surfactant in full-term infants with respiratory failure due to meconium aspiration syndrome and respiratory distress syndrome, we report our experience with this therapy. Our goal was to explore possible justification for randomized controlled trials of surfactant treatment in similar patients at an earlier, less severe stage of the disease. METHODS: Retrospective consecutive case series of 20 infants with severe meconium aspiration syndrome and 29 infants with severe respiratory distress syndrome who received bovine surfactant between March 1990 and December 1992 in three neonatal intensive care units in a regionalized setting. Outcome of treatment was assessed by comparing changes in several respiratory indices including the oxygenation index, between 4 and 6 hours and 1 and 3 hours before and after the first dose of surfactant. Differences were analyzed using analysis of variance for repeated measures, with treatment and time as co-variates. RESULTS: In the meconium aspiration group the mean oxygenation index decreased from 36 +/- 12 at 1 to 3 hours presurfactant to 24 +/- 14 at 1 to 3 hours postsurfactant (P < .001). In the patients with respiratory distress syndrome the mean oxygenation index fell from 30 +/- 17 at 1 to 3 hours presurfactant to 12 +/- 6 at 1 to 3 hours postsurfactant (P = .0001). Three of 20 patients with meconium aspiration syndrome and 3 of 29 patients with respiratory distress syndrome received extracorporeal membrane oxygenation. CONCLUSIONS: Surfactant therapy in full-term infants with respiratory failure due to the meconium aspiration and respiratory distress syndromes is often effective in improving gas exchange. A randomized controlled trial of surfactant therapy at an earlier stage in the course of the illness should be performed.

Gestational Age↗

Antisense-mediated specific inhibition of P120 protein expression prevents G1- to S-phase transition.

A pentadecadeoxyribonucleotide (5'-AAAGCCCCCCACCAC), complementary to a splice junction site of mRNA for human proliferation-associated nucleolar protein P120, inhibited expression of the P120 gene and the mitogen-induced proliferation of human lymphocytes. The inhibition of P120 gene expression and proliferation was concentration dependent and reached 90% at 200 microM, as measured by [3H]thymidine uptake and by densitometric scanning of Northern (mRNA) and Western (protein) blots of P120. Inhibition was not observed in cells treated with the correspondent nonsense oligomer. P120 antisense oligomer treatment prevented S-phase entry of mitogen-stimulated lymphocytes, as determined by flow cytometric analysis, but did not block G0-G1 transition assessed by morphological blast transformation and induction of [3H]uridine incorporation. Results of this study suggest that P120 expression may be required for the upregulation of nucleolar function necessary for cell proliferation.

Base Sequence↗

Latex agglutination testing directly from throat swabs for rapid detection of beta-hemolytic streptococci from Lancefield serogroup C.

A latex agglutination method for the rapid detection of beta-hemolytic streptococci from Lancefield serogroup C in throat swabs from 403 university students with symptomatic pharyngitis was evaluated. Compared with culture, the rapid test was poorly sensitive (34.4%) but very specific (98.4%) in detecting group C beta-hemolytic streptococci. The sensitivity of the rapid test improved with an increasing quantity of growth on culture.

Adolescent↗

Pulmonary embolism in younger adults.

To test the hypothesis that the clinical presentation and outcomes are different when pulmonary embolism occurs in younger (age 18 to 40 years) as compared to older (age greater than 40 years) adults, 40 younger patients were compared with older patients. No risk factors could be identified in 28 percent of the younger group. Normal physical examinations were more common (58 vs 28 percent, p = 0.01) among younger as compared with older adults. Hypoxemia was absent in 29 percent of the younger and 3 percent of the older group (p = 0.004); P(A-a)O2 was significantly lower among younger patients even after controlling for age. Mortality was decreased sevenfold (2.5 vs 18 percent, p = 0.03) among younger patients. These data indicate that pulmonary embolism tends to have a subtle presentation in younger adults. When diagnosed and treated, the mortality rate is substantially less among younger as compared with older patients.

Adolescent↗

Anticoagulant treatment of atrial fibrillation in the elderly.

There is now adequate clinical evidence that the most appropriate treatment of elderly patients with non-valvular atrial fibrillation is with low dose warfarin. Patients may have contraindications to therapy with this agent, but should not be denied treatment based on age alone. Withholding treatment based on age places patients at unwarranted risk for severely disabling thromboembolic complications.

Aged↗

Clam enterocystoplasty in general urological practice.

A series of 45 patients (31 female) underwent clam enterocystoplasty for urgency and incontinence. The majority had detrusor instability. Prolonged conservative treatment had failed in all cases. Improvement occurred in 71% and those younger than 30 years had better overall results; 29% remained incontinent, with 9% requiring a urinary diversion. Many patients did not achieve maximum benefit until 9 months post-operatively. Surgery had no statistically significant effect on any urodynamic parameter and post-operative complications were common. The operation was performed in either the coronal (19) or the sagittal plane (26); this did not influence results. In general, surgery was found to be technically simpler in the sagittal group and it is recommended that this becomes the standard procedure. We feel that this operation involves major surgery and should only be offered with reluctance.

Adult↗

Characterization of murine polyclonal antisera and monoclonal antibodies generated against intact and denatured human papillomavirus type 1 virions.

Human papillomavirus type 1 (HPV1) virions, both as intact virion particles (IVP) and as detergent-denatured virions (DDV), were used to prepare polyclonal antisera and monoclonal antibodies (MAbs) in BALB/c mice. Anti-IVP antiserum contained type-specific HPV1 L2-reactive antibodies and no detectable HPV1 L1-reactive antibodies. Anti-IVP MAbs recognized a linear epitope between L2 amino acids 102 and 108 (PIDVVDP). Anti-DDV antiserum contained type-specific HPV1 L1-reactive and HPV1 L2-reactive antibodies. An anti-DDV MAb recognized a linear epitope between L1 amino acids 127 and 133 (AENPTNY). HPV1a L1- and L2-encoded polypeptides expressed in Saccharomyces cerevisiae and by in vitro translation were equivalent in size to the major and minor virion capsid proteins, respectively.

Amino Acid Sequence↗

Effects of endothelin on cultured human and rat glomerular mesangial cells.

Figure 5 summarizes our results and the data in the literature with regard to both short-term signalling and long-term signalling induced by endothelin. Short-term signalling, which induces vasoconstriction, is undoubtedly mediated by multiple signals including increments of cytosolic calcium, stimulation of protein kinase C and alkalinization of the cytosol. Endothelin also activates negative feedback pathways including arachidonate release with the synthesis of vasorelaxant prostaglandins and potentiation, in a prostaglandin-dependent manner, of beta-adrenergic-stimulated adenylate cyclase. Long-term signalling is less well understood and may depend not only on phospholipase activation with subsequent changes of calcium and protein kinase C but also stimulation of other protein kinases which phosphorylate key intermediates. Endothelin stimulates the transient appearance of protooncogenes that might play a role in the induction of cellular proliferation.

Animals↗

Contribution of the bronchial circulation to lung preservation.

Short preservation time still severely limits lung transplantation. To determine the effect of bronchial arterial flush preservation, we studied 54 dogs using the isolated perfused working lung model. After baseline measurements, lungs were flushed with lactated Ringer's solution (60 ml/kg at 8 degrees C) by one of three methods: pulmonary artery perfusion, bronchial artery perfusion through a 15 cm closed aortic segment, or simultaneous pulmonary-bronchial artery perfusion. These groups were further subdivided and tested after 0, 4, and 17 hours of storage at 4 degrees C (n = 6 each). Lungs were ventilated (flow rate 140 ml/kg/min; inspired oxygen fraction 0.21) and continuously reperfused with normothermic deoxygenated autologous blood in a closed loop. Measured variables were hemodynamics, aerodynamics, and leukocytes in bronchoalveolar lavage. Survival time was determined from initial reperfusion to failure of the lung to oxygenate. After 0 and 4 hours of storage, there was no significant difference in survival times. After 17 hours, lungs subjected to pulmonary-bronchial artery perfusion survived longer than those perfused via either the pulmonary or bronchial arteries alone (120 +/- 24 versus 38 +/- 14 or 52 +/- 16 minutes; p less than 0.01). Pulmonary artery pressure and resistance in all groups except at failure were never different from baseline values in the intact animal. Shunts in the pulmonary-bronchial artery perfusion groups were closest to baseline at onset (8% +/- 4%) and remained lower throughout reperfusion than in the groups subjected to pulmonary or bronchial artery perfusion alone. After 17 hours, static compliance of pulmonary artery-perfused lungs was worse than baseline (1.1 +/- 0.2 x 10(-2) versus 3.2 +/- 0.7 x 10(-2) L/cm H2O/sec; p less than 0.05), whereas compliance in the pulmonary-bronchial artery perfusion groups remained constant (3.6 +/- 1.5 x 10(-2) L/cm H2O/sec). Elastic work performed by lungs subjected to pulmonary-bronchial artery flushing at onset was significantly lower when these lungs were reperfused immediately (201 +/- 14 versus 295 +/- 35 gm-m/min for pulmonary artery-flushed lungs) or after 4 hours of storage (229 +/- 30 versus 290 +/- 24 gm-m/min for pulmonary artery-flushed lungs). Bronchoalveolar lavage after 17 hours in the group subjected to pulmonary bronchial artery flushing demonstrated leukocyte counts similar to those of intact lungs (45 +/- 5 versus 29 +/- 8/mm3) and significantly less than in lungs subjected to pulmonary or bronchial artery flushing (137 +/- 18 or 82 +/- 10/mm3, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

[A comparison of three different techniques for measuring glomerular filtration rate].

The clearance of inulin, creatinine and radioactive tracers from the blood may be used to measure glomerular filtration rate (GFR). These techniques, however, are usually invasive and time-consuming. Although the clearance of a radioactive tracer is usually applied in nuclear medicine for the determination of GFR, it is also possible to convert the concentration of the tracer in the kidneys to absolute GFR by means of a regression equation. As this new technique is much faster, we have compared it with the conventional technique. A good correlation was found with the standard radionuclide techniques (r = 0.91), but the reference method was under-estimated on the average by 14 ml/min. The new regression equation derived in our clinic will ensure future accurate GFR measurements within 6 minutes.

Chromium Radioisotopes↗