PubMed Health⌕ Search

Biomedical subjects

J Mundy

Publications and source records attributed to J Mundy.

61 records · Page 4Linked to original sources

Iron transport in Mycobacterium smegmatis: the location of mycobactin by electron microscopy.

Mycobactin, the lipid-soluble iron-binding compound of the mycobacteria, has been located using electron microscopy of whole cells stained with vanadate. It forms a discrete, discontinuous region close to, or even included in, the cytoplasmic membrane of Mycobacterium smegmatis. It does not occur throughout the whole thickness of the wall but is some distance within the envelope. Possible models for the accommodation of mycobactin are discussed. It is concluded from these observations that mycobactin may be acting either as a store of iron, or as an ionophore, or possibly fulfilling both roles.

Cell Membrane↗

Initial steroid-free versus steroid-based maintenance therapy and steroid withdrawal after heart transplantation: two views of the steroid question.

To determine any benefit of maintenance steroids in a cyclosporine and azathioprine immunosuppressive regimen, 112 heart transplant recipients were prospectively randomized to receive cyclosporine, azathioprine, and prednisolone (n = 59) or cyclosporine and azathioprine (n = 53). Of the 53 double-therapy patients, 47% were converted to maintenance steroids for resistant rejection or renal dysfunction. In a comparison of true double-therapy (n = 28) versus true triple-therapy (n = 59) groups, actuarial survival and systolic function did not differ. Linearized rejection during the first 3 months was lower with triple therapy than with double therapy (1.5 +/- 0.18 vs 2.3 +/- 0.23 episodes/100 patient-days; p less than 0.01) as were requirements for cytolytic therapy for rejection with hemodynamic compromise. Patients receiving triple therapy had significantly higher serum cholesterol levels and antihypertensive agent requirements at all annual time points up to 5 years. The rate of steroid-related morbidity (diabetes, bone complications, cataracts, and obesity) was low in both groups and did not differ significantly. Of the 204 patients receiving triple therapy at this unit, 45 underwent steroid withdrawal. The initial success rate was 69%, and an additional 14% of those who initially failed succeeded on the second attempt. Any rejection after steroid cessation tended to occur within 6 weeks. There were, however, no substantial short-term benefits in body weight or lipid or blood pressure control. In patients in whom infection or growth retardation was an indication for steroid withdrawal, these generally improved after cessation. Until predictive markers for the likely success of steroid withdrawal are identified, the case for steroid withdrawal, as opposed to steroid minimization, does not seem compelling.

Adult↗

Five-year follow-up of a randomized double-drug versus triple-drug therapy immunosuppressive trial after heart transplantation.

To determine the role of maintenance steroids in a cyclosporine and azathioprine immunosuppressive regimen, 112 heart transplant recipients were prospectively randomized to group I (n = 59; cyclosporine, azathioprine, and prednisolone) or group II (n = 53; cyclosporine and azathioprine). All patients received 7 days of induction with antithymocyte globulin. Patients receiving double-drug therapy who required four treatments for rejection were converted to maintenance steroids. This was necessary in 47% of the patients. Actuarial survival at 5 years was 82% in group I and 85% in group II. Linearized rejection in the first 3 months was lower with triple-drug therapy than with double-drug therapy (1.5 +/- 0.18 versus 2.3 +/- 0.23 episodes/100 patient days, p less than 0.01) but did not differ beyond 3 months. No significant differences were noted in 3-year left ventricular ejection fraction (0.56 +/- 0.09 versus 0.58 +/- 0.12 units), serum creatinine level (0.14 +/- 0.04 versus 0.14 +/- 0.03 mmol/L), or number with coronary artery disease (10 versus 13), diabetes, or bone complications. Patients receiving triple-drug therapy, however, had higher serum cholesterol level at 3 years (6.2 +/- 0.9 versus 5.4 +/- 1.2 mmol/L; p = 0.022) and required more antihypertensive agents (1.3 +/- 0.8 versus 0.8 +/- 0.6; p = 0.016). Similar trends emerged when patients receiving true double-drug therapy were compared with those patients who were "converted." Therapy with double versus triple immunosuppressive therapy results in similar 5-year survival and systolic function, using this protocol of converting recurrent rejectors on double-drug therapy to maintenance steroids.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

Upregulation of epidermal growth factor and its receptor in the kidneys of rats with streptozotocin-induced diabetes.

We have studied the acute changes (up to 30 days) in the expression of epidermal growth factor (EGF) and its receptor (EGFr) in the kidneys of adult male Wistar rats made diabetic by a single intravenous injection of streptozotocin (55 mg/kg) using a combination of immunocytochemical staining and in situ hybridization histochemistry. In the absence of insulin treatment, diabetic rats displayed renal growth (hypertrophy and hyperplasia). It was accompanied by an increase in immunostainable EGF within the thick ascending limb (TAL) of the loops of Henle which was apparent within 24 h of the onset of diabetes, reached a peak by day 7 and persisted to the end of the experimental period (day 30). In situ hybridization histochemistry revealed that these changes were preceded by a rapid rise in EGF mRNA in the cells of the TAL, which was highest after 1 day but declined to control levels by day 7. Increased immunostainable EGFr was evident in both the proximal and TAL and in the cortical collecting ducts from day 1. Staining of the proximal tubules declined rapidly after day 1 but that of the TAL and collecting ducts persisted until day 7 and declined thereafter. These results are discussed in light of the role of EGF in the hypertrophy and repair of the diabetic kidney.

Animals↗