Neuromelioidosis: Craniospinal MRI Findings in Burkholderia pseudomallei Infection

PURPOSE

To investigate magnetic resonance imaging (MRI) findings of central nervous system (CNS) infection with Burkholderia pseudomallei.

METHODS

Retrospective analysis of 10 patients (5 male and 5 female, age range from 13 to 69 years) with CNS melioidosis confirmed on culture of blood, sputum, cerebrospinal fluid, brain biopsy, and postmortem brain tissue. Clinical data were collected and MRI brain and/or spine were independently reviewed.

RESULTS

Seven patients with brain parenchymal or intramedullary spinal cord lesions demonstrated rim-enhancing microabscesses with propensity for white matter tracts including the corticospinal tracts, corpus callosum, and cerebellar peduncles. Three of these 7 patients also showed thickening and enhancement of the trigeminal nerves with contiguous spread to brain stem trigeminal nuclei. Three patients had isolated extraaxial disease with findings including meningeal enhancement, extradural abscess, skull osteomyelitis, and scalp abscess.

CONCLUSION

Spread of microabscesses along white matter tracts and frequent trigeminal nerve involvement are unique imaging characteristics of CNS melioidosis. These findings may provide insight into potential mechanisms for B. pseuodomallei entry into the CNS through direct axonal transport in cranial nerves bypassing the blood brain barrier. Prompt recognition of the neuroimaging features of this potentially fatal infection may allow for early microbiological culture and treatment.

Safety and efficacy of metformin in a restricted formulary

OBJECTIVE

To assess the efficacy and safety of metformin (MET) in the Veterans' Administration Northern California Health Care System during the period from June 1995 through April 1996 when its use required approval by Endocrinology.

STUDY DESIGN

A retrospective review of patient charts and computerized pharmacy and laboratory records. Patients served as their own historical controls.

PATIENTS AND METHODS

Patients receiving MET (n = 251) were identified from the pharmacy database. On-line laboratory data, including the intermediate outcome variable HbA1c, were retrieved by computer for the interval 4 months prior to the initial prescription to May 1996. Clinical data including weight and blood pressure were obtained from chart review.

RESULTS

Of 228 patients whose charts were available for review, 29 reported side effects, and 12 discontinued use due to these side effects. No patients were identified with lactic acidosis. Both baseline and treatment data on HbA1c were available on 164 patients. Mean HbA1c (%) data (unpaired), expressed as mean +/- SE, were as follows: between 4 months pretreatment and 1 month pretreatment, 9.41 +/- 0.19 (n = 103 tests); between 1 month pretreatment and baseline, 9.41 +/- 0.19 (n = 110 tests); 3 months of treatment, 8.79 +/- 0.16 (n = 157 tests, P < 0.05); 6 months of treatment, 8.30 +/- 0.17 (n = 79 tests, P < 0.0001); 9 months of treatment, 8.72 +/- 0.24 (n = 70 tests, P < 0.05), compared to pretreatment values. Similar analysis of unpaired weight and blood pressure data in 152 patients did not reveal any reduction in these clinical parameters over this treatment period. Serum lipids were unchanged on treatment (by paired analysis), but the number of tests was limited.

CONCLUSION

In this setting, MET provided sustained beneficial effects on glycemic control and was well tolerated. Any effects on weight, blood pressure, and serum lipids were not demonstrable in this analysis. We conclude that MET can substantially improve outcome of diabetes care.

Effects of sex hormones on mesangial cell proliferation and collagen synthesis

In a variety of renal diseases, males progress at a more rapid rate and have a more fulminant course than females. This gender difference may be related to the direct effects of sex hormones on the cells of the kidney. To evaluate this hypothesis, we studied the effects of estrogens and testosterone on mesangial cell proliferation and collagen synthesis. At 48 hours, estradiol at 10 nM and 100 nM had a modest proliferative effect on cultured mesangial cells, as measured by 3H thymidine incorporation into DNA and direct cell counting. This estradiol effect was fully reversed by Tamoxifen (1 microM). Estradiol had no effect on cellular proliferation at 1 microM concentrations, but suppressed proliferation at 10 microM doses. Testosterone had a modest but statistically insignificant effect on proliferation at 10 nM and 100 nM concentrations but no effect at 1 microM or 10 microM. Neither estradiol nor testosterone at 10 microM affected total cellular protein accumulation. Estradiol at 1 microM and 10 microM, markedly suppressed total collagen synthesis as measured by 3H proline incorporation, and specifically suppressed the synthesis of collagen types I and IV, as measured by immunoprecipitation and gel electrophoresis. Testosterone did not affect collagen synthesis. Estradiol also reduced the steady state message for the alpha 2 chain of type I collagen, while testosterone had no effect. Neither estradiol nor testosterone affected the steady state message for TGF beta or EGF. The direct effects of estradiol on mesangial cell collagen generation may help explain the slower development of glomerulosclerosis in women and therefore the "protective" effect of female gender on the progression of renal disease.