A role for endogenous arachidonate metabolites in the regulated expression of the 25-hydroxyvitamin D-1-hydroxylation reaction in cultured alveolar macrophages from patients with sarcoidosis.

In the human granulomatous disease sarcoidosis hypercalcemia and/or hypercalciuria result from the endogenous overproduction of 1,25-dihydroxyvitamin D [1,25-(OH)2D] by the disease-activated macrophage. Unlike the renal 25-hydroxy-vitamin D (25OHD)-1-hydroxylase, normally the sole synthetic source of the hormone in man, the 25OHD3-1-hydroxylation reaction in cultured pulmonary alveolar macrophages (PAM) from patients with sarcoidosis is subject to stimulation by the immune cytokine interferon-gamma (IFN gamma) and inhibition by the antiinflammatory glucocorticoid dexamethasone. The data presented here suggest that IFN gamma and calcium ionophore A23187 promote enhanced expression of the sarcoid PAM 25OHD3-1-hydroxylation reaction by increasing endogenous arachidonic acid metabolism through the 5-lipoxygenase pathway. Dexamethasone, an inhibitor of the cellular phospholipase-A2-arachidonic acid-generating system, and BW755C, a lipoxygenase pathway inhibitor, inhibited PAM 1,25-(OH)2D3 synthesis by 64% and 54%, respectively. Conversely, leukotriene C4, a distal metabolite in the arachidonic acid 5-lipoxygenase pathway, increased the hydroxylation reaction by 234% and restored dexamethasone-inhibited PAM 1,25-(OH)2D3 synthetic activity. The results of this study provide presumptive evidence for an important role of agonist (IFN gamma)-calcium-modulated eicosanoid metabolism in the regulated synthesis of 1,25-(OH)2D by PAM in sarcoidosis.

Ketoconazole decreases the serum 1,25-dihydroxyvitamin D and calcium concentration in sarcoidosis-associated hypercalcemia.

Ketoconazole is an antifungal agent capable of inhibiting human steroid hormone synthesis, including renal 1,25-dihydroxyvitamin D [1,25-(OH)2D] synthesis. The ability of this drug to inhibit the extrarenal production of 1,25-(OH)2D, as occurs in human granuloma-forming disease states, including sarcoidosis, has not been evaluated. We examined the effect of ketoconazole on the 1,25-(OH)2D-calcium homeostatic mechanism in a hypercalcemic patient with sarcoidosis and on the synthesis of 1,25-(OH)2D3 in vitro by cultured pulmonary alveolar macrophages (PAM) from this and another host. Oral ketoconazole therapy (800 mg/day) decreased the serum 1,25-(OH)2D concentration 73% within 4 days; this was associated with a 15% decrease in the serum calcium concentration and a 57% decrease in the fractional urinary calcium excretion rate. In vitro, ketoconazole had a rapid onset, concentration-dependent inhibitory effect on sarcoid PAM 1,25-(OH)2D3 synthesis (ED50 = 0.1 mumol/L) that was not reversible by exposure to leukotriene C4, a potent stimulator of PAM 1,25-(OH)2D3 synthesis. Kinetic analysis of ketoconazole's action on the macrophage 1 alpha-hydroxylation reaction was examined at concentrations achieved in vivo when the drug is given orally. The velocity of the 1 alpha-hydroxylation reaction at ketoconazole concentrations of 0.01-1.0 mumol/L increased as the concentration of substrate 25-hydroxyvitamin D3 increased from 12-2000 nmol/L.

Potentiation of the macrophage 25-hydroxyvitamin D-1-hydroxylation reaction by human tuberculous pleural effusion fluid.

1,25-Dihydroxyvitamin D [1,25-(OH)2D] is classically viewed as a steroid hormone of renal origin that regulates mammalian and avian mineral ion homeostasis. More recently, 1,25-(OH)2D has been shown to be produced by and act on human inflammatory cells in vitro, suggesting that the hormone may be an important modulator of the host immune response. We have recently detected high concentrations of 1,25-(OH)2D in the pleural fluid (PF) of patients with tuberculous pleuritis. Working on the hypothesis that tuberculous PF contained a soluble cytokine which stimulated 1,25-(OH)2D production by tissue (pleura)-based macrophages, we examined the potential for PF from five patients with tuberculous pleuritis to potentiate 1,25-(OH)2D synthesis by heterologous pulmonary alveolar macrophages (PAM) from patients with sarcoidosis; PAM from patients with active pulmonary sarcoidosis constitutively express a 25-hydroxyvitamin D3-1-hydroxylation reaction in vitro. We demonstrated that tuberculous PF had a concentration-dependent potentiating effect on PAM 1,25-(OH)2D synthesis. The potentiating activity was positively correlated to the interferon-gamma (IFN gamma) concentration of the PF (r = 0.98; P less than 0.01) and was inhibited by 49-89% after coincubation with anti-IFN gamma monoclonal antibody (1:20,000-1:200 dilution). These data suggest that IFN gamma may be an important peripleural regulator of macrophage 1,25-(OH)2D synthesis in patients with tuberculous pleuritis and a high pleural fluid 1,25-(OH)2D concentration.

Gender differences on a brief measure of cognitive functioning in Alzheimer's disease.

OBJECTIVE: We evaluated scores on a brief psychometric screening instrument--the Mini-Mental State Examination (MMSE)--for possible effects of gender, hypothesizing that women with Alzheimer's disease (AD) would perform more poorly than men. A significant gender difference was to be explored with post hoc item analyses. DESIGN: Case-study design. A hierarchical regression procedure controlled for the possible influence on MMSE performance of demographic variables (eg, age, duration of dementia symptoms, education, and family history of dementia) before the effect of gender was analyzed. SETTING: Data were gathered by trained neuropsychological examiners from subjects enrolled in the Alzheimer's Disease Research Center at the University of Southern California, Los Angeles. SUBJECTS: One hundred forty-two subjects who met strict criteria for probable AD and 121 nondemented elderly subjects were included in the study. All subjects underwent periodic neuropsychological testing. We extracted MMSE scores and demographic data to test the hypothesis that women would perform more poorly than men on the MMSE. CRITERION MEASURE: The MMSE was chosen because of its wide use in clinical and research settings to screen for the presence or severity of dementia. RESULTS: After controlling for the demographic variables for subjects with AD, we observed a significant difference in the predicted direction for total MMSE score, but there was no significant gender effect on the MMSE for the nondemented elderly sample. Among subjects with AD, gender-associated differences were limited to only a subset of MMSE items. CONCLUSIONS: Results imply that MMSE performance may differ between men and women with AD and that differences might pertain only to discrete areas of cognitive functioning. Although gender effects were relatively small, findings indicate the relevance of gender to studies of AD.

The agraphia of Alzheimer's disease.

Hypothesizing that agraphia in Alzheimer's disease (AD) reflects disturbances in multiple cognitive domains, we evaluated writing samples from 33 patients meeting strict criteria for probable AD. We found agraphia to be common on a standard narrative writing task. When compared with 41 education- and age-matched normal control subjects, AD patients had significantly lower writing scores, wrote significantly fewer words, mentioned significantly fewer categories of information, and were significantly more likely to make writing errors. On stepwise regression procedures, neuropsychological measures of visuoperceptual impairment and disease severity were the strongest predictors of agraphia, but other analyses indicated that measures of language, praxis, and attention could also contribute significantly to agraphia. On two writing tasks, we failed to confirm the previous contention that agraphia is a marker for familial AD. However, there was a highly significant interaction between family history, oral naming, and writing: patients with nonfamilial AD, but not those with a family history of dementia, showed a strong correlation between naming and writing performance. We conclude that agraphia in AD can be variously determined and that agraphia is not a reliable marker for familial disease.