Assessment of diaphragm function.

Assessment of diaphragm function begins with the physical examination, but neither the physical examination nor radiography is sensitive enough to detect subtle abnormalities of diaphragm function. Maximal static transdiaphragmatic pressure and maximal static inspiratory mouth pressure have been widely used as measures of diaphragm and inspiratory muscle strength, respectively. Both are useful as rough indications of muscle strength, but, because they are highly effort dependent, they should not be relied upon for absolute accuracy. Objective measurement of diaphragm function requires phrenic nerve stimulation.

Single, high-dose intramuscular triamcinolone acetonide versus weekly oral methotrexate in life-threatening asthma: a double-blind study.

Effective and less toxic treatments are needed for patients with severe, steroid-dependent asthma. Both low-dose oral methotrexate and high-dose intramuscular triamcinolone have been recommended for these patients. We compared the effects of these two medications on pulmonary function, peak flow rates, airway reactivity, oral steroid use, emergency room (ER) visits, and hospitalizations in patients with steroid-dependent, life-threatening asthma. In a randomized, placebo-controlled, double-blind study, we investigated 19 such patients. Six of the patients (Group I) received a single dose of 360 mg triamcinolone intramuscularly with placebo methotrexate; seven patients (Group II) received placebo triamcinolone followed by low-dose oral methotrexate (a first dose of 7.5 mg followed by 15 mg weekly); and six patients (Group III) received placebo triamcinolone with placebo methotrexate. All patients used the same high-dose inhaled steroids. The patients took tapering courses of oral steroids when needed, but attempted to reduce their oral steroid use whenever possible. Methacholine challenge testing was performed every 6 wk, pulmonary function tests every 4 wk, and home peak-flow measurements twice daily. Oral steroid use, ER visits, and hospitalizations were also monitored. The patients in the triamcinolone treatment group showed a significant and sustained increase in home peak-flow rates, and their FEV1 persistently improved by a mean of 40% (p < 0.05), whereas the FEV1 of the patients in the methotrexate treatment and placebo groups remained near baseline. The PC20 in the triamcinolone group increased progressively (p > 0.05), and the improvements in total mean reactivity were greater in this group than in either of the other two groups (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of human sebaceous cells in vitro.

Human sebaceous cells, isolated from adult human skin, were cultured on either bovine type I collagen or mitomycin-C-treated 3T3 fibroblasts. Sebaceous cells, termed "sebocytes", were determined to be epithelial in nature by positive staining with monoclonal antikeratin antibodies BG2 and BG12. However, sebocyte colonies were also negative for keratins found in differentiated cells of keratinocyte colonies, as defined by monoclonal antikeratin antibodies CC2 and CC6. Sebocytes did not produce cornified envelopes in vitro and could only be induced to produce small quantities (less than 5%) of envelopes with a calcium ionophore. Sebocyte growth characteristics in a variety of serum, dexamethasone, and hydrocortisone combinations were significantly different from those of human facial keratinocytes. Sebocytes also displayed a growth curve and plating efficiency that were different from those of keratinocytes. Large lipid droplets within growing sebocytes could be visualized with oil red o staining. Additionally, squalene and wax/cholesterol esters were made by sebocytes in vitro in greater amounts than by facial keratinocytes, as determined by thin-layer chromatography of organic extracts of 3H2O-labeled sebocytes. Sebocytes synthesized greater quantities of lipid, on a per-cell and protein basis, than did keratinocytes.

Cholate effects on all-trans-retinyl palmitate hydrolysis in tissue homogenates: solubilization of multiple kidney membrane hydrolases.

Retinyl ester hydrolysis was observed in the absence of cholate in homogenates of rat lung, liver, kidney, intestine, and testes. Eighty-four percent of the activity in kidney was membrane-associated. The kidney microsomal fraction contained 19% of the total activity and was the only subcellular fraction that had increased specific activity relative to the homogenate (about 1.5-fold). In contrast, the cytosol was the only fraction that was decreased in specific activity (about 3-fold). Cholate (18 mM), reportedly required to observe hydrolysis of all-trans-retinyl esters by rat liver preparations, was not obligatory for activity in kidney homogenates or microsomes. The microsomal activity was solubilized efficiently and with a twofold increase in specific activity by the synthetic detergent 1-S-octyl-beta-D-thioglucopyranoside. Gel-permeation chromatography of the solubilizate suggested that at least two pools of activity existed, with molecular weights in the ranges 70-95 and 30-40 kDa. Neither hydrolyzed cholesteryl oleate. Both were more active in hydrolyzing retinyl palmitate than trioleoylglycerol. The higher mass pool had decreased trioleoylglycerol hydrolase activity relative to the solubilizate. Anion-exchange chromatography separated the lower mass pool into two major peaks. A major peak, distinct from the two peaks observed with the lower mass pool, was observed upon anion-exchange chromatography of the higher mass pool. These data demonstrate that multiple retinyl ester hydrolases, more efficient at hydrolyzing retinyl esters than cholesteryl esters and triacylglycerol, occur in a retinoid target tissue.