The respective roles of apoptosis and accidental cell death after thermal injury were evaluated in normal human epidermal keratinocytes. By coupling the LIVE/DEAD fluorescence viability assay with the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method and ultrastructural morphology , these two processes could be distin-

Thermal injury by short pulses (1-30 s) of relatively high temperature (50-68 degrees C) was investigated in normal human epidermal keratinocytes (NHEK). NHEK were cultured on plastic cover-slips and dipped in medium held at various temperatures. Survival assessed by methylthiazol tetrazolium reduction assay at 6 days postheating demonstrated an inverse time-temperature relationship that indicated that most cells could survive after a 1-s, 60 degrees C exposure or a 30-s, 55 degrees C exposure. Arrhenius plots of the data indicated major transition points for cell injury at 50 and 60 degrees C. Heat shock protein 70 (HSP70) and interleukin-8 (IL-8) were both induced by elevation of temperature between 50 and 60 degrees C for as short a time as 1 s. HSP70 synthesis stimulated by short, high pulses of heat appeared to induce thermotolerance. These results demonstrate that brief exposure to relatively high temperature can induce HSP70 and IL-8 synthesis in keratinocytes.

Little is known about the nutrition of the infants of the Fulani, migratory nomads of the western Sahel of Africa. Milk was collected from 18 Fulani women 10 to 30 days postpartum and the fatty acid compositions of the triacylglycerol and phospholipid fractions were determined by capillary gas-liquid chromatography. De novo fatty acids (10:0-14:0) comprised 36.3 +/- 12.7% of fatty acids of the triacylglycerols. Compared to the milk of various populations worldwide, the milk of the Fulani women contained adequate proportions of alpha-linolenic acid (0.50 +/- 0.16%) and arachidonic acid (0.42 +/- 0.22%), but relatively low amounts of linoleic acid (9.95 +/- 2.13%) and docosahexaenoic acid (DHA) (0.15 +/- 0.08%). In addition, the milk of the Fulani women contained adequate concentrations of beta-carotene (1.58 +/- 0.69 micrograms/dl) and vitamin A (42.7 +/- 40.3 micrograms/dl), but very low levels of vitamin E (0.11 +/- 0.10 mg/dl). These data indicate that exclusively breasted infants of Fulani women were receiving relatively low amounts of critical fatty acids and vitamin E.

In the eye, hydrolysis of stored retinyl esters is catalyzed by retinyl ester hydrolase (REH) activities in retinal pigment epithelium (RPE) membranes. In the present study, biochemical analyses were conducted to determine the substrate specificity of these activities. Specific activities determined for hydrolysis of various retinol isomers of retinyl palmitate (9-cis -, 11-cis -, 13-cis -, and all-trans -retinyl palmitates) indicated that 11-cis -retinyl palmitate is preferentially hydrolyzed (1.7 nmol/ min/mg) compared to the other isomers (0.1-0.3 nmol/ min/mg). Examination of the specificity of REH activity for 11-cis -retinyl esters of varied acyl chain length (-myristate, -palmitate, and -stearate) and degree of saturation (-oleate and -linoleate) further demonstrated that palmitate is the preferred fatty acyl moiety. Notably, retinyl esters possessing chain lengths which more closely approximate that of the palmitate ester exhibited higher rates of hydrolysis. Similar results were obtained in retinyl ester-plasma membrane fusion studies in which hydrolysis took place within the membrane domain rather than at the lipid-water interface. REH substrate specificity was further assessed in competition studies in which 11-cis -retinyl palmitate hydrolysis was monitored in the presence of 13-cis -, 9-cis -, or all-trans -retinyl palmitate. Results show that addition of these retinyl palmitate isomers does not affect the rate of hydrolysis of 11-cis -retinyl palmitate. However, the hydrolytic rates associated with other retinyl palmitate isomers were significantly reduced in the presence of 11-cis -retinyl palmitate. Finally, cholesterol ester hydrolase activity was found to be distinct from the observed 11-cis -REH activity and the presence of cholesterol oleate did not affect the rate of 11-cis -retinyl palmitate hydrolysis. Collectively, these data support the hypothesis that a distinct, membrane-associated, 11-cis -retinyl palmitate-specific retinyl ester hydrolase activity exists in the retinal pigment epithelium.-

No abstract