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BACKGROUND: Laser resurfacing procedures are continuing to grow in popularity as patients select less invasive procedures for rejuvenation of photo-damaged and aging skin. However, although physicians have begun exploring options to aid in postlaser healing, currently available treatments have little clinical evidence to support their use for wounded skin. METHODS: When grown under conditions of very low oxygen and suspension, a simulation of the embryonic environment, neonatal cells have been found to produce proteins and growth factors in types and quantities similar to those of fetal cells. The human cell-conditioned media (hCCM) produced by the cells was extracted and formulated into a gel to evaluate its efficacy in the healing of postlaser wounds. RESULTS: A split-face clinical evaluation of the material was performed, with 42 subjects undergoing combination ablative and nonablative laser procedures. Three concentrations of the hCCM were tested (× 0.1, × 1.0, × 10.0), and a dose-response trend was seen in the blinded physician evaluation, particularly in the assessment of crusting. In addition, transepidermal water loss readings showed a significant difference (p ≤ 0.05), indicating a more rapid return to normal skin barrier function with the active treatment. Histopathologic evaluation of subject biopsies showed reduced inflammation and a more normal epidermal appearance in the active treatment sites. CONCLUSIONS: The results of this clinical evaluation support the use of the soluble hCCM produced under embryonic-like conditions to accelerate wound healing after laser resurfacing procedures. The utility of the × 10 concentration appears to promote more rapid, scarless wound healing after resurfacing procedures and more normal skin recovery.

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We report the use of the bacteriophage P1 Cre-lox system for generating conservative site-specific recombination between tobacco chromosomes. Two constructs, one containing a promoterless hygromycin-resistance gene preceded by a lox site (lox-hpt) and the other containing a cauliflower mosaic virus 35S promoter linked to a lox sequence and the cre coding region (35S-lox-cre), were introduced separately into tobacco plants. Crosses between plants harboring either construct produced plants with the two constructs situated on different chromosomes. Plants with recombination events were identified by selecting for hygromycin resistance, a phenotype expressed upon recombination. Molecular analysis showed that these recombination events occurred specifically at the lox sites and resulted in the reciprocal exchange of flanking host DNA. Progenies of these plants showed 67-100% cotransmission of the new transgenes, 35S-lox-hpt and lox-cre, consistent with the preferential cosegregation of translocated chromosomes. These results illustrate that site-specific recombination systems can be useful tools for the large-scale manipulation of eukaryotic chromosomes in vivo.

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M13 DNA fingerprinting was used to determine evolutionary changes that occurred in Latin American germ plasm and USA cultivars of commonbean (Phaseolus vulgaris L.) during domestication. Linkage mapping experiments showed that M13-related sequences in the common-bean genome were either located at the distal ends of linkage groups or that they were unlinked to each other or to any previously mapped markers. Levels of polymorphism observed by hybridization with M13 (1 probe-enzyme combination) were comparable to those observed by hybridization with single-copy random PstI genomic probes (36 enzyme-probe combinations) but were higher than those observed for isozymes (10 loci). Results indicated that the wild ancestor had diverged into two taxa, one distributed in Middle America (Mexico, Central America, and Colombia) and the other in the Andes (Peru and Argentina); they also suggested separate domestications in the two areas leading to two cultivated gene pools. Domestication in both areas led to pronounced reductions in diversity in cultivated descendants in Middle America and the Andes. The marked lack of polymorphism within commercial classes of USA cultivars suggests that the dispersal of cultivars from the centers of origin and subsequent breeding of improved cultivars led to high levels of genetic uniformity. To our knowledge, this is the first crop for which this reduction in diversity has been documented with a single type of marker in lineages that span the evolution between wild ancestor and advanced cultivars.

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An awareness of pigmentary nuances and an understanding of the psychosocial impact of pigmentary disturbances in blacks is essential in rendering optimal dermatologic care to black patients.

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The purpose of our investigation was to quantitatively assess T cell profiles in vitiligo and to correlate any aberrations in these findings with the spectrum of clinical disease. Twenty randomly selected vitiligo patients and sixteen healthy matched control subjects were studied. The immunofluorescence and complement-mediated cytotoxicity assays were used to determine the percentages of total T (OKT3), helper (OKT4), and suppressor (OKT8) cells in the peripheral blood of patients and controls. Both assays gave comparable results. Patients with vitiligo had a statistically significant decrease in helper cells and helper/suppressor ratios in comparison with control subjects (p less than 0.01). In addition, there was a statistically significant decrease in helper cells among patients with a disease duration of less than 1 year (p less than 0.01) and in patients who produced serum autoantibodies (p less than 0.05). These findings tend to suggest that aberrations in cell-mediated immunity may be operative in the pathogenesis of vitiligo.

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