[Emergence of Microsporum audouinii and Trichophyton tonsurans as causative organisms of tinea capitis in the Dominican Republic]. / Tinea capitis. Emergencia de Microsporum audouinii y Trichophyton tonsurans en la República Dominicana.

BACKGROUND: Tinea capitis affects mainly children. The frequency and causative organism vary from region to region. OBJECTIVES: To provide epidemiological and mycological data on tinea capitis collected in urban and rural areas of the Dominican Republic. METHODS: Samples were obtained from 118 patients with tinea capitis. Sixty-three of these were from 2 schools in urban areas of the Dominican capital Santo Domingo (53%) and 55 were from rural schools on the border with Haiti (47%). RESULTS: The study included 84 boys (71. 18%) and 34 girls (28. 81%). The urban sample comprised mainly boys (84. 12%). The most represented age ranges were 6 to 8 years (47. 45%), 3 to 5 years (24. 59%), and 9 to 11 years (16. 94%). Microsporum audouinii (39. 68%), Trichophyton tonsurans (23. 80%), Microsporum canis (19. 04%), and Trichophyton violaceum (1. 58%) were isolated from children in urban areas, whereas T. tonsurans (87%) and Trichophyton mentagrophytes (2%) were isolated from those in rural areas. Overall, T. tonsurans (61. 16%), M. audouinii (24. 27%), and M canis (11. 65%) were the most frequently isolated causative organisms, whereas T. violaceum and T. mentagrophytes were rarely reported. CONCLUSIONS: In urban areas of the Dominican Republic, tinea capitis was found mainly in boys, but in rural areas it was evenly distributed among boys and girls. The emergence of M. audouinii and an increase in T. tonsurans were found while M. canis continued to be present at lower frequencies. On the rural border with Haiti, there was a significant predominance of T. tonsurans.

Differential efficacy of lipophilic and cytosolic antioxidants on generation of reactive oxygen species by amyloid-beta.

Exposure of neurons to amyloid-beta (Abeta) is accompanied by a cascade of oxidative damage that initiates with lipid peroxidation followed by subsequent generation of cytosolic free radicals and reactive oxygen species (ROS). The antioxidant vitamin E has been utilized to counteract Abeta-induced oxidative stress. We considered herein whether or not the lipid-solubility of vitamin E limits its neuroprotection to membrane-related oxidative damage, and renders it relatively ineffective where prior lipid peroxidation has already generated cytosolic free radicals and ROS. To test this possibility, we treated differentiated SH-SY-5Y human neuroblastoma with vitamin E or a cell-permeant antioxidant, N-acetyl cysteine (NAC), simultaneously with or 15 min after the application of Abeta. Both vitamin E and NAC prevented Abeta-induced ROS generation when applied simultaneously with Abeta, but only NAC prevented Abeta-induced ROS generation when added to cultures that had previously been exposed to Abeta. These results support the hypothesis that vitamin E can quench Abeta-induced lipid peroxidation, but cannot effectively quench ROS generated by prior lipid peroxidation. These findings in cell culture may provide limited insight into why vitamin E is not fully effective against neurodegeneration in AD in clinical settings, since some neuronal populations are likely to already have been compromised by prior Abeta exposure before vitamin E treatment was initiated.

Differential efficacy of lipophilic and cytosolic antioxidants on generation of reactive oxygen species by amyloid-ß.

Exposure of neurons to amyloid-beta (Abeta) is accompanied by a cascade of oxidative damage that initiates with lipid peroxidation followed by subsequent generation of cytosolic free radicals and reactive oxygen species (ROS). The antioxidant vitamin E has been utilized to counteract Abeta-induced oxidative stress. We considered herein whether or not the lipid-solubility of vitamin E limits its neuroprotection to membrane-related oxidative damage, and renders it relatively ineffective where prior lipid peroxidation has already generated cytosolic free radicals and ROS. To test this possibility, we treated differentiated SH-SY-5Y human neuroblastoma with vitamin E or a cell-permeant antioxidant, N-acetyl cysteine (NAC), simultaneously with or 15 min after the application of Abeta. Both vitamin E and NAC prevented Abeta-induced ROS generation when applied simultaneously with Abeta, but only NAC prevented Abeta-induced ROS generation when added to cultures that had previously been exposed to Abeta. These results support the hypothesis that vitamin E can quench Abeta-induced lipid peroxidation, but cannot effectively quench ROS generated by prior lipid peroxidation. These findings in cell culture may provide limited insight into why vitamin E is not fully effective against neurodegeneration in AD in clinical settings, since some neuronal populations are likely to already have been compromised by prior Abeta exposure before vitamin E treatment was initiated.

Teratogenic assessment of four solvents using the Frog Embryo Teratogenesis Assay--Xenopus (FETAX).

The Frog Embryo Teratogenesis Assay--Xenopus (FETAX) was used to assess the teratogenic potential of four solvents. Embryos of the South African clawed frog, Xenopus laevis, were exposed for 96 h to ethanol, dimethyl sulfoxide (DMSO), formamide or glycerol formal. Exposure groups were maintained using a static renewal system in which the exposure media were changed at 24-h intervals. Survival was monitored at 24-h intervals. Length, as an indicator of growth effects, and developmental malformations were determined at the end of the assay (96 h). Using this information, the 96-h LC50, the 96-h EC50 (Malformation), and the no observable effect levels (NOELs) for mortality, malformation and length were determined for each solvent. The teratogenic index [TI = 96-h LC50/96-h EC50 (Malformation)] also was calculated for each of the solvents. DMSO appeared to be the least toxic or teratogenic solvent examined, with a pooled LC50 of 1.92%, a pooled EC50 (Malformation) of 1.57% and TI values of 1.20 and 1.24 in replicate trials. Formamide appeared to be the most toxic solvent, with a pooled LC50 of 1.04%. Data trends suggested that ethanol was the most teratogenic solvent tested, with a pooled EC50 (Malformation) of 1.04% and TI values of 1.42 and 1.50. The results obtained in the present work for ethanol and DMSO were compared to previously published FETAX results for these two solvents. The present results are in close agreement with these results from other laboratories, thus providing further evidence supporting the interlaboratory reproducibility of FETAX results.

Arthropathy and cutaneous calcinosis in hemodialysis oxalosis.

Recently, calcium oxalate crystals have been identified in the synovial fluid of patients with arthritis and end-stage renal failure. We describe 4 patients who, during the course of long-term hemodialysis, developed calcium oxalate crystal deposits in the synovium and skin. Clinical manifestations included podagra, tenosynovitis, olecranon bursitis, and acute and chronic synovitis of the large joints that were associated with chondrocalcinosis or subchondral bone erosions. Diffuse involvement of the hand, with chondrocalcinosis of the finger joints, miliary calcified deposits in the skin, and artery calcifications, was observed in 3 patients. The fourth patient had erosive arthropathy. Oxalosis secondary to end-stage renal failure in patients treated with long-term hemodialysis can present with articular manifestations that resemble those of gout, pseudogout, and apatite deposition disease. Other characteristic features of the synovitis associated with oxalosis secondary to end-stage renal disease were: predominant involvement of the hand, mild inflammatory changes in the synovial fluid and synovium, and poor response to administration of nonsteroidal antiinflammatory agents.

Ultrastructure and cytochemistry of glycogen-containing vacuoles in gastrodermal cells in developing hydranths of a hydromedusan coelenterate.

Hydranth buds from the colonial hydroid Sertularia pumila (Hydromedusae) were observed by electron microscopy during their development. Before hydranth expansion, the gastrodermal columnar digestive cells had large numbers of vacuoles. These vacuoles contained many membranous components as well as alpha-glycogen and dense ring- and crescent-shaped bodies. The rings and crescents were not osmiophilic, but did react to periodic acid oxidation in the PA-TSC-SP test for carbohydrate. These structures were digestible by alpha-amylase and pullulanase. The chemical analyses and the close association of the rings and crescents to alpha-glycogen particles showed that they may be a highly condensed form of glycogen. Golgi bodies in association with the gastrodermal vacuoles had acid phosphatase activity. This enzyme was only slightly active in the vacuoles. It is suggested that the vacuoles are primarily storage organelles with a potential for digestion.

Scanning electron microscope studies of anesthetized Tricula aperta, vector of mekong Schistosoma.

Nembutal, menthol, Ketaset, and Curarine were used to anesthetize beta race of Tricula aperta snails in preparation for study by scanning electron microscopy. The snails remained sensitive to the glutaraldehyde fixative in low level anesthesia of nembutal, menthol and Ketaset. Snails were also sensitive to Curarine and retracted into their shells. The best relaxations were obtained by initial anesthesia with nembutal or menthol followed by curarine. Snails relaxed by this procedure showed relatively little reaction to the fixative solution and remained extended outside their shells. The surface ultrastructure of the snails was well preserved, showing microvillate, secretory, and ciliated sensory cells. The mucoid secretions remained on the surface of cilia on the body and foot of the snails as spherical granules. There were two types of ciliated cells: (1) Those with few short cilia showing 1-3 microns above the microvilli of surrounding cells and (2) Those with numerous cilia up to 10 microns long. Results of transmission electron microscopic studies of these snails show no disruption of the ultrastructure of the surface cells.

An ultrastructural study of the development of the dermal iridophores and structural pigmentation in Poecilia reticulata (peters).

Three general stages of iridophore development were found in Poecilia reticulata that correspond to the development of structural pigmentation. The first stage was prevalent in fish embryos about to hatch to young fish 4 months old. Dermal cells containing elements of endoplasmic reticulum and a Golgi apparatus developed into iridophores. The endoplasmic reticulum early in iridophore development became a few sparse cisternae, and the Golgi apparatus elaborated long rectangular vacuoles with two membranes. From 5 to 15 vacuoles were arranged in parallel stacks in each developing iridophore. Crystals of guanine were deposited within the inner compartment of each vacuole. At this stage of development, the young fish had only a few dermal iridophores next to the lateral muscle. Fish 4 to 6 months old had a more advanced type of iridophore development including several layers of iridophore cells in the dermis. The innermost iridophores near the muscle had many mature crystal-containing vacuoles (iridosomes). Each cell had upt to three stacks of 10-20 iridosomes with their long axis oriented at a slight oblique angle to the surface of the fish. The outer layers of iridophores resembled the immature developing cells found in very young fish. The third developmental stage was found in sexually functional adults. All dermal iridophores contained 2-3 groups of 10-20 mature iridosomes. In mature iridophores, the Golgi apparatus was not found in the cytoplasm. The thickness of the guanine crystals (70 nm) and cytoplasmic intervals (90 nm) results in a constructive interference reflection of 496 nm (blue-green). This iridescence increased concomitantly with the increase in iridophore cells in the dermis and the maturation of their iridosomes.

Crystal morphology and carbon/carbon composition of solid oxalate in cacti.

Morphology, crystal structure, and carbon isotopic composition of calcium oxalate from representative species from the family Cactaceae were determined using scanning electron microscopy, x-ray diffraction, and isotope ratio mass spectrometry. Crystals from one species in the Opuntieae tribe of the Cactaceae were druses with acute points composed of the monohydrate form of calcium oxalate (whewellite). Crystals from three species in the Cereeae tribe were the dihydrate form of calcium oxalate (weddellite) forming druses made up of tetragonal and isodiametric crystallites. The oxalate was relatively enriched in (13)C isotope (-7.3 to - 8.7 per thousand) compared with woody fibers (-13.3 to 14.1 per thousand) from the same plants.

Mechanism of suckling-rat hypercholesteremia. II. Cholesterol biosynthesis and cholic acid turnover studies.

Cholesterol biosynthesis from acetate-2-(14)C by the livers of suckling rats, which is known to be relatively slow, was increased 2-3-fold within 24 hours after severing the bile duct. Cholesterol synthesis by sham-operated litter mates showed no change under similar treatment. Mevalonate biosynthesis from acetate-2-(14)C in vitro by recombined liver microsomal supernatant (105,000xg) fractions from suckling rats also was only 10% of that of comparable recombined fractions from normal controls (young adult rats which were consuming colony diet). Activity was not improved by combining either the microsomal or supernatant fraction from suckling rat livers with the complementary fraction from normal adult livers. On the other hand, activity was restored to 100% when microsomes from livers of duct-served suckling rats were combined with the supernatant fraction from normal controls. Likewise, recombined liver fractions prepared from adult rats fed synthetic diets exhibited low activity for mevalonate biosynthesis. Activity was restored by bile duct cannulation, but inhibited when cholic acid was infused into the cannulated animal. Therefore, surgical procedures which interrupt the enterohepatic recirculation of bile components lead to a restoration of cholesterol biosynthesis and, at least in the adult animal where cannulation studies are practicable, this effect can be reversed readily by bile acid infusion.A slow rate of fecal excretion of(14)C-cholic acid was observed in suckling rats and rats fed synthetic diets, apparently reflecting an efficient enterohepatic recirculation of bile salts. The data suggest that under these dietary conditions bile salt retention either directly or indirectly influences hepatic synthesis of cholesterol.