Inhibition of Ca2+-dependent K+ channels by lead in one-step inside-out vesicles from human red cell membranes

Pb2+ modified the apparent threshold sensitivity to Ca2+ of individual K+ channels with a biphasic time-course. At first, the sensitivity to Ca2+ was lowered with the result of a decrease of the fraction of activated vesicles at a given Ca2+ concentration. Later, Pb2+ increased the sensitivity to Ca2+ and the fraction of activated vesicles. The increase of Pb2+ concentration increased the extent of the initial inhibition but decreased its duration. The inhibitory effect was not observed when the addition of Ca2+ preceded the addition of Pb2+. The presence of Mg2+ in the incubation medium was also required. In the absence of Mg2+, Pb2+ decreased the rate of uptake of 86Rb, but no decrease in the fraction of activated vesicles could be demonstrated.     

Effect of topically applied steroidal and nonsteroidal anti-inflammatory agents on skin repair and regeneration

We studied the effects of topically applied steroidal and nonsteroidal anti-inflammatory agents on dermal and epidermal wound healing. Superficial wounds (0.3 mm deep) on the skin of domestic pigs were treated daily with either 0.1% triamcinolone acetonide (TA), 1% hydrocortisone (HC), 1% nandrolone decanoate (ND), 1% ND + 0.1% TA, 10 mg ibuprofen, 10 mg meclofenamate sodium, 3 mg indomethacin, vehicle (USP petrolatum or 70% ethanol), or control (untreated). Wounds were excised on days 2-7 after wounding and the epidermis was separated from the dermis. The dermis was assayed for collagen biosynthesis and the epidermis was evaluated for reepithelialization. A significant decrease (P less than 0.01) in relative collagen synthesis was observed in the wounded dermis in both HC- and TA-treated groups on day 3 after wounding, but there were no significant differences on days 4-7. Depressed collagen and noncollagenous protein production was also noted in vehicle-treated wounds on day 3. Topical application of ND did not affect collagen synthesis, but when combined with TA it eliminated the inhibitory effect observed as a result of TA alone. Topical ND accelerated wound reepithelialization by 12.5% compared with vehicle and by 26% compared with untreated controls. TA delayed epidermal resurfacing by 22%, but when combined with ND (ND + TA) the rate of reepithelialization was similar to vehicle-treated wounds. HC enhanced resurfacing when compared with untreated wounds but did not differ markedly from its vehicle. The nonsteroidal anti-inflammatory drugs when topically applied markedly reduced inflammation (erythema, heat, and edema) but did not influence the healing process.     

Study of a madurella grisea strain isolated from a foot mycetoma

Madurella grisea has been isolated from a madura foot with black grains. The fungi classification was made based on the macro and micro-morphology characteristics of the culture. Difficulties with the interpretation of biochemistry tests were analized. The study is completed with trials of in vitro sensibility for different antifungic agents.     

Relationship of indole-3-butyric acid and adventitious rooting in M.26 apple (Malus Pumila mill.) shoots cultured in vitro

The role of indole-3-butyric acid (IBA) in adventitious root formation was studied by analyzing the uptake and subsequent metabolism of IBA in shoots of M.26 apple (Malus pumila Mill.) rootstock grown in vitro. Roots were induced by exposing shoots to 4 M IBA and [³H]IBA for 5 days in the dark and then transferring them to plant growth regulator (PGR)-free medium in the light until roots formed. Approximately 50% of the total radioactivity applied was taken up from the agar medium by the shoots during the 5-day incubation period in IBA. Indole-3-butyric acid metabolism was studied by extraction and high-performance liquid chromatographic (HPLC) separation of [³H]IBA and metabolites from the basal sections of treated shoots. The major [³H]IBA metabolite co-eluted with authentic [¹⁴C]indole-3-acetic acid (IAA) suggesting that IBA was converted to IAA in the shoots. The proportion of newly synthesized IAA present as conjugates was higher at the end of the 5-day IBA treatment period than after 13 days in PGR-free medium. There appeared to be no conjugation of IBA at any time.     

Isolation of peroxisomes from frozen human liver samples.

This paper shows the successful isolation of peroxisomes from human liver samples that were kept frozen at -70 degrees C. Purification of these peroxisomes was obtained by a combination of two subcellular fractionation techniques: differential centrifugation and isopycnic fractionation in Nycodenz density gradients. Peroxisome integrity was evaluated by latency measurements and by ultrastructural observation. The procedure described here may be useful for the isolation of other subcellular organelles from frozen human samples.     

The phytoplankton of some gravel-pit lakes in Spain

The phytoplankton communities of thirteen adjacent gravel-pit lakes in the lower Jarama river watershed (Madrid, Spain), were studied during spring mixing and summer stratification.If different seasons, the phytoplankton responded to different environmental factors. During spring, the abundance of SRP (soluble reactive phosphorus) and existence of a certain thermal stability resulted in the development of a greater biomass in some lakes. During summer, however, excessively high temperatures adversely affected the communities of the warmer lakes. At the species level, the responses were diverse; ordination techniques enabled us to group them.Some similarities were observed in phytoplankton composition between lakes, possibly due to local dispersion between adjacent lakes (frequented by abundant waterfowl).     

Molecular evolution of the N-formyl peptide and C5a receptors in non-human primates

N-formyl peptides (FMLP) and complement fragment C5a are neutrophil chemoattractants. In humans, a single-copy gene was identified for the C5a receptor, and the receptor for FMLP (FPR1) is encoded by a single gene that shows 53% amino acid similarity to the C5aR. Two other humanFPR1 homologues,FPR-like 1 (FPR2/FPRL1) andFPR-like 2 (FPRL2) have been cloned. The human C5aR, FPR1, FPRL1, and FPRL2 are physically linked. By direct sequencing or by sequencing plasmid clones we studied theC5aR andFPR genes from four non-human primates (chimpanzee, gorilla, orangutan, and macaque). The sequences showed 95%–99% similarity to the human homologues, with the major divergences observed in macaque. In these genes, the transmembrane and the cytoplasmic domains are highly conserved, while the highest divergence corresponded to the extracellular loops involved in ligand binding. Additionally, we constructed a physical map of these genes in non-human primates. In all species the four genes were physically linked and we defined the relative orientation of the four genes in primates:C5aR>FPR1>FPR2 (FPRL1)>FPRL2. The nucleotide sequence data reported in this paper have been submitted to the EMBL/GenBank nucleotide sequence databases and have assigned the accession numbers X97730 (PTC5aR), X97731 (MMC5aR), X97732 (PPC5aR), X97730 (GGC5aR), X97734 (MMFPR1), X97735 (PPFPR1), X97736 (GGFPR1), X97737 (MMFPRL1), X97738 (GGFPRL1), X97739 (PTFPRL1), X97740 (MMFPRL2), X97741 (PPFPRL2), X97742 (GGFPRL2), X97743 (PTFPRL2), X97744 (PPFPRL1), and X97745 (PTFPR1)     

Cloning and expression of the Neisseria meningitidis 5C outer membrane protein

The 5C outer membrane protein, one of the N. meningitidis class 5 proteins, was preferably expressed in bacteria isolated from the nasopharynx and its role in adhering to the mucosal cells and invading them as well as the development of anti-5C antibodies in healthy carriers was demonstrated. Anti-5C monoclonal antibodies are bactericidal in the presence of the human complement. The immunodominant region of the 5C protein is highly conserved among the different strains of N. meningitidis, and the opc gene, which encodes the protein, does not seem to show antigenic variations. Here the isolation of the opc gene from the Cuban strain B:4:P1.15 by PCR (Polymerase Chain Reaction) is presented. Under the regulation of the tryptophan promoter, the gene was cloned and sequenced in E. coli with a high level of expression and fused to the amino-terminal end of the interleukin-2 gene. In the dot-blot experiments, the presence of the gene in those strains which did not express the protein in the whole cell ELISA was also detectable.     

Phytoplankton strategies and time scales in a eutrophic reservoir

Phytoplankton species groups were studied in a eutrophic reservoir at different time scales (daily, weekly, monthly and yearly). Four strategic groups along the r-K continuum were defined and their seasonal time courses were followed. Their temporal distribution of relative biomass reflected resource partitioning because each strategic group dominated the phytoplankton community at different times in the year. However, the relationships between strategic groups changed with the time scale involved. At the daily scale an inverse relationship between r- and K-groups occurred whereas at supradaily scales such relationships did not hold. Species groups reflected strategic groups. No relationship between population growth and losses was found, suggesting that both were not counterbalanced. In the long term (supraannual) the phytoplankton community changed very much in this reservoir, its ecological memory being small as compared with that of lakes.