The importance of microscopic examination in the management of desquamative diseases of the scalp

After determining the usual malassezic biota of the scalp in adult, normal persons, 259 patients with different desquamative diseases were studied by a simple adhesive tape technique. The main purpose of this study was to investigate the utility of this technique to improve the diagnosis and treatment of patients. Most patients with seborrhoeic dermatitis and sebopsoriasis demonstrated large numbers of {it Malassezia} spp. cells corresponding to the so called ``pityrosporosis'. Only 43.6% of patients with pityriasis capitis (dandruff) presented with such a diagnosis. Symptomatic pityrosporosis of the scalp should be treated with imidazolic derivatives or other antifungal substances. Patients with psoriasis of the scalp showed a typical microscopic picture represented by parakeratosic (nucleated) keratinocytes with absence of lipophilic yeasts which should be attributed to the usual dryness of the scales .Microbial epidermitis (eczema) of the scalp revealed another characteristic picture constituted by abundant leukocytes and bacteria without the presence of yeasts. The different microscopic pictures seen with this simple technique for diseases of the scalp, offer an adjunct to make a proper diagnosis and to establish a convenient treatment in cases which are not clinically well defined. This revised version was published online in June 2006 with corrections to the Cover Date.     

Membrane topology of the acyl-lipid desaturase from Bacillus subtilis

The Bacillus subtilis acyl-lipid desaturase (Delta5-Des) is an iron-dependent integral membrane protein, able to selectively introduce double bonds into long chain fatty acids. Structural information on membrane-bound desaturases is still limited, and the present topological information is restricted to hydropathy plots or sequence comparison with the evolutionary related alkane hydroxylase. The topology of Delta5-Des was determined experimentally in Escherichia coli using a set of nine different fusions of N-terminal fragments of Delta5-Des with the reporter alkaline phosphatase (Delta5-Des-PhoA). The alkaline phosphatase activities of cells expressing the Delta5-Des-PhoA fusions, combined with site-directed mutagenesis of His residues identified in most desaturases, suggest that a tripartite motif of His essential for catalysis is located on the cytoplasmic phase of the membrane. These data, together with surface Lys biotinylation experiments, support a model for Delta5-Des as a polytopic membrane protein with six transmembrane- and one membrane-associated domain, which likely represents a substrate-binding motif. This study provides the first experimental evidence for the topology of a plasma membrane fatty acid desaturase. On the basis of our results and the presently available hydrophobicity profile of many acyl-lipid desaturases, we propose that these enzymes contain a new transmembrane domain that might play a critical role in the desaturation of fatty acids esterified in glycerolipids.     

Linkage mapping of Hsa-1<Superscript>Og</Superscript>, a resistance gene of African rice to the cyst nematode, <Emphasis Type="Italic">Heterodera sacchari</Emphasis>

Inheritance of resistance to cyst nematode (Heterodera sacchari) in Oryza sativa was investigated by inoculation tests with isolate 244 from Congo in segregating populations derived from hybridisation between O. sativa and its African sister cultivated species, O. glaberrima. We found that the resistance was controlled by one major gene, Hsa-1(Og), with codominance of susceptible and resistant alleles. To map Hsa-1(Og) on the rice genome, we pooled the data obtained from segregation of the resistance trait and microsatellite markers in three kinds of progeny: BC(1)F(3), BC(1)F(4), and pseudo-F(2) populations. Hsa-1(Og) was unambiguously located between Cornell University's RM206 and RM254 markers on chromosome 11. Two additional microsatellite markers derived from Monsanto publicly available sequences were found to be tightly linked to the Hsa-1(Og) gene. It is possible that numerous plant resistances to a pathogen in fact exhibit a codominant inheritance, possibly explaining misleading conclusions in several reports on resistance segregation.     

TIMP-2 mediated inhibition of angiogenesis: an MMP-independent mechanism

Tissue inhibitors of metalloproteinases (TIMPs) suppress matrix metalloproteinase (MMP) activity critical for extracellular matrix turnover associated with both physiologic and pathologic tissue remodeling. We demonstrate here that TIMP-2 abrogates angiogenic factor-induced endothelial cell proliferation in vitro and angiogenesis in vivo independent of MMP inhibition. These effects require alpha 3 beta 1 integrin-mediated binding of TIMP-2 to endothelial cells. Further, TIMP-2 induces a decrease in total protein tyrosine phosphatase (PTP) activity associated with beta1 integrin subunits as well as dissociation of the phosphatase SHP-1 from beta1. TIMP-2 treatment also results in a concomitant increase in PTP activity associated with tyrosine kinase receptors FGFR-1 and KDR. Our findings establish an unexpected, MMP-independent mechanism for TIMP-2 inhibition of endothelial cell proliferation in vitro and reveal an important component of the antiangiogenic effect of TIMP2 in vivo.     

High-performance thin-layer chromatography-bioautography for multiple antibiotic residues in cow's milk

An analytical method to identify and quantify multiple antibiotic residues (chloramphenicol, ampicillin, benzylpenicillin, dicloxacillin and erythromycin) in cow's milk by high-performance thin-layer chromatography (HPTLC) combined with bioautography was developed. The test microorganism used for bioautography was Bacillus subtilis ATCC 6633. Antibiotic residues were extracted with acetonitrile, fat eliminated with petroleum ether and residues isolated with dichloromethane The sensitivity of the method guarantees the detection of the above-mentioned antibiotics at levels below maximum residue limits (MRL) allowed for milk. Percentage recoveries ranged between 90 and 100%, with coefficients of variation between 7.2 and 21.3%. Some advantages of this methodology over thin-layer chromatography (TLC)/bioautography are also discussed.     

Determination of chloramphenicol residues in shrimps by liquid chromatography-mass spectrometry

A liquid chromatographic method with mass spectrometric detection and identification (LC-MS) is presented for the determination of chloramphenicol (CAP) in shrimp tissues. Homogenized shrimp samples were extracted with phosphate buffer (pH 7.0). Clean-up was carried out on a C(18) SPE cartridge. Chloramphenicol was determined by LC-MS-ESI in negative mode. The column used was a Symmetry Shield with a mixture of acetonitrile-water (25:75) as mobile phase. Shrimp samples were fortified at CAP levels between 0.2 and 50 ng g(-1) with 5D-CAP as internal standard. At these levels, accuracies lay between 101 and 110% and between-day reproducibilities were lower than 7.1%, expressed as the variation coefficient of the mean. Limit of decision (CCalpha) was 0.02 ng g(-1). Limit of quantitation (LOQ) was 0.2 ng g(-1).     

Characterization of a Paenibacillus cell-associated xylanase with high activity on aryl-xylosides: a new subclass of family 10 xylanases

The sequence of gene xynB encoding xylanase B from Paenibacillus sp. BP-23 was determined. It revealed an open reading frame of 999 nucleotides encoding a protein of 38,561 Da. The deduced amino acid sequence of xylanase B shows that the N-terminal region of the enzyme lacks the features of a signal peptide. When the xylan-degrading system of Paenibacillus sp. BP-23 was analysed in zymograms, it revealed that xylanase B was not secreted to the extracellular medium but instead remained cell-associated, even in late stationary-phase cultures. When xynB was expressed in a Bacillus subtilis secreting host, it also remained associated with the cells. Sequence homology analysis showed that xylanase B from Paenibacillus sp. BP-23 belongs to family 10 glycosyl hydrolases, exhibiting a distinctive high homology to six xylanases of this family. The homologous enzymes were also found to be devoid of a signal peptide and seem to constitute, together with xylanase B, a separate group of enzymes. They all have two conserved amino acid regions not found in the other family 10 xylanases, and cluster in a separate group after dendrogram analysis. We propose that these enzymes constitute a new subclass of family 10 xylanases, that are cell-associated, and that hydrolyse the xylooligosaccharides resulting from extracellular xylan hydrolysis. Xylanase B shows similar specific activity on aryl-xylosides and xylans. This can be correlated to some, not yet identified, trait of catalytic activity of the enzyme on plant xylan.     

Different blocking effects of HgCl2 and NaCl on aquaporins of pepper plants

In this study we have compared the short-term effects of both NaCl and HgCl₂ on aquaporins of Capsicum annuum L. plants, in order to determine whether or not they are similar. Stomatal conductance, turgor, root hydraulic conductance and water status were measured after 0.5, 2, 4 and 6 h of NaCl (60 mmol/L) or HgCl₂ (50 μmol/L) treatment. When 60 mmol/L NaCl was added to the nutrient solution, a large decrease in stomatal conductance was observed after 2 h. However, when HgCl₂ (50 μmol/L) was added, the decrease occurred after 4 h. The number of open stomata closed was always lower in plants treated with HgCl₂ than in plants treated with NaCl. The water content of the Hg²⁺-treated plants was decreased, compared with controls and NaCl-treated. The root hydraulic conductance decreased after HgCl₂ and NaCl treatment plants. Turgor of leaf epidermal cells was greatly reduced in plants treated with HgCl₂, but remained constant in the NaCl treatment, compared with control plants. The fact that the stomatal conductance was reduced more rapidly after NaCl addition, followed by the stomatal closure, and that both water content and turgor did not differ from the control suggests that in NaCl-treated plants there must be a signal moving from root to shoot. Therefore, the control of plant homeostasis through a combined regulation of root and stomatal exchanges may be dependent on aquaporin regulation.     

Baclofen reestablishes striatal and cortical dopamine concentrations during naloxone-precipitated withdrawal

The present study analyzes the effects of baclofen (BAC) on mice brain neurochemical alterations during the morphine (MOR) withdrawal syndrome. Male Swiss-Webster albino mice (27-33 g) were rendered dependent by intraperitoneal (i.p.) injection of MOR (2mg/kg), twice daily for 9 days. On day 10, the dependent animals were divided into two groups: one receiving naloxone (NAL; 6 mg/kg i.p.) to precipitate the withdrawal syndrome 60 min after the last dose of MOR and the other received BAC (2mg/kg, i.p.) followed by NAL (6 mg/kg, i.p.), injected 30 and 60 min after the last dose of MOR, respectively. Ten minutes after these treatments, mice were killed by decapitation and the striatum, cortex and hippocampus were dissected to determine endogenous concentrations of dopamine (DA), 5-hydroxytryptamine (5-HT) and their metabolites using HPLC with electrochemical detection. Striatal DA, dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA) concentrations as well as cortical DA concentrations of the withdrawal groups decreased significantly with respect to the control groups. BAC attenuated the decrease in DA and DOPAC concentrations observed during the withdrawal, without modifying per se the control DA concentrations. No changes on 5-HT and its metabolite 5-hydroxyindolacetic acid (5-HIAA) concentrations were observed during the MOR abstinence syndrome. The prevention caused by BAC on the decreased concentrations of DA induced by MOR withdrawal could have a therapeutic interest for the management of withdrawal syndrome.