Molecular identification and antifungal susceptibility profiles of etiologic agents of oral candidiasis among HIV-positive patients: A multicenter study

Background and Purpose

Human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) is a serious risk factor for oral candidiasis (OC). In this regard, the present study aimed to investigate the frequency of Candida species collected from the oropharyngeal cavity of HIV-positive patients and the sensitivity of these isolates to antifungal drugs.

Materials and Methods

Oral samples were collected from 169 HIV-positive patients. In addition to culture-based methods, a molecular assay via the polymerase chain reaction-restriction fragment length polymorphism method was applied to identify isolates using the MspI restriction enzyme. The disk diffusion method determined the susceptibility of isolated yeasts to common antifungal drugs according to the CLSI M44-A2 protocol.

Results

In total, 81 participants (47.92%) were positive for OC, and Candida albicans was the most prevalent yeast (53.98%). The median age of patients was 36 years old (IQR=10.5; 17-59), and it was found that women are 27% more susceptible to HIV-associated OC (OR=1.268; 95% CI: 0.685-2.348). Patients who received antifungal therapy had a 97.3% reduced chance for OC (OR: 0.027; 95% CI: 0.008-0.091; P-value: 0.000). Antifungal therapy reduced the risk of OC by 97.3% (OR=0.027; 95% CI=0.008-0.091; P=0.000), and antiretroviral therapy decreased the chance of OC 4.42 times (OR=4.423; 95% CI=1.697-11.528; P=0.002). The resistance rates for antifungals, namely fluconazole, ketoconazole, itraconazole, amphotericin B, and nystatin were 15.93%, 8.85%, 7.96%, 5.31%, and 4.42%, respectively.

Conclusion

Although several decades have passed since the emergence of HIV/AIDS, little information is available about fungal colonization and infections in this population. Further investigations are suggested using novel and reference molecular identification methods, such as matrix-assisted laser desorption ionization time-of-flight mass spectrometry and sequencing, respectively. In addition, more reliable methods for antifungal susceptibility testing are recommended.

An examination of maximum legal application rates of dairy processing and associated STRUBIAS fertilising products in agriculture

The dairy industry produces vast quantities of dairy processing sludge (DPS), which can be processed further to develop second generation products such as struvite, biochars and ashes (collectively known as STRUBIAS). These bio-based fertilizers have heterogeneous nutrient and metal contents, resulting in a range of possible application rates. To avoid nutrient losses to water or bioaccumulation of metals in soil or crops, it is important that rates applied to land are safe and adhere to the maximum legal application rates similar to inorganic fertilizers. This study collected and analysed nutrient and metal content of all major DPS (n = 84) and DPS-derived STRUBIAS products (n = 10), and created an application calculator in MS Excel™ to provide guidance on maximum legal application rates for ryegrass and spring wheat across plant available phosphorus (P) deficient soil to P-excess soil. The sample analysis showed that raw DPS and DPS-derived STRUBIAS have high P contents ranging from 10.1 to 122 g kg^-1. Nitrogen (N) in DPS was high, whereas N concentrations decreased in thermo-chemical STRUBIAS products (chars and ash) due to the high temperatures used in their formation. The heavy metal content of DPS and DPS-derived STRUBIAS was significantly lower than the EU imposed limits. Using the calculator, application rates of DPS and DPS-derived STRUBIAS materials (dry weight) ranged from 0 to 4.0 tonnes ha^-1 y^-1 for ryegrass and 0-4.5 tonnes ha^-1 y^-1 for spring wheat. The estimated heavy metal ingestion to soil annually by the application of the DPS and DPS-derived STRUBIAS products was lower than the EU guideline on soil metal accumulation. The calculator is adaptable for any bio-based fertilizer, soil and crop type, and future work should continue to characterise and incorporate new DPS and DPS-derived STRUBIAS products into the database presented in this paper. In addition, safe application rates pertaining to other regulated pollutants or emerging contaminants that may be identified in these products should be included. The fertilizer replacement value of these products, taken from long-term field studies, should be factored into application rates.

Utilisation of bis-chloroacetamide derivative in the synthesis of new biologically active sulfide compounds

4-Aminobenzohydrazide (1) undergoes chloroacetylation twice, at the primary amine and hydrazide-NH2 functional groups. The conforming bis-chloroacetamide derivative 3 was reacted with different sulfur reagents (namely, 2-mercaptobenzothiazole, 6-amino-2-mercaptopyrimidin-4-ol, and 2-mercapto-4,6-dimethyl-nicotinonitrile) to give new bis-sulfide compounds 5, 7 and 9, respectively. The newly synthesised bis-chloroacetamide and corresponding sulfides were screened for anti-microbial and antioxidant potential. The sulfide derivative 7 exhibited the most potent activity against Staphylococcus aureus and Pseudomonas aeruginosa. It shows inhibition activities of 83.4% and 78.8%, respectively. Moreover, the sulfide derivative 7 showed the highest antioxidant activity with an inhibition ratio of 85.9%, which is close to L-ascorbic acid.

Suitable Signal Peptides for Secretory Production of Recombinant Granulocyte Colony Stimulating Factor in Escherichia coli

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) expressed in engineered Escherichia coli (E. coli) as a recombinant protein is utilized as an adjunct to chemotherapy for improving neutropenia. Recombinant proteins overexpression may lead to the creation of inclusion bodies whose recovery is a tedious and costly process. To overcome the problem of inclusion bodies, secretory production might be used. To achieve a mature secretory protein product, suitable signal peptide (SP) selection is a vital step.

OBJECTIVE

In the present study, we aimed at in silico evaluation of proper SPs for secretory production of recombinant G-CSF in E. coli.

METHODS

Signal peptide website and UniProt were used to collect the SPs and G-CSF sequences. Then, SignalP were utilized in order to predict the SPs and location of their cleavage site. Physicochemical features and solubility were investigated by ProtParam and Protein-sol tools. Fusion proteins sub-cellular localization was predicted by ProtCompB.

RESULTS

LPP, ELBP, TSH, HST3, ELBH, AIDA and PET were excluded according to SignalP. The highest aliphatic index belonged to OMPC, TORT and THIB and PPA. Also, the highest GRAVY belonged to OMPC, ELAP, TORT, BLAT, THIB, and PSPE. Furthermore, G-CSF fused with all SPs were predicted as soluble fusion proteins except three SPs. Finally, we found OMPT, OMPF, PHOE, LAMB, SAT, and OMPP can translocate G-CSF into extracellular space.

CONCLUSION

Six SPs were suitable for translocating G-CSF into the extracellular media. Although growing data indicate that the bioinformatics approaches can improve the precision and accuracy of studies, further experimental investigations and recent patents explaining several inventions associated to the clinical aspects of SPs for secretory production of recombinant GCSF in E. coli are required for final validation.

RANTES gene polymorphisms (-403G>A and -28C>G) associated with hepatitis B virus infection in a Saudi population

Besides the host immune response, genetic and environmental factors play crucial roles in the manifestation of hepatitis B virus (HBV) infection. "Regulated on activation normal T-cell expressed and secreted" factor (RANTES) plays a vital role in CD4(+), CD8(+) T-lymphocyte and dendritic cell activation and proliferation in inflammation. Single nucleotide polymorphisms (SNPs) in the RANTES gene are associated with several viral and non-viral diseases. Association studies have invariably indicated a lack of association between RANTES gene SNPs and HBV infection in ethnic populations, even though RANTES gene SNPs exhibit distinct ethnic distributions. Despite the high prevalence of HBV infections in Saudi Arabia, no studies have been made concerning a possible relationship between RANTES gene polymorphisms and susceptibility to and progression of HBV infection. We examined -403G>A and -28C>G RANTES gene variants in 473 healthy controls and 484 HBV patients in ethnic Saudi populations. Significant differences were found in the genotype and allele distributions of the SNPs between the controls and the HBV patients. Both SNPs were significantly linked to viral clearance in these subjects. Our data demonstrate for the first time in a Saudi population, a relationship between the RANTES gene polymorphisms and the clinical course of HBV infection and underscore the importance of evaluating the genetic background of the affected individual to determine how it may affect disease progression.

Activation of protein kinases by insulin and non-hydrolyzable GTP analogs in permeabilized 3T3-L1 adipocytes

The molecular events that lead from the interaction of insulin with its receptor to the activation of protein serine/threonine kinases are still unknown. In this study, we have examined the role of GTP-binding proteins in this signaling pathway using differentiated 3T3-L1 adipocytes permeabilized with alpha-toxin from Staphylococcus aureus. Addition of GTP gamma S (guanosine 5'-O-(3-thiotriphosphate)) or insulin to such permeabilized cells markedly increases protein kinase activities in cell lysates using the microtubule-associated protein-2 kinase substrate peptide KRELVE-PLTPSGEAPNQALLR, which contains the threonine 669 phosphorylation site on the epidermal growth factor receptor. Similar stimulations of protein kinase activity by these agents are observed using the peptide KRRRLASLAA, which is selectively phosphorylated by ribosomal protein S6 kinases. The effects of insulin and GTP gamma S are not additive. Importantly, the GTP-binding protein antagonist GDP beta S (guanosine 5'-O-(2-thiodiphosphate)) inhibits the activation of the protein kinase activities by insulin in permeabilized 3T3-L1 adipocytes. These data are consistent with the hypothesis that activation of Ras or other GTP-binding proteins is a key element of the signaling mechanism whereby insulin receptor tyrosine kinase activates the microtubule-associated protein-2 kinase cascade.

An insulin-stimulated kemptide kinase purified from rat liver is deactivated by phosphatase 2A

Insulin action leads to the rapid stimulation of a cytosolic Kemptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly) kinase (KIK) that has been recently purified to near homogeneity (Klarlund, J. K., Bradford, A. P., Milla, M. G., and Czech, M. P. (1990) J. Biol. Chem. 265, 227-234). To examine its activation mechanism, purified KIK was treated with purified protein phosphatases. The catalytic subunit of phosphatase 2A inhibited the activity of control KIK by about 50% and abolished the 5-fold elevation in KIK activity due to insulin action. The catalytic subunit of phosphatase 1 with equivalent activity based on dephosphorylation of 32P-labeled phosphorylase alpha had no effect on either control or insulin-stimulated KIK activity. The deactivation of insulin-stimulated KIK by phosphatase 2A was time- and concentration-dependent and was blocked by phosphatase inhibitors. The purified native complexes of phosphatase 2A, phosphatase 2A1, and phosphatase 2A2 similarly deactivated KIK. Analyis of control or insulin-stimulated KIK with two antiphosphotyrosine antibodies by immunoblotting and immunoprecipitation failed to detect the presence of phosphotyrosine in the kinase. These results indicate that KIK is activated by phosphorylation as part of a kinase cascade emanating from insulin receptor stimulation.

An insulin-sensitive cytosolic protein kinase accounts for the regulation of ATP citrate-lyase phosphorylation

Purified rat liver ATP citrate-lyase is phosphorylated on serine residues by an insulin-stimulated cytosolic kinase activity partially purified from rat adipocytes [Yu, Khalaf & Czech (1987) J. Biol. Chem. 262, 16677-16685]. The Km for lyase phosphorylation by this hormone-sensitive kinase activity is approx. 3 microM. Two-dimensional tryptic-peptide mapping of the 32P-labelled lyase reveals that the kinase-catalysed phosphorylation occurs primarily on a specific peptide. In intact 32P-labelled adipocytes, insulin enhances the serine phosphorylation of ATP citrate-lyase by 2-3-fold. Tryptic digestion of the 32P-labelled lyase immunopurified from insulin-treated adipocytes also yields one major phosphopeptide. 32P-labelled lyase tryptic peptides derived from labelling experiments in vitro and in vivo exhibit identical electrophoretic and chromatographic migration profiles. Furthermore, radio-sequencing of the phosphopeptide from lyase 32P-labelled in vitro indicates that serine-3 from the N-terminus is phosphorylated by the insulin-stimulated cytosolic kinase, in agreement with previous studies on the position of the phosphoserine residue in ATP citrate-lyase isolated from insulin-treated cells. Taken together, the similarity in site-specific phosphorylation of ATP citrate-lyase from insulin-treated adipocytes to that catalysed by the hormone-activated cytosolic kinase in vitro strongly suggests that this kinase mediates insulin action on lyase phosphorylation in intact cells.

[Glucose tolerance and electrolyte metabolism in nifedipine and nifedipine dihydroergotoxin treated healthy subjects]

The effects of three oral doses of nifedipine 20 mg or nifedipine 20 mg/dihydroergotoxin 2 mg (Pontuc, HN 85) during three subsequent days on an oral glucose load (100 g) were compared to placebo. Neither drug altered the glucose load or inhibited the secretion of insulin or C-peptide. The fall of serum potassium was also identical to controls. Basal plasma norepinephrine concentrations were lower following nifedipine/dihydroergotoxine than after nifedipine alone (2 p less than 0.05). A decrease of the serum sodium concentration by 2 mmol/l was observed with nifedipine but not with the combined drugs.

Insulin stimulates a novel Mn2+-dependent cytosolic serine kinase in rat adipocytes

The cytosolic fraction of insulin-treated adipocytes exhibits a 2-fold increase in protein kinase activity when Kemptide is used as a substrate. The detection of insulin-stimulated kinase activity is critically dependent on the presence of phosphatase inhibitors such as fluoride and vanadate in the cell homogenization buffer. The cytosolic protein kinase activity exhibits high sensitivity (ED50 = 2 X 10(-10) M) and a rapid response (maximal after 2 min) to insulin. Kinetic analyses of the cytosolic kinase indicate that insulin increases the Vmax of Kemptide phosphorylation and ATP utilization without affecting the affinities of this enzyme toward the substrate or nucleotide. Upon chromatography on anion-exchange and gel filtration columns, the insulin-stimulated cytosolic kinase activity is resolved from the cAMP-dependent protein kinase and migrates as a single peak with an apparent Mr = 50,000-60,000. The partially purified kinase preferentially utilizes histones, Kemptide, multifunctional calmodulin-dependent protein kinase substrate peptide, ATP citrate-lyase, and acetyl-coenzyme A carboxylase as substrates but does not catalyze phosphorylation of ribosomal protein S6, casein, phosvitin, phosphorylase b, glycogen synthase, inhibitor II, and substrate peptides for casein kinase II, protein kinase C, and cGMP-dependent protein kinase. Phosphoamino acid analyses of the 32P-labeled substrates reveal that the insulin-stimulated cytosolic kinase is primarily serine-specific. The insulin-activated cytosolic kinase prefers Mn2+ to Mg2+ and is independent of Ca2+. Unlike ribosomal protein S6 kinase and protease-activated kinase II, the insulin-sensitive cytosolic kinase is fluoride-insensitive. Taken together, these results indicate that a novel cytosolic protein kinase activity is activated by insulin.

Insulin stimulates the tyrosine phosphorylation of a Mr = 160,000 glycoprotein in rat adipocyte plasma membranes

The action of insulin on tyrosine phosphorylation of plasma membrane-associated proteins in rat adipocytes was investigated. Incubation of plasma membranes from insulin-treated adipocytes with [gamma-32P] ATP results in a marked increase in tyrosine phosphorylation of Mr = 160,000 (P160) and Mr = 92,000 proteins when compared to controls. Based on the immunoreactivities of these two proteins with anti-insulin receptor antibodies, the Mr = 92,000 species is identified as the insulin receptor beta subunit while P160 is unrelated to the receptor structure. P160 appears to be a glycoprotein as evidenced by its adsorption to wheat germ agglutinin-agarose. The tyrosine phosphorylation of P160 exhibits a rapid response to insulin (maximal within 2 min at 37 degrees C) and is readily reversed following removal of the free hormone by anti-insulin serum. The time courses of insulin-stimulated phosphorylation as well as the dephosphorylation of P160 coincide with those of the activation and deactivation of the insulin receptor kinase in the same plasma membrane preparation. Concanavalin A and hydrogen peroxide mimic insulin stimulation of the insulin receptor kinase and enhance the tyrosine phosphorylation of P160. Isoproterenol, epidermal growth factor, and phorbol diester are without effects. Analysis of the insulin dose-response relationship between P160 tyrosine phosphorylation and insulin receptor kinase activity reveals that maximal phosphorylation of P160 occurs when only a fraction (25%) of the receptor kinase is activated by the hormone. A similar relationship between these two parameters is observed for the insulinomimetic agent hydrogen peroxide. The close correlation between the level of P160 phosphorylation and insulin receptor kinase activity suggests that P160 may be tyrosine phosphorylated by the receptor kinase following receptor kinase activation by the hormone or insulin-like agents. This hypothesis is further supported by the finding that the insulin receptor kinase is the only insulin-sensitive tyrosine kinase detectable in adipocyte plasma membranes under the conditions of our experiments.

Insulin stimulates a membrane-bound serine kinase that may be phosphorylated on tyrosine

Triton X-100-solubilized high-density microsomes from insulin-treated rat adipocytes exhibit a marked increase in serine/threonine and tyrosine kinase activities toward exogenous histone when compared to controls. The insulin-dependent activation of microsomal histone kinase activities occurs within the physiological range of hormone concentrations (ED50 = 0.6 nM). The hormone-enhanced histone phosphorylation by the high-density microsomes appears to be catalyzed by two distinct kinases, based on their differential interaction with wheat germ agglutinin-agarose. The insulin-sensitive serine/threonine kinase is not retained by The insulin-sensitive serine/threonine kinase is not retained by the lectin column, whereas the tyrosine kinase appears to be a glycoprotein as evidenced by its adsorption to the immobilized lectin. The insulin-stimulated serine/threonine kinase exhibits preferential phosphorylation of histone and Kemptide (synthetic Leu-Arg-Arg-Ala-Ser-Leu-Gly) compared to a number of other peptide substrates. The substrate specificity of this serine/threonine kinase shows that it is distinct from the kinases that phosphorylate ribosomal protein S6, casein, phosvitin, ATP citrate lyase, and glycogen synthase and from multifunctional calmodulin-dependent, cAMP- and cGMP-dependent, and Ca2+/phospholipid-dependent protein kinases. Furthermore, 22% of the insulin-sensitive serine/threonine kinase activity can be adsorbed by monoclonal anti-phosphotyrosine antibodies immobilized on agarose. Its adsorption is specifically inhibited by excess free phosphotyrosine but not phosphoserine or phosphothreonine. The data suggest that this insulin-stimulated serine/threonine kinase in adipocyte high-density microsomes is tyrosine-phosphorylated, consistent with the hypothesis that the stimulatory action of insulin on this kinase may be mediated by tyrosine phosphorylation.

Efficiency of growth in mice with a major gene for rapid postweaning gain

Previous research in this laboratory demonstrated the existence of a major gene (hg), inherited as a homozygous recessive, which increases postweaning growth by 40 to 50% in C57Bl/6 mice (Ch) compared to the same genetic stock without the major gene (CH). Although its effect has not been previously evaluated, this single recessive allele is also in a line of mice selected for rapid postweaning gain for over 70 generations. Gh represents that line of mice with the major gene for growth (hg) in the growth-selected background and GH the growth-selected background without the major gene. Total body weight, daily weight gain, feed consumption and gain/feed, measured daily from 21 to 42 d of age, were all significantly greater (p less than .01) in the two lines with the hg/hg genotype (Ch and Gh) compared with their respective control lines (CH and GH). Differences in body composition at 42 d of age between CH compared with Ch and GH compared with Gh were accounted for by difference in body weight. Gross and net energetic efficiency, calculated assuming a similar maintenance energy requirement, were improved (P less than .01) in Ch and Gh compared to CH and GH, respectively. The results demonstrated that hg influences growth in growth-neutral and growth-selected backgrounds. The gene also alters energy metabolism by increasing energetic efficiency of growth and(or) decreasing maintenance energy requirement.