Biomass and lipids from lactose or whey by Trichosporon beigelii

The yeast Trichosporon beigelii produced the highest amount of biomass when grown in chemical-defined medium with a ratio of carbon source to nitrogen source of 30:1. On the other hand, carbon-limited medium (C-N ratio 2:1) enhanced unsaturated fatty acids synthesis. The yeast efficiently converted unsalted whey lactose to biomass, while sodium chloride in whey raised lactose assimilation to single-cell oil (SCO).     

Identification of subsidiary catalytic groups at the active site of beta-ketoacyl-CoA thiolase by covalent modification of the protein

beta-Ketoacyl-CoA thiolase (acyl-CoA:acetyl-CoA C-acyltransferase, EC 2.3.1.16) is known to possess sulfhydryl groups of cysteines at the active site that are essential for its catalytic activity. Other groups at the active site that participate in the catalytic process were identified by using anhydride reagents which covalently modify the protein by specifically reacting with any amino groups potentially present at the active site. Since these reagents may also react with thiol groups, the enzyme's amino groups were modified after masking the cysteine thiols present by an alkylalkane thiosulfonate-type reagent, methyl methanethiol-sulfonate (MMTS), that selectively formed a disulfide bridge, thus generating an inactive thiolmethylated enzyme. When this procedure was followed, the enzyme could be undoubtedly modified at its amino by the anhydride reagent, leading to a doubly modified protein. The thiomethyl group could then be removed by reduction with dithiothreitol, yielding an enzyme modified solely on the amino residues. The amino group could be unblocked in turn by exposure to acidic pH. The different anhydrides inactivated thiolase, but only acetoacetyl coenzyme A (AcAcCoA) provided any protection against inactivation. When thiolmethylcitraconyl thiolase was reduced with dithiothreitol the enzyme remained inactive, but when the doubly modified enzyme was exposed to pH 5 then the reduction led to formation of an active enzyme. These results are interpreted as demonstrating a role for an amino group at the enzyme active site. A catalytic mechanism is proposed for the enzyme which involves the amino group.     

Benzoylarginine peptidase and iminopeptidase profiles ofTreponema denticola strains isolated from the human periodontal pocket

Seven clinical isolates and the ATCC strain 35405 ofTreponema denticola, obtained from human periodontal pockets, were studied for peptidase activity with several chromogenic compounds as substrates. The cell sonicates of all strains hydrolyzed phenylazobenzyloxycarbonyl-l-prolyl-l-leucyl-glycyl-l-prolyl-d-arginine (a collagenase substrate), azocasein, and the 2-naphthylamines ofl-proline,l-hydroxyproline,l-pyrrolidine, and benzoyl-l-arginine, but the rates of hydrolysis varied considerably from strain to strain. Fast protein liquid chromatography on gel and anion exchange columns revealed further biochemical differences between the strains. The ATCC strain consistently produced several proline iminopeptidases, whereas four of the clinical isolates yielded high and three yielded low iminopeptidase activity. The ATCC strain and six clinical isolates displayed high benzoylarginine peptidase activity. The use ofN-l-prolyl-2-naphthylamine as substrate revealed more differences between the strains than other substrates. The substrate specificity of the enzymes discovered suggests that they may be important for the nutrition of the organism or in the protection of the organism against chemical defense factors present in the gingival pocket.     

Interaction of influenza virus proteins with planar lipid bilayers: A model for virion assembly

Changes in conductance of oxidized cholesterol planar lipid bilayers were measured following the incorporation of isolated surface glycoproteins; hemagglutinin and neuraminidase (HA+NA) or matrix protein (M-protein) of influenza virus. The conductance dependence of the lipid bilayers on the HA+NA or M-protein concentrations indicates different mechanisms of interaction of these viral proteins with the lipid bilayer. Adsorption of M-protein molecules on one side of the lipid bilayer affects the character of the HA+NA interaction with the opposite side. Planar lipid bilayers can be a useful model for investigation of the assembly of influenza virions and other enveloped viruses.     

Efficiency of Various Growth Media in Recovering Oral Bacterial Flora from Human Dental Plaque

MM10 sucrose blood agar (MM10 SB agar), N(2)C agar, Schaedler agar (SH agar), and mitis salivarius agar (MS agar) were tested for their ability to recover human dental plaque flora by a continuous anaerobic procedure and by a conventional anaerobic method. MM10 SB agar yielded higher recovery of bacteria from plaque samples as determined by the enumeration of colony-forming units (CFU). The CFU on N(2)C agar, SH agar, and MS agar were lower than MM10 SB agar when the continuous anaerobic procedure was used. The superior performance of MM10 SB agar was much more apparent when used for the cultivation of dental plaque by the conventional anaerobic method. Under these conditions the counts were consistently higher on MM10 SB agar as compared to the other media tested. However, the differential counts of Streptococcus sanguis and S. mutans from carious plaque samples were in general comparable on all culture media. Deletion of blood from MM10 SB agar did not lower counts. The elimination of dithiothreitol from this medium resulted in a significantly lower recovery of bacteria from the plaque samples when cultured by the conventional anaerobic method. The storage of MM10 SB agar for varying periods of time aerobic conditions did not seem to affect its performance. These findings suggest that MM10 SB agar is an ideal culture medium for the isolation, nonselective enumeration, and differential counts of bacteria present in normal and disease-associated plaques.     

Familial Leydig cell hypoplasia as a cause of male pseudohermaphroditism

A case of familial Leydig cell hypoplasia as a cause of male pseudohermaphroditism is described in two 46,XY female sibs. Biochemical and histologic evidence for such diagnosis is presented.     

Pollution characteristics and health risk assessment of potentially toxic elements in school playground soils: A case study of Lagos,Nigeria

Abstract

Soil samples were collected in February 2014 from 25 school playgrounds in Lagos, Nigeria to assess the potential adverse effects of the exposure of children to potentially toxic element (PTE). In each of the playgrounds, about 500?g of bulked soil samples were collected, dried, sieved, acid digested, and analyzed by inductively coupled plasma mass spectrometry (ICP‐MS). Results showed that soils studied were characteristically unpolluted as the average PTE concentration at each site did not exceed the soil guideline values. Considering the pollution assessment tools employed, some soil samples showed some form of anthropogenic input from PTE. Health risk assessment was employed to assess PTE exposure from ingestion, inhalation, and dermal contact. Result indicated that the highest risk is associated with ingestion followed by dermal contact and inhalation. For non‐carcinogenic effects, exposure to school playground soils poses no threat to children as the overall value of hazard index is less than the safe level of 1. For carcinogenic effects, only Cr and Ni were considered and were below the threshold of 1?×?10^–6. This study has demonstrated that minimal risk arises from the investigated playgrounds and that regular monitoring is required to keep the PTE contents low in soils to avoid risk to human health.

Abbreviations: SH, school playground; PTE, potentially toxic elements     

Modulation of gastric acid secretion by cannabinoids in rats

The current study aimed to evaluate the role of cannabinoid receptors in the regulation of gastric acid secretion and oxidative stress in gastric mucosa. To fulfill this aim, gastric acid secretion stimulated with histamine (5 mg/kg, subcutaneous [SC]), 2‐deoxy‐ d ‐glucose (D‐G) (200 mg/kg, intravenous) or ‐carbachol (4 μg/kg, SC) in the 4‐hour pylorus‐ligated rats. The CB1R agonist ( N‐arachidonoyl dopamine, 1 mg/kg, SC) inhibited gastric acid secretion stimulated by D‐G and carbachol but not in histamine, reduced pepsin content, and increased mucin secretion. Furthermore, it decreased malondialdehyde (MDA) and nitric oxide (NO) contents with an increase in glutathione (GSH) and paraoxonase 1 (PON‐1). Meanwhile, CB2R antagonist (AM630, 1 mg/kg, SC) inhibited gastric acid secretion stimulated by D‐G and reduced MDA and NO contents with an increase in GSH and PON‐1. Meanwhile, CB1R antagonist rimonabant or CB2R agonist GW 405833 had no effect on stimulated gastric acid secretion. Therefore, both CB1R agonist and CB2R antagonist may exert antisecretory and antioxidant potential in the stomach.     

Aberrant promoter methylation and reduced expression of p16 gene in esophageal squamous cell carcinoma from Kashmir valley: a high-risk area

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent cancer in Jammu and Kashmir region of India and has multi-factorial etiology involving dietary habits, genetic factors, and gene environmental interactions. Inactivation of the p16 gene expression by aberrant promoter methylation plays an important role in the progression of esophageal carcinoma. In the present investigation, we have studied the role of p16 promoter methylation in 69 histopathologically confirmed ESCC tissues and compared it with corresponding normal adjacent tissues for DNA methylation in the CpG island in the p16 promoter region by methylation-specific polymerase chain reaction (MSP) and p16 protein expression by immunoblotting. The results showed loss of p16 expression in 67% (46/69) of tumor tissues compared to only 3% in control tissues (2/69). Promoter methylation was observed in 52% (36/69) of tumor tissues and it gradually increased with the increasing severity of histological grades of the cancer (P = 0.0001). Loss of p16 expression with promoter methylation was observed in 26 of 36 cases (72%). Analysis of patients dietary habits revealed a strong association between promoter methylation and high consumption of hot salted tea (P < 0.05) which is a most favourite drink commonly consumed by Kashmiri people.