Transformation in Aspergillus ochraceus

Mutants (lysine requiring) of Aspergillus ochraceus were kept under starvation conditions for 15 days and finally were treated with DNA of a 40-h-old culture of the wild strain. The donor DNA-treated mutant conidia were then grown on plates containing minimal medium at 28 degrees C for 4 days. The number of transformed cells was estimated by colony counting and hence percentage transformants. The transforming activity of the donor DNA was found to be inhibited by the action of heat and variation of pH, and also varied with the period of starvation and with the concentration of donor DNA.

Comparative efficacy of furazolidone and nalidixic acid in the empirical treatment of acute invasive diarrhea: randomized clinical trial

Efficacy of furazolidone and nalidixic acid was compared in a randomized trial involving 72 children with acute invasive diarrhea. Thirty six children received furazolidone (7.5 mg/kg/day) and 36 children received nalidixic acid (55 mg/kg/day). Clinical characteristics of the two treatment groups were comparable on admission. Of these, 34 children in furazolidone treated group and 29 children in nalidixic acid treated group completed the full course of treatment and were analyzed finally for clinical efficacy. Clinical cure was observed in 29(85.3%) children treated with furazolidone and 29(100.0%) children treated with nalidixic acid. Nalidixic acid treated group had statistically significantly higher cure rate (p = 0.039) as compared to furazolidone treated group. However, 85% cure rate in furazolidone treated group may be potentially useful for the treatment of acute invasive diarrhea because of decreasing efficacy of nalidixic acid against shigellosis in many countries.

Thermodynamic characterization of the cooperativity of 40S complex formation during the initiation of eukaryotic protein synthesis

The first step in mammalian protein synthesis is the formation of the 40S initiation complex, composed of the 40S ribosomal subunit (R), mRNA (M, here, a 10-mer oligoribonucleotide analogue containing the initiation codon), and the quaternary complex (Q, composed of eIF-2, GTP, Met-tRNA(fMet), and the ancillary protein factor Co-eIF-2C). The interdependence of the binding of R, M, and Q in forming the 40S complex is currently unclear. We have determined the thermodynamic parameters that characterize these interactions. The binary constants for R+M and Q+M were determined spectroscopically, measuring changes in the anisotropy of the fluorescence emission of 3'-fluorescein labeled M. The other binary constant, for Q+R, and the ternary constant were determined from Millipore filtration assays using radiolabeled Met-tRNA(fMet). The association constants for the binary reactions were as follows: Ka(Q,M) < or = 0.14 x 10(6) M-1, Ka(R,M) = 1.78 x 10(6) M-1, and Ka(Q,R) = 0.94 x 10(6) M-1. The binding of Q to R.M was markedly greater than that of Q to R [Ka(Q,R.M)/Ka(Q,R) > 62]. High cooperativity for this interaction occurs in either a single-site model or in lattice models for the binding of M to R. Data obtained using five other RNA 10-mers, each with the sequence altered at the AUG codon, suggest that this cooperativity is AUG dependent. The data are consistent with a scheme in which mRNA and Q bind independently to the 40S ribosome, but when the AUG codon is properly aligned with Q, a conformational change results in a 2.4 kcal/mol stabilization of the complex.

Mechanism of action of an eukaryotic initiation factor-2 (eIF-2) associated 67 kDa glycoprotein (p67) and an eIF-2 kinase (dsI)

Mechanism of regulation of eIF-2 alpha-subunit phosphorylation by dsI and p67 was studied. The results are as follows: (1) At low dsI concentration, p67 protected equimolar concentration of eIF-2. (2) At high dsI concentration, dsI efficiently phosphorylated eIF-2 alpha-subunit even when equimolar concentrations of both p67 and eIF-2 were present. Significantly increased p67 concentration was necessary to protect eIF-2 alpha-subunit at high dsI concentration. (3) dsI was also phosphorylated as it phosphorylated eIF-2 alpha-subunit. p67 inhibited both eIF-2 alpha-subunit and dsI phosphorylation similarly. (4) Although the [32P]-labelled dsI formed during the reaction could be effectively chased upon subsequent addition of excess unlabelled eIF-2 and ATP, the [32P] labelled eIF-2 formed under identical conditions, retained most of the radioactivity. (5) dsI coimmunoprecipitated with three subunit eIF-2 and p67 inhibited this coimmunoprecipitation reaction. It has been proposed: Three subunit eIF-2 and free p67 are in equilibrium with eIF-2 bound to p67 and, eIF-2.p67 complex is resistant to dsI phosphorylation. Activated dsI is already phosphorylated. At high concentration, dsI(P) can bind to free three subunit eIF-2 and form eIF-2.dsI(P) complex. dsI(P) in this complex then transfers its phosphoryl residue to eIF-2 and forms eIF-2 alpha(P) in an irreversible reaction. In a subsequent reaction, unphosphorylated dsI is autophosphorylated using [gamma 32P]-ATP and the cycle continues. Inhibition of eIF-2 alpha-subunit phosphorylation by p67 blocks this phosphorylation cycle and consequent dsI phosphorylation.

Regulation of eIF-2 alpha-subunit phosphorylation in reticulocyte lysate

An eIF-2 associated 67-kDa protein (p67) protects eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation and promotes protein synthesis in the presence of active eIF-2 kinase(s). p67 is a glycoprotein and contains multiple O-linked GlcNAc moieties. We have now studied the roles of hemin, p67, and the glycosyl residues on p67 in the regulation of eIF-2 alpha-subunit phosphorylation in reticulocyte lysates. The results are as follows: (i) Both hemin and p67 inhibited HRI (heme-regulated protein synthesis inhibitor) and dsI (double-stranded RNA activated protein synthesis inhibitor) catalyzed phosphorylation of eIF-2 alpha-subunit in vitro. However, only hemin, and not p67, inhibited casein kinase catalyzed phosphorylation of eIF-2 beta-subunit. (ii) Only p67, and not hemin, inhibited eIF-2 alpha-subunit phosphorylation by eIF-2 kinase(s) in reticulocyte lysate. Significant eIF-2 alpha-subunit phosphorylation was observed even in the presence of hemin when p67 in the reticulocyte lysate was removed by treatment with p67 antibodies. (iii) Reticulocyte lysate contains a p67-deglycosylase in latent form, and hemin prevents activation of this deglycosylase. In the absence of hemin, this p67-deglycosylase is activated. Once activated in the absence of hemin, the activated deglycosylase deglycosylates p67, even in the presence of hemin. This inactivates p67 and allows eIF-2 kinase to phosphorylate eIF-2 alpha-subunit and inhibit protein synthesis. Protein synthesis in reticulocyte lysate is thus regulated by two novel cascades of covalent modifications: protein deglycosylation leading to protein phosphorylation.

Characteristics of the eukaryotic initiation factor 2 associated 67-kDa polypeptide

A eukaryotic initiation factor 2 (eIF-2) associated 67-kDa polypeptide (p67) protects the eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation, and this promotes protein synthesis in the presence of active eIF-2 kinase(s), [Datta, B., et al. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3324-3328]. This report presents the results of studies related to characteristics of p67 action and the mechanism of p67:eIF-2 interaction: (1) p67 antibodies inhibited protein synthesis in hemin-supplemented rabbit reticulocyte lysates, and such inhibition was reversed by preincubation of the antibodies, specifically with p67. (2) p67 inhibited HRI- and dsI-catalyzed phosphorylations of the eIF-2 alpha-subunit and histones, but it did not inhibit casein kinase catalyzed phosphorylation of the eIF-2 beta-subunit. (3) p67 bound specifically to the eIF-2 gamma-subunit. p67 co-immunoprecipitated with the eIF-2 subunits when a p67/eIF-2 mixture was treated with p67 or eIF-2 subunit antibodies and protein A agarose. However, when eIF-2 was preincubated specifically with the eIF-2 gamma-subunit antibodies, subsequent co-immunoprecipitation of p67 with the eIF-2 subunits was completely inhibited. Similarly, preincubation of p67 and p67 antibodies prevented subsequent p67 binding to eIF-2. Preincubation of eIF-2, with either eIF-2 alpha- or beta-subunit antibodies, had no effect on p67 co-immunoprecipitation with the eIF-2 subunits. (4) p67:eIF-2 interaction is necessary for p67 activity to protect the eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Transformation and expression of a staphylococcal plasmid in Escherichia coli

A multiple antibiotic-resistant Staphylococcus aureus, was found to possess three plasmid bands in agarose gel electrophoresis. A plasmid of approximately 4.3 kb (pMC790/2) was found to code for ampicillin and tetracycline resistance and to have one EcoRI site when transformed into S. aureus RN 4220. pMC790/2 in unmodified form was transformed into a recA- E. coli at a frequency of 1.2 x 10(4) transformants/micrograms of plasmid DNA. Plasmid (pMC790/2) replicated, maintained itself stably and expressed far better in the E. coli host than in S. aureus.

Pulmonary function studies in healthy non-smoking women of Calcutta

Pulmonary function measurements were made in 230 healthy non-smoking women from Calcutta with an age range of 20-59 years. The tests consisted of vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory volume in one second as a percentage of forced vital capacity (FEV1%), forced expiratory time (FET), maximum voluntary ventilation, uncontrolled frequency (MVVF), forced expiratory flow (FEF200-1200ml), forced mid-expiratory flow (FEF25-75%), forced end-expiratory flow (FEF75-80%) and peak expiratory flow rate (PEFR). Except for PEFR, all the measurements were made with the help of two 9-litre closed-circuit-type expirographs using standard spirometric techniques. PEFR was recorded with the help of two Wright peak flow meters. Prediction formulae were derived on the basis of physical characteristics. Age and height were found to be the significant predictor variables for VC, FVC and FEV1, while only age was significant for FEV1%. The FVC and FEV1 values of the subjects, standardized for age and height, are much lower than those of Americans, Europeans and Jordanians. On comparison with data reported from other parts of India, it was revealed that the VC and FEV1 values of the current study, after adjustment for age and height, were much higher than those of Southern Indians but comparable with those of North-Western Indians.

Comparative study of the properties of plasmid mediated staphylococcal beta-lactamase as expressed in Escherichia coli

An unmodified natural plasmid of Staphylococcal origin having beta-lactamase determinant was introduced by transformation into Gram-negative Escherichia coli HB101 recA-SmR (plasmidless). Beta-lactamase of Staphylococcus aureus is extracellular. In recipient transformed E. coli HB101, the enzyme shows periplasmic location. The enzyme is expressed well in E. coli, and the basal level of enzyme production in E. coli, is approximately 3-4 fold higher than that of S. aureus. Beta-lactamase is inducible both in S. aureus and E. coli. Enzymatic properties as indicated by substrate profile and Km values are found to be similar.

Maximal aerobic capacity of Bengali girl athletes of different sports activities

The maximal aerobic capacity (VO2max) and related cardiorespiratory parameters were determined on 67 Bengalee (Indian) girl athletes having nine different sports activities. VO2max was determined with a bicycle ergometer. The highest value for VO2maxl.min-1 was obtained by javelin throwers (1.95), being followed by pentathletes (1.92) and long-distance runners (1.90), whereas the lowest value was achieved by handballers (1.45). When VO2max was expressed in ml.kg-1.min-1, the long-distance runners registered the highest mean value (43.0), which was significantly higher than that of basketballers (34.9), handball players (36.2), badminton players (34.4), and swimmers (36.0). For this measurement, the sprinters (40.0), pentathletes (40.3), javelin throwers (40.0), and jumpers (39.4) did not differ significantly with each other, but each of the groups was significantly superior to basketballers, handballers, badminton players, and swimmers. No significant difference was also found amongst the latter groups. VO2maxl.min-1 was found to be significantly correlated with all the physical characteristics. It was predicted on the basis of age, height, weight, and body surface area using stepwise regression method.

A new method of plasmid DNA preparation by sucrose-mediated detergent lysis from Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive)

A simple and cheap method of plasmid DNA preparation from both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) organism is presented here. In this method, in place of the high-priced chemicals lysostaphin and lysozyme which are commonly used for removal of cell-wall during plasmid DNA preparation from gram-positive and gram-negative bacteria, respectively, only sucrose has been used. Firstly, bacteria is treated with Trizma (pH 8.0) containing 100% sucrose (hypertonic solution). Due to this osmotic shock, protoplasm covered by the plasma membrane of bacteria possibly shrinks and becomes detached from the cell-wall. Osmotically sensitive cells thus formed, from gram-positive (S. aureus) and gram-negative (E. coli) bacteria, are finally lysed by the lysis mixture, containing brij 58 and sodium deoxycholate. The lysate is centrifuged at 15,000 rpm for 30 min to pellet the cell debris. The supernatant containing plasmid DNA is treated with either polyethylene glycol or isopropanol. The precipitate which contains plasmid DNA is dissolved in a buffer containing Tris, EDTA, NaCl, and sodium dodecyl sulfate (pH 8.0); thus protein is denatured and removed. Finally, RNA is removed by RNase treatment. The average yield of staphylococcal plasmid DNA as well as plasmid pBR322 from E. coli HB101 in 100% sucrose-treated preparations is greater than that of lysostaphin- and lysozyme-treated preparations. This method is applicable for both large-scale and small-scale preparations. The substrate activity for restriction enzyme, cloning, transforming ability, and electron microscopic profile of the plasmid DNA prepared by this method remains unaltered.

A newly discovered habitat of Anopheles stephensi in present-day Calcutta with evidence of natural malarial infection

In Calcutta adult Anopheles stephensi mosquitoes were captured in significantly greater numbers from temporary human shelters than from their conventional resting places, such as brick built indoor rooms and cattlesheds, pointing out a change of behaviour in seeking their resting places which may have occurred due to excitorepelletory action of insecticides used indoors in bygone days.

Pulmonary function studies in healthy non-smoking men of Calcutta

Pulmonary function measurements were made in 104 healthy non-smoking men from Calcutta with an age range of 20-59 years. Except for peak expiratory flow rate (PEFR), all the measurements were made with the help of two 9L closed-circuit type expirographs using standard spirometric techniques. PEFR was recorded by two Wright peak flow meters. Prediction formulae were derived on the basis of age and height for all the ventilatory tests except for FEV1%, FET and PEFR. These were predicted from age only. The prediction equation for VC, FVC, FEV1, FEV1%, MVVF and PEFR were reliable, but those for forced expitatory flows and time were not. The FVC and FEV1 values of the present subjects, standardized for age and height, were much lower than those of Americans, Caucasians, Europeans and Canadians but similar to those of Pakistani healthy adults. On comparison with the data reported from other parts of our country, it was revealed that the VC and FEV1 values of the current study, after adjustment of age and height, were much higher than those of southern Indians but comparable with those of north-western Indians.

Critical laboratory values - an experience in Apollo Hospitals Dhaka

Reporting of laboratory critical values has become important for patient safety as described by recent guidelines in National Patient Safety Goals of the Joint Commission on Accreditation of Healthcare Organizations (JCAHO). The use of critical values reporting was adopted as a requirement in the Clinical Laboratory Improvement Amendments (CLIA'88). Herein, we reported the results of an analysis of 4260 consecutive laboratory critical values from July 2007 to June 2008 at our institution, a large tertiary medical center. We evaluated critical value reporting by parameters, laboratory speciality (Clinical Chemistry & Hematology), clinical care area (IPD, OPD, Emergency), and Turn around time. Factors leading to delays in critical value reporting are identified, and we describe approaches to improving this important operational and patient safety.DOI: 10.3329/pulse.v3i1.6544Pulse Vol.3(1) July 2009 p7-11