'Halomonas saudii' sp. nov., a new bacterial species isolated from marine plant Halocnemum strobilaceum.

We report here the main characteristics of 'Halomonas saudii' strain Saudii DR2 (CSUR P2512), a new species of the Halomonas genus that was isolated from a rhizosphere of Halocnemum strobilaceum in April 2015.

New Delhi metallo-ß-lactamase (NDM-1): an update.

New Delhi metallo-ß-lactamase (NDM-1) is a novel broad spectrum carbapenemase with ability to inactivate all ß-lactams except aztreonam. However, most of the NDM-1-producers also produce aztreonam hydrolysing-ß-lactamases thereby making these pathogens absolutely resistant to all ß-lactams. The bla(NDM-1) gene encodes a 27.5 kDa protein of 269 amino acids. It shares very little identity with other metallo-ß-lactamases. Maximum identity has been observed to VIM-1/VIM-2 (32.4%). This mini-review is an update of the scientific literature for the said enzyme. Following the recommendation of David livermore, we further propose to combine "aztreonam" and "inhibitor of the most frequently encountered aztreonam hydrolysing-ß-lactamases in a given setting" as a possible strategy against NDM-1-producers. The inhibitor should be 'versatile' as well, i.e. it should have the ability to inhibit most of the variants of aztreonam hydrolysing-ß-lactamases prevalent in the concerned setting. We strongly recommend surveillance studies using aztreonam/NXL-104-combination against NDM-1-producing pathogens in different geographical regions across the globe.

Frequency of Mediterranean mutation among a group of Saudi G6PD patients in Western region-Jeddah.

Glucose-6-phosphate dehydrogenase deficiency (G6PD), a common human enzymatic defects characterized by extreme molecular and biochemical heterogeneity is found to have a variable frequency in different regions. The molecular basis of polymorphic variants in Saudi Arabia have yet to be fully addressed to. Accordingly, a study was designed to determine the frequency of G6PD gene mutations in G6PD deficient cases. From forty-seven unrelated G6PD-deficient subjects, DNA was extracted individually from peripheral blood samples and exons 6 and 7 of the G6PD gene were amplified by PCR. Mutation analysis was carried out by using conformation sensitive gel electrophoresis (CSGE), followed by direct DNA sequencing. The results showed definite altered CSGE patterns. Two mutations were resolved in exon 6 of G6PD gene; Mediterranean mutation and Sibari mutation, not previously reported so far; while no mutation was detected in exon 7. The frequency of exons 6 mutations responsible for G6PD deficiency (Mediterranean type) is reported for the first time from this region, with a figure of 50.1%. The absence of other mutations in exon 7 causing G6PD deficiency points to the low genetic diversity in the studied population.

The effect of cigarette or sheesha smoking on first-trimester markers of Down syndrome.

OBJECTIVE: To investigate the influence of cigarette or sheesha smoking on first-trimester markers of Down syndrome. DESIGN: A prospective observational study. SETTING: Primary care centres and antenatal clinics of Maternity and Children Hospital, King Abdulaziz University Hospital and New Jeddah Clinic Hospital, Jeddah, Saudi Arabia. POPULATION: Women with a singleton pregnancy who were either nonsmokers (n = 1736) or cigarette smokers (n = 420) or sheesha smokers (n = 181). METHODS: Fetal nuchal translucency thickness (fetal NT), maternal serum free beta-human chorionic gonadotrophin (free beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) were measured at 11 weeks 0 days to 13 weeks 6 days of gestation in all women. Women were grouped according to smoking status, confirmed by maternal serum cotinine measurements, and analyte levels between groups were compared. MAIN OUTCOME MEASURES: Fetal NT, maternal serum free beta-hCG, PAPP-A and cotinine measurements. RESULTS: Compared with nonsmoking women, fetal NT was significantly increased and free beta-hCG and PAPP-A levels were significantly decreased in both cigarette and sheesha smokers. There were significant relationships between all three markers and the number of sheeshas consumed per day. CONCLUSIONS: Cigarette and sheesha smoking significantly affect first-trimester markers of Down syndrome (fetal NT, free beta-hCG and PAPP-A). Correction for this effect in women who smoke might improve the effectiveness of first-trimester screening for Down syndrome in these women. The underlying mechanism(s) relating smoking to the changes in first-trimester markers require further studies.

A novel von Willebrand disease-causing mutation (Arg273Trp) in the von Willebrand factor propeptide that results in defective multimerization and secretion.

In this report we describe the molecular defect underlying partial and severe quantitative von Willebrand factor (VWF) deficiencies in 3 families previously diagnosed with types 1 and 3 Von Willebrand-disease. Analysis of the VWF gene in affected family members revealed a novel C to T transition at nucleotide 1067 of the VWF complemetary DNA (cDNA), predicting substitution of arginine by tryptophan at amino acid position 273 (R273W) of pre-pro-VWF. Two patients, homozygous for the R273W mutation, had a partial VWF deficiency (VWF:Ag levels of 0.06 IU/mL and 0.09 IU/mL) and lacked high-molecular weight VWF multimers in plasma. A third patient, also homozygous for the R273W mutation, had a severe VWF deficiency (VWF:Ag level of less than 0.01 IU/mL) and undetectable VWF multimers in plasma. Recombinant VWF having the R273W mutation was expressed in COS-7 cells. Pulse-chase experiments showed that secretion of rVWFR273W was severely impaired compared with wild-type rVWF. However, the mutation did not affect the ability of VWF to form dimers in the endoplasmic reticulum (ER). Multimer analysis showed that rVWFR273W failed to form high-molecular-weight multimers present in wild-type rVWF. We concluded that the R273W mutation is responsible for the quantitative VWF deficiencies and aberrant multimer patterns observed in the affected family members. To identify factors that may function in the intracellular retention of rVWFR273W, we investigated the interactions of VWF expressed in COS-7 cells with molecular chaperones of the ER. The R273W mutation did not affect the ability of VWF to bind to BiP, Grp94, ERp72, calnexin, and calreticulin in COS-7 cells. (Blood. 2000;96:560-568)

Two novel type 2N von Willebrand disease-causing mutations that result in defective factor VIII binding, multimerization, and secretion of von Willebrand factor.

Two novel mutations, a T-to-C transition at nucleotide 2612 and a T-to-G transversion at nucleotide 3923 of the von Willebrand factor (vWF) complementary DNA, were detected by analysis of the vWF gene in DNA from members of 2 families with atypical von Willebrand disease. The T2612C transition predicts substitution of cysteine by arginine at amino acid position 788 (C788R), and the T3923G transversion predicts substitution of cysteine by glycine at position 1225 (C1225G) of pre-pro-vWF. The patients homozygous for the C788R and C1225G mutations both had a partial vWF deficiency (0. 18 IU/mL and 0.07 IU/mL vWF antigen, respectively); vWF in plasma from patients homozygous for either the C788R or the C1225G mutation failed to bind factor VIII and lacked high molecular weight multimers. Recombinant (r) vWF molecules having the C788R or C1225G mutation were expressed in COS-7 cells. Both rvWF C788R and rvWF C1225G exhibited significantly impaired secretion and failed to bind factor VIII. Recombinant vWF C788R in COS-7 culture medium showed a severe reduction in high molecular weight multimers, whereas rvWF C1225G showed a very mild reduction in high molecular weight multimers when compared with wild-type rvWF. (Blood. 2000;95:2000-2007)