Role of iron ions in the production of hemolysin by toxigenic and nontoxigenic Vibrio cholerae of different serogroups

The hemolytic activity of ctx- and ctx+ V. cholerae, serogroups eltor and O39, in a medium free of FeCl3 was studied. During the cultivation in this medium, the strains of both V. cholerae serogroups proved to be capable of lysing sheep red blood cells in the Graig test, irrespective of the presence of ctx genes. The cultivation of V. cholerae ctx+ strains of both serogroups under such conditions facilitated the production of hemolysin with the same spectrum of lytic activity as hemolysin produced by ctx- strains.     

Hemolytic activity of Vibrio cholerae eltor and V. cholerae O139 toxigenic and nontoxigenic strains

A total of 20 ctx- and 16 ctx+ V. cholerae eltor strains, 20 ctx- and 22 ctx+ V. cholerae O139 strains were under study. Hemolytic activity was tested in modified Greig test with sheep, guinea pig and rabbit red blood cells. The comparative study of the hemolytic properties of V. cholerae O1 and O139 under different conditions of cultivation demonstrated their capacity of lysing sheep red blood cells (SRBC) irrespective of the presence of toxigenic properties. A wider spectrum of lytic activity of ctx- strains in Greig test with respect to red blood cells of different animals and the capacity of lysing SRBC, most resistant to the action of toxin, may be due to a considerably greater content of Hly+ clones in their population.     

Flora Europaea Notulae Systematicae ad Floram Europaeam spectantes No. 20 Corrigenda et Addenda

Following the publication of the last of the series of Flora Europaea Notulae, No. 20 in the Botanical Journal of the Linnean Society , 76: 297–384 (1978), a number of additions or alterations have been drawn to our attention. These are published in continuation.     

Highly sensitive electroimmunodiffusion method of detecting antigens on cellulose acetate film]

A highly sensitive electro-immunodiffusion test suggested by the authors for antigen detection on cellulose-acetate films consists of three stages: antigen concentration in a discontinuous buffer system on cellulose-acetate films; antigen detection on the same films by immunodiffusion using standard test system; to detect the precipitation bands the washed films are stained with protein dyes in case the reaction takes place in the zone of vision, or subject to further treatment by means of "plating" the precipitates with antiglobulin antibody or by radioautography. The method permits one to reveal the nanogram levels of alfa-fetoprotein and it may be applied for detection of antigens with different molecular weights and electrophoretic mobility.     

Gene clpP2Encoding Peptidase in the Synechocystissp. PCC 6803 Cyanobacterium Controls Cell Sensitivity to Photoinhibition

A homozygous insertion mutant with the inactivated clpP2gene, which encodes the proteolytic subunit of ATP-dependent peptidase, was obtained in the unicellular cyanobacterium Synechocystissp. PCC 6803. The mutant cannot grow under photoautotrophic conditions, but cells grown under heterotrophic conditions in a glucose-containing medium have active photosystems Iand II(PS Iand PS II). The loss of capacity for photoautotrophic growth is determined by a high sensitivity of mutant cells to the inactivating effect of light. Their incubation under light with an intensity above 10 E m^–2s^–1inhibits cell growth in culture and causes degradation of photosynthetic pigments. It is proposed that the ClpP2 peptidase is involved in the protection of Synechocystis6803 cells from photoinhibition.     

Inactivation of sll0136 gene in Synechocystis sp. PCC 6803 results in the disturbance in protein biogenesis of photosynthetic complexes

The genome of cyanobacterium Synechocystis sp. PCC 6803 contains the sll0136 (pepP) gene encoding the putative homolog of proline aminopeptidase PII (AMPPII) of the heterotrophic bacterium Escherichia coli. AMPPII is known to cleave the N-terminal amino acid residue of peptides and proteins only in the case of a penultimate proline position. The Synechocystis sp. PCC 6803 insertion mutant with inactivated pepP gene is characterized by the reduced content of phycobiliproteins and also proteins of photosystem II, which may be related to the reduced synthesis or stability of corresponding proteins. A possible involvement of PepP in biogenesis of proteins of the photosynthetic apparatus is discussed.     

SppA peptidases: family diversity from heterotrophic bacteria to photoautotrophic eukaryotes

Serine-type SppA peptidases are found in viruses, archaea, eubacteria and in chloroplasts. The family consists of two homologous groups of proteins, designated SppA1 and SppA2, which differ in molecular weight and domain organization. SppA1 is a high molecular weight protein of 70 kDa with two homologous domains with protease signatures. SppA2 represents a half-size SppA1 comprised of only one protease domain. The genomes of most heterotrophic and photosynthetic bacteria encode both, SppA1 and SppA2 proteins, while genome of higher plants, Arabidopsis and rice, encode only one protease, SppA1. An intriguing feature of SppA proteases is their similarity to ClpP proteases in catalytically active regions. SppA functions and gene expression differ between heterotrophic and photosynthetic organisms, in which SppA expression is light-regulated. Apparently, SppA regulation and substrate specificities were modified in photosynthetic organisms and are essential for acclimation of the thylakoid membrane system to light.     

On the taxonomic rank of ciscaucasicus and its relationships with the pygmy wood mouse Sylvaemus uralensis inferred from the mtDNA cytochrome b gene sequence

To specify the taxonomic rank of form ciscaucasoides (independent species Sylvaemus ciscaucasoides, or intraspecific form of pygmy wood mouse, S. uralensis), a 402-bp the mtDNA cytochrome b gene fragment (402 bp) was examined in S. ciscaucasoides individuals from six geographic localities of the Caucasus and Ciscaucasus, (Krasnodar krai and Adygeya Republic) and 17 S. uralensis individuals from seven localities of the Russian Plai (Saratov oblast, Smolensk oblast, Voronezh oblast, Tula oblast, Moscow oblast, and Tver' oblast). For comparison, the cytochrome b gene was partly sequenced in the samples of yellow necked, S. flavicollis (n = 2, Samara oblast), and Caucasian, S. ponticus (n = 6, Krasnodar krai), wood mice. One Mus musculus specimen from Western Europe, whose nucleotide sequences were deposed in the GenBank, was used as intergeneric outgroup. Phylogenetic trees for the forms examined were constructed based on the mtDNA sequence variation and using the neighbor joining and maximum parsimony methods. The network of the cytochrome b haplotypes was also constructed. The level of genetic divergence was evaluated using Kimura's two-parameter algorithm. Based on the data on the sequence variation in a 402-bp mtDNA cytochrome b gene fragment, the hypothesis on the species status of the ciscaucasicus form was. The mean intergroup distances (d) between the geographic groups of S. uralensis varied from 0.0036 to 0.0152. At the same time, the distances between the pygmy wood mice and the group of S.flavicollis-S. ponticus varies in the range from 0.0860 to 0.0935, and the level of intergeneric genetic differentiation (Sylvaemus-Mus) is higher than the latter index (d = 0.142). Ciscaucasoides should be considered as geographic substitution form of S. uralensis. Furthermore, the Caucasian populations of S. uralensis (= ciscaucasoides) were characterized by a threefold lower value of intergroup genetic divergence (d = 0.0062) than the East European populations (d= 0.0179). This finding pointed to some isolation of Caucasian populations of pygmy wood mouse and depletion of their gene pool. However other molecular genetic data (similarity of nucleotide composition and consistence of the levels of intra- and intergroup distances) suggest the absence of geographic subdivision between Caucasian and East European populations ofS. uralensis relative to the molecular marker examined.     

Use of inert gas jets to measure the forces required for mechanical gene transfection

Background

Abnormal blood glucose (BG) concentrations have been associated with increased morbidity and mortality in both critically ill adults and infants. Furthermore, hypoglycaemia and glycaemic variability have both been independently linked to mortality in these patients. Continuous Glucose Monitoring (CGM) devices have the potential to improve detection and diagnosis of these glycaemic abnormalities. However, sensor noise is a trade-off of the high measurement rate and must be managed effectively if CGMs are going to be used to monitor, diagnose and potentially help treat glycaemic abnormalities.

Aim

To develop a tool that will aid clinicians in identifying unusual CGM behaviour and highlight CGM data that potentially need to be interpreted with care.

Methods

CGM data and BG measurements from 50 infants at risk of hypoglycaemia were used. Unusual CGM measurements were classified using a stochastic model based on the kernel density method and historical CGM measurements from the cohort. CGM traces were colour coded with very unusual measurements coloured red, highlighting areas to be interpreted with care. A 5-fold validation of the model was Monte Carlo simulated 25 times to ensure an adequate model fit.

Results

The stochastic model was generated using ~67,000 CGM measurements, spread across the glycaemic range ~2-10?mmol/L. A 5-fold validation showed a good model fit: the model 80% confidence interval (CI) captured 83% of clinical CGM data, the model 90% CI captured 91% of clinical CGM data, and the model 99% CI captured 99% of clinical CGM data. Three patient examples show the stochastic classification method in use with 1) A stable, low variability patient which shows no unusual CGM measurements, 2) A patient with a very sudden, short hypoglycaemic event (classified as unusual), and, 3) A patient with very high, potentially un-physiological, glycaemic variability after day 3 of monitoring (classified as very unusual).

Conclusions

This study has produced a stochastic model and classification method capable of highlighting unusual CGM behaviour. This method has the potential to classify important glycaemic events (e.g. hypoglycaemia) as true clinical events or sensor noise, and to help identify possible sensor degradation. Colour coded CGM traces convey the information quickly and efficiently, while remaining computationally light enough to be used retrospectively or in real-time.