Risk factors for suicide in the Israeli army between the years 1992-2012: A case-control study.

OBJECTIVE: Young age, availability of weapons, and stressful life events, increase the risk of suicide. The aim of the present study was to assess additional risk factors for suicide in the Israeli army. METHODS: We conducted a case-control study, to assess risk factors for suicide. The cases comprised soldiers who died by suicide during their military service (n=462; 0.039% of all soldiers in the cohort). The control group consisted of soldiers who did not commit suicide but were in active service during the investigated period (n=1,170,895; 99.96%). Predictor variables, including socio-demographic and psychiatric diagnoses, were considered. RESULTS: Using a Generalized Linear Model with a Binary Logistic dependent variable to predict suicide, while controlling the effect of intervening variables, we found the following variables enhanced the risk for committing suicide: male (RR=6.703; P<0.001), country of origin: Ethiopia (RR=4.555; P=0.014), low socioeconomic status (RR=1.448; P=0.016) and low adjustment difficulties (RR=2.324; P<0.001). In addition, we found that in males only, Cluster B Personality Disorder (RR=2.548; P=0.027), low (RR=1.657; P=0.002), to average motivation to serve in a combat unit (RR=1.322; P=0.046) increased the risk for suicide. CONCLUSIONS: IDF Soldiers bearing a psychiatric diagnosis or severe adjustment difficulties remained tightly monitored through their military service, and were found to be at a lower risk for suicide. However, those enlisted with mild (low) difficulties, were found to be at greater risk for suicide, as well as soldiers whose country of origin is Ethiopia. Suicide prevention program should focus on monitoring soldiers with these risk factors, together with soldiers' guidance regarding help seeking and de-stigmatizing suicide.

The influence of model drugs on the preparation of pellets by extrusion/spheronization: II. Spheronization parameters.

Five drug-models, 4-parahydroxybenzoic acid (4HBA), methyl (MBA), propyl (PBA) and butyl (BBA) paraben and propyl gallate (PG), all of similar chemical nature, were mixed in different proportions (50-73.7%) with microcrystalline cellulose (MCC) (26.3-50%) plus various levels of water (26.9-50.0%). The wet powder mass was extruded and spheronized under standard conditions. The pellets produced were evaluated in terms of their median diameter, their modal size range, the % within a given size range (0.7-1.7 mm) and their shape factor. For the majority of formulations, all drug models, except 4HBA, produced pellets. This material only had two combinations of excipients that produced acceptable pellets. For all the model drugs, two combinations of formulations could be identified; (1) a combination, which produced pellets from all the model drugs and (2) a combination, which was too wet to produce pellets with any of the model drugs. Between these two extremes, whether pellets could be made and their quality varied with the model drug. Cluster analysis was able to divide the formulations into 4 clusters. In cluster 1 all the model drugs produced pellets except 4HBA; in cluster 2 all drugs produced pellets except MBA; in cluster3, pellets were produced with PBA, BBA and PG while MBA produced agglomerates and 4HBA was too dry; in cluster 4, MBA and BBA produced pellets, PBA produced agglomerates while 4HBA was too dry to pelletise and PG too dry to extrude. The five drug models showed different relationships between the median pellet size and drug-load and initial water content in the formulation. Cluster analysis indicated that, the level of water and type of model drug were the most significant factors in determining the pellet size. Three clusters could be identified, but the response to water content was drug dependent. It was not possible to identify a relationship between the force required to extrude the wet mass and the ability to produce good pellets nor their median size. All the products, which could be classified as good pellets, when produced, had a shape factor that can be considered to be indicative of a spherical shape. The most consistent material, in terms of spheronization, as represented by median diameter, size range and roundness, was propyl gallate (PG), which throughout all the formulations produced an almost constant value for shape factor and median pellet size, which in the majority of cases fell within a limited pellet size.

The influence of type and quantity of model drug on the extrusion/spheronization of mixtures with microcrystalline cellulose. I. Extrusion parameters.

Five model drugs, (methyl, propyl and butyl paraben, 4-hydroxybenzoic acid and propyl gallate), similar in their chemical structure were mixed with microcrystalline cellulose and water in different proportions and forced through a ram extruder. The overall water movement was measured by the difference between the initial water in the formulation and the water content in the plug remaining after extrusion was completed. The differences in theoretical and practical volume occupancy of the materials inside the barrel were calculated to look for trapped air inside the barrel. The steady-state extrusion force for each formulation was recorded. All five materials demonstrated differences in behaviour during extrusion. The relationship between each of the three properties measured and both the drug-load and initial water content was examined, to establish the potential relationship that existed between the differences due to the drug models. The five drug models were divided into two sub-groups, when examining the way that they underwent extrusion. Methyl, propyl and butyl paraben formed one group while 4-hydroxybenzoic acid and propyl gallate formed the other group. Within the former group the relationship between steady-state extrusion force and the percentage of drug and water present tended to be lower than those in the latter group. For the former group these relationships were non-linear.

Measuring the water retention capacities (MRC) of different microcrystalline cellulose grades.

The ability of various types of microcrystalline cellulose (MCC) to hold water when subjected to an applied force has been assessed by a centrifuge technique. By considering the final percent of water retained after a standard centrifugation, as a function of the initial water content, a moisture retention capacity (MRC) can be determined. Statistical analysis of the results identified that it was possible to divide the nine samples of MCC into six sub-sets in terms of final moisture content retained. Those types which contained added polymer had by far the highest water level remaining. In terms of the MRC value, statistical analysis again sub-divided the celluloses into six sub-sets, although different from those for the final water content. Again those types containing added polymer gave much higher MRC values. As experiments were carried out with initial water/MCC ratios of different levels, statistical analysis of the influence of initial water content on the MRC values was undertaken with each type of MCC. The results showed a varying dependence on initial water level with the different types of cellulose. To provide a value of MRC which characterised the cellulose, the maximum value of MRC at the lowest initial water level was identified. Samples of MCC with low values of MRC have been shown previously to require less water for processing by extrusion/spheronization, while celluloses with a high MRC value appear better for the limitation of water movement during the process of extrusion/spheronization. The water retention must, however, also be considered in association with the rheological properties of the wet powder mass. Thus, while the Avicel RC591 had the highest MRC value, its rheological properties are so that the production of pellets with such a type can be less effective than with other types of MCC.

Translesion replication by DNA polymerase delta depends on processivity accessory proteins and differs in specificity from DNA polymerase beta.

Mutations caused by DNA damage lead to the development of cancer. The critical step in the formation of these mutations is the replication of unrepaired lesions in DNA by DNA polymerases, a process termed translesion replication. Using a newly developed method for preparation of gapped plasmids, containing a site-specific synthetic abasic site, we analyzed translesion replication with purified mammalian DNA polymerases delta and beta. DNA polymerase delta was found to be unable to replicate through the abasic site. Addition of the sliding DNA clamp PCNA, the clamp loader RFC, and ATP caused a drastic 30-fold increase in translesion replication. Thus, similar to Escherichia coli DNA polymerase III, the processivity accessory proteins enable DNA polymerase delta to bypass blocking lesions. Under comparable conditions, DNA polymerase beta was unable to bypass the abasic site, unless its concentration was greatly increased. Analysis of translesion replication products revealed a marked difference in the specificity of bypass: whereas 90% of bypass events by DNA polymerase delta holoenzyme involved insertion of a dAMP residue opposite the abasic site, DNA polymerase beta tended to skip over the abasic site, producing mainly minus frameshifts (73%). The significance of these results for in vivo translesion replication is discussed.

Highly mutagenic replication by DNA polymerase V (UmuC) provides a mechanistic basis for SOS untargeted mutagenesis.

When challenged by DNA-damaging agents, Escherichia coli cells respond by inducing the SOS stress response, which leads to an increase in mutation frequency by two mechanisms: translesion replication, a process that causes mutations because of misinsertion opposite the lesions, and an inducible mutator activity, which acts at undamaged sites. Here we report that DNA polymerase V (pol V; UmuC), which previously has been shown to be a lesion-bypass DNA polymerase, was highly mutagenic during in vitro gap-filling replication of a gapped plasmid carrying the cro reporter gene. This reaction required, in addition to pol V, UmuD', RecA, and single-stranded DNA (ssDNA)-binding protein. pol V produced point mutations at a frequency of 2.1 x 10(-4) per nucleotide (2.1% per cro gene), 41-fold higher than DNA polymerase III holoenzyme. The mutational spectrum of pol V was dominated by transversions (53%), which were formed at a frequency of 1.3 x 10(-4) per nucleotide (1. 1% per cro gene), 74-fold higher than with pol III holoenzyme. The prevalence of transversions and the protein requirements of this system are similar to those of in vivo untargeted mutagenesis (SOS mutator activity). This finding suggests that replication by pol V, in the presence of UmuD', RecA, and ssDNA-binding protein, is the basis of chromosomal SOS untargeted mutagenesis.

Measuring water distribution in extrudates using magnetic resonance imaging (MRI).

Magnetic resonance imaging (MRI) has been applied to the evaluation of the distribution of water in extrudates produced by extruding pastes. Two model drugs similar in chemical structure were mixed with microcrystalline cellulose (MCC) and with two different amounts of water and extruded at two different extrusion speeds using a ram extruder. Extrudates were collected during the steady-state stage of the extrusion profile and were analysed for the water distribution using MRI. The percolation threshold for each sample was calculated to evaluate the degree of water structure within the sample. The water distribution inside the extrudates was surprisingly uniform. The extrudates produced using the faster extrusion speed had a significant lower percolation threshold, which suggests the existence of a greater water structure in the extrudates. A significant correlation was found between the percolation threshold and the extrusion force, which had been used to provide the extrudates.

A centrifuge technique for the evaluation of the extent of water movement in wet powder masses.

A centrifuge method has been applied to the assessment of water retention in pharmaceutical powders. Five drug models and microcrystalline cellulose (MCC) were each mixed with different amounts of water and centrifuged at different speeds. The amount of water retained by the wet mass was evaluated by drying the powders to constant weight. Binary mixtures of each of the five model drugs, MCC and water were also processed in the same way. From the amount of water extracted the moisture retention capacity (MRC) was calculated. The MCC retained water more strongly than the different drug models over a wider range of initial water contents. The five drug models, although similar in their chemical structure, were divided into two groups, in terms of their MRC values. 4-HBA and propyl gallate recorded higher MRC values than methyl, propyl and butyl paraben. For the drug models mixed with MCC, the MRC values recorded were similar, though it was still possible to divide the drugs into the two subgroups. A correlation between the MRC value recorded for the different systems and the hydrogen bonding solubility component was found. The application of different centrifuge speeds indicated that within the same material there were different mechanisms of water retention.

Magnetic resonance imaging (MRI) as a method to investigate movement of water during the extrusion of pastes.

PURPOSE: To assess the potential of Magnetic Resonance Imaging (MRI) as a method of detecting water movement during the extrusion of pastes. METHODS: Plug samples were made from mixtures of model materials and microcrystalline cellulose with two water contents at two different ram speeds to simulate ram extrusion. The extrusion process was stopped at different stages and analyzed for water distribution using MRI to assess the influence of water content and the speed of ram on water movement as the extrusion process progresses. RESULTS: Two types of water movement were detected: vertical and radial. When extruding at the faster ram speed, water moved predominantly in the vertical direction, whereas when extruding at a slower ram speed it moved predominantly in the radial direction. At the beginning of the extrusion process a greater water movement in the wetter formulations was observed. CONCLUSIONS: MRI appears to be a useful approach to non-invasive water mapping, and is expected to contribute towards a greater understanding of the role of water in the extrusion of pastes.

Prognostic factors in non-metastatic limb osteosarcoma: A 20-year experience of one center.

The purpose of this study was to evaluate the prognostic significance of variables in osteosarcoma. We performed a retrospective analysis of 35 patients with non-metastatic limb osteosarcoma that were treated between 1973 and 1994. The following variables were evaluated: age, sex, ethnic group, tumor histology and primary site, alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels at diagnosis, treatment regimen, and the histologic response to treatment. Three variables showed significant correlation with prognosis: i) histologic response to preoperative treatment. Disease-free survival (DFS) was 89% in patients with grade III-IV histologic response after a median follow-up (MFU) of 64 months, 67% in patients with grade II after an MFU of 64 months, the patients with grade I response died within 15 months (p<0.0001); ii) treatment regimen. DFS was 83% after an MFU of 42 months, 62% after an MFU of 82 months, and 30% after an MFU of 177 months in patients treated by the 90's, 80's, and 70's protocols, respectively (p<0.05); iii) corrected ALP (cALP) levels at diagnosis. DFS was 78% after an MFU of 88 months in patients with cALP levels <200, and 32% after an MFU of 56 months in patients with cALP levels >200 (p=0.01). Low ALP levels, good histologic response to preoperative chemotherapy, and the new therapeutic regimen correlated with good prognosis in patients with osteosarcoma.

Water movement evaluation during extrusion of wet powder masses by collecting extrudate fractions.

Water is normally the liquid of choice in extrusion/spheronisation systems. Its behaviour during the process is crucial to its success. In most extrusion formulations water moves under the pressures involved. It is important to understand how to control and limit water movement, and to understand its consequences. Five drug models were mixed with microcrystalline cellulose and with three different ratios of water and extruded at two different speeds using a ram extruder. Whilst extruding, the extrudates were collected to small fractions and dried to constant weight. Different parameters were calculated to quantify the extent of water movement that occurred. The same formulations were also extruded and than spheronised to pellets, for which size and shape factor were measured. The correlation between water level and extrusion force at the same given time was calculated. It was found that at the faster speed and in the wettest formulation there was less water movement. A significant correlation was found between extrusion force and water going through the die. The extrusion/spheronisation technique was found to be tolerant to some extent of water movement during the extrusion process. Nevertheless, excessive water movement is not appropriate.

Analysis of unassisted translesion replication by the DNA polymerase III holoenzyme.

DNA damage-induced mutations are formed when damaged nucleotides present in single-stranded DNA are replicated. We have developed a new method for the preparation of gapped plasmids containing site-specific damaged nucleotides, as model DNA substrates for translesion replication. Using these substrates, we show that the DNA polymerase III holoenzyme from Escherichia coli can bypass a synthetic abasic site analogue with high efficiency (30% bypass in 16 min), unassisted by other proteins. The theta and tau subunits of the polymerase were not essential for bypass. No bypass was observed when the enzyme was assayed on a synthetic 60-mer oligonucleotide carrying the same lesion, and bypass on a linear gapped plasmid was 3-4-fold slower than on a circular gapped plasmid. There was no difference in the bypass when standing-start and running-start replication were compared. A comparison of translesion replication by DNA polymerase I, DNA polymerase II, the DNA polymerase III core, and the DNA polymerase III holoenzyme clearly showed that the DNA polymerase III holoenzyme was by far the most effective in performing translesion replication. This was not only due to the high processivity of the pol III holoenzyme, because increasing the processivity of pol II by adding the gamma complex and beta subunit, did not increase bypass. These results support the model that SOS regulation was imposed on a fundamentally constitutive translesion replication reaction to achieve tight control of mutagenesis.

The beta subunit sliding DNA clamp is responsible for unassisted mutagenic translesion replication by DNA polymerase III holoenzyme.

The replication of damaged nucleotides that have escaped DNA repair leads to the formation of mutations caused by misincorporation opposite the lesion. In Escherichia coli, this process is under tight regulation of the SOS stress response and is carried out by DNA polymerase III in a process that involves also the RecA, UmuD' and UmuC proteins. We have shown that DNA polymerase III holoenzyme is able to replicate, unassisted, through a synthetic abasic site in a gapped duplex plasmid. Here, we show that DNA polymerase III*, a subassembly of DNA polymerase III holoenzyme lacking the beta subunit, is blocked very effectively by the synthetic abasic site in the same DNA substrate. Addition of the beta subunit caused a dramatic increase of at least 28-fold in the ability of the polymerase to perform translesion replication, reaching 52% bypass in 5 min. When the ssDNA region in the gapped plasmid was extended from 22 nucleotides to 350 nucleotides, translesion replication still depended on the beta subunit, but it was reduced by 80%. DNA sequence analysis of translesion replication products revealed mostly -1 frameshifts. This mutation type is changed to base substitution by the addition of UmuD', UmuC, and RecA, as demonstrated in a reconstituted SOS translesion replication reaction. These results indicate that the beta subunit sliding DNA clamp is the major determinant in the ability of DNA polymerase III holoenzyme to perform unassisted translesion replication and that this unassisted bypass produces primarily frameshifts.

The mutagenesis proteins UmuD' and UmuC prevent lethal frameshifts while increasing base substitution mutations.

Error-prone DNA repair consists of replicative filling-in of DNA gaps carrying lesions. We have reconstituted E. coli SOS error-prone repair using purified DNA polymerase III holoenzyme, SSB, RecA, UmuD', a UmuC fusion protein, and a gap lesion plasmid. In the absence of UmuDC, or without SOS induction, replication skips over the lesion, forming mostly one-nucleotide deletions. These cause translational frameshifts that usually inactivate genes. UmuD' and UmuC, in the presence of RecA and SSB, stimulate translesion replication and change its mutagenic specificity such that deletions are prevented and base substitutions are increased. This results in mutagenic but nondetrimental gap repair and provides an effective mechanism for generating genetic variation in bacteria adapting to environmental stress.

Reconstitution of repair-gap UV mutagenesis with purified proteins from Escherichia coli: a role for DNA polymerases III and II.

Using a cell-free system for UV mutagenesis, we have previously demonstrated the existence of a mutagenic pathway associated with nucleotide-excision repair gaps. Here, we report that this pathway can be reconstituted by using six purified proteins: UvrA, UvrB, UvrC, DNA helicase II, DNA polymerase III core, and DNA ligase. This establishes the minimal requirements for repair-gap UV mutagenesis. DNA polymerase II could replace DNA polymerase III, although less effectively, whereas DNA polymerase I, the major repair polymerase, could not. DNA sequence analysis of mutations generated in the in vitro reaction revealed a spectrum typical of mutations targeted to UV lesions. These observations suggest that repair-gap UV mutagenesis is performed by DNA polymerase III, and to a lesser extent by DNA polymerase II, by filling-in of a rare class of excision gaps that contain UV lesions.