A toolkit for the characterization of CCD cameras for transmission electron microscopy.

Charge-coupled devices (CCD) are nowadays commonly utilized in transmission electron microscopy (TEM) for applications in life sciences. Direct access to digitized images has revolutionized the use of electron microscopy, sparking developments such as automated collection of tomographic data, focal series, random conical tilt pairs and ultralarge single-particle data sets. Nevertheless, for ultrahigh-resolution work photographic plates are often still preferred. In the ideal case, the quality of the recorded image of a vitrified biological sample would solely be determined by the counting statistics of the limited electron dose the sample can withstand before beam-induced alterations dominate. Unfortunately, the image is degraded by the non-ideal point-spread function of the detector, as a result of a scintillator coupled by fibre optics to a CCD, and the addition of several inherent noise components. Different detector manufacturers provide different types of figures of merit when advertising the quality of their detector. It is hard for most laboratories to verify whether all of the anticipated specifications are met. In this report, a set of algorithms is presented to characterize on-axis slow-scan large-area CCD-based TEM detectors. These tools have been added to a publicly available image-processing toolbox for MATLAB. Three in-house CCD cameras were carefully characterized, yielding, among others, statistics for hot and bad pixels, the modulation transfer function, the conversion factor, the effective gain and the detective quantum efficiency. These statistics will aid data-collection strategy programs and provide prior information for quantitative imaging. The relative performance of the characterized detectors is discussed and a comparison is made with similar detectors that are used in the field of X-ray crystallography.

The responses of rat liver glucocorticoid receptors and genes for tyrosine aminotransferase, alpha-2-macroglobulin and gamma-fibrinogen to adrenalectomy-, dexamethasone- and inflammation-induced changes in the levels of glucocorticoids and proinflammatory cytokines.

The responses of liver glucocorticoid receptor (GR) and genes coding for a glucocorticoid-inducible tyrosine aminotransferase (TAT) and two acute-phase proteins (APP) [alpha2-macroglobulin (alpha2-M) and gamma-fibrinogen (Fb)] to changes in glucocorticoid (GC) and proinflammatory (AP) cytokine contents have been examined in rats after single or combined treatments with turpentine oil, dexamethasone (Dex) and adrenalectomy. Activation of two APP genes in turpentine-induced inflammation was accompanied by an increase in the level of GR mRNA and a preferential translocation of GR-GC complexes to the nucleoplasm, while the expression of TAT remained unaltered. Dex alone caused a decrease in the levels of GR and Fb mRNAs, activation of TAT and alpha2-M genes, a decrease in the affinity of hormone binding sites and redistribution of translocated GR-Dex complexes within the nuclei. Inflammation potentiated the effect which Dex alone exerted on the GR content and the number of GR binding sites but counteracted its influence on the affinity of GR binding sites and nuclear distribution of GR-Dex complexes. Adrenalectomy promoted a fall in TAT mRNA, no changes in the GR and Fb mRNA, a decrease in the affinity of GR hormone binding sites and redistribution of GR-hormone complexes within the nuclei. The AP cytokines released in response to inflammation exerted a counteracting effect on the adrenalectomy-induced changes in the affinity of hormone binding sites and nuclear distribution of GR-hormone complexes. They potentiated a fall of TAT mRNA but promoted full expression of the Fb gene. These results argue strongly for the influence of AP cytokines on the functional state of the GR and GC signaling pathways.

Glucocorticoid receptors in lymphocytes and stability of kidney graft function.

The glucocorticoid receptors in lymphocytes of patients treated with glucocorticoids after kidney transplantation have been studied in order to determine whether abnormalities in corticosteroid binding and trans-activation of steroid-receptor complexes, i.e., their translocation into nuclei, may contribute to the resistance of patients to glucocorticoid therapy. The patients were divided into two groups, according to graft stability: patients with stable graft function and those with chronic allograft rejection. The study revealed changes in both level and binding affinity of glucocorticoid receptors in peripheral blood lymphocytes from patients with chronic graft rejection, compared with control level, as well as with values of patients with stable graft function. These data indicate that sensitivity to glucocorticoids depends, at least in part, on the alterations of glucocorticoid receptors. The receptor translocation into nuclei indicates that unknown post-receptor events might also be involved in glucocorticoid resistance that seriously impair successive glucocorticoid therapy after organ transplantation. Further examination of glucocorticoid receptors in cases of organ transplantation seems warranted.

[Relation between dental plaque fluoride content and caries]. / Sadrzaj fluorida u zubnim plakama i zubni kvar.

The purpose of this study was to investigate the effect of plaque fluoride content on dental caries in children aged 12 years, from the area with minimal (Valjevo) and optimal and/or higher fluoride concentrations (Vranjska Banja) in drinking water. The caries prevalence was determined by the standardized epidemiological method. The fluoride concentration in dental plaques was measured with the Ion-selective electrode. The fluoride content in the plaque of children from Valjevo (7.8 ppm) was significantly smaller than in children from Vranjska Banja (36.5 ppm). In 12-year old individuals with the lowest fluoride concentrations in the plaque the greatest values of the caries prevalence were found. The increase in plaque fluoride content provoked the decrease in caries prevalence. The lowest values of caries index were found in children with 21 to 30 ppF in dental plaque.

[Adentol (natural sweetener) and caries prevention]. / Adentol (prirodni zssladivac) prevencija karijesa.

Numerous epidemiological, experimental and clinical studies have established, without doubt, the correlation between the consumption of dietary sugars and caries prevalence. The increase of the sugar consumption in Yugoslavia is in direct correlation with caries activity in children. One of the aims of preventive programmes is to improve the diet habits through the use of non-cariogenic sugar substitutes. Adentol is a hydrogenated glucose syrup obtained from the enzymic hydrolysis of corn starch, made by D.P.,"HPK" Bosanska Dubica-Yugoslavia. Its chemical content is very similar to that of Lycasin 80/55 (Roquette Frères-France). Published data on its behaviour in acid production in vitro and in dental plaques, its effect on the oral microorganisms and the process of remineralization of initial caries lesions, suggest that hydrogenated glucose syrup (Lycasin, Adentol) is less fermentable in oral cavity and without cariogenic properties. Substitution of dietary sugars by Adentol in confectionery and syrup medicines is likely to be of significant benefit to dental health.

[Relation between plaque index and gingival cell infiltrate in experimental animals]. / Odnos plak indeksa i celijskog infiltrata gingive eksperimentalnih zivotinja.

The aim of this study was to determine the relation between plaque and gingival cell infiltrates in highly imbreaded laboratory rats during experimentally provoked gingivitis. In this experiment 24 Lewis rats, aged 1-3 months, were used. From the zero day of inflammation plaque was scored by Sillnes and Löe index, while the presence of gingival cell infiltrate was determined with the stereological method. The results point out that the elder animals manifested early plaque accumulation, while the young group of animals presented a more intensive gingival cell infiltration. On the basis of the obtained results it can be concluded that within the equal amounts of plaque the young animals had a more intensive gingival cell infiltration as the result of distincet defensive reaction to the presence of microbial antigens.

Oral health in SFR Yugoslavia in 1986.

A pilot oral health epidemiological survey using WHO assessment forms was conducted in Yugoslavia in the year 1986. The study population consisted of 2600 persons aged 6, 12, 15, 18, 35-44, and over 65 yr. The survey included 22 towns (11 developed and 11 underdeveloped) in the six Republics and two Provinces of Yugoslavia. The results showed the prevalence of dental caries in the Yugoslav population to be very high (98.7% in 12-yr-olds). The mean decayed, missing, and filled teeth (DMF) scores were as follows: 6.1 at age 12 yr, 9.6 at age 15, 10.9 at age 18, 18.0 at age 35-44, and 28.0 in persons aged over 65 yr. Assessment of the periodontal status showed calculus to be the predominant disorder in the age groups 18 and 35-44 yr, while loss of sextants prevailed in persons aged over 65 yr.