Theoretical investigations of prostatic acid phosphatase

The phosphotyrosyl protein phosphatase activity of prostatic acid phosphatase (PAP) has been well established. It has also been suggested that PAP partly regulates the activity of growth factor receptors by dephosphorylating the autophosphorylysable tyrosines in them. We studied the binding of the peptides from epidermal growth factor receptor (EGFR) and its homolog (ErbB-2), corresponding to their autophosphorylation sites, to PAP using theoretical modeling and molecular dynamics (MD) simulation methods. Nine different peptides, each with a phosphotyrosine residue, were docked on human PAP. The binding energies of these peptide-PAP complexes were calculated theoretically and compared to experimentally obtained affinities. The peptide Ace--DNLpYYWD--NH2 from ErbB-2(1197-1203) showed the most favorable free energy of binding when estimated theoretically. The results demonstrate that the presence of another tyrosine residue proximate to C-terminal of autophosphorylysable Tyr enhances the binding affinity considerably. The presence of a bulky group instead prevents the binding, as is observed in case of peptide Ace--NLYpYWDQ--NH2 which failed to bind, both in theoretical calculations and experiments. Thus we demonstarted that PAP could potentially bind to EGFR and Erbb-2 and dephosphorylate them. Thus it could be involved in the regulation of the function of such receptors. In addition, complexes of a peptide from AngiotensinII and phosphotyrosine(pY) with human PAP were also modeled. The effects of different protonation states of the titratable active site residues on ligand (pY) binding have also been investigated. For a favorable binding His12 and Asp258 should be neutral, His257 should be positively charged and the phosphate group of the ligand should be in PO(4) (3-) state. Furthermore, the analysis of protein motion as observed during simulations suggests the loop-loop contact in the PAP dimer to be of importance in cooperativity.     

Impact of updating the non-radiation parameters in the ICRP 103 detriment model

The radiation detriment in ICRP 103 is defined as the product of the organ-specific risk coefficient and the damage that may be associated with a cancer type or hereditary effect. This is used to indicate a weighted risk according to the radiation sensitivity of different organs and the severity of damage that may possibly arise. While the risk refers to radiation exposure parameters, the extent of damage is independent of radiation. The parameters that are not affected by radiation are lethality, impairment of quality of life, and reduced life expectancy, which are considered as quantities associated with the severity of disease or damage. The damage and thus the detriment appear to be mostly affected by lethality, which is the quotient of the age-standardized mortality rate to the incidence rate. The analysis of the detriment presented in this paper focuses on the influence of the lethality on the detriment from 1980 to 2012 in the USA and Germany. While the lethality in this period covering more than three decades has decreased approximately linearly by 30% (both USA and Germany), within the same period the detriment declined only by 13% in the USA and by 15% in Germany. If only based on these two countries, an update on the detriment parameters with reference to 2007, when ICRP 103 was released, would result in a reduced weighted risk, i.e. the radiation detriment would be reduced by 10 to 15% from originally 5.7% per Sv for the whole population to roughly 5% per Sv.     

High-affinity binding of laminin by Helicobacter pylori: Evidence for a lectin-like interaction

Abstract Laminin, the major glycoprotein of basement membranes, was shown to be bound by the human gastric pathogen Helicobacter pylori . Binding of ¹²⁵I-laminin by strain 17874 was time-dependent, specific and saturable. Scatchard analysis of specific binding indicated about 2000 binding sites per cell with a dissociation constant of 8.5 pM. Treatment of the cells by heat (80°) and with proteolytic enzymes drastically reduced laminin binding, suggesting that the laminin receptors are surface proteins. Some highly glycosylated glycoproteins inhibited laminin binding by 50%. Furthermore, N -acetylneuraminyllactose decreased laminin binding by 70% and neuraminidase treatment of laminin by 50%, while a recombinant B1 chain of laminin, containing high-mannose type oligosaccharides, inhibited binding by only 25%. This suggests that terminal sialic acids on laminin compete for a specific sugar binding protein(s) on H. pylori cells.     

Developmental changes in Hl histones from bovine liver

The liver histones of calf embryos, calves and adult cows were analyzed by use of a high-resolution sodium dodecyl sulfate slab gel electrophoresis. The results show both qualitative and quantitative changes in the Hl histones. The Hl histone of the young embryos appeared as two components, that of the embryo at seven months of age as three components and that of the older embryos, as also that of the calves and adult cows, as four components. In addition, the relative proportion of the Hl histones increased during the whole ontogeny.     

Validation of Morphometric Analyses of Small-Intestinal Biopsy Readouts in Celiac Disease

Background

Assessment of the gluten-induced small-intestinal mucosal injury remains the cornerstone of celiac disease diagnosis. Usually the injury is evaluated using grouped classifications (e.g. Marsh groups), but this is often too imprecise and ignores minor but significant changes in the mucosa. Consequently, there is a need for validated continuous variables in everyday practice and in academic and pharmacological research.

Methods

We studied the performance of our standard operating procedure (SOP) on 93 selected biopsy specimens from adult celiac disease patients and non-celiac disease controls. The specimens, which comprised different grades of gluten-induced mucosal injury, were evaluated by morphometric measurements. Specimens with tangential cutting resulting from poorly oriented biopsies were included. Two accredited evaluators performed the measurements in blinded fashion. The intraobserver and interobserver variations for villus height and crypt depth ratio (VH:CrD) and densities of intraepithelial lymphocytes (IELs) were analyzed by the Bland-Altman method and intraclass correlation.

Results

Unevaluable biopsies according to our SOP were correctly identified. The intraobserver analysis of VH:CrD showed a mean difference of 0.087 with limits of agreement from −0.398 to 0.224; the standard deviation (SD) was 0.159. The mean difference in interobserver analysis was 0.070, limits of agreement −0.516 to 0.375, and SD 0.227. The intraclass correlation coefficient in intraobserver variation was 0.983 and that in interobserver variation 0.978. CD3⁺ IEL density countings in the paraffin-embedded and frozen biopsies showed SDs of 17.1% and 16.5%; the intraclass correlation coefficients were 0.961 and 0.956, respectively.

Conclusions

Using our SOP, quantitative, reliable and reproducible morphometric results can be obtained on duodenal biopsy specimens with different grades of gluten-induced injury. Clinically significant changes were defined according to the error margins (2SD) of the analyses in VH:CrD as 0.4 and in CD3⁺-stained IELs as 30%.     

Salivary flow rate and risk of malnutrition – a study among dentate,community‐dwelling older people

doi: 10.1111/j.1741‐2358.2012.00679.x Salivary flow rate and risk of malnutrition – a study among dentate, community‐dwelling older people Objective: To analyse the relation between unstimulated and stimulated salivary secretion and the risk of malnutrition among home‐dwelling elderly people. Background: Saliva has an important role in eating. Despite this, there are only a few studies on the role of salivary secretion in the development of malnutrition among elderly people. Materials and methods: The study population consisted of 157 subjects aged 75 or older. This was a part of GeMS study carried out in Kuopio, in eastern Finland. The data used in this study were collected by means of interviews and geriatric and oral clinical examinations. The risk of malnutrition was measured using the Mini Nutritional Assessment Short‐Form. Logistic regression models were used to estimate odds ratios (OR) and their 95% Confidence Intervals (CI). Results: Subjects with a low unstimulated salivary flow rate (<0.1 ml/min) or stimulated salivary flow rate (<1.0 ml/min) had no statistically significant increase in risk of malnutrition, OR: 1.3, CI: 0.5–3.9, OR: 1.5, CI: 0.5–4.2, respectively, when compared with those with a normal unstimulated and stimulated salivary flow rate. Conclusion: Our results do not support the concept that low salivary secretion is an important risk factor for malnutrition among community‐dwelling elders.     

Dementia and oral health among subjects aged 75 years or older

doi: 10.1111/j.1741‐2358.2010.00396.x Dementia and oral health among subjects aged 75 years or older Objective: To study the association between diagnosed dementia and oral health, focusing on the type of dementia, among an elderly population aged 75 years or older. Background: Elderly people with dementia are at risk from oral diseases, but to date, only a few studies have analysed the association between type of dementia and oral health, and their results are inconclusive. Materials and methods: This cross‐sectional study is based on the Geriatric multi‐disciplinary strategy (Gems) study that included 76 demented and 278 non‐demented subjects. The data were collected by means of an interview and an oral clinical examination. The type of dementia was diagnosed according to DSM‐IV criteria. Poisson’s and logistic regression models were used to determine relative risks (RR), odds ratios (OR) and 95% confidence limits (CI). Results: Our results showed that patients with Alzheimer’s disease and those with other types of dementia had an increased likelihood of having carious teeth, teeth with deep periodontal pockets, and poor oral and denture hygiene, compared with non‐demented persons. The results showed that the type of dementia does not seem to be an essential determinant of oral health. Conclusions: Among the elderly aged 75 years or older, patients with Alzheimer’s disease or other types of dementia are at increased risk of poor oral health and poor oral hygiene.     

ESCRT components ISTL1 andLIP5 are required for tapetal function and pollen viability

Pollen wall assembly is crucial for pollen development and plant fertility. The durable biopolymer sporopollenin and the constituents of the tryphine coat are delivered to developing pollen grains by the highly coordinated secretory activity of the surrounding tapetal cells. The role of membrane trafficking in this process, however, is largely unknown. In this study, we used Arabidopsis thaliana to characterize the role of two late-acting endosomal sorting complex required for transport (ESCRT) components, ISTL1 and LIP5, in tapetal function. Plants lacking ISTL1 and LIP5 form pollen with aberrant exine patterns, leading to partial pollen lethality. We found that ISTL1 and LIP5 are required for exocytosis of plasma membrane and secreted proteins in the tapetal cells at the free microspore stage, contributing to pollen wall development and tryphine deposition. Whereas the ESCRT machinery is well known for its role in endosomal trafficking, the function of ISTL1 and LIP5 in exocytosis is not a typical ESCRT function. The istl1 lip5 double mutants also show reduced intralumenal vesicle concatenation in multivesicular endosomes in both tapetal cells and developing pollen grains as well as morphological defects in early endosomes/trans-Golgi networks, suggesting that late ESCRT components function in the early endosomal pathway and exocytosis.

Endosomal sorting complex required for transport proteins ISTL1 and LIP5 are required for exocytosis of both plasma membrane and secreted proteins in tapetal cells during microspore formation.