The amount of platelet-bound albumin parallels the amount of IgG on washed platelets from patients with immune thrombocytopenia

The biologic relevance of the increased platelet-associated IgG (PAIgG) on platelets from patients with idiopathic thrombocytopenic purpura (ITP) is unclear. Platelets from ITP patients are often larger than normal, and it is possible that the increased IgG is not specific but passively related to platelet size. The measurement of platelet-bound albumin could provide information concerning the specificity of the platelet-bound IgG, since albumin, like IgG, is a plasma protein, but unlike IgG, is not an active participant in immunologic reactions. Albumin is also a normal constituent of platelet membrane, and increased platelet albumin could indicate an increased platelet mass. Platelet-bound albumin, IgG, and total platelet protein were measured on both intact and disrupted platelets from healthy individuals (n = 25) and patients with ITP (n = 21). Platelet IgG and albumin were measured in an immunoradiometric assay using intact antisera and F(ab')2 fragments prepared from the same antisera. There was no relationship between platelet-bound IgG or albumin, and platelet size measured by either platelet protein or platelet volume, (r less than 0.3 for all interactions). In contrast, there was a significant correlation between platelet-bound albumin and platelet-bound IgG (r = 0.7, n = 21, p less than 0.001). Those patients with elevated platelet PAIgG also had elevated platelet albumin, and this relationship was irrespective of the total platelet protein content or mean platelet volume. It is possible that the increased platelet-bound IgG in ITP reflects an increase in platelet surface area or contaminating platelet fragments that are not manifested as an increase in platelet volume or total platelet protein. Alternatively, a platelet membrane abnormality may occur in ITP that results in the uptake of significant amounts of plasma proteins. Either possibility implies that not all of the IgG on platelets from patients with ITP is pathologic IgG.     

Further studies of the secretory pathway in thrombin-stimulated human platelets

The pathway followed by secretory products stored in platelet alpha granules during the release reaction remains controversial. Tannic acid has been used in the present study as an electron-dense stain to follow the secretory process in thrombin-stimulated platelets. Preliminary experiments demonstrated that tannic acid precipitates fibrinogen, and binds osmium tetroxide to fibrinogen and fibrin strands. Examination of platelets fixed at short intervals after exposure to thrombin and incubated in solutions containing tannic acid revealed electron-dense deposits of osmium not apparent in resting platelets. Granules and lumina of channels making up the open canalicular system (OCS) were unstained in discoid cells. However, exposure to thrombin at concentrations of 1 to 5 U/mL for thirty seconds or more resulted in intense staining of alpha granules by osmium. Some granules communicated directly with dilated channels of the OCS, and several were frequently connected to the same canaliculus. The electron-dense substance in swollen granules and channels appeared to be in the process of extrusion through narrow or dilated openings of the OCS onto the platelet surface. Granule-to-granule fusion and formation of sealed vacuoles of fused granule products unstained by tannic acid-osmium were not observed. The findings support the concept that secretion by stimulated human platelets results from development of direct communications between granules and channels of the OCS and subsequent extrusion of products through channel pores to the surrounding medium.     

Selective Blockade of Dopamine D3 Receptors Enhances while D2 Receptor Antagonism Impairs Social Novelty Discrimination and Novel Object Recognition in Rats: A Key Role for the Prefrontal Cortex

Dopamine D₃ receptor antagonists exert pro-cognitive effects in both rodents and primates. Accordingly, this study compared the roles of dopamine D₃ vs D₂ receptors in social novelty discrimination (SND), which relies on olfactory cues, and novel object recognition (NOR), a visual-recognition task. The dopamine D₃ receptor antagonist, {"type":"entrez-protein","attrs":{"text":"S33084","term_id":"420474","term_text":"pir||S33084"}}S33084 (0.04–0.63 mg/kg), caused a dose-related reversal of delay-dependent impairment in both SND and NOR procedures in adult rats. Furthermore, mice genetically deficient in dopamine D₃ receptors displayed enhanced discrimination in the SND task compared with wild-type controls. In contrast, acute treatment with the preferential dopamine D₂ receptor antagonist, L741,626 (0.16–5.0 mg/kg), or with the dopamine D₃ agonist, PD128,907 (0.63–40 μg/kg), caused a dose-related impairment in performance in rats in both tasks after a short inter-trial delay. Bilateral microinjection of {"type":"entrez-protein","attrs":{"text":"S33084","term_id":"420474","term_text":"pir||S33084"}}S33084 (2.5 μg/side) into the prefrontal cortex (PFC) of rats increased SND and caused a dose-related (0.63–2.5 μg/side) improvement in NOR, while intra-striatal injection (2.5 μg/side) had no effect on either. In contrast, bilateral microinjection of L741,626 into the PFC (but not striatum) caused a dose-related (0.63–2.5 μg/side) impairment of NOR. These observations suggest that blockade of dopamine D₃ receptors enhances both SND and NOR, whereas D₃ receptor activation or antagonism of dopamine D₂ receptor impairs cognition in these paradigms. Furthermore, these actions are mediated, at least partly, by the PFC. These data have important implications for exploitation of dopaminergic mechanisms in the treatment of schizophrenia and other CNS disorders, and support the potential therapeutic utility of dopamine D₃ receptor antagonism.     

Pressure ulcer incidence in Dutch and German nursing homes: design of a prospective multicenter cohort study

Background

Pressure ulcers are a common and serious health care problem in all health care settings. Results from annual national pressure ulcer prevalence surveys in the Netherlands and Germany reveal large differences in prevalence rates between both countries over the past ten years, especially in nursing homes. When examining differences in prevalence and incidence rates, it is important to take into account all factors associated with the development of pressure ulcers. Numerous studies have identified patient related factors, as well as nursing related interventions as risk factors for the development of pressure ulcers. Next to these more process oriented factors, also structural factors such as staffing levels and staff quality play a role in the development of pressure ulcers. This study has been designed to investigate the incidence of pressure ulcers in nursing homes in the Netherlands and Germany and to identify patient related factors, nursing related factors and structural factors associated with pressure ulcer development. The present article describes the protocol for this study.

Methods/design

A prospective multicenter study is designed in which a cohort of newly admitted nursing home residents in 10 Dutch and 11 German nursing homes will be followed for a period of 12 weeks. Data will be collected by research assistants using questionnaires on four different levels: resident, staff, ward, and nursing home.

Discussion

The results of the study will provide information on the incidence of pressure ulcers in Dutch and German nursing homes. Furthermore, information will be gathered on the influence of patient related factors, nursing related factors and structural factors on the incidence of pressure ulcers. The present article describes the study design and addresses the study's strengths and weaknesses.     

Impact of a decade-long anti-malaria crusade in a West African community

ObjectiveTo assess the rate of utilization of long lasting insecticide treated bed nets (LLINs) which is one of the cardinal components of the program, a decade-long antimalarial campaign under the roll back malaria (RBM) initiative.MethodsThe study was carried out between October and December 2009 and cross-sectional in nature involving adult women in Otukpo town and environs. Households were selected using systematic sampling methods where all the adult women in each household were interviewed. Relevant information such as age, marital status, occupation, utilization of LLINs and reasons for non-utilization were obtained. Data obtained were analysed using analysis of variance (ANOVA) and regression coefficient.ResultsAlmost 100% (3 154) of the respondents could associate malaria fever with mosquito bite although other causes were also mentioned. The overall any bed net utilization in Otukpo town was found to be 58.3% (1 849). LLINs utilization was found to be 23.3% (739). 35.0% (1 110) used untreated bed nets while 41.7% (1 322) had no bed net. Positive predictors for LLINs utilization were increasing educational levels, increasing wealth index and presence of an under five child, while lower wealth index and cultural beliefs negatively contributed to LLINs utilization.ConclusionsThe RBM program in the community has failed to yield the desired results. Efforts should be intensified towards addressing the socioeconomic, cultural, literary and logistic factors in order to reach this goal.     

Initiation of health-behaviour change among employees participating in a web-based health risk assessment with tailored feedback

Background

Biological monitoring of healthy workers exposed to hazardous dusts lack validated screening tools. Induced sputum (IS) cellular profile was compared with bronchoalveolar lavage fluid (BALF) profile in asbestos exposed workers in order to assess its usefulness in monitoring workers exposed to asbestos for a long period of time.

Methods

IS and BALF analysis was performed in 39 workers of a car brakes and clutches factory that uses chrysotile asbestos. Selection criteria were an employment history of > 15 years and the absence of a diagnosis of pneumonoconiosis. The type of cells, the existence of dust cells, of iron laden macrophages and of asbestos bodies were assessed and compared between IS and BALF samples.

Results

35 IS samples (90%) had dust cells, 34 (87%) iron laden macrophages and in 8 samples (21%) asbestos bodies were found. In most samples neutrophils were dominated. Samples with asbestos bodies (ABs) had significantly higher lymphocytes and lower neutrophils count compared with the samples without ABs. Macrophages and neutrophils in IS and BALF exhibited significant inter-relations (Spearman's rho: 0.26-0.29, p < 0.05) while IS lymphocytes count showed an inverse relation with BALF neutrophils (Spearman's rho: -0.36). Neutrophils and dust cells were highly correlated between the samples (Spearman's rho: 0.35, p < 0.05) while IS dust cells and lymphocytes were inversely related (Spearman's rho: -0.36, p < 0.05). More years of employment in the company was related with more neutrophils (Spearman's rho: 0.26) and less lymphocytes (Spearman's rho: -0.33) count. In multivariate analysis the presence of AB in IS samples was strongly related to the presence of asbestos bodies and lymphocytes count in BALF samples.

Conclusions

IS and BALF analysis showed a similar cellular profile indicating that IS sampling in exposed workers to asbestos as a less invasive and expensive method may be useful in providing an insight both for inhalation of dusts and inflammatory processes in the lung.     

Multiple liver abscesses with isolation of streptococcus intermedius related to a pyogenic dental infection in an immuno-competent patient

Introduction

Streptococcus intermedius - a member of the Streptococcus anginosus group - is part of the normal microbial flora of the oral cavity. Despite being regarded as a harmless apathogenic commensal, Streptococcus intermedius has been described to cause abscesses in various locations of the body.

Case Presentation

We report the clinical case and course of treatment of a 18-year-old male patient presenting with multiple hepatic abscesses associated with an untreated pyogenic dental infection.

Conclusion

Streptococcus intermedius can cause liver abscesses emerging from dental infectious foci even in previously healthy patients without underlying innate or aquired immunodeficiency. The case illustrates the potential danger and underestimated risk associated with untreated dental infections.     

Which mesh for hernia repair?

INTRODUCTION

The concept of using a mesh to repair hernias was introduced over 50 years ago. Mesh repair is now standard in most countries and widely accepted as superior to primary suture repair. As a result, there has been a rapid growth in the variety of meshes available and choosing the appropriate one can be difficult. This article outlines the general properties of meshes and factors to be considered when selecting one.

MATERIALS AND METHODS

We performed a search of the medical literature from 1950 to 1 May 2009, as indexed by Medline, using the PubMed search engine (<http://www.pubmed.gov>). To capture all potentially relevant articles with the highest degree of sensitivity, the search terms were intentionally broad. We used the following terms: ‘mesh, pore size, strength, recurrence, complications, lightweight, properties’. We also hand-searched the bibliographies of relevant articles and product literature to identify additional pertinent reports.

RESULTS AND CONCLUSIONS

The most important properties of meshes were found to be the type of filament, tensile strength and porosity. These determine the weight of the mesh and its biocompatibility. The tensile strength required is much less than originally presumed and light-weight meshes are thought to be superior due to their increased flexibility and reduction in discomfort. Large pores are also associated with a reduced risk of infection and shrinkage. For meshes placed in the peritoneal cavity, consideration should also be given to the risk of adhesion formation. A variety of composite meshes have been promoted to address this, but none appears superior to the others. Finally, biomaterials such as acellular dermis have a place for use in infected fields but have yet to prove their worth in routine hernia repair.