Adenosine diphosphate (ADP) and ADP receptor play a major role in platelet activation/aggregation induced by sera from heparin-induced thrombocytopenia patients

The molecular basis for heparin-induced thrombocytopenia (HIT), a relatively common complication of heparin therapy, is not yet fully understood. We found that pretreatment of platelets with AR-C66096 (formerly FPL 66096), a specific platelet adenosine diphosphate (ADP) receptor antagonist, at a concentration of 100 to 200 nmol/L that blocked ADP-dependent platelet aggregation, resulted in complete loss of platelet aggregation responses to HIT sera. AR-C66096 also totally inhibited HIT serum-induced dense granule release, as judged by measurement of adenosine triphosphate (ATP) release. Apyrase, added to platelets at a concentration that had only minor effects on thrombin- or arachidonic acid-induced aggregation, also blocked completely HIT serum-induced platelet aggregation. Furthermore, AR-C66096 inhibited platelet aggregation and ATP release induced by cross-linking Fc gamma RIIA with specific antibodies. These data show that released ADP and the platelet ADP receptor play a pivotal role in HIT serum-induced platelet activation/aggregation. The thromboxane receptor inhibitor, Daltroban, had no effect on HIT serum-induced platelet activation whereas GPIIb-IIIa antagonists blocked platelet aggregation but had only a moderate effect on HIT serum-induced dense granule release. Pretreatment of platelets with chondroitinases but not with heparinases resulted in concentration dependent inhibition of HIT serum-induced platelet aggregation. These novel data relating to the mechanism of platelet activation induced by HIT sera suggest that the possibility should be examined that ADP receptor antagonists or compounds that inhibit ADP release may be effective as therapeutic agents for the prevention or treatment of complications associated with heparin therapy.

The alpha and beta subunits of the metalloprotease meprin are expressed in separate layers of human epidermis, revealing different functions in keratinocyte proliferation and differentiation

The zinc endopeptidase meprin (EC 3.4.24.18) is expressed in brush border membranes of intestine and kidney tubules, intestinal leukocytes, and certain cancer cells, suggesting a role in epithelial differentiation and cell migration. Here we show by RT-PCR and immunoblotting that meprin is also expressed in human skin. As visualized by immunohistochemistry, the two meprin subunits are localized in separate cell layers of the human epidermis. Meprin alpha is expressed in the stratum basale, whereas meprin beta is found in cells of the stratum granulosum just beneath the stratum corneum. In hyperproliferative epidermis such as in psoriasis vulgaris, meprin alpha showed a marked shift of expression from the basal to the uppermost layers of the epidermis. The expression patterns suggest distinct functions for the two subunits in skin. This assumption is supported by diverse effects of recombinant meprin alpha and beta on human adult low-calcium high-temperature keratinocytes. Here, beta induced a dramatic change in cell morphology and reduced the cell number, indicating a function in terminal differentiation, whereas meprin alpha did not affect cell viability, and may play a role in basal keratinocyte proliferation.

TRPC1 is regulated by caveolin-1 and is involved in oxidized LDL-induced apoptosis of vascular smooth muscle cells

Oxidized low-density lipoprotein (oxLDL) induced-apoptosis of vascular cells may participate in plaque instability and rupture. We have previously shown that vascular smooth muscle cells (VSMC) stably expressing caveolin-1 were more susceptible to oxLDL-induced apoptosis than VSMC expressing lower level of caveolin-1, and this was correlated with enhanced Ca(2+) entry and pro-apoptotic events. In this study we aimed to identify the molecular events involved in oxLDL-induced Ca(2+) influx and their regulation by the structural protein caveolin-1. In VSMC, transient receptor potential canonical-1 (TRPC1) silencing by ARN interference, prevents the Ca(2+) influx and reduces the toxicity induced by oxLDL. Moreover, caveolin-1 silencing induces concomitant decrease of TRPC1 expression and reduces oxLDL-induced-apoptosis of VSMC. OxLDL enhanced the cell surface expression of TRPC1, as shown by biotinylation of cell surface proteins, and induced TRPC1 translocation into caveolar compartment, as assessed by subcellular fractionation. OxLDL-induced TRPC1 translocation was dependent on actin cytoskeleton and associated with a dramatic rise of 7-ketocholesterol (a major oxysterol in oxLDL) into caveolar membranes, whereas the caveolar content of cholesterol was unchanged. Altogether, the reported results show that TRPC1 channels play a role in Ca(2+) influx and Ca(2+) homeostasis deregulation that mediate apoptosis induced by oxLDL. These data also shed new light on the role of caveolin-1 and caveolar compartment as important regulators of TRPC1 trafficking to the plasma membrane and apoptotic processes that play a major role in atherosclerosis.

Pregnancy in patients with ankylosing spondylitis: do regulatory T cells play a role?

OBJECTIVE: To investigate the numerical and functional changes of CD4+CD25(high) regulatory T (Treg) cells during pregnancy and postpartum in patients with ankylosing spondylitis (AS). METHODS: The frequency of CD4+CD25(high) T cells was determined by flow cytometry in 10 pregnant and 5 nonpregnant patients with AS as well as in 14 pregnant and 4 nonpregnant healthy controls. Pregnant individuals were investigated at the third trimester and 8 weeks postpartum. Treg cells and CD4+CD25- effector T (Teff) cells separated by fluorescence-activated cell sorting were stimulated with anti-CD3 and anti-CD28 monoclonal antibodies, alone or in coculture, to investigate proliferation and cytokine secretion. RESULTS: The frequency of CD4+CD25(high) Treg cells was significantly higher during pregnancy than postpartum in both healthy control subjects and patients with AS. In contrast to Treg cells in healthy pregnant women, Treg cells in pregnant women with AS secreted only small amounts of interleukin-10 and showed lower suppression of tumor necrosis factor alpha and interferon-gamma secretion by CD4+CD25- Teff cells. At the postpartum time point, proinflammatory cytokine levels in the Treg/Teff cell cocultures and Teff cell monocultures were significantly higher in patients with AS than in healthy controls. CONCLUSION: Pregnancy influenced the expansion and cytokine secretion of Treg cells in both patients with AS and control subjects. However, the Treg cells of pregnant patients with AS failed to support an antiinflammatory cytokine milieu, thereby possibly contributing to the persistent disease activity of AS during pregnancy.

Establishment and expansion of Lake Malawi rock fish populations after a dramatic Late Pleistocene lake level rise

Major environmental events that fragment populations among multiple island habitats have potential to drive large-scale episodes of speciation and adaptive radiation. A recent palaeolimnological study of sediment cores indicated that Lake Malawi underwent major climate-driven desiccation events 75 000-135 000 years ago that lowered the water level to at least 580 m below the present state and severely reduced surface area. After this period, lake levels rose and stabilized, creating multiple discontinuous littoral rocky habitats. Here, we present evidence supporting the hypothesis that establishment and expansion of isolated philopatric rock cichlid populations occurred after this rise and stabilization of lake level. We studied the Pseudotropheus (Maylandia) species complex, a group with both allopatric and sympatric populations that differ in male nuptial colour traits and tend to mate assortatively. Using coalescent analyses based on mitochondrial DNA, we found evidence that populations throughout the lake started to expand and accumulate genetic diversity after the lake level rise. Moreover, most haplotypes were geographically restricted, and the greatest genetic similarities were typically among sympatric or neighbouring populations. This is indicative of limited dispersal and establishment of assortative mating among populations following the lake level rise. Together, this evidence is compatible with a single large-scale environmental event being central to evolution of spatial patterns of genetic and species diversity in P. (Maylandia) and perhaps other Lake Malawi rock cichlids. Equivalent climate-driven pulses of habitat formation and fragmentation may similarly have contributed to observed rapid and punctuated cladogenesis in other adaptive radiations.

Functional hoarseness in children: short-term play therapy with family dynamic counseling as therapy of choice

Children with nonorganic voice disorders (NVDs) are treated mainly using direct voice therapy techniques such as the accent method or glottal attack changes and indirect methods such as vocal hygiene and voice education. However, both approaches tackle only the symptoms and not etiological factors in the family dynamics and therefore often enjoy little success. The aim of the "Bernese Brief Dynamic Intervention" (BBDI) for children with NVD was to extend the effectiveness of pediatric voice therapies with a psychosomatic concept combining short-term play therapy with the child and family dynamic counseling of the parents. This study compares the therapeutic changes in three groups where different procedures were used, before intervention and 1 year afterward: counseling of parents (one to two consultations; n = 24), Brief Dynamic Intervention on the lines of the BBDI (three to five play therapy sessions with the child plus two to four sessions with the parents; n = 20), and traditional voice therapy (n = 22). A Voice Questionnaire for Parents developed by us with 59 questions to be answered on a four-point Likert scale was used to measure the change. According to the parents' assessment, a significant improvement in voice quality was achieved in all three methods. Counseling of parents (A) appears to have led parents to give their child more latitude, for example, they stopped nagging the child or demanding that he/she should behave strictly by the rules. After BBDI (B), the mothers were more responsive to their children's wishes and the children were more relaxed and their speech became livelier. At home, they called out to them less often at a distance, which probably improved parent-child dialog. Traditional voice therapy (C) seems to have had a positive effect on the children's social competence. BBDI seems to have the deepest, widest, and therefore probably the most enduring therapeutic effect on children with NVD.

Developing Dramatic Movies to Teach Interdisciplinary Collaboration to Allied Health, Medical and Nursing Students

Many times a Hollywood movie has scenes that are useful to illustrate aspects of health care practice. However, it is often impractical to use an entire two-hour movie in class, and a clip or two really does not convey the dramatic picture that the complete movie reveals. [See PDF for complete abstract]

The type-A horizontal cell: GABAergic characteristics and role in development of the outer plexiform layer

Morphological analysis of neonatal rabbit retina suggests that the type-A horizontal cell acts as the pioneer cell for development of the OPL. It is the first mature element of the OPL, and it forms the infrastructure upon which the OPL accrues. The role of type-A horizontal cells in influencing postnatal development of the OPL was examined.^ GABAergic characteristics of the type-A horizontal cell were defined. The type-A horizontal cell was found to possess two more GABAergic characteristics in addition to those previously demonstrated, during a short period in early postnatal development: endogenous stores of GABA and the GABA precursor, glutamate. Lesioning the type-A horizontal cell resulted in their permanent loss in addition to the disappearance of cone terminals and a dramatic increase in rod terminals within the OPL. Thus the type-A cells are not a necessary prerequisite for positioning the OPL in postnatal development, but may be necessary for establishment of the normal photoreceptor mosaic.^ Since type-A horizontal cells possess a number of GABAergic qualities during the period of cone photoreceptor cell differentiation, and there are reports of GABA's trophic action in other developing neuronal systems; the role that GABAergic type-A horizontal cells play in directing photoreceptor differentiation was examined.^ Disrupting effects of GABA-A receptor antagonists indicate that type-A horizontal cells act as postsynaptic targets for the growing cone terminals of photoreceptor cells. These trophic or synaptic interactions may involve GABA-A receptors activated by GABA released from horizontal cells. These findings are consistent with the hypothesis that type-A horizontal cells act as pioneering cells in directing the postnatal development of the OPL.^ These studies offer an in depth analysis of the structural and chemical relationship between type-A horizontal cells and other elements of the OPL from which the roles of type-A horizontal cells and the GABA system in development can be defined. They contribute to our knowledge of both structural and GABAergic mechanisms involved in central nervous system development. ^

Biomass and Stored Carbohydrate Compensation after Above-Ground Biomass Removal in a Perennial Herb: Does Environmental Productivity Play a Role?

Many plant species are able to tolerate severe disturbance leading to removal of a substantial portion of the body by resprouting from intact or fragmented organs. Resprouting enables plants to compensate for biomass loss and complete their life cycles. The degree of disturbance tolerance, and hence the ecological advantage of damage tolerance (in contrast to alternative strategies), has been reported to be affected by environmental productivity. In our study, we examined the influence of soil nutrients (as an indicator of environmental productivity) on biomass and stored carbohydrate compensation after removal of aboveground parts in the perennial resprouter Plantago lanceolata. Specifically, we tested and compared the effects of nutrient availability on biomass and carbon storage in damaged and undamaged individuals. Damaged plants of P. lanceolata compensated neither in terms of biomass nor overall carbon storage. However, whereas in the nutrient-poor environment, root total non-structural carbohydrate concentrations (TNC) were similar for damaged and undamaged plants, in the nutrient-rich environment, damaged plants had remarkably higher TNC than undamaged plants. Based on TNC allocation patterns, we conclude that tolerance to disturbance is promoted in more productive environments, where higher photosynthetic efficiency allows for successful replenishment of carbohydrates. Although plants under nutrient-rich conditions did not compensate in terms of biomass or seed production, they entered winter with higher content of carbohydrates, which might result in better performance in the next growing season. This otherwise overlooked compensation mechanism might be responsible for inconsistent results reported from other studies.