Genetic parameters of birth weight trait in dromedary camels (Camelus dromedarius).

Birth weight data of dromedary calves from the database of one of the world's largest dairy herds (Dubai, UAE) were analyzed for the period from 2007 to 2018. The assessment included the data of 4124 camel calves that were classified into six ecotypes (Emirate, Emirate crossed, Black, Pakistanian, Saudi-Sudanian, and Saudi crossed). The aim of the study was to describe the heritability of birth weight of calves and the breeding value of sires. Genetic parameters of birth weight were estimated by ANOVA model and two BLUP animal models as well. The mean value of the camel calves' birth weight was 34.75 ± 5.67 kg. The direct heritability of birth weight (h2d = 0.09 ± 0.04-0.11 ± 0.03) was rather low, so was the maternal heritability (h2m = 0.23 ± 0.10-0.50 ± 0.06). The maternal effect from environmental origin (c2 = 0.23 ± 0.08) far exceeded the results previously calculated in cattle. There was no difference in reliability between BLUP1 and BLUP2 models, and both of them were more accurate than the ANOVA model. Based on the results of this study, we conclude that the birth weight of dromedary calves was more influenced by the dam's intrauterine rearing capacity and by the environment, management, and feeding of the pregnant female camels than the hereditary growth potential. Considerable differences were found among male dromedaries in their breeding values for the birth weight trait.

Driving safety improves after individualized training: An RCT involving older drivers in an urban area.

Objective: This study aimed to reproduce the results of a previous investigation on the safety benefits of individualized training for older drivers. We modified our method to address validity and generalizability issues. Methods: Older drivers were randomly assigned to one of the 3 arms: (1) education alone, (2) education + on road training, and (3) education + on road + simulator training. Older drivers were recruited from a larger urban community. At the pre- and posttests (separated by 4 to 8 weeks) participants followed driving directions using a Global Positioning System (GPS) navigation system. Results: Our findings support the positive influence of individualized on-road training for urban-dwelling older drivers. Overall, driving safety improved among drivers who received on-road training over those who were only exposed to an education session, F(1, 40) = 11.66, P = .001 (26% reduction in total unsafe driving actions [UDAs]). Statistically significant improvements were observed on observation UDAs (e.g., scanning at intersections, etc.), compliance UDAs (e.g., incomplete stop), and procedural UDAs (e.g., position in lane). Conclusion: This study adds to the growing evidence base in support of individualized older driver training to optimize older drivers' safety and promote continued safe driving.

Effect of DGAT1 and TG gene polymorphisms on intramuscular fat and on milk production traits in different cattle breeds in Hungary.

The objective of this study was to estimate the effect of the thyroglobulin (TG) locus on beef quality traits in some beef cattle breeds and to investigate the effect of the DGAT1 locus on milk production traits in the Hungarian Holstein Friesian population. TG and DGAT1 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. At the TG locus TT bulls showed the highest fat percentage values in the longissimus dorsi muscle (m. longissimus dorsi); the difference between CC and TT genotypes was significant. DGAT1 GC/GC cows had the highest milk, fat and protein yield values. Due to the relatively small number of GC/GC cows the difference proved to be significant only between AA/AA and AA/GC genotypes.

The P-selectin, tissue factor, coagulation triad.

The primary importance of tissue factor (TF) in blood coagulation and thrombus propagation has been recognized for many years. Nevertheless, our view about the origin of TF activity, necessary for normal hemostasis and found in pathologic conditions, needs to be revised in the light of recent observations. Pioneering work by Yale Nemerson's group showed that circulating TF on microparticles (MPs), could promote thrombus growth. The origin and characteristics of this 'blood-borne' TF are targets of intense research as well as intense debate. Surprising observations now implicate the adhesion receptor P-selectin (P-sel), known for its role in inflammation, in these MPs' generation. P-sel, translocated from granules to the cell surfaces of activated platelets and endothelial cells, was recently found to play multiple roles in hemostasis. Expressed on endothelium, it can mediate platelet rolling. Signaling by P-sel through its receptor on leukocytes, P-selectin glycoprotein ligand 1 (PSGL-1), induces the generation of TF-positive, highly procoagulant MPs. In addition, P-sel on activated platelets helps to recruit these MPs specifically to thrombi. In this review, we discuss the roles of P-sel and TF-positive MPs and highlight strategies to modulate hemostasis by modulating the P-sel, TF, coagulation triad.

Meaning of occupational engagement in life-threatening illness: a qualitative pilot project.

INTRODUCTION: The onset of a personal crisis combined with the resultant disruption in occupational routines may challenge a person's identity as a capable and healthy individual. However, it remains unclear how individuals regain a sense of health and well-being in the period following a personal crisis. RESEARCH OBJECTIVE: To explore occupational engagement and its meaning to individuals following a life-threatening diagnosis. METHOD: Semi-structured interviews were conducted with three women diagnosed with breast cancer. The data were analyzed using a constant-comparative approach to identify common themes. RESULTS: The primary theme that emerged was "Doing = Living." This theme and the underlying themes illustrated the connection between meaningful occupational engagement and one's self-perception as capable and healthy. These findings suggest that occupational engagement may provide the medium through which 'deconstructive' or 'reconstructive' messages concerning the self are relayed between persons and their environment. IMPLICATIONS: In a period of personal crisis, such as a life-threatening diagnosis, individuals may turn to those occupations that are meaningful to regain a sense of control and normalcy in their lives.

Aggretin, a heterodimeric C-type lectin from Calloselasma rhodostoma (Malayan pit viper), stimulates platelets by binding to α2ß1 integrin and glycoprotein Ib, activating Syk and phospholipase Cγ 2, but does not involve the glycoprotein VI/Fc receptor γ chain collagen receptor.

Aggretin, a potent platelet activator, was isolated from Calloselasma rhodostoma venom, and 30-amino acid N-terminal sequences of both subunits were determined. Aggretin belongs to the heterodimeric snake C-type lectin family and is thought to activate platelets by binding to platelet glycoprotein alpha(2)beta(1). We now show that binding to glycoprotein (GP) Ib is also required. Aggretin-induced platelet activation was inhibited by a monoclonal antibody to GPIb as well as by antibodies to alpha(2)beta(1). Binding of both of these platelet receptors to aggretin was confirmed by affinity chromatography. No binding of other major platelet membrane glycoproteins, in particular GPVI, to aggretin was detected. Aggretin also activates platelets from Fc receptor gamma chain (Fcgamma)-deficient mice to a greater extent than those from normal control mice, showing that it does not use the GPVI/Fcgamma pathway. Platelets from Fcgamma-deficient mice expressed fibrinogen receptors normally in response to collagen, although they did not aggregate, indicating that these platelets may partly compensate via other receptors including alpha(2)beta(1) or GPIb for the lack of the Fcgamma pathway. Signaling by aggretin involves a dose-dependent lag phase followed by rapid tyrosine phosphorylation of a number of proteins. Among these are p72(SYK), p125(FAK), and PLCgamma2, whereas, in comparison with collagen and convulxin, the Fcgamma subunit neither is phosphorylated nor coprecipitates with p72(SYK). This supports an independent, GPIb- and integrin-based pathway for activation of p72(SYK) not involving the Fcgamma receptor.

Protein kinase C phosphorylation of syntaxin 4 in thrombin-activated human platelets.

We postulated that the syntaxins, because of their key role in SNARE complex formation and exocytosis, could be important targets for signaling by intracellular kinases involved in secretion. We found that syntaxin 4 was phosphorylated in human platelets treated with a physiologic agent that induces secretion (thrombin) but not when they were treated with an agent that prevents secretion (prostacyclin). Syntaxin 4 phosphorylation was blocked by inhibitors of activated protein kinase C (PKC), and, in parallel assays, PKC inhibitors also blocked secretion from thrombin-activated platelets. In platelets, cellular activation by thrombin or phorbol 12-myristate 13-acetate decreased the binding of syntaxin 4 with SNAP-23, another platelet t-SNARE. Phosphatase inhibitors increased syntaxin 4 phosphorylation and further decreased syntaxin 4-SNAP-23 binding induced by cell activation. Conversely, a PKC inhibitor blocked syntaxin 4 phosphorylation and returned binding of syntaxin 4-SNAP-23 to that seen in nonstimulated platelets. In vitro, PKC directly phosphorylated platelet syntaxin 4 and recombinant syntaxin 4. PKC phosphorylation in vitro inhibited (71 +/- 8%) the binding of syntaxin 4 to SNAP-23. These results provide evidence that extracellular activation can be coupled through intracellular PKC signaling so as to modulate SNARE protein interactions involved in platelet exocytosis.

Success in life for older adolescents with cerebral palsy.

In this article, the psychosocial themes emerging from an exploratory qualitative study are reported. Using a constant comparative method, the authors describe how older adolescents with cerebral palsy defined success in life and the factors they viewed as helping or hindering their success. Participants were 10 adolescents with cerebral palsy between 18 and 20 years of age who took part in a semistructured interview exploring their perceptions of success. For these adolescents, success meant being happy in life. Three key psychosocial factors were related to success in life: being believed in, believing in yourself, and being accepted by others (belonging). The findings are useful in guiding the design of services to meet the life needs of individuals with disabilities.

The platelet collagen receptor glycoprotein VI is a member of the immunoglobulin superfamily closely related to FcalphaR and the natural killer receptors.

We have cloned the platelet collagen receptor glycoprotein (GP) VI from a human bone marrow cDNA library using rapid amplification of cDNA ends with platelet mRNA to complete the 5' end sequence. GPVI was isolated from platelets using affinity chromatography on the snake C-type lectin, convulxin, as a critical step. Internal peptide sequences were obtained, and degenerate primers were designed to amplify a fragment of the GPVI cDNA, which was then used as a probe to screen the library. Purified GPVI, as well as Fab fragments of polyclonal antibodies made against the receptor, inhibited collagen-induced platelet aggregation. The GPVI receptor cDNA has an open reading frame of 1017 base pairs coding for a protein of 339 amino acids including a putative 23-amino acid signal sequence and a 19-amino acid transmembrane domain between residues 247 and 265. GPVI belongs to the immunoglobulin superfamily, and its sequence is closely related to FcalphaR and to the natural killer receptors. Its extracellular chain has two Ig-C2-like domains formed by disulfide bridges. An arginine residue is found in position 3 of the transmembrane portion, which should permit association with Fcgamma and its immunoreceptor tyrosine-based activation motif via a salt bridge. With 51 amino acids, the cytoplasmic tail is relatively long and shows little homology to the C-terminal part of the other family members. The ability of the cloned GPVI cDNA to code for a functional platelet collagen receptor was demonstrated in the megakaryocytic cell line Dami. Dami cells transfected with GPVI cDNA mobilized intracellular Ca(2+) in response to collagen, unlike the nontransfected or mock transfected Dami cells, which do not respond to collagen.

Enabling occupational performance: optimal experiences in therapy.

Occupational therapists believe that engagement in occupation contributes to health through an individually balanced use of time, a positive focus for one's physical and mental energy, and the provision of a sense of purpose. Flow is a construct which describes optimal experiences or enjoyment in everyday activities. A review of the literature suggests that the theory of optimal experience is complementary to occupational therapy beliefs and that an understanding of the flow experience may contribute to our understanding of human occupation. Specifically, flow may be useful in understanding those aspects of the occupation, environment and person that contribute to a "just right" challenge, and to enabling occupational performance through enjoyable, structured and purposeful activity. Occupational therapists are encouraged to explore whether optimal experiences facilitate occupational performance for individuals with a disability. Future research could explore whether the occupational opportunities available to persons with a disability provide the degree of challenge required to elicit the optimal experience. Finally, research could explore whether the client-driven selection of meaningful occupation, and therapist enablement of the "just right" challenge, influences optimal experience, occupational performance, and life satisfaction for those with a disability.

A critical role for N-ethylmaleimide-sensitive fusion protein (NSF) in platelet granule secretion.

The molecular mechanisms that regulate membrane targeting/fusion during platelet granule secretion are not yet understood. N-ethylmaleimide-sensitive fusion protein (NSF), soluble NSF attachment proteins (SNAPs), and SNAREs (SNAP receptors) are elements of a conserved molecular machinery for membrane targeting/fusion that have been detected in platelets. We examined whether NSF, an ATPase that has been shown to play a critical role in membrane targeting/fusion in many cell types, is necessary for platelet granule secretion. Peptides that mimic NSF sequence motifs inhibited both alpha-granule and dense-granule secretion in permeabilized human platelets. This inhibitory effect was sequence-specific, because neither proteinase K-digested peptides nor peptides containing similar amino acids in a scrambled sequence inhibited platelet secretion. The peptides that inhibited platelet granule secretion also inhibited the human recombinant alpha-SNAP-stimulated ATPase activity of recombinant NSF. It was also found that anti-NSF antibodies, which inhibited recombinant alpha-SNAP-stimulated ATPase activity of NSF, inhibited platelet granule secretion in permeabilized cells. The inhibition by anti-NSF antibodies was abolished by the addition of recombinant NSF. These data provide the first functional evidence that NSF plays an important role in platelet granule secretion.

Platelet glycoprotein Ia* is the processed form of multimerin--isolation and determination of N-terminal sequences of stored and released forms.

Glycoprotein Ia* (GPIa*), a very high molecular mass, platelet alpha-granule protein consisting of 167 kDa subunits disulphide-linked in a multimeric structure, was first described by Bienz and Clemetson in 1989 (J. Biol. Chem. 264, 507-514). In 1991 Hayward et al. (J. Biol. Chem. 266, 7114-7120) independently identified a platelet protein with multimeric structure. Despite strong similarities to GPIa* they concluded that it was a novel multimeric protein and named it first p-155 and later, multimerin. Multimerin has also been found in endothelial cells and has been cloned recently from an endothelial cell cDNA library. This has made it possible for us to clarify the relationship between GPIa* and multimerin. GPIa* was isolated from platelet releasate and the N-terminal sequence of 167 kDa and 155 kDa subunit species were determined. The N-terminal 15 amino acids of GPIa* were identical to the deduced amino acids 184-198 of endothelial multimerin. The N-terminal sequence of the 155 kDa protein was identical to the deduced amino acids 318-326 of multimerin. Thus, platelet GPIa* (167 kDa) is the main processed form of multimerin stored in platelet alpha-granules. The GPIa*/processed multimerin (167 kDa) still contains an RGDS sequence near its N-terminus as well as an EGF domain which may be involved in binding to the platelet surface after release. This sequence and domain are cleaved off in the p-155 form, described earlier as platelet multimerin, which is probably formed after release from alpha-granules.

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.

Snake venom C-type lectins as tools in platelet research.

The snake C-type lectins are a major group of proteins present in venoms that fold to a structure with similarities to classic C-type lectins. The loop that would be involved in calcium and sugar binding is truncated and heterodimers are linked by a disulphide bond and by swapping loop domains between the subunits. M any of these C-type lectins interact with platelet receptors to inhibit or induce platelet activation. The use of these C-type lectins to investigate platelet function is discussed and illustrated with specific examples.

Human group II 14 kDa phospholipase A2 activates human platelets.

Recombinant human group II phospholipase A2 (sPLA2) added to human platelets in the low microg/ml range induced platelet activation, as demonstrated by measurement of platelet aggregation, thromboxane A2 generation and influx of intracellular free Ca2+ concentration and by detection of time-dependent tyrosine phosphorylation of platelet proteins. The presence of Ca2+ at low millimolar concentrations is a prerequisite for the activation of platelets by sPLA2. Mg2+ cannot replace Ca2+. Mg2+, given in addition to the necessary Ca2+, inhibits sPLA2-induced platelet activation. Pre-exposure to sPLA2 completely blocked the aggregating effect of a second dose of sPLA2. Albumin or indomethacin inhibited sPLA2-induced aggregation, similarly to the inhibition of arachidonic acid-induced aggregation. Platelets pre-treated with heparitinase or phosphatidylinositol-specific phospholipase C lost their ability to aggregate in response to sPLA2, although they still responded to other agonists. This suggests that a glycophosphatidylinositol-anchored platelet-membrane heparan sulphate proteoglycan is the binding site for sPLA2 on platelets. Previous reports have stated that sPLA2 is unable to activate platelets. The inhibitory effect of albumin and Mg2+, frequently used in aggregation studies, and the fact that isolated platelets lose their responsiveness to sPLA2 relatively quickly, may explain why the platelet-activating effects of sPLA2 have not been reported earlier.

Platelet activation and signal transduction by convulxin, a C-type lectin from Crotalus durissus terrificus (tropical rattlesnake) venom via the p62/GPVI collagen receptor.

Convulxin, a powerful platelet activator, was isolated from Crotalus durissus terrificus venom, and 20 amino acid N-terminal sequences of both subunits were determined. These indicated that convulxin belongs to the heterodimeric C-type lectin family. Neither antibodies against GPIb nor echicetin had any effect on convulxin-induced platelet aggregation showing that, in contrast to other venom C-type lectins acting on platelets, GPIb is not involved in convulxin-induced platelet activation. In addition, partially reduced/denatured convulxin only affects collagen-induced platelet aggregation. The mechanism of convulxin-induced platelet activation was examined by platelet aggregation, detection of time-dependent tyrosine phosphorylation of platelet proteins, and binding studies with 125I-convulxin. Convulxin induces signal transduction in part like collagen, involving the time-dependent tyrosine phosphorylation of Fc receptor gamma chain, phospholipase Cgamma2, p72(SYK), c-Cbl, and p36-38. However, unlike collagen, pp125(FAK) and some other bands are not tyrosine-phosphorylated. Convulxin binds to a glycosylated 62-kDa membrane component in platelet lysate and to p62/GPVI immunoprecipitated by human anti-p62/GPVI antibodies. Convulxin subunits inhibit both aggregation and tyrosine phosphorylation in response to collagen. Piceatannol, a tyrosine kinase inhibitor with some specificity for p72(SYK), showed differential effects on collagen and convulxin-stimulated signaling. These results suggest that convulxin uses the p62/GPVI but not the alpha2beta1 part of the collagen signaling pathways to activate platelets. Occupation and clustering of p62/GPVI may activate Src family kinases phosphorylating Fc receptor gamma chain and, by a mechanism previously described in T- and B-cells, activate p72(SYK) that is critical for downstream activation of platelets.

Amino acid sequence of the alpha subunit and computer modelling of the alpha and beta subunits of echicetin from the venom of Echis carinatus (saw-scaled viper).

Echicetin, a heterodimeric protein from the venom of Echis carinatus, binds to platelet glycoprotein Ib (GPIb) and so inhibits platelet aggregation or agglutination induced by various platelet agonists acting via GPIb. The amino acid sequence of the beta subunit of echicetin has been reported and found to belong to the recently identified snake venom subclass of the C-type lectin protein family. Echicetin alpha and beta subunits were purified. N-terminal sequence analysis provided direct evidence that the protein purified was echicetin. The paper presents the complete amino acid sequence of the alpha subunit and computer models of the alpha and beta subunits. The sequence of alpha echicetin is highly similar to the alpha and beta chains of various heterodimeric and homodimeric C-type lectins. Neither of the fully reduced and alkylated alpha or beta subunits of echicetin inhibited the platelet agglutination induced by von Willebrand factor-ristocetin or alpha-thrombin. Earlier reports about the inhibitory activity of reduced and alkylated echicetin beta subunit might have been due to partial reduction of the protein.

Asp-49 is not an absolute prerequisite for the enzymic activity of low-M(r) phospholipases A2: purification, characterization and computer modelling of an enzymically active Ser-49 phospholipase A2, ecarpholin S, from the venom of Echis carinatus sochureki (saw-scaled viper).

Several studies have shown that Asp-49 is the residue that controls calcium binding in, and so plays a critical role in the calcium-mediated activation of, low-M(r) group I-III phospholipases A2 (PLA2s). The present paper provides experimental evidence that Asp-49 is not an absolute prerequisite for the enzymic activity of PLA2s, and that proteins with amino acid(s) other than Asp at position 49 can exhibit significant phospholipase activity. The purification, complete amino acid sequence and characterization of ecarpholin S, a PLA2 from Echis carinatus sochureki (saw-scaled viper) venom, is described. This single-chain, 122-amino-acid, basic (pI 7.9) protein is a group II PLA2. Although Asp-49 is replaced by Ser and Tyr-28 by Phe (both of these positions being involved in the Ca(2+)-binding site of PLA2s), the lipolysis of soybean phosphatidylcholine and egg yolk in the presence of 10 mM CaCl2 was 1.5 times and 2.9 times greater respectively with ecarpholin S than with recombinant human group II PLA2. The Ca(2+)-dependencies of the enzymic activities of ecarpholin S and rPLA2 were found to be similar. Ecarpholin S added to washed platelets induced aggregation; the presence of Ca2+ was a prerequisite for this platelet-aggregating effect. Computer modelling of the Ca(2+)-binding site of Ser-49 PLA2 compared with the Asp-49 and Lys-49 forms, for which crystallographic data exist, shows that the Ca(2+)-binding site is sterically blocked by Lys-49 but not by Ser-49; in the latter, the Ser hydroxy group may replace the Asp carboxylate in stabilization of Ca2+ binding. Sequence comparisons of ecarpholin S and other low-M(r) PLA2s predicts the presence of a Ser-49 group in the protein family of low-M(r) PLA2s that is distinct from the Asp-49 and Lys-49 groups.

Transformation of cellular factor XIII into an active zymogen transglutaminase in thrombin-stimulated platelets.

The cellular form of blood coagulation factor XIII (FXIII) is present in platelets, monocytes and macrophages. During long-term stimulation of platelets by thrombin cellular FXIII becomes activated and cross-links proteins, however, the mechanism of its activation has not been elucidated. It was shown that, contrary to plasma FXIII, the intracellular activation of platelet FXIII does not involve proteolysis. FXIII remained intact in thrombin-activated platelets, i.e., the activation peptide was not removed from the molecule. Part of the zymogen FXIII molecules, however, assumed an active configuration as was demonstrated both by the measurement of transglutaminase activity and by active-site-SH titration. These findings clearly indicate that during platelet activation, when intracellular Ca2+ concentration is raised, a slow non-proteolytic transformation of FXIII zymogen into an active transglutaminase occurs.