Relative torque contribution of vastus medialis muscle at different knee angles

Aim: We investigated the relative contribution of the vastus medialis (VM) muscle to total isometric knee extension torque at 10°, 30°, 60° and 90° knee flexion. In the past a more prominent role of the VM muscle at more extended knee angles has been put forward. However, different components of the quadriceps muscle converge via a common distal tendon. We therefore hypothesized that the relative contribution of the VM to total knee extension torque would be similar across angles. Methods: At each knee angle the EMG isometric torque relations [20%, 25%, 30%, 35% maximal voluntary contraction (MVC)] of the rectus femoris (RF), vastus lateralis (VL) and VM muscle were established in 10 healthy male subjects; rectified surface EMG was normalized to M‐wave area. Subsequently, the VM was functionally eliminated by selective electrical surface stimulation with occluded blood flow. Results: There was no evidence for preferential activation of VM at any of the knee angles. Following VM elimination, total knee extension torque during maximal femoral nerve stimulation (three pulses at 300Hz) at 10°, 30°, 60° and 90°, respectively, decreased (P < 0.05) to (mean ± SD): 75.7 ± 12.2, 75.1 ± 9.3, 78.2 ± 7.2 and 76.0 ± 5.8% (P > 0.05 among knee angles). In addition, during voluntary contractions at 20% MVC the increases in torque output of RF and VL compensating for the loss of VM function were calculated from the increases in EMG and found to be similar (P > 0.05) at 10°, 30°, 60° and 90° values (%MVC), respectively, were: 9.1 ± 6.8, 7.5 ± 2.9, 5.9 ± 3.7 and 6.9 ± 3.4. Conclusion: The present findings support our hypothesis that the VM contributes similarly to total knee extension torque at different knee angles.     

The Influence of Two Different Invitation Letters on Chlamydia Testing Participation: Randomized Controlled Trial

Background

In the Netherlands, screening for chlamydia (the most prevalent sexually transmitted infection worldwide) is a relatively simple and free procedure. Via an invitation letter sent by the public health services (PHS), people are asked to visit a website to request a test kit. They can then do a chlamydia test at home, send it anonymously to a laboratory, and, within two weeks, they can review their test results online and be treated by their general practitioner or the PHS. Unfortunately, the participation rates are low and the process is believed to be not (cost-) effective.

Objective

The objective of this study was to assess whether the low participation rate of screening for chlamydia at home, via an invitation letter asking to visit a website and request a test kit, could be improved by optimizing the invitation letter through systematically applied behavior change theories and evidence.

Methods

The original letter and a revised letter were randomly sent out to 13,551 citizens, 16 to 29 years old, in a Dutch municipality. Using behavior change theories, the revised letter sought to increase motivation to conduct chlamydia screening tests. The revised letter was tailored to beliefs that were found in earlier studies: risk perception, advantages and disadvantages (attitude), moral norm, social influence, and response- and self-efficacy. Revisions to the new letter also sought to avoid possible unwanted resistance caused when people feel pressured, and included prompts to trigger the desired behavior.

Results

No significant differences in test package requests were found between the two letters. There were also no differences between the original and revised letters in the rates of returned tests (11.80%, 581/4922 vs 11.07%, 549/4961) or positive test results (4.8%, 23/484 vs 4.1%, 19/460). It is evident that the new letter did not improve participation compared to the original letter.

Conclusions

It is clear that the approach of inviting the target population through a letter does not lead to higher participation rates for chlamydia screening. Other approaches have to be developed and pilot tested.     

No justification of routine screening for 22q11 deletions in patients with overt cleft palate

The velo-cardio-facial syndrome (VCFS), caused by a submicroscopic deletion of chromosome 22q11, is the most common syndrome that has palatal anomalies as a major feature. A possible strategy for early detection of VCFS is routine screening for 22q11 deletions in all infants with cleft palate (CP). The purpose of this study was to evaluate whether this strategy is preferable to testing on clinical suspicion. At the Nijmegen Cleft Palate Craniofacial Center, 58 new patients with overt CP were routinely tested, using fluorescence in situ hybridization (FISH), for a 22q11 deletion. One deletion was identified in a newborn girl with an overt CP who was clinically not suspected of having VCFS. Based on this study (n = 45) and the literature (n = 54), the prevalence of 22q11 deletions among children with CP, but without any other symptoms of VCFS, is estimated to be one in 99. We take the view that this figure is rather low and that early discovery will rarely have significant clinical or genetic consequences. Because CP patients remain under medical attention, almost all of the infants with isolated CP and VCFS will be recognized as having the syndrome at a later age when additional features have developed. Therefore, we conclude that routine FISH testing for 22q11 deletions in infants with overt CP is not indicated, provided clinical follow-up is guaranteed.     

AD/HD and the capture of attention by briefly exposed delay-related cues: evidence from a conditioning paradigm

BACKGROUND: The selective attention of children with attention deficit/hyperactivity disorder (AD/HD) to briefly exposed delay-related cues was examined in two experiments using a dot-probe conditioning paradigm. METHOD: Colour cues were paired with negatively (i.e., imposition of delay) and positively valenced cues (i.e., escape from or avoidance of delay) during a conditioning phase. These cues were presented alongside neutral cues in a subsequent dot-probe detection phase. RESULTS: In experiment 1 teacher-identified children with AD/HD (N = 12), but not controls (N = 12), displayed an attentional bias towards both positively and negatively valenced cues. In experiment 2 children with a diagnosis of hyperkinetic disorder (N = 15), but not controls (N = 15), displayed a bias towards delay-related cues. However, this effect was largely carried by the response to positively valenced cues. CONCLUSIONS: These results confirm the dot-probe conditioning paradigm as a useful test of motivational influence on attention. They provide the first evidence of qualitative differences in the attentional style of children with AD/HD and give further support to those theories that highlight the motivational significance of delay in AD/HD.     

Differential expression of leukocyte-associated Ig-like receptor-1 during neutrophil differentiation and activation

Inhibitory receptors containing immunoreceptor tyrosine-based inhibitory motifs play an important regulatory role in immune cell activation. In addition, several studies suggest that these receptors are involved in the regulation of hematopoietic cell differentiation. Here, we have investigated the expression of leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1), an inhibitory receptor expressed on most peripheral blood leukocytes and on CD34+ hematopoietic progenitor cells, in neutrophil differentiation and activation. We found that although LAIR-1 was expressed on peripheral blood eosinophils, cell-surface expression on mature neutrophils was low, suggesting that LAIR-1 expression is regulated during granulocyte differentiation. Indeed, the promyeloid cell line HL-60 expressed LAIR-1, but the expression decreased during chemical-induced differentiation toward neutrophils. Similarly, in bone marrow-derived neutrophil precursors, the most immature cells expressed LAIR-1, and loss of LAIR-1 expression was associated with neutrophil maturation. LAIR-1 was re-expressed rapidly on the membrane of mature neutrophils upon stimulation with tumor necrosis factor alpha, granulocyte macrophage-colony stimulating factor, or N-formyl-methionyl-leucyl-phenylalanine, indicating that LAIR-1 may also regulate neutrophil effector function. Our studies suggest that LAIR-1 may play a regulatory role in differentiation and function of human granulocytes.     

Host genetics of Bordetella pertussis infection in mice: significance of Toll-like receptor 4 in genetic susceptibility and pathobiology

The susceptibility to and the severity of Bordetella pertussis infections in infants and children varies widely, suggesting that genetic differences between individuals influence the course of infection. We have previously identified three novel loci that influence the severity of whooping cough by using recombinant congenic strains of mice: Bordetella pertussis susceptibility loci 1, 2, and 3 (Bps1, -2, and -3). Because these loci could not account for all genetic differences between mice, we extended our search for additional susceptibility loci. We therefore screened 11 inbred strains of mice for susceptibility to a pertussis infection after intranasal infection. Susceptibility was defined by the number of bacteria in the lungs, being indicative of the effect between the clearance and replication of bacteria. The most resistant (A/J) and the most susceptible (C3H/HeJ) strains were selected for further genetic and phenotypic characterization. The link between bacterial clearance and chromosomal location was investigated with 300 F2 mice, generated by crossing A/J and C3H/HeJ mice. We found a link between the delayed clearance of bacteria from the lung and a large part of chromosome 4 in F2 mice with a maximum log of the odds score of 33.6 at 65.4 Mb, which is the location of Tlr4. C3H/HeJ mice carry a functional mutation in the intracellular domain of Tlr4. This locus accounted for all detectable genetic differences between these strains. Compared to A/J mice, C3H/HeJ mice showed a delayed clearance of bacteria from the lung, a higher relative lung weight, and increased body weight loss. Splenocytes from infected C3H/HeJ mice produced almost no interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) upon ex vivo restimulation with B. pertussis compared to A/J mice and also showed a delayed gamma interferon (IFN-gamma) production. TNF-alpha expression in the lungs 3 days after infection was increased fivefold compared to uninfected controls in A/J mice and was not affected in C3H/HeJ mice. In conclusion, Tlr4 is a major host factor explaining the differences in the course of infection between these inbred strains of mice. Functional Tlr4 is essential for an efficient IL-1-beta, TNF-alpha, and IFN-gamma response; efficient clearance of bacteria from the lung; and reduced lung pathology.     

The role of VEGF-C staining in predicting regional metastasis in melanoma

Sentinel lymph node status is the most important prognostic factor in primary melanoma. The number of melanoma-associated lymphatic vessels has been associated with sentinel lymph node status and survival. Vascular endothelial growth factor-C (VEGF-C) is found to promote tumour-associated lymphatic vessel growth. In many human neoplasms, VEGF-C expression in neoplastic cells or tumour-associated macrophages (TAMs) has been linked to lymphatic dissemination of tumour cells. Recent studies have suggested a correlation between VEGF-C expression in primary melanoma and the presence of lymph node metastasis. We performed VEGF-C immunohistochemical staining on melanoma tissues of 113 patients with known sentinel lymph node status. We showed that both high VEGF-C expression in melanoma cells and TAMs are positively associated with the presence of a positive sentinel lymph node. No correlation with Breslow thickness, Clark invasion level or ulceration could be detected. VEGF-C expression in melanoma cells was predictive of a shorter overall and disease-free survival, without being an independent predictor of survival. Our results confirm that VEGF-C expression in primary cutaneous melanoma plays a role in the lymphatic spread of the tumour.