Validation study of a distress screener.

OBJECTIVES: A 3-item screening instrument called the Distress Screener was developed for early identification of distress among employees on sick leave. The Distress Screener consists of three items obtained from the distress subscale of the four-dimensional symptom questionnaire (4DSQ). This study assessed an optimal cut-off point and validated the Distress Screener by relating it to the 4DSQ and to medical diagnoses. METHODS: 171 sick-listed employees filled in the Distress Screener and the 4DSQ (containing four subscales: distress, depression, anxiety and somatisation) and medical diagnoses were obtained from occupational physicians (OPs). The optimal cut-off point was assessed by computing sensitivity and specificity values. Validity was assessed by relating the Distress Screener score to the scores on 4DSQ subscales. In addition scores were compared to mental health medical diagnoses and the degree of similarity between two repeated measurements was obtained. RESULTS: Using the 4DSQ distress score >10 as reference standard, the optimal cut-off point of the Distress Screener was > or =4. Regarding validity, a high correlation (0.82) existed between the Distress Screener and the 4DSQ distress subscale and it was significantly different from the correlations with the other 4DSQ subscales. Also a high correlation existed for the test-retest reliability (0.83). Furthermore, a high score on the Distress Screener seemed to be related to the medical diagnosis 'Stress-related complaints'. All low scores seemed to be related to the medical diagnosis 'Other complaints'. Sensitivity (0.85) and specificity (0.78) values, and positive and negative predictive values of the screener were comparable to those of the 4DSQ distress subscale. CONCLUSIONS: The Distress Screener is a valid instrument for use by the OP during consulting time as a quick scan for early identification of distress in employees on sick leave. The cut-off point > or =4 is useful for early identification of distress in employees on sick leave.

Frictional forces required for unrestrained locomotion in dairy cattle.

Most free-stall housing systems in the Netherlands are equipped with slatted or solid concrete floors with manure scrapers. A slipping incident occurs when the required coefficient of friction (RCOF) exceeds the coefficient of friction (COF) at the claw-floor interface. An experiment was conducted to measure ground reaction forces (GRF) of dairy cows (n = 9) performing various locomotory behaviors on a nonslippery rubber-covered concrete floor. The RCOF was determined as the ratio of the horizontal and vertical components of the GRF. It was shown that during straight walking and walking-a-curve, the RCOF reached values up to the COF, whereas for sudden stop-and-start responses, the RCOF reached values beyond the maximum COF that concrete floors can provide. Our results indicate that concrete floors do not provide enough friction to allow natural locomotory behavior and suggest that tractional properties of floors should be main design criteria in the development of better flooring surfaces for cattle.

The effect of preventive trimming on weight bearing and force balance on the claws of dairy cattle.

Claw disorders and lameness in dairy cattle are an increasing problem of the modern dairy industry. To prevent claw disorders from evolving from the subclinical to the clinical stage, trimming is the management practice most routinely applied. The goal of preventive trimming (Toussaint-Raven method) is to promote natural loading by increasing the weight-bearing contact area of the claws and improving the balance between the medial and lateral claw. The biomechanical effect of preventive claw trimming was investigated with the aid of pressure distribution and ground reaction force recordings of the standing cow sampled simultaneously at 250 Hz. It appeared that preventive trimming of the hind limbs (n = 10) brought the claws slightly more in balance. Before trimming, 80% of the total force is taken up by the lateral claw and 20% by the medial claw. After trimming, this becomes 70 to 30%, respectively. Thereby, a significant increase in the weight-bearing contact area from 27.5 to 40.0 cm2 was achieved, resulting in a significant decrease in average pressure. However, the claws remained subjected to unaltered, high maximum pressures after trimming. The suggestion was made that the main focus of claw trimming should not be force balance; instead, a reduction of local maximum pressures at the contact area should be targeted in such a way that the strongest parts of the claw capsule (i.e., the wall) will be subjected to the highest pressures.

The vertical ground reaction force and the pressure distribution on the claws of dairy cows while walking on a flat substrate.

The pressure distribution under the bovine claw while walking was measured to test the hypotheses that the vertical ground reaction force is unevenly distributed and makes some (regions of the) claws more prone to injuries due to overloading than others. Each limb of nine recently trimmed Holstein Friesian cows was measured five times while walking over a Footscan pressure plate firmly embedded on a Kistler force plate. The pressure plate had a spatial resolution of 2.6 sensors/cm2 and was sampled simultaneously with the force plate with a temporal resolution of 250 measurements/s. Five moments during the stance phase were selected on basis of the force plate recording for the analysis of the pressure distribution: heel strike, maximum braking, midstance, maximum propulsion, and push off. At the forelimbs, the vertical ground reaction force was equally distributed between medial and lateral claw. At the hind limbs at heel strike, the force was exerted almost completely to the lateral claw. During the rest of the stance phase the load shifted towards the medial claw, until, at push off, it was more or less equally divided between both claws. The average pressures determined were 50 to 80 N/cm2. Maximum pressures increased from 90 to 110 N/cm2 at heel strike to 180 to 200 N/cm2 at push off. It was concluded that at the hind limb these pressures constitute a major threat to overloading particularly for the softer parts of the lateral claw, e.g., the sole and bulb area.

The pressure distribution under the bovine claw during square standing on a flat substrate.

The distribution pattern of pressure over the bovine claw was investigated to test the hypothesis that the ground reaction force is unevenly distributed and makes some regions of the claw more prone to overloading and injury than others. In eight recently trimmed Holstein Friesian cows, the distribution of vertical pressure was measured during square standing with a spatial resolution of 2.6 sensors/cm2 and a temporal resolution of 313 measurements/s. In each animal, the localization of maximum pressure per foot and per claw was determined during five trials. In the front limb, maximum pressures were normally found on the medial claw; in the hindlimb they were located on the lateral claw. In both claws, the highest pressures were found on the sole of the foot and not on the wall. In the front limbs, maximum pressures were located in the posterior portion of the sole; in the hind limb in the anterior portion. There was no difference in the location of the maximum pressure between the medial and lateral claw in either limb. The regions in which these maximum pressures occur are known to be relatively susceptible to injuries. This could indicate a causal relation between the location of pressure concentrations and claw diseases found in clinical observations.

Cow behaviour on a new grooved floor in comparison with a slatted floor, taking claw health and floor properties into account.

The objective of this study was to compare the behaviour of cows on a grooved floor with that of cows kept on a slatted floor. The trial was carried out with two groups of 12 Holstein-Friesian cows kept in a cowshed with two symmetrical halves, identical except for the floor. One floor was grooved longitudinally to the feeding fence (width of grooves 35mm) and the other was slatted (gaps 35mm wide) perpendicular to the feeding fence. Both floors had scrapers to remove manure. After 3 weeks of being kept on these two floors, cows were switched between floors for 3 weeks. In the third week of each 3-week-period, behavioural observations of cows related to their time budget over 24h, relocation on each floor indicated by index of movement and specific behaviours (aggression, self maintenance) performed on the floors were executed. The health of claws was examined before the trial and 6 weeks later, after the trial. The grooved floor influenced the cows' daily time budget: cows kept on the grooved floor stood less (P<0.05) with four legs inside the cubicles (group 1: 36min, group 2: 39min) than cows kept on the slatted floor (group 1: 57min, group 2: 60min). Neither the specific behaviours of cows nor their movement performed on both floors were different. After switching from the grooved floor to the slatted floor, cows lay for 669min a day (in comparison to 746min a day while kept on the grooved floor, P<0.05) and they stood parallel to the feeding fence for 174min a day (in comparison to 126min a day while kept on the grooved floor, P<0.05). Given that both groups of cows on the grooved floor and the group that began on the slatted floor had a similar daily time budget, it is possible that the different time budget of the remaining group, which started off on the grooved floor, was a reaction (pleasure or disappointment) induced by returning to the familiar floor. The grooved floor was more fouled with faeces (P<0.05) than the slatted floor. The grooved floor can be evaluated as being equal to the slatted floor with a scraper in terms of the behaviour performed on it. There were hardly any slip incidents on it (during 64h of observations, two slip incidents on the grooved floor, four slip incidents on the slatted floor). However, the occurrence of stumble incidents involving the manure scraper (66 cases on the grooved floor and 48 on the slatted floor during 64h of observations) and the occurrence of foot lesions (probably of traumatic origin) suggests that the functioning of the manure scraper, which is indispensable on grooved floors, needs to be optimised.

Deficient IgA1 immune response to nasal cholera toxin subunit B in primary IgA nephropathy.

Twelve IgA nephropathy (IgAN) patients and 18 controls were immunized with novel protein antigens, cholera toxin subunit B (CTB) via the nasal route and keyhole limpet hemocyanin (KLH) subcutaneously. Antibody secreting cells and antibody response in body fluids were determined by ELISPOT assay and ELISA, respectively. Analysis of variance showed, in contrast to controls (P < 0.001), no CTB-specific IgA response in the nasal washes of patients with IgAN. Significantly lower numbers of CTB-specific antibody-secreting cells in peripheral blood (P < 0.001) and CTB-specific antibodies in plasma (P < 0.005) were found in IgAN, both restricted to the IgA1 subclass. The proportions of CTB-specific IgA1-secreting cells in bone marrow aspirates correlated significantly with the corresponding ratios in plasma, with significantly lower values (P < 0.005) in IgAN as compared to controls. These results support the existence of a "mucosa-bone marrow axis" in humans, but no dysregulation of this axis was found in IgAN. The deficient mucosal IgA immune response to CTB observed in this study after primary mucosal immunization indicates that patients with IgAN have a defective immune response when challenged intranasally. These patients may depend on more frequent and/or prolonged antigen encounter at mucosal sites before efficient mucosal immunity is established. Repeated seeding of antigen-specific cells to secondary lympoid organs could result secondarily in the relative hyperresponsiveness found in IgAN upon reactivation by parenteral immunization.

Immunoglobulin A subclass measurement in serum and saliva: sensitivity of detection of dimeric IgA2 in ELISA depends on the antibody used.

The existence of two IgA subclasses in humans has been reliably shown by biochemical, immunochemical and genetic means. IgA is unique among immunoglobulins in the regular occurrence of both monomeric and polymeric forms. In order to be able to study the relationship between monomeric and polymeric IgA1 and IgA2 concentrations in the circulation and mucosal compartment i.e. secretions, it is essential that the methods used are not biased by the molecular size of the IgA under investigation. We validated IgA and IgA subclass measurements in serum and saliva by sandwich enzyme-linked immunosorbent assay (ELISA). Coating reagents were specific mAbs against IgA (clone 4E8), IgA1 (clone 69-11.4) or IgA2 (clone 16-512-H5 and clone IF8.58). Pooled normal human serum and purified dimeric IgA1 (d-IgA1) or IgA2 (d-IgA2) myeloma proteins were used to standardize the assays. Polymeric and monomeric forms of IgA in sera from volunteers and patients with myelomatosis were assayed in fractions separated by high performance liquid chromatography (HPLC). Dithioerythritol (DTE) was used to determine the influence of the quarternary structure of IgA on its detection by mAbs. We found that mAbs 4E8, 69-11.4 and 16-512-H5 reliably measured d-IgA, d-IgA1 and d-IgA2 respectively, independent of the standard employed. Clone IF8.58 underestimated the concentration of d-IgA2 (correction factor +/- 2) with increased sensitivity in the presence of DTE. This difference is probably explained by the composition of the immunogen against which the mAb was raised. We conclude that no reliable conclusions can be made concerning the subclass ratio in biological fluids unless the monoclonal antibodies used have been appropriately validated.

Triglyceride-rich lipoproteins of subjects heterozygous for apolipoprotein E2(Lys146-->Gln) are inefficiently converted to cholesterol-rich lipoproteins.

The APOE*2(Lys146-->Gln) allele behaves like a dominant trait in the expression of familial dysbetalipoproteinemia (FD) (Smit et al., J. Lipid Res. 1990; 31: 45-53). FD patients carrying the APOE*2(Lys146-->Gln) allele exhibit less elevated cholesterol to triglyceride ratios in the d < 1.019 g/ml lipoprotein density fraction as compared to classical FD patients displaying homozygosity for the APOE*2(Arg158-->Cys) allele (0.8 vs. 1.4). Upon treatment of complete serum with lipoprotein lipase (LPL), the mean cholesterol to triglyceride molar ratio of the d < 1.019 g/ml lipoprotein fraction in these FD patients increased only marginally (from 0.8 to 1.1), as compared with that of classical FD subjects (from 1.4 to 2.6) and non-FD control subjects (from 0.7 to 1.5). In order to obtain further evidence for an inefficient lipolysis of the d < 1.019 g/ml lipoprotein fraction in APOE*2(Lys146-->Gln) carriers, possibly in combination with a less efficient cholesteryl ester transfer protein (CETP) activity, blood samples of APOE*2(Lys146-->Gln) allele carrying FD patients were analysed and compared with classical FD patients and controls. In the APOE*2(Lys149-->Gln) allele carrying FD patients were analysed and compared with classical FD patients and controls. In the APOE*2(Lys146-->Gln) FD patients, the increase in plasma cholesterol was mainly confined to the very low density lipoprotein (VLDL) fraction, whereas in classical FD patients, the levels of cholesterol in the intermediate density lipoprotein (IDL) fraction was also dramatically increased (ratios of VLDL to IDL cholesterol are 4.7 and 2.6, respectively). Family analyses of the APOE*2(Lys146-->Gln) FD subjects showed that the apo E to apo B ratio in the d < 1.019 g/ml lipoprotein fraction of allele carriers is 3.5 times as high as that found in non-carriers (2.8 vs. 0.8, by wt.). Also, in the APOE*2(Lys146-->Gln) allele carrying family members, the ratio of cholesterol to triglyceride of the d < 1.019 g/ml lipoprotein fraction is less markedly elevated upon addition of LPL when compared to that in non-carrying controls (from 1.1 to 1.8 vs 0.7 to 1.6). The efficiency of the d < 1.019 g/ml lipoprotein fraction of APOE*2(Lys146-->Gln) FD patients to compete with low density lipoprotein (LDL) for binding to the LDL receptor is intermediate to that of controls and classical APOE*2(Arg158-->Cys) homozygous FD patients. These findings suggest that in APOE*2(Lys146-->Gln) allele carriers, the conversion of VLDL into IDL is impaired due to an inefficient lipolysis, possibly in combination with a retarded CETP activity.(ABSTRACT TRUNCATED AT 250 WORDS)

"I'll do it when the snow melts": The effects of deadlines and delayed outcomes on rule-governed behavior in preschool children.

This study examined the control exerted by different types of rules on the behavior of preschool children. Four similar rules were presented to eight, four-year-old children, using a multielement design. The contingencies the rules described varied in the specification of deadlines and in the delays in the delivery of the reinforcers. The results showed (a) rules specifying only response requirements did not reliably control behavior, (b) rules specifying an immediate deadline with the immediate delivery of a reinforcer exerted reliable control, (c) rules specifying an immediate deadline with a one-week delay in the delivery of the reinforcer also exerted reliable control, and (d) rules specifying no deadline with a one-week delay in the delivery of the reinforcer exerted little control. These results suggest that a rule's specification of a deadline is crucial in its control of behavior, but the delay of the reinforcer is of little importance. This latter conclusion further suggests that problems in self-control do not result from delayed outcomes or the inablity to delay gratification, contrary to conventional wisdom.