Species-related innate resistance to Schistosoma mansoni. Role of mononuclear phagocytes in schistosomula killing in vitro.

Resistance to infection with the multicellular parasite Schistosoma mansoni has been previously demonstrated to vary among several host species. The current investigation was designed to examine the basis for this species-related resistance in vitro. Adherent peritoneal macrophages or peripheral blood mononuclear cells from several species of host animals were incubated with S. mansoni schistosomula for 18-24 h; parasite viability was then assayed by methylene blue exclusion. Peritoneal exudate macrophages from susceptible species, such as mice (C57Bl/6) and hamsters killed, respectively, 6.6 +/- 2 and 8.0 +/- 2% of incubated schistosomula. In contrast, cells from resistant species: rats, guinea pigs, and rabbits, killed 21 +/- 2.3, 15 +/- 4.6, and 17 +/- 5.5%, respectively. Furthermore, blood monocytes from rabbits resulted in a mean of 25.9 +/- 2.8% dead organisms. Schistosomula killing by mononuclear phagocytes obtained from resistant species (rats or rabbits) was dependent on the cell/parasite ratio. Significant schistosomula mortality resulted from culture supernatants of rat macrophages or rabbit monocytes. Killing by cells from both species was significantly reduced upon addition of L-arginine, while catalase reduced killing only by rat macrophages. We conclude that mononuclear phagocytes may play a key role in species-related innate resistance to schistosomiasis; their in vitro schistosomulicidal activity parallels the known in vivo susceptibility of the donor species. Killing is mediated by lysosomal enzymes (arginase) and by products of oxidative metabolism, the predominant mechanism depends on the specific animal species.

Musculoskeletal-related disability in US Army personnel: prevalence, gender, and military occupational specialties.

Research on military populations indicates that musculoskeletal-related disorders represent a prevalent source of outpatient visits, lost work time, hospitalization, and disability. Despite the increasing role of women in the military, little is known regarding the association among military occupations, gender, and disability. The study presented here analyzed 41,750 disability cases to determine: (1) prevalence of work-related musculoskeletal disability, (2) specific jobs associated with greater risk of musculoskeletal disability, and (3) association among gender, job-type, and disability. Results indicate: (1) back-related disorders represent the most prevalent sources of disability, (2) certain occupations were associated with higher disability risk, (3) women experienced higher overall, and musculoskeletal, disability risk, and (4) specific jobs were identified in which women experienced higher rates of musculoskeletal disability. These findings highlight the need to consider the interaction between workplace factors and gender on disability in the military work force.

Occupational upper-extremity-related disability: demographic, physical, and psychosocial factors.

Occupational upper-extremity disorders have been associated with prolonged pain and work disability. Using the U.S. Army Physical Disability Agency database, the present case-control studies (n = 434 and n = 342) investigated the contribution of demographic, physical, occupational psychosocial, and individual psychosocial factors to work disability in soldiers with upper-extremity disorders. Age (odds ratio [OR] = 1.11), rank (private E-2: OR = 3.79; private first class: OR = 4.39; specialist or corporal: OR = 2.17), ethnic group (white: OR = 1.54), and occupational stress ("often": OR = 2.46) were found to predict disability. The results highlight the importance of occupational stress as a predictor of disability and the potential utility of addressing this factor in the development of empirically based disability prevention strategies. This investigation also emphasizes the need for research that delineates the biobehavioral mechanisms linking occupational stress to prolonged symptoms and subsequent work disability.

Occupational back disability in U.S. Army personnel.

Musculoskeletal disorders represent a prevalent source of outpatient visits, lost work time, hospitalization, and disability in the military. Recent research has identified patterns among military occupations, gender, and musculoskeletal disability. Although back disorders accounted for a high percentage of all cases, little is known about the relationship between job type and disability in soldiers. The present study analyzed 41,750 disability cases to determine (1) prevalence of work-related back disability diagnoses, (2) specific jobs associated with greater risk of back disability, and (3) association among gender, job type, and disability. The results indicate that (1) lumbosacral strain and intervertebral disc syndrome represent the most prevalent diagnoses for back disability, (2) certain occupations were associated with higher back disability risk, and (3) specific jobs were identified in which females experienced higher rates of back disability than males. The nature of these high-risk jobs, and recent research on work disability factors in U.S. Army soldiers, suggest that a combination of ergonomic and individual/organizational psychosocial factors may play a role in the development, exacerbation, and maintenance of work disability. Future research that identifies specific job factors contributing to increased back disability risk should assist in the development of empirically based work site prevention programs to improve musculoskeletal health and readiness.

Teaching prevocational skills to EMR adolescents.

A program for strengthening promptness and initiative behaviors was conducted with three educable, mentally retarded adolescents. The program consisted of three elements: (a) instructions on the responses desired and their importance, (b) a self-evaluation procedure, and (c) consequation of successful performance with social praise from the classroom teacher. The results supported the efficacy of the intervention package as a method for teaching two behaviors that are commonly emphasized in prevocational and vocational special education curricula.

Increasing implementation of special education instruction in mainstream preschools: direct and generalized effects of nondirective consultation.

Two studies evaluated a consultation strategy for increasing teachers' implementation of instruction related to specific Individualized Education Plan objectives for handicapped children mainstreamed into regular preschool programs. In the first study, teachers viewed videotaped sequences of regular classroom routines and were asked to generate ideas for embedding IEP-related instruction into those routines. All teachers demonstrated increases in instructional behaviors in targeted routines, and 2 of the 3 teachers increased instruction in additional settings that had not been the focus of the consultation. Children demonstrated concomitant increases in IEP-targeted behaviors. In follow-up questionnaires and interviews, teachers reported increased confidence in their ability to implement specialized instruction. These findings were replicated in a second study in which the videotaping was replaced by teacher interview, and in which the consultation was carried out by a previously untrained special education teacher.

To be or not to be? How hospitals and doctors should decide whether to reinvest in or divest of their group practices.

Do you have a physician-hospital partnership that's bleeding red ink? How do you decide whether to divest or reinvest in it? Here are some guidelines and considerations to help you choose.

Effects of contextual conditioning and unconditional stimulus presentation on performance in appetitive conditioning.

Four experiments with rat subjects examined the effects of contextual conditioning on conditioned appetitive performance. Experiment 1 compared the effects of contextual conditioning on performance to conditioned stimuli (CSs) with different conditioning histories. Contextual conditioning enhanced performance to the CS if the CS had first been conditioned and then extinguished, but had no effect on performance when the CS had been merely paired or unpaired with food. Experiments 2 and 3 then asked whether the effect on the extinguished CS was due to contextual conditioning acting as a cue for conditioning. In Experiment 2, extinction procedures in which extra unconditioned stimuli (USs) were presented during the intertrial intervals were found to reduce the CS's sensitivity to enhancement by contextual conditioning, but had no effect on spontaneous recovery. In Experiment 3, USs added to conditioning or extinction acquired the ability to cue the corresponding performance. Under some conditions, USs added to conditioning could suppress performance (Experiment 4). The results suggest that contextual conditioning has complex effects that can be better understood by recognizing that contextual conditioning, as well as the USs that create it, may acquire discriminative control over conditioned responding.

Modulation of human neutrophil effector functions by monoclonal antibodies against surface membrane molecules of 94,000 and 180,000 molecular weight.

Function-related antigens on the neutrophil (PMN) surface were identified using two newly developed PMN-specific mouse monoclonal antibodies. These IgG antibodies, designated Ab 1-14 and Ab 1-15, were selected for detailed study after initial testing revealed their significant inhibition of PMN superoxide generation in response to N-formyl-Met-Leu-Phe (FMLP) (64% for 1-14 and 64% for 1-15; P less than .05). In further experiments, Ab 1-14 augmented PMN adhesion (by 111%; P less than .01) and degranulation (by 52%; P less than .05) in response to FMLP, while Ab 1-15 inhibited these responses by 42% and 29%, respectively (P less than .05). Ab 1-14 reduced PMN chemotaxis in response to FMLP by 37% (P less than .02), and unlike Ab 1-15, Ab 1-14 significantly reduced unstimulated PMN binding of complement-coated sheep red blood cells. Ab 1-14 and Ab 1-15 significantly reduced PMN superoxide production in response to phorbol myristate acetate (PMA) (14% and 23%, respectively; P less than .05). Whereas 1-14 was found to increase PMA-induced cell degranulation significantly (175%), Ab 1-15 did not alter degranulation response to PMA. Immunoprecipitation showed that Ab 1-14 and Ab 1-15 recognized respective surface antigens of 94,000 mol wt and 130,000 to 180,000 mol wt. Our findings suggest that the surface molecules identified by these two monoclonal antibodies play a significant role in neutrophil activation by both FMLP and PMA.

A prospective study of Chlamydia pneumoniae infection and risk of MS in two US cohorts.

BACKGROUND: Chlamydia pneumoniae (Cpn) has been proposed as a possible etiologic agent in multiple sclerosis (MS). However, previous studies were cross-sectional and could not assess whether Cpn infection preceded the onset of MS. METHODS: The authors conducted a prospective nested case-control study among 3 million US Army personnel and 121,466 members of the Kaiser Permanente Medical Care Program (KPMCP) cohort. Serum samples collected prior to onset of MS symptoms were available for 83 MS cases in the Army and 46 in the KPMCP cohort. Two controls were matched to each case on age, sex, and date of blood collection. Microimmunofluorescence was used to measure serum immunoglobulin M (IgM) and immunoglobulin G (IgG) antibody titers to Cpn; IgG titers > or 1:16 were considered positive for past Cpn infection. RESULTS: Seropositivity for Cpn was not significantly associated with risk of MS in either cohort (Army: OR = 1.0; 95% CI 0.6, 1.8; KPMCP: OR = 1.5; 95% CI 0.7, 3.1) or in the pooled analysis (OR = 1.2; 95% CI 0.8, 1.9). Serum levels of anti-Cpn IgG antibody were also not associated with an increased risk of MS in the Army (OR for a fourfold difference in antibody titers = 0.9; 95% CI 0.7, 1.2) or in the pooled analysis (OR = 1.2; 95% CI 0.9, 1.4), but a significant increase in risk was seen in the KPMCP cohort (OR = 1.7; 95% CI 1.2, 2.5). The difference between these results in the Army and the KPMCP cohort was significant (p = 0.01). CONCLUSIONS: Neither Cpn seropositivity nor serum anti-Cpn IgG antibody titers predicted risk of developing MS. However, due to the heterogeneity of results between cohorts, we cannot exclude the possibility that infection with Cpn may modify the risk of MS.