Identification and expression of macrophage migration inhibitory factor in Sarcoptes scabiei.

Macrophage migration inhibitory factor (MIF) is a pleiotropic proinflammatory cytokine produced by many mammalian tissues including skin. It is also found in many invertebrate parasites of mammals including ticks and may function to aid the parasite to evade the innate and adaptive immune responses in the host. In this study, the cDNA for a MIF gene was sequenced from Sarcoptes scabiei, the scabies mite, using RT-PCR and RACE molecular techniques. The resulting nucleotide sequence had a length of 405 base pairs and the putative amino acid sequences for the mite and tick (Dermacentor variabilis) proteins were identical. The initial steps for the project resulted in the production of expressed scabies mite cDNAs. A real time (qPCR) assay was performed with MIF from scabies mites and various tick species. Results show that mRNA encoding MIF homologues was three times more abundant in the mite samples when compared to RNA prepared from D. variabilis salivary glands and 1.3 times more abundant when compared with RNA prepared from D. variabilis midgut.

Effects of establishment method and fall stocking rate of wheat pasture on forage mass, forage chemical composition, and performance of growing steers.

Stocking rate is a fundamental variable for managing pastures, and there is a distinct relationship between stocking rate and animal performance for each forage type. This research was conducted to determine the effects of fall stocking rate (SR) and method of establishment of wheat pasture planted into dedicated crop fields on animal performance during the fall and subsequent spring. There was a factorial arrangement of tillage methods used in the establishment of wheat pasture and fall stocking rates. Tillage treatments included 1) CT, seed sown into a prepared seedbed, 2) RT, a single pass with a light disk followed by broadcasting of seed, or 3) NT, direct seeding into the undisturbed stubble of the grazed-out wheat pasture from the previous year. The fixed SR during the fall were 1.9, 2.5, and 3.7 growing beef steers (Bos taurus L.)/ha. In the spring all pastures were grazed at the same fixed SR by steers for graze out. Data were analyzed using the mixed procedure of SAS as a randomized complete block design with field as the experimental unit and year as the block. Forage mass, forage nutritive composition, and animal performance during the fall or spring were not affected (P ≥ 0.14) by tillage method. During the fall grazing season, with increasing SR there were linear (P < 0.01) decreases in BW of steers upon removal from pasture, BW gain per steer, and ADG, whereas grazing-day per hectare and BW gain per hectare increased linearly (P < 0.01) with increasing SR. The carryover effects of fall SR into the spring grazing season decreased (P< 0.01) grazing-day per hectare and tended (P ≤ 0.09) to produce quadratic changes in BW upon removal from pasture and BW gain per hectare. Across the fall and spring grazing seasons, grazing-day per hectare increased linearly (P < 0.01) with greater SR, and BW gain per hectare increased quadratically (P = 0.02) with increased fall SR. A tillage treatment by fall SR interaction (P = 0.10) indicates that although there was no difference (P ≥ 0.12) due to tillage treatment in BW gain per hectare at 1.9 or 2.5 SR, NT fields produced (P ≤ 0.04) more BW gain per hectare than CT or RT at the 3.7 SR. Although increasing SR of growing steers leads to reduced animal performance in the fall and reduced carrying capacity in the spring, NT appears to be capable of withstanding greater fall SR with less impact on total production per hectare than CT or RT.

Diagnosis and management of necrotising fasciitis: a multiparametric approach.

Necrotising fasciitis (NF) is situated with myositis and myonecrosis at the severe end of a spectrum of skin and soft tissue infections but is far removed from erisepelas, impetigo and cellulitis. Inexperienced clinicians are easily misled by the protean manifestations of infection, especially exotoxin or superantigen mediated consequences from streptococcal NF. Early clinical suspicion and surgery are key to improving survival, and patients with NF need integrated multidisciplinary management, adjusted to the infecting organism(s), the site of infection, and the effects from any toxins produced. A multiparametric approach, incorporating various clinical and laboratory parameters, can aid aggressive management. This review describes the diagnosis and management of the major types of NF, emphasising important aetiological clues from the history and the appropriate usage of diagnostic investigations. The potential benefits of controversial therapeutic approaches, including hyperbaric oxygen and intravenous immunoglobulin, are discussed.

Diagnosis and treatment of Panton-Valentine leukocidin (PVL)-associated staphylococcal pneumonia.

Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus is emerging as a serious problem worldwide. Whilst usually causing skin and soft-tissue infections, particularly recurrent abscesses, there has in the last 10 years been an increase in the incidence of an associated devastating pneumonia affecting previously healthy young people and associated with a very high mortality. There are no evidence-based guidelines to consult for the management of PVL-associated staphylococcal pneumonia. The literature contains less than 100 cases, with widely differing antimicrobial therapies and the occasional use of other adjunctive therapies such as intravenous immunoglobulin, activated protein C and extracorporeal membrane oxygenation. This literature review focuses on the salient features of diagnosis and management, with particular attention to the choice of antimicrobials.

A physiologically based toxicokinetic model of inhalation exposure to xylenes in Caucasian men.

Widespread exposure to the volatile aromatic hydrocarbons, ortho-, meta-, and para-xylene occurs in many industries including the manufacture of plastics, pharmaceuticals, and synthetic fibers. This paper describes the development of a physiologically based toxicokinetic model using biomonitoring data to quantify the kinetics of ortho-, meta-, and para-xylenes. Serial blood concentrations of deuterium-labeled xylene isomers were obtained over 4 days after 37 controlled, 2h inhalation exposures to different concentrations of the isomers. Peak toxicant concentrations in blood occurred in all subjects at the termination of exposure. Systemic clearance averaged 116 L/h+/-34 L/h, 117 L/h+/-23 L/h, and 129 L/h+/-33 L/h for ortho-, para-, and meta-xylene, respectively. The half-life of each toxicant in the terminal phase (>90 h post-exposure) was fit by the model, yielding values of 30.3+/-10.2 h for para-xylene, 33.0+/-11.7 h for meta-xylene and 38.5+/-18.2 h for ortho-xylene. Significant isomeric differences were found (p<0.05) for toxicant half-life, clearance and extrahepatic metabolism. Inter-individual variability seen in this study suggests that airborne concentration guidelines may not protect all workers. A Biological Exposure Index is preferred for this purpose since it is integrative and reflective of inter-individual kinetic variability.

Characterization of allergens of Anisakis simplex.

BACKGROUND: Anisakis simplex is an intestinal parasite of sea mammals. The larvae infect crustaceans, cephalopods and fish. Humans may consume A. simplex third stage larvae (L3) when eating infected raw or under-cooked fish. Consumed larvae cause an inflammatory reaction when they penetrate the digestive mucosa. The larvae or their secretory/excretory products can sensitize humans and induce an immunoglobulin E (IgE)-mediated allergic reaction. This parasite is now being implicated in numerous cases of allergic reactions after eating fish. The purpose of this study was to evaluate the allergenicity of proteins present in an extract of the third stage larva. METHODS: Rabbit antiserum raised to A. simplex somatic extract (L3) was reacted by crossed immunoelectrophoresis (CIE) with the same somatic extract. Crossed radioimmunoelectrophoresis (CRIE) was also performed by incubating CIE gels first in the sera of 13 individuals with positive immunoCAP to A. simplex and then in radiolabeled anti-human IgE. RESULTS: Twelve to 16 antigen-antibody precipitin peaks were visualized on Coomassie blue stained CIE gels in which somatic extract was reacted with somatic-antiserum. Autoradiography of CRIE gels showed that 18 different proteins bound IgE in patient sera. Individual patients had serum IgE directed at two to 10 different allergens. Five of these allergens were recognized by >/=50% of the patients. No allergen was recognized by every patient and no patient had serum IgE directed at all 18 allergens. CONCLUSION: Somatic extracts of A. simplex L3 larva contain a large number of allergenic molecules and there is significant variability between patients in their sensitivity and reactivity to these allergens.

Distribution and removal of cat, dog and mite allergens on smooth surfaces in homes with and without pets.

BACKGROUND: Removing allergen from the indoor environment should be a primary strategy for the management and treatment of allergic disease. OBJECTIVE: The aims of this study were to characterize the distribution of dog, cat, and mite allergen on hard surfaces in homes with and without pets and to evaluate the efficiency of removing allergen from hard surfaces by wiping with a dry dust cloth and by vacuum cleaning using the dustbrush attachment. METHODS: The amount of allergen collected from adjacent areas of two smooth floors, a wall, and finished furniture by wiping with a Pledge Grab-it dust cloth (S. C. Johnson & Son, Inc, Racine, WI) and by brush-vacuuming were compared for 24 homes with and without pets. In addition, the areas first wiped with the dust cloth were then brush-vacuumed and the amounts of allergen collected by the first and second cleaning were compared. RESULTS: A key finding was that 23 of the 24 homes had Can f 1 allergen on one or more of the sampled areas regardless of whether a dog was present. Most homes with pets and many homes without pets had Can f 1 and Fel d 1 allergens on walls, smooth floors, and finished furniture. Carpets were the major reservoir for pet allergens in homes with pets whereas allergen was more uniformly distributed in homes without pets. Little mite allergen was found on hard surfaces even when it was present in carpets. CONCLUSIONS: Dog and cat allergens are prevalent on walls, smooth floors, and finished furniture in homes with and without pets. Dry dusting with a Grab-it dust cloth was an effective cleaning method for removing allergen from hard smooth surfaces.

Characterization of house dust mite and scabies mite allergens by use of canine serum antibodies.

OBJECTIVE: To identify the major allergenic proteins from the 3 main species of dust mites to which dogs react (Dermatophagoides farinae, D. pteronyssinus, and Euroglyphus maynei) and evaluate the potential cross-reactivity of dust mite allergens with antigens from the ectoparasitic mite Sarcoptes scabiei var canis. SAMPLE POPULATION: Sera from 83 dogs with atopic dermatitis. PROCEDURE: Sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting using serum from atopic dogs was used to identify IgE-binding proteins in extracts of the 4 mite species. RESULTS: Sera of atopic dogs contained IgE against 23, 17, 25, and 17 allergens from D. farinae, D. pteronyssinus, E. maynei, and S. scabiei, respectively. Unlike the situation for humans, the major allergens for dogs are mostly proteins that are larger than 90 kd molecular weight. Dermatophagoides farinae and E. maynei appear to be more allergenic for dogs than is D. pteronyssinus. Some dogs with serum IgE against dust mites also had IgE against antigens of S. scabiei var canis. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple dust mite allergens induce an IgE response in dogs. These allergens are mostly greater than 90 kd molecular weight.

Reducing relative humidity is a practical way to control dust mites and their allergens in homes in temperate climates.

BACKGROUND: Maintaining a relative humidity (RH) of less than 50% is one recommendation for reducing numbers of house dust mites and their allergens in homes. OBJECTIVE: The purpose of this study was to determine whether, in a humid temperate climate, indoor RH could be sufficiently lowered to control dust mites and their allergens. METHODS: During a period spanning 2 humid summers (May 1998 to October 1999), dust mite and allergen densities were determined in 3 groups of homes. One group (low RH group, n = 23) maintained an RH of less than 51%. Most of these homes used a high-efficiency dehumidifier and air conditioning. A second group of homes (group A) used air conditioning only (n = 19) or air conditioning and dehumidification (n = 5) but did not maintain an RH of less than 51%. A third group of homes (group C, n = 24) controlled climate by opening windows and had an RH of greater than 51%. Normal housecleaning was maintained in all homes during the study. RESULTS: The low RH group homes started in June with a mean +/- SE of 401 +/- 124 live mites and 17 +/- 3 microg of total Der 1 allergen per gram of dust. After 17 months of maintaining an RH of less than 51%, these declined significantly to 8 +/- 3 live mites per gram (P =. 004) and 4 +/- 1 microg of Der 1 per gram of dust (P <.001). In contrast, group A and C homes exhibited seasonal peaks of 500 to 1000 mites and 40 to 70 microg of Der 1 per gram of dust. At all time points after the baseline sample, the low RH group homes had significantly less (P <.001) allergen than the group A and C homes. After 17 months, allergen levels were more than 10 times lower in low RH homes compared with humid homes. CONCLUSION: This study showed that it is practical to maintain an indoor RH of less than 51% during the humid summer season in a temperate climate, and this resulted in significant reductions in mite and allergen levels.

Investigation of postanginal sepsis and Lemierre's syndrome in the South West Peninsula.

We describe a retrospective case series of postanginal sepsis and Lemierre's syndrome (LS) identified from laboratory records of Fusobacterium necrophorum isolates and from clinical case note review. Some patients presented with sore throat, tonsillitis, quinsy or a septicaemic illness, whereas others presented with symptoms related to metastatic septic lesions with later recognition of the significance of the preceding sore throat. Patients with otitis media and mastoiditis are included in the study. The incidence of postanginal sepsis and LS appears to have increased over the study period (1994-99). The population of patients who had received antibiotics pre-admission has decreased in recent years. Attention is drawn to features which may assist in differentiating this condition from simple viral sore throats not requiring antibiotic therapy. A prospective study of the incidence of this rare but life-threatening condition mainly affecting young people is required in view of the more restricted use of antibiotic treatment for sore throat now recommended.

Serum antibody to Sarcoptes scabiei and house dust mite prior to and during infestation with S. scabiei.

In this study, serum antibodies to Sarcoptes scabiei var. canis (SS), Dermatophagoides farinae (DF), and D. pteronyssinus (DP) were determined in 19 healthy, random-source dogs prior to infestation with scabies then again during a primary infestation, cure and challenge infestation with scabies. Prior to scabies infestation, serum of 11 dogs contained faintly detectable amounts of IgE and/or IgG to proteins in SS extract, probably resulting from sensitization to dust mites that share cross-reactive antigenic epitopes with SS. After becoming infested with scabies, the response to SS antigens became stronger with antibodies appearing to more antigens as the scabies infestation progressed. Three of the newly recognized proteins were 170, 155 and 142/133kD and could be used in a diagnostic test since antibodies to them appeared during the primary infestation. In addition, during the primary infestation, 14 of 15 dogs developed IgE to 1-11 new SS proteins in addition to an increase in IgE binding to those proteins recognized prior to infestation. Overall, the strongest antibody responses (IgE and IgG) were exhibited during cure of the first infestation, when dead mites were still present in the stratum corneum. As expected, the antibody response was strong and rapid during challenge when the infestation self-cured. The immunogenic SS proteins identified by serum antibody binding during challenge, when the hosts self-cured, are candidates for inclusion in a vaccine. These candidate proteins are 200, 185, 170, 155, 142/133, 112, 97, 74, 57, 45/42, 32 and 22kD. Some of the proteins in SS that exhibited new or increased antibody binding during the experiment also had IgE and IgG binding to proteins with similar molecular weights in DF and DP extracts. These results illustrate the difficulties involved in understanding and interpreting serum antibody for developing a serological test for the diagnosis of scabies, isolating relevant SS antigens that could be included in a vaccine for prevention of scabies, and for understanding the immune response mechanism to scabies.

An analysis of criteria for biological limit values developed in Germany and in the United States.

The biological tolerance values established by the German Research Foundation and the biological exposure indices developed by the American Conference of Governmental Hygienists represent two extensive lists of occupational exposure guidelines for use in biological monitoring. Although there is substantial agreement between the two organizations on most points, there are several important differences in the approaches taken in setting of the guideline values. Analysis of these distinctions serves to focus attention on the current issues impeding international agreement over occupational exposure guidelines. Among these issues are (1) the specification of the biological monitoring guidelines as ceiling or average values; (2) whether carcinogenic substances should be treated differently from agents with other toxic outcomes; (3) the method of accounting for variability among individual workers; and (4) the extent to which these guidelines should be extended to include genetic markers, indicators of susceptibility, or indicators of early biological response.

Exposures to wood dust in U.S. industries and occupations, 1979 to 1997.

BACKGROUND: We analyzed 1,632 measurements of airborne wood dust reported to OSHA's Integrated Management Information System in the period 1979 to 1997. METHODS: The relationships between wood dust concentrations and various factors documented in the OSHA database were examined in a multiple regression model. RESULTS: Exposures ranged from less than 0.03 to 604 mg/m3, with an arithmetic mean of 7.93 and a geometric mean of 1.86. Reported exposure levels decreased substantially over time (e.g., unadjusted geometric mean in 1979 = 4.59 mg/m3; in 1997 = 0.14 mg/m3). High exposure jobs included sanders in the transportation equipment industry (unadjusted geometric mean = 17.5 mg/m3), press operators in the wood products industry (12.3 mg/m3), lathe operators in the furniture industry (7.46 mg/m3), and sanders in the wood cabinet industry (5.83 mg/m3). CONCLUSIONS: In the multiple regression model, year, state, job, and industry were found to be predictors of exposure. Year and state were likely surrogates for other factors which directly influence exposure, but which were not included in the IMIS database, such as the use of engineering control measures.

A comparison of 1H8- and 2H8-toluene toxicokinetics in men.

1. To examine the bioequivalence of an isotope-labelled tracer to study toxicant disposition, we conducted 33 controlled human exposures to a mixture of 50 ppm 1H8-toluene and 50 ppm 2H8-toluene for 2 h, and measured concentrations in blood and breath, and metabolite levels in urine for 100 h post-exposure. 2. A physiologically based kinetic (PBK) model found that compared with 1H8-toluene, 2H8-toluene had a 6.4+/-13% (mean+/-SD) lower AUC, a 6.5+/-13% higher systemic clearance (1.46+/-0.27 versus 1.38+/-0.25 l/h-kg), a 17+/-22% larger terminal volume of distribution (66.4+/-14 versus 57.2+/-10 l/kg) and a 9.7+/-26% longer terminal half-life (38+/-12 versus 34+/-10 h) (p < 0.05 for all comparisons). 3. The higher 2H8-toluene clearance may have been due to an increased rate of ring oxidation, consistent with the 17% higher observed fraction of 2H5- versus 1H5-cresol metabolites in urine. 4. The larger terminal volume and half-lives for 2H8-toluene suggested a higher adipose tissue/blood partition coefficient. 5. Observed isotope differences were small compared with interindividual differences in 1H8-toluene kinetics from previous studies. 6. The PBK model allowed us to ascribe observed isotope differences in solvent toxicokinetics to underlying physiologic mechanisms.

Allergenicity of the mite Hemisarcoptes cooremani.

BACKGROUND: A researcher experienced allergic symptoms while working with the astigmatid mite Hemisarcoptes cooremani cultured on scale insects. This mite is a predator of scale insects that often parasitize many perennial vascular plants in orchards, gardens, and ornamental nurseries worldwide; therefore, orchard and ornamental nursery workers and gardeners may be exposed to this mite. OBJECTIVE: We investigated the possible allergenicity of H. cooremani and the cross-reactivity between it and other allergy-causing astigmatid mites. METHODS: Serum from a subject who experienced allergic symptoms while working with H. cooremani was analyzed for IgE and IgG to proteins in an extract of this mite and of other astigmatid mites known to cause allergic reactions. The serum was used to probe proteins fractionated by SDS-PAGE or precipitated by CIE using rabbit antiserum. In addition, the subject's serum was used to directly precipitate proteins in extracts of H. cooremani and other mite species. RESULTS: SDS-PAGE and immunoblotting of proteins in an H. cooremani extract showed the reference serum contained IgE directed at 16-kD and 19-kD proteins. Crossed radioimmunoelectrophoresis reaction showed that the subject's serum contained antibody that precipitated a protein in an H. cooremani extract and that IgE bound to this protein. The proteins in an extract of H. cooremani did not precipitate when reacted with rabbit antisera against the dust mites D. farinae, D. pteronyssinus, and E. maynei, or the storage mites B. tropicalis, L. destructor, and T. putrescentiae. This indicated there was no cross-reactivity between H. cooremani and these mites. CONCLUSION: These results indicated that an extract of the mite H. cooremani contained at least two prominent IgE binding proteins that were not present in the other astigmatid mites. Thus, H. cooremani is the source of unique allergenic proteins and allergy to this mite may develop in orchard and ornamental nursery workers and gardeners.

Reproductive endocrine effects of acute exposure to toluene in men and women.

OBJECTIVES: Despite observation of adverse reproductive effects of toluene, including alterations of serum gonadotropins (luteinising hormone (LH) and follicle stimulating hormone (FSH)) in humans, little is known of the mechanism of toxicity. The hypothesis was tested that toluene acutely suppresses pulsatile gonadotropin secretion by measuring LH and FSH at frequent intervals during controlled exposure to toluene. METHODS: Women in the follicular and luteal phases of the menstrual cycle and men were randomised to inhale filtered air with or without 50 ppm toluene through a mouthpiece for 3 hours (19% of the OSHA permissible exposure limit). Blood was sampled by intravenous catheter at 20 minute intervals for 3 hours before, 3 hours during, and 3 hours after exposure. Plasma LH, FSH, and testosterone were measured. Pulse amplitude, pulse frequency, and mean concentrations of LH and FSH for each of the 3 hour periods before, during and after exposure to toluene versus sham exposure were calculated with the ULTRA pulse detection program and compared by analysis of variance (ANOVA) with repeated measures. RESULTS: In men mean concentrations of LH showed a significant interaction (p < 0.05) between exposure and sampling period, with a greater LH decline during exposure to toluene than sham exposure. However, there was no concomitant effect on testosterone concentrations. The LH pulse frequency of women in the luteal phase showed a trend towards a significant interaction between exposure and sampling period (p = 0.06), with a greater decline in pulse frequency during exposure to toluene than sham exposure. There were no other significant effects of exposure to toluene. CONCLUSIONS: Three hour exposure to 50 ppm toluene did not result in abnormal episodic LH or FSH secretion profiles, however, subtle effects on LH secretion in men and women in the luteal phase were found. The clinical relevance of these effects is unclear, indicating the need for further study of reproductive function in exposed workers.

Individual prior information in a physiological model of 2H8-toluene kinetics: an empirical Bayes estimation strategy.

Physiologically-based toxicokinetic (PBTK) models are widely used to quantify whole-body kinetics of various substances. However, since they attempt to reproduce anatomical structures and physiological events, they have a high number of parameters. Their identification from kinetic data alone is often impossible, and other information about the parameters is needed to render the model identifiable. The most commonly used approach consists of independently measuring, or taking fom literature sources, some of the parameters, fixing them in the kinetic model, and then performing model identification on a reduced number of less certain parameters. This results in a substantial reduction of the degrees of freedom of the model. In this study, we show that this method results in final estimates of the free parameters whose precision is overestimated. We then compared this approach with an empirical Bayes approach, which takes into account not only the mean value, but also the error associated with the independently determined parameters. Blood and breath 2H8-toluene washout curves, obtained in 17 subjects, were analyzed with a previously presented PBTK model suitable for person-specific dosimetry. Model parameters with the greatest effect on predicted levels were alveolar ventilation rate QPC, fat tissue fraction VFC, blood-air partition coefficient Kb, fraction of cardiac output to fat Qa/co and rate of extrahepatic metabolism Vmax-p. Differences in the measured and Bayesian-fitted values of QPC, VFC and Kb were significant (p < 0.05), and the precision of the fitted values Vmax-p and Qa/co went from 11 +/- 5% to 75 +/- 170% (NS) and from 8 +/- 2% to 9 +/- 2% (p < 0.05) respectively. The empirical Bayes approach did not result in less reliable parameter estimates: rather, it pointed out that the precision of parameter estimates can be overly optimistic when other parameters in the model, either directly measured or taken from literature sources, are treated as known without error. In conclusion, an empirical Bayes approach to parameter estimation resulted in a better model fit, different final parameter estimates, and more realistic parameter precisions.