Job exposure matrices for occupational respiratory disease: a narrative review.

BACKGROUND: Job exposure matrices (JEMs) are epidemiological tools used to provide estimations of occupational exposures when it is not feasible to complete detailed individual occupational histories. AIMS: To identify and summarize the characteristics of published general population JEMs (GPJEM) of inhalable occupational exposures applied in studies of respiratory disease. METHODS: MEDLINE and EMBASE databases were searched using pre-defined search terms, with screening performed by two independent reviewers to identify studies reporting the use of a GPJEM. JEM creation papers were subsequently identified and reviewed for each individual GPJEM, noting its characteristics in terms of occupational classification system and exposure estimates. RESULTS: From 728 studies identified in initial searches, 33 GPJEMs of inhalable occupational exposures were identified. Versions of the International Standards Classification of Occupations were the most used occupational classification system. Binary, probability and intensity-based exposure estimates were most frequently reported in GPJEMs. CONCLUSIONS: Selection of a GPJEM to apply in epidemiological research should be based on the exposure(s) of interest, time period of occupations under review, geographical region for intended use, occupation classification system used and the exposure estimate outcome.

Occupational asthma in office workers.

BACKGROUND: Office work has a relative perception of safety for the worker. Data from surveillance schemes and population-based epidemiological studies suggest that office work carries a low risk of occupational asthma (OA). Office workers are frequently used as comparators in studies of occupational exposure and respiratory disease. AIMS: We aimed to describe and illustrate our tertiary clinical experience of diagnosing OA in office workers. METHODS: We searched the Birmingham NHS Occupational Lung Disease Service clinical database for cases of occupational respiratory disease diagnosed between 2002 and 2020, caused by office work or in office workers. For patients with OA, we gathered existing data on demographics, diagnostic tests including Occupational Asthma SYStem (OASYS) analysis of serial peak expiratory flow and specific inhalational challenge, and employment outcome. We summarised data and displayed them alongside illustrative cases. RESULTS: There were 47 cases of OA (5% of all asthma) confirmed using OASYS analysis of PEFs in the majority. Sixty percent of cases occurred in healthcare, education and government sectors. The most frequently implicated causative exposures or agents were: indoor air (9), printing, copying and laminating (7), cleaning chemicals (4), mould and damp (4), and acrylic flooring and adhesives (4). Exposures were grouped into internal office environment, office ventilation-related and adjacent environment. CONCLUSIONS: Clinicians should be vigilant for exposures associated with OA in office workers who present with work-related symptoms, where respiratory sensitizing agents may be present. A structured approach to assessment of the workplace is recommended.

Updated review of reported cases of reactive airways dysfunction syndrome.

BACKGROUND: A previous systematic review of the diagnosis of reactive airways dysfunction syndrome (RADS), undertaken from 1985 to 2004, found a lack of standardization of case reporting, thus misattribution of symptoms can occur. AIMS: We aimed to update the systematic review, update the list of reported causes and see whether a more structured approach to reporting has been adopted. METHODS: We undertook a systematic literature review, using the databases EMBASE and Ovid MEDLINE, with search terms 'reactive airways dysfunction syndrome' or 'asthma AND acute irritant', and reported according to PRISMA guidelines. We included papers and abstracts published from January 2005 to September 2019, and articles were grouped by the presence or absence of diagnostic features: 'definite' RADS (met Brooks' criteria) or 'possible' RADS (Brooks' criteria not met or insufficient data). We collected demographic and diagnostic data for cases, where given. RESULTS: Eleven papers and six conference abstracts met the inclusion criteria, 13 of which were case series or reports, and comprised 752 cases in total; seven articles met Brooks' criteria for RADS diagnosis. A variety of agents were implicated, with chlorine or chlorine-releasing molecules most frequently reported. CONCLUSIONS: A lack of standardized reporting of RADS remains. The majority of published articles and conference abstracts either do not meet, or contain insufficient data to judge against, Brooks' criteria, particularly in relation to onset of symptoms and bronchial hyper-reactivity or variability of airflow obstruction. Some novel agents are described, in keeping with recognized structural taxonomies.

Evaluation of visceral larva migrans by radioimmunoassay systems.

A 9-year-old child with miliary pulmonary infiltrates, eosinophilia, and hyperimmunoglobulinemia E recovered rapidly cover a four-week period. Subsequent analysis of serum samples by a solid phase radioimmunoassay technique demonstrated IgM, IgE, and IgG antibodies to Ascaris suum antigen which declined following the acute phase of the illness in parallel with a decline in serum IgM, IgE, and IgG concentrations. Precipitating antibodies in serum against Ascaris antigen were demonstrated. The diagnosis is considered to be toxocariasis or ascariasis. The application of sensitive radioimmunoassay techniques of this type should provide a method of earlier diagnosis and the demonstration of rapidly changing antibody levels a method of confirming the diagnosis in parasitic diseases.

ABO hemolytic disease in Puerto Rico and North Carolina.

A prospective study was carried out at the University of Puerto Rico Hospital (UPRH) and at the North Carolina Baptist Hospital (NCBH) in order to establish the incidence of ABO hemolytic disease (ABO HD) in the two populations and to determine the relationship of intestinal parasitic infection of the mother to ABO HD in the infant. The incidence of ABO HD among UPRH at risk pregnancies (type O mother with type A or B infant) was 28.3% or 1 in 3.5 as compared with 18.4% or 1 in 5.4 of NCBH at risk pregnancies (P less than .05). Indirect Coombs' tests in cord sera, representing the passive transfer from mother to fetus of antibodies directed toward antigens on the infants' erythrocytes, were positive in 58.8% of UPRH at risk infants as opposed to 40.4% of NCBH at risk infants (P less than .001). Maternal isohemagglutinin titers at term were higher in type O UPRH mothers than in type O NCBH mothers (P less than .01). A relationship between helminth parasitic infection of the mother and ABO HD in the infant was suspected but not proved.

Histochemical diagnosis of Hirschsprung disease.

A histochemical staining technique for detection of acetylcholinesterase (AChE) in rectal suction biopsies was compared with the presence or absence of ganglion cells in full-thickness or suction biopsies for the diagnosis of Hirschsprung disease (HD) in infants and children. Biopsies from 55 of 58 children were adequate for both the AChE assay and routine pathologic examination for ganglion cells. Two patterns of AChE staining were noted. With pattern A, prominent nerve fibers staining for AChE were seen throughout the muscularis mucosa and the lamina propria. With pattern B, similar fibers were seen only in the muscularis mucosa and the areas of lamina propria that were immediately adjacent. No "false-negative" AChE staining reactions were found in patients with HD. No "false-positive" reactions showing pattern A were found. This pattern was diagnostic for HD. Three false-positive reactions were found showing pattern B in patients with conditions other than HD. Among 22 patients with HD, 19 were males and three were females. Pattern A occurred in all age groups and in both sexes. Pattern B in patients with HD was seen exclusively in male infants 1 month of age or less. Experience suggests that the AChE staining of rectal suction biopsies is an excellent screening test for HD in infants and children. If pattern B is encountered, however, the specimen should be examined by routine pathologic techniques for the presence of submucosal ganglion cells.

Common replication strategies emerging from the study of diverse groups of positive-strand RNA viruses.

Studies using brome mosaic virus (BMV), Sindbis virus and poliovirus have provided evidence that disparate groups of plant and animal positive strand RNA viruses have remarkably similar replication strategies. The conservation of several functional domains within virus-encoded nonstructural proteins implies that, although the precise character of these and interacting host components varies for each virus, they employ similar mechanisms for RNA replication. For (+) strand replication, similarities in cis-acting sequence motifs and RNA secondary structures within 5' termini of genomic (+) strands have been identified and have been shown to participate in binding of host factors. The model presented for replication of BMV RNA suggests that binding of these factors to internal control region (ICR) sequence motifs in the double-stranded replication intermediate releases a single-stranded 3' terminus on the (-) strand that may be essential for initiation of genomic (+) strand synthesis. ICR sequences internal to the BMV genome were also found to be required for efficient replication. Asymmetric production of excess genomic (+) over (-) strand RNA, characteristic of all (+) strand viruses, may be accomplished through transition of the replicase from competence for (-) to (+) strand synthesis by the recruitment of additional host factors.

Visceral larva migrans: Immunoglobulins, precipitating antibodies and detection of IgG and IgM antibodies against Ascaris antigen.

Serum samples from ten children with visceral larva migrans were evaluated by analysis of: immunoglobulin concentrations, precipitin reactions against Toxocara and Ascaris antigens and blood group substances, and IgM and IgG activity against Ascaris antigen by radioimmunoassay (RIA). The elevated concentrations of serum IgE and IgG and the positive precipitin reactions which occurred in some cases are an aid in diagnosis but were not consistently present. Serum IgM concentrations were elevated in all cases. IgM or IgG antibodies against Ascaris suum antigen were detected in all cases by a solid phase RIA technique. Radioimmunoassay techniques of this type may provide a superior method of diagnosis, particularly if used with serial serum samples which demonstrate changing levels of antibodies.

Analysis of RNA stability and (-) strand content in viral infections using biotinylated RNA probes.

Non-radioactive biotinylated RNA probes specific for plus (+) and minus (-) sense RNAs of brome mosaic virus (BMV) were synthesized in vitro from a plasmid bearing a 200 base pair fragment complementary to the 3' terminus of each of the three genomic RNAs of the virus. Using virion RNAs isolated from BMV infected barley plants, the sensitivity of biotinylated RNAs as hybridization probes was compared with that of 32P-labeled probes in Northern hybridization assays. Although the sensitivity of biotinylated and 32P-labeled probes is similar (approximately 5 pg), the time required to detect the RNA bands was much less than for autoradiography; (-) sense RNAs could be detected in 30 min whereas 48 h or more were required by autoradiography. The value of biotinylated probes for following RNA stability was exemplified by the detection of supplied inocula in protoplasts 24 h post-inoculation. Quantitation of relative accumulation of progeny (+) and (-) sense RNAs by densitometry of the Northern blots probed with biotinylated RNAs paralleled that of radiolabeled probes. The application of these probes was extended to the detection of RNAs in barley protoplasts and BMV infected plant sap by dot hybridization. In these tests, viral RNAs were detected in as few as 250 protoplasts and sap dilutions up to 1:2000. The merits of these non-radioactive probes in monitoring the replication events by the detection and quantitation of mutant progeny RNAs of BMV are discussed.

Cell-mediated hypersensitivity to mite antigens in atopic dermatitis.

Cell-mediated hypersensitivity (CMH) to house dust mite antigens, as determined by increased DNA synthesis after coculture of mononuclear cells with Dermatophagoides farinae extract, was demonstrated in 11 of 16 children with atopic dermatitis (AD) as compared with two of 14 control subjects. Patient and control responses peaked at the same antigen dose (12.4 micrograms of mite protein per 10(5) cells). Patient responses were significantly greater at all mite protein concentrations. The increased DNA synthesis of stimulated cells was demonstrated to be a T-cell response in the one patient in whom T-cell-enriched cultures were studied. There was no relationship between CMH and lgE-mediated hypersensitivity to D farinae in the patient group. It is suggested that AD is associated with CMH reactions to allergens and that antigen competition may be involved in the reduced CMH responses to mitogens and antigens noted by other investigators.

Anhidrotic ectodermal dysplasia with transient hypogammaglobulinemia.

An 8-month-old white boy with anhidrotic ectodermal dysplasia (AED) who was referred to the North Carolina Baptist Hospital because of recurrent respiratory infections and hypogammaglobulinemia is presented. His mother had partial expression of AED suggesting x-linked recessive inheritance in this family. She was incidentally given oral glucocorticoids during pregnancy for the treatment of chronic urticaria. The patient's serum immunoglobulins G, A and M were low at 8 months but normal by 15 months of age, and immunologic evaluation failed to show a defect in antibody production or cell-mediated immunity. Although rare, the diagnosis of AED must be considered in infant boys with recurrent fever and respiratory infections. The diagnostic features of the disease may be subtle in young child prior to the eruption of the characteristic peg-shaped teeth.

Minus sense transcripts of brome mosaic virus RNA-3 intercistronic region interfere with viral replication.

Interference with virus replication through the use of defective viral sequences is providing new insight to replication strategies and novel approaches for induced resistance. Because replication of brome mosaic virus (BMV) is potentiated by the intercistronic region of RNA-3, we examined the effect of adding various (-)sense RNAs corresponding to this region in co-transfections with wild type BMV RNAs. Progeny accumulation in barley protoplasts transfected with RNAs 1+2 was decreased by 90% in the presence of (-)RNA-3 delta HindIII, the longest (-)sense transcript tested, and by 85% when RNA-3 was also present. This trans interference was concentration dependent, and the use of deletion derivatives of (-)RNA-3 delta HindIII revealed that previously identified regulatory sequences within the intercistronic region were responsible for the observed interference. These deletion mutants were found to be of differing stabilities and several served as effective substrates for host-encoded polymerase to yield complementary (+)strands. Indeed, it is possible that the copying of viral RNA by the host polymerase serves as a hybrid arrest mechanism for discriminating against viral RNA functions. However, neither the ability of these sequences to serve as templates for host polymerase nor their (+)strand products contributed to the interference phenomenon, which may provide a new approach for engineering resistance to viral infection.

Interference with brome mosaic virus replication by targeting the minus strand promoter.

Sense and antisense strategies for interfering with the replication of brome mosaic virus (BMV) were examined. The effects of 200 nucleotide-long sense and antisense transcripts, corresponding to the viral 3' end (-) strand promoter, on the accumulation of progeny viral RNAs were studied by co-inoculation with wildtype BMV RNAs. Progeny accumulation in barley protoplasts transfected with either sense or antisense transcripts of the (-) strand promoter and BMV RNAs-1 and -2 was decreased by more than 90%, and by 60 to 80% when RNA-3 was also present. This trans interference was concentration-dependent, and reduced both (+) and (-) strand progeny accumulation to a similar extent. The appearance of complementary (-) strands indicated that sense interfering transcripts could serve as templates for (-) strand synthesis, and the use of deletion mutants revealed that the observed interference was in part mediated by this template activity. The reproducibility of the protoplast assay used here allows rapid evaluation of interference strategies and comparisons to be made of alternative approaches to engineered resistance. The results presented here suggest that targeting viral (-) strand promoters with sense and antisense transcripts may be an effective method for engineering plant resistance to viral infection.

Phosphorylation of Sendai virus phosphoprotein by cellular protein kinase C zeta.

The phosphoproteins (P) of nonsegmented negative strand RNA viruses are viral RNA polymerase subunits involved in both transcription and replication during the virus life cycle. Phosphorylation of P proteins in several negative strand RNA viruses by specific cellular kinases was found to be required for P protein function. In the present study, using bacterially expressed unphosphorylated P protein of Sendai virus, a mouse parainfluenza virus, we have shown that the major cellular kinase that phosphorylates P protein in vitro is biochemically and immunologically indistinguishable from protein kinase C (PKC) zeta isoform. PKC zeta was packaged into the Sendai virion and remained associated with purified viral ribonucleoprotein, where it phosphorylated both the P and the nucleocapsid protein in vitro. When PKC zeta-specific inhibitory pseudosubstrate peptide was introduced into LLC-MK2 cells prior to Sendai virus infection, production of progeny virus was dramatically attenuated, and kinetic analysis revealed that primary transcription was repressed. These data indicate that phosphorylation of the Sendai virus P protein by PKC zeta plays a critical role in the virus life cycle.

Role of NH(2)- and COOH-terminal domains of the P protein of human parainfluenza virus type 3 in transcription and replication.

The phosphoproteins (P proteins) of paramyxoviruses play a central role in transcription and replication of the viruses by forming the RNA polymerase complex L-P and encapsidation complex (N-P) with nucleocapsid protein (N) and binding to N protein-encapsidated genome RNA template (N-RNA template). We have analyzed the human parainfluenza virus type 3 (HPIV3) P protein and deletion mutants thereof in an in vitro transcription and in vivo replication system. The in vitro system utilizes purified N-RNA template and cell extract containing L and P proteins coexpressed via plasmids using a recombinant vaccinia virus expression system. The in vivo system takes advantage of minigenome replication, which measures luciferase reporter gene expression from HPIV3 minigenomes by viral proteins in a recombinant vaccinia virus expression system. These studies revealed that the C-terminal 20-amino-acid region of P is absolutely required for transcription in vitro and luciferase expression in vivo, suggesting its critical role in viral RNA synthesis. The N-terminal 40-amino-acid region, on the other hand, is essential for luciferase expression but dispensable for transcription in vitro. Consistent with these findings, the C-terminal domain is required for binding of P protein to the N-RNA template involved in both transcription and replication, whereas the N-terminal domain is required for the formation of soluble N-P complex involved in encapsidation of nascent RNA chains during replication. Coimmunoprecipitation analysis showed that the P protein forms a stable homooligomer (perhaps a trimer) that is present in L-P and N-P complexes in the higher oligomeric forms (at least a pentamer). Interestingly, coexpression of a large excess of N- or C-terminally deleted P with wild-type P had no effect on minigenome replication in vivo, notwithstanding the formation of heterooligomeric complexes. These data indicate that P protein with a deleted terminal domain can function normally within the P heterooligomeric complex to carry out transcription and replication in vivo.

Regulation of (+):(-)-strand asymmetry in replication of brome mosaic virus RNA.

Transfection of barley protoplasts with brome mosaic virus (BMV) RNAs 1 + 2 in the absence of RNA-3 yielded a molar ratio for (+):(-)-strand progeny at 24 hr postinoculation near unity, whereas over 100-fold more (+)- than (-)-strand progeny accumulated in its presence. The presence of RNA-3 enhanced total (+)-strand RNA production 205-fold and that of RNAs 1 + 2 by 29-fold. In contrast, total (-)-strand RNA accumulation decreased by 68% and that for (-)RNAs 1 + 2 by 79% in the presence of RNA-3. Transfections containing an RNA-3 mutant (Gsgi----U RNA-3) that is incapable of yielding RNA-4 as a result of a single nucleotide substitution at the subgenomic RNA initiation site yielded only 66% of the (+):(-) asymmetry seen in the presence of wild-type RNA-3. Only 1.8-fold excess of (+)-over (-)-strand production was obtained for transfections that included delta SGP RNA-3, a deletion that includes the subgenomic promoter core and extends 43 nt into the RNA-4 sequence. Transfections containing RNA-3 mutants bearing frameshifts or deletions in the coat protein cistron yielded levels of asymmetry similar to those seen for Gsgi----U RNA-3. These findings implicate the subgenomic promoter and other sequences in the intercistronic region of RNA-3 as the primary determinants of asymmetric replication, although the coat protein may be an additional factor enhancing the accumulation of (+)-strand RNA.