Health survey of employees regularly using 3D printers.

Background: 3D printers emit potentially hazardous ultrafine particles and volatile organic compounds. Workers using 3D printing technologies may be at risk of respiratory illness from occupational exposure. Aims: To assess whether 3D printing is associated with health effects in occupational users. Methods: This was a preliminary survey. Workers in 17 companies using 3D printing, including commercial prototyping businesses, educational institutions and public libraries, in the Greater Toronto Area, Canada, were asked to complete survey questionnaires concerning demographic, occupational and health information. Associations between self-reported health history variables and occupational characteristics were examined by chi-square and Fisher's exact tests. Results: Among 46 surveyed workers, 27 (59% of participants) reported having respiratory symptoms at least once per week in the past year. Working more than 40 h per week with 3D printers was significantly associated with having been given a respiratory-related diagnosis (asthma or allergic rhinitis) (P < 0.05). We observed a wide variation in occupational hygiene practices in the 17 printing workplaces that we surveyed. Conclusions: Our finding of frequently reported respiratory symptoms suggests a need for additional studies on exposed workers in this field.

Case report of asthma associated with 3D printing.

BACKGROUND: Three-dimensional (3D) printing is being increasingly used in manufacturing and by small business entrepreneurs and home hobbyists. Exposure to airborne emissions during 3D printing raises the issue of whether there may be adverse health effects associated with these emissions. AIMS: We present a case of a worker who developed asthma while using 3D printers, which illustrates that respiratory problems may be associated with 3D printer emissions. CASE REPORT: The patient was a 28-year-old self-employed businessman with a past history of asthma in childhood, which had resolved completely by the age of eight. He started using 10 fused deposition modelling 3D printers with acrylonitrile-butadiene-styrene filaments in a small work area of approximately 3000 cubic feet. Ten days later, he began to experience recurrent chest tightness, shortness of breath and coughing at work. After 3 months, his work environment was modified by reducing the number of printers, changing to polylactic acid filaments and using an air purifier with an high-efficiency particulate air filter and organic cartridge. His symptoms improved gradually, although he still needed periodic treatment with a salbutamol inhaler. While still symptomatic, a methacholine challenge indicated a provocation concentration causing a 20% fall in FEV1 (PC20) of 4 mg/ml, consistent with mild asthma. Eventually, his symptoms resolved completely and a second methacholine challenge after symptom resolution was normal (PC20 > 16 mg/ml). CONCLUSIONS: This case indicates that workers may develop respiratory problems, including asthma when using 3D printers. Further investigation of the specific airborne emissions and health problems from 3D printing is warranted.

Molecular basis of cooperative DNA bending and oriented heterodimer binding in the NFAT1-Fos-Jun-ARRE2 complex.

Cooperative DNA binding by transcription factors that bind to separate recognition sites is likely to require bending of intervening sequences and the appropriate orientation of transcription factor binding. We investigated DNA bending in complexes formed by the basic region-leucine zipper domains of Fos and Jun with the DNA binding region of nuclear factor of activated T cells 1 (NFAT1) at composite regulatory elements using gel electrophoretic phasing analysis. The NFAT1-Fos-Jun complex induced a bend at the ARRE2 site that was distinct from the sum of the bends induced by NFAT1 and Fos-Jun separately. We designate this difference DNA bending cooperativity. The bending cooperativity was directed toward the interaction interface between Fos-Jun and NFAT1. We also examined the influence of NFAT1 on the orientation of Fos-Jun heterodimer binding using a novel fluorescence resonance energy transfer assay. The interaction with NFAT1 could reverse the orientation of Fos-Jun heterodimer binding to the ARRE2 site. The principal determinants of both cooperative DNA bending and oriented heterodimer binding were localized to three amino acid residues at the amino-terminal ends of the leucine zippers of Fos and Jun. Consequently, interactions between transcription factors can remodel promoters by altering DNA bending and the orientation of heterodimer binding.

DNA bending by Fos-Jun and the orientation of heterodimer binding depend on the sequence of the AP-1 site.

Interactions among transcription factors that bind to separate promoter elements depend on distortion of DNA structure and the appropriate orientation of transcription factor binding to allow juxtaposition of complementary structural motifs. We show that Fos and Jun induce distinct DNA bends at different binding sites, and that heterodimers bind to AP-1 sites in a preferred orientation. Sequences on each side of the consensus AP-1 recognition element have independent effects on DNA bending. A single base pair substitution outside the sequences contacted in the X-ray crystal structure alters DNA bending. Substitution of sequences flanking the AP-1 site has converse effects on DNA bending in opposite directions, suggesting that the extent of DNA bending by Fos and Jun is determined in part by the anisotropic bendability of sequences flanking the AP-1 site. DNA bending by Fos and Jun, and the orientation of heterodimer binding are interrelated. Reversal of the orientation of heterodimer binding causes a shift in the direction of DNA bending. The preferred orientation of heterodimer binding is determined both by contacts between a conserved arginine in the basic region of Fos and the central asymmetric guanine as well as the structure of sequences flanking the AP-1 site. Consequently, the structural adaptability of the Fos-Jun-AP1 complex may contribute to its functional versatility at different promoters.

Structural basis of DNA bending and oriented heterodimer binding by the basic leucine zipper domains of Fos and Jun.

Interactions among transcription factors that bind to separate sequence elements require bending of the intervening DNA and juxtaposition of interacting molecular surfaces in an appropriate orientation. Here, we examine the effects of single amino acid substitutions adjacent to the basic regions of Fos and Jun as well as changes in sequences flanking the AP-1 site on DNA bending. Substitution of charged amino acid residues at positions adjacent to the basic DNA-binding domains of Fos and Jun altered DNA bending. The change in DNA bending was directly proportional to the change in net charge for all heterodimeric combinations between these proteins. Fos and Jun induced distinct DNA bends at different binding sites. Exchange of a single base pair outside of the region contacted in the x-ray crystal structure altered DNA bending. Substitution of base pairs flanking the AP-1 site had converse effects on the opposite directions of DNA bending induced by homodimers and heterodimers. These results suggest that Fos and Jun induce DNA bending in part through electrostatic interactions between amino acid residues adjacent to the basic region and base pairs flanking the AP-1 site. DNA bending by Fos and Jun at inverted binding sites indicated that heterodimers bind to the AP-1 site in a preferred orientation. Mutation of a conserved arginine within the basic regions of Fos and transversion of the central C:G base pair in the AP-1 site to G:C had complementary effects on the orientation of heterodimer binding and DNA bending. The conformational variability of the Fos-Jun-AP-1 complex may contribute to its functional versatility at different promoters.

A monovalent C mu 4-specific ligand enhances the activation of human B cells by membrane IgM cross-linking ligands.

The ligand-receptor binding requirements for achieving full B cell activation through the membrane immunoglobulin (mIg) signaling pathway are relatively demanding, and mIg-antigen engagements which fall below these critical thresholds cause, at most, only the partial activation of B cells. In an effort to resolve new means of enhancing the efficacy of mIgM-mediated signal transduction, as well as to further understand the process by which mIgM-mediated signals are initiated, we have explored the mechanism for a previously reported synergy between certain mixtures of murine anti-IgM mAbs in eliciting human B cell DNA synthesis. We here report that striking synergy occurs when any of several relatively high affinity mAbs specific for diverse domains of mIgM are combined in culture with the relatively low affinity C mu 4-specific ligand, mAb IG6. Although B cell activation was dependent upon the bivalency, and hence mIgM cross-linking potential, of the high affinity ligand, low affinity mAb IG6 could enhance the activation process when present as a monovalent Fab' fragment. This did not appear due to F(ab')2 contamination or Fab' aggregation, since IG6 Fab' preparations were notably compromised in several other functions requiring ligand bivalency. Pulsing studies revealed that the C mu 4-specific ligand exhibits its functional effects only when stimulatory mIgM receptor cross-links are being formed by bivalent ligands, and that IG6 Fab' enhancement is most notable during the later interval of the prolonged mIgM signaling process that leads to S phase entry. A unique region of the membrane-proximal IgM domain may be important for Fab'-mediated enhancement, since Fab' fragments that bind with higher affinities to distinct sites on C mu 4 were not as effective at mediating this phenomenon. Several possibilities for the adjuvant effects of this C mu 4-specific Fab' on B cell responses triggered by mIgM crosslinking ligands are discussed, including the possibility that IG6 Fab' influences the potential for mIgM dimer formation or interactions of mIgM with other signal-transducing molecules.

T cell responses in Hodgkin's disease: frequency distribution of IL-2 producing cells and quantitation of IL-2 produced per cell.

T cell dysfunction in Hodgkin's disease (HD) is well documented. Since interleukin-2 (IL-2) plays a pivotal role in T cell proliferation, we have investigated frequency distribution of IL-2 producing phytohaemagglutinin (PHA)-stimulated lymphocytes from HD patients compared to that of healthy donors using two limiting dilution (LD) culture systems in which autologous peripheral blood lymphocytes (PBL) and Epstein Barr Virus transformed allogeneic B lymphoblastoid cell lines (EBV-LCL) have been used as feeders. The latter provided better conditions for IL-2 production by single cells, as evident from the enhanced frequencies obtained (For healthy donors: 1/67 +/- 1545.5 using EBV-LCL and 1/1123 +/- 1.7438 using autologous PBL as feeders). The data showed significantly reduced frequency of IL-2 producing cells as well as reduced quantity of IL-2 produced per cell in HD even after using/EBV-LCL as feeders, the amount of IL-2 produced per activated responder cell in HD patients being 0.825-1.3 pg/well (p < 0.001) as compared to 1.48-2.43 pg/well in healthy donors. Thus, the EBV-LCL feeders did provide better culture conditions for estimating frequencies of functional T cells. However these cell lines were unable to restore in vitro the abnormalities in functional properties of T cells in HD.

The chemical composition and nutritional potential of the tribal pulse, Abrus precatorius L.

The boiled seeds of Abrus precatorius L. are eaten by the residents of the Andaman Islands in India. The seeds were analysed for proximate composition, total (true) protein, seed protein fractions, amino acid profile of seed proteins, minerals and certain antinutritional factors. The seed proteins are rich in most of the essential amino acids, and they are deficient only in cystine and threonine, when compared to the WHO/FAO requirement pattern. The antinutritional factors (total free phenols, tannins, trypsin inhibitor activity and haemagglutinating activity) were also investigated.

Nutritional and chemical evaluation of raw seeds of Canavalia gladiata (Jacq) DC. and C. ensiformis DC: the under utilized food and fodder crops in India.

In India, the seeds of Canavalia gladiata and C. ensiformis have traditionally been eaten by the aborigines, but they are less popular among the civilized people. The data on the chemical composition and nutritional quality of these seeds are not readily available. The proximate composition, mineral composition, the contents of total (true) proteins, seed protein fractions, profile of seed protein amino acids and certain antinutritional factors were analysed and reported in the present study. The seeds of C. ensiformis contain more crude protein, crude lipid and minerals like Na, K, Ca, Mg, P, Fe and Mn than does C. gladiata. Both albumins and globulins together constitute the major bulk of seed proteins. In both the species of Canavalia investigated, glutamic acid, aspartic acid, isoleucine + leucine, tyrosine + phenylalanine and lysine are the major amino acids of seed proteins. The presence of certain antinutritional factors (total free phenols, tannins, lectins, L-DOPA, trypsin inhibitor activity) is also reported for both species of Canavalia.

The biochemical composition and nutritional potential of the tribal pulse, Mucuna gigantea (Willd) DC.

Seeds of the tribal pulse, Mucuna gigantea, were analysed for proximate composition, total (true) seed proteins, seed protein fractionation, amino acid composition, minerals and antinutritional factors. Crude proteins, crude lipids, ash and nitrogen free extractives constituted 30.62%, 9.03%, 5.99% and 42.79%, respectively. The calorific values of 100 g dry matter of seed material is 374.91 kCal. The essential amino acids, leucine + isoleucine, are present in relatively large quantities. The seeds are rich in minerals like K, Ca, Mg and Fe. Antinutritional substances like total free phenols and tannins, trypsin inhibitor activity and haemagglutinating activity also were investigated.

Natural killer and lymphokine activated killer cell functions in Hodgkin's disease.

We report the natural killer (NK) and lymphokine activated killer (LAK) cell activities in peripheral blood lymphocytes (PBL) from untreated patients with Hodgkin's disease (HD) and from healthy donors. The frequency of LAK cell precursors was also studied using limiting dilution analysis (LDA). About 75% of the HD patients had normal NK activity. There was a higher percentage of low NK responders (mean percent NK activity of healthy donors--2 SD) in patients with lymphocyte depletion histologic grade of the disease and those who were in clinical stage IV, suggesting a correlation of decrease in NK activity with poor prognosis. We found efficient LAK activity against the NK-sensitive K562 cells and NK-resistant VIP (melanoma) and T-24 (bladder carcinoma) tumour targets in both low and normal NK responder HD patients, irrespective of the histopathological grade and clinical stage of the disease. In concordance with their good LAK cell activity, HD patients showed a frequency distribution of LAK cell progenitors in the PBL comparable to that of healthy donors.

Establishment and characterization of four new squamous cell carcinoma cell lines derived from oral tumors.

Four cell lines were established from squamous cell carcinomas (SCC) of the oral cavity. Cell lines AW 13516 and AW 8507 were derived from poorly differentiated SCC and epidermoid carcinoma of the tongue respectively. Cell line AW 10498 was derived from moderately differentiated SCC of the lower alveolus, and AW 9803 grew from a well-differentiated SCC of a retromolar trigone. The cultures showed typical epithelial cell morphology, numerous mitotic figures, occasional multinucleated giant cells, individual cell diskeratosis and nuclear and nucleolar abnormalities. The cell lines AW 13516 and AW 8507 were fast growers with a doubling time of 35.5 h and 31.9 h, respectively, which was independent of the initial seeding density. Cell lines AW 10498 (doubling time 52.2 h) and AW 9803 (doubling time 66 h) showed slower growth and had shorter doubling times at higher seeding densities. The presence of cytokeratins was detected in all the four cell lines by using polyclonal antikeratin antisera in indirect immunofluorescence and in Western blotting. None of the cell lines expressed major histocompatibility complex (MHC) class II antigens. MHC class I antigens were expressed by three cell lines but not by AW 9803. Flow cytometric analysis of DNA content and chromosomal studies suggested the presence of polyploidy and aneuploidy in all the four cell lines. Ultrastructural studies revealed typical epithelial cell features, such as the presence of desmosomes, tonofilaments and keratin bundles.

Natural killer and lymphokine-activated killer cell functions in chronic myeloid leukemia.

The natural killer (NK) and lymphokine-activated killer (LAK) cell activities of peripheral blood lymphocytes from chronic myeloid leukemia (CML) patients in remission and from healthy donors have been studied. Regression analysis to compare both cytotoxic responses in individual donors and the frequency of LAK cell precursors was also carried out. About 42% of CML patients in remission showed low NK activity (less than the mean percentage NK activity of healthy donors--2 SD) and were categorised as low NK responders. The stage of remission or the drugs used to bring about remission did not influence the NK status. The LAK activity of low NK as well as normal NK responder CML patients was significantly low against the NK-sensitive K562 cell line and the NK-resistant VIP (melanoma) and T-24 (bladder carcinoma) tumor targets, as assessed by linear regression analysis. Allogeneic leukemic cells were more resistant to killing, especially by patients' LAK cells. The frequency analysis of LAK cell precursors revealed a significant reduction in the LAK cell progenitor frequency in CML patients in remission.

A sample survey of leprosy in the ELEP Leprosy Control Project, Dharmapuri, Tamil Nadu.

A sample survey of the Dharmapuri Leprosy Control Project was undertaken in 1983; a population of 60855 was enumerated out of which 51205 was examined. The sampling procedure which was followed consisted of stratifying the sub-centres according to prevalence and classifying the villages by the size of the population. Villages were selected by random allocation. 10 leprosy inspectors participated in the survey examining 626 to 774 persons per day. 859 active cases were detected giving a prevalence of 16.77 per thousand. The child prevalence was 6.19 per thousand. The number of lepromatous and BL cases detected were 70 giving an infectivity rate of 8.15%. The prevalence of leprosy as found in the last survey conducted in the different areas in the project approximate to those of the sample survey. Therefore it could be said that the prevalence has decreased in this project from 19.94 per thousand as observed in the first survey. The child prevalence has likewise decreased from 9.40 to 4.09 in the project.