Ocular effects of exposure to triethylamine in the sand core cold box of a foundry

OBJECTIVES

To assess the acute and chronic ophthalmological effects of triethylamine exposure among foundry workers.

METHODS

Ocular effects on people currently, previously, and never exposed to triethylamine in a foundry cold box were studied at two points in time. The initial phase included an ocular examination with a slit lamp to assess corneal health, a visual acuity test, and a questionnaire to assess vision symptoms. The follow up included measurements of corneal thickness with an ultrasonic pachymeter and the vision symptoms questionnaire before and after the shift and at the beginning and end of the week. Personal air measurements for triethylamine were also obtained during the follow up.

RESULTS

The vision symptoms of blurriness, halos around lights, and blue hazy vision occurred more often in currently exposed workers than those previously or never exposed to triethylamine. Air concentrations of triethylamine ranged from < 0.33 mg/m3 to 20.3 mg/m3. Among currently exposed workers, symptoms were more common among those with exposure to > 10 mg/m3 of triethylamine (odds ratio (OR) = 3.0, 95% confidence interval (95% CI) 0.35-25.6). No differences in corneal thickness were found in currently or previously exposed workers and those never exposed. No increase in corneal thickness was found after v before the shift.

CONCLUSION

Despite low concentrations of triethylamine and no corneal oedema, workers exposed to triethylamine reported vision symptoms. Possible explanations for these symptoms without corneal oedema are that triethylamine affects ciliary muscle function or that the corneal oedema was transient and not present when corneal thickness measurements were taken. No chronic effects were found in previously exposed workers. Further research is needed to elucidate the mechanism for the reported vision symptoms, which occurred below the current United States eight hour time weighted standard of 100 mg/m3 and the American Conference of Governmental Industrial Hygienists (ACGIH) recommended value at the time of our study of 40 mg/m3. We recommend that air concentrations be maintained to meet the current recommended ACGIH threshold of 4.1 mg/m3.

Ultrastructural studies bearing on the mechanism of UVB-impaired induction of contact hypersensitivity to DNCB in man

In both murine and human experimental systems, acute, low dose exposure of skin to ultraviolet B light (UVB) impairs the induction of allergic contact dermatitis (ACD) by haptens such as dinitrochlorobenzene (DNCB) in a significant proportion of individuals. By light microscopy, epidermal Langerhans cells (LC) have been reported to be depleted by UVB exposure as well as by epicutaneous hapten application, implying that LC may be the locus of action of the effects of both UVB and DNCB. However, light microscopy can not readily distinguish cell density changes secondary to LC necrosis from changes resulting from down-modulation of expression of LC surface molecules. Using a highly sensitive immunogold electron microscopic approach, we have evaluated the differential effects of UVB and/or DNCB on human epidermal LC. The results reveal that DNCB alone caused significant up-regulation of cell surface HLA class II expression on a very small number of LC, the major fraction of LC expressing normal levels of HLA class II. Furthermore, DNCB alone caused a modest reduction in the density of LC at the treated sites without evidence of cell necrosis. Treatment with UVB alone or UVB exposure followed by DNCB resulted in a reduction in the density of LC, with widespread evidence of LC necrosis. However, the few remaining intact LC were all intensely HLA class II-positive after UVB exposure followed by DNCB, whereas treatment with UVB alone did not result in changes in LC HLA class II expression. The findings that after DNCB painting only a small proportion of the LC were strongly HLA class II-positive, but after UVB exposure followed by DNCB all intact LC displayed significant up-regulation of cell surface HLA class II expression, imply that UVB exposure inhibits the migration of epidermal LC. This is consistent with the view that DNCB fails to induce ACD when hapten is painted on UVB-exposed skin because insufficient LC are available to initiate T cell activation in the draining lymph node.

Tree-structured vector quantization of CT chest scans: image quality and diagnostic accuracy

The authors apply a lossy compression algorithm to medical images, and quantify the quality of the images by the diagnostic performance of radiologists, as well as by traditional signal-to-noise ratios and subjective ratings. The authors' study is unlike previous studies of the effects of lossy compression in that they consider nonbinary detection tasks, simulate actual diagnostic practice instead of using paired tests or confidence rankings, use statistical methods that are more appropriate for nonbinary clinical data than are the popular receiver operating characteristic curves, and use low-complexity predictive tree-structured vector quantization for compression rather than DCT-based transform codes combined with entropy coding. The authors' diagnostic tasks are the identification of nodules (tumors) in the lungs and lymphadenopathy in the mediastinum from computerized tomography (CT) chest scans. Radiologists read both uncompressed and lossy compressed versions of images. For the image modality, compression algorithm, and diagnostic tasks the authors consider, the original 12 bit per pixel (bpp) CT image can be compressed to between 1 bpp and 2 bpp with no significant changes in diagnostic accuracy. The techniques presented here for evaluating image quality do not depend on the specific compression algorithm and are useful new methods for evaluating the benefits of any lossy image processing technique.

Analysis of effects of ultraviolet B radiation on induction of primary allergic reactions

Acute, low-dose exposure to UVB light reveals a genetic polymorphism in humans with respect to the ability of irradiated skin to support the induction of contact hypersensitivity (CH) to dinitrochlorobenzene (DNCB). In healthy adult caucasians, as well as in humans with deeply pigmented skin, approximately 45% fail to develop CH when DNCB is painted on UVB-irradiated skin; these individuals are termed "UVB susceptible" (UVB-S), whereas those who develop CH at the challenge site are termed "UVB resistant" (UVB-R). The UVB-S trait is characteristic of virtually all patients with biopsy-proved basal/squamous cell cancer, and may therefore be a risk factor for this disease. We have investigated the effects of UVB on expression of primary allergic reactions (PAR) in healthy caucasian and black-skinned adults, as well as patients with skin cancer. Among UVB-R caucasians, very few (less than 25%) developed PAR at site exposed to UVB, whereas among black-skinned UVB-R subjects, all displayed a PAR at the UVB irradiated site. To determine whether the lack of PAR in UVB-R caucasian subjects was systemic or local in origin, DNCB was applied to UVB-exposed buttock skin, and each individual was then challenged with dilute DNCB on forearm skin twice: 11 and 30 d thereafter. When inflammatory responses were evaluated at the original hapten application site, as well as both challenge sites, complete concordance was observed between positive challenge reactions at 30 d (UVB-R) and positive challenge reactions at 11 d, whereas only one caucasian subject displayed a PAR at 12 d. Thus, UVB-R caucasians can display CH as early as 11 d following hapten application to UVB-treated skin, indicating that their failure to display PAR is a local, rather than a systemic, effect of UVB. Because UVB-induced phototoxicity was significantly greater in caucasian than in deeply pigmented skin, it is anticipated that phototoxicity leads to rapid hapten "washout" from UVB-exposed caucasian skin. We propose that PAR usually do not occur in UVB-treated caucasian skin because insufficient hapten remains at the site to trigger a spontaneous inflammation when systemic hapten-specific immunity emerges.

Endoscopic band ligation for treatment of non-variceal upper gastrointestinal bleeding

An endoscopic band ligation method was successful in achieving hemostasis in two patients who had severe coagulopathy and profuse gastrointestinal bleeding from a visible vessel in the stomach. Bleeding was not controlled by multiple epinephrine injections or BICAP electrocoagulation. The technique of band ligation was easy to perform and may provide an alternative treatment for non-variceal upper gastrointestinal bleeding in selected cases.

Short-term release cues to stop-consonant place of articulation in child speech

In recent work Blumstein and Stevens (J. Acoust. Soc. Am. 66, 1001-1017 (19179); 67, 648-662 (1980) have proposed that the short-term onset spectra at stop-consonant releases provide invariant cues for the perception of place of articulation, and that the salient acoustic characteristics of these cues can be characterized by a set of templates. The present study investigated the suitability of these templates for characterizing place of articulation in utterance-initial voiced stop consonants produced by two children 71-75 weeks old in spontaneous discourse. The overall correct categorization rate for the templates was 65%, with 70% correct categorizations for the bilabial template, 85% for the alveolar template, and 40% for the velar template. The results of a perceptual study in which listeners were asked to identify place of articulation for computer-edited 15-, 25-, 40-, and 135-ms samples of the initial parts of these utterances were compared with the results of the template matching study. Although listeners' identification of place of articulation was at well above chance level on even the 15-ms tokens, there was no correlation between the results of the template-matching study and the perceptual data. The perceptual data thus indicate that short-term onset cues exist in the spontaneous speech of children at an early stage of language development, however, these cues do not appear to be adequately characterized by the Blumstein-Stevens templates.

Parathyroid autotransplantation in renal osteodystrophy

Severe renal osteodystrophy with metaphyseal fractures developed in two children with hypoplastic-dysplastic kidneys and chronic renal failure despite therapy with vitamin D, CaCO3, phosphate-binding agents, and protein restriction. Serum immunoreactive parathyroid hormone (iPTH) levels were elevated to 709 and 1,537 pg/mL (N = 255 +/- 92 pg/mL). Total parathyroidectomy and then autotransplantation of a small portion of parathyroids into the left brachioradialis muscle resulted in complete healing of renal osteodystrophy with the same dose of vitamin D. Serum iPTH and histological studies have demonstrated functioning parathyroid autotransplants, 19 and 20 months postoperatively in these two patients. Advantage of such a procedure over 3 3/4 parathyroidectomy is that this transplanted parathyroid tissue is easily accessible for partial removal in case of recurrence of uncontrollable hyperparathyroidism. We believe that total parathyroidectomy and autotransplantation can be successfully performed even in small children.