Longitudinal decline in pulmonary diffusing capacity among nitrate fertilizer workers.

BACKGROUND: This study is part of a 3-year follow-up of lung function among nitrate fertilizer production workers. AIMS: To study the possible adverse effects of occupational exposure to aerosols and gases on pulmonary diffusing capacity. METHODS: A longitudinal study of a cohort of fertilizer workers who performed single-breath carbon monoxide diffusing capacity (DLco) tests and spirometry in 2007 and 2010. The workers completed a questionnaire on respiratory symptoms and smoking habits. Exposure to mineral dust, acid aerosols and inorganic gases was measured. The overall median inhalable and thoracic aerosol mass concentrations were 1.1mg/m(3) (min-max: <0.93-45) and 0.21mg/m(3) (min-max: <0.085-11), respectively. RESULTS: There were 308 participants in 2007 with 168 returning subjects in 2010. Overall, we found a statistically significant decline in the DLco of 0.068 mmol/min/kPa/year, adjusted for gender, age, height, weight, smoking status and doctor-diagnosed asthma during the 3-year follow-up (P < 0.01). The change in DLco did not vary significantly between the various job groups. Subjects with respiratory symptoms did not show a larger decline in DLco than those without symptoms. CONCLUSIONS: This study indicates a larger than expected decline in the DLco of fertilizer workers during a 3-year follow-up. However, the decline was not related to specific exposures at work, or to possible covariates of exposure.

Clear cell differentiation in choroidal melanoma. COMS report no. 8. Collaborative Ocular Melanoma Study Group.

OBJECTIVE: To describe 2 enucleated eyes of patients enrolled in the Collaborative Ocular Melanoma Study that contained primary choroidal melanoma with clear cell features. METHODS: During a 9-year period, 1493 eyes enucleated as part of the Collaborative Ocular Melanoma Study routinely processed for histologic examination were evaluated by the pathology review committee (H.E.G, D.M.A, and W.R.G). Two eyes with unusual variants of choroidal melanoma were identified and immunostained for S100 protein and HMB 45. Portions of the tumors were processed for electron microscopic examination. RESULTS: Results of electron microscopic examination of both tumors displayed malignant melanoma (mixed cell type with many malignant cells with clear cytoplasm). The cytoplasm of the clear cells stained with periodic acid-Schiff and failed to stain when pretreated with diastase. Results of immunohistochemical stains in both tumors were positive for S100 protein and HMB 45 in the tumor cells. Results of electron microscopic examination showed that the cytoplasm of the clear cells contained scattered glycogen granules, premelanosomes, and melanosomes. CONCLUSION: These cases represent a clear cell variant of malignant melanoma of the choroid. This tumor should not be confused with metastatic clear cell carcinoma to the choroid.

Repression of histone gene transcription in quiescent 3T6 fibroblasts.

Maintaining murine 3T6 fibroblasts in serum-depleted medium for a period of three days results in a resting cell population that does not synthesize DNA. Histone mRNA levels, closely tied to the cell-proliferation rate, are low due to a reduced rate of synthesis. A comparison of histone gene transcription in vitro by nuclear extracts of quiescent or proliferative 3T6 cells showed that a 200-bp segment of the promoter was responsible for repressing gene activity when cells were in a G0 state. In the absence of the distal promoter region (-200 to -400), gene transcription remained high in quiescent cells, indicating the proximal promoter region (+1 to -200) was responsible for basal gene activity. Alterations in protein binding to the distal promoter region correlated with histone H4 gene activity, suggesting that repression of histone gene transcription is linked to the attachment of a specific nuclear protein. During G1, the histone H4 gene was efficiently transcribed in vitro, but an inability to process the histone pre-mRNA limited the cellular content of mature histone mRNA. This distinction between transcriptional (in G0) and post-transcriptional (in G1) mechanisms for modulating histone mRNA levels suggests that gene-regulatory factors are specifically activated in quiescent cells to reduce expression of non-essential genes.

Ocular findings in thoracic-pelvic-phalangeal dystrophy.

Two unrelated patients with thoracic-pelvic-phalangeal dystrophy syndrome had retinal degeneration. A pathologic study of both eyes from one of the patients showed severe degeneration of the peripheral retina, with predominantly cone-type cells remaining.

Vitreous findings in fellow eyes of aphakic retinal detachment.

One hundred patients had bilateral aphakia, primary rhegmatogenous retinal detachment, and adequate visualization of the retinal and vitreous in the fellow eye. Of 43 patients with posterior vitreous separation and no retinal tear in the fellow eye, only one (2%) subsequently developed retinal detachment. Of 40 patients without posterior vitreous separation in the fellow eye, eight (20%) later developed retinal detachment following posterior vitreous separation. The remaining 17 patients had posterior vitreous separation and retinal tear or detachment at the time of initial examination. Thus, if posterior vitreous separation occurs without forming retinal tear, the risk of developing retinal detachment is significantly lowered.