Mineralogy of lung tissue in dental laboratory technicians' pneumoconiosis.

This article reports on a case of pneumoconiosis in a dental laboratory technician with a history of respiratory exposure to dental materials. Special attention is paid to the mineralogical analysis of the lung biopsy. The abundance of chromium, cobalt, and silica particles suggests that the dental technician's pneumoconiosis is the result of the combined effects of hard metal dusts and silica particles generated during finishing dental frameworks. Adequate technical protection such as a local ventilation system should be considered in dental laboratories to prevent respiratory exposure of dental technicians to airborne contaminants.     

Evaluation of occupational exposure to mixed dusts and polycyclic aromatic hydrocarbons in silicon carbide plants

Workers in the silicon carbide industry have experienced occupational health diseases, particularly lung disorders such as silicosis. The silicon carbide production process mainly employs petroleum coke, sawdust, pure crystalline silica and graphite. Since crystalline silica is present in the occupational environment, the airborne dust content of various polymorphs of silica, especially quartz, cristobalite and tridymite, was determined by X-ray diffraction analysis. The analytical method was modified to eliminate graphite, since it overlaps with the main diffraction plane of quartz. Exploratory field surveys were conducted to identify the minerals present in that occupational environment and to evaluate the validity of the analytical method. The surveys provided information on the mineralogical nature of the dust, its respirable content and the concentration of silica polymorphs. Polycyclic aromatic hydrocarbons also were measured, and the effect of their adsorption on graphite was evaluated.     

Chronic DMI reduces thresholds for brain stimulation reward in the rat

The authors sought a demonstration of the validity of brain stimulation reward (BSR) models of depression. It was predicted that chronic, but not acute antidepressant treatment would enhance BSR responding. Rats with medial forebrain bundle electrodes were separated into 4 groups that received either saline or desmethylimipramine at 5, 10, or 20 mg/kg daily. A rate-free, threshold measure that has not previously been employed in studies of BSR and antidepressants was used. BSR thresholds were monitored every 3rd day over a 9-day baseline period and an 18-day drug treatment period, and after 12 days of drug withdrawal. Groups did not differ from one another till the 15th and 18th day of drug treatment. The greatest effects were seen in the 10 and 20 mg groups. The 20 mg group returned to baseline after drug withdrawal, but the 10 mg group did not. The absolute size of the effect was considered to be small, leading the authors to speculate that antidepressants act on homeostatic mechanisms that stabilize BSR substrates, only indirectly enhancing transmission of the reward signal.     

Acid phosphatase activity in mononuclear phagocytes and the U937 cell line: monocyte-derived macrophages express tartrate-resistant acid phosphatase

Tartrate-resistant acid phosphatase (TRAcP) is used as a marker for osteoclasts, which are believed to be derived from phagocytic cells or phagocyte stem cell precursors. To further investigate the relationship between monocytic phagocytes and osteoclasts, acid phosphatase (AcP) activity was measured by three different techniques in human peripheral blood monocytes, monocyte-derived macrophages, and the U937 cell line. We found that cytochemistry and gel electrophoresis led to similar results, but that the colorimetric assay was inconsistent. Normal human peripheral monocytes expressed both tartrate-sensitive and -resistant AcP. In culture these cells formed polykaryons and expressed TRAcP activity that was further identified as an isoenzyme associated with bone tissue. In contrast, the U937 cells did not express TRAcP activity as measured by gel electrophoresis. Both U937 cells and monocytes possess material that interferes with interpretation of the colorimetric assay of AcP. The presence of TRAcP in monocyte-derived macrophages further supports the relationship between phagocytic cells and bone osteoclasts.     

Congenital abnormalities of the aortic arch: MR imaging

Thirty-four patients, 1 month to 63 years old, with known or suspected congenital abnormalities of the aortic arch underwent magnetic resonance (MR) imaging. Sixteen patients were studied retrospectively, 18 prospectively. In all retrospective studies, the aortic arch abnormality was seen with MR imaging. In the prospective studies, MR imaging enabled diagnosis in 15 of 18 (83%) patients. Twenty-nine of 34 patients underwent two-dimensional echocardiography; nine were studied retrospectively, 20 prospectively. In the prospective studies, echocardiography enabled diagnosis in 13 of 20 (65%) patients. Although two-dimensional echocardiography has a high sensitivity in the detection of aortic arch abnormalities in the neonate, arch abnormalities in the neonate, its sensitivity is lower in older children, adults, and postoperative patients. The authors' experience shows that MR imaging is an important, noninvasive modality in the evaluation of older children, adults, and postoperative patients with congenital aortic arch abnormalities.     

Pseudomalignancies

The plastic surgeon encounters a variety of lesions that are benign histologically, but malignant in terms of their manifestations and clinical course. Many of these desperate pathologic situations present exceedingly difficult problems in terms of their diagnosis and management. Clinical entities that tend to be grouped within this type of pathologic phenomenon include giant pigmented nevi, arteriovenolymphatic malformations, neurofibromatosis, and localized overgrowth. The authors examine such lesions on the basis of their presentations, pathogeneses, and pathophysiology.     

Detection of an asymptomatic gastroduodenal artery aneurysm by real-time and pulsed Doppler sonography

We describe an asymptomatic gastroduodenal artery aneurysm detected by real-time sonography. This lesion had the ultrasonographic characteristics of an aneurysm except for its unusual location and the absence of turbulent echogenic flow and pulsation. Pulsed-Doppler sonography confirmed the diagnosis by demonstrating bidirectional flow with systolic acceleration in the anechoic portion of the lesion.