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INTRODUCTION: A safety-conscious work environment allows high-reliability organizations to be proactive regarding safety and enables employees to feel free to report any concern without fear of retaliation. Currently, research on the antecedents to safety-conscious work environments is scarce. METHOD: Structural equation modeling was applied to test the mediating role of employee communication satisfaction in the relationship between constructive culture and a safety-conscious work environment in several nuclear power plants. RESULTS: Employee communication satisfaction partially mediated the positive relationships between a constructive culture and a safety-conscious work environment. CONCLUSIONS: Constructive cultures in which cooperation, supportive relationships, individual growth and high performance are encouraged facilitate the establishment of a safety-conscious work environment. This influence is partially explained by increased employee communication satisfaction. PRACTICAL APPLICATION: Constructive cultures should be encouraged within organizations. In addition, managers should promote communication policies and practices that support a safety-conscious work environment.

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OBJECTIVE: The human esophagus is regularly exposed to refluxed gastric acid. Therefore, its epithelial cells require for survival a means of extruding excess H+ from the cytoplasm. Because Na+/H+ exchange activity has been observed in many mammalian cell types, including that of rabbit esophagus, we sought its presence in human esophageal epithelium. METHODS: Human esophageal epithelial cells derived from endoscopic biopsy specimens or surgical esophagectomy specimens were grown in primary culture and loaded with the fluorescent dye, 2'7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, to monitor intracellular pH (pHi). RESULTS: Resting pHi in bicarbonate-free N'-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid was 7.5 +/- 0.03 (n = 50). Acidification using the NH4Cl prepulse technique lowered pHi by 0.6 +/- 0.02 pH units, with recovery ensuing at an initial rate of 0.09 +/- 0.04 pH units/min. Notably, the rate of recovery was faster the more acidic the pHi, and recovery was abolished by amiloride or replacement with an Na+-free buffer. Acidification by lowering pHo with HCl resulted in a similarly rapid rate of return as with the NH4Cl technique, and resting cells acidified by 0.17 +/- 0.02 pH units/5 min upon exposure to amiloride. CONCLUSIONS: Human esophageal cells possess an H+-extruding mechanism consistent with an Na+/H+ exchanger. This mechanism is active in resting cells, adapts to the degree of pHi lowering, and extrudes H+ efficiently whether loaded by intracellular or extracellular means, making it well suited for epithelial defense against acid injury.

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BACKGROUND & AIMS: In a prior study, esophageal epithelial cells within intact epithelium were observed to swell after exposure to low extracellular pH (pHo) caused by activation of a bumetanide-sensitive NaK2Cl cotransporter. Because these results were obtained by correlation of tissue wet-weight gain with morphological evidence of cell swelling, another method was selected to confirm and extend these findings. METHODS: Primary cultured rabbit esophageal cells were loaded with the fluorescent dye 2'-7'-bis(carboxyethyl)-5,6-carboxyfluorescein so that changes in intracellular pH (pHi) and cell volume could be simultaneously monitored by microfluorimetry. RESULTS: Cells exposed to low pHo in both bicarbonate-free and bicarbonate-containing buffers produced a decline in pHi to as low as 6.5, but this occurred without change in volume. However, when pHo was lowered to < or = 2, pHi declined to <6.5 and volume increased by 25% in 3 minutes. Removal of Na+, K+, or Cl- or adding bumetanide inhibited acid-induced swelling. Also, swelling was inhibited when cells were acidified in Ca2+-free media and eliminated by adding 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid to Ca2+-free media. CONCLUSIONS: Esophageal cells swell when low pHo reduces pHi to <6.5. At pHi <6.5, swelling occurs through excess osmolyte (and consequently water) uptake via a bumetanide-sensitive NaK2Cl cotransporter. Activation of this enzyme at low pHi seems to be mediated by increases in cell Ca2+.

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The purpose of the study was to investigate the effects of agmatine, an endogenous clonidine-displacing substance (CDS), on systemic hemodynamics in the anesthetized rat. Bolus intravenous (i.v.) injections of agmatine decreased systemic arterial pressure (SAP) and systemic vascular resistance in a dose-dependent manner. The development of acute tachyphylaxis to the systemic vasodepressor response to agmatine did not induce cross-tachyphylaxis to the systemic vasodepressor responses to bradykinin, isoproterenol and nitroglycerin. The present data demonstrate agmatine, as a CDS and agonist for imidazoline (I) receptors, possesses marked systemic vasodilator activity in the rat. The present data suggest that activation of I receptors may represent a novel mechanism of vasodilation in vivo.

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A specific and sensitive assay has been developed to quantitate triazolam in postmortem blood using 2H6-triazolam as an internal standard. Triazolam is isolated from whole blood by adsorption on an Amberlite XAD-2 resin and subsequent elution with an organic solvent. The extract is analyzed by gas chromatography/mass spectometry using selected ion monitoring (GC/MS/SIM) in the negative chemical ionization mode (Cl-). The procedure is presently being used in case work and the results from 36 cases are presented.

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