Combined exposures to workplace psychosocial stressors: relationships with mental health in a sample of NZ cleaners and clerical workers.

BACKGROUND: A combined measure of two common psychosocial stressors, called job pressure has previously been shown to be strongly associated with poor mental health in high status workers. This study tests the generalizability of this association to lower status workers. METHODS: A national random sample of cleaners and clerical workers was obtained from the New Zealand (NZ) electoral roll by occupational title (n = 596). Cross-sectional data on job stressors, demographics, and mental health (GHQ-12) was collected by computer-assisted telephone interviews. RESULTS: Combined exposure to low job control, high job demands, and job insecurity (high job pressure) was associated with markedly elevated odds (13-fold or higher) of poor mental health after adjustment for age, sex, occupation, and education. CONCLUSION: Combined with previous findings this suggests simultaneous exposure to more than one occupational psychosocial stressor may greatly increase the risk of poor mental health among both lower and higher status workers. This report adds to the larger literature in this area, supporting the need for expanded policy and practice intervention to reduce job stressors across the working population.

Ascertainment of occupational histories in the working population: the occupational history calendar approach.

BACKGROUND: self-reported occupational histories are an important means for collecting historical data in epidemiological studies. An occupational history calendar (OHC) has been developed for use alongside a national occupational hazard surveillance tool. This study presents the systematic development of the OHC and compares work histories collected via this calendar to those collected via a traditional questionnaire. METHODS: the paper describes the systematic development of an OHC for use in the general working population. A comparison of data quality and recall was undertaken in 51 participants where both tools were administered. RESULTS: the OHC enhanced job recall compared with the traditional questionnaire. Good agreement in the data captured by both tools was observed, with the exception of hazard exposures. CONCLUSIONS: a calendar approach is suitable for collecting occupational histories from the general working population. Despite enhancing job recall the OHC approach has some shortcomings outweighing this advantage in large-scale population surveillance.

Prospective outcomes of injury study.

BACKGROUND: In New Zealand (NZ), 20% of adults report a disability, of which one-third is caused by injury. No prospective epidemiological studies of predictors of disability following all-cause injury among New Zealanders have been undertaken. Internationally, studies have focused on a limited range of predictors or specific injuries. Although these studies provide useful insights, applicability to NZ is limited given the importance of NZ's unique macro-social factors, such as NZ's no-fault accident compensation and rehabilitation scheme, the Accident Compensation Corporation (ACC). OBJECTIVES: (1) To quantitatively determine the injury, rehabilitation, personal, social and economic factors leading to disability outcomes following injury in NZ. (2) To qualitatively explore experiences and perceptions of injury-related outcomes in face-to-face interviews with 15 Maori and 15 other New Zealanders, 6 and 12 months after injury. SETTING: Four geographical regions within NZ. DESIGN: Prospective cohort study with telephone interviews 1, 4 and 12 months after injury. PARTICIPANTS: 2500 people (including 460 Maori), aged 18-64 years, randomly selected from ACC's entitlement claims register (people likely to be off work for at least 1 week or equivalent). DATA: Telephone interviews, electronic hospital and ACC injury data. Exposures include demographic, social, economic, work-related, health status, participation and/or environmental factors. OUTCOME MEASURES: Primary: disability (including WHODAS II) and health-related quality of life (including EQ-5D). Secondary: participation (paid and unpaid activities), life satisfaction and costs. ANALYSIS: Separate regression models will be developed for each of the outcomes. Repeated measures outcomes will be modelled using general estimating equation models and generalised linear mixed models.

The characteristics of rhizosphere microbes associated with plants in arsenic-contaminated soils from cattle dip sites.

Soil microorganisms and plants were studied in samples of arsenic-contaminated soil from two cattle dip sites. The aim was to delineate the parameters that will determine the feasibility of future remediation by growing arsenic-accumulating plants, including the identity and characteristics of some rhizosphere soil microbes. The soil samples contained high total, but low soluble arsenic concentrations which, together with other properties, resembled the previously reported characteristics of dip-site soils from this region of rural Australia. A glasshouse trial demonstrated that dip-site rhizosphere microbes promoted arsenic accumulation by the grass Agrostis tenuis on contaminated dip-site soil without inhibition of growth. The arsenic content of the shoots was increased by 45%. We studied the colonization of roots of dip-site plants by mycorrhizal fungi and tentatively identified six genera of other fungi present in the soil samples. Two plant species growing at the sites, Kikuyu grass (the most abundant plant) and Rainbow fern, exhibited mixed infections of their roots by endomycorrhizal fungi (tentatively identified as Acaulospora and Gigaspora) and by soil-born pathogens. Five rhizosphere bacteria were identified to genus level and we determined the effect of arsenic on their growth. The two most prevalent strains differed greatly in their growth sensitivity to arsenate; Arthrobacter sp. being the most sensitive while Ochrobactrum sp. exhibited exceptional resistance to arsenate. Of the other, less prevalent strains, two were Bacillus spp. and the last, Serratia sp., was the most resistant to arsenite. These findings show the importance of understanding plant-soil microbe interactions for developing future strategies aimed at a phytoremediation-based approach to removing arsenic from soil at dip sites.

The effect of growth hormone on the bursting strength of ileal anastomotic segments in radiation-injured rat bowel.

The potential for postoperative complications in irradiated intestinal anastomoses is well known. There has been limited evaluation of factors that may improve wound healing in radiation-injured bowel. Growth hormone (GH) has been shown to improve wound healing. In animal models GH has been demonstrated to increase strength of large bowel anastomoses in nonirradiated bowel. The purpose of this study was to evaluate, in a rat model, the effect of GH on the bursting pressure of radiation-injured terminal ileal anastomoses in a rat model. Fifty-four rats were treated with 1700 cGy of pelvic irradiation in a single dose. Seventeen weeks later resection of a segment of terminal ileum and an ileo-ileostomy was performed. Half the rats received GH (2.0 mg/kg/day) and the rest received normal saline subcutaneously for 7 days starting on the day of surgery. On the seventh postoperative day the anastomosis site was identified at reoperation and bursting pressure was measured in vivo. A significantly greater bursting pressure was observed in the GH-treated rats compared to the control group (208.9 +/- 27 cm H2O vs 177 +/- 53 cm H2O, P < 0.025). GH treatment resulted in an 18% greater strength of radiation-injured terminal ileal anastomotic segments, as measured by bursting pressure. These findings suggest a possible role for GH in decreasing the morbidity in patients who undergo intestinal surgery after radiation treatment.

ATP Hydrolysis Activity and Polymerization State of Ribulose-1,5-Bisphosphate Carboxylase Oxygenase Activase (Do the Effects of Mg2+, K+, and Activase Concentrations Indicate a Functional Similarity to Actin?).

The ATPase activity and fluoresence of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) activase were determined over a range of MgCl2, KCl, and activase concentrations. Both salts promoted ADP release from ATP and intrinsic fluorescence enhancement by adenosine 5[prime]-[[gamma]-thio] triphosphate, but Mg2+ was about 10 times more effective than K+. ATPase and fluorescence enhancement both increased from zero to saturation within the same Mg2+ and K+ concentration ranges. At saturating concentrations (5 mM Mg2+ and 22 mM K+), the specific activity of ATPase (turnover time, about 1 s) and specific intrinsic fluorescence enhancement were maximal and unaffected by activase concentration above 1 [mu]M activase; below 1 [mu]M activase, both decreased sharply. These responses are remarkably similar to the behavior of actin. Intrinsic fluorescence enhancement of Rubisco activase reflects the extent of polymerization, showing that the smaller oligomer or monomer present in low-salt and activase concentrations is inactive in ATP hydrolysis. However, quenching of 1-anilinonapthaline-8-sulfonate fluorescence revealed that ADP and adenosine 5[prime]-[[gamma]-thio] triphosphate bind equally well to activase at low- and high-salt concentrations. This is consistent with an actin-like mechanism requiring a dynamic equilibrium between monomer and oligomers for ATP hydrolysis. The specific activation rate of substrate-bound decarbamylated Rubisco decreased at activase concentrations below 1 [mu]M. This suggests that a large oligomeric form of activase, rather than a monomer, interacts with Rubisco when performing the release of bound ribulose-1,5-bisphosphate from the inactive enzyme.

Subsaturating Ribulose-1,5-Bisphosphate Concentration Promotes Inactivation of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase (Rubisco) (Studies Using Continuous Substrate Addition in the Presence and Absence of Rubisco Activase).

We developed a continuous-addition method for maintaining subsaturating concentrations of ribulose-1,5-bisphosphate (RuBP) for several minutes, while simultaneously monitoring its consumption by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This method enabled us to observe the effects of subsaturating RuBP and CO2 concentrations on the activity of Rubisco during much longer periods than previously studied. At saturating CO2, the activity of the enzyme declined faster when RuBP was maintained at concentrations near its Km value than when RuBP was saturating. At saturating RuBP, activity declined faster at limiting than at saturating CO2, in accordance with previous observations. The most rapid decline in activity occurred when both CO2 and RuBP concentrations were subsaturating. The activity loss was accompanied by decarbamylation of the enzyme, even though the enzyme was maintained at the same CO2 concentration before and after exposure to RuBP. Rubisco activase ameliorated the decline in activity at subsaturating CO2 and RuBP concentrations. The results are consistent with a proposed mechanism for regulating the carbamylation of Rubisco, which postulates that Rubisco activase counteracts Rubisco's unfavorable carbamylation equilibrium in the presence of RuBP by accelerating, in an ATP-dependent manner, the release of RuBP from its complex with uncarbamylated sites.

The source and characteristics of chemiluminescence associated with the oxygenase reaction catalyzed by Mn(2+)-ribulosebisphosphate carboxylase.

We confirm the observation of Mogel and McFadden (Mogel, S.N., and McFadden, B. A. (1990) Biochemistry 29, 8333-8337) that ribulosebisphosphate carboxylase/oxygenase (rubisco) exhibits chemiluminescence while catalyzing its oxygenase reaction in the presence of Mn2+. However, our results with the spinach and Rhodospirillum rubrum enzymes differ markedly in the following respects. 1) Chemiluminescence intensity was directly proportional to enzyme concentration and behaved as if representing the rate of oxygenase catalysis. 2) The wavelength spectrum peaked at about 770 nm and extended beyond 810 nm. This seems inconsistent with chemiluminescence generated by simultaneous decay of pairs of singlet O2 molecules. It is consistent with manganese(II) luminescence and we discuss its possible sources. The time course of chemiluminescence (resolution, 0.25 s) was distinctively different for spinach and R. rubrum enzymes during the initial 5 s of catalysis, with the bacterial enzyme exhibiting a pronounced initial "burst." Chemiluminescence by the spinach enzyme responded to substrate concentrations in a manner consistent with known oxygenase properties, exhibiting Michaelis-Menten kinetics with ribulose-1,5-bisphosphate (Km 400 nM). Chemiluminescence required carbamylated enzyme with Mn2+ bound at the active site (activation energy, -57.1 KJ.mol-1). As an indicator of oxygenase activity, chemiluminescence represents an improvement over oxygen electrode measurements in response time and sensitivity by factors of at least 100.

Understanding CLIA '88.

New regulations under the Clinical Laboratory Improvement Act of 1988 have been finalized, but not without objection from the State Society. This article outlines the regulations, compares them to those originally proposed in May 1990, presents a compliance timeline, and touches upon Society concerns.

Activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) by rubisco activase : effects of some sugar phosphates.

The activation of purified ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) has been studied in the presence of sugar phosphates, and the effect of rubisco activase on this process determined. During an 11-minute time course at pH 7.7 and 11 micromolar CO(2), the activation of rubisco was strongly inhibited by ribulose-1,5-bisphosphate (4 millimolar), fructose-1,6-bisphosphate (1 millimolar) and ribose 5-phosphate (5 millimolar), but this inhibition was overcome by the addition of rubisco activase and activation then proceeded to a greater extent than spontaneous activation of rubisco. Glycerate 3-phosphate (20 millomolar) slowed the initial rate but not the extent of activation and rubisco activase had no effect on this. The activation of rubisco was shown to be affected by phosphoenolpyruvate (3 millimolar) but not by creatine phosphate (3 millimolar) or ATP (3 millimolar), and the creatine-phosphate/creatine phosphokinase system was used to generate the high ATP/ADP quotients required for rubisco activase to function. ATP was shown to be required for the rubisco activase-dependent rubisco activation in the presence of fructose-1,6-bisphosphate (1 millimolar). It is concluded that rubisco activase has a mixed specificity for some sugar phosphate-bound forms of rubisco, but has low or no activity with others. Some possible bases for these differences among sugar phosphates are discussed but remain to be established.

A short N-proximal region of prochymosin inhibits the secretion of hybrid proteins from Escherichia coli.

A gene encoding bovine prochymosin (PC) was fused to the coding sequence (phoA) for the Escherichia coli alkaline phosphatase (AP) signal peptide and expressed in E. coli under the control of the phoA promoter. Upon induction, an AP-PC fusion protein was produced which was neither processed nor exported into the periplasm. We investigated this lack of secretion by constructing a series of gene fusions in which different regions of the PC gene were inserted between the coding regions of the AP leader and mature protein. Analysis of the cellular location of the proteins encoded by these fusions revealed that a region of PC (between amino acids 6 and 29) prevented processing and secretion of an AP-PC fusion when inserted near to the AP signal peptide. In contrast, when this 'blocking sequence' was inserted elsewhere in AP the hybrid proteins were efficiently processed and translocation was initiated.