Colocalization of apolipoprotein AI in various kinds of systemic amyloidosis.

Apolipoprotein AI (apoAI), a major component of high-density lipoproteins, is one of the major amyloid fibril proteins and a minor constituent of the senile plaques observed in Alzheimer's disease. We examined colocalization of apoAI in various kinds of systemic amyloidosis in this study. Forty-three of 48 formalin-fixed paraffin-embedded heart specimens with various forms of systemic amyloidosis reacted immunohistochemically with anti-human apoAI antibody. ApoAI was also detected in water-extracted amyloid material by immunoblotting. In addition, we observed colocalization of apoAI and murine amyloid A (AA) amyloidosis in human apoAI transgenic mice. This is the first report of colocalization of apoAI with amyloid deposits in various forms of human systemic amyloidosis and murine AA amyloidosis in human apoAI transgenic mice. ApoAI may not always be a major component of amyloid fibrils, even when it is present in systemic amyloid deposits.     

Overtime Work and Prevalence of Diabetes in Japanese Employees: Japan Epidemiology Collaboration on Occupational Health Study

Objective

Epidemiologic evidence on long working hour and diabetes has been conflicting. We examined the association between overtime work and prevalence of diabetes among Japanese workers.

Methods

The subjects were 40,861 employees (35,170 men and 5,691 women), aged 16 to 83 years, of 4 companies in Japan. Hours of overtime were assessed using self-reported questionnaires. Diabetes was defined as a fasting plasma glucose ≥126 mg/dl (7.0 mmol/l), hemoglobin A1c ≥6.5% (48 mmol/mol), or current use of anti-diabetic drug. Multiple logistic regression analysis was used to calculate odds ratio of diabetes for each category of overtime.

Results

After adjustment for age, sex, company, smoking, and BMI, there was a suggestion of U-shaped relationship between overtime work and prevalence of diabetes (P for quadratic trend = 0.07). Compared with those who worked <45 hours of overtime per month, the adjusted odds ratios (95% confidence interval) of diabetes were 0.86 (0.77–0.94), 0.69 (0.53–0.89), and 1.03 (0.72–1.46) for those who worked 45–79, 80–99, and ≥100 hours of overtime per month, respectively. In one company (n = 33,807), where other potential confounders including shift work, job position, type of department, alcohol consumption, sleep duration, leisure time physical activity, and family history of diabetes was additionally adjusted for, similar result was obtained (P for quadratic trend = 0.05).

Conclusions

Long hours of overtime work may not be associated with increased prevalence of diabetes among Japanese workers.     

Reversible hyporeninemic hypoaldosteronism in a patient with tetraplegia

A 66-year-old man with tetraplegia developed hyperkalemia. Hyporeninemic hypoaldosteronism was disclosed on the basis of a lack of response of plasma renin activity to furosemide administration or tilting with marked hypotension and a subnormal response of aldosterone to furosemide stimulation, tilting, angiotensin II infusion and ACTH administration, as well as increased vascular responsiveness to angiotensin II infusion. Of interest was the finding that urinary excretion of epinephrine and norepinephrine was markedly reduced, indicating that hyporeninemia may possibly be due to a chronic lack of sympathetic nervous stimuli. The patient was treated with sodium polystyrene sulfonate resin and/or 9-alpha-fluorohydrocortisone, and wheelchair rehabilitation. However, even after stopping 8-month-mineralcorticoid replacement, normokalemia was maintained. Reexamination of the renin-angiotensin-aldosterone system revealed a normalized response to tilting or ACTH administration along with the normal catecholamine excretion. One more point to be noted is that ACTH administration resulted in a rise in the plasma levels of cortisol, corticosterone and 18-OH-corticosterone, but not aldosterone. This may be attributed to ACTH-stimulated 18-OH-corticosterone derived from the zona fasciculata or alternatively to a partial defect of corticosterone methyl oxidase type II (18-dehydrogenase) in the adrenal glomerulosa cells. These results suggested that hyporeninemic hypoaldosteronism may have been attributable to a decrease in systemic nervous stimuli and that such abnormalities were reversible.     

The pharmacokinetic properties of methamphetamine in rats with previous repeated exposure to methamphetamine: the differences between Long-Evans and Wistar rats.

Repeated treatment with methamphetamine (METH) causes long-term behavioral changes, so-called behavioral sensitization (BS), in humans as well as experimental animals. However, there are no reports as to whether repeated METH treatment can establish BS in stress-sensitive Long-Evans (LE) rats. Thus, we investigated the effect of repeated METH treatment (5 mg/kg x 5 days) on the establishment of BS in LE rats. Wistar (WIS) rats were used as a reference. In LE rats, repeated METH treatment failed to cause BS although it did enhance METH-induced hyperlocomotion in WIS rats. The levels of METH in brain dialysate and the ratio of the area under the concentration-time curve area in plasma to that in brain dialysate was increased in repeated METH-treated WIS rats as reported previously, but not in repeated METH-treated LE rats. METH increases plasma corticosterone (CORT) in both strains. However, the intensity of increment of CORT by repeated METH was lower in LE rats than that in WIS rats. Repeated METH treatment decreased the expression of METH-transposable and CORT-sensitive transporter, organic cation transporter 3 (OCT3), in the brain of WIS rats. However, the intensity of the decrement of OCT3 with repeated METH treatment was similar between both strains. Taken together, these results suggest that the lack of establishment of BS in LE rats might have been caused by the unchanged brain penetration of METH after repeated METH administration, and that the differential CORT response to METH is an important strain difference.     

Eugregarines reduce susceptibility of the hide beetle, Dermestes maculatus, to apicomplexan pathogens and retard larval development

Eugregarines are abundant in a great diversity of invertebrates, and yet their relationships with their hosts are subject to controversy and confusion. We tested the effect of the eugregarine, Pyxinia crystalligera, on growth, development, and susceptibility to two Apicomplexa pathogens of the hide beetle, D. maculatus. Heavy infection with eugregarines provided partial protection from two pathogenic members of Apicomplexa, M. trogodermae and A. tribolii. Infection with P. crystalligera caused lower weight in beetle larvae, but did not significantly retard pupation or adult emergence. A. tribolii infection of Lepidoptera and M. trogodermae infection of D. maculatus are reported for the first time.     

Functional Consequences of Sulfhydryl Modification of the γ-Aminobutyric Acid Transporter 1 at a Single Solvent-Exposed Cysteine Residue

The aims of this study were to optimize the experimental conditions for labeling extracellularly oriented, solvent-exposed cysteine residues of ??-aminobutyric acid transporter 1 (GAT1) with the membrane-impermeant sulfhydryl reagent [2-(trimethylammonium)ethyl]methanethiosulfonate (MTSET) and to characterize the functional and pharmacological consequences of labeling on transporter steady-state and presteady-state kinetic properties. We expressed human GAT1 in Xenopus laevis oocytes and used radiotracer and electrophysiological methods to assay transporter function before and after sulfhydryl modification with MTSET. In the presence of NaCl, transporter exposure to MTSET (1?C2.5?mM for 5?C20?min) led to partial inhibition of GAT1-mediated transport, and this loss of function was completely reversed by the reducing reagent dithiothreitol. MTSET treatment had no functional effect on the mutant GAT1 C74A, whereas the membrane-permeant reagents N-ethylmaleimide and tetramethylrhodamine-6-maleimide inhibited GABA transport mediated by GAT1 C74A. Ion replacement experiments indicated that MTSET labeling of GAT1 could be driven to completion when valproate replaced chloride in the labeling buffer, suggesting that valproate induces a GAT1 conformation that significantly increases C74 accessibility to the extracellular fluid. Following partial inhibition by MTSET, there was a proportional reduction in both the presteady-state and steady-state macroscopic signals, and the functional and pharmacological properties of the remaining signals were indistinguishable from those of unlabeled GAT1. Therefore, covalent modification of GAT1 at C74 results in completely nonfunctional as well as electrically silent transporters.     

Molecular variability of Spodoptera frugiperda (Lepidoptera: Noctuidae) populations associated to maize and cotton crops in Brazil

The molecular variability among 10 populations of Spodoptera frugiperda (J.E. Smith), collected from maize, Zea mays L., or cotton Gossypium hirsutum L. crops located at distinctive geographical regions in Brazil, was assessed through random amplification of polymorphic DNA (RAPD)-polymerase chain reaction (PCR). In total, 208 RAPD markers were evaluated, and 98% of them were polymorphic. The mean genetic similarity was 0.6621 and 0.2499 by the Simple Matching and Jaccard matrices, respectively. In general, the unweighted pair-group method with arithmetic average dendrograms separated the populations into clusters related to the geographical origin of the samples. No branch of the dendrograms underpinning a molecular association of S. frugiperda has been identified to either of the two host plants. The molecular variance analysis showed that 18 and 82% of the genetic variation was distributed among and within the groups of populations, respectively. The principal coordinate analysis reinforced the pattern of population clustering found with the unweighted pair-group method with arithmetic average method. These results suggest the occurrence of considerable gene flow between S. frugiperda populations from maize and cotton fields located in the same region in Brazil. Therefore, for an effective management of this pest, there is an urgent need for a better understanding of the gene flow of S. frugiperda populations associated to different host plants along the distribution range of this pest over time in a specific cropping system.     

Human mast cell chymase cleaves pro-IL-18 and generates a novel and biologically active IL-18 fragment

Increased release of IL-18 in the skin causes atopic dermatitis (AD)-like skin lesions, suggesting a role of IL-18 in the pathogenesis of AD. Caspase-1 is a well-known activator of IL-18, but caspase-1 knockout mice still have biologically active IL-18. Normal human keratinocyte constitutively produces pro-IL-18, but it is unable to activate it, suggesting the existence of an alternative pathway for IL-18 in the skin. Dermal accumulation of mast cells is commonly observed in AD patients and in experimental mouse models of AD. Connective tissue mast cells contain high amounts of chymase and tryptase in their cytoplasmic granules. In the present study, we demonstrated that activation of IL-18 is a novel function of human mast cell chymase. Human mast cell chymase rapidly cleaves recombinant pro-IL-18 at 56-phenylalanine and produces a biologically active IL-18 fragment that is smaller than any other reported IL-18-derived species. The human mast cell chymase and the novel IL-18-derived active peptide may be novel therapeutic targets in AD- and IL-18-associated diseases.