Working hours and fatigue of Japanese flight attendants (FA).

There have been some reports concerning high complaint rates of fatigue or fatigue-related symptoms including lower back pain in flight attendants (FA). Thus, the relations of working conditions with work stress and fatigue symptoms were studied chiefly by focusing on working hours. From analysis of the time-table and fatigue symptoms of workers on international flights, it was suspected that there were some work-related factors jointly causing serious FA fatigue symptoms; night time and early morning work, long flight hours and a large time difference, thus disturbing their biological rhythms. On domestic flights, showing up early in the morning and debriefing late in the night were often observed together with a highly irregular FA time schedule. By statistical analyses, some factors including long working hours, frequent landing and late debriefing hours were considered to contribute significantly to the high fatigue complaint rates. Thus, it should be emphasized that many countermeasures are necessary to improve FA working conditions including working hours, rest on the airplane (ONO et al., 1990) and sleep during layover, in order to reduce their work stress and fatigue symptoms.     

Brain metabolic activity associated with long-term memory consolidation

The use of day-old chickens trained on a single-trial passive avoidance task provides a useful paradigm for investigations into cellular mechanisms underlying memory formation. Pharmacological intervention studies indicate that there are three temporally identifiable stages of memory processing leading to the consolidation of information for this task. These stages, designated as short-term (STM; up to 15 min), intermediate-term (ITM; 15-55 min), and long-term (LTM; more than 55 min) memory, have been found to be sequentially dependent (Ng and Gibbs, 1989). In addition, ITM appears to consist of two physiologically distinguishable phases, A and B. Evidence in this laboratory suggests that the crossover between these ITM phases (at 30 min after training) represents a critical time-point for the triggering of LTM.     

Mechanism of inhibition of peptide chain initiation by amino acid deprivation in perfused rat liver. Regulation involving inhibition of eukaryotic initiation factor 2 alpha phosphatase activity.

In previous studies, initiation of protein synthesis was shown to be inhibited in perfused rat livers deprived of single essential amino acids. In the present study, histidinol, a competitive inhibitor of histidinyl-tRNA synthetase, was used to amplify the effects of histidine deprivation on protein synthesis in perfused liver to facilitate investigation of mechanisms involved in the inhibition of peptide chain initiation. Protein synthesis was reduced to 77% of the control rate in livers deprived of histidine and to 13% of the control rate in livers deprived of histidine and exposed to 2.0 mM histidinol. The inhibition of protein synthesis caused by histidine deprivation alone was accompanied by a 2-fold increase in the number of free ribosomal particles, a 29% decrease in Met-tRNA(i) binding to 43 S preinitiation complexes, and a 31% reduction in activity of eukaryotic initiation factor 2B (eIF-2B). By comparison, histidine deprivation combined with histidinol addition resulted in a 3-fold increase in free ribosomal particles, a 66% decrease in Met-tRNAi binding, and a 78% reduction in eIF-2B activity. The proportion of the alpha-subunit of eukaryotic initiation factor two (eIF-2) in the phosphorylated form increased from 8.9 +/- 0.8% in control livers to 52.4 +/- 5.5% in response to histidinol. The increase in the amount of eIF-2 alpha in the phosphorylated form apparently was not due to an increase in kinase activity, because there was no change in eIF-2 alpha kinase activity in extracts of liver perfused with medium containing histidinol compared to controls. Instead, the increased phosphorylation of eIF-2 alpha was associated with an inhibition of eIF-2 alpha phosphatase activity. Thus, in contrast to other systems that have been examined, the mechanism involved in the increase in the phosphorylation state of eIF-2 alpha appears to involve an inhibition of eIF-2 alpha phosphatase activity rather than activation of an eIF-2 alpha kinase.     

Morphometry, densitometry and pattern analysis of plastic-embedded histologic material from urothelial cell carcinoma of the bladder.

An image analysis method of grading histologic sections of bladder carcinoma was tested. The method was new in four respects. First, for fixation of the biopsies a coagulant fixative was used. Second, 2-microns plastic sections were used to ensure the reproducibility of nuclear imaging. Third, a new stereologic approach was used for calculation of the nuclear volume and DNA content. Fourth, for the classification rule the morphometric, densitometric and texture features were used in concert. The IBAS 2000 instrument was used for the measurements. Texture analysis of the chromatin patterns was performed using Markovian texture features. Using discriminant analysis, of 22 parameters, 2 morphometric, 2 densitometric and 3 texture features were selected for the classification rule. With them, 89% of the bladder carcinomas were correctly classified into the three grades. All grade III tumors were classified correctly. Among the features tested, the densitometry of the DNA had the highest F values. All of the grade III tumors and 45% of the grade II tumor group had DNA histograms indicating aneuploidy. This study showed that plastic-embedded material is well suited to morphometry and densitometry and can be used for quantitative grading of bladder carcinoma.     

Genetic mapping of the gene for androgen-binding protein/sex hormone-binding globulin to mouse chromosome 11

Southern blot analysis of DNAs from Chinese hamster x mouse and rat x mouse somatic cell hybrids showed that the mouse gene encoding androgen-binding protein/sex hormone-binding globulin (ABP-SHBG) is on Chromosome 11. Progeny from an intersubspecies backcross were analyzed to position this locus, termed Shbg, between Il-3 and Int-4 in the middle of this chromosome. Shbg is thus closely linked to several neurological mutations, one of which, Tr, is also associated with male sterility. The recent finding that ABP-SHBG is found throughout the rat brain raises the possibility that one of these mutations may be due to a defect in Shbg.     

Electrostatic interaction between ion-penetrable multi-layered membranes

A theory of the double layer interaction regulated by the Donnan potential between two ion-penetrable membranes in an electrolyte solution developed previously by Ohshima and Kondo is extended to the case in which the membranes consist of many layers having different thickness and densities of membrane-fixed charges. The interaction force is found to be determined mainly by the contributions from layers located within the depth of 1/kappa (kappa, Debye-Hückel parameter) from the membrane surface. It is also predicted that the interaction force may alter its sign with changing electrolyte concentration.     

Interaction of the release factors with the Escherichia coli ribosome: structurally and functionally-important domains.

There are two major domains of interaction between the Escherichia coli release factors (RF-1 and RF-2) and each subunit of the ribosome. RF-2 has a binding domain on the shoulder and lower head region of the small subunit at the small lobe distant from the decoding site. This is in close proximity to one of the domains on the large subunit which includes the body dimer of L7/L12 and L11. The other domains of interaction, at the decoding site on the small subunit, and at the peptidyltransferase centre of the large subunit of the ribosome, are some distance from the first two, although the evidence for direct contact with the ribosome is less comprehensive. The release factors may therefore have two distinct structural domains, and in support of this concept RF-1 and RF-2 can both be cleaved into two fragments by papain. Region-specific antibodies, and antibodies against defined peptide within the RF sequences have given an indication that a significant part of an interacting RF molecule is in close proximity to the ribosome surface, confirming an observation by immunoelectron microscopy which suggested that the RF penetrates deeply into the cleft between the two subunits. A region of highly conserved primary sequence between the two release factors from E coli is also conserved in those from B subtilis suggesting it forms an important structural or functional domain. Antibodies against peptides from the N-terminal end of this region strongly inhibit binding of the RF to the ribosome.     

A follow-up study of 85 patients with Graves' disease in remission who developed undetectable serum thyroid-stimulating hormone concentrations using sensitive TSH assays.

Eighty-five patients with Graves' disease in clinical remission after treatment for over 1 year by methimazole therapy (36 patients, group A) or subtotal thyroidectomy (49 patients, group B) who became undetectable for serum thyrotropin levels (TSH less than 0.05 mU/l), were further followed for 1 year or more. Eight patients in group A (22%) and 7 patients in group B (14%) relapsed. Eleven patients in group A (30%) and 5 patients in group B (10%) had fluctuating patterns of free T4 in the upper normal to slightly supranormal range indicative of subclinical hyperthyroidism. The remaining patients continued to have undetectable TSH levels or restored normal TSH levels and normal thyroid hormone concentrations in sera. The results of the present study indicate that the occurrence of undetectable serum TSH concentrations in Graves' disease patients previously treated with methimazole or surgery are not necessarily predictive of clinical relapse because the eventual outcome is variable.     

Identification of endogenous sugar-binding proteins in the accessory sex glands of NMRI mice. A histochemical and biochemical study

In the present study we report on the histotopographical distribution of carbohydrate-binding proteins in the prostate and seminal vesicle of sexually mature NMRI mice using a panel of fluorescein-isothiocyanate labelled neoglycoproteins and asialoglycoproteins. Additionally, biochemical analysis using affinity chromatography and SDS-gel electrophoresis was performed to purify and characterize the respective proteins from the tissue. Our histochemical results clearly demonstrate the presence of endogenous receptors for the carbohydrate part of glycoconjugates in both glands. In the prostate a distinct staining was seen after incubation with melibiose-BSA-FTC, glucuronic acid-BSA-FTC and asialofetuin-FTC (only in the ventral prostate). In the epithelium of the seminal vesicle a weak staining occurred after incubation with asialofetuin-FTC and maltose-FTC. In the stroma of both accessory sex glands a distinct binding of several (neo)glycoproteins specific for beta-galactoside-binding proteins was observed which could be attributed to a beta-galactoside-binding lectin. Indeed biochemical analysis ascertained presence of such a histochemically detectable activity. We assume that the carbohydrate-binding proteins of the stroma, which were obviously linked to the elastic fibers, could play a role in the organisation of the extracellular matrix in the interstitium of the glands.     

Effect of nickel on oxygen free radical metabolism

The effect of nickel on superoxide dismutase activity (SOD), as well as on rate of hydroxydopamine oxidation, was studied in vitro since lipid peroxidation has been implicated in cell damage by nickel, whose toxicity and carcinogenicity are well established. Nickel strongly inhibits SOD activity. The degree of inhibition is directly proportion to the nickel concentration (tested range 0.066 to 0.33 microgram/mL in the reaction mixture); to the substrate concentration (tested range 0.4 x 10 4M to 1.1 x 10 4M 6-hydroxydopamine); and to reaction mixture. Autoxidation of 6-hydroxydopamine was increased by nickel concentrations higher than 15 micrograms/mL. The combination of excessive oxygen free radical production and inhibition of their elimination by inhibition of SOD activity may contribute to the nickel toxicity that has been reported in industrial accidents, as well as to the high incidence of cancer occurring in nickel workers. It may also contribute to many complications in uremic patients, in whom increased serum nickel levels were reported to be in a similar range to those inhibiting SOD.