The Relationship between Sleep and Shift System, Age and Chronotype in Shift Workers

The purpose of this study was to investigate the effects of shift system, age, and chronotype on the sleep habits, sleepiness and catnaps of shift workers during night work. We administrated a Morningness-Eveningness Questionnaire and Life Habits Inventory to 561 male shift workers of three different shift systems in Korea. The mean scores on the Morningness-Eveningness Questionnaire clearly shifted toward the Morning type from the young to old groups. The waking and bedtimes during the day and evening shift were earlier for the older than for the younger groups, and these times were earlier across the Evening, Intermediate, to Morning type as well. Sleep length during the day shift was longer from the young to old, and it was shorter from the Evening, Intermediate, to Morning type. In the weekly rotation full-day 3-team 3-shift system and continuous full-day 3-team 3-shift system (which had earlier starting times for day shift) the sleep length of the younger workers was short. For the aged workers, sleep length during the night shift was short because they woke up early. In the weekly rotation full-day 2-team 2-shift system that had a short working interval, the reduction of sleep length during night shift was greater than that of the other shift systems. However, the scores on the Morningness-Eveningness Questionnaire showed a significantly negative correlation only in the bedtime during day shift among the sleep habit parameters for the independent variable by age. For the percentage of subjects that reported 'become sleepiness', the degree and time of sleepiness during the night shift were greater and earlier for the older than for the younger workers, and greater for the Morning than for the Evening type. The percentage of subjects who took a catnap during night shift, as well as the length of their catnap, were also higher and longer for the older groups, and higher and longer for the Morning type than for the Evening type. From these results, we surmised that the sleep habit parameters were influenced the age or shift systems rather than the chronotype. The sleep length during the night shift was shorter for the aged than for the young. In the shift systems that have a short working interval, the nocturnal was remarkably shorter for the young than the aged. The aged had not adapted their sleep for the night shift compared to the young, this suggested by the aged's strong complaint of sleepiness and by the fact that a larger percentage of aged subjects said they took catnaps during night shift compared to the younger workers.     

Clearance of false-positive antigen-antibody reactions of a diagnostic antigen produced inEscherichia coli with human sera

Although many pharmaceutically useful proteins are produced inE. coli expression system, it is very rare for the system to be used in the production of diagnostic antigen due to a major problem,i.e., false-positive reaction ofE. coli host-derived proteins contaminating purified diagnostic antigen with human sera. The N (nucleocapsid) protein of Seoul virus causing haemorrhagic fever with renal syndrome (HFRS) was produced inE. coli BL21 (DE3), and used for the detection of N protein-specific antibodies in human sera. Using the N protein as a diagnostic antigen of HFRS, the false-positive reaction was cleared by merely mixing the test sera with the extract ofE. coli host strain not harboring expression plasmid.     

High efficiency shoot regeneration from callus of quaking aspen (Populus tremuloides Michx.)

Callus was induced from leaf segments of aspen (Populus tremuloides Michx.) on modified B5 (mB5) medium with 0.1 mg/1 benzyladenine (BA) and 0.5 mg/1 2,4-dichlorophenoxyacetic acid (2,4-D). The resulting callus was either subcultured to solidified Woody Plant Medium (WPM) with 0.5 mg/1 BA directly for shoot regeneration or sieved into liquid mB5 medium for suspension culture. After 3 weeks of suspension culture, when the callus clumps grew to 3–4 mm in diameter, they were transferred onto solidified WPM with 0.5 mg/1 BA for shoot regeneration. Almost 100% of the clumps formed shoots on WPM when subcultured directly from mB5 with an average number of 6 shoots per callus. When transferred from suspension culture in mB5 to WPM, an average of 6 shoots per callus were produced from 51% of calli. These shoots could be easily rooted on either mB5 or WPM with 0.2 mg/1 indole-3-butyric acid (IBA) and transferred to pots. Transplanted plants were kept under intermittent mist for 2–4 weeks before normal growth in the green house.Abbreviations BA 6-Benzyl-adenine - IBA indole-3-butyric acid - 2,4-D 2,4-dichlorophenoxyacetic acid - mB5 medium modified B5 medium - WPM Woody Plant medium     

The synthesis of short- and long-chain acylarnitine by etio-chloroplasts of greening barley leaves

Etio-chloroplasts of barley, purified on sucrose density gradients were shown to possess carnitine long-chain acyltransferase (carnitine palmitoyltransferase, EC 2.3.1.21) activity and carnitine short-chain acyltransferase (carnitine acetyltransferase EC 2.3.1.7) activity. These enzymes may play a role in the transport of acyl groups as acylcarnitines through the membrane barrier of barley etio-chloroplasts and also ‘or alternatively’ may spare CoA by transferring short- and long-chain acyl groups from short-and long-chain acyl CoA to carnitine.     

Isolation and characterization of p19INK4d, a p16-related inhibitor specific to CDK6 and CDK4.

Cyclin-dependent kinases 4 and 6 are complexed with many small cellular proteins in vivo. We have isolated cDNA sequences, INK4d, encoding a 19-kDa protein that is associated with CDK6 in several hematopoietic cell lines. p19 shares equal similarity and a common ancestor with other identified inhibitors of the p16/INK4 family. p19 interacts with and inhibits the activity of both CDK4 and CDK6 and exhibits no detectable interaction with the other known CDKs. p19 protein is present in both cell nuclei and cytoplasm. The p19 gene has been mapped to chromosome 19p13.2, and the level of its mRNA expression varies widely between different tissues. In contrast to p21 and p27 whose interaction with CDK subunits is dependent on or stimulated by the cyclin subunit, the interaction of p19 and p18 with CDK6 is hindered by the cyclin protein. Binary cyclin D1-p18/p19 or cyclin D1-CDK6 complexes are highly stable and cannot be dissociated by excess amounts of cyclin D1 or p19/p18 proteins, suggesting that p16 inhibitors and D cyclins may interact with CDKs 4 and 6 in a competing or potentially mutually exclusive manner.     

Reactions of agostic manganese complexes with molecular hydrogen

Reactions between manganese agostic species having (Mn---C---H) interactions and molecular hydrogen have been investigated. Treatment of the bridging agostic cyclooctenylmanganese tricarbonyl, 3, and butenylmanganese tricarbonyl, 5, with hydrogen in benzene results in the formation of the cyclohexadienylmanganese tricarbonyl compound 4. This suggests that the hydrogen molecule is highly reactive toward organometallic manganese complexes containing an agostic C---H bond. In these reactions (η²-H₂) bonded species are plausible intermediates but these are not detected by NMR. The results indicate that the suggested intermediates in the reactions may be useful as hydrogenation catalysts and as precursors to prepare new manganese compounds which may not be accessible by other pathways.     

Insulin-induced oxidative neuronal injury in cortical culture: mediation by induced N-methyl-D-aspartate receptors

While effectively attenuating neuronal apoptosis in mouse cortical culture, insulin paradoxically induced neuronal necrosis with 48 h of exposure. The insulin neurotoxicity was blocked by an antioxidant but not by caspase inhibitors. Exposure to insulin led to tyrosine phosphorylation of the insulin receptor and the insulin-like growth factor-1 (IGF-1) receptor and activation of protein kinase C (PKC) and phosphoinositide 3-kinase (PI3-kinase). Inhibitors of tyrosine kinase and PKC, but not PI3-kinase, attenuated the insulin neurotoxicity. Conversely, the inhibitor of PI3-kinase but not PKC reversed the antiapoptotic effect of insulin. Suggesting that the gene activity-dependent emergence of excitotoxicity contributed to insulin neurotoxicity, macromolecule synthesis inhibitors and N-methyl-D-aspartate (NMDA) antagonists blocked it. Consistently, exposure to insulin increased the level of the NR2A subunit of the NMDA receptor without much altering NR1 or NR2B levels. The present study suggests that insulin can be both neuroprotective and neurotoxic in the same cell system but by way of different signaling cascades.     

Iron overload induces cerebral endothelial senescence in aged mice and in primary culture in a sex-dependent manner

Iron imbalance in the brain negatively affects brain function. With aging, iron levels increase in the brain and contribute to brain damage and neurological disorders. Changes in the cerebral vasculature with aging may enhance iron entry into the brain parenchyma, leading to iron overload and its deleterious consequences. Endothelial senescence has emerged as an important contributor to age-related changes in the cerebral vasculature. Evidence indicates that iron overload may induce senescence in cultured cell lines. Importantly, cells derived from female human and mice generally show enhanced senescence-associated phenotype, compared with males. Thus, we hypothesize that cerebral endothelial cells (CEC) derived from aged female mice are more susceptible to iron-induced senescence, compared with CEC from aged males. We found that aged female mice, but not males, showed cognitive deficits when chronically treated with ferric citrate (FC), and their brains and the brain vasculature showed senescence-associated phenotype. We also found that primary culture of CEC derived from aged female mice, but not male-derived CEC, exhibited senescence-associated phenotype when treated with FC. We identified that the transmembrane receptor Robo4 was downregulated in the brain vasculature and in cultured primary CEC derived from aged female mice, compared with those from male mice. We discovered that Robo4 downregulation contributed to enhanced vulnerability to FC-induced senescence. Thus, our study identifies Robo4 downregulation as a driver of senescence induced by iron overload in primary culture of CEC and a potential risk factor of brain vasculature impairment and brain dysfunction.     

Serum parathyroid hormone concentration measured by highly sensitive assay in post-thyroidectomy hypocalcemia of patients with Graves' disease

To investigate the role of parathyroid function in transient hypocalcemia after subtotal thyroidectomy for Graves' disease, the serum parathyroid hormone (PTH) concentration and nephrogenous (N) cAMP were measured in 16 patients before and after surgery. Serum PTH was measured with two commercially available kits (PTH-M, PTH-C), PTH-M is a recently developed highly sensitive assay using an antibody recognizing the mid-portion of human PTH and a synthetic 125I-tyr45-human PTH (43-68) as a radioligand. One of the 16 patients had severe clinical tetany and had a markedly lower PTH-M concentration and NcAMP after thyroidectomy. However, no significant change in serum PTH-M, PTH-C and NcAMP were observed in the other patients, although their serum calcium (Ca) concentrations decreased significantly. The Data were analyzed by dividing the patients according to the change in serum Ca or PTH. Serum PTH-M and PTH-C significantly decreased in 4 patients whose serum Ca clearly decreased after surgery. Serum Ca on the first postoperative day was significantly lower in patients whose serum PTH decreased after thyroidectomy than in patients whose serum PTH did not. Furthermore, the serum Ca concentration was significantly correlated with PTH-M, and with NcAMP on the third postoperative day. These data proved that hypofunction of the parathyroid gland is important in transient hypocalcemia after subtotal thyroidectomy for Graves' disease. The pathogenetic mechanism of transient hypocalcemia was discussed in comparison with the data from a patient who had overt parathyroid injury.     

Effect of open-field experimental warming on the leaf phenology of oriental oak (Quercus variabilis) seedlings

Aims An open-field warming experiment enables us to test the effects of projected temperature increase on change in plant phenology with fewer confounding factors and to study phenological response to temperature ranges beyond natural variability. This study aims to (i) examine the effect of temperature increase on leaf unfolding and senescence of oriental oak (Quercus variabilis Blume) under experimental warming and (ii) measure temperature-related parameters used in estimating phenological response to temperature elevation.Methods Using an open-field warming system with infrared heaters, we increased the air temperature by ~3°C in the warmed plots compared with that of the control plots consistently for 2 years. Leaf unfolding and senescence dates of Q. variabilis seedlings were recorded and temperature-related phenological parameters were analysed.Important findings The timing of leaf unfolding was advanced by 3–8 days (1.1–3.0 days/°C) and the date of leaf senescence was delayed by 14–19 days (5.0–7.3 days/°C) under elevated air temperatures. However, the cumulative degree days (CDD) of leaf unfolding were not significantly changed by experimental warming, which suggest the applicability of a constant CDD value to estimate the change in spring leaf phenology under 3°C warming. Consistent ranges of advancement and temperature sensitivity in spring phenology and delayed autumn phenology and proposed temperature parameters from this study might be applied to predict future phenological change.