Variations of Arterial Responses in vitro in Different Sections of Rat Main Superior Mesenteric Artery

Abstract: We examined the control of vascular tone in rat main superior mesenteric artery. Three standard rings (3 mm in length) of the mesenteric artery were cut, beginning 5 mm, 13 mm and 21 mm distally from the mesenteric arteryaorta junction. In noradrenaline-precontracted rings, relaxations to acetylcholine in the absence and presence of the cyclooxygenase inhibitor diclofenac, did not differ in the studied sections. However, the nitric oxide synthase inhibitor, N^G-nitro-L-arginine methyl ester, attenuated the diclofenac-resistant responses to acetylcholine more effectively in the proximal than the distal section. Glibenclamide, an inhibitor of ATP-sensitive K⁺ channels, diminished relaxations evoked by acetylcholine only in the distal section, whereas the inhibitor of Ca²⁺ activated K⁺ channels, apamin, attenuated the responses in all sections. Furthermore, relaxation sensitivity to nitroprusside and isoprenaline was lower in the proximal than distal section. Arterial contractile sensitivity to noradrenaline and potassium chloride was higher, while the maximal contractile force generation was lower in the proximal than the distal part. In conclusion, in different sections of rat main superior mesenteric artery considerable variability was observed in vasoconstrictor and vasodilator responses, as well as in the contribution of endothelial nitric oxide and endothelium-mediated hyperpolarization to vasodilation. Therefore, the present results emphasize the fact that only corresponding vessel segments should be used when investigating the control of arterial tone.     

Increased expression of telomerase RNA component is associated with increased cell proliferation in human astrocytomas.

Deregulation of telomerase, a ribonucleoprotein polymerase that compensates progressive loss of telomeric (TTAGGG)n repeats during DNA replication, has been suggested to facilitate tumorigenesis and cellular immortality by providing unlimited proliferation capacity for cancer cells. We investigated the relationship between tumor proliferation activity and in situ expression of the telomerase RNA component in 46 human grade I to IV astrocytomas. Heterogeneously distributed telomerase RNA expression was detected from all of the tumor samples as well as from normal human brain tissue. However, expression of telomerase RNA was significantly increased in highly malignant tumors (P = 0.024) and in tumors that showed increased proliferation activity determined by MIB-1 immunohistochemistry (P = 0.014). Interestingly, increased telomerase RNA levels were observed in a subgroup of grade II astrocytomas that showed significant increase in proliferation activity (P = 0.047), indicating that the telomerase RNA component is up-regulated already in early states of astrocytoma malignancy. Telomeric repeats amplification assays revealed telomerase activity in 4 of 6 glioblastomas and in 1 rapidly proliferating grade II astrocytoma. These results suggest that increased tumor proliferation activity triggers telomerase activation via mechanisms that involve increased production of the telomerase RNA component.     

Sleep-wake rhythm in an irregular shift system

Sleep in shift work has been studied extensively in regular shift systems but to a lesser degree in irregular shifts. Our main aim was to examine the sleep-wake rhythm in shift combinations ending with the night or the morning shift in two irregular shift systems. Three weeks' sleep/work shift diary data, collected from 126 randomly selected train drivers and 104 traffic controllers, were used in statistical analyses including a linear mixed model and a generalized linear model for repeated measurements. The results showed that the sleep-wake rhythm was significantly affected by the shift combinations. The main sleep period before the first night shift shortened by about 2 h when the morning shift immediately preceded the night shift as compared with the combination containing at least 36 h of free time before the night shift (reference combination). The main sleep period before the night shift was most curtailed between two night shifts, on average by 2.9 and 3.5 h among the drivers and the controllers, respectively, as compared with the reference combination. Afternoon napping increased when the morning or the day shift immediately preceded the night shift, the odds being 4.35-4.84 in comparison with the reference combination. The main sleep period before the morning shift became 0.5 h shorter when the evening shift preceded the morning shift in comparison with the sleep period after a free day. The risk for dozing off during the shift was associated only with the shift length, increasing by 17 and 35% for each working hour in the morning and the night shift, respectively. The results demonstrate advantageous and disadvantageous shift combinations in relation to sleep and make it possible to improve the ergonomy of irregular shift systems.     

Alpha2A-adrenoceptors are important modulators of the effects of D-amphetamine on startle reactivity and brain monoamines.

Amphetamines are commonly used to treat attention-deficit hyperactivity disorder, but are also widely abused. They are employed in schizophrenia-related animal models as they disrupt the prepulse inhibition (PPI) of the acoustic startle response. The behavioral effects of amphetamines have mainly been attributed to changes in dopamine transmission, but they also involve increases in the synaptic concentrations of norepinephrine (NE). alpha2-Adrenoceptors (alpha2-ARs) regulate the excitability and transmitter release of brain monoaminergic neurons mainly as inhibitory presynaptic auto- and heteroreceptors. Modulation of acoustic startle and its PPI by the alpha2A-AR subtype was investigated with mice lacking the alpha2A-AR (alpha2A-KO) and their wild-type (WT) controls, without drugs and after administration of the alpha2-AR agonist dexmedetomidine or the antagonist atipamezole. The interaction of D-amphetamine (D-amph) and the alpha2-AR-noradrenergic neuronal system in modulating startle reactivity and in regulating brain monoamine metabolism was assessed as the behavioral and neurochemical responses to D-amph alone, or to the combination of D-amph and dexmedetomidine or atipamezole. alpha2A-KO mice were supersensitive to both neurochemical and behavioral effects of D-amph. Brain NE stores of alpha2A-KO mice were depleted by D-amph, revealing the alpha2A-AR as essential in modulating the actions of D-amph. Also, increased startle responses and more pronounced disruption of PPI were noted in D-amph-treated alpha2A-KO mice. alpha2A-AR also appeared to be responsible for the startle-modulating effects of alpha2-AR drugs, since the startle attenuation after the alpha2-AR agonist dexmedetomidine was absent in alpha2A-KO mice, and the alpha2-AR antagonist atipamezole had opposite effects on the startle reflex in alpha2A-KO and WT mice.     

The Association of Time to Organ Procurement on Short- and Long-Term Outcomes in Kidney Transplantation

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Ovarian-adrenal cross-talk in polycystic ovary syndrome: evidence from wedge resection

OBJECTIVE: To determine whether the ovary influences adrenal androgen secretion in women with polycystic ovary syndrome (PCOS). DESIGN: Six PCOS-affected patients with clomiphene resistance and gonadotrophin hyperresponsivity, and six controls with regular ovulatory cycles, matched for age and body mass index. METHODS: Bilateral ovarian wedge resection was performed to induce ovulation surgically for these refractory women with PCOS. The adrenal androgen secretions were evaluated in PCOS patients before and again 6 months after this surgery, and in the controls, using an ACTH stimulation test (0.25mg synthetic ACTH(1-24)). RESULTS: Biochemically, basal levels and the maximum net increases (Delta) of 17-hydroxyprogesterone (17-OHP) and androstenedione, Delta17-OHP/Delta progesterone and Delta androstenedione/Delta17-OHP ratios in response to exogenous ACTH were significantly higher in PCOS patients before operation than those of controls. This purely ovarian surgery in women with PCOS was found to significantly reduce their basal androstenedione, testosterone and LH levels, insulin/glucose ratio, and post-corticotrophic Delta17-OHP, Delta androstenedione, Delta17-OHP/Delta progesterone and Delta androstenedione/Delta17-OHP, without obvious changes in FSH, oestradiol, sex hormone-binding globulin, Delta dehydroepiandrosterone, Delta dehydroepiandrosterone sulphate, Delta aldosterone and Delta cortisol values. CONCLUSIONS: Ovarian hyperandrogenicity from polycystic ovary may contribute to the enhanced adrenal P450c17alpha activity and subsequent Delta(4) androgen reserve revealed by the pharmacological corticotrophin stimulation in our special PCOS cases.     

The effects of weight management programs on self-esteem in pediatric overweight populations

OBJECTIVE: Review published findings on self-esteem and pediatric overweight, and changes in self-esteem subsequent to weight management programs. METHODS: We used PsycInfo and MedLine searches to identify peer-reviewed journal articles examining self-esteem changes following participation in weight management programs. RESULTS: Data regarding the relationship between self-esteem and obesity is mixed. Factors that place overweight children "at-risk" for low self-esteem include early adolescence, female gender, identification with majority cultural standards of body shape, exposure to teasing and peer victimization, a history of greater parental control over feeding, and internal attributions about weight status. Data from intervention studies suggest positive effects on self-esteem across settings. Components related to self-esteem improvements include weight change, parent involvement, and group intervention format. CONCLUSIONS: Well-designed, longitudinal studies using multidimensional measures of self-esteem, and following CONSORT guidelines are needed to confirm and expand these findings. Emphasis should be placed on examining mediators and moderators of self-esteem change.     

DDOST, PRKCSH and LGALS3, which encode AGE-receptors 1, 2 and 3, respectively, are not associated with diabetic nephropathy in type 1 diabetes

Aims/hypothesis  

The AGE receptors 1, 2 and 3, which are encoded by DDOST, PRKCSH and LGALS3, respectively, may be involved in the pathogenesis of diabetic complications. We sought to find out whether these genes are associated with diabetic nephropathy, cardiovascular disease and type 1 diabetes or related quantitative traits.