Molecular alterations in apoptotic pathways after PKB/Akt-mediated chemoresistance in NCI H460 cells

Protein kinase B/Akt has been described as a central mediator of antiapoptotic signals in cancer cells. Furthermore, Akt has been shown to affect cell cycle progression and proliferative pathways and to possess a potential function in tumorigenesis and chemoresistance. In this study, we show that the ectopic expression of a constitutively active form of Akt1 (CA-Akt1) results in enhanced chemoresistance of NCI H460 human NSCLC cells towards a panel of chemotherapeutic agents. To understand the molecular alterations leading to impaired chemosensitivity mediated by activated Akt, we analysed various apoptotic pathways, including the activation of p53, caspases 3, 7, 8, and 9, release of cytochrome c from mitochondria, and the expression levels of pro- and antiapoptotic proteins such as Bcl-2, Bcl-x_L, Bcl-x_s, Bax, or Bfl-1. We observed that expression of CA-Akt did not interfere with single defined apoptotic switches, but modulated the apoptotic threshold of several apoptotic pathways towards increasing the threshold of onset. In particular, we found that CA-Akt-expressing cells displayed increased expression of the antiapoptotic Bcl-2 family member protein Bcl-x_l, and a delayed onset of the p53 pathway after treatment with cisplatin or Mitoxantrone. Thus, our data suggest that Akt mediates chemoresistance in NHI H460 cells by interfering with and delaying the onset of various apoptotic pathways. A complete inactivation of apoptotic pathways was observed in none of the molecular alterations investigated. Our data strengthen the role of Akt as a central mediator of cell survival signals and/or chemoresistance and as an attractive target for cancer cell chemosensitisation.

Combined ACTH and glucocorticoid treatment improves survival and organ maturation in premature newborn calves

Glucocorticoids play an important role in prenatal organ maturation in many species. In humans, maternal treatment with synthetic glucocorticoids improves neonatal adaptation of prematurely born infants. In cows, pre-term calf survival is improved following a single maternal glucocorticoid administration. We hypothesized that stimulation of endogenous cortisol secretion by adrenocorticotropin (ACTH) treatment combined with maternal dexamethasone treatment, would be even more efficient in stimulating organ maturation in the prematurely delivered calf. Three groups of premature calves were delivered by caesarian section at 90% of gestation length from dams which were either untreated or injected with dexamethasone before delivery, combined with either prenatal or postnatal ACTH treatment to the calf. During the first 24h after birth, thermoregulation, blood chemistry, liver values and organ weights were recorded. In the untreated calves, survival was significantly correlated with blood oxygenation, sodium and calcium levels at the moment of birth. There were marked maturational effects of the treatments on body temperature regulation, blood acid-base status, oxygenation, glucose, insulin, IGF-1 levels, weight of the heart, liver, gastrointestinal tract and thymus weight. For many of the measured metabolic, endocrine and organ weight parameters, the intrauterine ACTH treatment was associated with improved values relative to the postnatal ACTH treatment, which appeared to have no immediate effect on calf viability. In conclusion, the premature calf delivered by caesarian section at 90% of gestation length showed blood chemistry, metabolic, endocrine and organ growth characteristics that indicated severe prematurity. However, the maturation of organ function in newborn premature calves following maternal glucocorticoid injections was further enhanced if is was preceded by intra-fetal injections of ACTH.

The relation of markers of fetal growth with asthma, allergies and serum immunoglobulin E levels in children at age 5-7 years

BACKGROUND

It has been suggested that fetal growth and maturation have an impact on the development of allergic diseases later in life.

OBJECTIVE

To examine the association between measures of fetal growth and allergic disease in children at age 5-7 years.

METHODS

As part of the German International Study of Asthma and Allergies in Childhood phase II surveys, a random sample of school beginners (n=1138) was examined in 1995. Data on anthropometric measures at birth and gestational age were obtained from maternal copies of birth records. Data on symptoms and doctor-diagnosed asthma, atopic dermatitis and hayfever were gathered by parental questionnaires. Atopic sensitization was assessed by serum IgE and skin prick tests to common aeroallergens. Children (741) had complete data for the explanatory variables of interest and were thus eligible for this analysis. Confounder-adjusted prevalence odds ratios (PORs) and means ratios with 95% confidence intervals (CI) were calculated using multiple logistic and linear regression.

RESULTS

Birth weight and gestational age were positively associated with atopic sensitization (Ptrend=0.025 and 0.035, respectively). Children with a low birth weight relative to head circumference had a decreased risk of sensitization (POR 0.44, 95% CI 0.21-0.91; Ptrend=0.020). Moreover, total serum IgE increased with increasing birth weight (Ptrend=0.042). No consistent relationship was observed between markers of fetal growth and wheezing, doctor-diagnosed asthma, atopic dermatitis and hayfever.

CONCLUSION

These data suggest that fetal growth and maturity are associated with atopic sensitization and total serum IgE levels in childhood.

Imaging lung function using rapid dynamic acquisition of T 1-maps during oxygen enhancement

This paper describes imaging of lung function with oxygen-enhanced MRI using dynamically acquired T1 parameter maps, which allows an accurate, quantitative assessment of time constants of T1-enhancement and therefore lung function. Eight healthy volunteers were examined on a 1.5-T whole-body scanner. Lung T1-maps based on an IR Snapshot FLASH technique (TE = 1.4 ms, TR = 3.5 ms, FA = 7 (composite function )) were dynamically acquired from each subject. Without waiting for full relaxation between subsequent acquisition of T1-maps, one T1-map was acquired every 6.7 s. For comparison, all subjects underwent a standard pulmonary function test (PFT). Oxygen wash-in and wash-out time course curves of T1 relaxation rate (R1)-enhancement were obtained and time constants of oxygen wash-in (w(in)) and wash-out (w(out)) were calculated. Averaged over the whole right lung, the mean w(out) was 43.90 +/- 10.47 s and the mean (w(in)) was 51.20 +/- 15.53 s, thus about 17% higher in magnitude. Wash-in time constants correlated strongly with forced expired volume in one second in percentage of the vital capacity (FEV1 % VC) and with maximum expiratory flow at 25% vital capacity (MEF25), whereas wash-out time constants showed only weak correlation. Using oxygen-enhanced rapid dynamic acquisition of T1-maps, time course curves of R1-enhancement can be obtained. With w(in) and w(out) two new parameters for assessing lung function are available. Therefore, the proposed method has the potential to provide regional information of pulmonary function in various lung diseases.

Polo-like kinase isoform expression is a prognostic factor in ovarian carcinoma

The Polo-like kinase (PLK) family comprises three serine/threonine kinases, functionally involved in signal transduction pathways essential for the accomplishment of mitosis in both normal and malignant cells. Moreover, certain PLKs have been functionally linked to cytoskeletal reorganisation. In this study, the expression of PLK1 and PLK3 was determined immunohistochemically in tissue specimen of normal ovaries (n=9), cystadenomas (n=17), borderline tumours (n=13) and ovarian carcinomas (n=77). PLK 1 and PLK3 expression was low in normal ovarian surface epithelium and borderline tumours, with moderately higher expression levels in cystadenomas. In ovarian carcinomas, 26% of cases were PLK1 positive and 50.6% of cases were PLK3 positive. A positive correlation of both PLK1 and PLK3 expression with indicators of mitotic frequency could be established. The overexpression of either isoenzyme had an impact on patient prognosis with shortened survival time for patients with tumours positive for PLK1 (P=0.02) and PLK3 (P=0.02), but only PLK1 expression remained a prognostic factor in multivariate survival analysis (P=0.03). The results of this study, if interpreted in the context of recently published functional data, suggest that inhibition of PLKs might represent an interesting new targeted approach for chemotherapy of epithelial ovarian cancer. Furthermore, this study suggests that PLK1 is a novel independent prognostic marker in ovarian carcinomas.

Spin singlet formation in MgTi2O4: evidence of a helical dimerization pattern

The transition-metal spinel MgTi2O4 undergoes a metal-insulator (M-I) transition on cooling below T(M-I)=260 K. A sharp reduction of the magnetic susceptibility below T(M-I) suggests the onset of a magnetic singlet state. Using high-resolution synchrotron and neutron powder diffraction, we have solved the low-temperature crystal structure of MgTi2O4, which is found to contain dimers with short Ti-Ti distances (the locations of the spin singlets) alternating with long bonds to form helices. Band structure calculations based on hybrid exchange density functional theory show that, at low temperatures, MgTi2O4 is an orbitally ordered band insulator.

A method to reduce the invasiveness of fetal catheterization in the cow

Surgical intervention in general anesthesia (GA) of the cow in late gestation is a stressful condition for both mother and fetus, potentially leading to premature delivery or fetal death. The present study hypothesized that fetal catheterization at days 246-253 (90% of gestation) is done with less physical and metabolic stress for the mother and fetus, when the surgery is performed on a standing cow and local anesthesia (LA) rather than on a recumbent cow in general anesthesia. Fetal and uterine maternal intra-vascular catheters were implanted during general anesthesia (GA, n=24) or local analgesia (LA, n=7). Blood gases and metabolite levels in the fetal calves and their mothers were measured during surgery and for 5 days post-operatively. During surgery, venous blood pH was higher (7.44 +/- 0.01 versus 7.39 +/- 0.01, P<0.05) and hemoglobin and oxygen contents lower in LA cows compared with GA cows (9.3 +/- 0.3 mg/dl versus 11.8 +/- 0.2 mg/dl, P<0.001 and 10.0 +/- 0.3 ml/dl versus 12.6 +/- 0.6 ml/dl, P<0.05). The differences between the two groups of fetuses reflected those of their dams in that LA fetuses showed lower arterial oxygen pressure (18.3 +/- 1.4 mmHg versus 24.8 +/- 1.4 mmHg, P<0.05) and hemoglobin (7.81 +/- 0.30 mg/dl versus 9.22 +/- 0.21 mg/dl P<0.01) and furthermore, they also showed higher blood glucose (2.4 +/- 0.2 mM versus 1.4 +/- 0.1 mM, P<0.01). During the 5 days post-surgery, 10 GA fetuses (42%) and 1 LA fetus (14%) died in utero. Bacterial contamination was implicated in six of the GA deaths and in the one LA death. In the dams with surviving calves, differences in hemoglobin (9.49 +/- 0.21 mg/dl versus 11.17 +/- 0.23 mg/dl P<0.001) and O2ct (10.9 +/- 0.3 ml/dl versus 12.5 +/- 0.5 ml/dl, P<0.05) were still present, and in addition, blood glucose was higher in LA versus GA cows (4.3 +/- 0.2 mM versus 3.8 +/- 0.1 mM, P<0.05). The choice of surgical method did not affect post-surgery blood chemistry in the surviving fetuses, except that the higher blood glucose in the LA fetuses at surgery tended to be maintained also post-operatively (2.0 +/- 0.2 mM versus 1.5 +/- 0.1 mM, P=0.07). The observed differences in blood chemistry parameters between the two methods of surgery and possibly in the fetal death may be explained by differences in catheterization method and the associated differences in physical and metabolic stress during and after surgery. Thus, surgery upon a standing cow in local anesthesia should be considered as an alternative to surgery in universal anesthesia for fetal catheterization in the cow in late gestation.

The dynamics of the hypothalamic-pituitary-adrenal axis during maternal deprivation

A close contact between the dam and the litter is essential for the normal development of the hypothalamic-pituitary-adrenal (HPA) axis in rats and mice. Maternal signals, as licking and feeding, have been shown to sustain the HPA axis of the pups in a hypo-responsive state. Disruption of this mother-pup interaction by 24 h of maternal deprivation activates the otherwise quiescent stress system of the neonates, resulting in an enhanced adrenal sensitivity to adrenocorticotropic hormone (ACTH) and a decreased expression of central HPA markers, such as corticotropin-releasing hormone (CRH). However, the dynamics of these central and peripheral changes over the 24h period are largely unknown. In this study, we examined the time course of some of the central and peripheral indices of HPA activity during 24 h of maternal deprivation. We measured corticosterone and ACTH in the blood as well as CRH, mineralocorticoid and glucocorticoid receptor expression in the brain. Our results demonstrate that each of the components of the HPA axis responds to maternal deprivation at different time points following removal of the mother and with a very specific time course. The main activation of the HPA axis occurred between 4 h and 8 h of maternal absence. By contrast, during the second half of the deprivation period, negativefeedback mechanisms restrained the further increase in ACTH and corticosterone release. We conclude that maternal deprivation triggers a cascade of sequential changes at the various levels of the stress system, and that measuring only one aspect of the system at one time point does not accurately reflect the dynamic alterations of the HPA axis.

Oxygen and silver clusters: transition from chemisorption to oxidation

We use the adsorption probabilities of molecular nitrogen and oxygen to study the physi- and chemisorption on small silver particles. The physisorption of nitrogen is governed by the structure of the particle surface. The sticking of oxygen additionally involves the electronic configuration of the metal cluster. At 77 K molecular oxygen sticks chemisorbed to the particles with a transfer of one electron. At temperatures above 105 K the chemisorption transforms into oxidation, invoking the dissociation of the oxygen molecule and the loss of a single oxygen atom.

No peri- and postnatal effects on calves born after transfer of in vitro produced embryos vitrified by the open pulled straw (OPS) method

The general objective of this study was to perform follow-up studies including selected peri- and postnatal characteristics on calves born after transfer of in vitro produced (IVP) embryos vitrified by the 'Open Pulled Straw' (OPS) method. An overall pregnancy rate of 16% after transfer of the OPS-vitrified IVP embryos was achieved and resulted in birth of 9 calves, with 11 AI calves serving as controls. There were no immediate or long-term effects on these calves with respect to birth weight, gestation length, perinatal mortality, growth rate, disease susceptibility and reproductive performance.