Vitellogenesis and oocyte development in azadirachtin-induced fifth-instar overage nymphs of Locusta migratoria (L.)

Injection of azadirachtin into females of Locusta migratoria at the beginning of the last nymphal instar prevented molting to the adult stage, and many of these locusts survived for long periods as overage fifth-instar nymphs. Overage female nymphs synthesized vitellogenin; maximum vitellogenin content in their hemolymph was 6–7 times higher than that found in normal adult females. The overage female nymphs developed vitellogenic oocytes, but development was retarded to some extent: although vitellogenin did accumulate in the proximal oocytes, their maximum average length was only about 2.8 mm (compared to 6.2 mm in normal adult females) and extensive oocyte resorption was observed. Thus, attainment of adult competence of the organs and processes involved in female reproduction is independent to a considerable extent from the process of overt adult morphogenesis.     

Choosing in Freedom or Forced to Choose? Introspective Blindness to Psychological Forcing in Stage-Magic

We investigated an individual ability to identify whether choices were made freely or forced by external parameters. We capitalized on magical setups where the notion of psychological forcing constitutes a well trodden path. In live stage magic, a magician guessed cards from spectators while inquiring how freely they thought they had made the choice. Our data showed a marked blindness in the introspection of free choice. Spectators assigned comparable ratings when choosing the card that the magician deliberately forced them compared to any other card, even in classical forcing, where the magician literally handles a card to the participant This observation was paralleled by a laboratory experiment where we observed modest changes in subjective reports by factors with drastic effect in choice. Pupil dilatation, which is known to tag slow cognitive events related to memory and attention, constitutes an efficient fingerprint to index subjective and objective aspects of choice.     

Integrin regulation by vascular endothelial growth factor in human brain microvascular endothelial cells: role of alpha6beta1 integrin in angiogenesis

The precise role of vascular endothelial growth factor (VEGF) in regulating integrins in brain microvascular endothelial cells is unknown. Here, we analyzed VEGF effects on integrin expression and activation in human brain microvascular endothelial cells (HBMECs). Using human cDNA arrays and ribonuclease (RNase) protection assays, we observed that VEGF up-regulated the mRNA expression of alpha(6) integrin in HBMECs. VEGF significantly increased alpha(6)beta(1) integrin expression, but not alpha(6)beta(4) integrin expression in these cells. Specific down-regulation of alpha(6) integrin expression by small interfering RNA (siRNA) oligonucleotides inhibited both the capillary morphogenesis of HBMECs and their adhesion and migration. Additionally, VEGF treatment resulted in activation of alpha(6)beta(1) integrins in HBMECs. Functional blocking of alpha(6) integrin with its specific antibody inhibited the VEGF-induced adhesion and migration as well as in vivo angiogenesis, and markedly suppressed tumor angiogenesis and breast carcinoma growth in vivo. Thus, VEGF can modulate angiogenesis via increased expression and activation of alpha(6)beta(1) integrins, which may promote VEGF-driven tumor angiogenesis in vivo.     

Infusion of a Lipid Emulsion Modulates AMPK and Related Proteins in Rat Liver,Muscle, and Adipose Tissues

The primary objective of this study was to investigate the impact of lipid oversupply on the AMPK pathway in skeletal muscle, liver, and adipose tissue. Male Wistar rats were infused with lipid emulsion (LE) or phosphate‐buffered saline for 5 h/day for 6 days. Muscles exposed to LE for 6 days exhibited increased AMPK and acetyl‐CoA carboxylase (ACC) phosphorylation, along with a greater association between AMPK and Ca²⁺/calmodulin‐dependent protein kinase kinase (CaMKK). No differences in muscle protein phosphatase 2C (PP2C) activity, LKB1 phosphorylation or AMPK and LKB1 association were observed. Muscle ACCβ, and adiponectin receptor 1 (AdipoR1) mRNA levels and PPARγ‐co‐activator 1α (PGC1α) protein levels were also increased in LE‐treated rats. In contrast, AMPK and ACC phosphorylation decreased and PP2C activity increased in rat livers exposed to LE. Hepatic mRNA levels of ACCα, PPARα, AdipoR1, AdipoR2, and sterol regulatory element–binding protein‐1c (SREBP1c) were also reduced after LE infusion. In adipose tissue, there was no significant alteration in AMPK or ACC phosphorylation. These results demonstrate that following lipid oversupply the AMPK pathway was enhanced in rat skeletal muscle while diminished in the liver and was unchanged in adipose tissue. CaMKK in skeletal muscle and PP2C in the liver, at least in part, appear to mediate these alterations. Alterations in AMPK pathway in the liver induced metabolic defects associated with lipid oversupply.     

Comparative computational analysis of prion proteins reveals two fragments with unusual structural properties and a pattern of increase in hydrophobicity associated with disease-promoting mutations

Prion diseases are a group of neurodegenerative disorders associated with conversion of a normal prion protein, PrPC, into a pathogenic conformation, PrPSc. The PrPSc is thought to promote the conversion of PrPC. The structure and stability of PrPC are well characterized, whereas little is known about the structure of PrPSc, what parts of PrPC undergo conformational transition, or how mutations facilitate this transition. We use a computational knowledge-based approach to analyze the intrinsic structural propensities of the C-terminal domain of PrP and gain insights into possible mechanisms of structural conversion. We compare the properties of PrP sequences to those of a PrP paralog, Doppel, and to the distributions of structural propensities observed in known protein structures from the Protein Data Bank. We show that the prion protein contains at least two sequence fragments with highly unusual intrinsic propensities, PrP(114-125) and helix B. No segments with unusual properties were found in Doppel protein, which is topologically identical to PrP but does not undergo structural rearrangements. Known disease-promoting PrP mutations form a statistically significant cluster in the region comprising helices B and C. Due to their unusual properties, PrP(114-125) and the C terminus of helix B may be considered as primary candidates for sites involved in conformational transition from PrPC to PrPSc. The results of our study also show that most PrP mutations associated with neurodegenerative disorders increase local hydrophobicity. We suggest that the observed increase in hydrophobicity may facilitate PrP-to-PrP or/and PrP-to-cofactor interactions, and thus promote structural conversion.     

HIV-1 Tat-mediated apoptosis in human brain microvascular endothelial cells

The integrity of the blood-brain barrier (BBB) is critical for normal brain function. Neuropathological abnormalities in AIDS patients have been associated with perivascular HIV-infected macrophages, gliosis, and abnormalities in the permeability of the BBB. The processes by which HIV causes these pathological conditions are not well understood. To characterize the mechanism by which HIV-1 Tat protein modulates human brain microvascular endothelial cell (HBMEC) functions, we studied the effects of HIV-1 Tat in modulating HBMEC apoptosis and permeability. Treatment of HBMEC with HIV-1 Tat led to Flk-1/KDR and Flt-4 receptor activation and the release of NO. The protein levels of endothelial NO synthase (NOS) and inducible NOS were increased by HIV-1 Tat stimulation. Importantly, HIV-1 Tat caused apoptosis of HBMEC, as evidenced by changes in the cleavage of poly(A)DP-ribose polymerase, DNA laddering, and incorporation of fluorescein into the nicked chromosomal DNA (TUNEL assay). HIV-1 Tat-mediated apoptosis in HBMEC was significantly inhibited in the presence of N-nitro-L-arginine methyl ester (an inhibitor of NOS) and wortmannin (a phosphoinositol 3-kinase inhibitor). Furthermore, HIV-1 Tat treatment significantly increased HBMEC permeability, and pretreatment with both N-nitro-L-arginine methyl ester and wortmannin inhibited the Tat-induced permeability. Taken together, these results indicate that dysregulated production of NO by HIV-1 Tat plays a pivotal role in brain endothelial injury, resulting in the irreversible loss of BBB integrity, which may lead to enhanced infiltration of virus-carrying cells across the BBB.     

Outcome of patients with toxic epidermal necrolysis syndrome revisited

Toxic epidermal necrolysis syndrome is an uncommon, acute, life-threatening, medication-induced disorder with a reported mortality rate of 20 to 60 percent. Different variables have been identified as risk factors. The extent to which these variables, when combined, affect the mortality and outcome in toxic epidermal necrolysis syndrome patients has not yet been reliably defined. Because of the high mortality rate, the logistic analysis of studied variables was performed to see whether a prognostic algorithm could be developed to aid the management of these patients. Thus, a retrospective review of 56 consecutive toxic epidermal necrolysis syndrome patients treated over a period of 13 years was undertaken in the authors' burn center. The demographics included age, sex, race, and total body surface area involved. The other variables studied were comorbidities, sepsis, steroid administration, and the interval between onset of rash and burn center admission. Data were subjected to Fisher's exact test and logistic analysis. Thirty-six patients (64.3 percent) were alive and 20 (35.7 percent) died. Univariate analysis indicated that the male/female ratio was 12:24 for survivors and 9:11 for nonsurvivors (p = 0.4). The white/nonwhite ratio was 80 percent for survivors and 54 percent for nonsurvivors (p = 0.58). The median age was 48.4 +/- 22.8 years (survivors, 41.7 +/- 22.0; nonsurvivors, 60.5 +/- 19.5; p = 0.002). Total body surface area involvement for survivors was 56.9 +/- 32 and 77.7 +/- 21 for nonsurvivors (p = 0.005). The presence of one or more comorbidities between the two groups differed (53 percent survivors and 90 percent nonsurvivors, p = 0.007), indicating eight times higher odds of dying in their presence. The average time between the onset of symptoms and admission to the burn unit was 5.25 +/- 3.4 days for survivors and 7.15 +/- 4.5 days for nonsurvivors (p = 0.08). The presence of sepsis (19.4 percent survivors, 95 percent nonsurvivors, p < 0.001) decreased odds for survival by a factor of 79. Steroids given as a single dose or multiple doses before the patient's transfer to the burn unit were not significantly associated with death (44 percent survivors, 65 percent nonsurvivors, p = 0.14). A multivariate logistic regression model yielded odds ratios of 1.11 (95 percent confidence interval, 1.03 to 1.19) for age in years, 304 (95 percent confidence interval, 8.83 to 10,400) for the presence of sepsis, and 1.03 (95 percent confidence interval, 0.99 to 1.08) for body surface area in percent. All those entering the burn unit with sepsis died. Equivalently, no survivors had sepsis before admission to the burn unit, whereas 55 percent of nonsurvivors had sepsis before admission and 40 percent developed sepsis after admission. When investigating the effect of age and sepsis, no patients over age 60 ever having sepsis survived, whereas all those who were under 60 and without sepsis survived. Likewise, all patients whose age was over 60 and whose total body surface area involved was over 60 percent died. The main factors contributing to the mortality from toxic epidermal necrolysis syndrome, when considering covariates separately, are the presence of sepsis at any time (odds ratio, 79), the presence of comorbidities (odds ratio, 8.05), age, and total body surface area, whereas multivariate models suggested age (odds ratio per year of additional age, 1.11), total body surface area (odds ratio per additional percent of body surface area, 1.03), and the presence of sepsis (odds ratio, 304). By using the actual coefficients in the logistic model, the log odds that the patient will die as the result of his or her condition can be summarized in the following formula: -11.5 + (10 percent of the patient's age + 3 percent of total body surface area + 5.75 if sepsis is present). The awareness of the importance of these covariates, and their early recognition as risk factors, should offer a focused approach to the patients' management and improve their outcome.     

Increasing progesterone secretion and 3β-hydroxysteroid dehydrogenase activity of human cumulus cells and granulosa-lutein cells concurrent with successful fertilization of the corresponding oocyte

In many studies it has been documented that the induction of multiple follicular growth in humans results in an asynchrony between the degree of cumulus mucification, oocyte meiotic maturation, fertilizability, and follicular cell progesterone (P₄) secretion. The present study was carried out on oocytes enclosed in fully mucified cumulus. Thus, oocyte fertilizability was correlated to human cumulus cell (hCC) and human granulosa-lutein (G-L) cell competence for P₄ secretion in culture. In the G-L cells, P₄ secretion and percentage of cells manifesting 3β-hydroxysteroid dehydrogenase (3β-HSD) activity increased concurrently with the period of culture. In the hCC, however, P₄ secretion decreased concurrently with elongation of the culture period, whereas the percentage of 3β-HSD-positive cells increased. In hCC corresponding to the fertilized oocytes, P₄ accumulation in culture medium was 1.9-fold (P < 0.001) and 1.6-fold (P < 0.02) higher on days 0–3 and 3–5 of culture, respectively, as compared to P₄ accumulation in hCC of unfertilized oocytes. Also, in hCC corresponding to the fertilized oocytes, the degree of 3β-HSD activity was found to be significantly higher shortly after aspiration and after either 3 or 5 days, compared to hCC of unfertilized oocytes. In the G-L cells pooled from all follicles yielding mature cumulus-oocyte complexes, P₄ accumulation and percentage of 3β-HSD-positive cells increased concurrently with the increase in percentage of fertilized eggs of each individual woman. These results indicate that in stimulated cycles, follicles yielding mature cumulus-oocyte complex, oocyte fertilizability, and G-L cell or hCC competence for P₄ secretion are correlated and synchronous.     

Inhibition of protein secretion and protein kinase activity in the locust fat body by diamide (Azodicarboxylic acid-bis-dimethylamide)

Protein secretion from locust fat body incubated in vitro is instantaneously halted in the presence of diamide (azodicarboxylic acid-bis-dimethylamide). Independent inhibition of amino acid uptake, protein synthesis (verified in cell-free systems), and protein secretion is demonstrated. Diamide inhibits cyclic AMP- and cyclic GMP-dependent protein kinase activity in locust fat body.