Biodegradable poly(ester urethane) urea scaffolds for tissue engineering: Interaction with osteoblast-like MG-63 cells

Porous three-dimensional scaffolds with potential for application as cancellous bone graft substitutes were prepared from aliphatic segmented poly(ester urethane) urea using the phase-inverse technique. Proton nuclear magnetic resonance, size-exclusion chromatography, electron spectroscopy for chemical analysis, secondary ion mass spectrometry, infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, computed tomography and mechanical tests were carried out, to characterize the scaffolds’ physicochemical properties. Human osteosarcoma MG-63 cells were seeded into the scaffolds for 1, 2, 3 and 4 weeks to evaluate their potential to support attachment, growth and proliferation of osteogenic cells. The scaffold–cell interaction was assessed by analysis of DNA content, total protein amount, alkaline phosphatase activity and WST-1 assay. The scaffolds supported cell attachment, growth and proliferation over the whole culture period of 4 weeks (DNA, total protein amount). There was, however, a reduction in the WST-1 assay values at 4 weeks, which might suggest a reduction in the rate of cell proliferation at this time.     

Blood-brain barrier permeability precedes senile plaque formation in an Alzheimer disease model

OBJECTIVE: To establish the generality of cerebrovascular pathology frequently observed with Alzheimer disease, we have assessed blood-brain barrier (BBB) integrity using the Alzheimer disease model Tg2576 mice in which cognitive deficits and neuritic plaque formation develop around 10-12 months of age. METHODS: We assessed BBB integrity using well-established methods involving albumin and Evans blue uptake and introduce the use of a novel perfusion protocol using succinimidyl ester of carboxyfluorescein diacetate. RESULTS: BBB permeability is increased in the cerebral cortex of 10-month-old Tg2576 mice preceding Alzheimer disease pathology presentation. Furthermore, when compared with their nontransgenic littermates, 4-month-old Tg2576 mice exhibit compromised BBB integrity in some areas of the cerebral cortex. An age-related increase in albumin uptake by the brains of Tg2576 mice, compared with nontransgenic mice, was also observed. These findings were supported by quantitative Evans blue analysis (p = 0.07, two-way analysis of variance). CONCLUSION: A breakdown of BBB was evident in young 4- to 10-month-old Tg2576 mice. Compromised barrier function could explain the mechanisms of Abeta entry into the brain observed in experimental Alzheimer disease vaccination models. Such structural changes to the BBB caused by elevated Abeta could play a central role in Alzheimer disease development and might define an early point of intervention for designing effective therapy against the disease.     

Diethyldithiocarbamate Methyl Ester Sulfoxide, an Inhibitor of Rat Liver Mitochondrial Low Km Aldehyde Dehydrogenase and Putative Metabolite of Disulfiram

S-methyl N,N -diethylthiolcarbamate sulfoxide (DETC-MeSO) is a potent inhibitor of rat liver mitochondrial low K _m aldehyde dehydrogenase (ALDH₂) both in vivo and in vitro, and has been proposed to be the metabolite responsible for ALDH₂ inhibition by disulfiram. Diethyldithiocarbamate methyl ester (DDTC-Me), a key intermediate in the metabolism of disulfiram, has been shown to be bioactivated by microsomal monooxygenases to diethyldithiocarbamate methyl ester sulfoxide (DDTC-Me sulfoxide). Studies were conducted to determine if DDTC-Me sulfoxide was also an active metabolite of disulfiram and inhibitor of ALDH₂. DDTC-Me sulfoxide inhibited ALDH₂ in vitro with an IC₅₀ of 10 μm, and in vivo with an ID₅₀ of 31 mg/kg (170 μmol/kg). Maximal ALDH₂ inhibition in vivo was observed 8 hr after the administration of 45.2 mg/kg DDTC-Me sulfoxide, with ALDH₂ activity returning to control levels after 48 hr. Although DDTC-Me sulfoxide inhibited ALDH₂ in vivo, DDTC-Me sulfoxide was not detected in plasma from rats treated with either disulfiram (75 mg/kg), DDTC-Me (122.25 mg/kg), or DDTC-Me sulfoxide (45.2 mg/kg). However, DDTC-Me and S -methyl N,N -diethylthiolcarbamate (DETC-Me) were detected in plasma from rats treated with DDTC-Me sulfoxide. In rats treated with DDTC-Me sulfoxide and challenged with ethanol, a small increase of ∼9 μm in blood acetaldehyde and an inconsistent drop in blood pressure was observed. In conclusion, DDTC-Me sulfoxide inhibited ALDH₂ in vitro and in vivo, was less potent than DETC- MeSO, and was not detected after disulfiram administration.     

CETP is a determinant of serum LDL-cholesterol but not HDL-cholesterol in healthy Japanese

Cholesteryl ester transfer protein (CETP) is one of the factors that regulate plasma levels of HDL-cholesterol. To identify the factors that may regulate CETP activity, and to determine to what extent CETP is correlated with physiologic concentrations of lipoprotein, we performed an epidemiologic study in 586 healthy volunteers (317 males and 269 females, mean age 52.2 ± 10.9 years). CETP activity in these subjects was 192.96 ± 48.73 (mean ± S.D.) nmol/ml/h and distributed to a wide range (60–450 nmol/ml/h). Using multiple regression analysis, we found significant positive correlations between CETP activity and LDL-cholesterol (P < 0.03), apolipoprotein (apo) E (P < 0.005) and LCAT activity (P < 0.001). CETP activities showed significant negative correlation with apo A-I (P < 0.03). However, CETP activity showed no significant correlation either with HDL cholesterol or with apo B. One-way layout analysis of variance showed that alcohol drinking and cigarette smoking significantly reduced CETP activity, but there was no significant association between CETP activity and body mass index. Although CETP activities were significantly higher in females than in males (P < 0.001), multiple regression analysis showed no correlation between CETP activity and age in either the males or the females. Our results suggest that CETP activity regulates the concentration of apo A-I and LDL-cholesterol, and that such activity may be influenced by gender, alcohol consumption and cigarette smoking.     

饮料中邻苯二甲酸酯的分散式液液微萃取-高效液相色谱测定法

目的建立饮料中3种邻苯二甲酸酯(PAEs)的分散式液液微萃取-高效液相色谱测定法。方法以甲醇为分散剂,以四氯乙烯为萃取剂,饮料样品中PAEs经分散式液液微萃取(DLLME)富集,采用HITACHI-C18色谱柱,乙腈和水梯度洗脱分离后在203 nm检测。结果邻苯二甲酸丁卞酯(BBP)的线性范围为0.500~400.0 ng/ml(r=0.999 8),邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二异辛酯(DEHP)的线性范围均为0.250~200.0 ng/ml(r=0.999 3),检出限均为0.05 ng/ml,回收率为85.3%~103.3%,相对标准偏差为2.4%~5.6%。结论该方法灵敏度、准确度高,适用于饮料样品中PAEs的检测。     

Lipoprotein(a): Pathophysiology,measurement, indication and treatment in cardiovascular disease. A consensus statement from the Nouvelle Société Francophone d’Athérosclérose (NSFA)

Central Illustration. Pathophysiological pathways providing a causal link between high plasma concentrations of lipoprotein(a) (Lp(a)) and atherosclerotic vascular disease and aortic valve stenosis (AVS). Clinical outcomes are related to accelerated atherosclerosis complicated by atherothrombosis (myocardial infarction, stroke), peripheral artery disease (PAD) or aortic valve replacement (AVR) caused by valve calcification and aortic stenosis. Apo(a): apolipoprotein(a); LDL: low-density lipoprotein; OxPL: oxidized phospholipids; NSFA: Nouvelle Société Francophone d’Athérosclérose; SP: serine-protease domain; V: plasminogen kringle V (reproduced with permission).

     

The role of protein kinase C in insulin biosynthesis

Activation of protein kinase C (PKC) by the phorbol ester 4-phorbol myristate acetate (4-PMA) stimulated (pro)insulin biosynthesis in collagenase-isolated rat islets of Langerhans, as assessed by measuring the incorporation of [³⁵S]cysteine into proinsulin and insulin after fractionation by high performance liquid chromatography. The stimulatory effects of 4-PMA were observed at a substimulatory concentration of glucose (2 mM) but were not additive to the stimulatory effects of 20 mM glucose on insulin biosynthesis. Prolonged exposure to 4-PMA caused a marked down-regulation of PKC activity in islets. PKC-depleted islets showed a much reduced biosynthetic response to 20 mM glucose, but this was caused, at least in part, by an enhanced basal rate of (pro)insulin synthesis. These elevations in the basal rate of insulin synthesis were not secondary to an inerease in the amount of preproinsulin mRNA in PKC-depleted islets since Northern blot analysis showed that prolonged exposure to 4-PMA, and the subsequent loss of PKC activity, did not detectably alter basal levels of preproinsulin mRNA. These results suggest that the activation of PKC stimulates (pro)insulin synthesis in rat islets by enhancing translation of existing preproinsulin mRNA, and that this may play some part in the biosynthetic responses of -cells to glucose.     

Restricted effect of formycin A and non-glucidic nutrients upon insulin release in islets from rats with hereditary or acquired non-insulin-dependent diabetes

Pancreatic islets isolated from control rats, Goto-Kakizaki rats and adult rats that were injected with streptozotocin during the neonatal period were incubated for two successive periods of 90 min each in the presence ofd-glucose (11.1 mM) with or without formycin A (1.0 mM), and in the presence of the dimethyl ester of succinic acid (SAD, 10.0 mM) with or without palmitate (1.0 mM). Although formycin A augmented glucose-stimulated insulin release in both control and diabetic rats, it failed to compensate for the impaired secretory response tod-glucose in the latter animals. Likewise, non-glucidic nutrients such as SAD and/or palmitate failed to display a more efficient insulinotropic action, relative to basal insulin output, in diabetic than control rats. These results indicate that both formycin A and non-glucidic nutrients are unable, through their immediate insulinotropic action, to restore a normal output of insulin in islets of animals with inherited or acquired non-insulin-dependent diabetes.