Proanthocyanidin: a natural crosslinking reagent for stabilizing collagen matrices

While attempting to find a suitable crosslinking reagent for biopolymers, a naturally occurring proanthocyanidin (PA) obtained from grape seeds was selected to fix biological tissues. The cytotoxicity and crosslinking rate, reflected by the in vitro and in vivo degradation of fixed matrices has been studied. The shrinkage temperature of the fixed bovine pericardium increased from 66 to 86 degrees C. A cytotoxicity assay using fibroblast cultures revealed that PA is approximately 120 times less toxic than glutaraldehyde (GA), a currently used tissue stabilizer. In vitro degradation studies showed that fixed tissue was resistant to digestion by bacterial collagenase. Crosslinks between PA and tissues can be stabilized by decreasing the dielectric constant of the solution during storage. After subcutaneous implantation for periods ranging between 3 and 6 weeks, we found no apparent degradation of the GA- or PA-fixed tissues, whereas fresh tissue controls rapidly disintegrated. Beyond 6 weeks PA crosslinks began to degrade. More fibroblasts migrated and proliferated inside the PA-fixed implants compared with GA counterparts. Tissues crosslinked with PA manifested an enhanced collagen expression and deposition and did not calcify after implantation. GA, on the other hand, even after thorough rinsing continued to be cytotoxic, inhibited collagen synthesis and encouraged dystrophic calcification. Collagen matrices crosslinked with PA are expected to be of value in the design of matrices that will encourage cell ingrowth and proliferation, which are temporary in nature, and that are intended to regenerate or replace missing tissues, which can delay the biogradation of collagen. As such they should be of significant value in the emerging field of tissue engineering.     

Attenuated amplitude of circadian and sleep-dependent modulation of electroencephalographic sleep spindle characteristics in elderly human subjects

The low density lipoprotein receptor-related protein (LRP) gene is a candidate gene for Alzheimer's disease (AD) due to its role as a receptor for apolipoprotein E (apoE), a major genetic risk factor for late-onset familial and sporadic AD. Recently, several studies have reported a correlation between a polymorphism (C766T) in exon 3 of LRP and AD. We examined this polymorphism in a Caucasian population of 225 neuropathologically confirmed cases with AD and 187 elderly cases without any AD neuropathological changes. We found that the exon 3 LRP C/C genotype was slightly but not significantly higher in the AD group when compared to the control group. A meta-analysis of previous studies revealed only a weak correlation of this polymorphism with AD (odds ratio 1.34, [95% CI 1.16-1.54], P < 0.0001). These data indicate that the polymorphism in exon 3 of LRP is only a minor risk factor for AD and that another locus on chromosome 12 is likely responsible for the associations observed in other studies.     

Viral load responses to HAART is an independent predictor of a new AIDS event in late stage HIV infected patients: prospective cohort study

Background  

A sizeable number of HIV-infected patients receiving HAART do not maintain prolonged virologic suppression. We evaluated long-term HIV viral load (VL) responses to HAART as a risk factor for AIDS events (AE) that is independent of CD4 responses.     

一种可生物降解温度敏感型聚乙二醇-聚己内酯-聚乙二醇水凝胶的合成和表征

合成了一系列分子量较低的聚乙二醇．聚己内酯-聚乙二醇（Poly（ethylene glycol）-Polycaprolactone-Poly（ethylene glycol），PEG-PCL—PEG）三嵌段共聚物。分别采用FTIR和1H—NMR对其结构进行了表征。所合成的PEG-PCL-PEG共聚物具有良好的水溶性，当水溶液浓度高于临界凝胶浓度（Critical gel concentration，CGC）时，随着温度的变化聚合物水溶液会呈现特有的凝胶-溶胶转变。研究了共聚物亲水疏水链段的比例和长度，以及热历史等对凝胶-溶胶转变行为的影响。通过调节上述条件，可以在一定程度上拓宽凝胶-溶胶转变温度范围，有助于PEG—PCL-PEG水凝胶在可注射药物控制释放系统等方面的应用。     

Retinal dehydrogenase-2 is inhibited by compounds that induce congenital diaphragmatic hernias in rodents

Currently, the etiology of the serious developmental anomaly congenital diaphragmatic hernia (CDH) is unknown. We have used an animal model of CDH to address this issue. We characterized four separate teratogens that produced diaphragmatic defects in embryonic rats that are similar to those in infants with CDH. We then tested the hypothesis that all these agents share the common mechanism of perturbing the retinoid-signaling pathway. Specifically, inhibition of retinal dehydrogenase-2 (RALDH2), a key enzyme necessary for the production of retinoic acid and that is expressed in the developing diaphragm, was assayed by measuring retinoic acid production in cytosolic extracts from an oligodendrocyte cell line. The following compounds all induce posterolateral defects in the rat diaphragm; nitrofen, 4-biphenyl carboxylic acid, bisdiamine, and SB-210661. Importantly, we demonstrate that they all share the common mechanism of inhibiting RALDH2. These data provide an important component of mounting evidence suggesting that the retinoid system warrants consideration in future studies of the etiology of CDH.     

Effects of ammonium metavanadate treatment upon macrophage glutathione redox cycle activity, superoxide production, and intracellular glutathione status

Female B6C3F1 mice were given intraperitoneal injections of ammonium metavanadate (2.5 or 10 mg V/Kg), ammonium chloride, or sodium phosphate buffer every 3 days for 6 weeks. Resident peritoneal macrophages were harvested, lysed by freeze-thawing, and the resulting cytolysate was assayed for total protein content and enzyme activities of glutathione reductase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase. In addition, peritoneal macrophages were assayed for superoxide production using nitroblue tetrazolium reduction, as well as for intracellular levels of oxidized and reduced glutathione. Exposure of mice to vanadium resulted in a dose-trend depression in the three macrophage enzyme activities as compared with the controls. Vanadium treatment resulted in a similar decrease in the production of superoxide anion, and an increase in levels of oxidized glutathione; however, the total glutathione pool (reduced plus oxidized forms) was not affected.     

Immunochemical data suggesting a pattern for the evolution of human placental alkaline phosphatase

Hyperimmune absorbed rabbit antisera which were reactive with epitopes specific for individual variants of human placental alkaline phosphatase were tested for their reactivity with primate placental alkaline phosphatases. Using the three epitope-specific reactivities defined previously, we found that: epitope I is present in the S-, D- and I-variants of human placental phosphatase, and in the chimpanzee and pygmy chimpanzee placentae; epitope II is present in the F- and 17-variants, and in the Nagao isoenzyme of human placental alkaline phosphatase, and in some orangutan placentae and all spider monkey placentae tested; epitope III is present in the F- and 17-variants, and the Nagao isoenzyme of human placental alkaline phosphatase, and in all the spider monkey placentae and the single squirrel monkey placenta examined. The binding assay was complemented by a competitive radioimmunoassay, which confirmed that the spider monkey placental samples were binding to the same antibody population which bound the human enzymes. The presence of epitopes characteristic of rare human placental phosphatase variants in these remote primate relatives suggests that the rare variants in the current human population have been present during the entire course of evolution. The presence of both epitopes characteristic of the Nagao isoenzyme in spider monkeys suggests that this variant isoenzyme is closely related to the enzyme present in the primate placenta at the time of species divergence (humans and New World monkeys). A hypothetical scheme for this divergence is proposed.     

The calpain system

The calpain system originally comprised three molecules: two Ca2+-dependent proteases, mu-calpain and m-calpain, and a third polypeptide, calpastatin, whose only known function is to inhibit the two calpains. Both mu- and m-calpain are heterodimers containing an identical 28-kDa subunit and an 80-kDa subunit that shares 55-65% sequence homology between the two proteases. The crystallographic structure of m-calpain reveals six "domains" in the 80-kDa subunit: 1). a 19-amino acid NH2-terminal sequence; 2). and 3). two domains that constitute the active site, IIa and IIb; 4). domain III; 5). an 18-amino acid extended sequence linking domain III to domain IV; and 6). domain IV, which resembles the penta EF-hand family of polypeptides. The single calpastatin gene can produce eight or more calpastatin polypeptides ranging from 17 to 85 kDa by use of different promoters and alternative splicing events. The physiological significance of these different calpastatins is unclear, although all bind to three different places on the calpain molecule; binding to at least two of the sites is Ca2+ dependent. Since 1989, cDNA cloning has identified 12 additional mRNAs in mammals that encode polypeptides homologous to domains IIa and IIb of the 80-kDa subunit of mu- and m-calpain, and calpain-like mRNAs have been identified in other organisms. The molecules encoded by these mRNAs have not been isolated, so little is known about their properties. How calpain activity is regulated in cells is still unclear, but the calpains ostensibly participate in a variety of cellular processes including remodeling of cytoskeletal/membrane attachments, different signal transduction pathways, and apoptosis. Deregulated calpain activity following loss of Ca2+ homeostasis results in tissue damage in response to events such as myocardial infarcts, stroke, and brain trauma.     

Emergency department visits for asthma: the role of frequent symptoms and delay in care.

BACKGROUND: Use of the emergency department (ED) for asthma care is a costly form of health care that is largely preventable. However, little is known about how to reduce the number of people using the ED for asthma care. OBJECTIVE: To identify modifiable factors related to ED visits for asthma among a diverse nonelderly adult population. METHODS: This study used cross-sectional data from the 2001 California Health Interview Survey. A total of 4,359 adult respondents ages 18 to 64 years who reported being diagnosed as having asthma and experiencing symptoms in the past year were included. Any ED visits due to asthma in the previous 12 months among all nonelderly respondents with asthma, with stratification by those with daily or weekly symptoms and with less frequent symptoms, were examined. RESULTS: Adults with daily or weekly asthma symptoms, with fair or poor health status, and who delayed care for asthma because of cost or insurance issues were more likely to visit the ED for asthma. Stratification of the study population into those with daily or weekly symptoms and those with less frequent symptoms revealed that delay in care due to cost or insurance issues and fair or poor health status remained significant for both groups. Latinos and women were more likely to visit the ED in the severe asthma group, whereas Asian, African American, and uninsured adults were more likely to visit the ED in the group with less severe asthma. CONCLUSIONS: Results suggest that to prevent ED visits for asthma, it is important to control asthma symptoms. However, it is equally if not more important to reduce delays in receiving asthma care.