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At least 199 records · Page 11Linked to original sources
PubMed2005

Engineering of volume-stable adipose tissues.

Autologous adipose tissues have been clinically used for augmentation of soft tissues lost due to mastectomy or lumpectomy in plastic and reconstructive surgery. However, this therapy has problems of absorption and subsequent volume loss of the implanted adipose tissues. In this study, volume-stable adipose tissues were engineered in vivo using mechanical support structures fabricated from biodegradable synthetic polymers. Dome-shaped mechanical support structures were fabricated by reinforcing poly(glycolic acid) fiber-based matrices with poly(L-lactic acid). The support structures were placed into subcutaneous pockets of athymic mice, and human preadipocytes suspended in fibrin matrix were injected into the space under the support structures (group I). Injection of either fibrin matrix without preadipocytes under the support structures (group II) or fibrin matrix containing preadipocytes into subcutaneous spaces with no support structures (group III) served as controls. Six weeks after implantation, the original implant volume was maintained approximately in groups I and II, whereas, group III showed significant implant shrinkage. The compressive modulus of the mechanical support structures did not change significantly over 6-week incubation in phosphate-buffered saline at 37 degrees C. Histological analyses of the implants showed regeneration of adipose tissues in group I. In contrast, groups II and III did not show extensive adipose tissue formation. This study demonstrates that volume-stable adipose tissues can be engineered in vivo using mechanical support structures. This technique offers the potential for augmentation of adipose tissues with volume conservation.

Adipocytes↗
PubMed1984

Kin groups and trait groups: population structure and epidemic disease selection.

A Monte Carlo simulation based on the population structure of a small-scale human population, the Semai Senoi of Malaysia, has been developed to study the combined effects of group, kin, and individual selection. The population structure resembles D.S. Wilson's structured deme model in that local breeding populations (Semai settlements) are subdivided into trait groups (hamlets) that may be kin-structured and are not themselves demes. Additionally, settlement breeding populations are connected by two-dimensional stepping-stone migration approaching 30% per generation. Group and kin-structured group selection occur among hamlets the survivors of which then disperse to breed within the settlement population. Genetic drift is modeled by the process of hamlet formation; individual selection as a deterministic process, and stepping-stone migration as either random or kin-structured migrant groups. The mechanism for group selection is epidemics of infectious disease that can wipe out small hamlets particularly if most adults become sick and social life collapses. Genetic resistance to a disease is an individual attribute; however, hamlet groups with several resistant adults are less likely to disintegrate and experience high social mortality. A specific human gene, hemoglobin E, which confers resistance to malaria, is studied as an example of the process. The results of the simulations show that high genetic variance among hamlet groups may be generated by moderate degrees of kin-structuring. This strong microdifferentiation provides the potential for group selection. The effect of group selection in this case is rapid increase in gene frequencies among the total set of populations. In fact, group selection in concert with individual selection produced a faster rate of gene frequency increase among a set of 25 populations than the rate within a single unstructured population subject to deterministic individual selection. Such rapid evolution with plausible rates of extinction, individual selection, and migration and a population structure realistic in its general form, has implications for specific human polymorphisms such as hemoglobin variants and for the more general problem of the tempo of evolution as well.

Communicable Diseases↗
PubMed2005

Population structure of group B streptococcus from a low-incidence region for invasive neonatal disease.

The population structure of group B streptococcus (GBS) from a low-incidence region for invasive neonatal disease (Israel) was investigated using multilocus genotype data. The strain collection consisted of isolates from maternal carriage (n=104) and invasive neonatal disease (n=50), resolving into 46 sequence types. The most prevalent sequence types were ST-1 (17.5 %), ST-19 (10.4 %), ST-17 (9.7 %), ST-22 (8.4 %) and ST-23 (6.5 %). Serotype III was the most common, accounting for 29.2 % of the isolates. None of the serotypes was significantly associated with invasive neonatal disease. burst analysis resolved the 46 sequence types into seven lineages (clonal complexes), from which only lineage ST-17, expressing serotype III only, was significantly associated with invasive neonatal disease. Lineage ST-22 expressed mainly serotype II, and was significantly associated with carriage. The distribution of the various sequence types and lineages, and the association of lineage ST-17 with invasive disease, are consistent with the results of analyses from a global GBS isolate collection. These findings could imply that the global variation in disease incidence is independent of the circulating GBS populations, and may be more affected by other risk factors for invasive GBS disease, or by different prevention strategies.

Carrier State↗
PubMed1992

Characterization of the Streptococcus adjacens group antigen structure.

Serological classification of bacteria requires the presence of an antigen unique to the organism of interest. Streptococci are serologically differentiated by group antigens, many of which are carbohydrates, although some are amphiphiles. This report describes the chemical characterization of the Streptococcus adjacens group antigen structure. Previous studies demonstrated that the amphiphile contained phosphorus, ribitol, galactose, galactosamine, alanine, and fatty acids. Phosphodiester bonds present in the purified group antigen were identified as part of a poly(ribitol phosphate), since ribitol phosphate was the only organic phosphate detected after acid hydrolysis. Hydrofluoric acid cleavage of the phosphodiester bonds generated oligosaccharide repeating units. Gas chromatography-mass spectrometric analysis of the methylated, acetylated oligosaccharide suggested that the repeating unit is a trisaccharide of Galp beta 1-3Galp beta 1-4GalNac with N-acetylgalactosamine attached in beta-linkage to either the number two or the number four carbon of ribitol. The lipid- and carbohydrate-substituted poly(ribitol phosphate) of the S. adjacens group antigen therefore is a unique amphiphile structure, differing in its repeating-unit structure from the polyglycerophosphate structure of the more common gram-positive amphiphile lipoteichoic acid.

Alanine↗
PubMed2004

Red blood cell blood group antigens: structure and function.

Red blood cell (RBC) blood group antigens are polymorphic, inherited, carbohydrate or protein structures located on the extracellular surface of the RBC membrane. They contribute to the architecture of the RBC membrane, and their individual function(s) are being slowly revealed. The biological qualities assigned to these RBC membrane structures are based on observed physiological alteration in RBCs that lack the component, by documenting similarities in its protein sequence (predicted from the nucleotide sequence of the gene) to proteins of known function and by extrapolation to identified functional homologues in other cells. The varied roles of RBC antigens include membrane structural integrity, the transport of molecules through the membrane, as receptors for extracellular ligands, adhesion molecules, enzymes, complement components and regulators, and in glycocalyx formation.

Blood Group Antigens↗
PubMed2001

Synthesis of photo- and electroactive stilbenoid dendrimers carrying dibutylamino peripheral groups.

[structure: see text]. A novel convergent synthetic route for the preparation of functionalized and fluorescent stilbenoid dendrons built on the 1,3,5-benzene core and endowed with a periphery of dibutylamino groups has been developed. Long alkyl chains have been incorporated on the peripheral amino moieties to increase the solubility of the final products. Good donor ability of the new dendrimers has been observed by cyclic voltammetry measurements as a result of the presence of the peripheral dibutylaniline moieties.

Journal Article↗
PubMed2000

Therapeutic studies and arterial stiffness in hypertension: recommendations of the European Society of Hypertension. The Clinical Committee of Arterial Structure and Function. Working Group on Vascular Structure and Function of the European Society of Hypertension.

BACKGROUND: Increased pulse pressure and arterial stiffness are identified as predictors of cardiovascular risk in older hypertensive populations, particularly that of myocardial infarction. Because increased pulse pressure involves an increase in systolic (SBP) and a decrease in diastolic blood pressure (DBP), and because the former promotes cardiac hypertrophy and the latter alters coronary perfusion, a drug regimen reducing pulse pressure and decreasing arterial stiffness might further reduce cardiovascular risk. Under conventional treatment, normalization of DBP (< or = 90 mmHg) is not consistently associated with normalization of SBP (< or = 140 mmHg). THERAPEUTIC DESIGNS: In individuals older than 50 years, the goal of antihypertensive treatment should be, not only to decrease mean blood pressure (to less than 100 mmHg), but also to decrease pulse pressure (to less than 50 mmHg). Using appropriate pharmacological tools, trials should test whether an active decrease in arterial stiffness might produce an attenuation of the age-related increase in SBP and decrease in DBP, thus delaying the age-related increase in pulse pressure and decreasing further cardiovascular risk. This procedure requires concomitant non-invasive evaluations of aortic stiffness. CONCLUSION: The studies that are required in hypertension should use two different approaches: novel titrations of conventional drugs to achieve a decrease in either SBP or pulse pressure, and development of new drugs acting selectively on the large artery wall, to facilitate the conduct of subsequent controlled trials.

Antihypertensive Agents↗
PubMed2006

A new triterpene synthase from Arabidopsis thaliana produces a tricyclic triterpene with two hydroxyl groups.

[structure: see text] Thirteen oxidosqualene cyclase homologues exist in the genome of Arabidopsis thaliana. One of these genes, At4g15340, was amplified by PCR and expressed in yeast. The yeast transformant accumulated tricyclic triterpene, (3S,13R)-malabarica-17,21-dien-3,14-diol (arabidiol), whose structure was determined by NMR and MS analyses. Its epoxide analogue, (3S,13R,21S)-malabarica-17-en-20,21-epoxy-3,14-diol (arabidiol 20,21-epoxide), was also isolated from the transformed yeast. This is the first example of a triterpene synthase that yields a tricyclic triterpene with two hydroxyl groups.

Arabidopsis↗
PubMed1991

Stereochemistry and size of sugar head groups determine structure and phase behavior of glycolipid membranes: densitometric, calorimetric, and X-ray studies.

The role carbohydrate moieties play in determining the structure and energetics of glycolipid model membranes has been investigated by small- and wide-angle X-ray scattering, differential scanning densitometry (DSD), and differential scanning microcalorimetry (DSC). The dependence of a variety of thermodynamic and structural parameters on the stereochemistry of the OH groups in the pyranose ring and on the size of the sugar head group has been studied by using an homologous series of synthetic stereochemically uniform glyceroglycolipids having glucose, galactose, mannose, maltose, or trimaltose head groups and saturated ether-linked alkyl chains with 10, 12, 14, 16, or 18 carbon atoms per chain. The combined structural and thermodynamic data indicate that stereochemical changes of a single OH group in the pyranose ring can cause dramatic alterations in the stability and in the nature of the phase transitions of the membranes. The second equally important determinant of lipid interactions in the membrane is the size of the head group. A comparison of lipids with glucose, maltose, or trimaltose head groups and identical hydrophobic moieties has shown that increasing the size of the neutral carbohydrate head group strongly favors the bilayer-forming tendency of the glycolipids. These experimental results provide a verification of the geometric model advanced by Israelachvili et al. (1980) [Israelachvili, J. N., Marcelja, S., & Horn, R. G. (1980) Q. Rev. Biophys. 13, 121-200] to explain the preferences lipids exhibit for certain structures. Generally galactose head groups confer highest stability on the multilamellar model membranes as judged on the basis of the chain-melting transition. This is an interesting aspect in view of the fact that galactose moieties are frequently observed in membranes of thermophilic organisms. Glucose head groups provide lower stability but increase the number of stable intermediate structures that the corresponding lipids can adopt. Galactolipids do not even assume a stable intermediate L alpha phase for lipids with short chain length but perform only Lc----HII transitions in the first heating. The C2 isomer, mannose, modifies the phase preference in such a manner that only L beta----HII changes can occur. Maltose and trimaltose head groups prevent the adoption of the HII phase and permit only L beta----L alpha phase changes. The DSD studies resulted in a quantitative estimate for the volume change associated with the L alpha----HII transition of 14-Glc. The value of delta v = 0.005 mL/g supports the view that the volume difference between L alpha and HII is minute.(ABSTRACT TRUNCATED AT 400 WORDS)

Calorimetry, Differential Scanning↗
PubMed2004

Development of a model for a structured support group for patients following bariatric surgery.

Bariatric surgery is performed to alleviate the major health problems associated with morbid obesity. However, after surgery, patients must learn to deal with new self-images and old behavior patterns that may precipitate a return to the pre-surgery status. Thus, long-term follow-up and continued emotional support are essential ingredients for a successful bariatric surgery outcome. Patients who attend group meetings regularly, tend to lose more weight. Patients are encouraged to participate in a structured support group both before and after bariatric surgery. The current model of the group incorporates self-responsibility, aspects of the "relapse prevention" model, and group therapy processes. Additionally the group is flexible, to adapt to the needs of the evolving group membership.

Feeding Behavior↗