Endogenous tissue engineering: PTH therapy for skeletal repair

Based on its proven anabolic effects on bone in osteoporosis patients, recombinant parathyroid hormone (PTH_1-34) has been evaluated as a potential therapy for skeletal repair. In animals, the effect of PTH_1-34 has been investigated in various skeletal repair models such as fractures, allografting, spinal arthrodesis and distraction osteogenesis. These studies have demonstrated that intermittent PTH_1-34 treatment enhances and accelerates the skeletal repair process via a number of mechanisms, which include effects on mesenchymal stem cells, angiogenesis, chondrogenesis, bone formation and resorption. Furthermore, PTH_1-34 has been shown to enhance bone repair in challenged animal models of aging, inflammatory arthritis and glucocorticoid-induced bone loss. This pre-clinical success has led to off-label clinical use and a number of case reports documenting PTH_1-34 treatment of delayed-unions and non-unions have been published. Although a recently completed phase 2 clinical trial of PTH_1-34 treatment of patients with radius fracture has failed to achieve its primary outcome, largely because of effective healing in the placebo group, several secondary outcomes are statistically significant, highlighting important issues concerning the appropriate patient population for PTH_1-34 therapy in skeletal repair. Here, we review our current knowledge of the effects of PTH_1-34 therapy for bone healing, enumerate several critical unresolved issues (e.g., appropriate dosing regimen and indications) and discuss the long-term potential of this drug as an adjuvant for endogenous tissue engineering.     

Kinetics of acetylation-deacetylation of angiotensin II. Intramolecular interactions of the tyrosine and histidine side-chains

The possible existence of intramolecular interactions involving the tyrosine and histidine residues in angiotensin II has been investigated by measuring the reactivities of the functional groups in the molecule. Angiotensin II catalyzed the hydrolysis of p-nitrophenylacetate in the pH range 6.6-8.2 at higher rates than were consistent with the reactivities of the free constituent functional groups, and had 2-4% of the activity of chymotrypsin between pH 6.6 and 7.5. Treatment of angiotensin II with acetic anhydride demonstrated that the tyrosine hydroxyl and the imidazole side-chain in angiotensin II acetylated and deacetylated at markedly higher rates than for the free amino acids, indicating increased nucleophilicities and the presence of intrinsic deacetylation mechanisms for these residues in angiotensin II. These findings are consistent with the presence of tyrosine hydroxyl-histidine-carboxylate charge relay system in ANG II in aqueous environments, and suggest that ANG II may act at membrane receptors by a mechanism which is analogous to that operating in serine proteases.     

Socially isolated? How parents and neighbourhood adults influence youth behaviour in disadvantaged communities

William Julius Wilson’s model of adult joblessness, community disorganization and their effects on youth problem behaviour de-emphasizes the range in children’s outcomes across socially disorganized communities, and says little about the factors that influence this variation. It also does not address the processes by which family structure and relationships affect the well-being of African-American and poor youth. My work is part of a larger research agenda that has begun to address these issues by focusing on the differential rates of sexual activity among youth living in disadvantaged environments, and developing models to explain this variation. This work suggests that units of socially cohesive, stable adults exist among the social networks of successful children and families in poor neighbourhoods. It also points to the existence and functioning of alternative two-parent family structures and offers hypotheses for how family environment interacts with neighbourhood context to influence youth behaviour.     

Profiling SARS-CoV-2 HLA-I peptidome reveals T cell epitopes from out-of-frame ORFs

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Improved micro-method for the high-performance liquid chromatographic determination of caffeine and paraxanthine in biological fluids

A high-performance liquid chromatographic procedure is reported for reproducibly and sensitively quantitating caffeine and its N-demethylated metabolite paraxanthine in micro-samples. A 5-μm reversed-phase radial compression column and 214-nm fixed wavelength ultraviolet detector were used to attain a sensitivity sufficient to quantitate these compounds at concentratios as low as 80 ng/ml using only 25 μl of sample. The assay is applicable to microliter samples of whole blood, serum, plasma, saliva, amniotic, cerebro-spinal and gastric fluids such as might be obtained in studies involving small animals or neonates. The utility of the assay is illustrated with caffeine and paraxanthine levels measured in several maternal and fetal fluids following constant-rate intravenous infusion of caffeine into a rabbit throughout pregnancy.     

COMPARISON OF ISOZYMES AMONG TYPHA SPECIES IN THE EASTERN UNITED STATES

Biochemical phenotsypes of four taxa of Typha from the eastern United States were determined by starch gel electrophoresis. The isozyme banding patterns of T. latifolia, T. angustifolia and T. domingensis are distinct and allow unambiguous species identification when morphological characters are inadequate or unsuitable. The fourth form, T. glauca, is not an F₁ hybrid, but it does appear to be intermediate between T. latifolia and T. angustifolia. The status of T. glauca and evolutionary relationships among the four forms may now be clarified by additional sampling because of the distinct and relatively invariant isozyme banding patterns which are described.     

Identification of a GM1-Binding Protein on the Surface of Murine Neuroblastoma Cells

S20Y murine neuroblastoma cells appear to express a protein component(s) able to adhere specifically to the oligosaccharide portion of GM1 (oligo-GM1). To identify proteins with which the oligo-GM1 becomes closely associated, a radiolabeled (125I), photoactivatable derivative of oligo-GM1 was prepared. This was accomplished by reductive amination of the glucosyl moiety of oligo-GM1 to 1-deoxy-1-aminoglucitol, followed by reaction of the amine with sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (SASD). Crosslinking studies using the photoactivatable probe indicated that it came in close proximity to a protein with an apparent molecular mass of approximately 71 kDa. In competition experiments, as little as a 10-fold molar excess of oligo-GM1 resulted in a selective reduction in labeling of this protein; preincubation with a 200-fold molar excess of siayllactose was necessary to observe the same change in the labeling pattern, lending additional support to the hypothesis that the approximately 71-kDa protein specifically associates with oligo-GM1. Cell surface location of the oligo-GM1 binding protein was confirmed using subcellular fractionation and morphological analyses.     

Round robin investigation of methods for recovering human enteric viruses from sludge

To select a tentative standard method for detection of viruses in sludge the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group initiated round robin comparative testing of two procedures that, after initial screening of several methodologies, were found to meet the basic criteria considered essential by the task group. Eight task group member laboratories agreed to perform round robin testing of the two candidate methods, namely, The Environmental Protection Agency or low pH-AlCl3 method and the Glass or sonication-extraction method. Five different types of sludge were tested. For each particular type of sludge, a single laboratory was designated to collect the sludge in a single sampling, make samples, and ship it to the participating laboratories. In most cases, participating laboratories completed all the tests within 48 h of sample arrival. To establish the reproducibility of the methods, each laboratory tested each sludge sample in triplicate for the two candidate virus methods. Each processed sludge sample was quantitatively assayed for viruses by the procedures of each individual round robin laboratory. To attain a more uniform standard of comparison, a sample of each processed sample from all laboratories was reassayed with one cell line and passage number by a single laboratory (Environmental Protection Agency Environmental Monitoring and Support Laboratory, Cincinnati, Ohio). When the data were statistically analyzed, the Environmental Protection Agency method was found to yield slightly higher virus recoveries for all sludge types, except the dewatered sludge. The precisions of both methods were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)