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.     

Existence of Sites for Anions and Divalent Cations in the Solubilized γ-Aminobutyric Acid/Benzodiazepine Receptor Complex

This study evaluated the ability of gamma-aminobutyric acid (GABA), baclofen, monovalent anions, divalent cations, and various combinations thereof to protect solubilized benzodiazepine (BZ) receptors of types 1 and 2, when contained together on the complex, against heat inactivation. Neither anions, cations, nor GABA alone provided significant protection of solubilized BZ receptors against heat, but inclusion of monovalent anions or divalent cations together with 500 microM GABA did afford protection. Monovalent anions combined with GABA (500 microM) provided 50% to full protection. Divalent cations, such as CaCl2 (2.5 mM) or MgCl2 (2.5 mM) in the presence of GABA (500 microM) yielded 45% and 24% protection, respectively. Other divalent cations tested (Zn2+, Hg2+, Co2+, and Ni2+) were poor protectors, even when combined with GABA. Monovalent anions (200 mM NaCl) and divalent cations (5 mM CaCl2) when tested together provided no protection. Similarly, baclofen (the GABA-B agonist) provided no protection, either alone or together with anions or divalent cations. These results indicate that the independent but interacting recognition sites of GABA, BZ, anions, and divalent cations, previously detected in the membrane-bound state, are retained in the solubilized state.     

The complete nucleotide sequence of the colicinogenic plasmid ColA. High extent of homology with ColE1

Summary The complete nucleotide sequence of the colicinogenic plasmid ColA has been determined. The plasmid DNA consists of 6720 bp (molecular weight 4.48×10⁶). Fifteen putative biological functions have been identified using the functional map previously determined. These include 11 genes and 3 DNA sites. Nine genes encode proteins of which 3 have been fully characterized. The replication region of ColA coding for RNAI and RNAII is highly homologous to that of ColE1 andClo DF13. The same holds true for the site-specific recombination region containing palindromic symmetry and involved in stable maintenance of the plasmids. A high percentage of homology has been detected for putative mobility proteins encoded by ColA and ColE1. The exclusion proteins are also highly homologous.     

Peripheral-type benzodiazepine receptors in human cerebral cortex, kidney, and colon.

The specific binding of [3H]PK 11195 and [3H]Ro 5-4864 to human cerebral cortex, kidney, and colon membranes was studied in order to determine whether peripheral type benzodiazepine receptors (PBR) characteristics located in human tissues are similar to those located in calf or rat tissues. While [3H]PK 11195 (0.05-10 nM, final concentration) bound with high affinity (KD about 2 nM) to human cerebral cortex, kidney, and colon membranes, yielding maximal numbers of binding sites of 255 +/- 23, 1908 +/- 28, and 1633 +/- 98 fmol/mg protein, respectively, the specific binding of [3H]Ro 5-4864 (1.25-40 nM, final concentration), was barely detectable (nonspecific binding about 90% of the total binding). Furthermore, unlabeled PK 11195 was two orders of magnitude more potent than unlabeled Ro 5-4864 in displacing [3H]PK 11195 specific binding from human cerebral cortex and kidney membranes. These results indicate that PBR binding characteristics located in human tissues are similar (but not identical) to those located in calf tissues, but not to those located in rat tissues.     

Emphysematous pyelonephritis

A case of emphysematous pyelonephritis with perirenal gas is presented. This patient underwent vigorous medical treatment followed by nephrectomy and survived. This condition has a high mortality and should be distinguished from less severe infections where gas is confined to the collecting system. This case and others previously reported suggest that treatment should initially be medical, followed by early surgical intervention consisting of either drainage or nephrectomy depending upon the degree of renal involvement.     

Camel myoglobin

1. Crystalline myoglobin was prepared from camel heart muscle. 2. A method was developed for the isolation of myoglobin that employs molecular-sieve chromatography. 3. Analytical chromatography of the camel myoglobin on a molecular-sieve column and on two types of ion-exchange columns gave in each case a single elution band, which accounted for better than 98% recovery and showed that the product was free from haemoglobin. 4. The iron content on a dry weight basis was 0.308%. This value corresponds to a molecular weight of 18100. 5. The spectra of acidic ferrimyoglobin, basic ferrimyoglobin and ferrimyoglobin cyanide were measured. 6. The pK(a) of the dissociation of the haem-bound water molecule in acidic ferrimyoglobin was 8.53 at 25 degrees . 7. Conclusions are drawn about the charge on the surface of the camel ferrimyoglobin molecule as compared with horse and sperm-whale ferrimyoglobins.     

Non-linear loss of suitable wine regions over Europe in response to increasing global warming

Evaluating the potential climatic suitability for premium wine production is crucial for adaptation planning in Europe. While new wine regions may emerge out of the traditional boundaries, most of the present-day renowned winemaking regions may be threatened by climate change. Here, we analyse the future evolution of the geography of wine production over Europe, through the definition of a novel climatic suitability indicator, which is calculated over the projected grapevine phenological phases to account for their possible contractions under global warming. Our approach consists in coupling six different de-biased downscaled climate projections under two different scenarios of global warming with four phenological models for different grapevine varieties. The resulting suitability indicator is based on fuzzy logic and is calculated over three main components measuring (i) the timing of the fruit physiological maturity, (ii) the risk of water stress and (iii) the risk of pests and diseases. The results demonstrate that the level of global warming largely determines the distribution of future wine regions. For a global temperature increase limited to 2°C above the pre-industrial level, the suitable areas over the traditional regions are reduced by about 4%/°C rise, while for higher levels of global warming, the rate of this loss increases up to 17%/°C. This is compensated by a gradual emergence of new wine regions out of the traditional boundaries. Moreover, we show that reallocating better-suited grapevine varieties to warmer conditions may be a viable adaptation measure to cope with the projected suitability loss over the traditional regions. However, the effectiveness of this strategy appears to decrease as the level of global warming increases. Overall, these findings suggest the existence of a safe limit below 2°C of global warming for the European winemaking sector, while adaptation might become far more challenging beyond this threshold.     

Widespread formation of intracellular calcium carbonates by the bloom-forming cyanobacterium Microcystis

The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom-forming cyanobacterium found worldwide in freshwater ecosystems. If iACC-forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here, we investigate the significance of iACC biomineralization by Microcystis. First, the presence of iACC-forming Microcystis cells has been detected in several eutrophic lakes, indicating that this phenomenon occurs under environmental conditions. Second, some genotypic (presence/absence of ccyA, a marker gene of iACC biomineralization) and phenotypic (presence/absence of iACC) diversity have been detected within a collection of strains isolated from one single lake. This illustrates that this trait is frequent but also variable within Microcystis even at a single locality. Finally, one-third of publicly available genomes of Microcystis were shown to contain the ccyA gene, revealing a wide geographic and phylogenetic distribution within the genus. Overall, the present work shows that the formation of iACC by Microcystis is common under environmental conditions. While its biological function remains undetermined, this process should be further considered regarding the biology of Microcystis and implications on the Ca geochemical cycle in freshwater environments.     

Stress-induced assortative mating and the evolution of stress resistance

We show with a model that variation in environmental stress between generations facilitates the evolution of stress resistance through assortative mating. Stress induces delayed maturation of susceptible phenotypes, segregating their fertile period from resistant phenotypes. Assortment of mates enhances the responsiveness of populations to natural selection by inflating genetic variance. Thus, positive selection and inflated genetic variance in stressful environments can cause a strong evolutionary increase in resistance. By contrast, benign environments do not segregate phenotypes, and the random mating among phenotypes deflates genetic variance, leading to a weaker response to selection against resistance, assuming that resistance is costly. When environments vary randomly from benign to stressful, populations respond asymmetrically to negative and positive selection. This asymmetry (1) accelerates fixation of a resistance allele if resistance is generally favoured (stressful generations more frequent) but delays the loss of the allele if it is generally disfavoured (benign generations more frequent), and (2) it can push a resistance allele to fixation even when long‐term costs modestly exceed benefits. When resistance alleles pleiotropically delay mating, stress‐induced random mating has complementary effects. Serial autocorrelation in the stressor amplifies these effects. These results suggest a novel mechanism for the persistence of resistance polymorphisms.