In vivo bone strain on the dog tibia during locomotion

Rosette and single-element strain gauges were implanted on the tibia in 2 dogs and recordings were made during locomotion on a treadmill. At foot contact and during the swing phase of locomotion, bone strains were low and directions of the principal strains were variable. There was a large shift in the directions of the principal strains at the beginning of the stance phase and bone strains were considerably higher. Peak strain occurred midway through the stance phase. At that time, the maximum principal strain (tension) was directed upwards and anteriorly between 30 and 60 degrees with respect to the long axis of the tibia. These bone strain patterns in the dog are similar to those found in sheep while both differ markedly from those found in humans.     

Age estimation in rhesus macaques (Macaca mulatta) based on mandibular dimensions

A new technique has been developed for estimating age in rhesus macaques (Macaca mulatta) that is based on mandibular measurements and has several advantages over presently available techniques. First, the new technique is relatively quick and inexpensive because a single measurement or radiograph suffices to produce an age estimate. Second, mandibular growth represents a more continuous phenomenon than either epiphyseal union or dental eruption; therefore, age estimates may be made throughout the period of growth without significant gaps in the process. Finally, the new technique may be used on incomplete or even fragmentary skeletal material because it requires that only a portion of the mandible be preserved. The new technique produces age estimates with a prediction error of ±5.08 months in males and ±7.29 months in females. These errors are only slightly higher than those found previously for dental eruption or epiphyseal union data.     

Mechanisms of HIV-1 evasion to the antiviral activity of chemokine CXCL12 indicate potential links with pathogenesis

HIV-1 infects CD4 T lymphocytes (CD4TL) through binding the chemokine receptors CCR5 or CXCR4. CXCR4-using viruses are considered more pathogenic, linked to accelerated depletion of CD4TL and progression to AIDS. However, counterexamples to this paradigm are common, suggesting heterogeneity in the virulence of CXCR4-using viruses. Here, we investigated the role of the CXCR4 chemokine CXCL12 as a driving force behind virus virulence. In vitro, CXCL12 prevents HIV-1 from binding CXCR4 and entering CD4TL, but its role in HIV-1 transmission and propagation remains speculative. Through analysis of thirty envelope glycoproteins (Envs) from patients at different stages of infection, mostly treatment-naïve, we first interrogated whether sensitivity of viruses to inhibition by CXCL12 varies over time in infection. Results show that Envs resistant (RES) to CXCL12 are frequent in patients experiencing low CD4TL levels, most often late in infection, only rarely at the time of primary infection. Sensitivity assays to soluble CD4 or broadly neutralizing antibodies further showed that RES Envs adopt a more closed conformation with distinct antigenicity, compared to CXCL12-sensitive (SENS) Envs. At the level of the host cell, our results suggest that resistance is not due to improved fusion or binding to CD4, but owes to viruses using particular CXCR4 molecules weakly accessible to CXCL12. We finally asked whether the low CD4TL levels in patients are related to increased pathogenicity of RES viruses. Resistance actually provides viruses with an enhanced capacity to enter naive CD4TL when surrounded by CXCL12, which mirrors their situation in lymphoid organs, and to deplete bystander activated effector memory cells. Therefore, RES viruses seem more likely to deregulate CD4TL homeostasis. This work improves our understanding of the pathophysiology and the transmission of HIV-1 and suggests that RES viruses’ receptors could represent new therapeutic targets to help prevent CD4TL depletion in HIV+ patients on cART.     

Porcine D-amino acid oxidase: production of the biologically active enzyme in Escherichia coli

DNA molecules coding either for mature porcine D-amino acid oxidase or for truncated forms of the enzyme have been obtained by stepwise addition of synthetic oligonucleotides to a partial cDNA. Under the control of the lambda PL thermoregulatable promoter, these DNAs were respectively expressed in Escherichia coli as 36, 28 and 25 kilodalton polypeptides, specifically recognised by antibodies raised against the natural enzyme. None of the truncated proteins were biologically active whereas the mature recombinant species was able to hydrolyze D-alanine in vitro as efficiently as the natural product.     

Effects of acute and chronic administration of sotalol on the blood pressure and the sympathoadrenal activity of anesthetized deoxycorticosterone acetate-salt hypertensive rats

Using plasma catecholamine (CA) levels as an index of the sympathoadrenal activity, the effects of chronic and acute beta-blockade on the blood pressure and sympathetic activity were evaluated in deoxycorticosterone acetate (DOCA) - salt hypertensive (HT) rats. The acute administration of one beta-blocker (sotalol, 5 mg/kg) to intact of vagotomized anesthetized HT animals induced a significant decrease in plasma norepinephrine (NE) concentrations and mean arterial pressure (MAP). The amplitude of the decrease of the MAP or NE levels were linearly correlated with the basal NE levels, suggesting that sotalol reduced the blood pressure and sympathetic NE release more efficiently in rats with increased sympathetic activity. Similarly, chronic infusion of sotalol (1.5 mg X day-1 X rat-1) through an osmotic pump for 12 days in DOCA-salt HT rats significantly reduced NE and epinephrine (E) plasma levels compared with those observed in untreated DOCA-salt HT rats. Moreover, the chronic treatment with sotalol significantly reduced the plasma E elevation induced by bilateral carotid occlusion (CO) in vagotomized normotensive (NT) and HT rats. It therefore appears that acute administration of sotalol to HT rats causes a significant reduction in the sympathetic activity which is associated to a decrease in MAP. Although chronic sotalol treatment causes a significant reduction in the sympathoadrenal basal activity and in the adrenal reactivity, this treatment did not prevent the development of DOCA-salt hypertension.     

The major surface protein of Leishmania promastigotes is a protease

The major surface protein of Leishmania promastigotes is evolutionarily conserved and is found in isolates of L. donovani, L. major, L. tropica, L. mexicana, and L. braziliensis. The data provided in this communication demonstrate that in L. major this integral membrane protein is a protease, which we now designate promastigote surface protease. The enzyme has an alkaline pH optimum and is active both in its detergent-solubilized form and at the surface of living or fixed promastigotes. A water-soluble form of promastigote surface protease is obtained following digestion with the phospholipase C responsible for the release of the variant surface glycoprotein of Trypanosoma brucei. Possible biological functions of promastigote surface protease during the life cycle of Leishmania parasites are discussed.     

Solubilization and Characterization of D2-Dopamine Receptors in an Estrone-Induced, Prolactin-Secreting Rat Pituitary Adenoma

D2-dopamine (3,4-dihydroxyphenylethylamine) receptors were successfully solubilized with 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate from an estrone-induced rat pituitary adenoma. Forty-five percent of initial protein and 48% of initial [3H]spiroperidol binding sites were solubilized. The high affinity as well as the stereoselectivity of the sites was preserved. The order of potency of dopaminergic agonists was found to be typical of D2 receptors. Target size analysis by radiation inactivation indicated a molecular weight of 143,000 +/- 3,000 and of 106,000 +/- 4,000 daltons for membrane-bound and solubilized receptors, respectively. This suggests the loss of a 37,000-dalton subunit during solubilization without significant modification of binding characteristics. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of receptor protein preparation photolabeled with N-(p-azido-m[125I]iodophenethyl)spiroperidol confirmed the existence of a 94,000-dalton peptide which probably constitutes the ligand binding site of the receptor. Thus, our data indicate that chronic estrogen treatment of rats, although inducing a pituitary adenoma, does not modify the pharmacological characteristics of D2 receptors. These data suggest therefore that these adenoma may represent an ideal source of material for further biochemical characterization of D2 receptors.     

Detection of sugar-binding proteins in membrane-depleted nuclei

Nuclear sugar-binding proteins were detected in membrane-depleted nuclei isolated from hamster BHK cells and mouse L 1210 leukemia cells by means of fluorescein-labelled neoglycoproteins. In fluorescence microscopy, the fluorescence was seen throughout the nucleus but was generally brighter over the nucleoli than over the rest of the nucleus. Flow cytofluorometry analysis demonstrated the presence of nuclear sugar-binding proteins for synthetic glycoproteins associated with different sugar residues. Among the nine neoglycoproteins used, four neoglycoproteins (namely alpha-rhamnosylated, alpha-glucosylated, N-acetyl-beta-glucosaminylated and alpha-mannosylated-6P-serum albumin) strongly labelled nuclei. Various controls strongly argue for the specificity of the nuclear labelling. The possibility that some of the sugar-binding proteins might correspond to endogenous nuclear lectins is considered.