The oxytocic effect of xylazine on the canine uterus

The effect of xylazine on intrauterine pressure was compared to that of prostaglandin and oxytocin in seven diestrual bitches. Microtipped pressure transducers were surgically implanted in the uteri of four bitches at 30 d diestrus and in three bitches at 60 d diestrus. Uterine contractile force was measured in the awake bitches on Day 1 and Day 2 following implantation. Uterine responses to intravenous prostaglandin (5 mug/kg), oxytocin (0.05 USP units/kg), and xylazine (0.22 mg/kg) were measured. In the 30-d diestrual bitches, prostaglandin and oxytocin increased intrauterine pressure to 67 and 69 mmHg, with the duration of action being 16 and 14 min, respectively. Xylazine increased intra-uterine pressure to 49 mmHg and had a duration of action of 8 min. All results were decreased but similar in the 60-d diestrual bitches. These findings indicate that xylazine, given intravenously, produces a transitory increase in intrauterine pressure in the diestrual bitch.     

Stereoselective excision of thymine glycol from oxidatively damaged DNA

DNA damage created by reactive oxygen species includes the prototypic oxidized pyrimidine, thymine glycol (Tg), which exists in oxidatively damaged DNA as two diastereoisomeric pairs. In Escherichia coli, Saccharomyces cerevesiae and mice, Tg is preferentially excised by endonuclease III (Endo III) and endonuclease VIII (Endo VIII), yNTG1 and yNTG2, and mNTH and mNEIL1, respectively. We have explored the ability of these DNA glycosylases to discriminate between Tg stereoisomers. Oligonucleotides containing a single, chromatographically pure (5S,6R) or (5R,6S) stereoisomer of Tg were prepared by oxidation with osmium tetroxide. Steady-state kinetic analyses of the excision process revealed that Endo III, Endo VIII, yNTG1, mNTH and mNEIL1, but not yNTG2, excise Tg isomers from DNA in a stereoselective manner, as reflected in the parameter of catalytic efficiency (k_cat/K_m). When DNA glycosylases occur as complementary pairs, failure of one or both enzymes to excise their cognate Tg stereoisomer from oxidatively damaged DNA could have deleterious consequences for the cell.     

Dopamine Receptors in the Human Dura Mater

Dopamine receptors (Dar) were studied as a component of the nervous dopaminergic system in the human dura mater. Dar were stained in several dural zones (vascular, perivascular, intervascular) in different regions (basal, calvarial, tentorial, occipital, frontal, parietal, temporal) of the cranial meninges. Specimens of human dura mater were harvested from autopsies of 10 elderly male subjects (age range, 60-75 years). Dar were labeled with specific (H3) markers, studied with radiobinding techniques (including liquid scintillation), stained for light microscope autoradiography, and measured by means of quantitative analysis of images. All results were evaluated with statistical analysis to identify significant results. More dural Dar were found in the basal region than in the calvarial one. Moreover, Dar are more abundant in the vascular and perivascular dural zone than in the intervascular one. The vascular distribution of Dar seemed to indicate that Dar play a role in the control of meningeal blood vessels. The location and distribution of D1 and D2 receptors in the human cranial dura mater confirmed the presence of a dopaminergic system, which could play an important role in controlling blood flow and/or other functions of meningeal membranes.     

Modifications induced by plasma of gestational hypertensive women on the Na+/K+-ATPase obtained from human placenta

Pyrimidines and purine (deoxy)nucleotides are the building blocks of DNA and RNA. Nucleoside diphosphate sugars, e.g. UDP-glucose, are the reactive intermediates in the synthesis of nearly all glycosidic bonds between sugars.In mammals the requirement for pyrimidines is met by UMP de novo synthesis and, to a greater or lesser extent, by salvage of free nucleosides. The exceptional compartmentation of the de novo synthesis with respect to mitochondrially-bound dihydroorotate dehydrogenase ('DHOdehase' or 'DHODH', EC 1.3.99.11) is one focus of the present work. DHODH activity was determined by the dihydroorotate-dependent oxygen consumption or by the UV absorption of the product orotate with mitochondria isolated from rodent and porcine tissues. For comparison, the cytochrome c and choline-dependent oxygen consumption of mitochondria from different tissues was measured. The highest specific activity of the rat DHODH was found in liver (2.3 × 10-3 µmol/min × mg protein) > kidney > heart. The application of known enzyme inhibitors Brequinar Sodium and Leflunomide for DHODH and sodium cyanide for cytochrome c oxidase verified the specificity of the activity tests used. The relation of DHODH activity versus that of cytochrome c oxidase revealed the lowest ratios in heart mitochondria and the highest in liver mitochondria. Since disorders in the mitochondrial energy metabolism could entail severe impairment of pyrimidine biosynthesis via respiratory-chain coupled DHODH, it is suggested to include improvement of pyrimidine nucleotide status in therapy protocols. (Mol Cell Biochem 174: 125–129, 1997)     

Determination of Evolutionary Relationships of Outbreak-Associated Listeria monocytogenes Strains of Serotypes 1/2a and 1/2b by Whole-Genome Sequencing

We used whole-genome sequencing to determine evolutionary relationships among 20 outbreak-associated clinical isolates of Listeria monocytogenes serotypes 1/2a and 1/2b. Isolates from 6 of 11 outbreaks fell outside the clonal groups or “epidemic clones” that have been previously associated with outbreaks, suggesting that epidemic potential may be widespread in L. monocytogenes and is not limited to the recognized epidemic clones. Pairwise comparisons between epidemiologically related isolates within clonal complexes showed that genome-level variation differed by 2 orders of magnitude between different comparisons, and the distribution of point mutations (core versus accessory genome) also varied. In addition, genetic divergence between one closely related pair of isolates from a single outbreak was driven primarily by changes in phage regions. The evolutionary analysis showed that the changes could be attributed to horizontal gene transfer; members of the diverse bacterial community found in the production facility could have served as the source of novel genetic material at some point in the production chain. The results raise the question of how to best utilize information contained within the accessory genome in outbreak investigations. The full magnitude and complexity of genetic changes revealed by genome sequencing could not be discerned from traditional subtyping methods, and the results demonstrate the challenges of interpreting genetic variation among isolates recovered from a single outbreak. Epidemiological information remains critical for proper interpretation of nucleotide and structural diversity among isolates recovered during outbreaks and will remain so until we understand more about how various population histories influence genetic variation.     

Tick/host interactions forIxodes holocyclus: Role,effects, biosynthesis and nature of its toxic and allergenic oral secretions

The Australian paralysis tickIxodes holocyclus occurs along the eastern coast of Australia. Its interaction with a wide variety of hosts causes a serious toxicosis (tick paralysis) in domestic pets and livestock (occasionally in wildlife and humans) as well as hypersensitivity reactions in humans. Tick paralysis in animals is usually fatal in the absence of speedy antitoxin treatment and human hypersensitivity may result in life-threatening anaphylaxis. The protection of such hosts against toxic or allergic effects by vaccination or desensitisation respectively has been the objective of most of our recent research.The role, biosynthesis and nature of the paralysing toxin (holocyclotoxin) and of the allergens is gradually being elucidated. In this review, some emphasis has been placed on recent research on the interactions of humans with this tick and on the partial characterisation of the allergens.     

Drivers of extinction risk in African mammals: the interplay of distribution state,human pressure,conservation response and species biology

Although conservation intervention has reversed the decline of some species, our success is outweighed by a much larger number of species moving towards extinction. Extinction risk modelling can identify correlates of risk and species not yet recognized to be threatened. Here, we use machine learning models to identify correlates of extinction risk in African terrestrial mammals using a set of variables belonging to four classes: species distribution state, human pressures, conservation response and species biology. We derived information on distribution state and human pressure from satellite-borne imagery. Variables in all four classes were identified as important predictors of extinction risk, and interactions were observed among variables in different classes (e.g. level of protection, human threats, species distribution ranges). Species biology had a key role in mediating the effect of external variables. The model was 90% accurate in classifying extinction risk status of species, but in a few cases the observed and modelled extinction risk mismatched. Species in this condition might suffer from an incorrect classification of extinction risk (hence require reassessment). An increased availability of satellite imagery combined with improved resolution and classification accuracy of the resulting maps will play a progressively greater role in conservation monitoring.     

Combined MTOR and autophagy inhibition: Phase I trial of hydroxychloroquine and temsirolimus in patients with advanced solid tumors and melanoma

The combination of temsirolimus (TEM), an MTOR inhibitor, and hydroxychloroquine (HCQ), an autophagy inhibitor, augments cell death in preclinical models. This phase 1 dose-escalation study evaluated the maximum tolerated dose (MTD), safety, preliminary activity, pharmacokinetics, and pharmacodynamics of HCQ in combination with TEM in cancer patients. In the dose escalation portion, 27 patients with advanced solid malignancies were enrolled, followed by a cohort expansion at the top dose level in 12 patients with metastatic melanoma. The combination of HCQ and TEM was well tolerated, and grade 3 or 4 toxicity was limited to anorexia (7%), fatigue (7%), and nausea (7%). An MTD was not reached for HCQ, and the recommended phase II dose was HCQ 600 mg twice daily in combination with TEM 25 mg weekly. Other common grade 1 or 2 toxicities included fatigue, anorexia, nausea, stomatitis, rash, and weight loss. No responses were observed; however, 14/21 (67%) patients in the dose escalation and 14/19 (74%) patients with melanoma achieved stable disease. The median progression-free survival in 13 melanoma patients treated with HCQ 1200mg/d in combination with TEM was 3.5 mo. Novel 18-fluorodeoxyglucose positron emission tomography (FDG-PET) measurements predicted clinical outcome and provided further evidence that the addition of HCQ to TEM produced metabolic stress on tumors in patients that experienced clinical benefit. Pharmacodynamic evidence of autophagy inhibition was evident in serial PBMC and tumor biopsies only in patients treated with 1200 mg daily HCQ. This study indicates that TEM and HCQ is safe and tolerable, modulates autophagy in patients, and has significant antitumor activity. Further studies combining MTOR and autophagy inhibitors in cancer patients are warranted.