Rapid, transient phosphatidylserine externalization induced in host cells by infection with Chlamydia spp

Chlamydia organisms are obligate intracellular bacterial pathogens responsible for a range of human diseases. Persistent infection or reinfection with Chlamydia trachomatis leads to scarring of ocular or genital tissues, and Chlamydia pneumoniae infection is associated with the development of atherosclerosis. We demonstrate that C. trachomatis and C. pneumoniae infection in vitro elicits the externalization of the lipid phosphatidylserine on the surface of human epithelial, endothelial, granulocytic, and monocytic cells. Phosphatidylserine externalization is associated with cellular development, differentiation, and death. Infection-induced phosphatidylserine externalization was immediate, transient, calcium dependent, and infectious dose dependent and was unaffected by a broad-spectrum caspase inhibitor. Chlamydia-infected cells accelerated plasma clotting and increased the macrophage phagocytosis of infected cells that was phosphatidylserine dependent. The rapid externalization of phosphatidylserine by infected cells may be an important factor in the pathogenesis of chlamydial infections.     

A molecular clone of simian-human immunodeficiency virus (DeltavpuSHIV(KU-1bMC33)) with a truncated, non-membrane-bound vpu results in rapid CD4(+) T cell loss and neuro-AIDS in pig-tailed macaques

We report on the role of vpu in the pathogenesis of a molecularly cloned simian-human immunodeficiency virus (SHIV(KU-1bMC33)), in which the tat, rev, vpu, env, and nef genes derived from the uncloned SHIV(KU-1b) virus were inserted into the genetic background of parental nonpathogenic SHIV-4. A mutant was constructed (DeltavpuSHIV(KU-1bMC33)) in which 42 of 82 amino acids of Vpu were deleted. Phase partitioning studies revealed that the truncated Vpu was not an integral membrane protein, and pulse-chase culture studies revealed that cells inoculated with DeltavpuSHIV(KU-1bMC33) released viral p27 into the culture medium with slightly reduced kinetics compared with cultures inoculated with SHIV(KU-1bMC33). Inoculation of DeltavpuSHIV(KU-1bMC33) into two pig-tailed macaques resulted in a severe decline of CD4(+) T cells and neurological disease in one macaque and a more moderate decline of CD4(+) T cells in the other macaque. These results indicate that a membrane-bound Vpu is not required for the CD4(+) T cell loss and neurological disease in SHIV-inoculated pig-tailed macaques. Furthermore, because the amino acid substitutions in the Tat and Rev were identical to those previously reported for the nonpathogenic SHIV(PPc), our results indicate that amino acid substitutions in the Env and/or Nef were responsible for the observed CD4(+) T cell loss and neurological disease after inoculation with this molecular clone.     

Effect of oral creatine ingestion on parameters of the work rate-time relationship and time to exhaustion in high-intensity cycling

The relationship between work rate (W˙) and time to exhaustion (t) during intense exercise is commonly described by either a hyperbolic function (NLin), t=W ^′/(W˙?W˙ _cp), or by its linear equivalent (LinW) W _lim =W ^′+W˙ _cp(t). The parameter W˙<INF _cp (critical power) has been described as an inherent characteristic of the aerobic energy system, while W?′ has been shown to be a ralid estimate of anaerobic work capacity. Recent studies have demonstrated that oral supplementation of creatine monohydrate (CrH₂O) increases total muscle creatine stores, and have linked these increases to improved performances in intense intermittent exercise. This study was conducted to determine the effect of CrH₂O supplementation on estimates of W?′ and W˙<INF _cp derived from the NLin and LinW equations, and to determine the effect of CrH₂O on t in exhaustive constant power exercise of different intensities. Fifteen active but untrained university students completed three phases of testing on a cycle ergometer: (1) familiarization, three learning trials, (2) baseline determination of W?′ and W˙<INF _cp, four bouts performed at a W˙ selected to elicit fatigue in 90–600?s, and (3) experimental determination of W?′ and W˙ _cp, four bouts performed at the same W˙ as baseline, but performed after 5 days of ingesting either a placebo (4?×?6?g of glucose/day) or CrH₂O (4?×?5?g of CrH₂O and 1?g glucose/day). Testing was administered in a double-blind manner. Analyses of covariance revealed a significant effect for CrH₂O on both estimates of W?′ (NLin, P=0.04; LinW, P<0.01), but not on estimates of W˙ _cp (NLin, P=0.37; LinW; P=0.30). Within groups, t was significantly different for only CrH₂O at the two highest W˙s (P=0.04). It is concluded that oral ingestion of CrH₂O increases estimates of W?′ due to an improved t at the shorter, more intense exercise bouts.

     

Retinoic acid is required for endodermal pouch morphogenesis and not for pharyngeal endoderm specification.

Because tissues from all three germ layers contribute to the pharyngeal arches, it is not surprising that all major signaling pathways are involved in their development. We focus on the role of retinoic acid (RA) signaling because it has been recognized for quite some time that alterations in this pathway lead to craniofacial malformations. Several studies exist that describe phenotypes observed upon RA perturbations in pharyngeal arch development; however, these studies did not address whether RA plays multiple roles at distinct time points during development. Here, we report the resulting phenotypes in the hindbrain, the neural crest-derived tissues, and the pharyngeal endoderm when RA synthesis is disrupted during zebrafish gastrulation and pharyngeal arch morphogenesis. Our results demonstrate that RA is required for the post-gastrulation morphogenesis and segmentation of endodermal pouches, and that loss of RA does not affect the length of the pharyngeal ectoderm or medial endoderm along the anterior-posterior axis. We also provide evidence that RA is not required for the specification of pharyngeal pouch endoderm and that the pharyngeal endoderm consists of at least two different cell populations, of which the pouch endoderm is sensitive to RA and the more medial pharyngeal endoderm is not. These results demonstrate that the developmental processes underlying pharyngeal arch defects differ depending on when RA signaling is disturbed during development.     

Discriminative stimulus properties of β-carbolines characterized as agonists and inverse agonists at central benzodiazepine receptors

The discriminative stimulus properties of three -carboline derivatives were studied in three groups of rats trained, respectively, to discriminate diazepam (2.5 mg/kg IP), chlordiazepoxide (CDP, 5 mg/kg IP) or pentylenetetrazol (PTZ, 15 mg/kg IP) from saline in standard procedures employing two-lever operant chambers. Two -carbolines, ZK 91296 and ZK 93423, substituted for the benzodiazepines in both CDP- and diazepam-trained rats. The neutral benzodiazepine antagonist Ro 15-1788 blocked the diazepam discriminative stimulus and the ability of ZK 91296 to substitute for diazepam. A third -carboline, FG 7142, was not identified as benzodiazepine-like in generalization tests in either diazepam- or CDP-trained rats, but when administered together with CDP antagonized the benzodiazepine discriminative stimulus. In rats trained to discriminate PTZ from saline (a discrimination which is thought to depend on the anxiogenic properties of PTZ) the PTZ cue was antagonized by diazepam and ZK 93423, and partially antagonized by ZK 91296. The PTZ cue generalized to FG 7142 and this generalization was partially antagonized by Ro 15-1788. These results suggest that the three -carbolines provide more than one kind of discriminative stimulus, consistent with the classification of ZK 93423 as an agonist at central benzodiazepine receptors, with ZK 91 296 as a partial agonist, and with FG 7142 as an inverse agonist. Pharmacologically, ZK 93 423 and ZK 91 296 may exhibit anxiolytic qualities, whereas FG 7142 produces anxiogenic effects.     

ZK 91296, a partial agonist at benzodiazepine receptors

ZK 91296 (ethyl 5-benzyloxy-4-methoxymethyl--carboline-3-carboxylate) is a potent and selective ligand for benzodiazepine (BZ) receptors. Biochemical investigations indicate that ZK 91296 may be a partial agonist at BZ receptors. Such partial agonism may explain to some extent why ZK 91296 needs higher BZ receptor occupancy than diazepam for the same effect against chemical convulsants and for behavioural effects. The lack of sedatiye effects, and the very potent inhibition of reflex epilepsy, spontaneous epilepsy and DMCM-induced seizures suggest, furthermore, that ZK 91296 may possess pharmacological selectivity for a particular type of BZ receptor interaction, perhaps including topographic as well as receptor subtype differentiation.     

Antagonism of the discriminative effects of ethylketazocine,cyclazocine, and nalorphine in macaques

dl-Ethylketazocine (EKC, 0.01 mg/kg) and saline were established as discriminative stimuli for food-maintained responding in macaque monkeys. Thirty consecutive presses on a right or left lever were reinforced with food, contingent on whether EKC or saline were administered before the session. For tests of antagonism, naltrexone, or UM 979 [(l)-5,9-alpha-dimethyl-2-(3-furylmethyl)-2-hydroxy-6,7-benzomorphan] was administered concomitantly with EKC,dl-cyclazocine, or nalorphine. Both antagonists blocked completely the EKC discriminative stimulus. The antagonism of the stimulus and rate-altering effects of EKC was surmountable, with considerable intersubject variability in the magnitude of the EKC dose increase required to overcome the blockade. Cyclazocine and nalophine, mixed agonist-antagonist opioids that share stimulus properties with EKC, were also susceptible to antagonism. Naltrexone antagonized completely the EKC stimulus effects of nalorphine; naltrexone and UM 979 antagonized completely the EKC stimulus effects of cyclazocine. Naltrexone antagonism of the cyclazocine stimulus was not surmountable, due to a lack of antagonism of the rate-decreasing effects of high cyclazocine doses.     

Postoperative thyroid hormone supplementation rates following thyroid lobectomy

BackgroundThyroid lobectomy is performed for symptomatic benign nodules, indeterminate nodules, or low-risk well differentiated thyroid cancer. We aimed to determine factors associated with thyroid stimulating hormone over goal (TH) following lobectomy.MethodsWe performed a retrospective single-institution cohort study of patients undergoing thyroid lobectomy from January 2016 to December 2017. TH was defined as need for thyroid hormone in accordance with guidelines. Univariate and multivariate logistic regression analysis was performed.ResultsOne hundred patients were included and 47% developed.TH73% of those with cancer, 38% with benign pathology (p = 0.002). Patients with TH were more likely to have thyroiditis 26% versus 3.8% (p = 0.002); higher preoperativeTSHmean 1.88mIU/L (SD 1.17) versus 1.16mIU/L (SD 0.77) (p = 0.0002), and smaller remnant thyroid lobe adjusted for body surface area 2.99ml/m2 versus 3.72ml/m2 (p = 0.003).ConclusionsAfter thyroid lobectomy, TH is associated with preoperative TSH level, thyroiditis, remnant thyroid volume, and malignancy. The majority of patients with final pathology of carcinoma will require thyroid hormone supplementation to achieve TSH goal.