Presence of luteinizing hormone-releasing hormone binding sites in cultured porcine lymphocytes.

Membrane-enriched homogenates of fresh and cultured (48 h) porcine lymphocytes were assayed for the presence of specific LHRH receptors by saturation and displacement analysis using [D-Ser-(TBU)6, des-Gly-NH2(10)] LHRH-EA as the labeled and unlabeled ligand. Membrane-enriched homogenates of porcine pituitaries served as positive controls while porcine granulosa cell membranes and crude liver homogenates served as negative controls. Specific high-affinity LHRH receptors were found in porcine pituitaries (Kd = 0.3 nM) and cultured lymphocytes (Kd = 13 nM) but not in fresh lymphocytes. No specific binding was observed in negative control tissues. Porcine lymphocytes have measurable high-affinity LHRH receptors after 48 h of culture.     

The landscape of metabolic pathway dependencies in cancer cell lines

The metabolic reprogramming of cancer cells creates metabolic vulnerabilities that can be therapeutically targeted. However, our understanding of metabolic dependencies and the pathway crosstalk that creates these vulnerabilities in cancer cells remains incomplete. Here, by integrating gene expression data with genetic loss-of-function and pharmacological screening data from hundreds of cancer cell lines, we identified metabolic vulnerabilities at the level of pathways rather than individual genes. This approach revealed that metabolic pathway dependencies are highly context-specific such that cancer cells are vulnerable to inhibition of one metabolic pathway only when activity of another metabolic pathway is altered. Notably, we also found that the no single metabolic pathway was universally essential, suggesting that cancer cells are not invariably dependent on any metabolic pathway. In addition, we confirmed that cell culture medium is a major confounding factor for the analysis of metabolic pathway vulnerabilities. Nevertheless, we found robust associations between metabolic pathway activity and sensitivity to clinically approved drugs that were independent of cell culture medium. Lastly, we used parallel integration of pharmacological and genetic dependency data to confidently identify metabolic pathway vulnerabilities. Taken together, this study serves as a comprehensive characterization of the landscape of metabolic pathway vulnerabilities in cancer cell lines.     

A key metabolic integrator,coenzyme A,modulates the activity of peroxiredoxin 5 via covalent modification

Molecular and Cellular Biochemistry - Cisplatin has been extensively used as a chemotherapeutic agent since around 40 years, though its usage is limited due to severe adverse effects like...     

Systematic nocturnal atrial demand pacing results in high-output heart failure.

Beat-to-beat parameters of heart rate (HR), intra-arterial blood pressure (BP), central venous pressure, and derived indexes of cardiac output and total peripheral resistance were recorded 18 h/day (from 1800 to 1200 h the following day) in four monkeys (Macaca mulatta) during 20 control days followed by 20 days of atrial demand pacing. The pacing rate was set at approximately 10 beats/min above the fastest hourly average HR recorded during the control period, i.e., sufficient to prevent the normal nocturnal fall in HR. Nocturnal pacing resulted in progressive weekly increases in central venous BP and arterial BP. Analyses of levels and diurnal trends in hemodynamic parameters and cardiac function curves across consecutive 5-day periods of nocturnal pacing revealed a hemodynamic pattern characteristic of high-output heart failure, which progressively increased (week by week) during the early morning hours (0500-0700). Sustained elevated left ventricular work resulting from the prevention of a nocturnal fall in HR may have been responsible for the reduction in cardiac function seen in this experimental model.     

Effect of nocturnal atrial demand cardiac pacing on diurnal hemodynamic patterns.

Heart rate (HR), stroke volume (SV), intra-arterial blood pressure, and central venous pressure were recorded on a beat-to-beat basis, 18 h/day (1800-1200 h the following day), for approximately 2 mo in four monkeys (Macaca mulatta). Cardiac output, left ventricular work, and total peripheral resistance were derived from these primary measurements. During the 1st mo we measured these parameters under control conditions, and during the 2nd mo the animals were studied while HR was paced by atrial demand pacing sufficient to prevent the normal nocturnal fall in HR (approximately 10 beats/min above the fastest hourly average rate recorded during the control condition). The main hypothesis of this study was that when HR is prevented from falling, SV, which normally does not fall overnight, would fall; this hypothesis was confirmed. In addition, we observed that, during the period of pacing, relative to the control period, SV was approximately 14% greater during the early evening and 4% lower during the early morning; total peripheral resistance was similar during the early evening but was 13% higher by morning. Throughout the night, systolic pressure was approximately 4% greater, diastolic pressure was 17% higher, central venous pressure was 43% greater, and left ventricular work was 27% higher. These findings show that when HR is prevented from falling overnight by atrial demand pacing, even to a relatively modest degree, there can be very significant sustained changes in cardiovascular function.     

Rab11a redistributes to apical secretory canaliculus during stimulation of gastric parietal cells

Previous investigations in several systems have demonstratedthat Rab3 family members redistribute to soluble fractions on fusion ofsecretory granules with target plasma membranes. Rab proteins are thenrecycled back onto mature secretory vesicles after reinternalization ofthe membrane. Although this cycle is well established for Rab3, farless is known about redistribution of other Rab proteins during vesiclefusion and recycling. In the gastric parietal cell, Rab11a isassociated with H-K-ATPase-containing tubulovesicles, which fuse withthe apical plasma membrane (secretory canaliculus) in response toagonists such as histamine. We have analyzed distribution of Rab11a andother tubulovesicle proteins in resting and histamine-stimulated rabbitparietal cells. Stimulation of isolated gastric glands in the presenceof 100 µM histamine and 100 µM 3-isobutyl-1-methylxanthine did notcause a significant increase in soluble Rab11a. H-K-ATPase, Rab11a,Rab25, syntaxin 3, and SCAMPs increased immunoreactivity instimulus-associated vesicles prepared from rabbits treated withhistamine compared with those from ranitidine-treated animals. Thelarge GTPase dynamin was found in both vesicle preparations, but therewas no change in amount of immunoreactivity. Immunofluorescencestaining of resting and histamine-stimulated primary cultures ofparietal cells demonstrated redistribution of H-K-ATPase and Rab11a to F-actin-rich canalicular membranes. Dynamin was present on canalicular membranes in resting and stimulated cells. These results indicate thatRab11a does not cycle off the membrane during the process oftubulovesicle fusion with the secretory canaliculus. Thus Rab11a mayremain associated with recycling apical membrane vesicle populations.

     

Comparative role of retinol, retinoic acid and beta-carotene on progesterone secretion by pig corpus luteum in vitro

Quadruplicate wells of pig luteal cells were incubated for 24 h in the presence of different concentrations of retinol, beta-carotene (0, 1 x 10(-5), 1 x 10(-6) and 1 x 10(-7) M) or retinoic acid (0, 1 x 10(-6), 1 x 10(-7) and 1 x 10(-8) M). In addition, the responsiveness of luteal cells to LH challenge was also evaluated. Progesterone was assayed in the media. Cell viability was estimated using trypan blue exclusion and showed over 95% viability. In the presence of LH, progesterone content in the medium was increased by 7-fold. As compared to their respective controls, all concentrations of retinoic acid and beta-carotene increased progesterone content in the media. The highest level of stimulation was observed with 1 x 10(-6) M-retinoic acid (5-fold increase) and 1 x 10(-7) M-beta-carotene (10-fold increase). Only 1 x 10(-5) M-retinol stimulated progesterone secretion (over 3-fold). Therefore, retinol, retinoic acid and beta-carotene stimulate progesterone secretion by pig luteal cells in vitro.