β1-integrin mediates pressure-stimulated phagocytosis

Background

Extracellular pressure alterations in infection, inflammation, or positive pressure ventilation may influence macrophage phagocytosis. We hypothesized that pressure modulates β1-integrins to stimulate phagocytosis.

Methods

We assayed fibroblast phagocytosis of fluorescent latex beads at ambient or 20 mm Hg increased pressure, and macrophage integrin phosphorylation by Western blot.

Results

Pressure did not alter phagocytosis in β₁-integrin null GD25 fibroblasts, but stimulated phagocytosis in fibroblasts expressing wild-type β₁-integrin. In phorbol myristate acetate-differentiated THP-1 macrophages, pressure stimulated β₁-integrin T788/789 phosphorylation, but not S785 phosphorylation. Furthermore, pressure stimulated phagocytosis in cells expressing an inactivating S785A point mutation or a T788D substitution to mimic a constitutively phosphorylated threonine, but not in cells expressing an inactivating TT788/9AA mutation.

Conclusions

The effects of pressure on phagocytosis are not limited to macrophages but generalize to other phagocytic cells. These results suggest that pressure stimulates phagocytosis via increasing β₁-integrin T789 phosphorylation. Interventions that target β₁-integrin threonine 789 phosphorylation may modulate phagocytic function.     

CT of pregnancy-related complications

During pregnancy, the risk of radiation exposure to the fetus is increased so that more than the usual benefit is necessary to justify computed tomography (CT; or other radiation exposure) than in non-pregnant patients. In the setting of a life-threatening illness, CT may be indicated to assess for potentially fatal complications such as hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. After delivery, patients rarely develop serious problems requiring radiologic evaluation. When indicated, however, CT may be invaluable in making the diagnosis or determining the severity of peri- and post-partum complications, including uterine perforation, hemorrhage, endometritis, thrombophlebitis, and abscess formation. At times, CT may be the first to uncover conditions, such as post-partum cardiomyopathy, and heart failure, which are usually diagnosed by other modalities but may explain the symptoms for which the study was ordered. In some centers, CT pulmonary angiography represents the standard of care to diagnose pulmonary thromboembolism. In this article, we illustrate the spectrum of peri-partum and post-partum complications on CT to familiarize the radiologist with the CT features of these potentially life-threatening pregnancy-related complications.     

Discarding the Initial Aliquot of Blood Does Not Reduce Contamination Rates in Intravenous-Catheter-Drawn Blood Cultures

Although venipuncture is the preferred method for obtaining blood cultures, specimens often are obtained from intravenous catheters (IVC). For IVC-drawn blood cultures, some authorities recommend discarding the initial 5 to 10 ml of blood to reduce contamination and remove potential inhibitory substances. To determine whether this practice reduced contamination rates (CR), we assessed the results of IVC-drawn blood cultures for adults. Thirty milliliters of blood was obtained aseptically. The first 10 ml, rather than being discarded, was inoculated into an aerobic culture vial. Using a second sterile syringe, 20 ml of blood was obtained and inoculated in 10-ml aliquots to aerobic and anaerobic culture vials. Positive cultures were evaluated to assess clinical significance (true versus contaminant). Out of 653 IVC-drawn blood culture pairs, both vials were contaminated in 38 pairs (5.8%); only the “discard” vial was contaminated in 33 (5.1%); and only the “standard” vial was contaminated in 31 (4.7%). Overall CR were 10.9% for the discard vial versus 10.5% for the standard vial (P = 0.90). We conclude that discarding an initial aliquot of blood when obtaining blood cultures from IVCs does not reduce CR.The standard method for obtaining blood for culture is venipuncture using aseptic techniques. With greater utilization of intravenous access catheters (e.g., PICC, Hickman, etc.), blood cultures often are obtained from these devices, yet there is no standardized method for obtaining blood for culture by this technique. Several reports have demonstrated increased blood culture contamination rates (i.e., false-positive results) when blood cultures are obtained from catheters (4, 8, 10, 15), which, in turn, can lead to inappropriate antibiotic administration as well as additional unnecessary diagnostic testing. Some authorities recommend discarding the first 5 to 10 ml of blood when obtaining blood from intravenous catheters (IVCs) prior to inoculating the blood culture vials (17), whereas others do not (1, 9, 16). The purpose of discarding these aliquots of blood is to remove any substances that could potentially inhibit microbial growth (e.g., heparin) (6, 19) and to reduce blood culture contamination rates. However, there are few published systematic assessments of this issue, no consensus recommendations on how to draw blood cultures from an IVC, and no controlled comparative evaluations of different techniques to obtain blood culture samples from an IVC.It has been standard practice at our institution to discard the first 10 ml of blood prior to obtaining blood for culture from IVCs. If patients have repeated blood cultures, in which 10 ml of blood is discarded with each culture, nosocomial anemia may occur or worsen and result in added morbidity (1, 3, 11, 18, 21). To determine whether discarding the initial aliquot of blood from IVC-drawn blood cultures reduces contamination, we inoculated the initial 10-ml sample of blood that would have been discarded into an aerobic blood culture vial and compared contamination rates in these vials with contamination rates in the “standard” blood sample obtained for culture from the same patient.     

Peptide-Based Antibody Detection for Tuberculosis Diagnosis

Tuberculosis (TB) is a major cause of morbidity and mortality, especially in developing countries. Despite significant limitations, microscopy remains the cornerstone of the global TB control strategy. As the TB epidemic escalates, new diagnostic methods that are accurate and also economical and simple to manufacture and deploy are urgently needed. Although several promising antigens have been identified and evaluated in recent years, the reproducible production of high-quality recombinant mycobacterial proteins with minimal batch-to-batch variation is difficult, laborious, and expensive. To determine the feasibility of devising a synthetic peptide-based diagnostic test for TB, we have delineated the immunodominant epitopes of three candidate antigens, Ag85B, BfrB, and TrxC, that were previously identified to be immunogenic in TB patients. The results demonstrate that combinations of carefully selected synthetic peptides derived from highly immunogenic proteins can be the basis for devising an immunodiagnostic test for TB.     

A primitive social circuit: vasotocin-substance P interactions modulate social behavior through a peripheral feedback mechanism in goldfish

At its core, the polyvagal theory proposes that peptides affect simple social behaviors through influences on hindbrain autonomic processes. To test this mechanism, we compared the effects of fore- and hindbrain infusions of vasotocin (VT) on social approach behavior in goldfish. VT infusions into the 4th ventricle, which ink infusions verified did not move rostrally to the forebrain, inhibited social approach at a lower dose than did infusions into the 3rd ventricle, which did diffuse to the hindbrain. Thus, VT actions in the hindbrain appear to modulate this simple social behavior. We then identified a population of substance P (SP)-immunoreactive cells in the hindbrain that are encapsulated by putative VT terminals, and determined that those cells project to the periphery. Injecting SP peripherally, as with infusing VT centrally, inhibited social approach, and peripheral injections of an SP antagonist, but not central infusions, abolished the behavioral effects of central VT infusions. We therefore propose that VT inhibits social approach by activating SP cells in the hindbrain, which then induce changes in body state that feed back to the brain. Central VT infusions did not inhibit feeding, suggesting that this VT mechanism selectively affects appetitive social responses. Because VT projections to the hindbrain are highly conserved in vertebrates, influences on peripheral feedback processes like the one we have described in goldfish may reflect how VT affected simple social behaviors in ancestral vertebrates and thus preadapted members of this peptide family to play increasingly complex roles in social and emotional regulation in modern animals.     

Bone metastasis from ovarian cancer

We report a case of epithelial ovarian cancer, which presented with lumbar vertebral metastasis soon after treatment, as a part of distant spread. This patient was then treated by palliative radiotherapy and put on second line chemotherapy i.e, Topotecan. She responded to treatment well.     

Effects of electrical stimulation in C2C12 muscle constructs

Electrical stimulation affects the deposition of extracellular matrices and cellular differentiation. Type I collagen is one of the most abundant extracellular matrix proteins; however, not much is known about the effects of electrical stimulation on collagen type I deposition in C2C12 cells. Thus, we studied the effects of electrical voltage and stimulation frequency in 3D cultured C2C12 muscle cells in terms of metabolic activity, type I collagen deposition and cell morphology. Electrically excitable C2C12 muscle cells were seeded in collagen scaffolds and stimulated with rectangular signals of voltage (2, 5, 7 V) and frequency (1, 2 Hz), using parallel carbon electrodes spaced 1 cm apart. Metabolic activity was quantified by the glucose:lactate concentration ratio in the medium. Apoptotic activity was assessed by TUNEL staining and changes in collagen deposition were identified by immunohistology. The ultrastructure of the tissue was examined by TEM. Glucose and lactate analysis indicated that all groups had similar metabolic activity. TUNEL stain showed no significant difference in apoptotic damage induced by electrical stimulation compared to the control. Samples stimulated at 2 Hz exhibited reduced collagen deposition compared to the control and 1 Hz stimulated samples. Muscle-protein marker desmin was highly expressed in constructs stimulated with 1 Hz/5 V sample. TEM revealed that the stimulated samples developed highly organized sarcomeres, which coincided with improved contractile properties in the 1 Hz/5 V- and 2 Hz/5 V-stimulated groups. Our data implicate that a specific electrical frequency may modulate type I collagen accumulation and a specific voltage may affect the differentiation of muscle sarcomeres in excitable cells.