Limitations of current diagnostic procedures for the diagnosis of Taenia solium cysticercosis in rural pigs

New evidence has been presented from our laboratory that the gliding bacterium, Myxococcus xanthus, does not home by chemotaxis toward a nutrient source. Our experiments, those of others, and the theory presented here combine to suggest a model, called the 'Pied Piper' model. It hypothesizes a gene that has a high mutation rate forward and back (say something in excess 10(-4) mutations per cell generation) which leads to switching between two motility states. Occasionally rare organisms become genetically, but reversibly, changed so that they move unidirectionally instead of mostly forward and back as do the bulk of the cells. When such a 'leader' cell arises, it continues to move in its original orientation, and causes a cohort of cells to move together away from the bulk of the cells. That is, in the less common mutational state it counteracts the usual tendency to just move forward and backward achieving little net movement. The assumption of a genetic element that mutates in a reversible way is suggested by numerous cases of reversible switches now known in a wide range of bacteria serving a variety of functions. A second aspect of the model is that mechanisms exist that cause cells to move in the same direction as their nearby neighbors. This process results in a regular spacing of bands of cells to form mounds in the absence of a leader. The action of C-factor, a factor-secreted by the cells which has been largely studied in the laboratory of Dale Kaiser, and extracellular fibrils, (rod-shaped protein and carbohydrate bodies) largely studied in the laboratory of Martin Dworkin, may be key elements in coordinating (or linking) the movements of neighboring cells. Based on the assumption of the absence of chemotaxis, computer simulations of pattern formation for gliding bacterial swarms and flares are consistent with observed behaviors and thus are additional evidence that chemotactic motility of the type exhibited by Escherichia coli, is not necessary for the group movements of M. xanthus. Some tests for this model are suggested.     

Primary bovine hepatocytes in the study of cytokine induced acute-phase protein secretion in vitro

OBJECTIVE: To determine placental transfer of ketanserin and to assess the effect of serotonin-2 receptor blockade by ketanserin on serotonin- and phenylephrine-induced vasoconstriction. STUDY DESIGN: Five chronically instrumented pregnant ewes at 120 days gestation were injected with 20 mg ketanserin i.v., and fetal and maternal arterial samples were obtained at predetermined intervals to assess placental transfer. Maternal and fetal responses of blood flows and pressures were determined after injected of serotonin (20 micrograms/kg) or phenylephrine (10 micrograms/kg) before and after ketanserin (0.75 mg/kg). RESULTS: In the ewe, ketanserin is transferred across the placenta and reaches measurable levels in the fetal lamb. Ketanserin blocks the maternal and fetal serotonin-induced rise in arterial pressure, but not the serotonin-induced reduction in uterine blood flow. CONCLUSION: In the pregnant ewe, the serotonin-induced rise in maternal and fetal blood pressure is effectively antagonized by ketanserin, whereas the serotonin-induced reduction in uterine blood flow is not.     

Regulation of antigen receptor signal transduction by protein tyrosine kinases

The purpose of this study was to assess the value of electron beam computed tomography in the detection of cardiac calcifications in coronaries and valves of dialysis patients and to determine the rate at which calcification progresses. Forty-nine chronic hemodialysis patients aged 28 to 74 years were compared with 102 non-dialysis patients aged 32 to 73 years with documented or suspected coronary artery disease, all of whom underwent coronary angiography. We used high-resolution electron beam computed tomography scanning to make 30 axial slices with a distance of 3 mm between each slice. The number of calcifications, the surface area, and the average and highest density values were measured. We calculated a quantitative coronary artery calcium score and assessed calcification of mitral and aortic valves. In dialysis patients, the measurements were repeated after 12 months. The coronary artery calcium score was from 2.5-fold to fivefold higher in the dialysis patients than in the non-dialysis patients. Hypertensive dialysis patients had higher calcium scores than non-hypertensive dialysis patients (P < 0.05). A stepwise, multiple regression analysis confirmed the importance of age and hypertension. No correlation between calcium, phosphate, or parathyroid hormone values and the coronary calcium score was identified; however, the calcium score was inversely correlated with bone mass in the dialysis patients (r = 0.47, P < 0.05). The mitral valve was calcified in 59% of dialysis patients, while the aortic valve was calcified in 55%. The coronary artery calcium score was correlated with aortic valvular, but not mitral valvular calcification. A repeat examination of the dialysis patients at an interval of 1 year showed a disturbing tendency for progression. Our data under-score the frequency and severity of coronary and valvular calcifications in dialysis patients, and illustrate the rapid progression of this calcification. Finally, they draw attention to hypertension as an important risk factor in this process.     

Cultural and psychological dimensions of human organ transplantation

As the 1997 Nurse in Washington Intern for SOHN, I was awed by the quality and quantity of information and experiences shared during the workshop. The three major concerns in healthcare policy on Capitol Hill are cost, quality, and access. Healthcare costs have escalated at tremendous speed, bypassing the growth of the Gross Domestic Product. Medicare is projected to go broke by 2007. The United States population is aging rapidly. The Federal Government must make changes to Medicare and Medicaid legislation or the U.S. Treasury may be consumed. As costs are cut, quality and access must be ensured. These are years of rapid change in healthcare. Nurses face many challenges and have many opportunities to participate in and influence the formation of healthcare policy. Nurses must be armed with information about key players, the processes, and what nursing can contribute to the healthcare system. We need to step up to the plate; we need to be part of the solution.     

Modeling of a three-dimensional structure of cytochrome P-450 1A2 and search for its new ligands

The substances inhibiting cytochrome P450 1A2 (CYP1A2) represent a perspective class of new drugs, which application in clinical practice can become the important part in preventive maintenance in oncology. The present work is devoted to computer modelling of 3-D structure of CYP1A2 and searching of new inhibitors by database mining. The modelling of CYP1A2 was done based on homology with 4 bacterial cytochromes P450 with known 3-D structure. For optimization of CYP1A2 active site structure the models of its complexes with characteristic substrates (caffeine and 7-ethoxyresorufin) were designed. These complexes were optimized by molecular dynamics simulation in water. The models of 24 complexes of CYP1A2 with known ligands with known Kd were designed by means of DockSearch and LeapFrog programs. 3D-QSAR model with good predictive force was created based on these complexes. On a final stage the search of knew CYP1A2 ligands in testing database (more than 23.000 substances from database Maybridge and 112 known CYP1A2 ligands from database Metabolite, MDL) was executed. 680 potential ligands of CYP1A2 with Kd values, comparable with known ones were obtained. This number has included 73 compounds from 112 known ligands, introduced in tested database as the internal control.     

Post-translational N-glycosylation of a truncated form of a peptide processing enzyme

Peptidylglycine alpha-amidating monooxygenase (PAM) catalyzes the carboxyl-terminal amidation of bioactive peptides through a two-step reaction involving the monooxygenase and lyase domains. PAM undergoes endoproteolytic cleavage in neuroendocrine cells in the lyase domain. To determine which of the two possible paired basic sites is utilized, truncated PAM proteins ending at these sites were stably expressed in Chinese hamster ovary cells. While characterizing the truncation mutants, it became apparent that N-glycosylation occurred post-translationally at the single site localized near the carboxyl terminus of the lyase domain. The post-translational N-glycosylation of this site does not require the newly synthesized protein to remain tightly bound to membranes. Both malfolded, secretion incompetent proteins and fully active, secreted proteins were subject to post-translational N-glycosylation.     

Adenovirus-mediated interleukin-10 gene transfer inhibits post-transplant fibrous airway obliteration in an animal model of bronchiolitis obliterans

Bronchiolitis obliterans, a form of chronic allograft rejection characterized by progressive fibrous obliteration of the airways, is the major obstacle limiting prolonged survival of lung transplant recipients. To date, no effective therapy against this fatal complication exists. Interleukin-10 (IL-10), an anti-inflammatory and immunosuppressive cytokine, inhibits various T cell and antigen-presenting cell functions. We examined the effect of IL-10 in an animal model for bronchiolitis obliterans. A heterotopic tracheal transplant model was used. IL-10 was administered to the recipient either in its recombinant form by osmotic minipump or by adenoviral-mediated IL-10 gene transfer (Ad5E1mIL-10). Successful gene transfection and expression was confirmed by measuring circulating IL-10 protein. Tracheal allografts were assessed histologically based on a scoring system. IL-10 administration (in recombinant form or by gene transfer) inhibited the development of fibrous airway obliteration 3 weeks after transplantation in comparison to untreated controls (p < 0.05). This was demonstrated only if the delivery was initiated 5 days after transplantation and not if it was started at the time of transplantation. A single administration of the gene construct was sufficient to achieve the desired effect. We have shown that IL-10 can prevent the development of airway fibro-obliteration in this model. Gene transfection at a site distant from a graft can be used to produce a desired effect on the graft. IL-10 may be of major importance in the control of post-transplant bronchiolitis obliterans. The timing of its administration is critical and further studies are required to determine the mechanisms underlying the observed effects of IL-10.     

ATP-dependent proteolysis in mitochondria. m-AAA protease and PIM1 protease exert overlapping substrate specificities and cooperate with the mtHsp70 system

To analyze protein degradation in mitochondria and the role of molecular chaperone proteins in this process, bovine apocytochrome P450scc was employed as a model protein. When imported into isolated yeast mitochondria, P450scc was mislocalized to the matrix and rapidly degraded. This proteolytic breakdown was mediated by the ATP-dependent PIM1 protease, a Lon-like protease in the mitochondrial matrix, in cooperation with the mtHsp70 system. In addition, a derivative of P450scc was studied to which a heterologous transmembrane region was fused at the amino terminus. This protein became anchored to the inner membrane upon import and was degraded by the membrane-embedded, ATP-dependent m-AAA protease. Again, degradation depended on the mtHsp70 system; it was inhibited at non-permissive temperature in mitochondria carrying temperature-sensitive mutant forms of Ssc1p, Mdj1p, or Mge1p. These results demonstrate overlapping substrate specificities of PIM1 and the m-AAA protease, and they assign a central role to the mtHsp70 system during the degradation of misfolded polypeptides by both proteases.     

Update on lumbar spinal stenosis. Retrospective study of 62 patients and review of the literature

Bactenecin 5 (Bac 5), a cationic antibacterial peptide, contains a repeating region of Arg-Pro-Pro-X (X = hydrophobic residue). To investigate the structure and property of a Pro/Arg-rich region, we synthesized a series of repeating peptides, Ac-(Arg-Pro-Pro-Phe)n-NHCH3 (n = 2, 4, 6, 8 and 10) (PR2, PR4, PR6, PR8 and PR10) as models. The circular dichroism (CD) study suggested that the peptides with longer repeats, PR6, PR8 and PR10, formed a conformation similar to poly(proline)-II in aqueous solution. The CD spectra did not change in the presence of dipalmitoyl-DL-alpha-phosphatidylcholine (DPPC), but they changed in the presence of DPPC/ dipalmitoyl-DL-3-phosphatidylglycerol (DPPG). The gamma-helix, which is very similar in conformation to the poly(proline)-II helix, had the lowest energy conformation for the peptides by energy calculations. Peptides PR6, PR8 and PR10 caused slight leakage of fluorescent dye entrapped in DPPC vesicles, and in the presence of DPPC/DPPG, these peptides showed a considerable level of dye-leakage activity. In contrast, the shorter peptides PR2 and PR4 showed no activity. The same tendency was found in measurements of membrane-fusion activity. Judging from these results, the repeating region of Bac 5 may make a framework to hold a conformation resembling the poly(proline)-II structure in aqueous solution. In addition, this region may interact with acidic lipids, resulting in a change in conformation of the peptide.