Effect of bombesin and cholecystokinin on plasma immunoreactive trypsin in humans

Since bombesin is a potent stimulus of the release of cholecystokinin (CCK), it has been suggested that the stimulatory effect of bombesin on pancreatic enzyme secretion is mediated by CCK. The present study was undertaken to determine the role of CCK in the bombesin-induced stimulation of plasma immunoreactive trypsin. Plasma CCK was measured by radioimmunoassay using the antibody T204, which binds to all biologically active sulfated COOH-terminal CCK-peptides. Plasma trypsin was also measured by radioimmunoassay. Infusion of 5 ng/kg/min bombesin in 6 healthy volunteers increased plasma CCK from 1.2 +/- 0.2-8.9 +/- 0.7 pM (p less than 0.0001). The peak increment in plasma CCK during bombesin (9.3 +/- 0.6 pM) was accompanied by a significant rise in plasma trypsin from 206 +/- 21-334 +/- 44 ng/ml (p less than 0.01). However, when similar increases in plasma CCK were achieved by infusion of 0.018 CU/kg/min CCK-33 (9.9 +/- 0.8 pM) or by intraduodenal instillation of 250 ml 20% Intralipid (9.7 +/- 1.9 pM), no significant changes in plasma trypsin were observed. It is therefore concluded that the stimulatory effect of bombesin on plasma immunoreactive trypsin is not mediated by CCK.     

Porous implants for knee joint meniscus reconstruction: a preliminary study on the role of pore sizes in ingrowth and differentiation of fibrocartilage

Implants with four different macropore sizes were implanted in the meniscus of 29 rabbits for assessment of ingrowth and differentiation of fibrocartilage. Implant macropores were 50-90, 90-150, 150-250 and 250-500 mum, the vol.% macropores was 48-55 and total pore volume 84-86 vol.%. Ingrowth was optimal in the two large pore implants whereas the small pore implants partially remained empty up to 1 year post-operative. Capsule formation and the foreign body reaction was severe for the small pore implants whereas this occurred to a lesser extent in the two large pore implants. Fibrocartilage formation, as assessed by morphology and antibody labelling for type I and type II collagen, was observed in a similar way in all implant types. It is concluded that for optimal ingrowth and incorporation of partial or total meniscal prosthesis, macropore sizes must be in the range of 150-500 mum.     

The Octopus Study: rationale and design of two randomized trials on medical effectiveness, safety, and cost-effectiveness of bypass surgery on the beating heart

The Octopus Study consists of two multicenter randomized clinical trials in which coronary artery bypass grafting on the beating heart (off-pump CABG) using the Utrecht Octopus Method is compared to intracoronary stent implantation and conventional CABG. The primary endpoint in the comparison of off-pump CABG versus stent implantation (OctoStent Trial) is medical effectiveness (i.e., absence of reintervention and major adverse cardiac and cerebrovascular events at 1 year after treatment). The primary endpoint in the comparison of off-pump CABG versus conventional CABG (OctoPump Trial) is cerebral safety (i.e., absence of cognitive deficits and cerebrovascular events at 3 months after treatment). Secondary endpoints in both trials include presence and severity of angina, quality of life, exercise capacity, and cost-effectiveness. A total of 560 patients will be enrolled. A random sample of 210 patients will undergo repeat angiography at 1 year to assess angiographic restenosis rate and graft patency. Including 1-year follow-up, the study will last for 3 years. Control Clin Trials 2000;21:595-609     

Resistance to antimicrobial peptides and stress response in Mycoplasma pulmonis

Antimicrobial peptides are widely distributed in nature, and in vertebrates, they play a key function in the innate immune defense system. It is generally agreed that these molecules may provide new antibiotics with therapeutic value. However, there are still many unsolved questions regarding the mechanisms underlying their antimicrobial activity as well as the mechanisms of resistance evolved by microorganisms against these molecules. The second point was addressed in this study. After determining the activity of 10 antimicrobial peptides against Mycoplasma pulmonis, a murine respiratory pathogen, the development of resistance was investigated. Following in vitro selection using subinhibitory concentrations of peptides, clones of this bacterium showing increased resistance to melittin or gramicidin D were obtained. For some of the clones, a cross-resistance was observed between these two peptides, in spite of their deep structural differences, and also with tetracycline. A proteomic analysis suggested that the stress response in these clones was constitutively activated, and this was confirmed by finding mutations in the hrcA gene; in mycoplasmas, bacteria which lack alternative sigma factors, the HrcA protein is supposed to play a key role as a negative regulator of heat shock proteins. By complementation of the hrcA mutants with the wild-type gene, the initial MICs of melittin and gramicidin D decreased to values close to the initial ones. This indicates that the resistance of M. pulmonis to these two antimicrobial peptides could result from a stress response involving HrcA-regulated genes.     

Comparison of three retroviral vector systems for transduction of nonobese diabetic/severe combined immunodeficiency mice repopulating human CD34+ cord blood cells

The use of recombinant vectors based on wild-type viruses that are absent in humans and are not associated with any disease in their natural animal hosts or in accidentally infected humans would add an additional level of safety for human somatic gene therapy approaches. These criteria are fulfilled by foamy viruses (FVs), a family of complex retroviruses whose members are widely found among mammals and are apathogenic in all hosts. Here, we show by comparison of identically designed vector constructs that recombinant retroviral vectors based on FVs were as efficient as lentiviral vectors in transducing nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice repopulating human CD34(+) cord blood (CB) cells. The FV vector was able to achieve gene transfer levels up to 84% of engrafted human cells in a short overnight transduction protocol. In contrast, without prestimulation of the target cells, a human immunodeficiency virus type 1 (HIV-1)-based lentiviral vector pseudotyped with gibbon ape leukemia virus envelope (GALV Env) was nearly as inefficient as murine leukemia virus (MLV)-based oncoretroviral vectors in transducing NOD/SCID repopulating cells. The same HIV vector pseudotyped with the vesicular stomatitis virus glycoprotein G (VSV-G) achieved high marking efficiency. Clonality analysis of bone marrow samples showed oligoclonal hematopoiesis with single to multiple insertions per cell, both for FV and HIV vectors. These data demonstrate that vectors based on FVs warrant further investigation and development for medical use.