Absorption,effectiveness and side effects of highly purified porcine NPH-insulin preparations (Leo®)

Summary The clinical characteristics of highly purified porcine NPH-insulin (Insulin Retard RI^®) were investigated, including absorption from the subcutaneous tissue, blood glucose-lowering effect, stability of mixtures of NPH and regular insulin and measurement of circulating porcine proinsulin and insulin antibodies in diabetics. The absorption of NPH-insulin followed first order kinetics. The half time was 6.9±2.6 h, with an intraindividual coefficient of variation of 26% and an interindividual coefficient of variation of 55%. After 24 h 90% of the injected insulin had disappeared from the subcutaneous tissue. The plasma insulin concentration was maximal 4–5 h after the injection and 24 h after the injection it was not significantly higher than before the injection. The blood glucose-lowering effect was significant 2.5 h after subcutaneous injection of NPH-insulin and was maximal after 5.5 h. The blood glucose-lowering effect of a pre-prepared mixture of 70% NPH and 30% regular insulin was not significantly different from the effect of 70% NPH and 30% regular insulin injected separately, which indicates the stability of mixtures of NPH and Regular insulin. Porcine proinsulin disappeared from the serum of patients switched to treatment with highly purified porcine NPH insulin and the insulin antibody titer fell. It was concluded that insulin Retard RI^® has a well-defined, reproducible effect with a clinically useful time course.With the technical assistance of Birthe Lørup, Hanne Richter-Olesen, and Knud Jørgensen, Finsen Laboratoriet, Copenhagen, Denmark.     

Pig xenografts to the immunocompetent rat brain: Survival rates using distinct neurotoxic lesions in the nigrostriatal pathway and two rat strains

Porcine foetal neurons for xenotransplantation in Parkinson's disease (PD) is an alternative source to human fetuses. One of the obstacles facing brain xenotransplantation is the existence of an immune response, which prevents long-term graft survival. Experimental results concerning the survival time of porcine foetal neurons implanted into the brain of immunocompetent rats have been quite different from one study to another, suggesting an effect on graft survival of uncontrolled experimental parameters. To identify such parameters, we have first analyzed the survival of porcine foetal nigral neurons at 5 and 10 weeks after implantation into the striatum of immunocompetent rats having different types of brain lesion affecting cells (quinolinic acid) or projections to the striatum (MPP+, 6-OHDA). In a second experiment, graft survival was analyzed in two strains of recipient rats (female Sprague-Dawley and male Lewis rats) in conditions of ipsilateral dopaminergic denervation using 6-OHDA. The characteristics of surviving grafts were assessed by measuring the graft volume, the number of TH+ neurons, the size of TH+ neurons soma, and CD5+ cell infiltration. Long-term survival (> or = 10 weeks) of porcine neurons could be observed in all experimental models. However, there was no significant difference in graft survival rates and characteristics of the surviving grafts between the lesioned groups, or between Sprague-Dawley and Lewis rats. Altogether, results were highly variable within groups of grafts exposed to similar experimental procedures at both 5 and 10 weeks post-grafting. We conclude that the distinct neurotoxins and host rat strains used in our experimental design are not major factors influencing the rejection time-course of primary neural xenografts.     

Intrathecal xenogeneic chromaffin cell grafts reduce nociceptive behavior in a rodent tonic pain model

Adrenal medullary chromaffin cells synthetize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides. Previous reports have shown that implantation of chromaffin cells into the spinal subarachnoid space can reduce both acute and chronic pain in several animal models. We recently demonstrated that human chromaffin cell grafts in the cerebrospinal fluid (CSF) could alleviate intractable cancer pain after failure of systemic opiates. However, wider application of this approach was limited by the limited availability of allogeneic donor material. Alternatively, chromaffin cells from xenogeneic sources such as bovine adrenal medulla were successful in the experimental treatment of pain, but recent concern over risk of prion transmission precluded use of bovine grafts in human clinical trials. The objective of the present study was to investigate the possibility of developing a new xenogeneic porcine source of therapeutic chromaffin cells because this strategy is currently considered the safest for transplantation in man. In the present study, we report the isolation and the characterization of primary porcine chromaffin cells (PCC) compared to bovine cells. We show, for the first time, that these cells grafted in the rat subarachnoid space can attenuate pain-related behaviors as assessed by the formalin test, a model of tonic pain. Moreover, in addition to behavioral studies, immunohistochemical analysis revealed robust survival of chromaffin cells 35 days after transplantation. Taken together, these results support the concept that porcine chromaffin cells may offer an alternative xenogeneic cell source for transplants delivering pain-reducing neuroactive substances.     

Expandable Bioresorbable Endovascular Stent. I. Fabrication and Properties

A bioresorbable, expandable poly(L-lactic acid) stent has been designed, based on a linear, continuous coil array principle, by which multiple furled lobes convert to a single lobe upon balloon expansion, without heating. Stent strength and compliance are sufficient to permit deployment by a conventional balloon angioplasty catheter. Several multiple lobe configurations were investigated, with expansion ratios ranging from 1.4 to 1.9 and expanded diameters ranging from 2.3 to 4.7 mm. Compression resistance of the expanded stent is dependent on fiber coil density and fiber ply. A range sufficient for endovascular service was obtained, with less than 4% elastic recoil in six day saline incubation studies. Surface plasma treatment with di(ethylene glycol) vinyl ether significantly reduced platelet adhesion in a 1 h porcine arteriovenous shunt model. Patency was maintained in one week implant studies in the porcine common femoral artery. However, a strong inflammatory response, and significant reduction of the vascular lumen were observed following two weeks implantation. The design principles and fabrication techniques for this bioresorbable stent are sufficiently versatile that a broad range of applications can be addressed. Much work remains to be done, including long-term evaluation of the inflammatory response, and of polymer degradation. The results of this study demonstrate the feasibility of expandable biodegradable stent design and deployment by conventional means. © 2003 Biomedical Engineering Society. PAC2003: 8768+z, 8719Uv     

Porcine Dermal Collagen (Permacol) for Facial Contour Augmentation: Preliminary Report

Soft tissue loss or damage can occur for various reasons, including trauma, surgery, and disease. Reconstruction of normal contours can be achieved by using either alloplastic implants or autogenous tissues. Permacol, a dermal replacement material derived from fibrous acellular porcine dermal collagen, has been used for restoration of soft-tissue contours in the face. Eight patients were treated with porcine collagen in an attempt to achieve a smooth contour and a natural feel. Clinically visible soft tissue defects were successfully covered and aesthetic results were satisfying. Transient swelling that subsided within a week was noted in all patients. Meticulous and aseptic technique is mandatory for Permacol use. With this limited experience, Permacol was successfully used as a filler implant in reconstruction of post-traumatic soft-tissue defects, correcting post-parotidectomy hallowing and secondary nasal surgery to cover osseocartilaginous irregularities. However, there is a potential risk of inflammation and skin contractures in thin-skinned patients when implants are placed superficially.     

"Porcine bronchus" diagnosed in neonatal period

“Porcine bronchus” is a right upper lobe bronchus arising directly from the trachea. This is an infrequent congenital abnormality and it usually represents the displaced origin of a normal bronchus. We herewith report a case of a child who was diagnosed to have tracheal bronchus in neonatal period and followed subsequently until 13 months of age.     

Characterisation of elastin and collagen in aortic bioprostheses

Porcine aortic valves used as cardiac valve bioprostheses are well adapted to physiological functions in the short term, but they lack long-term durability. Several multi-step extractions have been performed to obtain a perfectly acellular matrix. A new physical methodology is proposed to evaluate the resulting fibrous protein damage after biochemical extraction (TRI-COL and SDS). Thermal analysis techniques are adapted to collagen and elastin characterisation in the solid state. The aortic tissue thermal transitions are determined by differential scanning calorimetry (DSC): elastin glass transition is observed around 200°C, and collagen denaturation is observed around 230°C. These parameters are characteristic of the elastin network arrangement and of collagen triple-helix stability. The technique of thermostimulated currents (TSC) is well suited to specify the chain dynamics of proteins. The lowtemperature relaxations observed in both collagen and elastin are associated with localised motions, whereas the high-temperature modes are attributed to more delocalised motions of the chains. Therefore TSC and DSC spectrometries allow physical parameters specific to collagen and elastin to be obtained and their interaction in aortic tissues to be determined. According to the significant evolution of these parameters on SDS samples, the destabilising effect of this detergent is highlighted.     

Design and validation of immunological tests for the detection of Porcine endogenous retrovirus in biological materials

The present study details the design and demonstrates function for a series of reagents and methods to allow the detection of exposure to antigens specific for Porcine endogenous retrovirus (PERV). The detection of PERV is carried out by the means of a variety of immunological screening methods including, indirect immunofluorescence, Western blotting and enzyme linked immunosorbent assay (ELISA) for the detection of antibodies in serum specific for PERV gag and env antigens. Alternatively, PERV-specific antisera for gag and env can be used to detect viral antigen in serum or other samples. PERV env peptides with potential specificity for the known PERV types are also described. Antisera against the peptides can be used to detect PERV antigens directly or to characterise viral type. Using electron microscopy coupled with labelled PERV-gag-specific antisera it was possible to visualise PERV virions.     

Investigation of mezlocillin disposition with a porcine model

The suitability of the pig as an animal model for mezlocillin disposition was assessed. Serum, urine, and bile were collected after the administration of 50, 100 and 200 mg kg-1 mezlocillin to pigs and drug pharmacokinetics were characterized. Mezlocillin concentrations in biological fluids were determined by HPLC and free mezlocillin was determined by ultrafiltration. The pharmacokinetics of mezlocillin appeared to be independent of dose over the dosage range studied. Total clearance, renal clearance, and biliary clearance were 0.18 (0.05) 1 h-1 kg-1, 0.13 (0.03) 1 h-1 kg-1, and 0.07 (0.02) 1 h-1 kg-1, respectively. The steady-state volume of distribution was 0.29 (0.08) 1 kg-1. The pharmacokinetic parameters determined in the porcine model are similar to those reported for health human volunteers. Therefore, this model appears suitable for the study of mezlocillin disposition, and may be applied to the study of other agents that are appreciably biliary excreted.     

Dual expression system for assembling phage lambda display particle (LDP) vaccine to porcine Circovirus 2 (PCV2)

The bacteriophage lambda small capsid protein D forms trimers on the phage head. D-fusion polypeptides can be expressed from plasmids in E. coli and remain soluble without aggregation. We report a dual expression system for the display of four immunodominant regions of porcine Circovirus 2 (PCV2) capsid protein (CAP) as D-CAP fusions on lambda display particles (LDP). The LDP-D-CAP preparation proved an effective vaccine in pigs, eliciting both cellular and humoral immune responses and PCV2 neutralizing antibodies. In our dual system wild type D expression was encoded by a heteroimmune infecting phage. The D-fusion protein expression in the infected cells was from an inducible plasmid, enabling the deferral of D-fusion expression until needed. The effective vaccine preparation depended upon the gradient purification of very high concentration, essentially tail-less display particles, not previously described.