New molecular approaches to tissue typing.
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Amino Acid Sequence↗
Biomedical subjects
J A Wade
Publications and source records attributed to J A Wade.
Regeneration across preserved peripheral nerve grafts.
The potential to store nerve grafts for a prolonged period of time was assessed in a rat sciatic nerve model. Three-centimeter syngeneic nerve grafts were stored in Belzer/University of Wisconsin cold storage solution at different temperatures (5 degrees C, 22 degrees C, or 37 degrees C) for varying time periods (6 h, 24 h, or 3 weeks) prior to transplantation. Functional assessment using serial walking track analyses revealed no difference between storage times and temperatures. At 14 months postengraftment, the conduction velocities and the number of myelinated fibers that had regenerated across all grafts stored at 5 degrees C for all time periods tested were superior to grafts stored at either 22 degrees C or 37 degrees C. Nerve grafts stored for up to 3 weeks at 5 degrees C acted as effective conduits for proximal regenerating fibers and resulted in histologic, electrophysiologic, and functional results equivalent to fresh nerve grafts. Nerve graft storage may be applicable to nerve allografts and potentially provide allograft material that requires reduced or no associated host immunosuppression.
Action Potentials↗
Phenotypic analysis of migrant, efferent lymphocytes after implantation of cold preserved, peripheral nerve allografts.
Cold-preservation of peripheral nerve allografts in vitro (3 weeks, 5 degrees C) was performed to determine its effect on local lymphocyte migration patterns in vivo. Lymphocyte migration was assessed by continuously monitoring the cell output in the regional lymph for nearly 1 month. Cold-preservation delayed or prevented the typical biphasic increase in efferent lymphocyte output observed after fresh allograft implantation. It also decreased the output of activated lymphocytes (CD 5 and MHC class II positive) compared with that seen in the fresh allograft response. These changes suggest that the host immune response to preserved nerve allografts is altered over a prolonged period in vivo (3 weeks). Cold-preservation may be a useful method of reducing allograft immunogenicity, thereby limiting systemic immunosuppression requirements for the successful clinical utilization of peripheral nerve allografts.
Animals↗
Primary sclerosing cholangitis in 32 children: clinical, laboratory, and radiographic features, with survival analysis.
The clinical presentation and outcome of 32 children with primary sclerosing cholangitis (PSC) are reviewed, the largest North American series. The majority of patients were diagnosed in their second decade (median age: 13 years). Four children presented before the age of 2 years, but none in the neonatal period. Seventeen patients had inflammatory bowel disease (IBD), all with colitis, 14 ulcerative colitis, and 3 Crohn's disease. Eight patients presented with chronic liver disease before clinical onset of IBD. Only 8 of 32 patients were jaundiced at presentation. Fifteen of 32 had a normal serum alkaline phosphatase (ALP) level at presentation. Nine children presented with features similar to those of autoimmune hepatitis. Cholangiography was performed in all cases and classified by a scoring system specifically developed for pediatric patients. Intrahepatic disease predominated; in only three cases a common bile duct stricture was identified requiring stenting. Findings on the initial liver biopsy were classified according to Ludwig's criteria for staging PSC: there were 15 biopsies in stages 1 to 2 and 17 biopsies stages 3 to 4. HLA class I and II antigens were determined in 27 patients. An increased incidence of HLA B8 and DR2(15) but not DRw52a (DRB3*0101) was found. Anti-neutrophil cytoplasmic antibody (ANCA) was positive in 10 of 24 patients tested. Survival analysis indicated that a later age at presentation, splenomegaly, and prolonged prothrombin time (PT) at presentation were significant contributors to the prediction of poor outcome (i.e., death or listing for transplantation). Liver transplantation was successfully performed in seven children. Physicians must maintain a high index of suspicion of PSC in any child or young adult presenting with chronic liver disease, especially in the presence of IBD, even with a normal serum alkaline phosphatase level.
Adolescent↗
Investigating the genetic basis for ankylosing spondylitis. Linkage studies with the major histocompatibility complex region.
OBJECTIVE: To assess the hypothesis that B27 or a gene(s) in close proximity (e.g., within or near the major histocompatibility complex [MHC]) represents a disease-causing ankylosing spondylitis (AS) gene, and therefore contributes directly to the pathogenesis of this disorder. METHODS: MHC haplotypes were determined by both serologic and molecular analyses in 15 multiple-case AS families from Toronto and Newfoundland. Segregation of MHC haplotypes with AS within these families was examined by linkage and identity-by-descent analyses. Attributable risk estimates for various genetic markers and for sex were calculated. RESULTS: Linkage analyses established significant linkage between AS and the MHC, the maximal logarithm of odds (LOD) score being 3.48 at a recombination frequency (O) of 0.05. In a second analysis in which the population association of the MHC gene HLA-B27 with AS was taken into account, the maximal LOD score was 7.5 at O = 0.05. Identity-by-descent analyses showed a significant departure from random segregation among affected avuncular (P < 0.05) and cousin (P < 0.01) pairs. The presence of HLA-B40 in HLA-B27 positive individuals increased the risk for disease more than 3-fold, confirming previous reports. Disease susceptibility modeling suggested an autosomal dominant pattern of inheritance, with penetrance of approximately 20%. CONCLUSION: These data provide the first conclusive demonstration of linkage between the MHC region and AS, and confirm that genes within this region contribute directly to the genetic susceptibility for AS.
Adolescent↗
Isometric contractile function following nerve grafting: a study of graft storage.
In order to assess the effects of storage on nerve grafts, the isometric contractile function of the gastrocnemius muscle was assessed 14 months following sciatic nerve autografting in the rat. Three-centimeter sciatic nerve grafts were stored at either 5 degrees C or 22 degrees C for 6 h, 24 h, or 3 weeks in an organ transplant solution. Muscle mass and maximal force in the fresh control graft group returned to 47% and 36% of normal levels, respectively, which was similar to stored grafts. Storage at 5 degrees C was superior to 22 degrees C and there was no decrement in contractile function in grafts stored up to 3 weeks at 5 degrees C. These findings suggest that the storage of nerve grafts is a feasible technique that might be applied to nerve allografts, thus permitting elective reconstruction of large peripheral nerve gaps.
Analysis of Variance↗
Effect of cold preservation on lymphocyte migration into peripheral nerve allografts in sheep.
Lymphocyte migration into fresh and preserved peripheral nerve allografts was quantitated to assess the effect of cold preservation and freeze-thawing pretreatment on the local immunological response to nerve allografts. Out-bred ewes received multiple 1.5-cm subcutaneous heterotopic peroneal nerve autografts, fresh allografts, and pretreated allografts, implanted within the same recipient. Lymphocyte migration was studied at 7 days by injecting autologous 111indium-labeled lymphocytes intravenously. After 3 hr of recirculation, lymphocyte migration into graft tissue was quantitated by a gamma counter (epm/g, mean +/- SEM). Lymphocyte traffic into fresh nerve allografts (21,623 +/- 3783) increased an average 9.4-fold over the autograft value (2918 +/- 377, P < 0.04). Histologic studies illustrated a marked lymphocytic infiltrate of CD4+ and CD8+ cells and enhanced class I and II MHC expression in fresh allografts, but not in autografts. Short-term cold preservation, for 6 and 12 hr (5 degrees C), enhanced lymphocyte entry into pretreated allograft tissue. Conversely, cold preservation for longer periods (1 and 3 weeks) dramatically reduced lymphocyte migration to values below corresponding autograft levels (783 +/- 100 and 1,252 +/- 120, respectively, P < 0.01). A comparable reduction in lymphocyte migration into nerve allografts was observed after freeze-thawing pretreatment (P < 0.01). Cold preservation of donor allogeneic lymphocytes inhibited their capacity to induce intradermal host lymphocyte migration, implicating passenger lymphocytes as a potential cold-sensitive allogeneic component of the nerve allograft. Assessment of the local response to ovine peripheral nerve allografts, utilizing radiolabeled autologous lymphocytes, demonstrated that cold preservation and freeze-thawing pretreatment significantly reduced lymphocyte migration into nerve allografts. The mechanism(s) of reduced lymphocyte migration may involve inactivation or death of antigen-presenting cells, including passenger lymphocytes.
Animals↗
Combinatorial diversity in DR2 haplotypes.
Sequence analysis has identified multiple alleles at two loci that encode for the DR2 specificity. The loci, DRB1 and DRB5, are in linkage disequilibrium which can extend to alleles of the DQ loci. Serologic, cellular, and sequence-specific oligonucleotide probe (SSOP) typing techniques have been used to identify the DR2 haplotypes. In this report, we have characterized by SSOP typing and cDNA/DNA sequence analyses the combinatorial diversity of DR2 haplotypes. Cells were selected on the basis of unique serologic reactivity, unique associations of alleles of DR and DQ loci, and/or presence in populations which have not been extensively characterized for HLA diversity. An asymmetric polymerase chain reaction (PCR) amplification was applied to rapidly screen unique cells and to characterize DNA sequence in conjunction with more conventional cDNA sequence analysis. The sequence data confirm the lack of a DRB5 locus in the DR2"LUM" specificity, the unexpected association of DRB1*1602 and DRB5*010 alleles in a nonCaucasoid population, and the association of the allele DRB1*1503 with DRB5*0101 in black African, African American and native American individuals. The DRB1*1503 and DRB5*0101 alleles were identified in an unusual haplotype, DR2,DQ2. The combinatorial diversity of the DR2 haplotypes is extended by these studies in nonCaucasoid populations.
Alleles↗
Temporary immunosuppression for peripheral nerve allografts.
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Analysis of Variance↗
Chronic cyclosporin A therapy in rats.
We investigated the pharmacokinetics of cyclosporin A (CsA) blood levels and drug toxicity in a chronic rat study in which long-term (30 weeks) CsA was administered. Ninety Lewis rats received subcutaneous CsA at 5 mg/kg/day for 12 weeks, at which time CsA injections were stopped in 50 animals. The remaining 40 rats were maintained on 5 mg/kg CsA daily until week 18 and then switched to an alternate day dosing until week 30. All rats were observed daily and weighed weekly. Whole blood CsA levels were determined by a commercially available radioimmunoassay kit. The daily dosing regimen resulted in greatly elevated trough CsA levels (greater than 1,600 micrograms/liter) and substantial chronic systemic toxicity, with weight loss and death in eight animals. Alternate day dosing reduced trough levels (mean 1,311 micrograms/liter) and decreased toxicity. Chronic administration by the subcutaneous route resulted in a considerable depot effect, with constancy of drug levels over a 48 hr dosing interval and a slow decline of drug levels (15 days) upon cessation of treatment. These results underscore the importance of monitoring both body weight and blood CsA levels in rodent studies when CsA is employed. Investigators should be aware of drug accumulation with chronic therapy and the consequent need to modify dosing to prevent toxicity.
Animals↗
Tissue matching: who needs it?
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Cadaver↗
Effects of incremental doses of alfentanil and propofol on the breathing of anaesthetized patients.
Incremental doses of alfentanil and propofol were given to anaesthetized healthy patients undergoing routine orthopaedic surgery. Ventilation was recorded by respiratory inductance plethysmography and analysed by microcomputer. Alfentanil affected primarily expiratory time. The onset of effect lasted 82 s (range 25-173 s); offset was exponential, with a half-life of 146 s (range 62-260 s). Alfentanil also reduced tidal volume, but the effect was less obvious and less consistent. Propofol affected primarily tidal volume. The onset of effect lasted 34 s (range 17-69 s); offset was linear, with a time to 50% recovery of 92 s (range 47-161 s). Propofol had little effect on expiratory time. The drugs had little effect on inspiratory time. Three patients showed periods when the distribution of expiratory times was bimodal; the mechanism for this is unknown.
Adult↗