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R McKenna

Publications and source records attributed to R McKenna.

At least 19 recordsLinked to original sources
PubMed2004

Correlation between Neoral 2 hours post-dose levels and histologic findings on surveillance biopsies.

Use of 2-hour postdose (C2) monitoring has been a major step in optimizing immunosuppression following kidney transplantation, and extensive data has confirmed the superiority of C2 monitoring over the conventional trough monitoring (C0) in reducing the occurrence of acute rejection early after transplantation. In this retrospective study, we explored the relationship between Neoral pharmacokinetic parameters and the presence of subclinical rejections (ScRj). In the absence of acute rejection, lower C2 level was associated with more frequent episodes of ScRj. C0 monitoring was not predictive of AR, ScRj or any combinations thereof. Fast elimination in a subgroup of patients is not detected by the C0 and may lead to unnecessary increase of the drug dosage and increased risk of rejection.

Biopsy↗
PubMed2003

Initial closed operation of the CELSS Test Facility Engineering Development Unit.

As part of the NASA Advanced Life Support Flight Program, a Controlled Ecological Life Support System (CELSS) Test Facility Engineering Development Unit has been constructed and is undergoing initial operational testing at NASA Ames Research Center. The Engineering Development Unit (EDU) is a tightly closed, stringently controlled, ground-based testbed which provides a broad range of environmental conditions under which a variety of CELSS higher plant crops can be grown. Although the EDU was developed primarily to provide near-term engineering data and a realistic determination of the subsystem and system requirements necessary for the fabrication of a comparable flight unit, the EDU has also provided a means to evaluate plant crop productivity and physiology under controlled conditions. This paper describes the initial closed operational testing of the EDU, with emphasis on the hardware performance capabilities. Measured performance data during a 28-day closed operation period are compared with the specified functional requirements, and an example of inferring crop growth parameters from the test data is presented. Plans for future science and technology testing are also discussed.

Air Conditioning↗
PubMed2002

Identification of a novel HLA-B*07 allele--HLA-B*0726.

We describe here, the identification of a novel HLA-B*07 allele named HLA-B*0726. This allele was found in a Caucasian individual serologically typed as HLA-B7, B35. Novel DNA probe patterns for the HLA-B*07 allele were found using HLA-B specific reverse sequence-specific oligonucleotide probe (SSOP) and sequence-specific primer (SSP) typing. DNA sequencing demonstrated the presence of a new HLA-B*07 sequence variant encoding a single nucleotide substitution from a G to a T at nucleotide 539 in exon 3. This results in an amino acid substitution from arginine to leucine at residue 156 in exon 3.

Alleles↗
PubMed2001

Peritubular capillary basement membrane reduplication in allografts and native kidney disease: a clinicopathologic study of 278 consecutive renal specimens.

BACKGROUND: An association has been found between transplant glomerulopathy (TG) and reduplication of peritubular capillary basement membranes (PTCR). Although such an association is of practical and theoretical importance, only one prospective study has tried to confirm it. METHODS: We examined 278 consecutive renal specimens (from 135 transplants and 143 native kidneys) for ultrastructural evidence of PTCR. In addition to renal allografts with TG, we also examined grafts with acute rejection, recurrent glomerulonephritis, chronic allograft nephropathy and stable grafts ("protocol biopsies"). Native kidney specimens included a wide range of glomerulopathies as well as cases of thrombotic microangiopathy, malignant hypertension, acute interstitial nephritis, and acute tubular necrosis. RESULTS: We found PTCR in 14 of 15 cases of TG, in 7 transplant biopsy specimens without TG, and in 13 of 143 native kidney biopsy specimens. These 13 included cases of malignant hypertension, thrombotic microangiopathy, lupus nephritis, Henoch-Schonlein nephritis, crescentic glomerulonephritis, and cocaine-related acute renal failure. Mild PTCR in allografts without TG did not predict renal failure or significant proteinuria after follow-up periods of between 3 months and 1 year. CONCLUSIONS: We conclude that in transplants, there is a strong association between well-developed PTCR and TG, while the significance of mild PTCR and its predictive value in the absence of TG is unclear. PTCR also occurs in certain native kidney diseases, though the association is not as strong as that for TG. We suggest that repeated endothelial injury, including immunologic injury, may be the cause of this lesion both in allografts and native kidneys.

Basement Membrane↗
PubMed2001

Structural and kinetic analysis of the chemical rescue of the proton transfer function of carbonic anhydrase II.

Histidine 64 in human carbonic anhydrase II (HCA II) functions in the catalytic pathway of CO(2) hydration as a shuttle to transfer protons between the zinc-bound water and bulk water. Catalysis of the exchange of (18)O between CO(2) and water, measured by mass spectrometry, is dependent on this proton transfer and was decreased more than 10-fold for H64A HCA II compared with wild-type HCA II. The loss of catalytic activity of H64A HCA II could be rescued by 4-methylimidazole (4-MI), an exogenous proton donor, in a saturable process with a maximum activity of 40% of wild-type HCA II. The crystal structure of the rescued complex at 1.6 A resolution shows 4-MI bound in the active-site cavity of H64A HCA II, through pi stacking interactions with Trp 5 and H-bonding interactions with water molecules. In this location, 4-MI is about 12 A from the zinc and approximates the observed "out" position of His 64 in the structure of the wild-type enzyme. 4-MI appears to compensate for the absence of His 64 and rescues the catalytic activity of the H64A HCA II mutant. This result strongly suggests that the out conformation of His 64 is effective in the transfer of protons between the zinc-bound solvent molecule and solution.

Alanine↗
PubMed2001

Aboriginals with multiple sclerosis: HLA types and predominance of neuromyelitis optica.

BACKGROUND: MS is common in people of northern European ethnicity who live in northern geographic areas; however, MS is rarely identified among aboriginal peoples living in the same areas. OBJECTIVES: To determine the prevalence, clinical features, HLA type, and viral infections associated with MS among aboriginals in Manitoba, Canada. METHODS: A retrospective study was performed in which the clinical features of all aboriginal patients with MS together with HLA type and human herpesvirus-6, HIV-1, human T-cell lymphotropic virus-1, and endogenous retrovirus associated with MS (MSRV) infections were analyzed and compared with results from nonaboriginal patients with MS. RESULTS: Seven aboriginals with MS were identified with a period prevalence among aboriginals of 40:100,000. Clinical features included relapsing-remitting (n = 6) or primary progressive (n = 1) phenotypes with aggressive disease courses and frequent involvement of optic nerves and spinal cord (n = 5) compared with nonaboriginal patients. Autopsy of one patient showed necrosis and eosinophil infiltrates in a cervical spinal cord lesion and a demyelinated optic nerve. Analysis of HLA alleles at the DRB1 and DQB1 loci indicated that the HLA types detected were common in aboriginals, but there were no HLA alleles previously associated with the development of MS. Analysis of the copy number of MSRV did not show differences among aboriginals and nonaboriginals with or without MS. CONCLUSIONS: Aboriginals of Algonkian background are at increased risk for an aggressive type of MS, resembling neuromyelitis optica, which is resistant to conventional MS treatments and occurs independently of HLA alleles previously associated with MS.

Adult↗
PubMed2001

Structure of the Maize streak virus geminate particle.

The Geminiviridae is an extensive family of plant viruses responsible for economically devastating diseases in crops worldwide. Geminiviruses package circular, single-stranded DNA (ssDNA) genomes. The characteristic twinned or "geminate" particles, which consist of two joined, incomplete T = 1 icosahedra, are unique among viruses. We have determined the first structure of a geminivirus particle, the Nigerian strain of Maize streak virus (MSV-N), using cryo-electron microscopy and three-dimensional image reconstruction methods. The particle, of dimensions 220 x 380 A, has an overall 52-point-group symmetry, in which each half particle "head" consists of the coat protein (CP) arranged with quasi-icosahedral symmetry. We have modeled the MSV-N CP as an eight-stranded, antiparallel beta-barrel motif (a structural motif common to all known ssDNA viruses) with an N-terminal alpha-helix. This has produced a model of the geminate particle in which 110 copies of the CP nicely fit into the reconstructed density map. The reconstructed density map and MSV-N pseudo-atomic model demonstrate that the geminate particle has a stable, defined structure.

Amino Acid Sequence↗
PubMed2001

Characterization of the in vitro phosphorylation of human tau by tau protein kinase II (cdk5/p20) using mass spectrometry.

Hyperphosphorylated tau is an integral part of the neurofibrillary tangles that form within neuronal cell bodies, and tau protein kinase II is reported to play a role in the pathogenesis of Alzheimer's disease. Recently, we reported that tau protein kinase II (cdk5/p20)-phosphorylated human tau inhibits microtubule assembly, and tau protein kinase II (cdk5/p20) phosphorylation of microtubule-associated tau results in dissociation of phosphorylated tau from the microtubules and tubulin depolymerization. In the studies reported here, a combination of mass spectrometric techniques was used to study the phosphorylation of human recombinant tau by recombinant tau protein kinase II (cdk5/p20) in vitro. The extent of phosphorylation was determined by measuring the molecular mass of phosphorylated tau using mass spectrometry. Reaction of human recombinant tau with tau protein kinase II (cdk5/p20) resulted in the formation of two major species containing either five or six phosphate groups. The specific amino acid residues phosphorylated were determined by analyzing tryptic peptides by tandem mass spectrometry via either MALDI/TOF post-source decay or by electrospray tandem mass spectrometry. Based on these experiments, we conclude that tau protein kinase II (cdk5/p20) can phosphorylate human tau at Thr(181), Thr(205), Thr(212), Thr(217), Ser(396) and Ser(404).

Amino Acid Sequence↗
PubMed2001

Identification of aleutian mink disease parvovirus capsid sequences mediating antibody-dependent enhancement of infection, virus neutralization, and immune complex formation.

Aleutian mink disease parvovirus (ADV) causes a persistent infection associated with circulating immune complexes, immune complex disease, hypergammaglobulinemia, and high levels of antiviral antibody. Although antibody can neutralize ADV infectivity in Crandell feline kidney cells in vitro, virus is not cleared in vivo, and capsid-based vaccines have proven uniformly ineffective. Antiviral antibody also enables ADV to infect macrophages, the target cells for persistent infection, by Fc-receptor-mediated antibody-dependent enhancement (ADE). The antibodies involved in these unique aspects of ADV pathogenesis may have specific targets on the ADV capsid. Prominent differences exist between the structure of ADV and other, more-typical parvoviruses, which can be accounted for by short peptide sequences in the flexible loop regions of the capsid proteins. In order to determine whether these short sequences are targets for antibodies involved in ADV pathogenesis, we studied heterologous antibodies against several peptides present in the major capsid protein, VP2. Of these antibodies, a polyclonal rabbit antibody to peptide VP2:428-446 was the most interesting. The anti-VP2:428-446 antibody aggregated virus particles into immune complexes, mediated ADE, and neutralized virus infectivity in vitro. Thus, antibody against this short peptide can be implicated in key facets of ADV pathogenesis. Structural modeling suggested that surface-exposed residues of VP2:428-446 are readily accessible for antibody binding. The observation that antibodies against a single target peptide in the ADV capsid can mediate both neutralization and ADE may explain the failure of capsid-based vaccines.

Aleutian Mink Disease↗
PubMed2001

Tissue transglutaminase enzyme-linked immunosorbent assay as a screening test for celiac disease in pediatric patients.

OBJECTIVE: An immunoglobulin A (IgA) anti-tissue transglutaminase antibody assay (anti-tTG) was compared with the conventional IgA anti-endomysium antibody assay (EMA) to assess its reliability as a screening test for celiac disease (CD) in a pediatric population. METHODS: Seventy-five IgA-sufficient and 2 IgA-deficient children who were scheduled for small intestinal biopsy for the evaluation of history or symptoms suggesting a diagnosis of CD were prospectively evaluated and enrolled in this study (gastrointestinal [GI] patients). In addition, 16 children with type I diabetes mellitus (DM) who had a positive EMA and a small bowel biopsy were included as a separate cohort. IgA anti-tTG was measured by enzyme-linked immunosorbent assay (ELISA), and IgA-EMA titers were determined by indirect immunofluorescence on cryopreserved sections of monkey esophagus. RESULTS: Nine of the 75 IgA-sufficient GI patients had a small bowel biopsy consistent with the diagnosis of CD. Eight of 9 IgA-sufficient patients with a positive small bowel biopsy had positive anti-tTG and EMA tests. Four IgA-sufficient patients had a false-positive anti-tTG ELISA and 2 had a false-positive IgA-EMA assay. In the IgA-sufficient patients, the sensitivity was 89% and the negative predictive value was 98% for either assay. The specificities of the IgA anti-tTG and the IgA-EMA tests were 94% and 97%, respectively (not significant). The positive predictive value of the IgA anti-tTG was 67%, compared with 80% for the IgA-EMA (not significant). In the 2 IgA-deficient children, one of whom had biopsy-proved CD, both tests were negative. In the 16 DM children 12 true- and 4 false-positive IgA anti-tTG and IgA-EMA results were identified. Three of 12 complained of GI symptoms. In follow-up, thus far, none of the DM patients with a false-positive anti-tTG have developed CD. CONCLUSIONS: The IgA anti-tTG antibody assay is equivalent to the IgA-EMA assay as a screening test for CD in IgA-sufficient pediatric patients. Intestinal biopsy remains the gold standard for the diagnosis of CD.

Abdominal Pain↗
PubMed2000

A DNA-porphyrin minor-groove complex at atomic resolution: the structural consequences of porphyrin ruffling.

The crystal structure of a B-type DNA hexanucleotide duplex complexed with the porphyrin molecule nickel-[tetra-N-methyl-pyridyl] porphyrin has been solved by multiwavelength anomalous diffraction phasing and refined to an R factor of 11.5% at a resolution of 0.9 A. The structure has been solved and refined as two crystallographically independent duplexes, stacked end to end. Contrary to expectation, the porphyrin molecule is not intercalated into the duplex but is stacked onto the ends of the two-duplex stack. The porphyrin molecule is highly buckled as a consequence of the nickel coordination, which produces large changes in local DNA structure. A second mode of porphyrin binding is apparent as a consequence of crystal packing, which places the ligand in the minor groove of an adjacent duplex. This structure thus provides, to our knowledge, the first atomic visualization of minor-groove binding for a porphyrin molecule. The geometry of groove binding provides a ready explanation for porphyrin-induced DNA strand cleavage at deoxyribose residues.

Base Pairing↗
PubMed2000

Biochemical and physical characterization of parvovirus minute virus of mice virus-like particles.

The VP-2 major capsid protein of the prototype strain of the parvovirus minute virus of mice (MVMp) was expressed, using a baculovirus vector, in Sf9 insect cells. Immunogold electron microscopy of infected Sf9 cells showed VP-2 localized in the nucleus and cytoplasm as is observed in mammalian cells during natural infections. The VP-2 subunits self-assembled into empty parvovirus-like particles (VLPs), which appeared morphologically similar to and immunogenically indistinguishable from native empty MVMp particles, which also contain the minor capsid protein, VP1. Incubations under different pH and temperature conditions showed that the MVMp VLPs and native empty MVMp capsids share comparable stability. Once heated the particles can be similarly and specifically cleaved by trypsin at the VP-2 N-terminal domain. This process mimics the further maturation of the "rat-like" parvovirus virions, following viral DNA encapsidation, indicating that biologically relevant features of the MVMp capsid are maintained in the VLPs. Crystals have been obtained for the MVMp VLPs which were isomorphous to those used for the high-resolution structure determination of virions and native empty particles of the immunosuppressive strain of MVM (MVMi). The VLP crystals diffracted X rays to beyond 3-A resolution and are in space group C2 (a = 448.7, b = 416.6, c = 306.1 A, and beta = 95.9 degrees ). This is the first report of crystals from parvoviral particles produced in a heterologous system diffracting X rays to high resolution, indicating that VP-2 of some parvovirus capsids can self-assemble into ordered T = 1 icosahedral capsids in the absence of other viral and host cell functions.

Animals↗
PubMed1999

Comparison of COBE Spectra software version 4.7 PBSC and version 6.0 auto PBSC program.

Until recently, the collection of peripheral blood progenitor cells (PBPC) has been semi-automated by using the COBE Spectra, with the operator manually maintaining the position of the white cells being collected. The COBE Spectra Version 6.0 apheresis device offers the user an automated program for the collection of PBPC. In this study, we compared the new software Version 6.0 to that of Version 4.7. Patients (n = 46) undergoing PBPC collection were allocated to cell processing with either Version 4.7 (n = 24) or Version 6.0 (n = 22). The CD34+ cell count, mononuclear cell (MNC) count, white cell count (WCC), hemoglobin (Hb), and platelet content in the autograft product by using the two versions were compared. We divided the analysis into three subsets according to peripheral blood (PB) CD34 content: <10x10(6)/L, 10-50x10(6)/L and >50x10(6)/L. Analysis of the three subsets showed no statistical difference between results obtained when the starting PB CD34+ cell count was 10-50x10(6)/L (P=0.08) or >50x10(6)/L (P=0.4065). At lower starting PB CD34+ cell counts of <10x10(6)/L, Version 4.7 was superior (P=0.0167). However, autograft platelet contamination of the autograft was significantly higher using Version 4.7 (P=<0.0001).

Antigens, CD34↗
PubMed1999

Pulmonary artery pressure: an intraoperative guide to limiting resection volume.

Lung volume reduction surgery (LVRS) has shown promising results in severe emphysema. However, intraoperative indicators are needed to define optimal resection volumes. Diffusing capacity (DLCO) worsens with larger LVRS and may correlate with pulmonary artery (PA) pressure. We hypothesized that there would be a greater increase in PA pressures with larger volume LVRS in an inhaled elastase animal emphysema model. Twenty-one rabbits were induced with 15,000 units of elastase via an endotracheal tube. Four weeks later, bilateral LVRS was performed through a median sternotomy using an endoscopic stapler. PA pressures were measured prior to LVRS, immediately after LVRS, and at sacrifice. Single-breath DLCO, static pressure-volume relationships, and forced expiratory flows were measured prior to induction and at corresponding times to PA pressures. Systolic PA pressures increased in both groups immediately after LVRS (small: 2. 67 +/- 9.2 mm Hg, ANOVA, P = 0.023; large: 3.8 +/- 8.5 mm Hg, P = 0. 002), and then decreased at time of sacrifice 1 week later (small: 9. 43 +/- 4.8 mm Hg, ANOVA, P = 0.053; large: 5.2 +/- 7.3 mm Hg, P = 0. 552). The decrease, at sacrifice, in PA pressures was greater for small LVRS animals than large LVRS animals. The mortality rate (MR) for the small resection group was 0%, whereas that for the large resection group was 24%. The MR associated with larger LVRS was appreciably greater than that associated with small LVRS. These studies suggest that PA pressures may prove to be a useful intraoperative indicator for limits of resection.

Animals↗
PubMed1999

Diffusing capacity limitations of the extent of lung volume reduction surgery in an animal model of emphysema.

OBJECTIVE: The purpose of this study was to investigate in an elastase-induced emphysema rabbit model the effects of increasing resection volumes during lung volume reduction surgery on pulmonary compliance, forced expiratory air flow, and diffusing capacity to assess factors limiting optimal resection. METHODS: Emphysema was induced in 68 New Zealand White rabbits with 15,000 units of aerosolized elastase. Static respiratory system compliance, forced expiratory flow, and single-breath diffusing capacity were measured before the induction of emphysema, after the induction of emphysema, and 1 week after a bilateral upper and middle lobe lung volume reduction operation. RESULTS: Static respiratory system compliance with 60 mL insufflation above functional residual capacity increased with emphysema induction and then decreased progressively with resection of larger volumes of lung tissue (P =.001 by analysis of variance). Expiratory flow improved after lung resection in the rabbits with large resection volumes. In contrast, diffusing capacity tended to deteriorate with larger resection volumes (P =. 18). CONCLUSION: Improvements in respiratory system compliance and forced expiratory flow after lung volume reduction operations may account for the improvements seen clinically. Declines in diffusing capacity with extensive lung reduction may limit the clinical benefits associated with greater tissue resection volumes. Future investigations with animal models may reveal other physiologic parameters that may further guide optimal lung volume reduction procedures.

Animals↗
PubMed1999

Quantitation of allograft fibrosis and chronic allograft nephropathy.

Despite improvements in the prevention and treatment of acute renal allograft rejection, the long-term survival of renal transplants has not increased. Immunologic and non-immunologic factors contribute to the gradual deterioration of graft function and to the histologic lesion characterized by vascular and interstitial fibrosis ('chronic rejection'). Quantitation of this process has been attempted using various invasive and non-invasive methods. These methods, performed at different times post-transplant, are reviewed in this article. In particular, pathology scoring systems and the potential of using computerized image analysis of biopsy material are discussed.

Biopsy↗
PubMed1999

Antisense oligodeoxynucleotides targeting internal exon sequences efficiently regulate TNF-alpha expression.

ABSTRACT Exon sequences upstream of splice sites play a critical role in mRNA processing, which is dependent on spliceosome interactions with these sites. Using antisense oligodeoxynucleotides (ODN), we targeted these and other sequences of the proinflammatory tumor necrosis factor-alpha (TNF-alpha) gene because it is multiply spliced and has been difficult to regulate with ODN in the past. ODN targeting exon sequences upstream of the donor splice sites of internal exons 2 (ORF4) and 3 (ORF6) significantly reduced TNF-alpha levels in stimulated U937 cells by 62%+/-7% and 51%+/-9%, respectively, in a dose-dependent manner but did not affect interleukin-6 (IL-6) levels. In contrast, ODN targeting the exon sequences downstream of the acceptor splice sites of exons 1, 2, and 3 failed to reduce TNF-alpha levels significantly under the same conditions. End-phosphorothioated ORF4 (ORF4-PE) significantly reduced TNF-alpha mRNA levels by greater than 80% (p < 0.001) and protein levels by 60% (p < 0.001) in U937 cells. ORF4-PE reduced newly synthesized TNF-alpha protein levels by >80% in lipopolysaccharide (LPS)-stimulated human macrophages, by greater than 60% in phorbol myristate acetate/phyto-hemagglutinin (PMA/PHA)-stimulated human peripheral blood mononuclear cells (PBMC), and by approximately 50% in LPS-stimulated murine monocytes. These results suggest that exon sequences flanking donor splice sites are highly susceptible target domains for antisense inhibition of TNF-alpha gene expression.

Animals↗