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P D Wilson

Publications and source records attributed to P D Wilson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Modification of the composition of polycystin-1 multiprotein complexes by calcium and tyrosine phosphorylation.

Mutations in the PKD1 gene are responsible for >85% of autosomal dominant polycystic kidney disease (ADPKD). The protein product of PKD1, polycystin-1, is a large, modular membrane protein, with putative ligand-binding motifs in the extracelluar N-terminal portion, 9-11 transmembrane domains and an intracellular C-terminal portion with phosphorylation sites. A role for polycystin-1 as a cell surface receptor involved in cell-matrix and cell-cell interactions has been proposed. In this study, we have analyzed polycystin-1 and associated protein distribution in normal human epithelial cells and examined the role of cell-matrix versus cell-cell interactions in regulation of the assembly of polycystin-1 multiprotein complexes. Immunocytochemistry, sucrose density gradient sedimentation, co-immunoprecipitation analyses and in vitro binding assays have shown that polycystin-1 associates with the focal adhesion proteins talin, vinculin, p130Cas, FAK, alpha-actinin, paxillin and pp60c-src in subconfluent normal human fetal collecting tubule (HFCT) epithelia when cell-matrix interactions predominate. Polycystin-1 also forms higher S value complexes with the cell-cell adherens junction proteins E-cadherin, beta- and gamma-catenins in confluent cultures when cell-cell interactions are predominant. Polycystin-1 multiprotein complexes can be disrupted by cytochalasin D but not by colchicine, suggesting involvement of the actin cytoskeleton. Although inhibition of tyrosine phosphorylation by tyrphostin inhibits polycystin-1-FAK interactions, E-cadherin interactions are enhanced. High calcium treatment also increases polycystin-1-E-cadherin interactions.

Cadherins↗
PubMed2000

Microgradients in bacterial colonies: use of fluorescence ratio imaging, a non-invasive technique.

Fluorescence ratio imaging is a non-invasive technique for studying the formation of microgradients in immobilised bacterial colonies. These gradients can be quantified easily when combined with the gel cassette system designed at the Institute of Food Research, Norwich, UK. Colonies of Lactobacillus curvatus were observed using this technique and relevant pH gradients were present when the colonies reached a diameter of about 100 microm. These pH gradients were due to production of lactic acid by L. curvatus cells in the colonies. The spatial resolution of the images was about 1.5 microm (scale of bacterial cells) and therefore very suitable for observing local effects in colonies which ranged in sizes from 1 to 500 microm.

Bacteriological Techniques↗
PubMed2000

Monomeric midkine induces tumor cell proliferation in the absence of cell-surface proteoglycan binding.

Midkine (MK), a retinoic acid-inducible heparin-binding protein, is a mitogen which initiates a cascade of intracellular protein tyrosine phosphorylation mediated by the JAK/STAT pathway after binding to its high affinity p200(+)/MKR cell surface receptor in the G401 cell line [Ratovitski, E. A. (1998) J. Biol. Chem. 273, 3654-3660]. In this study, we determined the biophysical characteristics of purified recombinant murine MK and analyzed the requirements for ligand multimerization and cell surface proteoglycan binding for the G401 cell mitogenic activity of MK. Our studies indicate that the secreted form of MK (M = 13 kDa) exists in solution as an asymmetric monomer with a frictional coefficient of 1. 48 and a Stokes radius of 23.7 A. By constructing bead models of MK using the program AtoB and the program HYDRO to predict the hydrodynamic properties of each model, our data suggest that MK has a dumb-bell shape in solution composed of independent N- and C-terminal domains separated by an extended linker. This asymmetric MK monomer is a biologically active ligand with mitogenic activity on G401 cells in vitro. Neither heparin-induced formation of noncovalent MK multimers nor tissue transglutaminase II covalent multimerization of MK enhanced MK mitogenic activity in this system. Since neither heparin competition nor cell treatment with chondroitinase ABC or heparinase III abolished the mitogenic effects of MK on G401 cells, cell-surface proteoglycan binding by MK does not appear to be a requirement for its observed mitogenic effects. These results provide strong evidence that the MK-specific p200(+)/MKR has distinctive biochemical properties which distinguish it from the receptor tyrosine phosphatase cell-surface proteoglycan PTPzeta/RPTPbeta and support the hypothesis that the diverse biological effects of MK are mediated by multiple cell-specific signal transduction receptors.

Animals↗
PubMed2000

Formation of 20-hydroxyeicosatetraenoic acid, a vasoactive and natriuretic eicosanoid, in human kidney. Role of Cyp4F2 and Cyp4A11.

20-hydroxyeicosatetraenoic acid (20-HETE), an omega-hydroxylated arachidonic acid (AA) metabolite, elicits specific effects on kidney vascular and tubular function that, in turn, influence blood pressure control. The human kidney's capacity to convert AA to 20-HETE is unclear, however, as is the underlying P450 catalyst. Microsomes from human kidney cortex were found to convert AA to a single major product, namely 20-HETE, but failed to catalyze AA epoxygenation and midchain hydroxylation. Despite the monophasic nature of renal AA omega-hydroxylation kinetics, immunochemical studies revealed participation of two P450s, CYP4F2 and CYP4A11, since antibodies to these enzymes inhibited 20-HETE formation by 65. 9 +/- 17 and 32.5 +/- 14%, respectively. Western blotting confirmed abundant expression of these CYP4 proteins in human kidney and revealed that other AA-oxidizing P450s, including CYP2C8, CYP2C9, and CYP2E1, were not expressed. Immunocytochemistry showed CYP4F2 and CYP4A11 expression in only the S2 and S3 segments of proximal tubules in cortex and outer medulla. Our results demonstrate that CYP4F2 and CYP4A11 underlie conversion of AA to 20-HETE, a natriuretic and vasoactive eicosanoid, in human kidney. Considering their proximal tubular localization, these P450 enzymes may partake in pivotal renal functions, including the regulation of salt and water balance, and arterial blood pressure itself.

Antibodies↗
PubMed2000

Interrupted aortic arch: an epidemiologic study.

BACKGROUND: Interruption of the aortic arch (IAA) is a rare but severe anomaly associated with major intracardiac defects and with multisystem noncardiac malformations, recently linked to chromosome deletion of 22q11.2. METHODS: The Baltimore-Washington Infant Study (1981-1989), a population-based epidemiologic study of cardiovascular malformations, evaluated 53 infants with IAA in comparison with 3,572 controls. Risk factors for the anatomic subtypes were evaluated in 14 cases of IAA type A and 32 cases of IAA type B, but no molecular genetic tests were available. The distribution of associated cardiac defects was similar for both types. RESULTS: DiGeorge syndrome (DGS) occurred more frequently in IAA type B. Case-control comparisons demonstrated that infants in both groups were growth retarded at birth. A family history of noncardiac defects occurred only in IAA type B cases and included relatives with cleft lip and/or cleft palate. Candidate risk factors were associated only in type B cases and differed for those with (n = 10) and for those without (n = 19) DGS: a family history of noncardiac defects (odds ratio [OR] = 7.2, 95% confidence interval [CI] = 1.5-39.2) and maternal use of aspirin during the critical period (OR = 4.8, 95% CI = 1.3-25.4) occurred with DGS, while previous stillbirth (OR = 9.4, 95% CI = 1.3-53.1), bleeding during pregnancy (OR = 3.7, 95% CI = 1.4-11.4), and maternal exposure to arts/crafts paints (OR = 4.8, 95% CI = 1.3-17.4) were associated in those without DGS. CONCLUSIONS: These findings confirm the heterogeneity of IAA and of the type B subtype. Risk factors specific for cases with DGS may open a window to further investigations of the etiology of IAA and of the associated molecular genetic abnormalities.

Abnormalities, Multiple↗
PubMed2000

Colposuspension success and failure: a long-term objective follow-up study.

The Burch colposuspension is regarded as one of the most successful procedures for the operative treatment of genuine stress incontinence. In this study the authors have attempted to define long-term subjective and objective success rates. Of 121 patients operated on between 1985 and 1995, 83 were fully assessed: 77% (64/83) had no stress leakage, but 41% (34/83) were suffering from urge incontinence. On clinical assessment 6 cases of uterine prolapse or vault descent, 21 cystoceles (25%) and 47 rectoceles or rectoenteroceles (57%) were detected, all but 8 being asymptomatic. On ultrasound 64/83 patients (77%) had a normal result. Ten patients demonstrated bladder neck hypermobility and in 9 there was urethral funneling without hypermobility. Survival analysis showed that the likelihood of all types of failure and of abnormal ultrasound findings increased over time. It is proposed that long-term results after incontinence surgery be presented as survival analysis.

Adult↗
PubMed2000

Apical plasma membrane mispolarization of NaK-ATPase in polycystic kidney disease epithelia is associated with aberrant expression of the beta2 isoform.

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease of the kidney, characterized by cystic enlargement of renal tubules, aberrant epithelial proliferation, and ion and fluid secretion into the lumen. Previous studies have shown abnormalities in polarization of membrane proteins, including mislocalization of the NaK-ATPase to the apical plasma membranes of cystic epithelia. Apically located NaK-ATPase has previously been shown to be fully functional in vivo and in membrane-grown ADPKD epithelial cells in vitro, where basal-to-apical (22)Na transport was inhibited by application of ouabain to the apical membrane compartment. Studies were conducted with polymerase chain reaction-generated specific riboprobes and polyclonal peptide antibodies against human sequences of alpha1, alpha3, beta1, and beta2 subunits of NaK-ATPase. High levels of expression of alpha1 and beta1 messenger RNA were detected in ADPKD and age-matched normal adult kidneys in vivo, whereas beta2 messenger RNA was detected only in ADPKD kidneys. Western blot analysis and immunocytochemical studies showed that, in normal adult kidneys, peptide subunit-specific antibodies against alpha1 and beta1 localized to the basolateral membranes of normal renal tubules, predominantly thick ascending limbs of Henle's loop. In ADPKD kidneys, alpha1 and beta2 subunits were localized to the apical epithelial cell membranes, whereas beta1 was distributed throughout the cytoplasm and predominantly in the endoplasmic reticulum, but was not seen associated with cystic epithelial cell membranes or in cell membrane fractions. Polarizing, renal-derived epithelial Madin Darby canine kidney cells, stably expressing normal or N-terminally truncated chicken beta1 subunits, showed selective accumulation in the basolateral Madin Darby canine kidney cell surface, whereas c-myc epitope-tagged chicken beta2 or human beta2 subunits accumulated selectively in the apical cell surface. Similarly, human ADPKD epithelial cell lines, which endogenously expressed alpha1 and beta2 NaK-ATPase subunits, showed colocalization at the apical cell surface and coassociation by immunoprecipitation analysis. These results are consistent with a model in which the additional transcription and translation of the beta2 subunit of NaK-ATPase may result in the apical mislocalization of NaK-ATPase in ADPKD cystic epithelia.

Animals↗
PubMed2000

Primary total hip replacement with a noncemented acetabular component: minimum 5-year clinical follow-up.

The results of 123 total hip replacements with a noncemented Harris-Galante I acetabular component were reviewed (minimum 5-year clinical follow-up). The average clinical follow-up was 7 years (range, 5-10.8 years). No acetabular components were revised for loosening. One cup was revised for recurrent dislocation. In 3 cases, the acetabular liner was replaced at the time of femoral component revision (aseptic loosening), and in 1 case, a liner was revised because of recurrent dislocations. Of the hips, 92 had a complete set of radiographs for analysis. None of the acetabular components had migrated. Of the 92 acetabular components, 90 were considered radiographically stable (98%). Of these hips, 24 had linear radiolucencies of < or =2 mm in < or =2 of 4 zones and were considered stable. Two cups (2%) were considered possibly unstable. One of these had a linear radiolucent line in 3 zones, and the other had an osteolytic lesion measuring 6 x 11 mm in greatest dimensions. No acetabular components were definitely unstable. The average Harris Hip Score improved from 50 points (range, 17-89 points) preoperatively to 95 points (range, 74-99 points) at the latest follow-up examination. The average Hospital for Special Surgery hip score improved from 21 points (range, 10-31 points) preoperatively to 38 points (range, 27-40) at the last follow-up examination. Noncemented acetabular fixation with the Harris-Galante I component showed excellent clinical results at a minimum of 5 years' follow-up.

Arthroplasty, Replacement, Hip↗
PubMed2000

Development of a three-centre simultaneous objective structured clinical examination.

OBJECTIVE: To describe the development, organization, implementation and evaluation of a yearly multicentre, identical and simultaneous objective structured clinical examination (OSCE). SUBJECTS: All fifth-year medical students in a 6-year undergraduate medical programme. SETTING: The Christchurch, Dunedin and Wellington Schools of Medicine of the University of Otago, New Zealand. METHOD: One practice and two full 18-station OSCEs have been completed over 2 years, for up to 72 students per centre, in three centres. The process of development and logistics is described. Data are presented on validity, reliability and fairness. RESULTS: Face and content validity were established. Internal consistency was 0.83-0. 86 and interexaminer reliability, as assessed by the coefficient of correlation, averaged 0.78. Students rated the OSCE highly on relevance. Of the total variance in total OSCE marks, the schools contributed 6.9%, and the students 93.1%, in the first year. In the second year the schools contributed 6.2% and the students 93.8%. CONCLUSION: Implementation of a psychometrically sound, multicentre, simultaneous and identical OSCE is possible with a low level of interschool variation.

Clinical Competence↗
PubMed2000

Hospital for special surgery. A brief review of its development and current position.

On May 1, 1999, the Hospital for Special Surgery was 136 years old. To present a history that does adequate justice to the many people, who have been or still are involved in the making of it, is an impossible task. Nevertheless, this document is important because the hospital, first under the name of Ruptured and Crippled and then under that of Special Surgery has played such an important role in the development of orthopaedics and rheumatology in America during the past century. The reader must forgive an orthopaedic bias to this account and also realize the limitation of space that makes it at best fragmentary and incomplete. The account begins with a description of the hospital's current situation, physical layout and governance. A terse history of the hospital's origin and subsequent development follows, which includes a more specific description of the growth of its orthopaedic surgical services. Finally, separate records of the 112-year-old Postgraduate Orthopaedic Educational Program and 44-year-old Research Division are presented.

Education, Medical, Graduate↗
PubMed1999

Identification of phosphorylation sites in the PKD1-encoded protein C-terminal domain.

The PKD1-encoded protein, "polycystin-1", has a large N-terminal extracellular portion, multiple transmembrane domains, and a short intracellular C-terminal tail with four tyrosine residues and two putative sites for serine phosphorylation. Its function in kidney development and autosomal dominant polycystic kidney disease (ADPKD) is still unknown. We have subcloned the cDNA encoding the polycystin-1 C-terminal domain (PKD1-CTD) into a prokaryotic expression vector, and site-directed mutagenesis was performed to target the four tyrosine residues and four serine residues in two putative phosphorylation sites. In vitro phosphorylation assays were conducted on both wild type and mutant PKD1-CTD fusion proteins. It was found that the wild type PKD1-CTD and all mutant fusion proteins, except S4251G/S4252G, could be phosphorylated by lysates from cultured normal human renal collecting tubule (NHCT) cells, as well as by commercially purified cAMP-dependent protein kinase (PKA). The phosphorylation of the PKD1-CTD fusion protein by NHCT lysates was greatly enhanced by cAMP and its analog 8-Br-cAMP, and inhibited by the specific PKA inhibitors PKI(6-22) and H-89. Activators and inhibitors of protein kinase C (PKC) had no effects on the phosphorylation of the PKD1-CTD fusion protein. Using commercially purified pp60(c-src) (c-src) it was also shown that the PKD1-CTD fusion protein could be phosphorylated by c-src in vitro, and that this phosphorylation could be abolished by a mutation Y4237F. By comparing the amino acid sequence at 4249-4253 (RRSSR) with the consensus sequence for PKA phosphorylation (RRXSX), we suggest that the serine residue at 4252 is the target of phosphorylation by a cAMP-dependent protein kinase in NHCT cell lysates. In addition, we suggest that Y4237 might be phosphorylated by c-src in living cells.

Cells, Cultured↗
PubMed1999

WT1 expression induces features of renal epithelial differentiation in mesenchymal fibroblasts.

The WT1 tumor suppressor gene, implicated in hereditofamilial and sporadic Wilms' tumor, is required for normal renal development and is up-regulated during the mesenchymal-epithelial transition. NIH3T3 fibroblasts overexpressing WT1 were less proliferative, larger in size and more firmly attached to tissue culture plastic, suggesting an alteration of their state of differentiation. These cells were studied in vivo by subcutaneous injection into nude mice. The resulting tumors exhibited epithelioid histopathology and formed desmosome-like structures. Molecular analyses of these WT1 expressing fibroblasts grown in culture and in nude mice revealed significant alterations in the expression of many kidney epithelial markers. These studies indicate that WT1 expression can initiate features of a program of epithelial differentiation consistent with a prominent role for WT1 in the mesenchymal epithelial transition that occurs during renal development. Through this work we identified a number of novel target genes for the WT1 transcription factor, including uvomorulin, integrin alpha8 and perlecan, and suggest that WTI may activate the IGF-II gene, also implicated in the development of Wilms' tumor.

3T3 Cells↗
PubMed1999

The influence of bladder volume on the position and mobility of the urethrovesical junction.

The influence of bladder volume on the position, mobility and funneling of the bladder neck and proximal urethra was determined by transperineal ultrasound in a prospective comparative clinical study at Dunedin Hospital, Dunedin, New Zealand. One hundred and nine women underwent urodynamic assessment, either as part of the investigation of urinary incontinence or as follow-up after incontinence-correcting surgery. Bladder neck descent, retrovesical angle, rotation of the proximal urethra, and simple and extensive funneling/opening of the proximal urethra on Valsalva maneuver were assessed using ultrasound imaging at approximately 50 ml bladder volume and maximum bladder capacity (mean 355 ml, range 125-470 ml). The position of the bladder neck at rest was slightly higher at 50 ml than at maximum capacity (50 ml: 2.6 +/- 0.4 cm, max. cap. 2.5 +/- 0.4 cm; P = 0.003) and it descended further with the Valsalva maneuver (50 ml: 1.9 +/- 1.2 cm, max. cap. 1.7 +/- 1 cm; P = 0.004). There was also a higher degree of urethral rotation (50 ml: 41 +/- 30 degrees, max. cap. 39 +/- 20 degrees) with an empty bladder (P = 0.072). As regards funneling of the bladder neck on Valsalva, equivalent results were obtained for 90 patients. In 19 cases there were discrepancies (Cohen's kappa 0.64). For extensive funneling to the midurethra the respective numbers were 83 and 26 (kappa 0.41). Generally simple and extensive funneling was more frequently seen with a full rather than an empty bladder, simple funneling being diagnosed in an additional 14 cases (P = 0.06) and extensive funneling in an additional 19 (P = 0.03). It was concluded that bladder filling influences the position and mobility of the bladder neck and the proximal urethra, which are both more mobile when the bladder is nearly empty. Funneling of the proximal urethra, however, is more easily observed with a full bladder. Imaging of the lower urinary tract should be undertaken at defined bladder volumes.

Female↗
PubMed1999

Modelling in nutrition: an introduction.

The purpose of the present paper is to provide an introduction to modelling, particularly mathematical modelling, for nutritional researchers with little or no experience of the modelling process. It aims to outline the function of modelling, and to give some guidance on factors to consider when designing protocols to generate data as part of the modelling process. It is not intended in any way to be a comprehensive guide to mathematical modelling. The paper discusses the uses of modelling, and presents a 'hydrodynamic analogy' to compartmental modelling, to explain the process to the non-mathematically-minded and to examine some of the pitfalls to be avoided when using stable-isotope tracers. Examples of the use of modelling in nutrition are presented, including methods for determining absorption, as well as a discussion of possible future avenues for nutritional modelling.

Absorption↗