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Biomedical subjects

J Chapman

Publications and source records attributed to J Chapman.

At least 217 records · Page 12Linked to original sources
PubMed1996

Expression of a recombinant kringle V of human apolipoprotein(a): antibody characterization and species specificity.

Lipoprotein(a) is a macromolecular complex consisting of a low-density lipoprotein-like particle with an additional glycoprotein, apolipoprotein(a) [apo(a)], linked to apolipoprotein B-100 via a disulfide bond. Apo(a) is highly homologous to plasminogen. We have cloned the sequence corresponding to the kringle V domain of apo(a) from human liver cDNA using an experimental approach involving use of the polymerase chain reaction. The protein product of this clone was expressed in the cytoplasmic compartment of Escherichia coli as a MalE fusion protein. Fusion apo(a) Kr V was isolated from cytoplasmic extracts and purified by amylose-agarose affinity chromatography by eluting with 10 mM maltose. The fusion protein was injected into sheep in order to generate a polyclonal anti-apo(a) Kr V antibody. The antibody raised reacted against both reduced Lp(a) and the C-terminal domain of apo(a), corresponding to a sequence extending from Kr 33 to the C-terminal residue, but did not react with the N-terminal domain containing the repeated Kr IV sequences. The presence of the Kr V sequence was detected in every human apo(a) size isoform tested but only in apo(a) from human and chimpanzee among a panel of apo(a) proteins derived from different animal species.

ATP-Binding Cassette Transporters↗
PubMed1996

The validation of a 7-locus multiplex STR test for use in forensic casework. (I). Mixtures, ageing, degradation and species studies.

We have evaluated a multiplex STR system for routine forensic use, which co-amplifies six short tandem repeat (STR) loci; HUMTH01, D21S11, D18S51, D8S1179, HUMVWF31/A and HUMFIBRA (FGA), in conjunction with the X-Y homologous gene Amelogenin. Analysis of PCR products employs denaturing polyacrylamide gels coupled with fluorescent labelled primers and detection is undertaken on ABD 373A automated sequencers. The technique was shown to be robust and reproducible when samples were analysed under conditions consistent with those encountered in a forensic environment. The system was demonstrated to be human specific and is suitable for use with both aged and degraded material. Somatic stability was proven with a wide range of tissue types and we were able to detect mixtures at ratios between 1:10 and 10:1. During this study no incidence of sample mis-typing due to allelic or locus drop-out was observed. Furthermore, although additional artefact bands were occasionally encountered these did not interfere with the interpretation of results. The performance of the system with poor quality samples demonstrated its suitability as a powerful tool in forensic investigation.

Adult↗
PubMed1996

A novel mutation of presenilin 1 in familial Alzheimer's disease in Israel detected by denaturing gradient gel electrophoresis.

Germline mutations in the presenilin 1 (PS1) gene apparently account for the majority of early-onset, familial Alzheimer's disease (AD). Using a mutation-screening strategy (denaturing gradient gel electrophoresis; DGGE), we analyzed a large family with early onset AD and seizures. The patients in this family showed a novel missense mutation in exon 5 of the PS1 gene (A to T change in codon 120, altering glutamine to aspartic acid). This novel mutation is located within the second hydrophilic domain of the molecule, a region not particularly involved in previously described germline mutations, and is of unknown biological significance. These results also demonstrate that DGGE can be used effectively to screen for mutations within this gene.

Alzheimer Disease↗
PubMed1996

Congenital entropion and congenital corneal ulcer.

PURPOSE: We studied a case of corneal ulceration in utero from lower eyelid entropion. METHODS: A 3-week-old male infant was referred for examination of a left corneal ulcer that was present at birth and unresponsive to antibiotics. RESULTS: Examination disclosed a lower eyelid entropion that was treated surgically by a nonincisional method, leaving a central leukoma after re-epithelialization. CONCLUSION: Congenital lower eyelid entropion should be included in the differential diagnosis of congenital corneal opacities.

Corneal Opacity↗
PubMed1996

Transfusion-related acute lung injury due to HLA-A2-specific antibodies in recipient and NB1-specific antibodies in donor blood.

Transfusion-related acute lung injury (TRALI) is a hazardous but little-known complication of blood transfusion, characterized by non-cardiogenic lung oedema after blood transfusion. Leucoagglutinating antibodies in the donor plasma are considered to play a central role in the pathogenesis of TRALI but no recommended procedure currently exists for their detection, and most of them have not yet been well characterized. Serum samples of two patients who have developed TRALI within 30 min of blood transfusion and the sera of the involved blood donors were investigated for leucocyte antibodies by granulocyte immunofluorescence, granulocyte agglutination and lymphocytotoxicity assays using typed test cells. Suspected specificities of the detected antibodies were confirmed by a luminoimmunoblot assay and the antigen capture assay MAIGA. One case was associated with granulocyte agglutinating anti-HLA-A2 antibodies in the recipient's (i.e. patient's) own blood and the other with donor-related non-agglutinating antibodies directed against the granulocyte-specific antigen NB1. Leucocyte incompatibility between donor and recipient was shown in both cases by crossmatching and typing of the incompatible cells for the appropriate antigen. The results show that TRALI is associated not only with donor- but also with recipient-related leucocyte antibodies. In addition to leucoagglutinating antibodies, non-agglutinating granulocyte-specific antibodies can be also involved. For immunodiagnosis, sera from both must be investigated by a combination of granulocyte and lymphocyte (HLA) antibody screening tests and leucocyte incompatibility verified by crossmatching.

GPI-Linked Proteins↗
PubMed1996

APOE-epsilon 4 in patients with Alzheimer disease and vascular dementia.

The apolipoprotein E (APOE) epsilon 4 allele has been consistently found to be frequent in patients with progressive degenerative dementia of the Alzheimer type (DAT). Vascular dementia (VD) may occur as strokes superimposed on presymptomatic DAT, in which case APOE-epsilon 4 frequency should also be increased in VD. We have examined the distribution of APOE-epsilon 4 in patients with DAT (n = 176) or VD (n = 74) and controls (n = 133), and evaluated the risk of dementia associated with APOE-epsilon 4. APOE-epsilon 4 allele frequency was 27% in DAT patients, 21% in VD patients, and 11% in controls. The difference in the distribution of the epsilon 4 allele between DAT or VD patients and controls was statistically significant (chi(2) test, p < 0.05), with a 3.6- and 2.1-fold risk of dementia in DAT and VD patients carrying an epsilon 4 allele. The result that the APOE-epsilon 4 allele is more frequent in DAT patients than in controls, with VD patients falling in between, is consistent with the assumption that VD is a heterogeneous condition, with some patients having an underlying preclinical brain degeneration, in whom the dementia was precipitated by strokes.

Aged↗
PubMed1996

Relationship of mechanical factors to the strength of proximal femur fractures fixed with cancellous screws.

The decision of whether to attempt screw fixation of a femoral neck fracture is based partly on the estimated strength of the fixed bone/implant construct in relation to the loads it will be required to bear. The goal of this study was to determine in vitro the relation of the following biomechanical factors to the strength of internally fixed femoral neck fractures subjected to cyclic and failure loading: (a) square of the density of cancellous bone in the femoral head, (b) percent comminution of the inferior fracture surface, (c) moment arm of the joint force, or distance from the axis of the joint force to the fracture surface, and (d) orientation angle of the fracture surface in the medial/lateral plane relative to the axis of the femoral shaft. Femoral neck fractures were created in each of 38 fresh cadaveric proximal femora using a dropweight or with a materials testing machine. After sustaining a displaced fracture, fixation was achieved using three cannulated cancellous bone screws. The fixed femur was then subjected to 10,000 cycles of a sinusoidially varying load acting on the femoral head, parallel to the femoral shaft, with an initial peak magnitude of 2.2 times body weight, while the hip was flexed, extended, and rotated to mimic some motions of gait. Muscle loading was not simulated. The magnitude of the peak load decreased as the femoral head displaced during cycling. The mean of the peak load for each cycle over the duration of the test was defined as the average load. Following cycling, the bone/screw construct was loaded to failure in the same direction, and this measurement was termed the maximum load. Average and maximum load were then correlated to the four biomechanical factors using a multiple regression analysis. These factors correlated to a high degree with average force (R2 = 0.771; p < 0.0001) and to a lesser but still significant degree with maximum force (R2 = 0.458; p = 0.012), demonstrating that they can be used to estimate the strength of fixation under these loading conditions. The strongest correlation for average force was with fracture angle (p = 0.005) and for failure force was with moment arm length (p = 0.072).

Biomechanical Phenomena↗
PubMed1996

Fatal insomnia in a case of familial Creutzfeldt-Jakob disease with the codon 200(Lys) mutation.

Fatal familial insomnia (FFI) has been exclusively associated with a pathogenic mutation at codon 178 in the PRNP gene coupled with methionine (Met) at codon 129. We now describe a subject with familial Creutzfeldt-Jakob disease, heterozygous for the pathogenic lysine (Lys) mutation at codon 200 and homozygous for Met at codon 129 of the PRNP gene, who was affected by severe insomnia. At autopsy the patient had significant involvement of the thalamus, as previously described in subjects affected by FFI with the codon 178 mutation. This case demonstrates the wide variability of the clinical expressions in patients with the codon 200 mutation, that may include insomnia and thalamic pathology.

Amyloid↗
PubMed1996

Pruritus in Creutzfeldt-Jakob disease.

We report three patients with Creutzfeldt-Jakob disease, whose first symptom was severe pruritus, similar to that observed in scrapie. The pruritus was resistant to therapy. The underlying mechanisms are unclear, but we speculate that the pruritus may result from brainstem involvement.

Creutzfeldt-Jakob Syndrome↗
PubMed1996

Delisting of drugs in Ontario. How attitudes and prescribing strategies of family physicians in the Kingston area changed.

OBJECTIVE: To assess how attitudes and prescribing strategies of family physicians changed when drugs were delisted from the Ontario Drug Benefit formulary. DESIGN: Mailed, self-administered survey. SETTING: Family physicians' offices in Ontario. PARTICIPANTS: All family physicians practising in the Kingston, Frontenac, Lennox, and Addington Health District. MAIN OUTCOME MEASURES: Physicians were presented with six vignettes involving patients receiving a delisted drug. The choices were to recommend the patient pay for the medication, to substitute a drug still listed on the formulary, to make a special request that the medication be covered for this patient, or to offer another option. As well, the physicians were asked to indicate, on a 5-point Likert scale, their opinions regarding the effect of delisting on themselves and their patients. RESULTS: Physicians were most likely to change to a medication that was still on the formulary. Patient sex and ability to pay were factors in physicians' decisions. Physicians believe that the delistings are not likely to have adversely affected patients' health, that noncompliance is a problem because many once-daily formulations have been removed, that suitable alternatives are not always available, and that physicians should have been consulted more before the changes were made. CONCLUSIONS: Physicians usually substitute listed medications for medications that have been delisted. This is especially true for female patients and patients who are unable to pay.

Adult↗
PubMed1996

[Towards gene therapy in familial hypercholesterolemia].

Familial hypercholesterolemia (FH) is an inherited disease caused by a defect in the gene encoding the Low Density Lipoprotein receptor (LDL-R). The ex vivo hepatic gene therapy which restore the expression of the normal protein in hepatocytes should correct the disease. Improved transduction efficiency and long lasting expression of the transduced gene remain the main goals of gene therapy research. We developed an efficient and reliable method for in vivo transduction of human, mouse and primate primary hepatocytes. A retroviral vector bearing the LDL-R cDNA driven by the liver-type pyruvate kinase promoter allows high and tissue specific expression of the gene in primary hepatocytes. A second vector with a housekeeping promoter corrects the LDL-R deficiency in fibroblasts from a FH patient. Ex vivo preclinical studies in non-human primates will provide new insight in transduced cells biology after reimplantation.

Animals↗
PubMed1996

beta-Carotene treatment of cervical intraepithelial neoplasia: a phase II study.

The use of Papanicolaou smears for cervical cancer screening has led to an increased detection of preinvasive conditions of the cervix, cervical intraepithelial neoplasia (CIN). Epidemiological studies have shown an association between low levels of dietary beta-carotene and CIN. In this Phase II study, we have explored the effect of p.o. beta-carotene administration on CIN I and II. Patients with documented CIN I or II were treated with 30 mg daily of beta-carotene for 6 months. Response rates were determined at 0, 3, 6, and 12 months with cytology, colposcopy, and/or biopsies. Levels of beta-carotene and vitamin E were determined at the same time intervals in vaginal mucosa cells and serum. Response rates were 18 of 30 (60%), 21 of 30 (70%), and 10 of 30 (33%) at 3, 6, and 12 months, respectively. Significant changes occurred in the serum beta-carotene levels over time. Median levels over 2200 mg/ml were found at 3 and 6 months versus a baseline median level of 111 (P < 0.0001). Significant increases were also noted in the beta-carotene levels of the vaginal mucosa compared to baseline (P = 0.01) and a significant correlation was noted between serum and vaginal beta-carotene levels as well (P < 0.0001). This study indicates that a large percentage of patients with CIN I and II will respond clinically to p.o. beta-carotene supplementation. There is a positive relationship between serum and tissue levels of beta-carotene which suggests that serum levels can be used for monitoring purposes. Because of these encouraging results, prospective randomized studies are ongoing comparing the efficacy of beta-carotene against an untreated control arm.

Antioxidants↗
PubMed1995

Characterization of the N-terminal and C-terminal domains of human apolipoprotein(a): relevance to fibrin binding.

The structural domains of human apolipoprotein(a) (apo(a)) in the lipoprotein(a) (Lp(a)) particle have been recently investigated by limited proteolysis [Huby, T., Doucet, C., Dieplinger, H., Chapman, J., & Thillet, J. (1994) Biochemistry 33, 3335-3341]. We have shown that apo(a) can be cleaved into two structural domains: one was of constant size (170 kDa) and corresponded to the C-terminal (Cter) domain of apo(a). This domain was linked by a disulfide bond to apo B100. By contrast, the N-terminal (Nter) domain, whose size varied according to the digested apo(a) isoform, was not linked to apo B100. We now describe the purification of these apo(a) domains and their interaction with fibrin surfaces in an in vitro binding assay. The Nter domain of apo(a) was purified as a soluble protein in a two-step procedure which involved sequential use of a heparin-Sepharose column and a lysine-Sepharose column. The Cter domain of apo(a), which remained in disulfide linkage with apo B100 of Lp(a), was isolated as a lipoprotein particle by a combination of chromatographic steps on heparin-Sepharose and Q-Sepharose columns. This particle, termed "mini-Lp(a)", appeared homogeneous in nondenaturing polyacrylamide gels and exhibited a particle size (285 A) which was intermediate between that of Lp(a) (300 A) and LDL (265 A). The cleavage site between the respective apo(a) domains was determined by N-terminal sequencing of the purified Cter domain. Such cleavage occurred between residues 3532 and 3533, which are located in the interkringle region between apo(a) kringles 4(4) and 4(5).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗