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J MacKenzie

Publications and source records attributed to J MacKenzie.

At least 19 recordsLinked to original sources
PubMed2003

Predictive, pre-natal and diagnostic genetic testing for Huntington's disease: the experience in Canada from 1987 to 2000.

Predictive and pre-natal testing for Huntington's Disease (HD) has been available since 1987. Initially this was offered by linkage analysis, which was surpassed by the advent of the direct mutation test for HD in 1993. Direct mutation analysis provided an accurate test that not only enhanced predictive and pre-natal testing, but also permitted the diagnostic testing of symptomatic individuals. The objective of this study was to investigate the uptake, utilization, and outcome of predictive, pre-natal and diagnostic testing in Canada from 1987 to April 1, 2000. A retrospective design was used; all Canadian medical genetics centres and their affiliated laboratories offering genetic testing for HD were invited to participate. A total of 15 of 22 centres (68.2%), currently offering or ever having offered genetic testing for HD, responded, providing data on test results, demographics, and clinical history. A total of 1061 predictive tests, 15 pre-natal tests, and 626 diagnostic tests were performed. The uptake for predictive testing was approximately 18% of the estimated at-risk Canadian population, ranging from 12.5% in the Maritimes to 20.7% in British Columbia. There appears to have been a decline in the rate of testing in recent years. Of the predictive tests, 45.0% of individuals were found to have an increased risk, and a preponderance of females (60.2%) sought testing. A greater proportion of those at < or = 25% risk sought predictive testing once direct CAG mutation analysis had become available (10.9% after mutation analysis vs 4.7% before mutation analysis, p = 0.0077). Very few pre-natal tests were requested. Of the 15 pre-natal tests, 12 had an increased risk, resulting in termination of pregnancy in all but one. Diagnostic testing identified 68.5% of individuals to be positive by mutation analysis, while 31.5% of those with HD-like symptoms were not found to have the HD mutation. The positive diagnostic tests included 24.5% of individuals with no known prior family history of HD.

Adolescent↗
PubMed2001

IL-13 induces airways hyperreactivity independently of the IL-4R alpha chain in the allergic lung.

The potent spasmogenic properties of IL-13 have identified this molecule as a potential regulator of airways hyperreactivity (AHR) in asthma. Although IL-13 is thought to primarily signal through the IL-13Ralpha1-IL-4Ralpha complex, the cellular and molecular components employed by this cytokine to induce AHR in the allergic lung have not been identified. By transferring OVA-specific CD4(+) T cells that were wild type (IL-13(+/+) T cells) or deficient in IL-13 (IL-13(-/-) T cells) to nonsensitized mice that were then challenged with OVA aerosol, we show that T cell-derived IL-13 plays a key role in regulating AHR, mucus hypersecretion, eotaxin production, and eosinophilia in the allergic lung. Moreover, IL-13(+/+) T cells induce these features (except mucus production) of allergic disease independently of the IL-4Ralpha chain. By contrast, IL-13(+/+) T cells did not induce disease in STAT6-deficient mice. This shows that IL-13 employs a novel component of the IL-13 receptor signaling system that involves STAT6, independently of the IL-4Ralpha chain, to modulate pathogenesis. We show that this novel pathway for IL-13 signaling is dependent on T cell activation in the lung and is critically linked to downstream effector pathways regulated by eotaxin and STAT6.

Adoptive Transfer↗
PubMed2001

Screening for herpesvirus genomes in common acute lymphoblastic leukemia.

There is epidemiological evidence that infection may play a role in the etiology of childhood leukemia in particular common B cell precursor acute lymphoblastic leukemia. A panel of 20 leukemic samples (panel 1) was examined for the presence of four lymphotropic herpesviruses using conventional molecular techniques. A second independent panel of 27 leukemic samples (panel 2), along with 28 control peripheral blood samples from children with other forms of cancer, was tested for the presence of the same four viruses using sensitive real-time quantitative PCR. While herpesvirus genomes were detected, they were present at very low levels; detection rates and levels were similar in the leukemic and control panels. In addition we surveyed 18 leukemic samples (five from panel 1, six from panel 2 and a further seven samples not previously analyzed) using a degenerate PCR assay capable of detecting the genomes of known herpesviruses plus putative new members of the family. No novel herpesvirus genomes were detected suggesting that a herpesvirus is unlikely to be etiologically involved as a transforming agent in common acute lymphoblastic leukemia.

Adolescent↗
PubMed1999

Detection of Epstein-Barr virus (EBV) genomes in the serum of patients with EBV-associated Hodgkin's disease.

DNA from malignant cells is present in the serum/plasma of cancer patients and DNA from this source is amenable to analysis by polymerase chain reaction (PCR). In the present study, we evaluated whether Epstein-Barr virus (EBV) DNA is present in the serum of patients with EBV-associated Hodgkin's disease (HD). Using conventional PCR, EBV DNA was detected in serum from 30/33 patients with EBV-associated HD but in only 6/26 patients with non-EBV-associated disease (p < 0.001). Samples from healthy individuals were negative and only 5/12 infectious mononucleosis samples were positive. Real-time quantitative PCR was subsequently employed to determine the concentration of EBV DNA present in serum; among positive samples the level ranged from 1 to 705 copies per 125 microliter of serum. Post-treatment samples from 5/14 cases with EBV-associated HD contained detectable EBV DNA; analysis of this small group of cases suggests that positivity in post-treatment samples correlates with risk factors indicative of a poor prognosis. Overall, our results are consistent with the notion that DNA from Reed-Sternberg cells is present in the serum of HD patients, and further suggest that serum EBV should be evaluated as a prognostic marker. Int. J. Cancer (Pred. Oncol.) 84:442-448, 1999.

Adult↗
PubMed1999

JC and BK virus sequences are not detectable in leukaemic samples from children with common acute lymphoblastic leukaemia.

Epidemiological evidence suggests that childhood leukaemia, and possibly common acute lymphoblastic leukaemia in particular, may have an infectious aetiology. Smith (1997 J Immunother 20: 89-100) recently suggested that the critical infectious event occurs during pregnancy, and identified the polyoma virus JC as a candidate agent. In the present study we investigated whether genomes from the JC virus, and closely related BK virus, could be detected in leukaemic cells. No positive results were obtained suggesting that JC virus is unlikely to play a direct role in leukaemogenesis.

BK Virus↗
PubMed1999

Epstein-Barr virus and other candidate viruses in the pathogenesis of Hodgkin's disease.

The epidemiologic and clinicopathologic features of Hodgkin's disease (HD) suggest that an infectious agent is involved in the etiology. Over the last 12 years, evidence has accumulated suggesting that Epstein-Barr virus (EBV) is associated with a proportion of cases: EBV genomes are present in Reed-Sternberg (HRS) cells and viral proteins including LMP1, which has oncogenic potential, are expressed. HD has a complex epidemiology and EBV-associated cases are not randomly distributed. Disease occurring in early childhood and older adult age groups is more likely to be EBV-associated than for young adult cases. Paradoxically, there is more evidence supporting an infectious etiology in the latter group of younger patients. Defective EBV genomes and "hit and run" mechanisms involving EBV cannot account for all cases, and the direct involvement of known viral agents, including other lymphotropic herpesviruses, has largely been excluded. Hitherto unknown virus may be responsible for the peak incidence in young adults, which is a feature of HD in developed countries.

Adolescent↗
PubMed1998

Local research ethics committee approval for a national study in Scotland.

The handling of research proposals by different ethics committees has been reported as varying widely from one district to another. Multicentre research projects are particularly liable to delay when dealing with several individual committees. We recently performed a nation-wide postal questionnaire study in Scotland on young patients with oral or oropharyngeal cancer. Our experience indicates that despite calls for standardization of the processes involved wide variations still exist between committees. Fifteen out of 19 committees approached had unique application forms, the number of copies of forms and other documentation required ranged from one to 20, and the time to final approval ranged from 39 to 182 days (mean of 90 days). Improved training and a standardized constitution of committee members is required. A uniform national application form and improved co-operation between neighbouring committees is needed.

Ethics Committees↗
PubMed1997

Discharge planning. Oiling the wheels.

A liaison nurse can ensure effective discharge planning, enhance the services provided and introduce quality improvements. Employing a liaison nurse in a children's private patient directorate has reduced the length of patient stay, and stopped wards being used for outpatient sessions for children receiving follow-up treatment. Ward nurses have more time to spend with inpatients, so that children and their families benefit from a more comprehensive service and continuity of care is improved.

Ambulatory Care↗
PubMed1997

Determination of HLA-A*02 antigen status in Hodgkin's disease and analysis of an HLA-A*02-restricted epitope of the Epstein-Barr virus LMP-2 protein.

There is good evidence for an association between Epstein-Barr virus (EBV) and Hodgkin's disease (HD). In approximately one-third of cases, the EBV genome is detectable in Reed-Sternberg (RS) cells and there is expression of the viral nuclear antigen EBNA-1 and the latent membrane protein LMP-1. Expression of LMP-2 has been demonstrated at the mRNA level, and it is presumed that the protein is expressed alongside LMP-1. The LMP-2 protein is known to contain an epitope presented to cytotoxic T-cells which is restricted through the HLA class I antigen A*0201 in healthy seropositive individuals. Since most HLA-A*02-positive Caucasians are HLA-A*0201-positive, it was hypothesized that HLA-A*02-positive individuals would be under-represented among Caucasians with EBV-associated HD. HLA-A*02 status was determined, using flow cytometry and/or the polymerase chain reaction, for 276 individuals including 176 cases of HD. There was no significant difference between the frequency of HLA-A*02 positivity in HD cases and controls, and between EBV-associated and non-associated cases of HD. The A*02 alleles of 14 cases of EBV-associated HD were further subtyped using nested PCR; all except one case were found to be A*0201-positive. We therefore investigated whether there was any evidence for mutation of the epitope representing amino acids 426-434 of LMP-2a which is restricted through HLA-A*0201. In 10/11 cases the nucleotide sequence encoding this epitope was identical to the published sequence; in the remaining case there was a mutation which would not be expected to alter the conformation of the epitope. Overall, our data suggest that other mechanisms of immune escape must be operative in EBV-associated HD.

Adolescent↗
PubMed1997

Formal retrospective case review and sudden infant death.

A review of 24 consecutive sudden infant deaths was undertaken to evaluate the importance of the various stages in the postmortem assessment of such cases. Death in three cases was caused by obvious trauma. Of the remainder, 16 were attributed to sudden infant death syndrome (SIDS), 4 to accidental asphyxia (identified by death scene examination and/or formal case review) and 1 to a lingual thyroglossal duct cyst. Three (14%) of 21 deaths thought to be SIDS after postmortem examination were attributed to asphyxia following subsequent formal case review.

Autopsy↗
PubMed1995

Paravertebral blockade. Failure rate and complications.

The failure rate and complications were studied prospectively in 367 paediatric and adult patients who had received a thoracic or lumbar paravertebral block. The overall failure rate was 10.1%; adults 10.7%; children 6.2%. The frequency of complications were: hypotension: 4.6%; vascular puncture: 3.8%; pleural puncture: 1.1%; pneumothorax: 0.5%. Since these results are similar to those found with alternative methods, e.g. epidural, intrapleural and intercostal blocks, paravertebral block can be recommended as an effective, safe technique for unilateral analgesia in both adults and children.

Adolescent↗
PubMed1995

Maternal distress and perceptions of infant development following extracorporeal membrane oxygenation and conventional ventilation for persistent pulmonary hypertension.

Neurodevelopmental outcome and concurrent maternal distress were examined for infants who suffered persistent pulmonary hypertension at birth and were treated with either extracorporeal membrane oxygenation (ECMO) (n = 19) or conventional ventilation (CV) (n = 15). Mothers were asked to complete inventories assessing their infant's (mean age 8.74 months) developmental growth as well as their own psychological health. Relevant sociodemographic and treatment parameters were also entered into the analysis. The results indicated that ECMO and CV infants did not differ on developmental indices and impairment rates were 15-23% respectively, similar to previous reports. In addition, ECMO and CV mothers did not differ in their reports of psychological distress. Correlational analyses revealed that length of treatment for ECMO but not CV infants significantly predicted developmental delay and maternal distress. For CV mothers, maternal distress was associated with the perception of delayed language. The results are discussed in terms of the limited morbidity associated with ECMO and CV interventions and the possible role of a 'vulnerable child syndrome' in understanding the maternal-infant relationship following ECMO therapy.

Child Development↗
PubMed1995

Need for overnight respite for primary caregivers of hospice clients.

A major reason for admission of community hospice clients to the hospital is exhaustion of the primary caregiver. One way to prevent the problem of caregiver exhaustion may be the use of trained laypersons who remain overnight with the ill person, thereby providing respite that allows the caregiver to sleep. A survey was conducted to assess primary caregivers' appraisal of the need for overnight respite and their willingness to receive this support from trained laypersons. Thirty-seven primary caregivers, who used the services of a community hospice, were interviewed to determine primary caregivers' appraisals of problems, resources, and needs. Ten (27%) primary caregivers reported usually receiving 0 to 4 of sleep per night and 27 (73%) reported receiving > 4 h. Sleep time was described by the majority as insufficient, but insufficient, sleep was statistically not a main reason for hospital admission. Findings suggested that those in the 0- to 4-h category were more vulnerable to exhaustion. Seventy percent of respondents indicated that they would use the services of a trained layperson for overnight respite and an additional 6% indicated that they would under certain conditions.

Aged↗
PubMed1994

Aggregation of the chemokine MIP-1 alpha is a dynamic and reversible phenomenon. Biochemical and biological analyses.

Macrophage inhibitory protein (MIP)-1 alpha is a potent inhibitor of hemopoietic stem cell proliferation and is a member of a family of pro-inflammatory mediators, the chemokine family. This molecule along with other members of the chemokine family exists as a peptide of 8 kDa but has a strong tendency for noncovalent extensive self-aggregation. As this aggregation may interfere with biological activity, we have produced nonaggregating variants of MIP-1 alpha which display a range of molecular sizes. The mutants, produced by sequential neutralization of carboxyl-terminal acidic residues, display native molecular masses representative of tetramers, dimers, and monomers. Intriguingly when these mutants are assessed in comparison with native MIP-1 alpha for bioactivity in vitro, they are seen to be equipotent in both stem cell assays and in monocyte shape-change assays, suggesting that there is no requirement for aggregation in either of these biological contexts. This indicates that the aggregated MIP-1 alpha and the aggregated mutants spontaneously disaggregate under assay conditions and ultimately function as monomers. We have further demonstrated the ability of MIP-1 alpha to disaggregate spontaneously in dilute solution by enzyme-linked immunosorbent assay analysis of fractions obtained from gel filtration of varying concentrations of MIP-1 alpha. The aggregation of MIP-1 alpha is therefore a dynamic and reversible phenomenon which has little, if any, impact on bioactivity in vitro.

Amino Acid Sequence↗
PubMed1994

Penoscrotal transposition: a case report and review.

We report on a boy born with complete penoscrotal transposition, normal scrotum, twisted penile shaft with hypoplastic penile urethra, meatal stenosis, normal bladder, and bilateral cystic dysplastic kidneys. The patient died of renal failure at 2.5 months. This is the 13th reported case of complete penoscrotal transposition with normal scrotum. The possible pathogenesis is discussed and the literature is reviewed.

Abnormalities, Multiple↗
PubMed1994

Hyperthyroidism secondary to a pituitary adenoma secreting TSH, FSH, alpha-subunit and GH.

A 51-year-old man had been treated for hyperthyroidism with antithyroid drugs for 8 years. He was then found to have a large pituitary adenoma with biochemical evidence of overproduction of TSH, FSH and alpha-subunit. Subsequent immunocytochemical and tissue culture studies confirmed secretion of these hormones. In addition, the tumour stained for GH and was capable of GH production in vitro. This combination of hormones produced by a pituitary adenoma has not been previously reported.

Adenoma↗