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Biomedical subjects

J M MacKenzie

Publications and source records attributed to J M MacKenzie.

16 recordsLinked to original sources
PubMed1999

Application of a DNA hybridization-hydrophobic-grid membrane filter method for detection and isolation of verotoxigenic escherichia coli.

Verotoxigenic Escherichia coli (VTEC) strains were isolated from food and animal fecal samples by using PCR to screen for the presence of VTEC after broth enrichment and then filtering VTEC-positive cultures through hydrophobic-grid membrane filters (HGMFs) which were incubated on MacConkey agar. The filters were probed with a digoxigenin-labeled PCR product generated by amplification of a conserved verotoxin gene sequence. Replication of the growth on filters allowed probe-positive colonies to be picked. When ground beef samples were inoculated with VTEC strains, 100% of the strains were recovered, and the detection limit was 0.1 CFU per g. Similar results were obtained with seven types of artificially contaminated vegetables. A survey of 32 packages of vegetables and 23 samples of apple cider obtained at the retail level did not reveal the presence of VTEC. However, the intestinal fecal contents of a moose, 1 of 35 wild mammals and birds examined, contained E. coli O157:H7. The DNA hybridization-HGMF method was also used in a prevalence survey of 327 raw and 744 ready-to-eat products; VTEC strains were recovered from 4.9% of the raw products and 0.7% of the ready-to-eat products. No serotype O157:H7 strains were detected. This method is particularly suited for surveys in which low numbers of VTEC-positive samples are expected and isolates are required.

Animals↗
PubMed1996

Malignant meningitis: a rational approach to cerebrospinal fluid cytology.

AIM: To clarify laboratory guidelines for cerebrospinal fluid (CSF) cytology. METHODS: Clinical and pathological data relating to 54 patients with cytologically malignant cells in the CSF were reviewed, together with CSF cell counts and protein measurements for 29 patients. Utilising this data, criteria were established for CSF cytology and validated by review of 100 patients in whom CSF cytology had not been carried out on the basis of these criteria. RESULTS: There was only one false positive diagnosis of malignancy on the basis of CSF cytology. All patients with malignant cells in the CSF fulfilled at least one of the following criteria: clinically known or suspected malignancy; raised cell count; raised protein concentration. In none of the 100 patients, in whom cytology was not performed, was the diagnosis of malignant meningitis missed. CONCLUSION: Cytology should be performed on CSF specimens from all patients with known, or suspected, malignancy, but in other cases, only if the cell count or protein concentration, or both, is raised.

Adenocarcinoma↗
PubMed1993

Opsoclonus-myoclonus syndrome: an autopsy study of three cases.

Opsoclonus-myoclonus is a rare clinical syndrome. We report three patients who died with a pure opsoclonus-myoclonus syndrome. The presentation, management and associations of this distinctive condition are discussed, and the results of detailed pathological examination described. In each case the only abnormality was perivascular collections of lymphocytes widely distributed in the brain. This supports an immune-mediated rather than structural aetiology.

Aged↗
PubMed1992

Prolactin secreting pituitary carcinoma.

A man with a prolactin secreting pituitary carcinoma was treated by surgery and radiotherapy. Persistent hyperprolactinaemia partially responded to oral bromocriptine for four years. Serum prolactin then rose considerably with rapid, invasive tumour recurrence. Cytotoxic chemotherapy halted tumour progression for twelve months before fatal spread throughout the brain. Failure to normalise serum prolactin with bromocriptine may precede an aggressive course in patients with prolactinoma.

Adult↗
PubMed1991

X-linked and FSH dystrophies in one family.

A family is reported in which the father was affected by facioscapulohumeral muscular dystrophy FSHD. One son was affected by Duchenne muscular dystrophy (DMD). The second son died at the age of 3 yr of a severe primary muscle disease and it is suggested that this was the outcome of dual expression of the two conditions.

Adult↗
PubMed1989

Antibodies to nystatin demonstrate polyene sterol specificity and allow immunolabeling of sterols in Saccharomyces cerevisiae.

Polyclonal antibodies elicited by injection into rabbits of a nystatin-bovine serum albumin conjugate were reactive with both nystatin and amphotericin B. Upon labeling of polyene-treated Saccharomyces cerevisiae sterol auxotrophs grown on various sterols, nystatin reacted specifically with ergosterol, while amphotericin B did not react preferentially with ergosterol, cholesterol, or cholestanol. Time course labeling experiments demonstrated the rate of ergosterol transport into cholesterol-grown cells.

Animals↗
PubMed1987

An immunohistochemical study of the enteric neural plexi in Hirschsprung's disease.

The diagnosis of Hirschsprung's disease relies upon histology and acetylcholinesterase histochemistry of the enteric neural plexi. A distinctive neurofilament protein staining pattern has been claimed in Hirschsprung's disease. We studied 10 colons affected by Hirschsprung's disease, together with appropriate controls using antibodies to neurofilament protein (NFP; monoclonal), neurone-specific enolase (NSE), glial fibrillary acidic protein (GFAP) and S-100 protein (all polyclonal), and conventional histology and histochemistry, seeking an immunohistochemical diagnostic method. We found staining for NFP, NSE and S-100 protein of many of the nerve fibres and satellite cells in the enteric plexi, but without significant differences between affected and unaffected colons. Staining for GFAP was weakly positive in a minority of cases and controls and the majority of neurones in control sections stained for NSE. In contrast to acetylcholinesterase little staining was localized in the lamina propria. Staining for NSE and S-100 is useful in identifying immature ganglion cells in paediatric large intestine.

Acetylcholinesterase↗
PubMed1971

Mode of host cell penetration by bacteriophage phi X174.

Bacteriophage phiX174 is an icosahedral phage which attaches to host cells without the aid of a complex tail assembly. When phiX174 was mixed with cell walls isolated from the bacterial host, the virions attached to the wall fragments and the phage deoxyribonucleic acid (DNA) was released. Attachment was prevented if the cell walls were treated with chloroform. Release of phage DNA, but not viral attachment, was prevented if the cell walls were incubated with lysozyme or if the virions were inactivated with formaldehyde. Treatment of the cell walls with lysozyme released structures which were of uniform size (6.5 by 25 nm). These structures attached phiX174 at the tip of one of its 12 vertices, but the viral DNA was not released. The virions attached to these structures were oriented with their fivefold axis of symmetry normal to the long axis of the structure. No virions were attached to these structures by more than one vertex. Freeze-etch preparations of phiX174 adsorbed to intact bacteria showed that the virions were submerged to one half their diameter into the host cell wall, and the fivefold axis of symmetry was normal to the cell surface. A second cell could not be attached to the outwardly facing vertex of the adsorbed phage and thus the phage could not cross-link two cells. When the virions were labeled with (3)H-leucine, purified, and adsorbed to Escherichia coli cells, about 15% of the radioactivity was recovered as low-molecular-weight material from spheroplasts formed by lysozyme-ethylenediaminetetraacetic acid. Other experiments revealed that about 7% of the total parental virus protein label could be recovered in newly formed progeny virus.

Binding Sites↗
PubMedDate not supplied

Pleomorphic xanthoastrocytoma in a 62-year-old male.

Pleomorphic xanthoastrocytoma has been described as a distinct clinicopathological entity with a relatively favourable prognosis. However, tumours closely resembling this entity have been shown to have the potential for aggressive behaviour, and to represent, on closer scrutiny, a number of disparate neoplasms. A case is described which, although otherwise typical of pleomorphic xanthoastrocytoma, occurred in a man of 62 years, and it is suggested that it should be considered a specific histological, rather than a clinicopathological entity.

Astrocytoma↗
PubMedDate not supplied

The evolution of an oligodendroglioma into a primitive neuroectodermal tumour.

Oligodendrogliomas may comprise a biologically heterogenous group of tumours. There is disagreement about the relationship between their histological features and subsequent behaviour, and evolution of histologically typical oligodendrogliomas into more malignant neoplasms has been described. We describe a supratentorial oligodendroglioma in a 4-year-old boy which recurred 9 months after initial resection when it showed foci of histologically primitive cells, not present in the initial specimen. It recurred again at the same site 20 months later following a course of radiotherapy, but showed on this occasion the appearances of a primitive neuroectodermal tumour (PNET) with astrocytic and ependymal, but not oligodendroglial, differentiation. The evidence suggests evolution of an oligodendroglioma into a PNET, and raises the possibility that some oligodendrogliomas may arise by differentiation from a pool of proliferating primitive cells which may occasionally become the dominant population.

Brain Neoplasms↗
PubMedDate not supplied

Are all cardio-embolic strokes embolic? An autopsy study of 100 consecutive acute ischaemic strokes.

Estimates of the frequency of different types of ischaemic stroke vary widely, particularly those said to be of embolic aetiology. This retrospective autopsy study of 100 acute ischaemic strokes was undertaken to clarify the incidence of cardio-embolic stroke. Criteria for separating cardio-embolic from other forms of stroke were defined. Using these criteria, 26% of acute ischaemic strokes were cardio-embolic, 28% thrombotic, 12% atheromatous and the remainder due to various other causes including hypoperfusion with 11% being of undetermined aetiology. A significantly higher incidence of non-hypertensive cardiac disease was found in the group in whom no thrombus or thrombo-embolus was found at autopsy, suggesting that some of these strokes may have been due to unrecognised cerebral hypoperfusion. Haemodynamic stroke is probably an important and underrecognised form of acute ischaemic stroke.

Acute Disease↗