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Biomedical subjects

J Liddell

Publications and source records attributed to J Liddell.

18 recordsLinked to original sources
PubMed2003

Isolated unilateral hypoglossal nerve paralysis caused by an atlanto-occipital joint synovial cyst.

An isolated unilateral hypoglossal nerve lesion is an uncommon cranial nerve palsy. We report a case of isolated hypoglossal nerve paralysis caused by an intra-dural synovial cyst. To our knowledge, this is the first reported case of a twelfth nerve paralysis caused by a synovial cyst. The anatomy of the hypoglossal nerve, its blood supply and the relationship of the nerve to the atlanto-occipital joint are reviewed, along with the common causes of isolated hypoglossal nerve paralysis.

Cranial Nerve Diseases↗
PubMed2002

Non-neoplastic demyelinating process mimicking a disseminated malignant brain tumour.

Non-neoplastic demyelinating processes of the brain with ring enhancing lesions and mass effect on MRI imaging, mimicking malignant brain tumours, are rare phenomena. We document the case of a 32 year old male with clinical, radiological and initial histological findings, suggestive of a malignant brain tumour. Additional investigations confirmed the diagnosis of multiple sclerosis. This case is significant as the lesion could not be easily distinguished from a malignant brain tumour on imaging alone. Cases such as this illustrate the importance of considering a demyelinating process in the differential diagnosis of tumour-like brain lesions.

Astrocytoma↗
PubMed2000

Percutaneous endoscopic laser discectomy.

BACKGROUND: The aim of the present paper was to systematically review the literature on percutaneous endoscopic laser discectomy (PELD) with respect to the safety and efficacy of the procedure. Where possible the procedure was compared with open discectomy. METHODS: Studies on PELD were identified using MEDLINE (1984 to December 1999), EMBASE (1974 to December 1999) and Current Contents (1993 to Week 1, 2000). A number of search terms were used: PELD; PLDD (percutaneous laser disc decompression); and laser and (spine or lumbar) and (disc* or disk*). The Cochrane Library was searched from 1966 to issue 4, 1999, using the search terms 'discectomy' or 'discotomy'. Live human studies of patients with lumbar disc prolapses for whom surgery was appropriate were included. Cadaver studies were also included. A surgeon and reviewer independently assessed the retrieved articles for their inclusion in the review. RESULTS: Only 12 papers were identified that related to PELD. The level of evidence for safety and efficacy was low; there were no controlled, blinded or randomized studies. The highest level of evidence came from time series studies. No quantitative analysis could be undertaken for the present review. CONCLUSIONS: Given the extremely low level of evidence available for this procedure it was recommended that the procedure be regarded as experimental until results are available from a controlled clinical trial, ideally with random allocation to an intervention and control group.

Cadaver↗
PubMed1998

Epithelial carcinogenesis in the mouse: correlating the genetics and the biology.

Tumour formation relies on a complex combination of genetic and environmental factors. In particular, the contributions from inherited predisposition genes as well as carcinogens, for example from cigarettes or in the diet, are amongst the major contributors to tumorigenesis. Since the study of such processes in particularly difficult in human cancers, the availability of a well-defined model system is of obvious benefit. The mouse skin model of multistage carcinogenesis offers an excellent tool for the study of the target cells, the target genes and the biological events associated with neoplasia. In this system, tumorigenesis occurs in a series of defined stages, each of which is characterized by specific and reproducible alterations in genes such as H-ras, cyclin D1, p53 and p16INK4A. Additional changes occur in the production of, or response to, factors such as transforming growth factor beta (TGF beta). These genetic and biological alterations are mirrored in human tumours of epithelial origin. Hence, research into the general principles of tumour initiation, promotion and progression in the context of the mouse skin model is likely to prove valuable in the continual search for new methods for the diagnosis, prevention, and therapeutic treatment of human cancers.

Animals↗
PubMed1998

Transforming growth factor beta is essential for spindle cell conversion of mouse skin carcinoma in vivo: implications for tumor invasion.

Transforming growth factor beta1 (TGF-beta1) regulates both cell growth and cellular plasticity and is therefore important in the molecular control of both the developmental and neoplastic processes. It has been suggested that TGF-beta1 may be a positive or negative regulator of tumorigenesis. Stimulation of tumorigenesis could be due to its action as an immunosuppressor or as an inducer of angiogenesis, or by its direct action on the cell in promoting cellular plasticity. In the current study, we provide evidence that TGF-beta1 can act directly on keratinocytes in vivo to induce the reversible epithelial-mesenchymal conversion of a malignant metastatic keratinocyte cell line. Two squamous clones from the cell line were shown to undergo a reversible conversion to a fibroblastoid phenotype after culture in 1 ng/ml TGF-beta1. The morphological conversion became apparent at 24 h post-TGF-beta treatment and was complete after another 24 h. The conversion was characterized by a rapid delocalization of E-cadherin within 6-12 h posttreatment, followed by down-regulation of E-cadherin levels by 72 h. These squamous clones spontaneously converted to a fibroblastoid phenotype after s.c. injection in nude mice. Importantly, four of four clones that had been stably transfected with a dominant negative TGF-beta type II receptor were unable to undergo this mesenchymal switch in vivo, despite the fact that all clones stably transfected with neomyocin resistance alone retained their spindle characteristics in vivo. This demonstrates that the epithelial-mesenchymal conversion event is mediated directly via the TGF-beta signaling pathway of the tumor cell per se, and that it is sufficient to significantly enhance tumorigenicity and the malignant and invasive characteristics of the tumor in vivo.

Animals↗
PubMed1996

Effects of heat shock on gram negative bacteria: use of lysis by sodium dodecyl sulphate as a probe for the integrity of DNA.

Rheograms of Alcaligenes eutrophus (NCIMB 40529) and Escherichia coli (C90 NCIMB 10616) cells lysed by sodium dodecyl sulphate were compared before and after a variety of heat shock regimes. It was found that unheated cells produced a very characteristic shear thickening rheogram which could be destroyed by DNase treatment. Cells which had been subjected to heat shock produced rheograms very similar to DNase digested material. We thus suggest that the rheogram is largely due to the presence of intact DNA molecules. The extent and nature of the heat shock affected the shape of the rheogram of the SDS lysed material. Heat shock of cells after SDS lysis did not appear to significantly damage the DNA. Storage of the cells at 10 degrees C before heat shock considerably reduced the shear thinning effect of subsequent heat shock at 90 degrees C. We attribute the shear thinning effect of the heat shock to the action of nucleases which are activated and then depolymerise the DNA molecules.

Alcaligenes↗
PubMed1987

Dietary intakes of phytate and its meal distribution pattern amongst staff and students in an institution of higher education.

1. Seventy-six students and staff at Robert Gordon's Institute of Technology weighed all items of food consumed for 1 week. 2. Mean phytate-phosphorus intakes ranged from 141 mg for female students to 237 mg for male students. Breakfast was proportionally a more important contributor to daily phytate intakes than to calcium, zinc, and energy intakes. Cereals were the most important contributors to the phytate at breakfast, whilst wholemeal and brown bread were more important at lunch and the evening meal. 3. The phytate: Zn molar ratio was distributed amongst meals similarly to the more complex ratio, (Ca x phytate):(Zn x energy) (CP:ZE); both ratios have been suggested as useful predictors of Zn availability. CP:ZE ranged more widely when calculated for meals than for days, and therefore some meals could be associated with poor Zn availability whilst others could compensate with higher availability. Subjects with the highest values for CP:ZE were mostly amongst the group of nutrition students.

Adult↗
PubMed1975

Validity of a screening test for typing serum cholinesterase variants among Greek populations.

A screening method for determining the abnormal phenotypes of human serum cholinesterase variants in a population survey was investigated. The test appeared to be satisfactory in detecting abnormal genotypes, but not assigning them into correct classification. The results of the population survey indicate that there may be a higher frequency of ChU1ChD1 genotype than those reported earlier. Family studies of the suxamethonium-sensitive propositi in this population demonstrate that abnormal genes ChD1, ChF1 and ChS1 are segregating, according to the usual Mendelian type of inheritance pattern. The possibility of a relatively high frequency of these abnormal genotypes among the Greek population has been indicated.

Cholinesterases↗
PubMed1970

Purification and properties of human serum cholinesterase.

Cholinesterase was purified from human serum by a three-stage procedure involving chromatography on DEAE-cellulose at pH4.0, an electrofocusing technique and gel filtration on Sephadex G-200. The final product was purified 13000-fold with a yield of 54%, and only one protein and one cholinesterase band could be demonstrated by polyacrylamide-disc electrophoresis. The catalytic properties appeared to be unchanged by the purification procedure. The molecular weight was determined by both ultracentrifugation in a density gradient and gel filtration, and values close to 366000 were obtained. The isoelectric point of cholinesterase was estimated to be pH3.99. The method appears suitable for the preliminary purification of the rare genetic variants of human cholinesterase.

Blood Protein Electrophoresis↗
PubMedDate not supplied

Molecular mechanisms of invasion and metastasis during mouse skin tumour progression.

The ultimate stage of carcinogenesis in both human and mouse epithelial cells is the ability to invade surrounding tissues and metastasize to distant sites. In mouse skin tumours, the development of the invasive, spindle cell phenotype is associated with an imbalance of alleles on mouse chromosome 7, including the H-ras gene. In previous work, we have described clonally related squamous and spindle cell lines from the same primary tumour which differed substantially in morphology and behaviour, but showed the same series of mutations in H-ras and p53 genes. One of the events which takes place during this transition is disruption of cell-cell contacts, possibly due to the induced expression of metalloproteinases such as stromelysin-1 and disappearance of the cell adhesion molecule E-cadherin. Parallel studies using somatic cell hybrids have shown that the spindle cell phenotype is recessive in hybrids between squamous and spindle cells. We propose that an important epidermal differentiation-controlling gene is lost during the spindle cell transition.

Animals↗