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Biomedical subjects

M Leader

Publications and source records attributed to M Leader.

At least 19 recordsLinked to original sources
PubMed2003

Biopsy of a biopsy: validation of immunoprofiling in gastric cancer biopsy tissue microarrays.

AIMS: Tissue microarrays offer an efficient way of examining a large number of tumour cases on a single glass slide. A major concern, however, is tumour heterogeneity. Also, the use of tissue microarrays in biopsy material is unexplored. The purpose of the present study was to assess the possibility and validity of arraying three 0.6-mm cores per case in endoscopic gastric cancer biopsies for immunophenotyping. METHODS AND RESULTS: Thirty-eight cases were studied with immunohistochemical staining for p53, CD44v6 and vascular endothelial growth factor. Full tissue sections were compared with triple core-tissue microarrays. Thirty-six cases contained three cores with tumour, one case contained two cores with tumour and one case contained only a single core with viable tumour and was excluded. Three further cores had been lost from three separate cases on the sections for immunohistochemistry. kappa values for whole-sections versus tissue microarrays ranged between 0.77 and 0.94. p53 immunohistochemical staining (interpretation as + or -) yielded the best result with only 1/37 mismatches, whereas CD44v6 (graded both for intensity and extent) showed 3/37 mismatches. The small depth of tissue in cores from biopsies necessitates all cores being arrayed flush with the face of the recipient wax block for maximizing the number of sections available. Compared with the first section over 30 additional 4- micro m sections were available before the first case (with one core left) had to be excluded and 80 sections before half the tissue cores were lost. CONCLUSIONS: It is impracticable to array more than 120-150 cores per block. Tissue microarray with three cores per case is feasible and valid for studying biopsy material.

Adult↗
PubMed2003

Chronic osteomyelitis mimicking sarcoma.

This report describes a rare case of chronic osteomyelitis in a 60 year old man mimicking a soft tissue sarcoma. Chronic osteomyelitis is an infrequent cause of a soft tissue mass and is usually diagnosed clinically by a combination of radiology and microbiology. Rarely, COM can mimic a primary bony neoplasm, but this is the first reported case where it mimicked a soft tissue sarcoma. The clinical, radiological, and histological appearances of this case will be discussed.

Chronic Disease↗
PubMed2002

The expression of p53, p21, Bax and induction of apoptosis in normal volunteers in response to different doses of ultraviolet radiation.

BACKGROUND: Ultraviolet radiation (UVR) damages keratinocytes. Direct DNA damage may undergo enzymatic repair followed by resumption of the normal cell cycle. Cells may also be eliminated without inflammation by the error-free process of programmed cell death or apoptosis. Necrosis of cells can occur after overwhelming damage. Failure of apoptosis leads to retention of cells with persistent mutations. OBJECTIVES: This study investigates p53-dependent apoptotic responses in normal skin following solar-simulated radiation (SSR). METHODS: Sun-protected buttock skin from normal volunteers with no history or clinical evidence of skin cancer was exposed to graded doses of SSR, 0.5, 1, 2 and 3 times the minimal erythema dose (MED). Biopsies taken at a range of time points (4.5, 9, 24, 33, 48 and 72 h) after UVR, quantified the time course and dose-response of apoptosis and the expression of the relevant proteins, p53, p21waf1/Cip1 and Bax, by single and double labelling techniques. RESULTS: Apoptosis was upregulated in a dose-dependent manner as was the expression of p53, p21waf1/Cip1 and Bax in response to SSR. Following exposure to 3 MEDs it was found that: (i) the maximum number of apoptotic cells occurred at 48 h; (ii) p53 protein expression was upregulated from 4 to 72 h preceding peak p21waf1/Cip1 protein expression (9-48 h) and peak Bax protein expression (33 h). CONCLUSIONS: These results suggest that, following SSR, normal human skin induces apoptosis by the p53, p21waf1/Cip1, Bax pathway in vivo. In addition, induction of apoptosis and expression of p53, p21waf1/Cip1 and Bax occurs in a dose-dependent manner.

Aged↗
PubMed2002

Comparative study: conventional cervical and ThinPrep Pap tests in a routine clinical setting.

The conventional Papanicolaou smear is associated with variable false positive and false negative rates, difficulties with interpretation and high unsatisfactory and suboptimal rates. Newer fluid-based methods such as the ThinPrep 2000 system (Cytyc Corp., Boxborough, MA) are said to overcome these difficulties. The aim of this study was to compare the conventional smear with the ThinPrep method in a busy, routine cytology screening laboratory setting. One thousand split samples were evaluated. Using ThinPrep, the results showed an increased sensitivity and a dramatic improvement in specimen adequacy, with a combined 17.2% reduction in 'unsatisfactory' and 'suboptimal' reports. Screening time per slide was also reduced to 3-4 min. In conclusion, we report an increase in sensitivity, a reduction in screening time and a dramatic improvement in specimen adequacy with the ThinPrep method.

Cell Nucleus↗
PubMed2002

APC gene expression in gastric carcinoma: an immunohistochemical study.

Gastric carcinoma is one of the most common malignancies worldwide, particularly in Japan and China. Inactivation of the adenomatous polyposis coli ( ) gene, a tumor suppressor gene, has been shown to play a significant role in the development of colorectal carcinoma, and it has been suggested that it may play a role throughout the digestive tract, including the stomach. This study assesses gene expression in normal gastric mucosa and gastric adenocarcinoma using an antibody to the C-terminal region. One hundred twenty cases of gastric adenocarcinoma were examined from the files of Beaumont Hospital, Dublin, Ireland, and China Medical University, Shenyang, China. Ninety-one cases were informative. Of these, 78% revealed loss of staining. Loss of staining in adenocarcinoma showed no association with tumor type, tumor, stage or patient nationality. Loss of staining was also found in nine of 35 cases (26%) of intestinal metaplasia. In conclusion, loss of the gene, as determined by immunohistochemical staining, appears to be an early event in gastric carcinogenesis. Immunohistochemistry is a sensitive method for detection of this loss.

Adenocarcinoma↗
PubMed2002

Comparison of the expression of p53, p21, Bax and the induction of apoptosis between patients with basal cell carcinoma and normal controls in response to ultraviolet irradiation.

AIM: Ultraviolet light (UV) is known to cause DNA damage in the epidermis. The damaged DNA is repaired or deleted by apoptosis to prevent the generation of cancer. It has been suggested that a deficient apoptotic mechanism may predispose individuals to skin cancer. Therefore, the response of normal controls and patients with basal cell carcinoma (BCC) to UV irradiation was investigated. METHODS: The buttock skin from normal volunteers and patients with BCC was irradiated using solar simulated radiation (SSR). SSR mimics the effect of natural sunlight. Skin biopsies were excised and examined for p53, p21, and Bax protein expression and for the induction of apoptosis. RESULTS: At 33 hours after UV irradiation, the induction of apoptosis was significantly higher (p = 0.04) in patients with BCC than in normal volunteers (Mann Whitney test). A trend towards higher p21 expression was found at 33 hours in patients with BCC (mean, 18.69 positive cells/field) than in normal volunteers (mean, 9.89), although this difference was not significant (p = 0.05 positive cells/field). CONCLUSION: These results may imply that patients with BCC have enhanced sensitivity to UV irradiation or that there is some defect in the cell arrest or repair pathways, which results in damaged cells been pushed into apoptosis rather than repair.

Apoptosis↗
PubMed2002

Telomerase activity detected in oral lichen planus by RNA in situ hybridisation: not a marker for malignant transformation.

BACKGROUND: Oral lichen planus (OLP) is a chronic inflammatory condition. Clinically, it is characterised by the presence of a white lace-like lesion on the buccal mucosa, tongue, and gingivae, with erosions and ulceration. The World Health Organisation considers OLP to be a premalignant condition. AIMS: To investigate expression of the telomerase RNA component (hTR) in OLP compared with normal control buccal mucosa and to assess the possibility of using hTR expression as a marker for malignant transformation in OLP. METHODS: hTR expression was analysed in 40 cases of OLP and 18 normal control buccal mucosa samples using an RNA in situ hybridisation approach. RESULTS: Strong hTR RNA expression was seen in the basal, suprabasal, and to a lesser extent in the upper epithelial layers in 36 of the 40 OLP lesions examined. Infiltrating subepithelial lymphocytes in OLP were also shown to express hTR RNA. Weak hTR RNA expression was seen in seven of the 18 normal control buccal mucosa specimens, with expression confined exclusively to the basal layer of the epithelium and absent in the suprabasal and upper layers. CONCLUSION: The telomerase RNA component hTR is found to be highly expressed in the epithelium of non-dysplastic OLP lesions. It is possible that this high expression is related to the increased cellular proliferation seen in OLP lesions rather than being an indicator of susceptibility to malignancy. Thus, hTR RNA expression may not be a suitable marker for predicting malignant transformation in OLP.

Adult↗
PubMed2001

Altered p53 expression in benign and malignant skin lesions from renal transplant recipients and immunocompetent patients with skin cancer: correlation with human papillomaviruses?

Renal transplant recipients are prone to numerous benign and malignant skin lesions. Previous work in the authors' laboratory has determined that the human papillomavirus may be the viral aetiology of these skin lesions. The p53 tumor-suppressor gene is the most frequently mutated gene in a wide range of human cancers. Here the authors describe an immunohistochemical study to evaluate the expression of p53 in benign and malignant skin lesions from renal transplant recipients and immunocompetent patients with skin cancer. The effect of p53 mutations on the expression patterns observed were examined by polymerase chain reaction-single strand conformation polymorphism analysis and direct cycle sequencing. The expression of the p53-regulated cyclin-dependant kinase inhibitor p21Waf1/Cip1 and Mdm2 was also examined in p53-positive cells. The expression of p53 in benign and malignant lesions was found to be markedly different. p53 was expressed in only 40% (6/15) of viral warts analyzed. The expression was confined to the basal layer both in the lesion and in adjacent normal skin, and the level of expression was low and only in a small number of cells (<10%). Of the cutaneous squamous cell carcinomas analyzed, 60% (9/15) showed p53 expression. Two different patterns of expression were observed. Basal layer expression in both the invasive tumor and adjacent normal skin was observed in 50% of the p53-positive squamous cell carcinomas; in the remaining 50%, p53 was expressed diffusely throughout the invasive tumor and in the basal layer of adjacent normal skin. The level of expression was high and in a large number of cells. Polymerase chain reaction-single strand conformation polymorphism analysis revealed that only one of the squamous cell carcinomas expressing p53 harbored a p53 mutation and that the accumulated p53 in the remaining tumors was wild type. No Mdm2 or p21Waf1/Cip1 expression was detected in the p53-positive squamous cell carcinomas, indicating that although the accumulated p53 is stable, it does not function effectively as a transcriptional activator. This represents a novel p53 phenotype in cutaneous squamous cell carcinoma. In addition, no correlation was seen between the presence and absence of human papillomavirus and p53 expression.

Carcinoma, Squamous Cell↗
PubMed2001

p53 codon 72 polymorphism and human papillomavirus associated skin cancer.

BACKGROUND/AIMS: Non-melanoma skin cancers frequently harbour multiple human papillomavirus (HPV) types. A recent report suggests that a polymorphism of the p53 tumour suppressor gene that results in the substitution of a proline residue with an arginine residue at position 72 of the p53 protein might act as a risk factor in HPV associated malignancies. This study aimed to determine the following: (1) the relation between HPV infection and the development of cutaneous squamous cell carcinoma (SCC), and (2) whether there is a correlation between p53 codon 72 polymorphism and the development of SCC. METHODS: Blood samples were taken from 55 patients with skin cancer (both renal transplant recipients and immunocompetent patients with skin cancer) and 115 ethnically matched volunteers. A polymerase chain reaction based assay was used to determine p53 codon 72 genotypes. In addition, 49 benign and malignant lesions from 34 of the patients with skin cancer and 20 normal human skin samples from 20 of the control volunteers were examined for HPV. RESULTS: The proportions of p53 codon 72 genotypes found were 78% arginine homozygous, 2% proline homozygous, and 20% heterozygous among patients with skin cancer and 79% arginine homozygous, 3.5% proline homozygous, and 17.5% heterozygous among the control population. Statistical analysis showed no significant differences in the distribution of the two p53 isoforms between the patients with skin cancer and the control population. The predominant viral types detected in both the patients and the control group were EV associated HPVs, although the incidence was lower in normal skin samples than in malignant lesions or viral warts. CONCLUSIONS: These results suggest that in a Celtic population there is no correlation between the presence of HPV, the p53 codon 72 arginine polymorphism, and the development of skin cancer.

Carcinoma, Squamous Cell↗
PubMed2001

A high degree of chromosomal instability at 13q14 in cutaneous squamous cell carcinomas: indication for a role of a tumour suppressor gene other than Rb.

BACKGROUND/AIMS: Loss of function of the retinoblastoma (Rb) tumour suppressor gene, located on chromosome 13, is common in many inherited and sporadic forms of cancer. Inactivation of its gene product by oncogenic human papillomaviruses (HPV) plays a key role in the genesis of cervical cancer. It has been shown previously that non-melanoma skin cancers of renal transplant recipients and immunocompetent patients with skin cancer also frequently harbour potentially oncogenic HPV types. This study aimed to examine the integrity of the Rb gene in histologically confirmed squamous cell carcinomas (SCCs) from renal transplant recipients and immunocompetent patients with skin cancer. METHODS: Loss of heterozygosity (LOH) at the Rb locus was examined in 13 histologically confirmed SCCs using the D13S153 microsatellite marker, which is located in exon 2 of the Rb gene. Loss of a second marker, D13S118, distal telomerically to the Rb gene at 13q14.3 was also analysed. RESULTS: Of the 13 HPV associated SCCs examined 11 were informative (two SCCs were homozygous for both microsatellite markers). LOH at the D13S153 locus was found in four of the 10 informative SCCs and LOH at the D13S118 locus was found in five of the 11 informative cases. Overall, seven of the 11 informative cases showed LOH at one or other locus. This represents a high degree of chromosomal instability in these tumours. The expression of the Rb gene product in the 11 informative cases was analysed immunohistochemically. Expression of Rb was detected in 10 of the 11 SCCs examined. No correlation between the HPV status of the tumours and the expression of Rb was found. Although the only SCC not to express Rb also demonstrated LOH at the D13S153 locus, the remaining SCCs that had LOH at 13q14 were able to express RB: CONCLUSION: Another tumour suppressor gene located at 13q14 might be responsible for the genesis of these tumours.

Carcinoma, Squamous Cell↗
PubMed2000

Swelling and delamination of multi-electrode sensor arrays studied by variable-pressure scanning electron microscopy.

Multi-electrode sensor arrays are made of soft and wet materials not easily examined by most microscopic techniques. In this paper, we have demonstrated that low-vacuum scanning electron microscopy (LVSEM) and energy-dispersive X-ray analysis (EDX) are adequate for studying the hydration, swelling, and possible delamination of multi-electrode sensor arrays. We found that the LVSEM environment had no detectable effect on the morphology of Na(+), K(+), and Ca(++) sensors, and EDX analysis indicated that all three membranes have similar compositions. However, once hydrated, the sensors exhibited different behaviors. The K(+) and Ca(++) sensors swelled more than the Na(+) sensor did. This swelling is due principally to water sorption in the membrane. We believe that the larger thickness of the K(+) and Ca(++) membrane is partly responsible for the observed swelling effect. A simple Griffith analysis of the interface rupture confirms the experimental evidence that these thicker membranes also are more prone to delamination failure.

Biocompatible Materials↗
PubMed2000

Deterioration of giant cell arteritis with corticosteroid therapy.

BACKGROUND: Failure of response of giant cell arteritis (GCA) to corticosteroid therapy has invariably been attributed to the delay in diagnosing the disease or the use of inadequate corticosteroid dosage. Following our observation of progressive deterioration following the introduction of prednisolone use in a patient, we examined the possibility that worsening of the condition might be due to corticosteroid therapy rather than coincidence. OBJECTIVE: To determine whether corticosteroid therapy may exacerbate GCA. DESLGN: Case report and an analysis of similar cases reported in the medical literature. PATIENT: A 64-year-old man had a 3-month history of headache, night sweats, malaise and general weakness, and anorexia and weight loss and a more recent history of jaw claudication, dysphagia, and hoarseness. Clinical findings included prominent temporal arteries with absent pulsation, abnormal saccades to the right, and eyelid retraction. Laboratory findings included an elevated erythrocyte sedimentation rate and platelet count. Results of a biopsy of the temporal artery confirmed GCA. Magnetic resonance imaging scans showed ischemic cerebellar lesions and a mature infarct in the left anterior occipital, posteroparietal region. Following corticosteroid therapy commencement, the patient's condition deteriorated steadily for 5 days with clinical signs suggestive of an evolving vertebrobasilar stroke. Following treatment with high-dose intravenous dexamethasone sodium phosphate and heparin sodium, his symptoms improved. DATA SOURCES: The review included analysis of autopsy-based reports in which clinical details are provided and clinical reports in which major visual or cerebral complications are described. Significant complications occurred in many cases shortly following the introduction of corticosteroid therapy. In many of these cases, the symptoms indicated that GCA had been present for a significant period prior to corticosteroid therapy. CONCLUSIONS: Progressively evolving occlusive strokes may occur following corticosteroid therapy in patients with GCA. In cerebrovascular complications, vascular occlusion occurs at sites of active vasculitis, usually within the vertebrobasilar system. It is not certain that the worsening of the condition following corticosteroid therapy is always coincidental, and an alternative possibility, namely a functional relationship between the initiation of corticosteroid therapy and clinical deterioration, should be borne in mind.

Adrenal Cortex Hormones↗
PubMed2000

Expression of CD44 in uterine cervical squamous neoplasia: a predictor of microinvasion?

OBJECTIVE: CD44, an integral membrane glycoprotein, may have an important role in early tumorigenesis, specifically, facilitating early tumor progression. Reports of the expression of CD44 in early uterine cervical squamous carcinogenesis are conflicting. We examined the expression of CD44 in microinvasive carcinoma of the cervix (MIC), as yet unreported, and compared it to that in cervical intraepithelial neoplasia (CIN) 1 and CIN 3 to further elucidate its role in early squamous carcinogenesis. METHODS: Seventeen cases of CIN 1, 24 cases of CIN 3, and 20 cases of MIC were stained with antibodies to CD44s, CD44v5, and CD44v6. Only membranous staining was considered positive. RESULTS: Positive membranous staining (>50% cells) was observed in 97% of cases of CIN 1 using all three antibodies. In CIN 3, positive staining was seen more often with CD44v6 (18/24) and CD44v5 (19/24) than with CD44s (6/24). Expression of CD44v6 was retained more often in MIC (16/20) compared with CD44s (3/20) and CD44v5 (9/20). Those cases of CIN 3 and MIC that failed to meet our criteria for positive staining showed either heterogeneous or absent staining. CONCLUSION: There is a qualitative and quantitative reduction in expression of CD44 in MIC and CIN 3 compared with CIN 1. Down-regulation of CD44 variants may occur later in neoplastic progression than CD44s. This pattern may reflect their important biological function in early progression by cervical cancer cells. Patchy and heterogeneous staining in more advanced lesions limits the usefulness of CD44 and its variants in the assessment of microinvasion.

Adult↗
PubMed2000

A simple and rapid technique for the detection of Epstein-Barr virus DNA in HIV-associated oral hairy leukoplakia biopsies.

A method of generating nucleic acid probes by polymerase chain reaction (PCR) for the detection of Epstein-Barr virus (EBV)-DNA by in situ hybridization in oral hairy leukoplakia (OHL) lesions is described. This method has the advantage over older methods of being cheaper, quicker and retaining sensitivity and specificity. Purified PCR products of Epstein-Barr virus DNA of 110 bp and 328 bp were labelled with biotin by nick translation or random primer labelling and were compared in in situ hybridization experiments with probes prepared by incorporation of biotin-labelled nucleotides in the PCR reaction mixture, with EBV viral DNA as a template. These probes were applied to 18 OHL tongue biopsies known to be positive for EBV-DNA, using a commercially available biotin-labelled BamHI "V" fragment EBV-DNA probe. To determine the specificity of the probes, we applied them to 20 normal tongue tissue samples and to 12 biopsies taken from keratotic tongue lesions from patients without risk factors for HIV infection and known to be negative for EBV-DNA. Clear positive signals for EBV-DNA were detected in all 18 cases of OHL biopsies using the amplimer of 328 bp labelled by PCR and random primer labelling. However, nick translation labelling was less efficient and sensitive. All control specimens were negative for EBV-DNA.

AIDS-Related Opportunistic Infections↗
PubMed2000

Point-of-need diagnosis of cystic fibrosis using a potentiometric ion-selective electrode array.

The novel approach of using a micro-sensor array of miniaturised solid-state ion-selective electrodes to analyse sweat samples for sodium, potassium and chloride simultaneously is described. The array, incorporated into a miniature flow cell which is linked to a portable PC for data acquisition, constitutes a small, portable, and simple to use analytical instrument. Samples are passed through the flow cell and over the array and an immediate potentiometric response is obtained, which can be equated to the concentrations of sodium, chloride, potassium and other parameters in the sweat sample. Used here in conjunction with a Wescor Macroduct sweat sampling unit, it promises a much simplified, much less expensive procedure for sweat analysis than the procedures currently in common use.

Chlorine↗
PubMed2000

Immunohistochemical measurement of tumor vascular endothelial growth factor in breast cancer. A more reliable predictor of tumor stage than microvessel density or serum vascular endothelial growth factor.

Microvessel density counting is commonly proposed as a method of assessing angiogenesis. However, results have been difficult to reproduce because of many methodological inconsistencies. Vascular endothelial growth factor (VEGF), an angiogenic regulator, is also a poor prognostic indicator in breast cancer, correlating in many studies with microvessel density. In this study, VEGF and microvessel density counting were examined as methods of assessing angiogenesis in breast cancer and correlated with tumor stage. A representative tumor section was stained with anti-CD34 and anti-VEGF. Microvessel density was evaluated using the manual "hot-spot" procedure and a semiquantitative image analysis system. Serum VEGF levels were available from an additional nine patients. Results were analyzed using Kendall's tau correlation. Tumor stage correlated with tumor VEGF, but not with microvessel "hot-spot" or vessel counts. There was no correlation between scores obtained from the manual or semiquantitative methods. Serum VEGF did not correlate with either tumor VEGF or tumor stage. The prognostic importance of VEGF in invasive breast cancer is associated with tumor stage. Measurement of tumor VEGF, as an indicator of angiogenesis, is more reliable prognostically than measurement of microvessel density or serum VEGF. Routine measurement of microvessel density in breast cancer is less reliable.

Adult↗
PubMed2000

Replication error phenotype, clinicopathological variables, and patient outcome in Dukes' B stage II (T3,N0,M0) colorectal cancer.

AIMS: To examine the relation between the replication error (RER) phenotype and other genetic events, clinical features, and long term survival in patients with Dukes' B stage II (T3,N0,M0) colorectal cancer. METHODS: RER phenotype was investigated in 159 patients by PCR amplification of microsatellite marker loci on chromosomes 5q, 17p, 17q, and 18q from tumour DNA extracted from archival tissue. Data on activating c-Ki-ras mutations were available from a previous study. Immunohistochemical detection of p53 and c-erbB-2 expression was performed on paraffin wax embedded tissue. RESULTS: Of 159 colorectal cancers studied, 22 (14%) were RER+ while 137 (86%) were RER- for two or more loci. RER+ tumours were more commonly located in the right colon, tended to be larger than RER- tumours, and were more often poorly differentiated than RER- cancers. No significant associations were seen between RER status and the presence of a mutant c-Ki-ras gene, or between RER status and p53, c-erbB-2, or c-myc gene expression. Univariate survival analysis showed that outcome was similar in RER+ and RER- cases. Multivariate survival analysis showed that the relative risk of death for patients with RER+ cancers was 0.95 that of patients with RER- cancers. CONCLUSIONS: The results suggest that, while the RER phenotype may be associated with some differences in tumour pathology (site, size, differentiation), it is not associated with the genetic alterations studied or with significant differences in long term survival.

Aged↗