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Biomedical subjects

S Fleming

Publications and source records attributed to S Fleming.

At least 91 records · Page 5Linked to original sources
PubMed1995

Retrograde intramedullary nailing for ankle arthrodesis.

This is a retrospective study of retrograde intramedullary rodding for ankle arthrodesis in 19 ankles in 16 patients. The preoperative diagnosis of 16 patients was diabetic neuropathic arthropathy in seven patients, rheumatoid arthritis in three patients, post traumatic arthrosis in three patients, paraplegia with fixed equinovarus of the foot in two patients, and avascular necrosis of the talus in one patient. Retrograde intramedullary rodding for ankle arthrodesis was done as a salvage procedure in each patient. Fourteen of the 19 ankles had radiographic evidence of solid arthrodesis. In the four patients with five ankles with pseudarthrosis, no case was clinically significant. There was one deep infection and one broken rod. Thirteen of the 16 patients are ambulatory, and nine required either an ankle-foot orthosis or shoe modification. The standard method of ankle fusion using crossed cancellous screws is the procedure of choice because it preserves the subtalar joint. Retrograde intramedullary rodding for ankle arthrodesis should be considered for patients with significant posttraumatic arthrosis and bone loss following distal tibial plafond fractures, concomitant subtalar arthrosis, severe osteopenia, such as in patients with rheumatoid arthritis, or neuropathic arthropathy.

Adolescent↗
PubMed1994

Long-term survival of the exon 10 insertional cystic fibrosis mutant mouse is a consequence of low level residual wild-type Cftr gene expression.

Recently we have created a mouse model of cystic fibrosis (CF) by insertional gene targeting to exon 10. In common with CF subjects, this model displays a low incidence of meconium ileus. This contrasts strikingly with the very high level of fatal intestinal obstruction in the three other CF mouse models so far described. We investigate here the molecular basis of this difference in phenotype. We show that the partial duplication consequent upon insertional gene targeting allows exon skipping and aberrant splicing to produce normal Cftr mRNA, but at levels greatly reduced compared with wild-type mice. Furthermore, instead of the predicted mutant Cftr transcript, a novel mRNA is produced that utilizes cryptic splice sites in the disrupting plasmid sequence. However, we have previously shown that these mice display the ion transport defect characteristic of CF, and mutant animals can be distinguished from their normal littermates on this basis. Consistent with this, residual CFTR function has recently been observed for several "mild" mutations in CF individuals who display pancreatic sufficiency but still develop lung disease. We conclude that (i) residual wild-type mRNA in the exon 10 insertional mutant mouse ameliorates the severity of the intestinal phenotype observed in the absolute "null" CF mice, (ii) the presence of low-level residual wild-type Cftr mRNA does not correct the CF ion transport defect, and (iii) the long-term survival of this insertional mutant mouse provides the opportunity to address the factors important in development of lung disease.

Animals↗
PubMed1994

Sperm function and its manipulation for microassisted fertilization.

Comprehension of the intricate complexities of sperm function is clearly crucial to the success of attempts to manipulate it for the purposes of assisted conception. This is particularly important when considering various procedures for microassisted fertilization since these bypass critical physiological events that are mandatory for normal fertilization, to varying degrees. Methylxanthine derivatives such as pentoxifylline are useful agents for the management of oligoasthenozoospermic patients. This is particularly so for procedures such as SUZI where adequate motility of spermatozoa injected into the perivitelline space is crucial for fusion with the vitelline membrane to achieve fertilization. The generation of minute concentrations of reactive oxygen species in vitro may prove to be a valuable technique in this respect, in the light of recent evidence for their involvement in capacitation and hyperactivation. Induction of the acrosome reaction by non-invasive, non-toxic agents should markedly improve success rates for microassisted fertilization. Acrosin appears to play a central role in this and, therefore, it would seem prudent to monitor levels of acrosin activity in samples of spermatozoa used in assisted conception procedures. With respect to microassisted fertilization, the potential to select recently acrosome-reacted spermatozoa coated by activated acrosin promises to be a major improvement. Current methods employed for determination of the fertilization potential of spermatozoa are clearly inadequate (Polansky and Lamb, 1988; Aitken, 1990). In fact, the prevailing evidence suggests that no single parameter of sperm function reflects this potential (Zaneveld and Jeyendran, 1988). Therefore, we have both a scientific and a moral responsibility to investigate these processes further. Subsequently, we should be in a position to identify individual gametes with the potential for fertilization and so utilize procedures that result in maximal fertilization rates with minimal risk of polyploidy or abnormality.

Autoantibodies↗
PubMed1994

Spontaneous development of malignant phase hypertension in transgenic Ren-2 rats.

Spontaneous development of malignant phase hypertension in TGR(mREN2)27 heterozygotes occurs as a consequence of crossing TGR(mREN2)27 homozygotes with Edinburgh Sprague-Dawley rats. Similarities to human malignant phase hypertension are seen with an accelerated rise in blood pressure, fibrinoid necrosis of renal afferent arterioles, renal failure and evidence of renin-angiotensin system activation. It appears that introduction of an additional genetic factor or factors into a monogenic model of hypertension results in malignant phase hypertension.

Animals↗
PubMed1994

Expression of tissue kallikrein in human kidney.

1. We studied the distribution of human tissue kallikrein mRNA in normal and diseased kidney, using in situ hybridization, together with immunohistochemical localization of renal kallikrein protein. Materials studied were (a) normal tissue from kidneys removed because of localized renal carcinoma, (b) kidneys removed because of post-traumatic haemorrhage and (c) renal biopsy specimens from patients with membranous glomerulonephritis and nephrotic syndrome. 2. A 1.35 kb EcoRI fragment of human tissue kallikrein cDNA was labelled with [32P]dCTP using the random-primer technique, and used for in situ hybridization. A specific rabbit antibody to active human urinary kallikrein was employed for immunocytochemistry, using a peroxidase-antiperoxidase method. 3. By in situ hybridization, no tissue kallikrein gene expression was seen in the carcinoma nephrectomy specimens. Positive expression was seen in the trauma nephrectomy tissue, and in four of five nephrotic syndrome biopsies. In all kidneys, expression was confined to the renal cortex. The dominant site of gene expression was the distal tubule. Apart from one area of positive signal related to an epithelial cell of Bowman's capsule, expression was not observed in glomeruli. Expression was also seen in the walls of large- and medium-sized blood vessels. 4. By immunohistochemistry, the dominant site of immunoreactivity was the distal tubule. Dense staining was also seen in granular peripolar cells and in isolated parietal epithelial cells close to the vascular pole. Isolated immunoreactive cells were seen in the media of large- and medium-sized arteries. 5. The tissue kallikrein gene in the kidney may not be constitutively expressed, but is expressed in response to physiological or pathological stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Somatic mutations of the von Hippel-Lindau disease tumour suppressor gene in non-familial clear cell renal carcinoma.

Loss of heterozygosity (LOH) studies have suggested that somatic mutations of a tumour suppressor gene or genes on chromosome 3p are a critical event in the pathogenesis of non-familial renal cell carcinoma (RCC). Germline mutations of the von Hippel-Lindau (VHL) disease gene predispose to early onset and multifocal clear cell renal cell carcinoma, and the mechanism of tumorigenesis in VHL disease is consistent with a one-hit mutation model. To investigate the role of somatic VHL gene mutations in non-familial RCC, we analysed 99 primary RCC for VHL gene mutations by SSCP and heteroduplex analysis. Somatic VHL gene mutations were identified in 30 of 65 (46%) sporadic RCC with chromosome 3p allele loss and one of 34 (3%) tumours with no LOH for chromosome 3p. The VHL gene mutations were heterogeneous (17 frameshift deletions, eight missense mutations, four frameshift insertions, one nonsense and one splice site mutation), but no mutations were detected in the first 120 codons of cloned coding sequence. Most RCCs with somatic VHL mutations (23 of 27 (85%) informative cases) had chromosome 3p25 allele loss in the region of the VHL gene so that both alleles of the VHL gene had been inactivated as expected from a two-hit model of tumorigenesis. Detailed histopathology was available for 59 of the tumours investigated: 18 of 43 (42%) RCC with a clear cell appearance had a somatic VHL gene mutation but none of 16 non-clear cell RCC (eight chromophilic, three chromophobe and five oncocytoma) (chi2 = 7.77, P < 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma, Clear Cell↗
PubMed1994

Intrarenal localization of interleukin-1 beta mRNA in crescentic glomerulonephritis.

Il-1 beta is a potent proinflammatory peptide, and induces expression of other cytokines which are involved in the immune response. Kidney biopsies from nine patients with crescentic GN were studied by in-situ hybridization to determine the site of expression of Il-1 beta mRNA. Biopsies from nine patients with nonproliferative renal disease were studied as negative controls, and tonsillar tissue was studied as a positive control. An Il-1 beta cDNA probe was 32P-labelled by random primers and hybridized to paraffin-embedded tissue sections after de-waxing. Il-1 beta mRNA was expressed in tonsil, but not in negative controls. Positive mRNA expression was seen in four of the nine crescentic biopsies. This was observed in interstitial cells with morphological characteristics of macrophages adjacent to tubular cells, in cells within the glomerular tuft, and in tubular epithelial cells. Il-1 beta mRNA is expressed in renal tissue in crescentic GN. Tubular and interstitial expression of Il-1 beta mRNA appears of equal prominence to glomerular expression. Intrarenal cytokine synthesis may be involved in the pathogenesis of crescentic glomerulonephritis.

Adult↗
PubMed1994

Idiopathic megacolon in the BB rat.

It has been assumed that idiopathic megacolon occurring in the spontaneously diabetic BB rat results from metabolic decompensation associated with diabetes. In a large prospective necropsy study we have documented the incidence of idiopathic megacolon and its distribution between diabetic and non-diabetic animals in the BB rat colony in Edinburgh. A significantly increased incidence of megacolon was found in non-diabetic rats in the diabetes-prone subline compared with diabetic rats in the diabetes-prone subline and with non-diabetic rats in the diabetes-resistant subline. Affected animals were found to have an inflammatory infiltrate in the wall of the large bowel with destruction of both autonomic ganglia and muscularis propria. These necropsy observations indicate that megacolon cannot be a result of the metabolic disturbance due to the hyperglycaemia associated with diabetes.

Age Factors↗
PubMed1993

Metabolic requirements for phorbol ester-induced cytoskeletal changes in renal epithelium.

Alteration of the cytoskeleton and cell-substratum adhesion are important in the progression of renal carcinoma. We have previously shown that treatment of normal human renal epithelium with phorbol esters mimics the changes seen in renal carcinoma cells. In this study we have demonstrated that the phorbol ester-induced cytoskeletal reorganization is inhibited in the presence of deoxyglucose but not by cycloheximide. We have also shown that treatment of cells with cytochalasin B results in the formation of immature stress fibres restricted to the cell-substratum contact regions. These results suggest that the actin filaments elongate from the focal contacts and that structural rearrangement caused by phorbol esters is an energy-dependent phenomenon but is independent of de novo protein synthesis.

Cells, Cultured↗
PubMed1993

The specificity of integrin-ligand interactions in cultured human renal epithelium.

Members of the beta 1 integrin family are present at the basolateral membrane of human renal tubular epithelium in vivo and at the ventral surfaces of cultured renal epithelial cells, at the sites appropriate for cell substratum adhesion. In this study we have proven that these molecules are indeed functional in mediating cell substratum attachment in normal human renal epithelium by using monoclonal antibodies to integrin alpha subunits to block initial cell attachment. The importance of arginine-glycine-aspartic acid (RGD) recognition by cell surface receptors in various extracellular ligands was also examined using synthetic peptides. RGDS peptide strongly inhibited attachment to plain plastic or fibronectin-coated substrata but had no effect on cell adhesion to laminin-coated coverslips.

Cell Adhesion↗
PubMed1993

Intra-abdominal desmoplastic small round cell tumor.

A rarely encountered but distinctive type of aggressive malignant tumor of childhood and adolescence has been recently described as occurring predominantly or exclusively intrabdominally. It is characterized by a generally diffuse pattern of growth of small cells with hyperchromatic nuclei, scanty cytoplasm, patchy epithelial differentiation, immunohistochemical co-expression of keratin and desmin intermediate filaments and a focal but pronounced desmoplastic stromal component. It is regarded as yet another variant in the group of small round cell tumors (SRCT) of infancy and childhood. This case report of a mass in the greater omentum of a 15 yr-old girl adds to the 33 cases already described in the English literature.

Adolescent↗
PubMed1992

Cystic fibrosis in the mouse by targeted insertional mutagenesis.

Cystic fibrosis is a fatal genetic disorder which afflicts 50,000 people worldwide. A viable animal model would be invaluable for investigating and combating this disease. The mouse cystic fibrosis transmembrane conductance regulator gene was disrupted in embryonal stem cells using an insertional gene targeting vector. Germ-line chimaeras were derived and the offspring of heterozygous crosses studied. These homozygous mutant mice survive beyond weaning. In vivo electrophysiology demonstrates the predicted defect in chloride ion transport in these mice and can distinguish between each genotype. Histological analysis detects important hallmarks of human disease pathology, including abnormalities of the colon, lung and vas deferens. This insertional mouse mutation provides a valid model system for the development and testing of therapies for cystic fibrosis patients.

Animals↗
PubMed1992

Survey for drug-resistant gastrointestinal nematodes in 13 commercial sheep flocks.

The prevalence of drug-resistant ovine parasites in the United States has not been widely reported. Thirteen flocks, typical of commercial sheep production units, were selected for survey. Four anthelmintics (fenbendazole, ivermectin, pyrantel pamoate, and levamisole) were tested for their ability to reduce herd mean pretreatment fecal egg count. If a properly dosed and administered drug failed to reduce herd mean pretreatment fecal egg count by 80%, it was considered ineffective in that flock, and the presence of parasites resistant to that drug was inferred. Fenbendazole administration changed pretreatment fecal egg counts by +9% to -100%. On the basis of the aforementioned definition, drug resistance existed in 6 of 13 flocks. Posttreatment larval culture indicated that Haemonchus contortus survived administration of fenbendazole. Levamisole, pyrantel pamoate, and ivermectin reduced pretreatment fecal egg count by -83% to -100%; resistance to these products was not evident in the flocks surveyed.

Animals↗