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W R Otto

Publications and source records attributed to W R Otto.

At least 19 recordsLinked to original sources
PubMed2002

Calcium-activated potassium channel SK1- and IK1-like immunoreactivity in injured human sensory neurones and its regulation by neurotrophic factors.

Calcium-activated potassium ion channels SK and IK (small and intermediate conductance, respectively) may be important in the pathophysiology of pain following nerve injury, as SK channels are known to impose a period of reduced excitability after each action potential by afterhyperpolarization. We studied the presence and changes of human SK1 (hSK1)- and hIK1-like immunoreactivity in control and injured human dorsal root ganglia (DRG) and peripheral nerves and their regulation by key neurotrophic factors in cultured rat sensory neurones. Using specific antibodies, hSK-1 and hIK-1-like immunoreactivity was detected in a majority of large and small/medium-sized cell bodies of human DRG. hSK1 immunoreactivity was decreased significantly in cell bodies of avulsed human DRG (n = 8, surgery delay 8 h to 12 months). There was a decrease in hIK1-like immunoreactivity predominantly in large cells acutely (<3 weeks after injury), but also in small/medium cells of chronic cases. Twenty-three injured peripheral nerves were studied (surgery delay 8 h to 12 months); in five of these, hIK1-like immunoreactivity was detected proximally but not distally to injury, whereas neurofilament staining confirmed the presence of nerve fibres in both regions. These five nerves, unlike the others, had all undergone Wallerian degeneration previously and the loss of hIK1-like immunoreactivity may therefore reflect reduced axonal transport of this ion channel across the injury site in regenerated fibres, as well as decreased expression in the cell body. In vitro studies of neonatal rat DRG neurones showed that nerve growth factor (NGF) significantly increased the percentage of hSK1-positive cells, whereas neurotrophin 3 (NT-3) and glial cell line-derived neurotrophic factor (GDNF) failed to show a significant effect. NT-3 stimulated hIK1 expression, while NGF and GDNF were ineffective. As expected, NGF increased expression of the voltage-gated sodium channel SNS1/PN3 in this system. Decreased retrograde transport of these neurotrophic factors in injured sensory neurones may thus reduce expression of these ion channels and increase excitability. Blockade of IK1-like and other potassium channels by aminopyridines (4-AP and 3,4-DAP) may also explain the paraesthesiae induced by these medications. Selective potassium channel openers are likely to represent novel therapies for pain following nerve injury.

Adult↗
PubMed2001

Molecular and cellular analysis of embryonic avian tongue development.

Signalling cascades first described in Drosophila have been found to regulate patterning and outgrowth in a number of structures in higher vertebrates. We sought to determine whether the evolutionarily conserved genes were important during the development of the tongue. In situ hybridisation was used to determine the temporo-spatial expression of a panel of conserved genes. Histological examination and incorporation of BrdU were used to determine the mechanism by which the tongue develops. We show that evolutionarily conserved genes were expressed in distinct dynamic patterns during tongue development. Sonic Hedgehog (Shh) and Patched (Ptc) were found only in the dorsal tongue epithelium. Shh expression was only observed in the suprabasal layers, whereas Ptc was observed in both basal and suprabasal layers. Cell division in the epithelium was concentrated in regions devoid of Shh. Expression of bone morphogenetic protein-7 (BMP) was identical to that of Shh. Shh and Ptc expression were never detected in the mesenchyme. Ectopic expression of Noggin (a potent antagonist of the BMPs) caused severe abnormalities in tongue morphology, including swelling of the mesenchymal component and a thickening of the epithelial layer. Data from this study suggests that the epithelium and mesenchyme express quite different genes during development. However BMP activity acts to inhibit growth in both tissues.

Activins↗
PubMed1999

Trefoil factor family (TFF)-domain peptides in the mouse: embryonic gastrointestinal expression and wounding response.

Trefoil factor family (TFF)-domain peptides are mucin-associated molecules that play a role in maintaining gastrointestinal (GI) epithelial integrity. They are expressed in specific patterns in adult mammals, but their embryonic expression has not been clarified. Developmental TFF mRNA in mice was studied by non-isotopic whole mount in situ hybridization. All TFF's (1-3) were seen in the stomach from E13 to E16. TFF1 was gastric at E13, then spread to the small intestine (E15) and caecum on E16. Froin E19 TFF1 expression was gastric. TFF2 was gastric at E13, and absent in lower intestines till E17 when duodenal, small intestinal and caecal expression was seen. Afterwards, TFF2 was confined to the gastric region. TFF3 was in the stomach at E13. On E15 and 16 TFF3 was ubiquitous, except for E15 caecum. From E17, TFF3 was confined to small intestine and the distal gut. WOUNDS: E17 and 18 GI tissues were subjected to incisional wounds in vitro. TFF1 induction was seen only in stomach, after as short as 30 min incubation. TFF2 was only induced at E18 in the stomach. TFF3 was induced within 5 min in the rectum. No change in overall expression patterns were seen after wounding. CONCLUSIONS: TFF expression is developmentally controlled in the GI tract, and appears before mucous cell differentiation in several tissues. Gene regulation is predicted to be under different control(s) in utero compared with post-natal life. The response to incisional wounding of fetal GI tissue shows differences to the adult.

Animals↗
PubMed1997

Rolling in the clover: trefoil factor family (TFF)-domain peptides, cell migration and cancer.

Trefoil factor family (TFF)-domain peptides 1-3 are mucin-associated molecules, largely found in epithelia of gastrointestinal tissues. Structurally similar, resistant to enzymatic degradation, they are up-regulated around areas of epithelial damage such as ulcers. Transgenic expression or exogenous peptide ameliorates or prevents gastric mucosal damage due to indomethacin and some are rapidly up-regulated after cryogenic burns. A role in promoting cell migration is strongly suggested. Knockout mice lacking TFF1 or TFF3 show significant pathology, with the former developing gastric tumours. A recent Conference Philippe Laudat agreed upon a new nomenclature for these peptides.

Animals↗
PubMed1997

Lung stem cells.

The identity of putative stem cells in tracheobronchial, bronchiolar and alveolar compartments is reviewed. Their developmental appearance is described, as is the experimental evidence for their ability to repopulate areas of damage caused by noxious agents such as ozone, mineral fibres, chemicals and mechanical or enzymatic removal. Factors affecting pulmonary cell proliferation and differentiation are considered. The role played by these cells in carcinogenesis is also discussed, with consideration of the position of neuroendocrine cells in this process.

Adult↗
PubMed1996

Effects of pancreatic spasmolytic Polypeptide (PSP) on epithelial cell function.

Trefoil peptides are expressed near endodermal ulcerations and may modulate epithelial repair. The trefoil pancreatic spasmolytic polypeptide (PSP) was tested for growth activity in vitro on epithelial cells and in vivo following intragastric or intravenous infusion in parenterally fed intact rats. Ion transport was assessed as changes in short-circuit current in rat intestine and adenocarcinoma cells in Ussing chambers. PSP stimulated growth of MCF-7 and Colo-357 cells, but only in the presence of extracellular glutathione (GSH). The effect was attenuated by GSH depletion with buthionine sulphoximine, even in GSH-containing media. When GSH-reduced PSP was carboxymethylated with iodoacetic acid, it still depended on extracellular GSH for its growth effect. Intestinal epithelial proliferation in rats was not affected by either intravenous or intraluminal infusion. PSP had no effect on basal or stimulated ion flux in rat jejunum or epithelial monolayers. The peptide did not compete with 125I-labeled epidermal growth factor for its receptor. [14C]Iodoacetamide treatment of PSP, followed by prolonged tryptic digestion yielded predominantly a 14C-labeled tetrapeptide fragment containing Cys1O4, with a lesser quantity of a 14C-labeled 15-amino-acid peptide containing Cys95 (molar ratio 15:1). GSH may predominantly reduce the Cys6-Cys1O4 terminal disulphide bond in PSP. We conclude that some epithelia may exhibit a growth response to PSP if extracellular GSH is present. Reduction of PSP by GSH is not necessary for this response, suggesting that the trefoil receptor or its signal transduction is GSH sensitive. PSP could assist wound healing by interactions with epithelial cells exposed concurrently to a local high GSH concentration.

Animals↗
PubMed1995

Toxicity testing of wound dressing materials in vitro.

There is a bewildering array of dressing materials available for wound coverage. The choice of dressing is often by local custom or practical experience. We wished to investigate if different dressings varied in their ability to either stimulate or inhibit proliferative activity and differentiation in an in vitro test system. We have used a number of test systems for this study. Human dermal fibroblast and keratinocyte cultures were used to screen for proliferative and cytotoxic effects. A more complex "organotypic" method involving fibroblast-impregnated collagen gels overlaid with epidermal keratinocytes was used to investigate effects on differentiation. Dressings were selected from each of the major types available, from simple gauze to hydrocolloids. Of the dressings tested, some reduced cell growth rates but the majority showed no major effect on proliferation or differentiation. Of those displaying an effect, only one could be attributed to cytotoxicity.

3T3 Cells↗
PubMed1995

Cytotoxicity of wound dressing materials assessed using cultured skin equivalents.

An in vitro system, based on the Bell model of cultured composite skin equivalents, was used to assess the effect of a number of wound dressing materials on DNA synthesis. DNA synthesis was quantified using immunocytohistochemical identification of incorporated bromodeoxy-uridine and the percentage of labelled cells measured, following 7 days' exposure to the dressing material. Differences in labelling index were observed from replica gels covered by different dressing materials and between dressings of the same type of material, but made by different manufacturers.

Animals↗
PubMed1995

Survival of allogeneic cells in cultured organotypic skin grafts.

Organotypic cultures of human skin were made using dermal fibroblasts seeded into a type I collagen gel overlaid with epidermal keratinocytes. Full-thickness excision of tattoos was performed on five patients, three of whom received sex-mismatched allografts. Patients were not immunosuppressed. Biopsies were obtained up to 3.5 years later. In situ hybridization of the PHY2.1 repetitive Y chromosome sequence revealed male fibroblasts and keratinocytes at 11 weeks and 2.5 years in the two female patients grafted with male cells. Structural components in the dermal substitute matured with time, and elastic fibers formed an interlacing meshwork by 18 months. Electron microscopy of the dermal-epidermal junction of an organotypic allograft revealed anchoring fibrils that had normal features at this time. Hyperemia of early grafts settled and contour correction was maintained, while repigmentation was variable. Hypertrophic scars did not occur, and graft contracture was never more than 20 percent. We conclude that this organotypic skin graft shows potential toward the goal of allogeneic skin replacement in a one-step procedure.

Adult↗
PubMed1994

[Texture analysis: a new method for evaluating ultrasound imaged lesions of the breast].

Echogenicity and echostructure in sonomammography are essential criteria to determine the malignancy of a breast tumor. Looking for a correlation between echostructure of an ultrasound image and its histopathology a texture analysis was performed. Ultrasonic examinations were carried out by means of a 7.5-MHz linear scanner under standardized conditions. 71 mammasonographic findings were documented by video tape, each tumor in 2 dimensions. In a second step 'the region of interest', that means the whole tumor area, was marked and statistically analyzed by a dedicated computer system. The values of 23 first- and second-order statistical texture parameters were compared with the histopathology of the tumor. They include grey level histogram, Fourier analysis and cooccurrence matrix. The most important results were obtained in the histogram analysis. An obvious distinction could be worked out concerning carcinomas, adenomas, mastopathic tumors, and fat necrosis. Except the difference between carcinomas and adenomas this distinction was statistically significant. Fourier analysis and coocurrence matrix significantly separate fibrocystic lesions, fat necrosis, scars, and cystic structures from malignant tumors. Furthermore the maximum value method was used to compare the different parameters with regard to their capability of discriminating benign and malignant tumors. The extreme values of 100% were mostly observed in the case of seromas and scars. A significant difference was found by histological grading of carcinomas, too. Highly differenciated carcinomas show capability of results comparable to those of adenomas. By means of a computer texture analysis program it is possible to find a correlation between echostructure and histopathology of breast tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1992

Fluorimetric DNA assay for cell growth estimation.

A growth assay using the fluorescent dye Hoechst 33258 has been developed which allows sensitive and rapid analysis of the DNA content of a variety of cell types including keratinocytes and mucus-secreting cells, and which requires a minimum of liquid handling. The assay can detect as few as 500 diploid human cells, and is compatible with the simultaneous detection of [3H]thymidine incorporation in the same cultures.

Animals↗
PubMed1990

Dermal equivalents.

Explore the source record for details and available documents.

Artificial Organs↗
PubMed1989

Cultured composite skin grafts: biological skin equivalents permitting massive expansion.

After assessment in mice, a biological skin equivalent consisting of cultured fibroblasts in a collagen gel overlain with cultured keratinocytes was applied to three patients who had had tattoos excised. In all patients the grafts took well with good cosmetic results and little or no contracture. A biopsy at 4 weeks showed that the central graft area had a fully differentiated epidermis and a mature dermis without adnexae.

Adult↗
PubMed1989

12-Hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) does not stimulate proliferation of human neonatal keratinocytes.

We have developed an assay to study the effect of drugs on the proliferation of neonatal human skin-derived keratinocytes in vitro. Expanding populations of neonatal keratinocytes were cultured in low concentrations (0.5%) of fetal calf serum for up to 12 d. Growth of the cultures was determined by measurement of DNA using a sensitive fluorimetric assay. Addition of 10(-9)-10(-6) M 12(RS)-hydroxy-5,8,10,14-eicosatetraenoic acid (12(RS)-HETE) neither stimulated keratinocyte proliferation nor enhanced the incorporation of [3H]thymidine. The ability of neonatal keratinocytes in low serum medium to respond to exogenous factors was demonstrated by increased growth in response to a mixture of cholera toxin, hydrocortisone, and epidermal growth factor. Confluent keratinocyte cultures in 10% human AB serum exposed to 12(S)-HETE for 72 h also showed no changes in DNA, [3H]thymidine incorporation, or labeling index. Metabolism of 12(S)-[3H]HETE was greater in cultures containing low concentrations of serum but there was no evidence for the formation of 12,20-dihydroxyeicosatetraenoic acid.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1979

The relationship between protein turnover and energy balance in lean and genetically obese (ob/ob) mice.

1. Groups of lean and genetically obese (ob/ob) mice were adapted to varying energy intakes and the rates of total protein turnover in liver, gut and kidney were measured. 2. Lean mice gained less weight when fed above maintenance and lost less weight when fed below maintance than obese mice. 3. Hepatic protein turnover (mg/d) was sigmoidally related to digestible energy intake in lean mice but showed no significant changes with dietary intake in obese mice. 4. The changes in protein turnover resulted from changes in both the half-lives of protein synthesis and catabolism and in tissue protein content. 5. In the lean mice, protein turnover in kidney and gut was not significantly changed with increasing energy intake until the highest level was reached. 6. The findings suggest that protein turnover may be an important cycle for the regulation of energy balance in mice and that this cycle is impaired in the genetically obese (ob/ob) mice.

Animals↗