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Biomedical subjects

A Stiefel

Publications and source records attributed to A Stiefel.

At least 19 recordsLinked to original sources
PubMed2005

Microhardness changes in dentine after neonatal capsaicin application.

AIM: To determine if desensitization of the nociceptive innervation in the dental pulp has an effect on odontoblast function in the rat. METHODOLOGY: Neonatal systemic application of capsaicin was used to selectively eliminate nociceptive innervation. 12 capsaicin-treated rats were intravitally perfused at 150 days of life with 4% formaldehyde and jaws were prepared for Vicker's microhardness (VMH) measurement. As a control, 12 rats were injected with vehicle on the 3rd day of life and intravital perfusion was carried out exactly as those used for the experimental group. Immunohistological labeling of CGRP was carried out in both groups to assure the efficiency of desensitization in the experimental group. The VMH was measured in the incisors of each animal for a quantitative analysis of dentine quality. RESULTS: Vicker's microhardness was significantly higher in the control rats compared with the capsaicin-treated rats (P < 0.001). CONCLUSIONS: Neonatal systemic application of capsaicin produces changes in the quality of dentine in the rat over time and therefore it is suggestive that selective elimination of the nociceptive innervation in pulpal tissue may effect odontoblast function.

Analgesics, Non-Narcotic↗
PubMed2001

Control of the ferric citrate transport system of Escherichia coli: mutations in region 2.1 of the FecI extracytoplasmic-function sigma factor suppress mutations in the FecR transmembrane regulatory protein.

Transcription of the ferric citrate transport genes is initiated by binding of ferric citrate to the FecA protein in the outer membrane of Escherichia coli K-12. Bound ferric citrate does not have to be transported but initiates a signal that is transmitted by FecA across the outer membrane and by FecR across the cytoplasmic membrane into the cytoplasm, where the FecI extracytoplasmic-function (ECF) sigma factor becomes active. In this study, we isolated transcription initiation-negative missense mutants in the cytoplasmic region of FecR that were located at four sites, L13Q, W19R, W39R, and W50R, which are highly conserved in FecR-like open reading frames of the Pseudomonas aeruginosa, Pseudomonas putida, Bordetella pertussis, Bordetella bronchiseptica, and Caulobacter crescentus genomes. The cytoplasmic portion of the FecR mutant proteins, FecR(1-85), did not interact with wild-type FecI, in contrast to wild-type FecR(1-85), which induced FecI-mediated fecB transport gene transcription. Two missense mutations in region 2.1 of FecI, S15A and H20E, partially restored induction of ferric citrate transport gene induction of the fecR mutants by ferric citrate. Region 2.1 of sigma(70) is thought to bind RNA polymerase core enzyme; the residual activity of mutated FecI in the absence of FecR, however, was not higher than that of wild-type FecI. In addition, missense mutations in the fecI promoter region resulted in a twofold increased transcription in fecR wild-type cells and a partial restoration of fec transport gene transcription in the fecR mutants. The mutations reduced binding of the Fe(2+) Fur repressor and as a consequence enhanced fecI transcription. The data reveal properties of the FecI ECF factor distinct from those of sigma(70) and further support the novel transcription initiation model in which the cytoplasmic portion of FecR is important for FecI activity.

Amino Acid Sequence↗
PubMed1997

Transcription induction of the ferric citrate transport genes via the N-terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane.

Ferric citrate induces transcription of the ferric citrate transport genes fecABCDE without entering the cells of Escherichia coli K-12. Point mutants of the outer membrane-receptor protein FecA are affected in induction independent of the FecA transport activity, suggesting that FecA is directly involved in induction. Alignment of FecA with the other ferric siderophore receptors of E. coli reveals an N-terminal extension in FecA that is not found in the receptors whose synthesis is not induced by their cognate ferric siderophores. In this study, we show that excision of the N-terminal region abolished the inducing activity of FecA, but retained its transport activity. Overproduction of the N-terminal FecA fragment inhibited FecA-dependent induction, but not transport. Constitutive expression caused by C-terminally truncated FecR derivatives was not inhibited by the N-terminal FecA fragment. The N-terminal region of FecA was localized in the periplasm, which indicates that FecA probably interacts with FecR, which is involved in signal transduction across the cytoplasmic membrane. Transcription initiation of the fec transport genes required the Ton system, consisting of TonB, ExbB, and ExbD, and was inhibited by carbonylcyanide-m-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP), which dissipate the electrochemical potential of the cytoplasmic membrane. fec transcription of mutant fecA4, which displays constitutive fec transcription in the absence of TonB, was not affected by CCCP. The data support a model that proposes initiation of fec transport gene transcription by binding of ferric citrate to FecA. The transcription initiation signal is transferred across the outer membrane through the activity of the Ton system at the expense of the electrochemical potential of the cytoplasmic membrane. The N-terminus of FecA interacts in the periplasm with the C-terminus of FecR, through which the signal is transferred across the cytoplasmic membrane into the cytoplasm, where it increases the activity of the sigma factor Fecl, which then directs the RNA polymerase to the fec promoter upstream of fecA.

Amino Acid Sequence↗
PubMed1991

[Maturation of enamel and tooth eruption].

The tertiary maturation of the erupting tooth needs much more time than it is supposed in literature. Possibly the completion is in accord with the decline of the caries activity at the end of the second decade of lifetime. With the aid of polarizing microscopy, electron microprobe, microhardness testing (Vickers) and scanning electron microscopy different stages of posteruptive maturation from human and other mammalian teeth were analysed. The mineralization level in the outer surface of human enamel is completing little by little in more than 5 years after eruption. This state is in the ruminant tooth obvious never within reach in consequence of the specific physiological conditions. The maturating mineralization after our preliminary findings is fundamentally different to remineralization.

Animals↗
PubMed1991

[Electron probe microanalysis of fluorine content in deciduous and permanent teeth from an area with a fluoride-deficient (0,3% mg/I) water supply].

The content of fluorine in deciduous and permanent teeth of young people was determined by x-ray microanalysis. The purpose of this investigation was to determine the concentrations of F in teeth without any supplementation of fluorides and to elaborate basic dates as a standard of comparison. F was measured in microvolumes with a wavelength-dispersive spectrometer (Step-Scan 100 sec) after coating with about 300 A of Carbon. The highest values were established in the outermost surface of enamel with quantities between 300 and 600 micrograms/g. The lower concentrations were found in deciduouns teeth. In both dentitions the F-content increases at the surface following the permanent change between de- and remineralization. In subsurface areas the values are decreasing quickly. At a deep of 10 microns from surface layer the content is only 70 micrograms/g and than it declines to a minimum of 20-30 micrograms/g.

Child↗
PubMed1988

[Non-Hodgkin's lymphoma of low-grade malignancy, to some extent mimicking glomus tumors].

Reddish-blue nodules were found on the tips of some of the toes of a 62-year-old woman. These nodules were painful when pressure was applied The clinical appearance of the efflorescence was most similar to that of glomangiomas. In addition, a lesion was observed on her lip that was suspected of being a lymphoma. The histological and immunohistological findings for all the lesions were consistent with the diagnosis of a non-Hodgkin lymphoma of low-grade malignancy. Consequently, a detailed internal medical examination was performed: biopsy specimens of the gastrointestinal mucosa revealed the presence of an immunocytoma. The significance of the immunohistological differentiation of lymphocyte subclasses by monoclonal antibodies for the diagnosis of lymphoma is demonstrated.

Diagnosis, Differential↗
PubMed1988

[Gingival hyperplasia and serous papules due to cyclosporin treatment].

After 3 months of immunosuppressive treatment with cyclosporin because of a focal segmental glomerulosclerosis, a 13-year-old female developed marked gingival hyperplasia, hypertrichosis of the arms and papulo-vesicular skin lesions on the left leg. Histological and immunohistological examinations of the gingivae showed hyperplasia of the mucosa with perivascular infiltrates of plasma and B cells in the submucosa. The lesions on the leg revealed signs of cutaneous vascular inflammation with eosinophils, but there was no evidence of leucocytoclastic vasculitis. Ten months after discontinuation of cyclosporin, the lesions had nearly regressed. The patient's renal function deteriorated progressively to the point of terminal insufficiency.

Adolescent↗
PubMed1987

[Juvenile linear IgA dermatosis].

In addition to hereditary epidermolysis, acquired chronic bullous diseases are also observed in childhood, juvenile linear IgA dermatosis being the most frequent. The case of a 6-year-old girl with the clinical, histological, electron microscopical and, especially, immunohistological findings typical for linear IgA dermatosis is reported. Successful therapy with oral sulfones is described.

Basement Membrane↗
PubMed1984

On the haemodynamic differences between sodium nitroprusside, nitroglycerin, and isosorbide nitrates. Comparison of their vasorelaxant effects in vitro and of their inactivation in vivo.

In organ bath studies, the sensitivity of isolated renal arteries and veins of the rabbit to sodium nitroprusside (SNP), nitroglycerin (GTN), and two isosorbide nitrates was compared. For isosorbide-dinitrate and isosorbide-5-mononitrate, a 7 to 20 times greater sensitivity of veins than of arteries was found explaining their known in vivo predilection for the capacitance vessels. To SNP and GTN, the immediate response was practically identical; a moderately greater sensitivity of the veins at threshold concentrations ( EC10 ), and a similar sensitivity of veins and arteries at the EC50 was observed with both drugs. However, on prolonged exposure (30 min), the relaxant response to GTN faded to a greater extent in arteries than in veins which may be a factor in the in vivo preference of GTN for the capacitance vessels. In anaesthetized rats, the hypotensive response to SNP and to GTN either infused i.v. or into the femoral artery, was compared. With GTN, the hypotensive response was the same by either route of administration. In contrast, the hypotensive response to SNP was considerably reduced on infusion into the femoral artery; an inactivation of SNP by 34% on passage through the hind-leg was calculated. The resulting decrease in venous over arterial blood levels of SNP could outweigh the somewhat greater sensitivity of veins than of arteries found in the organ bath, and may account for the balanced effect of SNP on resistance and capacitance vessels known to exist in vivo.

Animals↗
PubMed1983

In vivo and in vitro studies to elucidate the hemodynamic differences of sodium nitroprusside, nitroglycerin, and two isosorbide nitrates.

In isolated renal veins of the rabbit, isosorbide dinitrate and isosorbide-5-mononitrate were seven to twenty times more potent as relaxants than in renal arteries which explains their predilection for the capacitance vascular bed in vivo. For sodium nitroprusside (SNP) and nitroglycerin (NTG), the sensitivity was slightly greater in veins at threshold concentrations (EC10), but similar in veins and arteries at higher concentrations (EC50). After 30 min of exposure, the relaxant effect to NTG faded partially in arteries, but not in veins, which may underlie its preference for the capacitance vessels in vivo. In anaesthetized rats, SNP and NTG were infused i.v. or into the femoral artery. The hypotensive response to NTG was the same by either route of infusion, whereas that to SNP was considerably lower on infusion into the femoral artery; a 34% inactivation of SNP on passage through the hind leg was calculated. The result decrease in venous over arterial blood levels of SNP at a somewhat greater sensitivity of veins than of arteries may account for the balanced effect of SNP on resistance and capacitance vessels in vivo.

Animals↗
PubMed1979

[Peak-to-valley height measurement and scanning electron microscopy of cavity walls (author's transl)].

Using a feeler type of cutting mechanism and a scanning electron microscope, cavity walls were examined subsequent to the preparation thereof with various types of working tools. The combination of these two methods of examination allows results to be obtained which are far better than those achieved with the use of one of these methods alone. The most unfavourable configuration of the cavity wall is obtained using a turbine (diamond). It is especially in the case of inlay preparations that it is necessary for the walls of cavities prepared using a turbine to be retreated by means of a normal-speed type of instrument. Smoothest surfaces are generally obtained with the use of a finisher.

Dental Caries↗