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Biomedical subjects

M Simon

Publications and source records attributed to M Simon.

At least 289 records · Page 16Linked to original sources
PubMed1993

Characterization of retinol metabolism in cultured human epidermal keratinocytes.

Retinoids present in cultured human epidermal keratinocytes maintained in medium containing 25 nM retinol were identified and quantitated utilizing reverse-phase gradient high performance liquid chromatography. Total cell retinoid mass and composition averaged 12.59 pmol/mg cell protein +/- 1.86, (mean +/- S.D., n = 5) between strains and was constant with culture age. Long chain fatty acid esters of retinol and 3,4-didehydroretinol comprised greater than 95% of total retinoid, each contributing 77 and 23% of total esters, respectively. In mature stratified cultures, less abundant retinoids included unesterified retinol, 1%, and 3,4-didehydroretinol, 0.5%, retinoic acid, 0.5%, and a retinoid not previously reported in mammalian cells, 3,4-didehydroretinoic acid, 0.3%. This absolute and relative retinoid composition was essentially constant with culture age except that 3,4-didehydroretinoic acid was not detected in 3-4-day-old cultures (16-32 cell colonies), suggesting that keratinocyte differentiation may be related to endogenous changes in production of "active" retinoids. Separate pools of retinyl and 3,4-didehydroretinyl esters served as predominant sources of substrate for production of retinoic and 3,4-didehydroretinoic acids, respectively, suggesting that their production may be regulated independently.

Adult↗
PubMed1993

A polypeptide bound by the chaperonin groEL is localized within a central cavity.

Chaperonins are oligomeric protein complexes that play an essential role in the cell, mediating ATP-dependent polypeptide chain folding in a variety of cellular compartments. They appear to bind early folding intermediates, preventing their aggregation; in the presence of MgATP and a cochaperonin, bound polypeptides are released in a stepwise manner, associated with folding to the native state. Chaperonin complexes appear in the electron microscope as cylindrical structures, usually composed of two stacked rings, each containing, by negative staining, an electron dense central "hole" approximately 6.0 nm in diameter. We sought to identify the site on the Escherichia coli chaperonin groEL, where the "molten globule"-like intermediate of dihydrofolate reductase (DHFR) becomes bound, by examining in the scanning transmission electron microscope complexes formed between groEL and DHFR molecules bearing covalently crosslinked 1.4-nm gold clusters. In top views of the groEL complexes, gold densities were observed in the central region; in side views, the densities were seen at the end portions of the cylinders, corresponding to positions within the individual rings. In some cases, two gold densities were observed in the same groEL complex. We conclude that folding intermediates are bound inside central cavities within individual chaperonin rings. In this potentially sequestered location, folding intermediates with a compact conformation can be bound at multiple sites by surrounding monomeric members of the ring; localization of folding within the cavity could also facilitate rebinding of structures that initially fail to incorporate properly into the folding protein.

Bacterial Proteins↗
PubMed1993

Human breast cancer: frequent p53 allele loss and protein overexpression.

A sample of 114 primary breast tumors and corresponding constitutional DNA were tested for loss of heterozygosity (LOH) of the YNZ22 and p53 genes, both located in the 17p13 region. Loss of the p53 allele was found in 28 of 44 primary breast carcinomas (64%). In contrast LOH in only 26 of 61 tumors (43%) was detected with the variable number of tandem repeats (VNTR) probe YNZ22 mapping at 17p13.3 close to the p53 locus at 17p13.1. Among 19 tumors informative for both probes allele loss at 17p13.3 never occurred without p53 involvement. These data suggest, that p53 is the target of 17p13 allelic deletions in human breast cancer. Immunohistochemistry showed overexpression of the p53 protein in 25 of 50 cases (50%) presumably reflecting activating point mutations. Overexpression was not correlated with allele loss but seemed to be closely related to the presence of point mutations in this study. No homozygous deletions or rearrangements of the p53 gene were detected. This would argue for an important role of heterozygous p53 mutations in human breast cancer.

Alleles↗
PubMed1993

Pharmacokinetics of vancomycin during continuous hemodiafiltration.

OBJECTIVE: To study the pharmacokinetics of vancomycin in three patients with acute renal failure related to multi-organ failure during continuous venovenous hemodiafiltration (CVVHD). DESIGN: Prospective exploratory, open-labelled study. SETTING: Critical Care Unit in a University Medical Centre. PATIENTS: 3 patients exhibiting hemodynamic instability and oligo-anuric acute renal failure requiring extra-renal epuration were included in this study. INTERVENTION: Every patient received 7.5 mg/kg IV vancomycin over 1 h for a documented or suspected nosocomial staphylococcal infection. Serum and dialysate outlets samples were collected before infusion and 1, 3, 6, 12, 18, 24 after the end of infusion. MEASUREMENTS AND RESULTS: Mean age was 58.7 years (range 41-79) and mean SAPS 15.7 (9-23). The mean peak concentrations were 27.3 mg/l (range 15.6-45.6) one hour after the end of infusion. The average remaining vancomycin concentration 24 h after the onset of infusion was 3.6 mg/l (range 2.6-4.5). The mean terminal disposition rate constant and elimination half-life were 0.05 h-1 and 13.9 h respectively. Mean total body clearance was 38.9 +/- 4.3 ml/min and dialysate outlet (DO) clearance 4.2 +/- 1.3 ml/min. The mean volume of distribution was 47.4 +/- 6.4 l. CONCLUSION: CVVHD is effective for vancomycin elimination. In these patients, the elimination half-life is almost constant, involving a following injection of vancomycin 12 h later to achieve effective concentrations.

Acute Kidney Injury↗
PubMed1993

Organochlorines, including chlordane compounds and their metabolites, in peregrine-falcon, prairie-falcon, and clapper-rail eggs from the USA.

Four compounds present in technical chlordane (trans- and cis-nonachlor, and tentatively MC-2 and MC-5) and three metabolites of chlordane (heptachlor epoxide, oxychlordane, and U-4) were identified by GC/MS in peregrine-falcon (Falco peregrinus anatum) eggs. Levels of Heptachlor epoxide, oxychlordane, trans- and cis-chlordane, trans- and cis-nonachlor, MC-2, and MC-5 were quantified by GC/ECD in peregrine-falcon eggs from the US east coast, Colorado, and California; and in prairie-falcon (Falco mexicanus) and light-footed-clapper-rail (Rallus longirostris levipes) eggs from California. The eggs were collected between 1986 and 1989. Oxychlordane, heptachlor epoxide, trans- and cis-nonachlor, MC-2, and MC-5 were detected in every egg analyzed. Heptachlor, trans-, and cis-chlordane were either not detected, or present at low levels in the eggs. The highest Sigmachlordane levels were found in the East Coast peregrine-falcon eggs at a geometric mean (geom. mean) concentrations of 1800 microg/kg (ppb); the lowest levels of Sigmachlordane were found in the prairie-falcon eggs at a concentration of 120 microg/kg (geom. mean). Of the technical chlordane compounds measured, MC-2 bioaccumulated to the greatest degree. SigmaDDT levels in the falcons ranged from 11 000 microg/kg (geom. mean) in the Colorado samples to 8800 microg/kg (geom. mean) in the East Coast and California peregrines. SigmaDDT levels in the rail eggs were 3000 microg/kg (geom. mean). The highest SigmaPCB levels were found in the East Coast peregrine-falcon eggs at a concentration of 14 000 microg/kg (geom. mean); the lowest levels of SigmaPCB were found in the prairie-falcon eggs at a concentration of 350 microg/kg (geom. mean).

Journal Article↗
PubMed1993

Forequarter amputation wound coverage with an ipsilateral, lymphedematous, circumferential forearm fasciocutaneous free flap in patients undergoing palliative shoulder-girdle tumor resection.

Closure of massive soft-tissue defects in patients undergoing forequarter amputation for shoulder-girdle tumors may present a daunting challenge. This report describes two patients whose forequarter amputations were closed using ipsilateral, lymphedematous, circumferential forearm fasciocutaneous free flaps.

Aged↗
PubMed1993

[15N-labeling of fishes using 15N isotopes in aquarium water and the effect of a different protein nutrient on the 15N elimination after the labeling period].

In a preexperiment of 12 days fishes (Cyprinus carpio L.) were labelled with 15N by means of 15NH4Cl and 15N-urea resp. in the aquarium water and by feeding a protein free diet. 15NH4Cl yielded a higher atom-% 15N excess (15N') in the tissues of fishes. In the main experiment 75 fishes (Cyprinus carpio L.) were 15N-labelled with 100 mg 15N'/l water from 15NH4Cl (95 atom-% 15N') in a protein free preperiod of 12 days. In the following main period the fishes received different protein sources in their diets in maintenance. A group of 20 fishes received an animal protein (fish meal) and two groups of 20 fishes each received plant proteins (soybean meal and wheat gluten resp.). The atom-% 15N' reached after the 15N-labelling period following values: digestive tract with content--7.15, liver--5.65, gills--5.89, muscle--0.81 and chorda dorsalis--1.09 respectively. During the main period (with protein feeding) the atom-% 15N' decreased in the tissues with high protein turnover (liver and gills) on the 2nd and 4th day to 4.31 +/- 0.11 (animal protein) and 4.64 +/- 0.14 (plant proteins) in average. The corresponding values in the tissues with low protein turnover (muscle and chorda dorsalis) were 0.73 +/- 0.04 and 0.80 +/- 0.04 atom-% 15N' in average. From the measurements on the 6th, 8th and 10th day of protein feeding resulted an atom-% 15N' in average of liver and gills of 4.08 +/- 0.13 (animal protein) and 4.11 +/- 0.15 (plant proteins). In muscle and chorda dorsalis the atom-% 15N' ascended in this time upon 0.80 +/- 0.04 (animal protein) and 0.90 +/- 0.03 (plant proteins). It seems that the protein metabolism of fishes is favoured from the amino acid of plant protein in comparison to animal protein to reduce the 15N-loss of the 15N-labelled body in maintenance, like the results from experiments with rats (Hernandez et al., 1981).

Animal Feed↗
PubMed1993

The involucrin genes of the mouse and the rat: study of their shared repeats.

The involucrin genes of the mouse (Mus musculus) and the rat (Rattus norvegicus) have been cloned and sequenced. The coding region of each gene contains, at site P, a segment of repeats homologous to that of other nonanthropoid mammals. In contrast to the repeats of species belonging to different mammalian orders, many individual repeats of the mouse and the rat can be matched. Both before and after the divergence of the two species, these repeats have been the site of systematic alterations in nucleotide sequence. One of the alterations is the correction of nucleotides of one repeat by those of another. Corrected nucleotides may be closely linked to flanking nucleotides that are uncorrected; the systematic correction process therefore appears to be due to gene conversion. There is a stretch of 18 reiterated CAGs in the segment of repeats of the Mus gene; most of these reiterations were introduced recently, supporting the idea that the gene was generated originally from poly CAG. An antiserum to a synthetic peptide encoded by the segment of repeats of the Mus gene reveals differentiation-specific expression of the gene in the epidermis.

Animals↗
PubMed1993

Expression of monocyte/macrophage markers (CD13, CD14, CD68) on human keratinocytes in healthy and diseased skin.

The results of several investigations proved that, in special circumstances, human keratinocytes (HKs) synthesize and express cell surface moieties characteristic of effector and/or accessory cells of the immune system, such as CD16, CD36, HLA-DR, and intercellular adhesion molecule-1 (CD54), which are all detectable on the surfaces of macrophages. In the present study, skin biopsies from healthy volunteers, from positive tuberculin skin tests, and from patients with acute urticaria (AU), lichen planus (LP), psoriasis vulgaris (PV), mycosis fungoides (MF), and purpura pigmentosa chronica (PPC) were investigated by means of a multistep immunoperoxidase method to examine the reactivity of the HKs with a panel of monoclonal antibodies (MABs) characteristic of monocyte/macrophage cell lines. In biopsies obtained from positive tuberculin tests and from clinically involved skin of patients with LP, PV, MF, or PPC, a multifocal, positive peroxidase reaction was observed on the membranes of HKs of the basal and suprabasal cell layers when the MABs OKM13 (CD13), OKM14 (CD14), and Dako-Macrophage (CD68) were used. In contrast, specific staining of the HKs was not observed with the same antibodies in the biopsies of healthy volunteers or of patients with AU or in the uninvolved skin specimens obtained from the other patients. The HKs of PV, LP, MF, PPC, and AU patients and those of the healthy subjects all failed to give positive reactions when MABs against CD11b, CD15, or CD33 were used. The published data supplement the known surface characteristics of HKs, reflecting their stage of activation and differentiation.

Antigens, CD↗
PubMed1993

Macrophage markers 25F9 and 27E10 on human keratinocytes in normal and diseased skin.

In the present study, an immunohistochemical analysis was made of the expression pattern of different macrophage markers such as 25F9, 27E10 and RM 3/1 on the surface of human keratinocytes (HK) in biopsies obtained from healthy volunteers and from patients with lichen planus, chronic cutaneous graft-versus-host reaction, mycosis fungoides, and purpura pigmentosa chronica. In biopsies from the healthy volunteers and from both clinically involved and uninvolved skin of the patients, the HK of the basal cell layer exhibited a specific peroxidase-positive reaction when the monoclonal antibody against 25F9 was used. Lesional HK from all patients studied displayed 25F9 and 27E10 in nearly the entire epidermis. The present findings provide further evidence that HK and macrophages share a number of common cell surface moieties.

Antigens, Surface↗
PubMed1993

Characterisation of the rat oesophagus epithelium antigens defined by the so-called 'antikeratin antibodies', specific for rheumatoid arthritis.

OBJECTIVES: An attempt was made to characterise the antigens recognised by serum IgG antibodies directed to the stratum corneum of rat oesophagus epithelium, the so-called 'antikeratin antibodies', which were shown to be highly specific for rheumatoid arthritis (RA) and thus to have an actual diagnostic value. METHODS: Immunoblotting was performed with RA serum samples on different extracts of rat oesophagus epithelium separated by various monodimensional and two dimensional electrophoreses. RESULTS: Three low-salt-soluble antigens sensitive to proteinase K and, therefore, of protein nature were identified. Two proteins, with apparent molecular masses of 210 and 120-90 kilodaltons, shared isoelectric points ranging from 5.8 to 8.5; the third protein exhibited isoelectric points from 4.5 to 7.2 while its molecular mass ranged from 130 to 60 kilodaltons. Immunoadsorption of RA serum samples onto cytokeratins extracted from the stratum corneum of rat oesophagus epithelium did not change their immunoreactivity towards the three antigenic proteins. Widely used deglycosylation and dephosphorylation methods failed to modify either the electrophoretic migration of the proteins or their immunoreactivity with RA serum samples. CONCLUSION: The so-called 'antikeratin antibodies' do not react with cytokeratins. They specifically recognise three late epithelial differentiation proteins which had not been previously described. These proteins may be related to (pro)filaggrin.

Animals↗
PubMed1993

Comparative evaluation of clinically available inferior vena cava filters with an in vitro physiologic simulation of the vena cava.

PURPOSE: A physiologic in vitro model of the human inferior vena cava (IVC) was developed to evaluate the clot-trapping efficiency of various IVC filters. MATERIALS AND METHODS: The flow model closely simulates the physical parameters of the human IVC in fluid viscosity, specific gravity, temperature, and pulsatility; blood flow velocity, volume, and inherent turbulence; and vein orientation, wall compliance, and clot composition. Five filters--Greenfield (G), Bird's Nest (BN), Vena Tech (VT), Simon nitinol (SN), and titanium Greenfield (TG)--were compared by using two vena cava and blood clot sizes and horizontal and vertical orientation of the model. RESULTS: Each filter varied significantly in its clot-capturing efficiency, depending on vena cava size and orientation and emboli size. Overall, decreasing rank order in filter clot-trapping efficiency was SN, BN, VT, TG, and G. CONCLUSION: The in vitro model of the human IVC is an alternative to multicenter clinical trials in evaluating the relative clot-trapping efficiency of various IVC filters.

Equipment Design↗
PubMed1993

Comparative plasma disposition and anticoagulant activities of racemic phenprocoumon and its metabolites in rats.

The anticoagulant phenprocoumon (PH) and its metabolites 6-hydroxy-, 7-hydroxy- and 4'hydroxy-phenprocoumon (6-OH-PH, 7-OH-PH and 4'-OH-PH, respectively) were separately administered intravenously as racemates to rats in order to measure the potential effects of the major metabolites of PH on coagulation. Plasma samples were assayed for total concentrations of the administered compounds and the corresponding prothrombin times; kinetic parameters and anticoagulant activities were estimated using a pharmacodynamic model based on the rate of synthesis of clotting factors. The relative potencies were in the order PH > 4'-OH-PH > 6-OH-PH > 7-OH-PH the latter showing no activity. Patients on PH therapy showed lower plasma concentrations of metabolites than of PH; in humans the metabolites of PH will not contribute significantly to the overall anticoagulant activity of the drug.

Animals↗
PubMed1993

Progressive partially symmetric erythrokeratodermia with deafness: histological and ultrastructural evidence for a subtype distinct from Schnyder's syndrome.

An atypical case of the rare genodermatosis erythrokeratodermia progressiva partim symmetrica (EPPS) with deafness and myopathy is described. Our findings suggest that this case of EPPS with deafness and myopathy represents a distinct entity of atypical erythrokeratodermias with characteristic epidermal and dermal skin changes.

Adult↗
PubMed1993

The cytokeratin filament-aggregating protein filaggrin is the target of the so-called "antikeratin antibodies," autoantibodies specific for rheumatoid arthritis.

In rheumatoid arthritis (RA), the high diagnostic value of serum antibodies to the stratum corneum of rat esophagus epithelium has been widely reported. These so-called "antikeratin antibodies," detected by indirect immunofluorescence, were found to be autoantibodies since they also labeled human epidermis. Despite their name, the actual target of these autoantibodies was not known. In this study, a 40-kD protein (designated as 40K), extracted from human epidermis and specifically immunodetected by 75% of RA sera, was purified and identified as a neutral/acidic isoform of basic filaggrin, a cytokeratin filament-aggregating protein, by peptide mapping studies and by the following evidences: (a) mAbs specific for filaggrin reacted with the 40K protein; (b) the autoantibodies, affinity-purified from RA sera on the 40K protein, immunodetected purified filaggrin; (c) the reactivity of RA sera to the 40K protein was abolished after immunoadsorption with purified filaggrin; (d) the 40K protein and filaggrin had similar amino acid compositions. Furthermore, autoantibodies against the 40K protein and the so-called "antikeratin antibodies" were shown, by immunoadsorption experiments, to be largely the same. The identification of filaggrin as a RA-specific autoantigen could contribute to the understanding of the pathogenesis of this disease and, ultimately, to the development of methods for preventing the autoimmune response.

Amino Acids↗
PubMed1993

Prognostic factors in Waldenström's macroglobulinemia: a report of 167 cases.

PURPOSE: A single-center retrospective analysis was conducted in 167 patients with Waldenström's macroglobulinemia (WM) to delineate prognostic factors. PATIENTS AND METHODS: One hundred sixty-seven patients diagnosed between January 1969 and December 1988, fulfilling diagnostic criteria of WM, were entered onto this study. One hundred twenty-eight patients were treated with chlorambucil (0.1 mg/kg/d): 117 at diagnosis and 11 during the disease course. Seventeen variables were analyzed in all patients and in treated patients for their prognostic value on survival using the Kaplan-Meier method and a Cox multivariate regression analysis. RESULTS: Median survival duration for all patients was 60 months. Pretreatment factors associated with shorter survival in the entire population were age > or = 60 years (P = .006), male sex (P = .0001), general symptoms (P = .01), hemoglobin less than 10 g/dL (P = .008), leukocytes less than 4 X 10(9)/L (P = .02), neutrophils less than 1.7 X 10(9)/L (P = .02), and platelets less than 150 X 10(9)/L (P = .0006). Organomegaly, signs of hyperviscosity, renal failure, monoclonal immunoglobulin M (M IgM) level, blood lymphocytosis, and percentage of marrow lymphoid cells were not significantly correlated with survival. In a Cox multivariate regression analysis, the combination of factors that gave the best prognostic value was the association of sex (P = .0002), neutrophils (P = .002), age (P = .008), and hemoglobin (P = .02). CONCLUSION: Our findings suggest that some pretreatment parameters, including older age, male sex, general symptoms, and cytopenias, carry a poor prognosis in WM. By contrast, high initial tumor burden (indicated by organomegaly, high IgM level, and high percentage of marrow lymphoid cells) does not seem to be significantly associated with short survival. Our results help define a high-risk population that could perhaps benefit from newer therapeutic approaches.

Aged↗