Biomedical subjects

P Sommer

Publications and source records attributed to P Sommer.

At least 19 recordsLinked to original sources

PubMed2007

Heavy metal accumulation in trees growing on contaminated sites in Central Europe.

Metal-accumulating woody species have been considered for phytoextraction of metal-contaminated sites. We investigated Zn and Cd accumulation in tissues of adult trees and associated herbaceous species collected from contaminated areas in Central Europe. We found considerable Cd and Zn accumulation in various willow, poplar and birch species with up to 116mgCdkg(-1) and 4680mgZnkg(-1) in leaves of Salix caprea. Annual variation of Cd and Zn concentrations in leaves of Salix caprea were small, indicating that data obtained in different years can be compared. Metal concentrations in leaves were not related to total (aqua regia) or labile (1M NH(4)NO(3) extract) concentrations in soil but the accumulation factors (leaf concentration: soil concentration) for Cd and Zn followed an inverse log type function. Metal partitioning between tissues showed a minimum in the wood, with increasing concentrations of Cd and Zn towards the leaves and fine roots.

Biodegradation, Environmental↗

PubMed2006

[Collagen injection for augmentation of periprosthetic leakage after tracheo-esophageal voice restoration].

After laryngectomy the majority of patients receive a vocal rehabilitation by tracheo-esophageal puncture and insertion of voice prosthesis. Periprosthetic leakage causing aspiration represents a well known complication and is frequently treated by temporary removal of the prosthesis with shrinkage of the shunt. Here we describe 10 patients with such a leakage treated by collagen injection for periprosthetic tissue augmentation. A mean of 1,6 injections were necessary for complete control of the leakage. The injection was well tolerated and was found effective for median period of 9,3 months. In our hands the periprosthetic collagen injection represents an effective and well tolerated procedure for temporary augmentation of tracheo-esophageal leakage in post-laryngectomy patients. However, alternative fillers without pre-testing necessity and longer augmentation intervals should be considered.

Collagen↗

PubMed2005

Inhibition of lysyl oxidase activity can delay phenotypic modulation of chondrocytes in two-dimensional culture.

OBJECTIVE: Chondrocytes frequently de-differentiate in two-dimensional (2D) culture, especially in the presence of serum. To examine the role of lysyl oxidase (LOX) induced cross-linking in this phenomenon, the effect of the specific LOX inhibitor beta-aminopropionitrile (BAPN) was studied in 2D chondrocyte culture. DESIGN: Chick embryo sternal chondrocytes (both proliferative and hypertrophic, from caudal and cranial zones, respectively) were cultured in the presence and absence of BAPN. The production and activities of LOX and LOX-like (LOXL) were assessed by enzyme assay and the use of specific antibodies. Seventeen batches of serum of different origin were compared. Chondrocyte phenotype was assessed both morphologically and biochemically, the latter by quantitative analysis of production of radiolabeled cartilage collagens II, IX, X and XI, and the de-differentiation marker collagen I, for up to 4 weeks in culture. RESULTS: LOX and LOXL were identified, by Western blotting and immunofluorescence, and LO activity was measured in the medium, with both proliferative and hypertrophic chondrocytes. Inhibition of LO activity prevented or delayed chondrocyte de-differentiation, as characterized by changes in cell shape and synthesis of the five different collagen types, from the first days of culture for up to 4 weeks, depending on the origin of the serum added to the culture medium. CONCLUSION: LO activity may be involved in the control of chondrocyte phenotype, in addition to serum factors. Inhibition of LO activity by BAPN may be useful for the maintenance of the chondrocyte phenotype in 2D culture. Specific variations in the relative proportions of collagens II, IX and XI could be involved in the mechanism underlying these observations.

Aminopropionitrile↗

PubMed2005

Lysyl oxidase deficiency: a new cause of human arterial dissection.

Spontaneous coronary artery dissection is a rare cause of myocardial ischaemia. The underlying mechanism is unknown but some dissections are associated with extracellular matrix disorganisation of genetic origin. A deficiency in extracellular matrix protein cross links has rarely been studied. A single clinical case of spontaneous coronary artery dissection is reported. Lysyl oxidase (LOX) and extracellular matrix organisation were investigated by skin immunohistology and polymerase chain reaction of LOX expression. Both approaches found a dramatic LOX decrease. LOX deficiency has a major role in human arterial wall organisation during development. The suspected mechanism is an elastin or collagen polymer cross linking deficiency.

Adult↗

PubMed2004

Potential for using thermophilic anaerobic bacteria for bioethanol production from hemicellulose.

A limited number of bacteria, yeast and fungi can convert hemicellulose or its monomers (xylose, arabinose, mannose and galactose) into ethanol with a satisfactory yield and productivity. In the present study we tested a number of thermophilic enrichment cultures, and new isolates of thermophilic anaerobic bacterial strains growing optimally at 70-80 degrees C for their ethanol production from D-xylose. The new isolates came from different natural and man-made systems such as hot springs, paper pulp mills and brewery waste water. The test was composed of three different steps; (i) test for conversion of D-xylose into ethanol; (ii) test for viability and ethanol production in pretreated wheat straw hemicellulose hydrolysate; (iii) test for tolerance against high D-xylose concentrations. A total of 86 enrichment cultures and 58 pure cultures were tested and five candidates were selected which successfully fulfilled the criteria defined for the screening test.

Acetates↗

PubMed2004

Comparative genomics of two Leptospira interrogans serovars reveals novel insights into physiology and pathogenesis.

Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of Leptospira interrogans serovar Copenhageni and comparative analysis with the available Leptospira interrogans serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. Differences in genes involved in the biosynthesis of lipopolysaccharide O side chains between the Copenhageni and Lai serovars were identified, offering an important starting point for the elucidation of the organism's complex polysaccharide surface antigens. Differences in adhesins and in lipopolysaccharide might be associated with the adaptation of serovars Copenhageni and Lai to different animal hosts. Hundreds of genes encoding surface-exposed lipoproteins and transmembrane outer membrane proteins were identified as candidates for development of vaccines for the prevention of leptospirosis.

Animals↗

PubMed2003

Purification of bioethanol effluent in an UASB reactor system with simultaneous biogas formation.

In this study, the prospect of using an Upflow Anaerobic Sludge Blanket (UASB) reactor for detoxification of process water derived from bioethanol production has been investigated. The bioethanol effluent (BEE) originated from wet oxidized wheat straw fermented by Saccharomyces cerevisiae and Thermoanaerobacter mathranii A3M4 to produce ethanol from glucose and xylose, respectively. In batch experiments the methane potential of BEE was determined to 529 mL-CH(4)/g-VS. In batch degradation experiments it was shown that the presence of BEE had a positive influence on the removal of the inhibitors 2-furoic acid, 4-hydroxyacetophenone, and acetovanillone as compared to conversion of the inhibitors as sole substrate in synthetic media. Furthermore, experiments were carried out treating BEE in a laboratory-scale UASB reactor. The results showed a Chemical Oxygen Demand (COD) removal of 80% (w/w) at an organic loading rate of 29 g-COD/(L. d). GC analysis of the lignocellulosic related potentially inhibitory compounds 2-furoic acid, vanillic acid, homovanillic acid, acetovanillone, syringic acid, acetosyringone, syringol, 4-hydroxybenzoic acid, and 4-hydroxybenzaldehyde showed that all of these compounds were removed from the BEE in the reactor. Implementation of a UASB purification step was found to be a promising approach to detoxify process water from bioethanol production allowing for recirculation of the process water and reduced production costs.

Bacteria, Anaerobic↗

PubMed2001

A comparison of laparoscopic Toupet versus Nissen fundoplication in gastroesophageal reflux disease.

BACKGROUND AND AIMS: Laparoscopic Nissen fundoplication is used very frequently but may lead to postoperative bloating, inability to belch, and dysphagia. Partial wrapping has been reported to be equally effective but associated with fewer unfavorable postoperative symptoms. The aim of this retrospective analysis was to compare the results of a 270-degree wrap (Toupet, T) and a 360-degree wrap (Nissen, N) in patients with gastroesophageal reflux disease (GERD). PATIENTS/METHODS: A total of 162 patients with severe GERD and/or hiatal hernia underwent laparoscopic antireflux surgery between January 1997 and December 2000. All patients were assigned to the T group before January 2000; after January 2000, they were assigned to either the T or the N group depending on preexisting motility disorders. The pre- and postoperative gastrointestinal quality of life index (GIQLI) was assessed. RESULTS: A total of 122 patients were treated using the T procedure, and 40 patients underwent N fundoplication; 124 patients (77%) had a lower esophageal sphincter (LES) pressure of less than 15 mmHg, and 34 (21%) had a low esophageal body peristaltic pressure of less than 35 mm Hg. All of the latter 34 had undergone partial fundoplication. The average operation time was 140 +/- 5 min in the T group and 118 +/- 6 min in the N group ( P=0.03). Postoperative hospitalization averaged 3.8 days in the T group and 3.4 days in the N group. Operative complications only occurred in the T group (2%), and none of the patients died. No statistical difference was seen preoperatively or at follow-up (mean 19 months; range 4-36 months) between the quality of life score after partial versus complete wrapping (88 and 123 in the T group, 87 and 118 in the N group preoperatively and at follow-up, respectively). CONCLUSIONS: Both partial and complete wrapping offer an effective form of therapy for reflux disease with over 85% patient satisfaction.

Adult↗

PubMed2001

Lysyl oxidase-like protein from bovine aorta. Isolation and maturation to an active form by bone morphogenetic protein-1.

Recently several cDNAs have been described encoding lysyl oxidase-like proteins. Their deduced amino acid sequences are characterized by a strong similarity in the C-terminal region, corresponding to the lysyl oxidase family catalytic domain, and by marked differences in the N-terminal regions. Different biological functions have been described for lysyl oxidases in addition to their traditionally assumed cross-linking role. To answer the question of whether these different functions are carried out by different lysyl oxidases, purified and active forms of these enzymes are required. At present only the classical form of lysyl oxidase has been purified and characterized. The purpose of this study was to isolate and characterize the lysyl oxidase-like protein. In view of the strong sequence homology with the C-terminal domain of other lysyl oxidases, we chose to purify the protein from bovine aorta using antibodies specific to the N-terminal domain of the proenzyme. We have isolated a 56-kDa protein identified by amino acid sequencing as the bovine lysyl oxidase-like precursor, which is cleaved at the Arg-Arg-Arg sequence at positions 89-91 by a furin-like activity, as revealed after deblocking of the N-terminal residue. The immunopurified protein was largely inactive, but further processing in vitro by bone morphogenetic protein-1 led to an enzyme that was active on elastin and collagen substrates.

Amino Acid Oxidoreductases↗

PubMed2001

Down-regulation of lysyl oxidase-induced tumorigenic transformation in NRK-49F cells characterized by constitutive activation of ras proto-oncogene.

Several investigations have suggested a putative tumor suppressor role for lysyl oxidase because it is down-regulated in many human and oncogene-induced tumors. To address this issue we down-regulated the enzyme in normal rat kidney fibroblasts by stable transfection of its cDNA in an antisense orientation. The selected clones revealed an absence of lysyl oxidase and dramatic phenotypic changes, interpretable as signs of transformation. The antisense lysyl oxidase clones showed, indeed, loose attachment to the plate and anchorage-independent growth and were highly tumorigenic in nude mice. Moreover, we found an impaired response of the PDGF and IGF-1 receptors to their ligands. In particular, the transformed cells showed a down-regulation of both PDGF receptors and expressed the 105-kDa isoform of the IGF-1 beta receptor, which was not present in the normal control cells. The lack of response to PDGF-BB has been described as a feature of many ras-transformed phenotypes. Therefore, we looked at the status of the p21(ras). Indeed, we found a significantly higher level of active p21(ras) both during steady-state growth and prolonged starvation. Our data reveal new evidence for a tumor suppressor activity of lysyl oxidase, highlighting its particular role in controlling Ras activation and growth factor dependence.

Animals↗

PubMed2001

Effect of steroid hormones on membrane profiles of HeLa S3 cells.

The cervical carcinoma cell line, HeLa S3, was exposed to oestradiol and progesterone separately and combined in ratios similar to those of the luteal and follicular phases of the menstrual cycle. After 48 h of exposure, membrane proteins were extracted from the plasma membrane and analyzed. The lipid composition of the cells and lectin binding patterns to the cells were also assessed. The hormones had a profound effect on the HeLa S3 membrane protein profiles. Progesterone inhibited the synthesis of a wide variety of proteins while oestradiol negated this effect. Less variation between lipid profiles was noted although progesterone reduced the amount of cholesterol present. Differences in lectin binding profiles between the various treatments were noted, indicating an hormonal effect on glycosylation. Such hormonal effects on membrane composition may have implications in cervical susceptible to microbial infections.

Cell Membrane↗

PubMed2001

Constrictive bronchiolitis obliterans. Characterisation of fibrogenesis and lysyl oxidase expression patterns.

The process leading to irreversible fibrotic constriction of the bronchioles was studied in two cases of bronchiolitis obliterans (BO) after bone marrow transplantation. Because lysyl oxidase (LOX) is the main collagen cross-linking enzyme that might account for irreversible fibrosis, its expression was studied together with expression of extracellular matrix (ECM) proteins. Characteristic types of lesions could be distinguished on the basis of histological and immunohistological criteria. An inflammatory stage was characterised by infiltration restricted to the bronchioles by lymphocytes and dendritic cells. A fibro-inflammatory stage was characterised by the coexistence of a persistent immune cellular lesion pattern with further focal modelling of a sub-epithelial neo-synthesised connective matrix. LOX expression was observed at the tips of intra-luminal fibrotic protrusions, together with tenascin and cellular fibronectin. A fibrotic stage was characterised by dense ECM deposits spreading throughout the peri-bronchiolar connective tissue, resulting in bronchiole obliteration and final disappearance. In contrast to reversible cases of fibrosis, persistence of long-term LOX expression reflecting continuing fibrosing activity might account for the irreversible status of BO. Our two cases illustrated that, at inflammatory and fibro-inflammatory stages, BO may be stabilised by immunosuppressive treatment, while the persistence of LOX expression in the fibrotic stage might correspond to a disease that becomes irreversible and fatal.

Adult↗

PubMed2001

The effect of oxygen on the survival of non-Saccharomyces yeasts during mixed culture fermentations of grape juice with Saccharomyces cerevisiae.

AIMS: The effect of oxygen on the survival of Torulaspora delbrueckii and Kluyveromyces thermotolerans during mixed culture fermentations in grape juice with Saccharomyces cerevisiae was investigated. METHODS AND RESULTS: Fermentations were carried out in two simple fermentation systems differing in the availability of oxygen. At low available oxygen conditions, T. delbrueckii and K. thermotolerans began to die off after two days of mixed culture fermentation. In filtrates from 2-day-old mixed cultures, single cultures of T. delbrueckii and K. thermotolerans survived and actively produced ethanol to concentrations of approx. 65 and 70 g l-1, respectively, at low available oxygen conditions. Oxygen clearly increased the survival time and decreased the death rate of T. delbrueckii and K. thermotolerans in mixed cultures, whereas it did not affect the growth and survival of S. cerevisiae. CONCLUSION: Our results show that the deaths of T. delbrueckii and K. thermotolerans in mixed cultures at low available oxygen conditions are not due to toxic metabolites produced by the yeasts but rather to the lack of oxygen. Furthermore, they indicate that T. delbrueckii and K. thermotolerans are less tolerant to low available oxygen conditions than S. cerevisiae. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study reveals new knowledge on the mechanisms underlying the succession of yeasts during wine fermentations. This knowledge may be of importance when creating defined, mixed starter cultures for the controlled production of wines with a wide range of flavour compositions.

Carbohydrate Metabolism↗

PubMed2000

A novel SMAD4 gene mutation in seminoma germ cell tumors.

Transforming growth factor (TGF)-beta is known as an antiproliferative factor in the majority of mammalian cells, including stem germ cells. Lack of TGF-beta-induced growth inhibition has been associated with disruptions of TGF-beta receptors and SMADs. In the present study, we performed a mutational analysis of the TGF-beta signaling system, including TGF-beta receptor type I and type II and SMADs (SMAD1-SMAD7), in 20 seminoma germ cell tumors. Using reverse transcription-PCR, single-strand conformational polymorphism, and sequencing analysis, the COOH-terminal domain of SMAD4 was found to be mutated: a single thymine was inserted between nt 1521 and 1522 in 2 of 20 tumors analyzed. This addition of a thymine creates a frameshift and a new stop signal at codon 492, which leads to premature termination of the encoded protein. Such a mutation potentially abrogates signaling from TGF-beta as well as the other TGF-beta family members, including activin and bone morphogenetic protein, which all use the SMAD pathway. Immunohistological analysis confirmed the loss of expression of SMAD4 protein in the seminoma tissues with the insertional mutation. To our knowledge, this is the first description of a novel SMAD4 insertional mutation in seminoma testicular germ cell tumors. This mutational inactivation of SMAD4/COOH-terminal domain may cause TGF-beta unresponsiveness. It could thus provide a basis for understanding the potential role of the TGF-beta system in germ cell tumorigenesis.

Amino Acid Sequence↗

PubMed2000

Cryopreservation of semen from pubertal boys with cancer.

BACKGROUND: The possibility of cryopreservation of semen from adolescents has until now received only little attention. Therefore, we have investigated the possibility of cryopreservation of semen in adolescent boys with cancer. PROCEDURE: Forty-five boys, aged 13-18 years, admitted because of cancer during the period January 1, 1995 to July 31, 1998 were eligible. Semen was obtained after masturbation in the majority of the cases. In three boys, semen was preserved after penile vibration or electroejaculation in general anaesthesia. The semen samples were analysed for concentration, motility, and morphology according to the WHO guidelines. The sample was transferred into straws prior to cryopreservation at 196 degrees C in liquid nitrogen. RESULTS: Twenty-one boys delivered a semen sample for cryopreservation. Four boys were offered and accepted sperm banking but were not able to produce a sample. In 20 cases time did not allow an attempt of sperm banking, the boy was not assessed to be mature enough to deliver a semen sample, or the procedure was not accepted. The boys delivered 1-3 samples, and the total number of spermatozoa ranged from 0-210 millions. Median percentage of motile sperm was 50% (range 9-86%). Semen quality improved with age; however, a 13- year- old boy produced 75 million spermatozoa with 38% motile cells. CONCLUSIONS: Pubertal maturation should be assessed in all boys admitted for cancer, and the possibility of sperm banking should be discussed with the patient and his parents.

Adolescent↗

PubMed2000

The mouse lysyl oxidase-like 2 gene (mLOXL2) maps to chromosome 14 and is highly expressed in skin, lung and thymus.

The predicted amino acid sequence derived from a mouse expressed sequence tag (EST) contig contained two domains that are highly conserved among members of the lysyl oxidase gene family: a copper binding-site with four histidines and a catalytic domain that includes a tryptophan residue. This new cDNA sequence showed the highest level of sequence homology with the human loxl2 cDNA and suggested that it encoded the mouse equivalent of hLOXL2. The mLOXL2 gene was mapped to chromosome 14 by radiation hybrid analysis. The mLOXL2 locus was tightly linked with a LOD score over 9 to the marker D14Mit32. The mLOXL2 gene is expressed as a 4-kb mRNA in almost all tissues analyzed, with highest levels of mRNA in skin, lung and thymus.

Amino Acid Oxidoreductases↗

PubMed2000

Selective expression of lysyl oxidase (LOX) in the stromal reactions of broncho-pulmonary carcinomas.

Lysyl oxidase (LOX) is the extracellular enzyme that initiates the main pathway of collagen and elastin cross-linking. LOX has also been correlated with the ras recision gene, a putative tumour suppressor isolated from revertants of ras-transformed fibroblasts. The present study investigates the potential correlation of LOX-dependent matrix protein cross-linking in the stromal reaction of lung carcinomas, with reference to the architecture of the main stromal reactions accompanying the neoplastic breast tissues. A strong LOX expression was associated with the hypertrophic scar-like stromal reaction found at the front of tumour progression in squamous carcinomas, adenocarcinomas, large cell carcinomas, or at sites of initial extense in bronchiolo-alveolar carcinomas. In contrast, little or no LOX expression was found within the stromal reaction of invasive carcinomas, small cell carcinomas, and neuro-endocrine carcinomas. The significance of LOX expression and of the stromal reaction are discussed, in light of data that associate LOX expression with tumours displaying a rather good prognosis.

Adenocarcinoma↗

PubMed1999

Expression of deoxyuridine triphosphatase (dUTPase) in colorectal tumours.

We report the generation of 2 monoclonal antibodies (MAbs), 2B12 and 3E6, suitable for the detection of human dUTPase in routinely processed paraffin sections by immunohistochemistry. Using these MAbs, we observed nuclear expression of dUTPase in the proliferation zones of normal colorectal mucosa as well as in hyperplastic polyps. Colorectal adenomas and adenocarcinomas revealed a wide spectrum of dUTPase expression, ranging from 5 to 63% (median 42%) and from 5 to 71% of tumour cells (median 42%) respectively. Non-parametric correlation of dUTPase expression with proliferation as determined by a Ki-67 antigen-specific MAb revealed a significant and moderately strong correlation between proliferation rate and dUTPase expression in adenomas, but not in adenocarcinomas. This finding was confirmed by double-labelling immunofluorescence. Unexpectedly, we found significantly lower levels of dUTPase expression in primary colorectal carcinomas without lymph-node metastases at the time of surgery (Dukes A and B stages) than in Dukes C carcinomas. While this observation requires confirmation in larger studies, it suggests that dUTPase expression may be a negative prognostic marker in colorectal carcinomas. Moreover, these reagents should prove useful in the context of attempts to develop dUTPase inhibitors for cancer chemotherapy. Since it has been demonstrated that dUTPase expression can mediate resistance to 5-fluorouracil, it is also possible that these MAbs may be helpful in identifying patients with colorectal carcinomas resistant to adjuvant chemotherapy using this and related compounds. Int. J. Cancer (Pred. Oncol.) 84:614-617, 1999.

Adenocarcinoma↗