Biomedical subjects

A Pol

Publications and source records attributed to A Pol.

At least 19 recordsLinked to original sources

PubMed2006

First record of the bat Mimon crenulatum (E. Geoffroy, 1801) (Mammalia: Chiroptera) in the state of Rio de Janeiro, Southeastern Brazil.

The present study reports an extension of the geographic range of the phyllostomid bat Mimon crenulatum. This is the first record of this species in the state of Rio de Janeiro, Southeastern Brazil. Bats were captured in two conservation units of the Atlantic Forest. Data on the ecology and morphometry of the individuals are presented and compared with data recorded for other localities. The occurrence of this bat species in the region, though new, is consistent with information on its natural history found in the literature.

Animals↗

PubMed2005

[Late thrombosis of a drug-eluting coronary stent after antiplatelet therapy discontinuation].

We reported the late thrombosis of a drug-eluting coronary stent related to discontinuation of antiplatelet therapy for venous surgery of the right leg more than half and a year after its implantation. After this acute myocardial infarction, a cardiac assistance device has to be used as a bridge to transplantation because of end stage ischaemic cardiopathy. Antiplatelet therapy management must be revisited for eluting stents, which can clot lately after its implantation.

Acute Disease↗

PubMed2003

Involvement of the liver by multiple myeloma as nodular lesions: a case diagnosed by fine-needle aspiration and immunocytochemistry.

Liver involvement by multiple myeloma as space-occupying lesions is a rare condition with only a few cases reported in the literature. We present a case of a 68-year-old man with a prostatic adenocarcinoma who developed a multiple myeloma as a second primary malignancy. Hepatic nodules were discovered in the tomographic study. Fine-needle aspiration of one of the hepatic lesions showed a pleomorphic plasmacytoid tumor. Immunocytochemistry using p63 and kappa-chain antibodies was useful in determining the plasmacytic nature of the cells.

Adenocarcinoma↗

PubMed2002

Microbial cycling of volatile organic sulfur compounds.

Microbial cycling of volatile organic sulfur compounds (VOSCs), especially dimethyl sulfide (DMS) and methanethiol (MT), is intensively studied because these compounds play an important role in the processes of global warming, acid precipitation, and the global sulfur cycle. VOSC concentrations in freshwater sediments are low due to the balance between the formation and degradation of these compounds. These reactions occur for the greater part at the oxic/anoxic interphase of sediment and water column. In contrast to marine ecosystems, where dimethylsulfoniopropionate is the main precursor of MT and DMS, in freshwater ecosystems, VOSCs are formed mainly by methylation of sulfide and to a lesser extent from the degradation of S-containing amino acids. One of the major routes for DMS and MT formation through sulfide methylation is anaerobic O-demethylation of methoxylated aromatic compounds. Inhibition studies have revealed that the major part of the endogenously produced MT and DMS is degraded anaerobically by methanogens. The major bacterial groups involved in formation and consumption of VOSCs are described.

Bacteria↗

PubMed2002

Microbial cycling of volatile organic sulfur compounds in anoxic environments.

Microbial cycling of volatile organic sulfur compounds (VOSC) is investigated due to the impact these compounds are thought to have on environmental processes like global temperature control, acid precipitation and the global sulfur cycle. Moreover, in several kinds of industries like composting plants and the paper industry VOSC are released causing odor problems. Waste streams containing these compounds must be treated in order to avoid the release of these compounds to the atmosphere. This paper describes the general mechanisms for the production and degradation of methanethiol (MT) and dimethyl sulfide (DMS), two ubiquitous VOSC in anaerobic environments. Slurry incubations indicated that methylation of sulfide and MT resulting in MT and DMS, respectively, is one of the major mechanisms for VOSC in sulfide-rich anaerobic environments. An anaerobic bacterium that is responsible for the formation of MT and DMS through the anaerobic methylation of H2S and MT was isolated from a freshwater pond after enrichment with syringate as a methyl group donating compound and sole carbon source. In spite of the continuous formation of MT and DMS, steady state concentrations are generally very low. This is due to the microbial degradation of these compounds. Experiments with sulfate-rich and sulfate-amended sediment slurries demonstrated that besides methanogens, sulfate-reducing bacteria can also degrade MT and DMS, provided that sulfate is available. A methanogen was isolated that is able to grow on DMS as the sole carbon source. A large survey of sediments slurries of various origin demonstrated that both isolates are commonly occurring inhabitants of anaerobic environments.

Acid Rain↗

PubMed2001

A caveolin dominant negative mutant associates with lipid bodies and induces intracellular cholesterol imbalance.

Recent studies have indicated a role for caveolin in regulating cholesterol-dependent signaling events. In the present study we have analyzed the role of caveolins in intracellular cholesterol cycling using a dominant negative caveolin mutant. The mutant caveolin protein, cav-3(DGV), specifically associates with the membrane surrounding large lipid droplets. These structures contain neutral lipids, and are accessed by caveolin 1-3 upon overexpression. Fluorescence, electron, and video microscopy observations are consistent with formation of the membrane-enclosed lipid rich structures by maturation of subdomains of the ER. The caveolin mutant causes the intracellular accumulation of free cholesterol (FC) in late endosomes, a decrease in surface cholesterol and a decrease in cholesterol efflux and synthesis. The amphiphile U18666A acts synergistically with cav(DGV) to increase intracellular accumulation of FC. Incubation of cells with oleic acid induces a significant accumulation of full-length caveolins in the enlarged lipid droplets. We conclude that caveolin can associate with the membrane surrounding lipid droplets and is a key component involved in intracellular cholesterol balance and lipid transport in fibroblasts.

Amino Acid Sequence↗

PubMed2001

Development and application of monoclonal antibodies against SKALP/elafin and other trappin family members.

SKALP/elafin is an epithelial proteinase inhibitor with antimicrobial properties that is not normally expressed in human epidermis, but is induced under inflammatory conditions and in some types of skin cancer. SKALP is a member of the recently described trappin gene family, which encodes a new class of proteins, characterized by a four-disulphide core and a transglutaminase substrate domain. Polyclonal antisera against SKALP have been shown to be useful for monitoring disease activity in psoriasis and tumour differentiation in squamous cell carcinoma. We developed ten different mouse monoclonal antibodies (mAbs) against synthetic peptides corresponding to a hexapeptide epitope in the transglutaminase substrate domain and three mAbs recognizing an epitope in the proteinase-inhibiting domain. The antibodies could be used with high specificity by immunohistochemistry on formalin-fixed tissue, by affinity chromatography, by Western blotting, and by enzyme-linked immunoadsorbent assay (ELISA) for the detection of SKALP/elafin. These antibodies have several advantages over existing polyclonal antisera, such as a defined epitope, the detection of full-length SKALP/elafin and unlimited supply. An antibody against the hexapeptide epitope, which is common to all known human, simian, bovine and swine trappin family members, was used to immunolocalize bovine trappins expressed in trachea, that have recently been discovered. These mAbs will serve as important new tools to measure SKALP/elafin and trappin family members in research and diagnostics.

Amino Acid Motifs↗

PubMed2001

Changes of skeletal muscle proteases activities during a chronic low-frequency stimulation period.

Modifications of muscular contractile patterns by chronic low-frequency stimulation induce structural, physiological, and biochemical transformations in fast-twitch fibers that cause them to act like slow-twitch muscle. During this transformation many changes in protein pattern appear and the proteolytic system may be involved in those changes. The activities of cathepsin L, B, H, D, the level of cystatin, as well as the calpain activity in rabbit fast-twitch muscle have been compared with those of slow-twitch muscle. The results show that fast-twitch muscle has lower cathepsin activities and higher calpain activities than slow-twitch muscle. Chronic low-frequency stimulation was applied for 24 days to fast-twitch muscles and changes in proteases and protease inhibitors (cystatin and calpastatin) were studied. After 7-14 days of stimulation, lysosomal cathepsin L, B, and D and cytoplasm calpain and proteosome activities increased several-fold. Involvement of the phagocyte cells in the protein fiber turnover was minimal. Although the turnover of contractile proteins during muscle electrostimulation takes place in synchrony with changes in the muscle proteolytic system, the stimulation period used did not attain the total transformation from fast- to slow-twitch muscle proteolytic pattern.

Acid Phosphatase↗

PubMed2001

Total orthotopic heart transplantation for primary cardiac rhabdomyosarcoma: factors influencing long-term survival.

BACKGROUND: Primary cardiac sarcomas are uncommon and rare, with an unequal distribution in the population. A dismal prognosis is usually admitted that is related to a high propensity to develop distant metastasis with survival rarely exceeding 2 years. We report a case of a patient with a primary cardiac rhabdomyosarcoma characterized by an exceptional long-term survival after surgical treatment by a total orthotopic heart transplantation. From this limited experience, we reviewed factors that may influence survival to optimize therapeutic strategy. METHODS: A 33-year-old man was found to have a 10-cm primary cardiac rhabdomyosarcoma located in the right atrium and extending to the atrioventricular groove; therefore, resection was not possible. Since no metastases were detected, the patient was scheduled for urgent cardiac transplantation, which was performed after adjuvant radiotherapy. RESULTS: Postoperative outcome was uneventful and the patient is still alive, with regular follow-up, at 102 months. CONCLUSIONS: In a case of primary rhabdomyosarcoma, heart transplantation, despite immunosuppressive therapy, can provide long-term survival and can be considered for selected patients after rigorous analysis of predictors of survival.

Adult↗

PubMed2001

[Hemodynamic instability and paraplegia after thoracotomy for excision of a cardiac pheochromocytoma].

We report the occurrence of a sustained hypotension (vasoplegia) following thoracic phaeochromocytoma surgery. Diagnosis of spinal cord injury was done by magnetic nuclear resonance (MNR) showing surgical "Horsley wax" inside the vertebral canal and ischaemic signal inside the anterior part of the spine cord. Removal of "Horsley wax" dramatically improved arterial blood pressure but did not correct all neurologic disorders. Haemodynamic disorders related to spinal cord injury are rare after thoracotomy, and may have been enhanced by the haemodynamic instability typically associated with phaeochromocytoma surgery. Early diagnosis has to be done by MNR.

Heart Neoplasms↗

PubMed2001

Pilot study with air-automated sigmoid capnometry in abdominal aortic aneurysm surgery.

BACKGROUND: and objective Ischaemic colitis can be a serious complication after aortic surgery. The paucity of clinical symptoms makes its diagnosis particularly difficult and often delayed. Automated on-line tonometry is now proposed to monitor intestinal perfusion. This study was designed to assess the use of semi-continuous sigmoid-to-arterial [P(r-a)CO(2)] PCO(2) gap monitoring in aortic surgery to detect colonic ischaemia. METHODS: This prospective clinical study was realized at the University Hospital of Lille, France, including eight males scheduled for abdominal aortic aneurysm surgery. Intraoperative and postoperative P(r-a)CO(2) values were compared with conventional monitoring and colonic mucosa aspect performed by sigmoidoscopy 48 h after surgery. Haemodynamic variables, O(2) delivery (DO(2)), O(2) consumption (VO(2)), O(2) extraction (ERO(2)), lactate, P(v-a)CO(2), P(r-a)CO(2) were measured peroperatively and every 4 h during a 48-h postoperative period. RESULTS: Intraoperative P(r-a)CO(2) values increased significantly with the highest value (4.36 +/- 3.42 kPa) observed during aortic clamping when DO(2) was the most altered. P(r-a)CO(2) continued to deteriorate after surgery with the maximal values between 8 (4.79 +/- 3.85 kPa) and 12 (4.68 +/- 3.26 kPa) h after surgery. This peak was associated with a significant ERO(2) increase counterbalancing an increase of VO(2) whereas DO2 tended to decrease. P(r-a)CO(2) values began to decrease only at the end of the study. The highest values of P(r-a)CO(2) were registered in patients with the most altered haemodynamic variables, severe ischaemic colitis along with higher hospital lengths of stay. CONCLUSION: Taken together, these data suggest that regional and automated capnometry may be easily used non-invasively to detect peroperative intestinal ischaemia in aortic surgery.

Aged↗

PubMed2001

Microbial populations involved in cycling of dimethyl sulfide and methanethiol in freshwater sediments.

Although several microorganisms that produce and degrade methanethiol (MT) and dimethyl sulfide (DMS) have been isolated from various habitats, little is known about the numbers of these microorganisms in situ. This study reports on the identification and quantification of microorganisms involved in the cycling of MT and DMS in freshwater sediments. Sediment incubation studies revealed that the formation of MT and DMS is well balanced with their degradation. MT formation depends on the concentrations of both sulfide and methyl group-donating compounds. A most-probable number (MPN) dilution series with syringate as the growth substrate showed that methylation of sulfide with methyl groups derived from syringate is a commonly occurring process in situ. MT appeared to be primarily degraded by obligately methylotrophic methanogens, which were found in the highest positive dilutions on DMS and mixed substrates (methanol, trimethylamine [TMA], and DMS). Amplified ribosomal DNA restriction analysis (ARDRA) and 16S rRNA gene sequence analysis of the total DNA isolated from the sediments and of the DNA isolated from the highest positive dilutions of the MPN series (mixed substrates) revealed that the methanogens that are responsible for the degradation of MT, DMS, methanol, and TMA in situ are all phylogenetically closely related to Methanomethylovorans hollandica. This was confirmed by sequence analysis of the product obtained from a nested PCR developed for the selective amplification of the 16S rRNA gene from M. hollandica. The data from sediment incubation experiments, MPN series, and molecular-genetics detection correlated well and provide convincing evidence for the suggested mechanisms for MT and DMS cycling and the common presence of the DMS-degrading methanogen M. hollandica in freshwater sediments.

Base Sequence↗

PubMed2001

Obligate sulfide-dependent degradation of methoxylated aromatic compounds and formation of methanethiol and dimethyl sulfide by a freshwater sediment isolate, Parasporobacterium paucivorans gen. nov., sp. nov.

Methanethiol (MT) and dimethyl sulfide (DMS) have been shown to be the dominant volatile organic sulfur compounds in freshwater sediments. Previous research demonstrated that in these habitats MT and DMS are derived mainly from the methylation of sulfide. In order to identify the microorganisms that are responsible for this type of MT and DMS formation, several sulfide-rich freshwater sediments were amended with two potential methyl group-donating compounds, syringate and 3,4,5-trimethoxybenzoate (0.5 mM). The addition of these methoxylated aromatic compounds resulted in excess accumulation of MT and DMS in all sediment slurries even though methanogenic consumption of MT and DMS occurred. From one of the sediment slurries tested, a novel anaerobic bacterium was isolated with syringate as the sole carbon source. The strain, designated Parasporobacterium paucivorans, produced MT and DMS from the methoxy groups of syringate. The hydroxylated aromatic residue (gallate) was converted to acetate and butyrate. Like Sporobacterium olearium, another methoxylated aromatic compound-degrading bacterium, the isolate is a member of the XIVa cluster of the low-GC-content Clostridiales group. However, the new isolate differs from all other known methoxylated aromatic compound-degrading bacteria because it was able to degrade syringate in significant amounts only in the presence of sulfide.

Bacteria, Anaerobic↗

PubMed2000

Epidermal growth factor-mediated caveolin recruitment to early endosomes and MAPK activation. Role of cholesterol and actin cytoskeleton.

The endocytic compartment of eukaryotic cells is a complex intracellular structure involved in sorting, processing, and degradation of a great variety of internalized molecules. Recently, the uptake through caveolae has emerged as an alternative internalization pathway, which seems to be directly related with some signal transduction pathways. However, the mechanisms, molecules, and structures regulating the transport of caveolin from the cell surface into the endocytic compartment are largely unknown. In this study, normal quiescent fibroblasts (normal rat kidney (NRK)) were used to demonstrate that epidermal growth factor causes partial redistribution of caveolin from the cell surface into a cellubrevin early endocytic compartment. Treatment of NRK cells with cytochalasin D or latrunculin A inhibits this pathway and the concomitant activation of Mek and mitotic-activated protein (MAP) kinase; however, if cells were pre-treated with filipin, cytochalasin D does not inhibit the phosphorylation of MAP kinase induced by epidermal growth factor. From these results we conclude that in NRK cells the intact actin cytoskeleton is necessary for the EGF-mediated transport of caveolin from the cell surface into the early endocytic compartment and the activation of MAP kinase pathway.

Actins↗

PubMed2000

Late endocytic compartments are major sites of annexin VI localization in NRK fibroblasts and polarized WIF-B hepatoma cells.

Annexin VI is an abundant calcium- and phospholipid-binding protein whose intracellular distribution and function are still controversial. Using a highly specific antibody, we have studied the distribution of annexin VI in NRK fibroblasts and the polarized hepatic cell line WIF-B by confocal microscopy. In NRK cells, annexin VI was almost exclusively found associated with endocytic compartments, which were defined by their ability to receive fluid-phase marker internalized from the cell surface. However, extensive colocalization of annexin VI and the endocytic marker was only observed after about 45 min, indicating that annexin VI was primarily in late endocytic compartments or (pre)lysosomes. Consistent with this, annexin VI was predominantly seen on structures that contained the lysosomal protein lgp120, although not on dense core lysosomes by electron microscopy. Two major populations of annexin VI-containing structures were present in polarized WIF-B hepatocytes. One correlated to lgp120-positive (pre)lysosomes and was still observed after treatment with brefeldin A (BFA), while the other appeared to be partially associated with Golgi membranes and was BFA-sensitive. The striking association with prelysosomal compartments in NRK and WIF-B cells suggests that annexin VI could play a role in fusion events in the late endocytic pathway, possibly by acting as a tether between membranes.

Animals↗

PubMed2000

Cellubrevin is present in the basolateral endocytic compartment of hepatocytes and follows the transcytotic pathway after IgA internalization.

The endocytic compartment of polarized cells is organized in basolateral and apical endosomes plus those endocytic structures specialized in recycling and transcytosis, which are still poorly characterized. The complexity of the various populations of endosomes has been demonstrated by the exquisite repertoire of endogenous proteins. In this study we examined the distribution of cellubrevin in the endocytic compartment of hepatocytes, since its intracellular location and function in polarized cells are largely unknown. Highly purified rat liver endosomes were isolated from estradiol-treated rats, and the early/sorting endosomal fraction was further subfractionated in a multistep sucrose density gradient, and studied. Analysis of dissected endosomal fractions showed that cellubrevin was located in early/sorting endosomes, with Rab4, annexins II and VI, and transferrin receptor, but in a specific subpopulation of these early endosomes with the same density range as pIgA and Raf-1. Interestingly, only in those isolated endosomal fractions, endosomes enriched in transcytotic structures (of livers loaded with IgA), the polymeric immunoglobulin receptor specifically co-immunoprecipitated with cellubrevin. In addition, confocal and immuno-electron microscopy identification of cellubrevin in tubular structures underneath the sinusoidal plasma membrane together with the re-organization of cellubrevin, in the endocytic compartment, after the IgA loading, strongly suggest the involvement of cellubrevin in the transcytosis of pIgA.

Animals↗

PubMed2000

EGF triggers caveolin redistribution from the plasma membrane to the early/sorting endocytic compartment of hepatocytes.

In this study, we demonstrate that, in rat liver, epidermal growth factor (EGF) is responsible for the partial redistribution of caveolin-1 from the plasma membrane into the early/sorting endocytic compartment. Highly purified endosomes and plasma membrane fractions were isolated from control rat liver and from rats injected with EGF or pIgA for different times. Whereas in subcellular fractions from control hepatocytes most of caveolin was concentrated in the plasma membrane and the receptor-recycling fractions, after EGF injection there was a significant redistribution of caveolin toward the early/sorting (CURL) endocytic fractions. The recruitment of caveolin into the endocytic compartment was not induced by pIgA.

Animals↗

PubMed2000

Methanosarcina semesiae sp. nov., a dimethylsulfide-utilizing methanogen from mangrove sediment.

Methanosarcina semesiae MD1T (T = type strain), a novel obligately methylotrophic methanogenic archaeon is described. Strain MD1T was isolated from an enrichment on dimethylsulfide inoculated with mangrove sediment. The cells were irregularly coccoid, non-motile, 1.4+/-0.2 microm in diameter and stained Gram-positive. The catabolic substrates used included dimethylsulfide, methanethiol, methanol and methylated amines, but not acetate, formate, H2/CO2 or a combination of these substrates. When cells grown on dimethylsulfide were transferred to trimethylamine or methanol and vice versa, a lag phase was observed. The same lag phase occurred when cells grown on trimethylamine were transferred to methanol and vice versa, indicating that for each substrate different enzymes were induced. Fastest growth occurred within a temperature range of 30-35 degrees C and a pH of 6.5-7.5. Both Na+ and Mg2+ were required for growth, with maximum growth rates at 200-600 mM Na+ and 20-100 mM Mg2+. The cells exhibited specific growth rates (h-1) of 0.07+/-0.02, 0.15+/-0.04 and 0.18-/+0.05 on dimethylsulfide, methanol and trimethylamine, respectively. Analysis of the 16S rRNA gene sequence showed that strain MD1T was phylogenetically closely related to members of the genus Methanosarcina, but clearly differed from all described species of this genus (94-97% sequence similarity).

Culture Media↗