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Biomedical subjects

L Albert

Publications and source records attributed to L Albert.

At least 19 recordsLinked to original sources
PubMed2006

Exciton formation and annihilation during 1D impact excitation of carbon nanotubes.

Near-infrared electroluminescence was recorded from unipolar single-wall carbon nanotube field-effect transistors at high drain-source voltages. High resolution spectra reveal resonant light emission originating from the radiative relaxation of excitons rather than heat dissipation. The electroluminescence is induced by only one carrier type and ascribed to 1D impact excitation. An emission quenching is also observed at high field and attributed to an exciton-exciton annihilation process and free carrier generation. The excitons' binding energy in the order of 270 meV for 1.4 nm SWNTs is inferred from the spectral features.

Journal Article↗
PubMed2006

Formaldehyde and some fully n-methylated substances in boar seminal fluids. Short communication.

On the basis of recent observations it is supposed that seminal fluids may contain--mainly in hydroxymethyl groups--formaldehyde (HCHO) and quaternary ammonium compounds as potential HCHO generators, therefore, preliminary investigations were carried out for the identification of these compounds in pig seminal fluids using OPLC, HPLC and MALDI MS techniques. The fresh pig seminal fluid was frozen in liquid nitrogen, powdered and aliquots (0.25 g) were treated with 0.7 ml ethanolic dimedone solution. The suspension was centrifuged and the clear supernatant was used for analysis by OPLC or after dilution with HPLC or MALDI MS technique. After OPLC separation of formaldemethone the fully N-methylated compounds which are stayed on the start point were separated by OPLC using an other eluent system. It has been established that the HCHO is really a normal component of the pig seminal fluid, as well. It can be isolated and identified in dimedone adduct form. The measurable amount of HCHO depended on the concentration applied of dimedone. According to OPLC and MALDI MS investigations L-carnitine is the main quaternary ammonium compound in pig seminal fluid which can generate a protection of the sperm cells against environmental and other influences. Considerable differences have been found among individuals concerning concentrations of quaternary ammonium compounds in the seminal fluid of pigs.

Alkaloids↗
PubMed2004

Characterization of germination with physical parameters: correlation of relative mass and density as an indicator function of the germination of European Turkey oak acorn.

During germination of European Turkey oak acorn (Quercus cerris L.), a linear relationship was established between mass and density. Water take-up induced by osmotic pressure of imbibition was established to be independent of the volume of the acorn. Development of the germinating acorn can be characterized by its physical parameters of relative mass (the mass of the germinating acorn divided by its mass at the beginning of germination) and density. Linear correlation between the increment of relative mass and the decrease in density reveals an important property of the germinating acorn, namely that the slopes of the straight lines fitted to the data pairs of relative mass and density can statistically be considered as a constant. On the basis of this finding, the germinating acorns having the same values of relative mass and density can be grouped into the same developmental stage.

Biomass↗
PubMed2002

Pharmacogenomic analysis of rhIL-11 treatment in the HLA-B27 rat model of inflammatory bowel disease.

Recombinant human interleukin-11 (rhIL-11) reduces the clinical signs and histological lesions of inflammatory bowel disease (IBD) in transgenic rats expressing the human major histocompatability complex (MHC) class I allele, HLA-B27. To elucidate the pharmacogenomic effects of rhIL-11 in this model, we examined the global gene expression pattern in inflamed colonic tissue before and following rhIL-11 treatment using oligonucleotide microarrays. In total, 175 disease-related genes were identified. Increased expression of genes involved in antigen presentation, cell death and inflammation, and decreased expression of metabolic genes was associated with disease. A total of 27 disease-related genes returned to normal expression levels following rhIL-11 treatment including the MHC class II gene RT1-DMbeta. rhIL-11 induced the expression of four intestinal epithelial growth factors. These gene expression patterns indicate that treatment of inflammatory bowel disease with rhIL-11 affects class II antigen processing and colonic epithelial cell proliferation and metabolism.

Animals↗
PubMed2000

HPLC-OPLC-MS investigation of change of formaldehyde and its generators in human teeth of different physiological stage.

Taking into consideration the unquestionable intracellular occurrence of formaldehyde (HCHO) and its generators in cells of plant, animal and human organisms as well as in body fluids it was resolved to determine their levels in hard tissues of physiologically and pathologically changed teeth. The aim of the work was to determine the relationship between the level of HCHO and the levels of its generators in pathologically changed teeth, mainly carietic teeth as tooth caries is still a serious and commonly occurring problem. The occurrence of HCHO (captured as its dimedone adduct) and some of its potential generators was demonstrated in the hard tissues of healthy and pathological human teeth by means of OPLC, HPLC and MS analyses. It was established that the measurable level of HCHO was increased in the carietic teeth in comparison with healthy ones. In the case of paradontic tooth sample, a dramatic increase of HCHO was observed and at the same time the level of betaines was decreased considerably. The obtained results give a new insight into the pathology of hard tissues of teeth in strong correlation with the phases of stress syndrome.

Betaine↗
PubMed2000

Subcutaneous or oral administration of rhIL-11 modulated the contact hypersensitivity response.

Recombinant human interleukin 11 (rhIL-11) is a multifunctional cytokine with immunomodulatory activity on both T cells and macrophages. The effects of rhIL-11 in a murine model of contact hypersensitivity (CHS) response have been studied. The CHS response is a T cell-mediated response directed against chemically modified self-proteins following epidermal exposure to haptens. CHS is generated in two phases. The sensitization phase involves dermal dendritic cell recognition of haptenized proteins and antigen presentation. The effector phase involves T cell recognition and activation. In mice sensitized with oxazolone, CHS was induced by secondary challenge to the right ear and measured by ear swelling 24 h later. rhIL-11 significantly suppressed CHS as measured by ear swelling and tissue myeloperoxidase activity when injected subcutaneously for 5 days from the day of sensitization or when administered only on the day before and the day of challenge, but was not effective when administered prior to or on the day of sensitization. These results indicate that subcutaneously administered rhIL-11 may modulate the effector phase of CHS. Administration of rhIL-11 as an oral gavage prior to sensitization also reduced CHS. However oral administration of rhIL-11 after sensitization had no effect. These results suggest that orally and subcutaneously administered rhIL-11 may act through different mechanisms to affect CHS.

Administration, Oral↗
PubMed2000

Serial renal biopsy in systemic lupus erythematosus.

OBJECTIVE: To examine the role of sequential renal biopsies in patients with systemic lupus erythematosus (SLE), with regard to indications, morphologic change over time, and the clinical utility of repeat biopsies. METHODS: Patients with repeat renal biopsies were identified from the University of Toronto Lupus Clinic Database and their biopsies were reviewed blindly by a committee, using the WHO classification as well as activity and chronicity indices. Reasons for obtaining biopsy were documented, and therapeutic decisions following repeat biopsy were tabulated. RESULTS: Fifty-seven patients (49 F/9 M) had at least 2 renal biopsies between 1970 and 1994. The mean interval between biopsies was 4.2 years. The major reason for obtaining the first biopsy was disease diagnosis (32/57), while the majority of repeat biopsies were performed to discern the cause of increasing proteinuria (45/57). A comparison of the WHO classification of initial and repeat biopsies showed evolution to another class in 23 instances, but more commonly a change within a class was seen. A decrease in proliferative lesions (classes III and IV and subsets of V) was noted on repeat biopsies. The chronicity index increased significantly (p = 0.0001) and the activity index decreased (p = 0.064) between biopsies. Seventy-seven percent of patients had a change in treatment based on biopsy results. CONCLUSION: The major reason for repeat renal biopsy in patients with SLE was proteinuria. Renal morphology in patients with SLE can change with time, particularly in terms of chronicity and activity features. Repeat biopsies in patients with SLE appear to have clinical utility.

Adult↗
PubMed1998

Formaldehyde cycle and the natural formaldehyde generators and capturers.

S-adenosyl-L-methionine serves as a methyl donor in virtually all of the vast number of enzymatic transmethylation reactions including DNA methylation. On the basis of our former experiences we questioned the formation of a methyl cation or methyl radical in the enzymatic transmethylation reactions. The formation of formaldehyde from the methyl moiety of S-adenosyl-L-methionine has been demonstrated. It became increasingly evident that there is a formaldehyde cycle in biological systems in which the formation of the methyl group of L-methionine takes place through formaldehyde and the formation of formaldehyde from S-adenosyl-L-methionine is linked to different enzymatic transmethylation reactions. It is also known that during demethylation processes both formaldehyde and demethylated compound can be formed. The abnormalities of the originally controlled formaldehyde cycle and the uncontrolled enzymatic production of formaldehyde from endogenous and/or exogenous substrates may be potential risk factors in pathogenesis of different disorders. The formaldehyde generator and capturer molecules may potentially normalise these abnormal processes. Trans-resveratrol (trans-3,5,4'-trihydroxystilbene), which is as phytoalexin, occurs naturally in grapes and a variety of medicinal plants. According to our present observations it is a natural concentration-dependent formaldehyde capture molecule. It would seem that elimination of the uncontrolled formaldehyde with resveratrol may exert a double effect in biological systems. The elimination of formaldehyde with resveratrol (first step) may cause a cardioprotective effect and the reaction products between resveratrol and formaldehyde (second step) may act as a chemopreventive factor against cancer.

Formaldehyde↗
PubMed1998

Plant tissue culture as a model for study of diversity in formaldehyde binding.

The effect of endogenous formaldehyde (HCHO) deprivation with dimedone - as abiotic stress - was investigated on the methylation-demethylation reactions in Datura innoxia Mill. callus cultures. The matrix assisted laser desorption/ionization mass spectrometric (MALDI MS) investigation of the culture extracts revealed characteristic differences between the tissues cultivated in light and dark. MALDI MS data show the presence of a precursor molecule and its mono- and tri-hydroxymethyl derivative, only in the cultures maintained in light. The relative amount of the different derivatives changed considerably, as a consequence of dimedone application in the culture medium and during the extraction.

Culture Techniques↗
PubMed1998

Identification and measurement of resveratrol and formaldehyde in parts of white and blue grape berries.

The phytoalexin resveratrol (3,5,4'-trihydroxy-trans-stilbene) and formaldehyde (as its dimedone adduct, formaldemethone) have been identified and measured in the extracts of parts of white and blue grapes as well as in white and red wines by overpressured layer chromatography (OPLC), high performance liquid chromatography (HPLC) and from matrix assisted laser desorption/ionization mass spectrometric data. It has been established that the level of resveratrol was very high in skin and in some cases in the stem. Blue grape varieties and red wines always contained a considerably higher amount of resveratrol than white grapes and wines. The measurable level of formaldehyde as well as the resveratrol content was always parallelly high in the same parts of the berries, however, the formaldehyde level was higher in white grapes than in blue ones. The simultaneous occurrence of resveratrol and formaldehyde gives a possibility for interaction between these two special molecules, consequently, hydroxymethyl derivatives of resveratrol can be formed. These resveratrol derivatives may be responsible for special biological activities of resveratrol in grapes and dietetically (cardioprotective effect and chemopreventive effect against cancer) in the human organism.

Chromatography, High Pressure Liquid↗
PubMed1998

The effect of heat shock on the formaldehyde cycle in germinating acorns of European Turkey oak.

The effect of heat shock (40 degrees C) on the formaldehyde cycle has been studied in European Turkey oak (Quercus cerris L.) acorns germinated to a 10% increase in mass. Hydroxy-methyl groups bonded to sulfur, oxygen and nitrogen atoms were made to react with dimedone and the derivative obtained (formaldemethone), which represented the endogenous formaldehyde level, was determined by high performance liquid chromatography. Qualitative alterations of methyl donors and acceptors in the response of acorns to the heat shock have been mapped by MALDI (matrix assisted laser desorption ionization) mass analysis. In the first experiment the acorns were prevented from withering by wrapping them in aluminium foil and in the second they were not. The relatively high temperature of the acorns wrapped in aluminium foil was the dominant stress effect and the role of withering was subsidiary. Alteration of the endogenous formaldehyde level in the seed-leaves reflected the phases of the stress syndrome. If the withering were not hindered, two local minima in the alteration of endogenous formaldehyde level were found. First, the increase in temperature decreased the endogenous formaldehyde level and after a local maximum a repeated local minimum was observed as a delayed response. It is presumed that the second minimum was induced by the decreasing water amount becoming more and more significant in the seed-leaves.

Chromatography, High Pressure Liquid↗
PubMed1998

Changes in formaldehyde contents of germinating acorns of Quercus cerris L. under low temperature stress conditions.

Acorns of Quercus cerris L., after saturation with water and storage at -20 degrees C, were studied for changes in their contents of endogenous formaldehyde and its potential precursor and generator compounds. For the measurement of formaldehyde, after conversion to formaldemethone and some methyl acceptor and donor substances, high performance liquid chromatography (HPLC) were used. First, the amount of formaldehyde was drastically decreased. Having reached a minimum value within three to five days of the beginning of low temperature storage, a higher steady-state than the control acorns was recorded. Trigonelline and gamma-amino-butyric acid in seedleaf extracts were identified by matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS).

Chromatography, High Pressure Liquid↗
PubMed1998

Alteration of endogenous formaldehyde level following mercury accumulation in different pig tissues.

The effect of mercury accumulation on the formaldehyde cycle of different pig tissues resulted by a single dose of mercury (0.4 mg mercury in Hg(II)-chloride form, 500 kBq Hg-203/animal) has been studied. Daily mercury excretion was tracked, and having reached the steady-state mercury level of the body (10th day), samples were taken from the liver, kidney and muscle (musculus longissimus dorsi). After reaction with dimedone the endogenous formaldehyde levels in the samples were measured by high performance liquid chromatography. Our results show that the endogenous formaldehyde level decreased by more than 50% in the liver and the kidney, where the average mercury accumulation was the highest (1017 Bq/100 g and 625 Bq/100 g, respectively). In contrast, the muscle tissues, with a low mercury level (139 Bq/100 g), responded to the stress effect by about a 30% increase in their endogenous formaldehyde level.

Animals↗
PubMed1998

Molecular effects of recombinant human interleukin-11 in the HLA-B27 rat model of inflammatory bowel disease.

Recombinant human interleukin-11 (rhIL-11) is a pleiotropic cytokine with effects on multiple cell types. In addition to thrombopoietic activity, rhIL-11 has demonstrated anti-inflammatory activity in vitro and in vivo. rhIL-11 treatment reduces clinical signs and histologic lesions of colitis in transgenic rats expressing the human major histocompatibility complex (MHC) Class I allele, HLA-B27. We have investigated the effects of rhIL-11 at the molecular and cellular level in this model of inflammatory bowel disease. RT-PCR analysis of colonic RNA revealed that treatment with rhIL-11 down-regulated expression of proinflammatory cytokines including TNF-alpha, IL-1beta, and IFN-gamma. rhIL-11 also reduced the level of myeloperoxidase activity in the cecum indicating reduced inflammation. After stimulation in vitro with anti-CD3 antibody, spleen cell cultures derived from rhIL-11-treated rats produced less IFN-gamma, TNF-alpha, and IL-2 than cultures derived from vehicle-treated rats. These molecular and cellular effects correlated with amelioration of disease as measured by stool character and histologic lesion scores. These findings suggest that rhIL-11 acts to reduce inflammation through modulation of multiple proinflammatory mediators including products of activated T cells. This study has identified pharmacodynamic markers of rhIL-11 anti-inflammatory activity in vivo and supports rhIL-11 therapy to treat inflammatory bowel disease.

Animals↗
PubMed1996

Cryocrystalglobulinemia mimicking rheumatoid arthritis and vasculitis.

We describe a patient with longstanding arthropathy resembling rheumatoid arthritis (RA) and cold induced purpura for many years, concomitant with IgG kappa paraproteinemia. At autopsy, the patient was found to have evidence of widespread vascular occlusions due to precipitated crystals as well as tissue deposition of crystals. Neither vasculitis nor synovitis was observed despite the clinical picture of both. Blood and synovial fluid obtained antemortem were found to spontaneously form crystals when stored at 4 degrees C, and the washed crystals were composed of the same monoclonal IgG kappa previously found in serum. Cryocrystal formation occurred at 33 degrees C and neutral pH. This patient thus had cryocrystalglobulinemia mimicking clinical manifestations of RA and vasculitis.

Arthritis, Rheumatoid↗
PubMed1994

IL-11, a pleiotropic cytokine: exciting new effects of IL-11 on gastrointestinal mucosal biology.

Recombinant human interleukin 11 (rhIL-11) is a pleiotropic cytokine that stimulates bone marrow stem cells to proliferate and decreases intestinal mucosal injury produced by cytoablative drugs and radiation in animals. The effects of rhIL-11 were studied in a hamster model of oral mucositis and in two rat models of inflammatory bowel disease (IBD). Oral mucositis was induced in male Golden Syrian hamsters with 5-fluorouracil 60 mg/kg intraperitoneal, days 0 and 2. Peak mucositis occurred by day 10 in vehicle treated animals. rhIL-11, given twice daily subcutaneously, decreased the mucositis in a dose-dependent manner and increased animal survival at all doses tested. In two models of IBD, the acetic acid-induced acute colonic injury model in Sprague-Dawley rats and the transgenic Fischer 344 rats expressing human HLA-B27 and beta 2-microglobulin, rhIL-11 decreased the gross and microscopic damage in the colons of these animals. These data suggest that rhIL-11 exerts effects on the gastrointestinal mucosa which ameliorate responses to injurious stimuli.

Acetates↗