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Biomedical subjects

G Matejka

Publications and source records attributed to G Matejka.

15 recordsLinked to original sources
PubMed2007

Leachate recirculation effects on waste degradation: study on columns.

The purpose of this study is to determine the impact of leachate recirculation on the degradation of municipal solid wastes (bioreactor concept). The study was carried out using columns containing approximately 50 kg of waste, in order to follow waste degradation over a limited time. Three types of waste were studied: fresh waste of standard composition, fresh waste of fermentable composition and some 8-yr-old waste extracted from a site in France. Measurement of the global parameters, such as chemical oxygen demand (COD), volatile acidity, alkalinity, leachate conductivity, methane potential of the wastes and biogas production monitoring (volume of CO2 and CH4 produced), were carried out. The quantity of oxydizable matter and biogas production was increased by the leachate recirculation, and the duration of the first degradation phases was reduced in all cases. Chloride, ammonium and organic pollution accumulation was observed according to the duration of recirculation. After 400 days of degradation, waste stabilization seemed to be reached for all of the recirculated columns (COD<300 mg/L O2, and methane potential reached).

Bioreactors↗
PubMed2006

Indicating the parameters of the state of degradation of municipal solid waste.

This study related to the analysis of the physical (granulometry and composition) and chemical (organic matter, organic carbon and nitrogen contents) characteristics, as well as those relating to release (leaching tests and determining the methanogene potential) of several domestic wastes, with an aim of evaluating stabilization indicators. Values thresholds for a known stabilized waste were thus deduced by correlation (% paper-cardboard = 0-1; % volatile solid (VS) = 18-19; % OC = 5-6; % fines = 44-45; % degraded components = 75-76, COD of leachate = 141-155 mg O2/L; DOC from leachate = 45-49 mg C/L and 0.9-1 m3 CH4/t of dry waste). However, these values thresholds remain specific to the method employed for the analyses. The results obtained represent a considerable advance in the definition of a waste stabilized state and propose the importance of certain parameters, such as the paper-cardboard content and the measurement of leachates by using the SUVA index for determining a stabilization state.

Methane↗
PubMed2002

Fractionation and characterisation of dissolved organic matter from composting green wastes.

A new fractionation procedure using membrane ultrafiltration (UF), followed by chemical characterisation--measurement of total organic carbon (TOC), chemical oxygen demand (COD) and organic nitrogen and spectroscopic study--was applied to aqueous extracts of composting green wastes. Three membranes of molecular weight (MW) cut-offs of 1, 10 and 100 kDa were used. The study demonstrated the first step of the transfer of organic matter from the solids to the aqueous biofilm surrounding the solids. The microbiological consumption of the dissolved organic matter mainly used molecules smaller than 1 kDa, while the aromatisation of the organic matter, observed after 100 days composting, involved molecules larger than 10 kDa.

Biodegradation, Environmental↗
PubMed2000

Impairment of cardiac function and bioenergetics in adult transgenic mice overexpressing the bovine growth hormone gene.

Cardiovascular abnormalities represent the major cause of death in patients with acromegaly. We evaluated cardiac structure, function, and energy status in adult transgenic mice overexpressing bovine GH (bGH) gene. Female transgenic mice expressing bGH gene (n = 11) 8 months old and aged matched controls (n = 11) were used. They were studied with two-dimensional guided M-mode and Doppler echocardiography. The animals (n = 6) for each group were examined with 31P magnetic resonance spectroscopy to determine the cardiac energy status. Transgenic mice had a significantly higher body weight (BW), 53.2+/-2.4 vs. 34.6+/-3.7 g (P < 0.0001) and hypertrophy of left ventricle (LV) compared with normal controls: LV mass/BW 5.6+/-1.6 vs. 2.7+/-0.2 mg/g, P < 0.01. Several indexes of systolic function were depressed in transgenic animals compared with controls mice such as shortening fraction 25+/-3.0% vs. 39.9+/-3.1%; ejection fraction, 57+/-9 vs. 77+/-5; mean velocity of circumferential shortening, 4.5+/-0.8 vs. 7.0+/-1.1 circ/sec, p < 0.01. Creatine phosphate-to-ATP ratio was significantly lower in bGH overexpressing mice (1.3+/-0.08 vs. 2.1+/-0.23 in controls, P < 0.05). Ultrastructural examination of the hearts from transgenic mice revealed substantial changes of mitochondria. This study provides new insight into possible mechanisms behind the deteriorating effects of long exposure to high level of GH on heart function.

Acromegaly↗
PubMed1998

Feasibility of a nurse-monitored, outpatient-care programme for elderly patients with moderate-to-severe, chronic heart failure.

AIMS: To evaluate the feasibility of a nurse-monitored, outpatient-care program for elderly patients previously hospitalized with chronic heart failure. METHODS AND RESULTS: Patients with chronic heart failure hospitalized in the medical wards were screened to find those eligible for a randomized study to compare the effect of a nurse-monitored, outpatient-care programme aiming at symptom management, with conventional care. The inclusion criteria were patients classified in New York Heart Association classes III-IV, age 65 years, and eligibility for an outpatient follow-up programme. The total in-hospital population of patients discharged with a heart-failure diagnosis was surveyed. Eighty-nine per cent of all the hospitalized patients (n=1541) were 65 years old. Of these, 69% (n=1058) were treated in the medical wards which were screened. The study criteria were met by 158 patients (15%). No visits to the nurse occurred in 23 cases among the 79 patients randomized to the structured-care group (29%), mainly on account of death or fatigue. The numbers of hospitalizations and hospital days did not differ between the structured-care and the usual-care groups. CONCLUSIONS: Given the selection criteria and the outline of the interventions, the outpatient, nurse-monitored, symptom-management programme was not feasible for the majority of these elderly patients with moderate-to-severe, chronic heart failure, mainly because of the small proportion of eligible patients and the high drop-out rate. Management of these patients would have to be more adjusted to their home situation.

Aged↗
PubMed1998

Intravenous methylprednisolone pulse therapy in the treatment of Graves' ophthalmopathy.

Graves' ophthalmopathy (GO) is a specific immune-mediated disorder, whose treatment is sometimes difficult. In order to investigate the efficacy of intravenous methylprednisolone (MP) pulse therapy in GO, we studied eight patients with GO, followed up for at least 6 months by clinical patient self-assessment, ophthalmological examination and orbital computed tomography (OCT). A 12.5 mg/kg dose of MP was administered intravenously over a 10 hour period, once every month. Three to six MP pulse administrations were performed in each patient. All patients were outpatients. A 0.5 mg/kg/day oral prednisone dose was given to each patient as interpulse therapy. Clinical assessment of MP pulse therapy showed a good response in 87.5% and no response in 12.5% of patients. The treatment was rapidly efficient, mostly on patient self-assessment, soft tissue inflammation, ophthalmoplegia, corneal involvement, visual acuity and extraocular muscle enlargement on OCT. Post-treatment ophthalmic index was significantly improved (6.75 +/- 3.06 vs. 2.5 +/- 1.41: p < 0.05). MP pulse therapy had less effect on proptosis (22.94 +/- 2.32 mm vs. 21.56 +/- 2.22 mm: p < 0.05). No adverse effects were noted with MP pulse therapy. Patients showed no relapse of eye involvement during a mean follow up of 31.8 months (2-77 months). In conclusion, our results suggest that intravenous MP pulse therapy is a good immunosuppressive therapy for GO. Moreover, in comparison with the previous studies, the MP dose used in our present study appears to be optimal with high efficacy. MP pulse therapy represents a safe and efficient treatment in GO, which can easily be performed in outpatients.

Adult↗
PubMed1997

Hypertriglyceridaemia and Lewis (A-B-) phenotype in non-insulin-dependent diabetic patients.

A relationship between Lewis (a-b-) phenotype and the metabolic syndrome X has been suggested. We studied the frequency of Lewis (a-b-) phenotype in subjects with non-insulin-dependent diabetes mellitus (NIDDM) as well as the relationship between Lewis phenotype and lipid concentration in NIDDM patients. Lewis red blood cell phenotyping was done in 207 NIDDM subjects and 345 non-diabetic control subjects by immuno-agglutination with anti-Lewis a and b monoclonal antibodies. Among NIDDM patients, the proportion with the Lewis (a-b-) phenotype was significantly increased (23.6% vs 14.3%, p = 0.01), and this phenotype was associated with higher levels of triglycerides (2.40 +/- 2.58 vs 1.97 +/- 1.25, p = 0.03). This study shows a relationship between NIDDM and Lewis (a-b-) phenotype. Hypertriglyceridaemia in Lewis-negative NIDDM could suggest an increased risk of ischaemic heart disease for these subjects.

Aged↗
PubMed1996

[Thymic carcinoid tumor causing paraneoplastic Cushing syndrome. Diagnostic value of double-labelled tomoscintigraphy].

Cushing's syndromes caused by ectopic corticotropin secretion represent 10 to 15% in the causes of Cushing's syndrome. Somatostatin receptor scientigraphy can be successful in the localization of ACTH-secreting neuroendocrine tumors. We report a case of Cushing's syndrome caused by ectopic corticotropin secretion from a thymic carcinoid tumor. Conventional localization techniques failed but the tumor was detected by a double binding thoracic scintigraphy using 111Indium-octreotide and 99mTechnetium-albumine macroagregates.

Adult↗
PubMed1996

Expression of Epstein-Barr nuclear antigen 2 in kidney tubule cells induce tumors in transgenic mice.

The effect of EBNA2 in normal cells in vivo has not as yet been explored. The experiments described here were initiated to follow the consequences of the expression of EBNA2 in different tissues in transgenic mice. EBNA2 transgenic strains were generated using a vector containing EBNA2 encoding sequences under the control of the simian virus 40 (SV 40) early enhancer/promoter fused to the endogenous EBNA2 Wp promoter. Control mice carrying a transgene with the same sequence but lacking the EBV DNA part remained healthy during observation periods of up to 15 months. The SV-EBNA2 transgenic animals, however, over time developed abdominal masses that on necropsy showed to be due to kidney tumors. Histological examination revealed the presence of tumors with the morphology of kidney adenocarcinoma with a solid growth pattern. At the age of 20 weeks the kidneys of all animals investigated showed disseminated islands of tubular hyperplasia but no true malignant neoplasms. At about 50 weeks of age multiple foci of microscopic tubular adenocarcinomas were found in both kidneys. Eventually, tumors could be diagnosed in about 90% of the SV-EBNA2 transgenic mice. EBNA2-encoding RNA was expressed in both non-malignant kidney tissue and in tumors as shown by cDNA/PCR analysis. Immunoprecipitation and immunoblot analysis showed that the tumor cells contained a polypeptide of the same size as EBNA2 in B95-8 cells that reacted with a monoclonal anti-EBNA2 antibody. Immunohistochemistry demonstrated nuclear expression of EBNA2 in hyperplastic tubules and in tumor tissue.

Adenocarcinoma↗
PubMed1996

[Food-dependent Cushing syndrome: a new entity of organic hypercorticism].

Diagnosis of Cushing's syndrome is quite difficult in endocrinology. Spontaneous Cushing's syndrome is usually divided into two subgroups, one which is dependent on corticotropin (ACTH) and another one which is not. In the first class are Cushing's disease, the ectopic corticotropin syndrome and the rare ectopic corticotropin-releasing hormone (CRH) syndrome; these ACTH-dependent Cushing's syndrome have usually diffusely enlarged adrenal glands. In the second class are cortisol producing unilateral adrenocortical adenomas or carcinomas, and the recent Cushing's syndrome with food dependent periodic hormonogenesis. This food dependent Cushing's syndrome is an ACTH-independent Cushing's syndrome with multinodular enlargement of both adrenal glands. Pathogenesis is an aberrant adrenal sensitivity to physiologic secretion of gastric inhibitory peptide (GIP). Ectopic expression of GIP receptors on adrenal cells involve pathologic food induced cortisol secretion. Food dependent Cushing's syndrome is a new cause of Cushing's syndrome. Food induced cortisol secretion may have to be explored in the ACTH-independent Cushing's syndrome.

Adrenocortical Hyperfunction↗
PubMed1996

Cortisol decreases IGF-I mRNA levels in human osteoblast-like cells.

Excess levels of glucocorticoids are known to cause osteoporosis. It is speculated that the effect of glucocorticoids could be mediated via regulation of IGF-I. The aims of the present study were to detect and quantify the expression of IGF-I and/or IGF-II mRNA transcripts in human osteoblast-like cells and to investigate whether glucocorticoids regulate the expression of IGF-I mRNA transcripts in human osteoblast-like cells. Cultures of human osteoblast-like cells from trabecular bone were established. The IGF-IA and IGF-IB transcripts were detected in human osteoblast-like cells from seven out of nine patients while the IGF-II transcript was detected in human osteoblast-like cells from eight out of nine patients, as determined by RT-PCR assays. Human osteoblast-like cells, as well as human muscle tissue, expressed approximately 1/10 of the IGF-I mRNA levels found in liver, as determined by RNase protection solution hybridization assay. The IGF-I mRNA levels did not decrease with age in the human osteoblast-like cells and no difference was seen between males and females. However, cortisol (10(-6) mol/l) decreased IGF-I mRNA levels. In summary, the present study has shown that human osteoblast-like cells express IGF-I and IGF-II mRNA transcripts and that cortisol down-regulates the IGF-I mRNA levels, indicating that some of the inhibitory effect of glucocorticoids on bone formation in humans is mediated via a reduced autocrine/paracrine expression of IGF-I.

Adolescent↗
PubMed1996

[Primary hyperparathyroidism and pregnancy].

We report a case of primary Hyperparathyroidism (HPT) occuring in a 36 year old woman, during pregnancy. This woman received medical therapy to the delivery, then underwent parathyroidectomy in post-partum. Primary HPT during pregnancy is associated with increased risk of fetal loss, neonatal and maternal morbidity. Neonatal hypocalcemia is due to transient hypoparathyroidism consequent to abnormal suppression of fetal parathyroid hormone secretion by maternal hypercalcemia. Maternal hypercalcemia may be masked by hypoalbuminemia during pregnancy and often leads to aspecific symptoms which will differ the diagnosis. The recommanded treatment is parathyroidectomy which should preferably be performed during the second trimester of pregnancy; the efficacity of medical treatment is poor and transient.

Adult↗