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T Kovács

Publications and source records attributed to T Kovács.

At least 19 recordsLinked to original sources

Stress related changes of cell surface hydrophilicity in Bacillus subtilis.

The changes of cell surface hydrophilicity in Bacillus subtilis were analyzed in response to oxygen-limitation, heat shock, salt stress, pH-shock, phosphate- and carbon-limitation. Although cell surface hydrophilicity varied during growth phases, an increase of surface hydrophilicity was observed under several of these stress conditions. An observed drop in intracellular GTP and/or ATP may be an element of the signal transduction pathway leading to an increase in surface hydrophilicity in response to environmental stresses. Attachment of cells to soil particles under salt stress conditions is strongly influenced by the degS/degU two-component system, which thereby provides a mechanism for the bacteria to escape from the hostile environment.

Bacillus subtilis↗

Role of iron in the interaction of red blood cells with methylglyoxal. Modification of L-arginine by methylglyoxal is catalyzed by iron redox cycling.

Diabetes mellitus is characterized by increased methylglyoxal (MG) production. The aim of the present study was to investigate the role of iron in the cellular and molecular effects of MG. A red blood cell (RBC) model and L-arginine were used to study the effects of MG in the absence and presence of iron. Intracellular free radical formation and calcium concentration were measured using dichlorofluorescein and Fura-2-AM, respectively. Effects of MG were compared to the effect of ferrous iron. Reaction of L-arginine with MG was investigated by electron spin resonance (ESR) spectroscopy and by a spectrophotometric method. MG caused an iron dependent oxidative stress in RBCs and an elevation of the intracellular calcium concentration due to formation of reactive oxygen species. Results of co-incubation of MG with ferrous iron in the RBC model suggested an interaction of MG and iron; one interaction was a reduction of ferric iron by MG. A role of iron in the MG-L-arginine reaction was also verified by ESR spectroscopy and by spectrophotometry. Ferric iron increased free radical formation as detected by ESR in the MG-L-arginine reaction; however, ferrous iron decreased it. The reaction of MG with L-arginine yielded a brown product as detected spectrophotometrically and this reaction was catalyzed at a lower rate with ferric iron but at a higher rate with ferrous iron. These data suggest that MG causes oxidative stress in cells, which is due at least in part to ferric iron reduction by MG and to the modification of amino acids e.g. L-arginine by MG, which is catalyzed by iron redox cycling.

Arginine↗

All three splice variants of the human sarco/endoplasmic reticulum Ca2+-ATPase 3 gene are translated to proteins: a study of their co-expression in platelets and lymphoid cells.

The molecular cloning of two previously unknown human sarco/endoplasmic reticulum Ca(2+)-ATPase 3 (SERCA3) 3'-end transcripts, 3b and 3c, has been recently published. Data were lacking, however, for the presence of these SERCA3 variants in different tissue or cell types at the protein level. Here we report the co-expression of three human SERCA3 protein isoforms in platelets and T lymphoid Jurkat cells. Isoform-specific polyclonal anti-peptide antibodies have been generated that recognize specifically the SERCA3a, 3b or 3c splice variants at their C-termini, and this has been confirmed by peptide-competition experiments as well. None of these antibodies cross-reacted with the housekeeping SERCA2b isoform co-expressed endogenously with SERCA3 proteins in non-muscle cells. Although all three SERCA3 isoforms could be detected in platelets, the 3a form was the most abundantly expressed species. Its size matched the apparent size of SERCA3a over-expressed in HEK-293 cells. Immunoprecipitation of the SERCA3 variants from platelet membranes using a PL/IM 430-affinity matrix provided evidence that the putative pan-anti-SERCA3 antibody, PL/IM 430, recognizes all SERCA3 protein isoforms. The epitope for the PL/IM 430 antibody could be localized in a 40 kDa N-terminal tryptic fragment common to all three SERCA3 variants. Comparative Western-blot analysis showed that the expression level of the SERCA3a, 3b and 3c isoforms was more than 10 times lower in Jurkat cells than in platelets, whereas expression of the ubiquitous SERCA2b was nearly identical. This work highlights new Ca(2+)-transporting proteins of haematopoietic cells and provides specific antibodies for their detection.

Alternative Splicing↗

[Endothelial dysfunction].

The endothelium is a major regulator of vascular tone, releasing vasoconstrictive (endothelin, cyclooxigenase-dependent factors, including prostanoids and oxygen free radicals) and vasodilating (endothelium--derived nitric oxid, endothelium--derived hyperpolarizing factor) mediators. These biologically active substances control not only the vascular tone but the vascular structure and permeability, coagulation and fibrinolysis, as well inflammatory response of the vascular wall. In endothelial dysfunction the balance in the endothelial production of vasodilating and vasoconstricting substances is altered resulting an apparent decrease in endothelium-dependent relaxations. Endothelial dysfunction is an important event in the pathogenesis of the early phase of atherosclerosis and hypertension. The testing and monitoring of endothelial dysfunction include tests of endothelium-dependent vasomotion, as well as circulating markers of endothelial damage. Further methods are needed to build up a panel of tests which measure the extent of endothelial dysfunction (= subclinical atherosclerosis), predict the subsequent risk and response to therapy.

Animals↗

[The "watermelon" stomach as a rare cause of upper gastrointestinal bleeding].

The watermelon stomach is a rare subtype of the gastric vascular malformations of unknown origin. It can usually be observed with autoimmune diseases, but in can be associated with other conditions. It is significant, since it can cause chronic iron-deficiency anaemia or sometimes serious acute blood loss. The typical endoscopic picture is linear red streaking of the antrum with convergence at the pylorus with visible tortuous small vessels. Histological examination is frequently not diagnostic. It demonstrates specific features including dilated mucosal capillaries with focal thrombi, dilated submucosal venous plexus and fibromuscular hyperplasia of the lamina propria. Therapy mostly is endoscopic, but some medical possibilities are also known. In their paper they report two cases of watermelon stomach, the lesions were successfully treated with oestrogen-progesterone compounds.

Aged↗

Olfactory centres in Alzheimer's disease: olfactory bulb is involved in early Braak's stages.

In Alzheimer's disease (AD), neurofibrillary tangles spread from the entorhinal cortex to the limbic system, then to neocortical areas, according to the Braak's stages. Olfaction is impaired in early stages of AD. The aim of this study was to describe the pathology of the cortical olfactory centres in relation to Braak's stages determining the earliest site of pathology. We examined 15 control and 15 AD cases. The primary olfactory cortices were involved in more advanced Braak's stages, while olfactory bulbs were damaged in very early (i.e. Braak's stage 0 or 1) stages. These results are supporting the fact that olfaction might be an early marker in AD and argues against the hypothesis that AD pathology is spreading through the olfactory system.

Aged↗

Endoscopy and autopsy follow-up of biodegradable oesophageal anastomoses in dogs.

The biofragmentable Anastomosis Ring (BAR) is a mechanical device composed of absorbable material and creates an inverting, atraumatic compressive anastomosis with no foreign material at the anastomotic site after healing. The aim of the present experimental study was to assess the safety of oesophagoscopy in early days after oesophageal anastomoses performed with the BAR and to follow-up the healing of BAR anastomoses by in vivo endoscopy and autopsy examination. Thirty mongrel dogs divided into subgroups according to the time-points of endoscopy and autopsy (4th, 7th, 14th, 28th day) were used. There was no significant difference in the healing of anastomoses performed under or above the tracheal bifurcation. Pleural adhesions helped to cover and seal small subclinical leaks. The mortality was 13.3% (4 dogs) and the overall leakage rate 14.3%. We looked for bleeding, haematoma, erosion, ulceration and granulation tissue in the anastomosis. Due to the high mechanical strength of these anastomoses, oesophagoscopy was a safe, easy and feasible method for follow-up BAR intrathoracic anastomoses, with no significant difference between the number of lesions found with endoscopy as compared to the autopsy data. The overall sensitivity of oesophagoscopy to discover mucosal lesions was 73.1%. Endoscopy had no complications, therefore it is a useful method of follow-up and may help predict the normal or compromised healing of oesophageal anastomoses.

Absorbable Implants↗

[Malignant and semimalignant small intestinal tumors--illustrated by two cases].

The authors review two cases of small bowel tumor. The first patient was operated electively with small bowel carcinoid causing multiplex liver metastases. The second patient was admitted because of massive gastrointestinal bleeding. After some diagnostic procedures bleeding of the small intestine was diagnosed. Urgent operation was performed and a bleeding jejunal tumor was removed. Gastrointestinal stroma cell tumor of the small bowel was found at histology. In connection with the patients some points about malignant small intestine tumors are analysed based on literature.

Aged↗

[Desmoid tumors in three patients].

Desmoids are rare tumors of the connective tissue. It develops about 1:1000 times more in patients with familial adenomatous polyposis (FAP, Gardner syndrome) compared to normal population. It has been shown in molecular genetic examinations, that different mutations of the APC gene are responsible for desmoid tumors in FAP. It means, that this disease is one of the extraintestinal manifestations of Gardner syndrome. This tumor has high recurrence rate and is growing rapidly, and as a result it is the second most common cause of death in FAP patients. That is why genetic examination for FAP patients is advised to decide if the patient has higher risk for desmoid formation. If the result of the genetic test is positive, it is advisable to try to slow the progression of polyposis with medical treatment, and so to delay the date of the colectomy because the surgical intervention--and connective tissue damage--can induce desmoid formation in these patients. At the same time it is reasonable to examine and regularly control patients with sporadic desmoid tumors searching for other manifestations of Gardner syndrome (colon, stomach and duodenum polyposis, tumor of papilla Vateri, retinopathy, etc.). Palliative surgery is not indicated in patients with inoperable intraabdominal desmoid tumors, because partial resections (R1, R2, debulking) result in further tumor progression. In these patients medical treatment (sulindac, tamoxifen), chemotherapy (doxorubicin, dacarbazin) and radiotherapy or combination of them can result tumor remission. We describe our three patients (an abdominal wall desmoid four years following Cesarean section; a desmoid tumor in the retroperitoneum and in the pelvis diagnosed three years after total colectomy; and a retroperitoneal and abdominal wall desmoid one year after total colectomy) and etiology, diagnosis and therapy of desmoid tumors are discussed.

Abdominal Muscles↗

Bursting strength and collagen content changes in esophageal anastomoses. Comparative experimental study in dogs.

BACKGROUND AND AIMS: The Biofragmentable Anastomosis Ring (BAR) is a mechanical device composed of absorbable material, performs an inverted anastomosis by atraumatic compression. It is a safe method recommended for bowel ends covered by serosal layer. The feasibility for esophageal surgery hasn't been proved. In our study we compared the healing of transsected intrathoracic esophagus anastomosed with BAR versus Stapler on an experimental dog model by evaluating the bursting strength (BS) and collagen (Hydroxyproline (HP)) concentration and content in different sites and defined time points after surgery (4th, 7th, 14th, 28th day). MATERIAL AND METHODS: Forty-six mongrel dogs were randomly separated into two groups (28 BAR, 18 Stapler) and parameters of surgical repair evaluated after sacrification on certain days. RESULTS: Although we had a total of 4 leaks (14,3%) only in the BAR group (2 were clinically relevant and fatal), there was no significant difference in the leakage rate between the two groups. BS was significantly higher in the BAR group during the first week with values almost equal from the 14th day, in both groups. BS measurement reflects anastomotic strength only during the first two postoperative weeks. After this rupture is often produced outside the anastomotic line. HP concentration showed no significant differences from samples taken next to and far from the anastomotic line. The HP rate showed a significant reduction in the 4th and 7th day subgroups, and values close to the reference from the 14th day with both techniques. CONCLUSIONS: BS and HP changes proved a normal tissue repair with no significant difference, showing that both methods are suitable to perform anastomoses on the intrathoracic esophagus in mongrel dogs. The higher mechanical stability of the BAR anastomosis could suggest the feasibility of the method in conditions where higher mechanical strength is requested.

Anastomosis, Surgical↗

Association of a uteroglobin polymorphism with rate of progression in patients with IgA nephropathy.

Uteroglobin gene-disrupted mice develop a nephritis very similar to immunoglobulin A (IgA) nephropathy. Megsin codes for a protein overexpressed in mesangium in patients with IgA nephropathy. Both are candidate genes that might have variants associated with an accelerated progression in patients with IgA nephropathy. We performed an association study of patients with IgA nephropathy and matching control subjects to test whether the G38A polymorphism in the uteroglobin gene, the C2093T polymorphism in the megsin gene, or the angiotensin-converting enzyme (ACE) insertion/deletion polymorphism is associated with IgA nephropathy or rate of disease progression in patients with IgA nephropathy. Of 110 patients with IgA nephropathy, 87 patients were followed up for at least 3 years for the progression study. We also studied 104 healthy volunteers. The uteroglobin, megsin, and ACE polymorphisms were not distributed differently in the 110 patients with IgA nephropathy compared with healthy controls; Hardy-Weinberg equilibrium criteria were fulfilled. The GG genotype of the G38A uteroglobin polymorphism was more common in patients with progression (odds ratio [OR], 3.5; P< 0.006) than the AG+AA genotypes. The G allele was also more common (OR, 2.6; P< 0.009) in patients with versus without progression. The 1/serum creatinine over time plot (in deciliters per milligram per day) was sevenfold steeper in GG patients than the other two genotypes (P = 0.08). No significant associations with disease progression were found for the other gene polymorphisms, and a multivariate analysis showed no interactions. We suggest the hypothesis that the uteroglobin gene contains variant(s) with a bearing on progression rate in patients with IgA nephropathy.

Adult↗

[Surgical management of villous and tubulovillous adenomas of the rectum].

One hundred four cases of middle and low rectal villous and tubulovillous adenomas have been operated on with transanal polypectomy (8), transanal endoscopic microsurgery--TEM (80), anterior rectum resection with double stapled straight sigmoideorectosomy (7), and deep rectum resection, bi-directional mucosectomy and hand sutured straight sigmoideoanostomy (9). The option of the authors to remove the tumours in 5 cm to the dentate line are the transanal polypectomy or transanal mucosectomy corresponding to their size. The transanal endoscopic microsurgical technic is recommended to manage the polyps smaller than 4 to 5 cm in the middle rectum. The best radicallity in removal of the circular, extended villous adenomas could be achieved with deep rectum resection, bi-directional mucosectomy and transanal straight, hand sewn sigmoideoanostomy.

Adenoma, Villous↗

Alpha-2-macroglobulin intronic polymorphism is not associated with autopsy-confirmed late-onset Alzheimer's disease.

Alpha-2-macroglobulin (A2M) intronic polymorphism has recently been reported to be associated with late-onset Alzheimer's disease (LOAD). To corroborate this association, we analysed the A2M and apolipoprotein E (APOE) polymorphisms in autopsy cases of the MRC Alzheimer's Disease Brain Bank, Institute of Psychiatry, London. The frequencies of the insertion and deletion alleles in AD were 0.81 and 0.19, respectively, and these were not significantly different from control frequencies. After pooling the AD cases in epsilon4 positive and negative subgroups, there was again no significant difference between the A2M allele frequency in the two subgroups. In our present study, we were unable to corroborate the association between A2M intronic polymorphism and LOAD in autopsy cases.

Age of Onset↗

[Comparative study of the reno-protective effect of short- and long-acting antihypertensive agents in IgA nephropathy].

The progression of IgA-NP is influenced unfavourably by development and existence of hypertension. The treatment of hypertension (HTN) has an important role in these patients. Both short- and long-acting formulations of angiotensin convertase enzim inhibitors (ACEi) and calcium channel blockers (CCB) lower blood-pressure, however long-acting preparations may provide better control and may have more renoprotective effect. Verifying this hypothesis, 22 IgA-NP patients were followed for 7.25 +/- 2.36 years. The patients were on short-acting ACEi (captopril, n = 9) or dihydropyridine type CCB (nifedipin, n = 2) or both (captopril + nifedipine n = 11), after at least 3 years the medication was changed to long-acting ACEI (enalapril, n = 4; cilazapril, n = 1), or non dihydropyridine type CCB (diltiazem hydrochlorid, n = 1) or both (n = 16). Just before changing the medication these patients underwent 24 hour ambulatory blood pressure monitoring and at the same time the level of proteinuria and the creatine clearance were measured. Values of serum-creatinine were measured in every 3-4 months within a 3 years period before and after the exchange of antihypertensive drugs. The regression of 1/creatinine was a = -5.28.10(-5) +/- 1.16.10(-4) before and a = 1.03.10(-4) +/- 2.05.10(-4) after the change of medication. Using paired t-test there was a significant difference between the regressions of 1/creatine (p < 0.005). Systolic blood pressure (SBP) (128 +/- 81 Hgmm vs. 126.09 +/- 11.67 Hgmm) was not different, however, diastolic blood pressure (DBP) (84.15 +/- 7.94 Hgmm vs. 79.78 +/- 7.17 Hgmm), diastolic percent time elevation index (HTI) (43.58 +/- 23.57% vs. 25.61 +/- 20.1%) and 24-hour diastolic hyperbaric impact (114.71 +/- 81.9 vs. 51.51 +/- 51.4, p < 0.05) was lower with long-acting antihypertensive agents, as was the proteinuria (1.18 +/- 0.94 g/die vs. 0.69 +/- 1.08 g/die, p < 0.05). Diurnal variation and systolic percent time elevation index were not different. We conclude that long-acting ACEi and non dihydropyridine type CCB formulations result in better outcomes in IgA nephropathy patients compared to short-acting drugs, probably because of better and smoother blood pressure control, lowering of proteinuria and better compliance of the patients.

Adult↗

beta-amyloid deposition and neurofibrillary tangle formation in the olfactory bulb in ageing and Alzheimer's disease.

Impaired olfaction, hyposmia or anosmia are part of the clinical phenotype in neurodegenerative disorders including Alzheimer's disease (AD). It has been proposed that the most severely affected areas are interconnected with the central olfactory system in contrast to the relative sparing of other sensory areas which lack olfactory connections. The pathology of the first synaptic relay in the olfactory pathway, the olfactory bulb (OB), has been studied in AD, but the results have been inconsistent. In order to define more fully the pathology of the OB, we analysed 15 AD and 15 control cases, using amyloid and tau immunohistochemistry on serial sections. This study demonstrates for the first time that all layers of the OB are severely affected in AD and in normal ageing. The principal effector cells of the OB, the mitral cells, developed neurofibrillary tangles (NFTs) both in AD and in controls. All the cases, with the exception of two of the controls, contained NFTs. Amyloid immunoreactivity was detected in diffuse, primitive, classical and compact deposits in AD, while five control cases contained mainly diffuse deposits. We did not find a correlation between amyloid deposition and NFT formation. Among the control cases, two contained neither amyloid nor NFTs, eight had NFTs but no amyloid and only five had both NFTs and amyloid. All the AD cases had NFT and amyloid deposition. Our data suggest that the earlier pathology in the OB is NFT formation and more than ten NFTs/section is compatible with 93.3% diagnostic accuracy for AD.

Aged↗

Ambulatory blood pressure monitoring and progression in patients with IgA nephropathy.

BACKGROUND: Hypertension is a recognized marker of poor prognosis in IgA nephropathy. METHODS: The present study investigated the prevalence of white-coat hypertension, the diurnal rhythm of blood pressure (BP), the effectiveness of antihypertensive drug therapy, and the effect of the above on the progression of the kidney disease in IgA nephropathy. One hundred twenty-six IgA nephropathy patients were selected consecutively for 24-h ambulatory blood pressure monitoring (ABPM). Fifty-five patients were normotensive and 71 were treated hypertensives. Their antihypertensive drugs were angiotensin-converting enzyme inhibitors (ACEI) alone or in combination with calcium-channel blockers (CCB). RESULTS: The mean night-time BP of normotensives (108+/-9/67+/-6 mmHg) was significantly lower than their day-time BP (125+/-8/82+/-7 mmHg, P<0.05). There was no significant difference between the mean day-time and night-time BP in hypertensive patients (125+/-9/82+/-7 mmHg vs 128+/-10/85+/-9 mmHg). The circadian variation of BP was preserved ('dippers') in 82% of the normotensive and 7% of the hypertensive patients (P<0.001). There were 10 'white-coat hypertensives' among the patients classified as normotensives with ABPM (mean office blood pressure 149+/-7/96+/-8 mmHg, 24-h blood pressure 127+/-6/83+/-5 mmHg, P<0.05) and 14 among treated hypertensives (mean office BP 152+/-8/98+/-6 mmHg, 24-h BP 130+/-4/85+/-8 mmHg, P<0.05). There was no difference in mean day-time BP among normotensive and treated hypertensive patients (125+/-8/81+/-5 mmHg vs 128+/-10/85+/-9 mmHg). Hypertensives had significantly higher night-time BP (125+/-9/85+/-9 mmHg) than normotensives (108+/-9/67+/-6 mmHg, P<0.001). There was no difference in serum creatinine levels among the different groups at the time of the ABPM. However, thirty-six+/-4.1 months after the ABPM, hypertensive patients (n=52) had higher serum creatinine levels (124+/-32 micromol/l) than at the time of the ABPM (101+/-28 micromol/l). The serum creatinine of normotensive patients (n=43) did not change during the follow-up period. 'Non-dipper' normotensives (n=10) had significantly higher serum creatinine levels at the end of the follow-up period than at its beginning (106+/-17 micromol/l vs 89+/-18 micromol/l, P<0.05). There was no increase in serum creatinine of 'dipper' normotensives. The mean serum creatinine of 'white-coat hypertensives' was significantly higher at the end of the study period than at its beginning. CONCLUSIONS: There is no diurnal blood pressure variation in most of the hypertensive IgA nephropathy patients. ACEI and CCB treatment have better effect on day-time than night-time hypertension. The lack of the circadian rhythm and 'white-coat hypertension' seems to accelerate the progression of IgA nephropathy.

Adult↗