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J Farkas

Publications and source records attributed to J Farkas.

At least 19 recordsLinked to original sources
PubMed2003

Behavioral and neuroendocrine actions of the Met-enkephalin-related peptide MERF.

The effects and the mediation of the action of the proenkephalin derivative Met(5)-enkephalin-Arg(6)-Phe(7) (MERF) on the hypothalamo-pituitary-adrenal (HPA) system and open-field behavior were investigated in mice. Intracerebroventricular injection of the heptapeptide increased square crossing, rearing, and plasma corticosterone level. To characterize the receptors involved in these neuroendocrine processes, animals were pretreated either with the nonselective opioid antagonist naloxone or the kappa-antagonist nor-binaltorphimine (nor-BNI). Both antagonists dose-dependently attenuated the HPA activation elicited by MERF. Naloxone also blocked the behavioral responses, but nor-binaltorphimine did not elicit a significant inhibition. The dopamine antagonist haloperidol and a corticotropin-releasing hormone (CRH) antagonist were also preadministered to shed light on the transmission of the actions of MERF. Both the motor responses and the HPA activation were diminished by the preadministration of the CRH antagonist, while haloperidol attenuated only square crossing and rearing. To investigate the direct effect of MERF on the dopaminergic system, dopamine release of striatal slices was measured in a superfusion system. Neither the basal nor the electric impulse-evoked dopamine release was modified by MERF. The results suggest that opioid-mediation predominate in the neuroendocrine actions of MERF, and the effect of the heptapeptide on the HPA system seems to be mediated by kappa-receptors. In the behavioral responses evoked by MERF, both CRH release and the action of the dopaminergic neurons of the subcortical motor system might be involved. MERF also appears to activate the paraventricular CRH neurons, but dopaminergic transmission does not seem to play a significant role in its hypothalamic action.

Analysis of Variance↗
PubMed2002

Comparison of the binding of [(3)H]nociceptin/orphaninFQ(1-13)NH(2), [(3)H]nociceptin/orphaninFQ(1-17)OH and [(125)I]Tyr(14)nociceptin/orphaninFQ(1-17)OH to recombinant human and native rat cerebrocortical nociceptin/orphanin FQ receptors.

Nociceptin/orphanin FQ (N/OFQ) is a 17-amino acid endogenous neuropeptide ligand for the nociceptin receptor (NOP). We have prepared a [(3)H]-labelled truncated N/OFQ peptide, [(3)H]N/OFQ(1-13)NH(2) and compared its binding characteristics with [(3)H]N/OFQ(1-17)OH and [(125)I]Y(14)N/OFQ(1-17)OH in membranes prepared from Chinese hamster ovary cells expressing the recombinant human NOP (CHO(hNOP)) and the rat cerebrocortex. [(3)H]N/OFQ(1-13)NH(2), [(3)H]N/OFQ(1-17)OH and [(125)I]Y(14)N/OFQ(1-17)OH binding to CHO(hNOP) was concentration dependent and saturable with receptor density (B(max)) and radioligand equilibrium dissociation constant (pK(d)) values (mean +/- SEM) of 1043 +/- 58 fmol/mg protein and 10.35 +/- 0.03, 1348 +/- 44 fmol/mg protein and 10.06 +/- 0.04, and 1169 +/- 76 fmol/mg protein and 10.45 +/- 0.06, respectively. In the rat, B(max) and pK(d) values for [(3)H]N/OFQ(1-13)NH(2) and [(3)H]N/OFQ(1-17)OH were 130 +/- 1 fmol/mg protein and 10.70 +/- 0.03, and 157 +/- 4 fmol/mg protein and 10.34 +/- 0.02, respectively. The binding of all radioligands was displaced by a range of peptide and non-peptide ligands. There was a strong correlation (r(2) = 0.92, P = 0.002) between pK(i) values estimated with [(3)H]N/OFQ(1-13)NH(2) and [(3)H]N/OFQ(1-17)OH. No such correlation was observed in comparison with the [(125)I]-labelled peptide (poor agreement with low affinity N/OFQ(1-9)NH(2), Dynorphin-A and Naloxone benzoylhydrazone). We suggest that [(3)H]N/OFQ(1-13)NH(2) may be a useful alternative to [(3)H]N/OFQ(1-17)OH.

Animals↗
PubMed2002

Modelling microbial growth in structured foods: towards a unified approach.

Historically, the ability of foods to support the growth of spoilage organisms and food-borne pathogens has been assessed by inoculating a food with an organism of interest, and following its growth over a period of time. Information gained from such challenge tests, together with knowledge of the organoleptic stability of the product, can then be used to determine an appropriate shelf-life for the food. Whilst this approach may be seen as the "gold-standard" of microbiological assessment of food, it is both time-consuming and costly. A major advance to complement challenge testing was the development of predictive modelling, when it was demonstrated that the growth of a wide range of organisms of interest could be quite accurately modelled as a function of only a few environmental parameters-primarily temperature, pH and water activity (a(w)), with perhaps other factors such as nitrite, organic acids and oxygen. This approach to predictive microbiology is embodied in software tools such as the UK Food MicroModel and the Pathogen Modeling Program from the USA. Whilst modelling of this form yields accurate predictions of the growth of organisms in the majority of foods, there are occasions when there are discrepancies between the model and the observed growth. These discrepancies are most often described as "fail-safe", i.e. the observed growth is slower than predicted by the model. This paper examines the role of food structure in the development of microbial populations and communities, and describes the methodologies we propose to begin to tackle some of these complex and interlinked issues.

Bacteria↗
PubMed2002

Luminometric and differential scanning calorimetry (DSC) studies on heat- and radiation inactivation of Bacillus subtilis luxAB spores.

A bioluminescent derivative of Bacillus subtilis containing a plasmid encoding a luxAB fusion under control of a vegetative promoter and gives bioluminescence upon addition of an exogenous long-chain aldehyde has been used as test organism. Its spore populations have been produced and their heat- and radiation survival curves established. Heat-sensitization effect of pre-irradiation of spores was proven not only by colony counting but also with differential scanning calorimetry. Under a linearly programmed temperature increase, the heat destruction of spores surviving 2.5 kGy gamma irradiation resulted in at a few centigrade lower temperature than that of untreated spores. Heat denaturation endotherms in the DSC-thermogram of irradiated spores were shifted to lower temperatures as well. Comparative turbidimetric, luminometric and phase-contrast microscopic studies of untreated, heat-treated and irradiated spore populations showed that the kinetics of germination and the light emission during germination of radiation-inactivated spores were the same as those of untreated spores, revealing that the pre-formed luciferase enzyme packaged into the spores during sporulation remained intact after an irradiation dose causing 90% decrease in number of colony forming spores. Therefore, in contrast to heat-treated spores, the initial bioluminescence reading upon germination of irradiated spores does not reflect the viable count of their population.

Bacillus subtilis↗
PubMed2002

Analysis of the random distribution of station-tested pigs based on their genetic merit.

The analysis was conducted on the national database of the station tests carried out between May 1996 and February 2001, using the Hungarian Large White (LW) and Hungarian Landrace (LR) breeds, and the A-line of the Ka-Hyb hybrid (MLW). Days of test, total amount of feed consumed and valuable cuts were taken into the analysis to test the random distribution of the animals' phenotypic measurements and predicted breeding values across the contemporary groups of origin. The phenotypic measurements of all traits were clearly positively associated with the herds of origin (b = 0.52-1.08). Animals with favourable phenotypic measurements originated from better herds. On the contrary, the predicted breeding values seemed to be independent of the herd effects (b = -0.16-0.08) and suggested a possible random distribution across the contemporary groups.

Analysis of Variance↗
PubMed2001

Comparison of diameter and perimeter methods for tumor volume calculation.

PURPOSE: Lesion volume is often used as an end point in clinical trials of oncology therapy. We sought to compare the common method of using orthogonal diameters to estimate lesion volume (the diameter method) with a computer-assisted planimetric technique (the perimeter method). METHODS: Radiologists reviewed 825 magnetic resonance imaging studies from 219 patients with glioblastoma multiforme. Each study had lesion volume independently estimated via the diameter and perimeter methods. Cystic areas were subtracted out or excluded from the outlined lesion. Inter- and intrareader variability was measured by using multiple readings on 48 cases. Where serial studies were available in noncystic cases, a mock response analysis was used. RESULTS: The perimeter method had a reduced interreader and intrareader variability compared with the diameter method (using SD of differences): intrareader, 1.76 mL v 7.38 mL (P < .001); interreader, 2.51 mL v 9.07 mL (P < .001) for perimeter and diameter results, respectively. Of the 121 noncystic cases, 23 had serial data. In six (26.1%) of those 23, a classification difference occurred when the perimeter method was used versus the diameter method. CONCLUSION: Variability of measurements was reduced with the computer-assisted perimeter method compared with the diameter method, which suggests that changes in volume can be detected more accurately with the perimeter method. The differences between these techniques seem large enough to have an impact on grading the response to therapy.

Brain↗
PubMed2001

Utility of perfusion-weighted CT imaging in acute middle cerebral artery stroke treated with intra-arterial thrombolysis: prediction of final infarct volume and clinical outcome.

BACKGROUND AND PURPOSE: The goal of this study was to evaluate the utility of perfusion-weighted CT (PWCT) in predicting final infarct volume and clinical outcome in patients with acute middle cerebral artery (MCA) stroke. METHODS: Twenty-two consecutive patients with MCA stem occlusion who underwent intra-arterial thrombolysis within 6 hours of stroke onset had noncontrast CT and CT angiography with whole-brain PWCT imaging before treatment. Infarct volumes were computed from the initial PWCT and follow-up scans; clinical outcome was measured with the modified Rankin scale. RESULTS: Initial PWCT lesion volumes correlated significantly with final infarct volume (P=0.0002) and clinical outcome (P=0.01). For the 10 patients with complete recanalization, the relationship between initial and final lesion volume was especially strong (R(2)=0.94, P<0.0001, slope of regression line=0.92). For those without complete recanalization, there was progression of lesion volume on follow-up imaging (R(2)=0.50, P=0.01, slope of regression line=1.61). All patients with either initial PWCT lesion volumes >100 mL or no recanalization had poor outcomes (Rankin scores, 4 to 6). Mean admission NIH Stroke Scale scores and mean lesion volumes in the poor outcome group were significantly different compared with the good or fair outcome (Rankin scores, 0 to 3) group (21+/-4 versus 17+/-5, P=0.05, and 106+/-79 versus 29+/-37 mL, P=0.01). Patients with initial volumes <100 mL and partial or complete recanalization all had good (Rankin scores, 0 to 2) or fair (Rankin score, 3) outcomes. CONCLUSIONS: Lesion volumes on admission PWCT images approximate final infarct volume for patients with early complete recanalization of MCA stem occlusion. For those without complete recanalization, there is subsequent enlargement of lesion volume on follow-up. Initial PWCT lesion volumes also have predictive value; volumes >100 mL are associated with a poor clinical outcome. In these highly selected patients, initial PWCT lesion volume was a stronger predictor of clinical outcome than was initial NIH Stroke Scale score.

Acute Disease↗
PubMed2001

Silent thromboembolic events associated with the treatment of unruptured cerebral aneurysms by use of Guglielmi detachable coils: prospective study applying diffusion-weighted imaging.

BACKGROUND AND PURPOSE: Aneurysm embolization using Guglielmi detachable coils (GDC) is gaining increasing acceptance as a viable alternative to surgery in the treatment of cerebral aneurysms. Although recent reports describe a significant rate of symptomatic thromboembolic complications with GDC use, many of the neurologic deficits are transient. We sought to determine the incidence of silent thromboembolic events with the use of diffusion-weighted imaging and to correlate radiologic findings with the results of neurologic examinations. METHODS: Diffusion-weighted MR imaging was performed within 48 hours in 14 consecutive elective GDC aneurysm treatments. Embolizations were performed under systemic heparinization; all flush solutions were heparinized, and both guiding catheters and microcatheters were placed for continuous heparinized infusions. Neurologic examination, including the National Institutes of Health Stroke Scale determination, was performed by a stroke neurologist before the coiling procedures were performed, immediately after the procedures were performed, and before discharge. MR imaging examinations were reviewed by a stroke neurologist and an interventional neuroradiologist, with determination and characterization of diffusion-weighted imaging abnormalities. RESULTS: Small areas of restricted diffusion, presumed to represent procedure-related embolic infarctions, were noted on the images of eight of 14 patients. All except one of the areas were located ipsilateral to the side of the catheterization. Six patients had evidence of multiple infarcts. Most lesions were small (<2 mm); one patient with coil stretch and herniation into the parent vessel had numerous infarcts with a dominant posterior frontal infarct. Pre- and posttreatment National Institutes of Health Stroke Scale scores were unchanged for 13 of 14 patients. Overall, the rate of asymptomatic emboli was 61% (eight of 13 treatments) in uncomplicated treatments. Strokes occurred independently of the number of coils used; the mean number of coils used for patients with strokes was 7.6 (range, two to 13) and for patients without evidence of infarcts was 10.2 (range, one to 30). This was not a significant difference (P > .5). CONCLUSION: Silent thromboembolic events related to the use of the GDC system are a common occurrence, despite meticulous technique and systemic anticoagulation. Although clinical sequelae are rare, the high rate of occurrence suggests that alterations in the technique, such as the addition of antiplatelet agents, should be considered.

Adult↗
PubMed2000

Receptor binding and G-protein activation by new Met5-enkephalin-Arg6-Phe7 derived peptides.

Met5-enkephalin-Arg6-Phe7 (Tyr-Gly-Gly-Phe-Met-Arg-Phe, MERF) is a naturally occurring heptapeptide that binds to opioid and non-opioid recognition sites in the central nervous system. Four synthetic analogs with single or double amino acid substitutions were prepared by solid phase peptide synthesis to achieve proteolytically more stable structures: Tyr-D-Ala-Gly-Phe-Met-Arg-Phe (I), Tyr-D-Ala-Gly-Phe-D-Nle-Arg-Phe (II), Tyr-D-Ala-Gly-Phe-L-Nle-Arg-Phe (III) and Tyr-Gly-Gly-Phe-L-Nle-Arg-Phe (IV). In this study receptor binding characteristics and G-protein activation of MERF and its derivatives were compared in crude membrane fractions of frog and rat brain. Synthetic MERF-derived peptides were potent competitors for [3H]MERF and [3H]naloxone binding sites with the exception of analog (II) which turned to be substantially less active. The presence of 100 mM NaCl or 100 microM 5'-guanylylimidodiphosphate, Gpp(NH)p, decreased the affinity of the peptides in [3H]naloxone binding assays, suggesting that these ligands might act as agonists at the opioid receptors. Some of the compounds were also used to stimulate guanosine-5'-O-(3-[gamma-[35S]thio)triphosphate ([35S]GTPgammaS) binding in rat and frog brain membranes at concentrations of 10(-9)-10(-5) M. The EC50 values of analog (II) were the highest in both tissues. Analog (I) was as effective as MERF in rat brain membranes, but showed lower maximal stimulation in frog brain preparation. Again, analog (II) seemed to be the least efficacious peptide that stimulated [35S]GTPgammaS binding only by 59%. Specificity of the peptides was further investigated by the inhibition of agonist-stimulated [35S]GTPgammaS binding in the presence of selective antagonists for the opioid receptor types. The mu-selective antagonist cyprodime displayed the lowest potency in inhibiting the effects of the peptides, whereas norbinaltorphimine (kappa-selective antagonist) and naltrindole (delta-selective antagonist) were quite potent in both tissues. We concluded that MERF and its derivatives are able to activate G-proteins mainly via kappa- and delta-opioid receptors.

Animals↗
PubMed2000

Serological evidence of adenovirus infection in cats.

The widespread presence of adenoviruses in various species makes it probable that infection and the carrier state also exist in cats. On the basis of these considerations, investigations were carried out to find antibodies against adenovirus in sera from different cat populations kept under different conditions. For the antibody detection, purified adenovirus was used in an indirect ELISA. To produce positive serum, SPF cats were immunized with a purified hexon preparation. Altogether 632 field sera of different origin were tested. Among field samples, adenovirus seropositivity varied between 10-26%.

Adenoviridae Infections↗
PubMed2000

Use of isoptin for counteracting the effect of methol on cardiac activity in experimental animals.

The purpose of the present study is to use isoptin in order to lower intracellular Ca2+ concentration for counteracting the effect of methol on cardiac activity in acute intoxication of the experimental animals. Adult male Wistar rats were used - 8 animals/lot anaesthesized with urethan. ECG activity was recorded every 15 minutes, for 360 minutes. Administration (oral) of methol in a dose of 310 mg/kg/bw. (DL100) produced sinusal bradycardia, which became more marked later on. Isoptin administration in a dose of 5 mg/kg/bw. in rats with 310 mg/kg/bw. methol decreased the heart rate, the lowest value occurring 120 minutes after administration, followed by a slow increase until the end of the recording. When isoptin was given in a dose of 2.5 mg/kg/bw. to rats with 310 mg/kg/bw. methol, the decrease of the heart rate was much slower than before, for a period of 255 minutes, followed by a slight increase until the end of the recording. Isoptin counteracts the bradycardia - producing effect of methol in rats during the study time (6 hours), and the effect after this period of time requires further investigations.

Aminophenols↗
PubMed1999

Prostate cancer expression profiling by cDNA sequencing analysis.

Prostate cancer is a frequently diagnosed solid tumor that is originated mostly from prostate epithelium. One of the key issues in prostate cancer research is to develop molecular markers that can effectively detect and distinguish the progression and malignancy of prostate tumors. Automated, single-pass cDNA sequencing was utilized to rapidly identify expressed genes in a number of cDNA libraries constructed from various normal and tumor prostatic tissues. These included cell lines as well as short-term epithelial culture. A total of 6604 expressed sequence tags (ESTs) were generated and searched against on-line nucleotide and protein databases. A relational database centric software system was constructed to process, store, and analyze EST data rapidly. cDNA contigs were also obtained by assembly of multiple EST sequences. Protein structural signatures were annotated using motif analysis tools including BLOCKS and an in-house-designed neural network. Cross-library comparisons revealed their unique gene expression profiles. Several differentially expressed cDNA clones were identified, and their expression patterns were confirmed by RNA dot blot and RT-PCR analyses.

Cell Line↗
PubMed1999

Nociceptin binding sites in frog (Rana esculenta) brain membranes.

The recently discovered natural heptadecapeptide nociceptin (orphanin FQ) shares some homology with the opioid peptides but it binds to a distinct receptor type, termed nociceptin receptor. This study demonstrates the presence of specific nociceptin recognition sites in brain membrane fractions of an amphibian, Rana esculenta. Para-iodo-Phe(1)-nociceptin-amide was radiolabelled by catalytic dehalotritiation, resulting in p[(3)H]Phe(1)-nociceptin-amide of 25 Ci/mmol specific radioactivity. Specific binding of [(3)H]nociceptin-amide to frog brain membranes was found to be saturable and of high affinity with equilibrium K(d) values in the low nanomolar range. A single set of binding sites with about 180 fmol/mg protein maximal binding capacity was obtained in saturation and competition experiments. [(3)H]Nociceptin-amide binding could easily be inhibited by synthetic nociceptin compounds but not by opioid ligands. Both sodium ions and 5'-guanylylimidodiphosphate decreased the binding of the radioligand by transferring the receptor to a lower affinity state. Nociceptin dose-dependently stimulated the binding of the nonhydrolysable, radiolabeled GTP-analogue guanosine-5'-O-(3-thio)triphosphate ([(35)S]GTPgammaS) to G-proteins in frog brain membranes. Addition of 1 microM naloxone caused no significant change in the curves, indicating that nociceptin-mediated activation of G-proteins occurred through nonopioid mechanism.

Amides↗
PubMed1999

Characterization of [3H]Met-enkephalin-Arg6-Phe7 binding to multiple sites in rat and guinea pig cerebellum.

[3H]Met-enkephalin-Arg6-Phe7 (MERF) has been shown to label opioid (kappa2 and delta) and sigma2 sites in rat and frog brain membrane preparations, and no specific binding to kappa1 opioid receptors could be established (refs. 6 and 8). In this study the binding was examined in rat cerebellar membranes which are relatively rich in kappa2-sites, and in guinea pig cerebellar preparations where kappa1 opioid receptors are almost exclusively present. In accordance with our previous results, [3H]MERF binding could not be displaced in guinea pig cerebellar membranes neither with U-69,593 nor with naloxone or levorphanol suggesting no interaction with opioid sites, nevertheless a Kd of 2.8 nM was calculated in cold saturation experiments. In rat cerebellar membrane fractions about the half of the specific [3H]MERF binding sites was inhibited by opiate alkaloids such as naloxone, ethylketocyclazocine, or bremazocine. This portion of the heptapeptide binding sites was stereoselective as demonstrated by the difference in the affinities of the enantiomeric compounds levorphanol and dextrorphan, therefore it would represent an opioid site. In both tissues (-)N-allyl-normetazocine (SKF-10,047), which is also considered as sigma2 ligand, displayed the highest affinities. Among opioid peptides beta-endorphin and dynorphin(1-13) showed the highest potencies, displacing [3H]MERF also from its non-opioid sites. It was concluded therefore that [3H]MERF does not bind to kappa1 sites, and besides kappa2-opioid sites substantial binding to peptide preferring non-opioid sites, and/or sigma2 receptors also occurs.

Animals↗
PubMed1999

Long-lasting antinociceptive effect of DAMGO chloromethyl ketone in rats.

Previously, the opioid peptide Tyr-D-Ala-Gly-(NMe)Phe-CH2Cl (DAMCK) has been shown to bind irreversibly to mu opioid receptors in vitro. In the present work, the antinociceptive effect of DAMCK has been evaluated. Rats treated systemically with DAMCK (1-100 pg/kg) displayed a dose-dependent increase in tail-flick analgesia that peaked by 15 min, then stayed about the same until 60 min, followed by some decrease over time. Higher doses of DAMCK (10 ng/kg-100 microg/kg) produced a near-maximal antinociceptive effect that remained stable for 4 h. Significant antinociception was still detected 8 h, but not 24 h postinjection. In comparison, the parent peptide DAMGO (Tyr-D-Ala-Gly-(NMe)Phe-Gly-ol) reached maximal effect by about 30 min, followed by a rapid cessation of its antinociceptive response. Naloxone administered before DAMCK antagonized the antinociceptive response of DAMCK, indicating that it was mediated via opioid receptors. Naloxone administered 45 min after DAMCK attenuated the tail-flick response to some extent, but a substantial part (40-60% depending on the peptide concentration and evaluation time) remained unaffected. Central administration of DAMCK also elicited time- and concentration-dependent, profound, opioid receptor mediated, apparently irreversible antinociception.

Amino Acid Chloromethyl Ketones↗
PubMed1999

Acute stroke: improved nonenhanced CT detection--benefits of soft-copy interpretation by using variable window width and center level settings.

PURPOSE: To assess the use of nonstandard, variable window width and level review settings in computed tomography (CT) without contrast material administration in the detection of acute stroke. MATERIALS AND METHODS: Nonenhanced CT was performed in 21 patients with acute (< 6 hours) middle cerebral arterial stroke and nine control patients. Two blinded neuroradiologists rated all scans for presence of parenchymal hypoattenuation. Images were reviewed at a picture archiving and communication system (PACS) workstation, with standard, locally determined center level and window width settings of 20 and 80 HU and with variable soft-copy settings initially centered at a level of 32 HU with a width of 8 HU. Reviewers altered settings to accentuate gray and white matter contrast. RESULTS: With standard viewing parameters, sensitivity and specificity for stroke detection were 57% and 100%. Sensitivity increased to 71% with variable window width and center level settings, without loss of specificity. Receiver operating characteristic analysis revealed a significant improvement in accuracy with nonstandard, soft-copy review settings (P = .03, one-tailed z test). CONCLUSION: In nonehanced CT of the head, detection of ischemic brain parenchyma is facilitated by soft-copy review with variable window width and center level settings to accentuate the contrast between normal and edematous tissue.

Acute Disease↗
PubMed1999

Detection of adenovirus hexon sequence in a cat by polymerase chain reaction (short communication).

Adenoviral nucleic acid was detected by polymerase chain reaction (PCR) in pharyngeal and rectal swab samples of a cat seropositive for adenovirus and suffering from transient hepatic failure. The samples were taken at a one-year interval, and both faecal samples as well as the second pharyngeal sample were positive in PCR performed with general adenovirus primers. The size of the amplified products corresponded to that of the positive control. The identity of the amplicons was also confirmed by DNA sequencing. The 301 bp long hexon gene fragment was very similar to but distinguishable from the corresponding hexon sequence of human adenovirus type 2. This result suggests the possibility of persistent carrier status and shedding of adenovirus in cats.

Adenoviridae↗