Estimation of bacteriological spoilage of pork cutlets by electronic nose

The utility of chemosensor array (EN) signals of head-space volatiles of aerobically stored pork cutlets as a non-invasive technique for monitoring their microbiological load was studied during storage at 4, 8 and 12 degrees C, respectively. The bacteriological quality of the meat samples was determined by standard total aerobic plate counts (TAPC) and colony count of selectively estimated Pseudomonas (PS) spp., the predominant aerobic spoilage bacteria. Statistical analysis of the electronic nose measurements were principal component analysis (PCA), and canonical discriminant analysis (CDA). Partial least squares (PLS) regression was used to model correlation between microbial loads and EN signal responses, the degree of bacteriological spoilage, independently of the temperature of the refrigerated storage. Sensor selection techniques were applied to reduce the dimensionality and more robust calibration models were computed by determining few individual sensors having the smallest cross correlations and highest correlations with the reference data. Correlations between the predicted and "real" values were given on cross-validated data from both data reduced models and for full calibrations using the 23 sensor elements. At the same time, sensorial quality of the raw cutlets was noted subjectively on faultiness of the odour and colour, and drip formation of the samples. These preliminary studies indicated that the electronic nose technique has a potential to detect bacteriological spoilage earlier or at the same time as olfactory quality deterioration.     

Effect of Different Concentrations of Bacillus subtilis on Immune Response of Broiler Chickens

This trial was conducted to study the effects of different Bacillus subtilis concentrations on immune response of broiler chickens. There were 5 treatment groups: control, with no added B. subtilis supplementation, and 4 treatment groups receiving feed supplemented with different concentrations of B. subtilis. The trial was conducted with 225 broilers. The weight of broiler chickens in all groups receiving feed supplemented with B. subtilis was significantly higher and the feed conversion was better independently of the concentration than that of the control chickens. The degree of diffuse lymphohistiocytic infiltration and the number of solitary lymphoid follicles in the mucosa increased in accordance with the B. subtilis concentration of the feed. The birds from the groups fed B. subtilis-supplemented diets had significantly increased antibody responses to vaccination against Newcastle disease virus. The appearance of increased diffuse lymphohistiocytic infiltration and solitary lymphoid follicles in the mucosa and a stronger response to NDV indicate increased immunological response in chickens fed with a B. subtilis-supplemented diet.     

Subsequent effect of subacute T-2 toxicosis on spermatozoa, seminal plasma and testosterone production in rabbits

Pannon White (n=12) male rabbits (weight: 4050 to 4500 g, age: 9 months) received 2 ml of a suspension containing purified T-2 toxin by gavage for 3 days. The daily toxin intake was 4 mg/animal (0.78 to 0.99 mg/kg body weight (BW)). Control animals (n=12) received toxin-free suspension for 3 days. Since a feed-refusal effect was observed on the second day after T-2 administration, a group of bucks (n=10) were kept as controls (no toxin treatment) but on a restricted feeding schedule, that is, the same amount of feed was provided to them as was consumed by the exposed animals. On day 51 of the experiment (i.e. 48 days after the 3-day toxin treatment), semen was collected, and pH, concentration, motility and morphology of the spermatozoa, as well as concentration of citric acid, zinc and fructose in the seminal plasma, were measured. After gonadotropin-releasing hormone (GnRH) analogue treatment, the testosterone level was examined. One day of T-2 toxin treatment dramatically decreased voluntary feed intake (by 27% compared to control, P<0.05) and remained lower (P<0.05) during the first 2 weeks after the withdrawal of the toxin. BW of the contaminated rabbits decreased by 88% on days 17 and 29 compared to controls (P<0.05). No effect of toxin treatment was detected on pH and quantity of the semen or concentration of spermatozoa. The ratio of spermatozoa showing progressive forward motility decreased from 65% to 53% in the semen samples of toxin-treated animals compared to controls (P>0.05). The ratio of spermatozoa with abnormal morphology increased (P<0.05) in the ejaculates collected from the toxin-treated animals. T-2 toxin applied in high doses decreased the concentration of citric acid in seminal plasma (P<0.05). No effect of T-2 toxin on the concentrations of the other seminal plasma parameters (fructose and zinc) was observed. T-2 toxin decreased the basic testosterone level by 45% compared to control (P<0.01) and resulted in lower (P<0.05) GnRH-induced testosterone concentration. Feed restriction, that is, less nutrient intake, resulted in more morphologically abnormal spermatozoa in the semen, but it did not cause significant loss in BW, motility of the spermatozoa, composition of the seminal plasma or testosterone concentration--its effect needs further examination.     

Computational theories on the function of theta oscillations

Neural rhythms can be studied in terms of conditions for their generation, or in terms of their functional significance. The theta oscillation is a particularly prominent rhythm, reported to be present in many brain areas, and related to many important cognitive processes. The generating mechanisms of theta have extensively been studied and reviewed elsewhere; here we discuss ideas that have accumulated over the past decades on the computational roles it may subserve. Theories propose different aspects of theta oscillations as being relevant for their cognitive functions: limit cycle oscillations in neuronal firing rates, subthreshold membrane potential oscillations, periodic modulation of synaptic transmission and plasticity, and phase precession of hippocampal place cells. The relevant experimental data is briefly summarized in the light of these theories. Specific models proposing a function for theta in pattern recognition, memory, sequence learning and navigation are reviewed critically. Difficulties with testing and comparing alternative models are discussed, along with potentially important future research directions in the field.     

Transgenic rabbit production with simian immunodeficiency virus-derived lentiviral vector

Transgenic rabbit is the preferred disease model of atherosclerosis, lipoprotein metabolism and cardiovascular diseases since upon introducing genetic mutations of human genes, rabbit models reflect human physiological and pathological states more accurately than mouse models. Beyond that, transgenic rabbits are also used as bioreactors to produce pharmaceutical proteins in their milk. Since in the laboratory rabbit the conventional transgenesis has worked with the same low efficiency in the last twenty five years and truly pluripotent embryonic stem cells are not available to perform targeted mutagenesis, our aim was to adapt lentiviral transgenesis to this species. A simian immunodeficiency virus based replication defective lentiviral vector was used to create transgenic rabbit through perivitelline space injection of fertilized oocytes. The enhanced green fluorescent protein (GFP) gene was placed under the ubiquitous CAG promoter. Transgenic founder rabbits showed mosaic pattern of GFP expression. Transgene integration and expression was revealed in tissues derived from all three primary germ layers. Transgene expression was detected in the developing sperm cells and could get through the germ line without epigenetic silencing, albeit with very low frequency. Our data show for the first time, that lentiviral transgenesis could be a feasible and viable alternative method to create genetically modified laboratory rabbit.     

The effect of the CYP 2C19*2 polymorphism on stroke care

Clopidogrel is an inhibitor of platelet-aggregation used in the prevention of secondary stroke. The molecule is activated by the cytochrome P450 2C19 (CYP2C19) enzyme. The frequent CYP2C19*2 point mutation causes loss of enzyme function, a decreased (heterozygous form) or blocked (homozygous form) formation of the active molecule. Thus, for a patient harboring a mutated allele, clopidogrel does not provide effective protection against stroke. Multiple drugs inhibit the CYP2C19 enzyme and their simultaneous use with clopidogrel is especially hazardous for patients with genetically decreased enzyme activity. Frequency of the CYP2C19*2 is variable in different populations, highest rates were detected in some Asian groups. In our study the CYP2C19 genotype was determined in one Hungarian sample of 354 stroke patients and 221 healthy controls. Frequency of the minor allele was found to be 12.87% (12.85% in stroke patients, 12.89% in healthy controls). The proportion of the homozygous CYP2C19*2 variant causing total loss of gene function was 1.74%, rate of the heterozygous allele causing reduced enzyme activity was 22.26% in the total population. Our results for the allele frequencies of the CYP2C19*2 gene are similar to those found in other Caucasian populations. In conclusion, the homozygous mutation, causing ineffectiveness of clopidogrel is relatively rare. However, the heterozygous form in which interaction of CYP2C19 inhibitors causes further decrease in the genetically impaired enzyme activity is present in every fifth drug-taking patient. Based on our findings, we would like to emphasize that it is important to adjust individually antiplatelet treatment in ischemic stroke patients and to take into consideration genetic factors as well as drugs taken for comorbid conditions.     

Body mass and body fat in Hungarian schoolboys: differences between 1980-2005

The prevalence of juvenile excess weight keeps growing in the more developed world (WHO, 1998). The aim of the study was to compare the prevalence of overweight and obesity in Hungarian schoolboys in 1980 and 2005.Two independent representative data collections were performed in volunteer boys aged between 6.51 and 18.50 years in the same 90 settlements of the country in 1980 (n=13,061) and 2005 (n=13,060). Height, body mass, and five skinfolds were measured by the same investigators in both instances. Overweight and obesity were estimated by using BMI (Cole et al., 2000), respectively skinfold thicknesses (Parízková, 1961).The pair-wise differences between height means were consistently significant in the 12 age groups studied. Body mass differences were not exactly proportionate with height. The boys of 2005 had significantly more relative body fat than those of 1980. The prevalence of overweight and obesity was remarkably higher in 2005.Taller height and a part of the heavier body mass in 2005 was attributed to a positive secular growth trend. The increases in BMI and fat content are negative consequences of a markedly changed lifestyle associated with inactivity and dietary habits. Because of its public health importance the trends of childhood obesity should be closely monitored.     

Conservation of the drought-inducible DS2 genes and divergences from their ASR paralogues in solanaceous species.

The drought-inducible DS2 genes of potatoes are members of the ASR (abscisic acid, stress and ripening) gene family. Previously it was shown that expression of DS2 genes is highly dehydration-specific in potato leaves, is not inducible by cold, heat, salt, hypoxia or oxidative stresses, and is independent of abscisic acid (ABA). Now it is shown that StDS2 does not respond either to sucrose or any plant hormones. Conservation of DS2 genes with this unique mode of regulation was studied in the solanaceous species with different relationships to potatoes. DS2 orthologues were identified by DNA sequence alignment in the closely related Lycopersicon and Capsicum species but not in the more distantly related Nicotiana sp. DNA and RNA gel blot analysis revealed the presence of a gene highly homologous to the potato gene StDS2 in tomato (LeDS2) with the same desiccation-specific expression in leaves and organ-specific expression in flowers and green fruits. The LeDS2 promoter was isolated and found to be almost identical in sequence with the promoter of StDS2, except for a 45-bp insertion in tomato. In contrast, no gene highly similar to StDS2 was detected in Nicotiana species on DNA gel blots. Neither StDS2 nor LeDS2 promoter regions were able to confer expression for the beta-glucuronidase (GUS) reporter gene in transgenic tobacco plants indicating that the trans regulatory factors necessary for DS2 expression are not conserved either in Nicotiana tabacum. These data suggest a narrow species-specificity and late evolution of the DS2-type genes within the family Solanaceae.     

Nectar secretion dynamics of Hungarian local pear cultivars

 The dynamics of daily nectar secretion was studied in 28 local pear cultivars in a Hungarian cultivar collection and three main types were distinguished. 1. Cultivars secreting nectar continuously are the most favourable for pollinators, rewarding them both with nectar and pollen. 2. Cultivars with discontinuous nectar secretion have sufficient insect attraction only if anther dehiscence is continuous during the day. In the first two types nectar secretion peaks usually appeared at 9:00 or 10:00, 14:00 or 15:00 and 18:00 or 19:00, with 4–5-hour intervals. 3. In some cultivars no nectar secretion was observed in any or some of the studied years, these being the least attractive for pollinators. The cultivars studied did not necessarily show the same type of nectar secretion dynamics in each season. From the viewpoint of pollination it is also of high importance, in which developmental phase nectar secretion begins. Received August 27, 2002; accepted January 7, 2003 Published online: June 2, 2003     

Carbon-source assimilation pattern of the astaxanthin-producing yeast Phaffia rhodozyma

Eleven Phaffia rhodozyma strains were assayed for their ability to utilize 99 compounds as single carbon source. Some of them showed modified coloration compared to colonies of the same strain grown on glucose medium.