The application of cross-point switch arrays as input selector switch devices for multi-channel electrophysiological experiments

Integrated circuits (ICs) containing cross-point switch arrays were applied to create analog input selector switch devices for multi-channel electrophysiological experiments. The described analog input selector switch devices make it possible to connect to the main amplifier's inputs those microelectrode and preamplifier output wires that yield unit discharges of acceptable shape and amplitude, or yield other kind of acceptable electrophysiological signals (EEG, EP). This kind of selector allows to use higher number of preamplifier channels and to ignore the input channels without adequate signals or the channels with noisy inputs. No manual switching is required, as the work is done by computer controlled switches. The switch positions can be saved and reloaded at the next experimental session through an I/O port (e.g. the parallel port) of the computer.

Concomitant accumulation of intracellular free calcium and arachidonic acid in the ischemic-reperfused rat heart

This study was designed to elucidate the relationship between enhanced cytoplasmic calcium levels (Ca2+i) and membrane phospholipid degradation, a key step in the loss of cellular integrity during cardiac ischemia/reperfusion-induced damage. Isolated rat hearts were subjected to 15 min ischemia followed by 30 min reperfusion. Ca2+i was estimated by the Indo-1 fluorescence ratio technique. Degradation of membrane phospholipids as indicated by the increase of tissue arachidonic acid content was assessed in tissue samples taken from the myocardium at various points of the ischemia/reperfusion period. The hemodynamic parameters showed almost complete recovery during reperfusion. Fluorescence ratio increased significantly during ischemia, but showed a considerable heart-to-heart variation during reperfusion. Based upon the type of change of fluorescence ratio during reperfusion, the hearts were allotted to two separate subgroups. Normalization of fluorescence ratio was associated with low post-ischemic arachidonic acid levels. In contrast, elevated fluorescence ratio coincided with enhanced arachidonic acid levels. This observation is suggestive for a relationship between the Ca2+-related fluorescence ratio and arachidonic acid accumulation probably due to a calcium-mediated stimulation of phospholipase A2.

Identification and structural analysis of synthetic oligosaccharides of Shigella sonnei using MALDI-TOF MS

MALDI-TOF mass spectroscopy was used for the molecular weight determination of protected synthetic oligosaccharides related to a cell surface bacterial polysaccharide. By-products containing chlorinated protecting groups caused isotopic patterns characteristic of the natural isotopic distribution of chlorine, were identified on the basis of isotopic distribution. 2,4,6-Trihydroxyacetophenone (THAP) as a matrix was better than 2,5-dihydroxybenzoic acid (DHB) for compounds containing chlorine, since monoisotopic resolution and no fragmentation were observed. In the post source decay (PSD) mode the identification of the oligosaccharide sequence through cleavage of the interglycosidic linkages was also possible, thus providing a sensitive and accurate tool for the structural verification of synthetic oligosaccharide intermediates.

Path finding by tube morphogenesis in an amoeboid organism

We have studied how the plasmodium of Physarum polycephalum, a large amoeboid cell, is able to track the shortest path between two selected points in a labyrinth. When nutrients are supplied at these points to a sheet-like plasmodium extended fully in a maze, the organism forms a single tube which connects the two sites via the shortest route. During the path finding, plasmodial parts in dead ends of the maze shrink and finally the tube with the minimum-length is selected from the existing possibilities. A simple cellular mechanism based on interacting cellular rhythms may describe the experimental observations.

Renal injury in perinatal hypoxia: ultrasonography and changes in renal function

We studied 12 hypoxaemic neonates (5 mature newborns, birth weight 2850-4200 g, gestational age 37-41 weeks; and 7 premature newborns, birth weight 770-1850 g, gestational age 27-34 weeks;) with repeated urine and blood chemistry on the 1st and 3rd days of life. Nephrosonographical examinations on the 1st, 3rd and 5-7th days of life were also performed. As controls, 12 healthy infants were examined (gestational age 36-42 weeks; birth weight 24504200 g). Hypoxic neonates had higher serum creatinine and blood urea nitrogen levels. Tubular markers also demonstrated renal tubular damage. Neonates in both hypoxic groups were hyperuricaemic and hyperuricosuric, and had higher urinary protein concentrations. All these infants exhibited an increased echogenicity of the renal cortex, and 11/12 showed the same finding in the medullary area. These findings disappeared within 1 week in all infants. Among the 12 healthy control infants, no cortical hyperechogenicity was found and only three of these infants displayed transient medullary renal hyperechogenicity.

CONCLUSION

Since the hypoxaemic infants demonstrated greatly increased urinary concentrations of uric acid and protein, we suggest that a temporary precipitation of these two agents may be responsible for the ultrasonographic findings. Circulatory redistribution might play a role in the phenomenon of cortical hyperechogenicity.

A screen for genes required for meiosis and spore formation based on whole-genome expression

BACKGROUND

Meiosis is the process by which gametes are generated with half the ploidy of somatic cells. This reduction is achieved by three major differences in chromosome behavior during meiosis as compared to mitosis: the production of chiasmata by recombination, the protection of centromere-proximal sister chromatid cohesion, and the monoorientation of sister kinetochores during meiosis I. Mistakes in any of these processes lead to chromosome missegregation.

RESULTS

To identify genes involved in meiotic chromosome behavior in Saccharomyces cerevisiae, we deleted 301 open reading frames (ORFs) which are preferentially expressed in meiotic cells according to microarray gene expression data. To facilitate the detection of chromosome missegregation mutants, chromosome V of the parental strain was marked by GFP. Thirty-three ORFs were required for the formation of wild-type asci, eight of which were needed for proper chromosome segregation. One of these (MAM1) is essential for the monoorientation of sister kinetochores during meiosis I. Two genes (MND1 and MND2) are implicated in the recombination process and another two (SMA1 and SMA2) in prospore membrane formation.

CONCLUSIONS

Reverse genetics using gene expression data is an effective method for identifying new genes involved in specific cellular processes.

Effect of beta-carotene and nucleotide base supplementation on blood composition and immune response in weaned pigs

The effect of synthetic beta-carotene and synthetic nucleotide base on daily weight gain, feed consumption and certain haematological, biochemical and immunological parameters of piglets were studied in a 3-week experiment. Beginning one week prior to weaning, the diet fed to one experimental group of piglets was supplemented with 10% Rovimix Beta-carotene at 875 mg/kg of diet. Synthetic uracil and adenine (98%, Sigma-Aldrich) were mixed into the diet of the other experimental group at doses of 500 mg/kg of diet for each substance. The control group received the basic diet without any supplementation. The changes observed over time in the haematological parameters and in certain biochemical variables could be regarded as physiological. By day 21 of the experiment, beta-carotene supplementation had significantly lowered the neutrophilic granulocyte percentage and elevated the lymphocyte percentage, while in the other two groups a change of opposite tendency occurred. At the end of the experimental period there was a decrease in plasma vitamin E concentration due to carotene supplementation (control: 6.1 +/- 1.5, nucleotide: 6.3 +/- 2.5, carotene: 2.3 +/- 1.5 mg/L). Lymphocyte blastogenesis induced by phytohaemagglutinin and concanavalin A increased by 50 and 130%, respectively, in the nucleotide group and by 60 and 30%, respectively, in the carotene group, while it did not change in the control group. The supplements exerted no positive effect on the in vivo cellular immune response.

[Qualitative and quantitative detection of hepatitis C virus RNA by PCR technique. Monitoring of viral copies after liver transplantation]

The authors demonstrate the HCV nucleic acid amplification method is not wide-spread in Hungary yet. The HCV-RNA is usually detectable 2-4 weeks after infection independently the immunostate of the patients. The authors help to select the adequate measurement(s) in logical order when HCV infection is suspected. The benefit of the PCR method is emphasized. Monitoring of the HCV-RNA titer of the liver transplanted patients promotes to establish the fluctuation of HCV-RNA copies and the effectivity of therapy following transplantation. The detection of HCV-RNA by PCR method is a proof of an acute or chronic infection and rules out past infection. The quantitative PCR measurement is useful for determination of indication and control of efficacy of antiviral therapy.

[Processing vestibular impulses in the central nervous system. Study based on positron emission tomography]

BACKGROUND AND OBJECTIVE

Functional imaging methods have opened new perspectives for vestibular research. Many authors have investigated the central connections of the system, but the differences between the reports leave further questions open. We investigated the cerebral projection of the vestibular system, using positron emission tomography in right-handed subjects.

PATIENTS AND METHODS

Bilateral caloric stimulation was used in every volunteer (n = 6). This can be considered a standard method, which will make it possible to compare the results from different laboratories in the future. A detailed map of activated and deactivated brain regions is included.

RESULTS

Changes caused by vestibular stimulation are portrayed. The activated regions partially correspond with previous results in the literature. We would like to point out the Brodmann 6 region as the cortical manifestation of involuntary isometric tightening of muscles. We have found many, previously unidentified regions showing decreased regional cerebral blood flow.

CONCLUSIONS

We are the first to point out the functional connection between the hippocampus and the vestibular system in this report.

[Rapid diagnostic method for detecting Down syndrome in newborns]

The authors analysed the applicability of FISH on buccal and peripheral blood smears to detect Down syndrome among newborn infants. 11 children with previous cytogenetic result and 15 neonates examined prospectively were included in the study. All FISH results were in accordance with the cytogenetic diagnosis. In the prospective group the status of Down syndrome was confirmed in 12 cases, while 3 neonates turned to be healthy. Based on their preliminary results the authors emphasize the technique is extremely useful for a quick diagnosis especially when using blood smears. The method described here can be of a great help when there is no access to classical cytogenetic analysis, or it might fail to give result. Sample preparation is easy, microscopic slides with the specimen can be transported via regular post to cytogenetic laboratories.

pH-sensitive inwardly rectifying chloride current in cultured rat cortical astrocytes

The effect of pH(o) on plasma membrane chloride current of cultured rat cortical astrocytes was investigated using the whole-cell patch-clamp technique. In the presence of intra- and extracellular solutions with symmetrical high Cl(-) content and K(+) channel inhibitors, the cells exhibited an inwardly rectifying current. The current activated slowly at potentials negative to -40 mV and did not display time-dependent inactivation. The current was inhibited by 0.1 mM Cd(2+), 0.1 mM Zn(2+), 1 mM 9-anthracene-carboxylic acid, and 0.2 mM 5-nitro-2-(3-phenylpropylamino)benzoic acid, but not by 10 mM Ba(2+) or 3 mM Cs(+). Reversal potential of the current followed the chloride equilibrium potential and was not influenced by changes in K(+) or Na(+) concentration. The inwardly rectifying chloride current was augmented by extracellular acidosis and reduced by alkalosis. The pH sensitivity was most pronounced in the physiologically relevant pH(o) range of 6.9--7.9. Lowering pH to 6.4 induced no additional increase in steady-state current amplitude compared with pH(o) 6.9, but it substantially slowed the activation kinetics. According to its kinetic and pharmacological properties this chloride current is similar to that found in cultured rat astrocytes after long-term treatment with dibutyryl-cAMP, however, in our cultures it was consistently expressed without any treatment with the drug. Considering that astrocytes possess carbonic anhydrase and Cl(-)/HCO3(-) antiporter, this current may participate in the regulation of the interstitial and astrocyte pH.

AZFc deletion detected in a newborn with prenatally diagnosed Yq deletion

A case of prenatally diagnosed Yq deletion is described. Fluorescence in situ hybridisation (FISH) was used to identify the abnormal chromosome and to exclude mosaicism. Based on the cytogenetic result and the ultrasound investigation the pregnancy was continued. A newborn with normal male genitalia was delivered. Microdeletion analysis of the Yq showed the absence of the AZFc region. This type of deletion has been described as being associated with azoospermia or oligozoospermia with a progressive decrease of sperm number over time. Long-term andrological follow-up of the newborn will be necessary with eventual cryoconservation of sperm at early adulthood. The present report proposes that AZF analysis combined with FISH has an important role in accurate genetic counselling in sex chromosome anomalies.

Preliminary communication: examination of the harmful effect to fetuses of fumonisin B(1) in pregnant sows

Three sows were fed a diet mixed with Fusarium moniliforme fungal culture from the 107th day of pregnancy until parturition. Fumonisin B(1) toxin was administered to two sows (sows 1 and 2) in a daily dose of 300 mg for an additional 7 days subsequent to parturition, i.e., for a total of 14-16 days. The third sow (No. 3) was given the toxin in the same daily dose only until parturition, i.e., for 7 days in total. There were no symptoms observed in any of the sows. Two piglets were taken from each of the three sows and sacrificed immediately after parturition, i.e., prior to the first suckling. After 24 h, two additional piglets were taken for slaughter from each of the litters, which by then had access to colostrum. Finally, on the 7th day postparturition another two piglets per litter were sacrificed and material obtained from them was processed for examination. It was established that fumonisin B(1) present in the Fusarium moniliforme culture resulted in damage to the fetuses in utero. Of the changes indicating toxic effect, intraalveolar, subpleural, and interstitial pulmonary edema of various degrees of severity could be detected in the piglets sacrificed immediately following parturition and before the first suckling. Pathological changes were observed in the histopathological sections of the liver, and increases in the activities of plasma aspartic acid transaminase (AST), gamma glutamyl transferase (GGT) and alkaline phosphatase (AKLP), higher than physiological levels were detected. The serum-free sphinganine/sphingosine ratio, considered a bioindicator of fumonisin B(1) toxicosis, varied in accordance with the degree of severity of the changes which occurred. The values obtained were found to be between 0.29 and 0.36 in the cases of severe pulmonary edema, and between 0.20 and 0.24 for the cases of mild pulmonary edema. In the piglets of the sows fed the toxin for an additional 7 days subsequent to parturition and which were born with severe pulmonary edema, mild pulmonary edema could be detected after colostrum suckling, 24 h, and 7 days after parturition. The SA/SO value of the serum in these two piglets was 0.19 and 0.20, while at the same time AST, GGT, and ALKP values higher than physiological levels were measured. In the milk samples taken from sows 1 and 2 and examined after 24 h and after 7 days FB(1) was detected in quantities of 18.0-27.5 ppb. There were no changes observed on the seventh day in the piglets of the third sow, the diet of which contained no toxin after parturition. However, as the piglets of the third sow demonstrated only mild effects of pulmonary edema it is not possible to establish with certainty a postpartum cause-effect relationship between fumonisin in colostrum and pulmonary edema.

Fluorescence in situ hybridization of chorionic interphase cells for prenatal screening of Down syndrome

OBJECTIVE

Our purpose was to determine the usefulness and reliability of fluorescence in situ hybridization on interphase chorionic villi cells in the prenatal diagnosis of Down syndrome.

METHODS

A total of 336 samples of chorionic villi were analysed by direct chromosome preparation and FISH with a DNA probe specific to chromosome 21. The samples were obtained as part of the routine obstetric investigation and management.

RESULTS

The sampling and direct karyotyping was successful in all cases. At least 50 cells were valuable by FISH in 331 of 336 samples. Both methods showed Down syndrome in 12 cases. The follow-up investigations showed that there was no false-negative or false-positive result following these procedures.

CONCLUSION

Based on these results and the fact that it is possible to analyse by interphase FISH at least ten times more cells than by conventional cytogenetic methods, and these cells originate from different tissues of chorionic villi, it is concluded that FISH increases the reliability of the diagnosis. Nevertheless, more data are needed for correct statistical analysis. Since this method is cheaper and gives diagnosis earlier than cell culture, the combination of direct chromosome preparation and FISH on chorionic villi is offered for prenatal Down syndrome screening.

[Investigation of the cerebral projection of the vestibular system using positron emission tomography]

The authors investigated the cerebral projection of the vestibular system, using positron emission tomography, in right-handed subjects. Both sided cold caloric stimulation was used in every volunteer (n = 6). A detailed map of activated and deactivated brain regions is included. This portrays changes caused by vestibular stimulation. The contralaterally activated regions according to the stimulation side were: postcentral gyrus, transvers temporal gyrus, superior temporal gyrus, posterior part of the insula, claustrum, putamen, inferior parietal lobule, precentral gyrus, premotor cortex, cingulate gyrus. The ipsilaterally activated regions were: transvers temporal gyrus, superior temporal gyrus, inferior parietal lobule, posterior part of the insula. There was no hemispherial dominance. The activated regions partially correspond with previous results in the literature. It would like to be pointed out the Brodmann 6 region as the cortical manifestation of involuntary isometric tightening of muscles. The contralaterally deactivated regions were: inferior, superior and medius temporal gyrus, medial and medius frontal gyrus, inferior occipital gyrus, parahippocampal gyrus and hippocampus. Ipsilaterally deactivated regions were: superior and medial frontal gyrus, inferior temporal gyrus, angular gyrus, parahippocampal gyrus and hippocampus, fusiform and inferior occipital gyrus. There was prominent hemispherial dominance in the stimulated, ipsilateral side. The deactivation based functional connection between the hippocampus and the vestibular system was pointed out in such a relation for the first time in this report.

Functional genomics identifies monopolin: a kinetochore protein required for segregation of homologs during meiosis i

The orderly reduction in chromosome number that occurs during meiosis depends on two aspects of chromosome behavior specific to the first meiotic division. These are the retention of cohesion between sister centromeres and their attachment to microtubules that extend to the same pole (monopolar attachment). By deleting genes that are upregulated during meiosis, we identified in Saccharomyces cerevisiae a kinetochore associated protein, Mam1 (Monopolin), which is essential for monopolar attachment. We also show that the meiosis-specific cohesin, Rec8, is essential for maintaining cohesion between sister centromeres but not for monopolar attachment. We conclude that monopolar attachment during meiosis I requires at least one meiosis-specific protein and is independent of the process that protects sister centromere cohesion.

[Familial occurrence of Turner syndrome]

The authors report a family in which a woman with the mosaic Turner karyotype 45,X/46,X,r(X) transmitted the ring (X) chromosome to the second daughter and transmitted the X-derived chromosome to the first daughter. The mother had normal fertility with three documented pregnancies and conceptions occurred without any hormonal therapy. Her first pregnancy ended with spontaneous abortion, while the second pregnancy resulted in a 45,X/46,X,+mar female with ovarian failure and the third pregnancy resulted in a 45,X/46,X,r(X) female. The nature of the ring chromosome was confirmed by conventional cytogenetic technics. A small marker chromosome was identified as an X-derived chromosome by fluorescent in situ hibridisation (FISH).

Phosphorylation of MYPT1 by protein kinase C attenuates interaction with PP1 catalytic subunit and the 20 kDa light chain of myosin

The effect of phosphorylation in the N-terminal region of myosin phosphatase target subunit 1 (MYPT1) on the interactions with protein phosphatase 1 catalytic subunit (PP1c) and with phosphorylated 20 kDa myosin light chain (P-MLC20) was studied. Protein kinase C (PKC) phosphorylated threonine-34 (1 mol/mol), the residue preceding the consensus PP1c-binding motif ((35)KVKF(38)) in MYPT1(1-38), but this did not affect binding of the peptide to PP1c. PKC incorporated 2 mol P(i) into MYPT1(1-296) suggesting a second site of phosphorylation within the ankyrin repeats (residues 40-296). This phosphorylation diminished the stimulatory effect of MYPT1(1-296) on the P-MLC20 phosphatase activity of PP1c. Binding of PP1c or P-MLC20 to phosphorylated MYPT1(1-296) was also attenuated. It is concluded that phosphorylation of MYPT1 by PKC may therefore result in altered dephosphorylation of myosin.

[Ethical aspects of prenatal screening for Down's syndrome]

Trisomy 21, the chromosomal base of Down's syndrome, results in severe mental and physical handicap. Owing to the development of medical genetics reliable screening and diagnostic procedures for the detection of the disorder are available in Hungary. To achieve the goals of prenatal screening it is important to address the main ethical issues arising through the application of technical-professional skills. The core objective of prenatal screening for Down's syndrome is to give information about the genetic condition of the fetus in order to enhance the autonomy of the parents in family planning. Screening programs should respect the ethical requirements of the principles of "do no harm", beneficence and autonomy of the patients, which are the most important ethical norms of doctor-patient relationship. Regarding the social aspects of screening it is essential to claim that voluntary participation and nondirective genetic counselling can exclude eugenic purposes. Though introduction of prenatal tests does not imply the discrimination of the disabled, anxiety of handicapped people deserves more attention. Abortion of affected fetuses isn't among the objectives of prenatal genetic screening but patient's autonomy is supported in decisions concerning the future of the pregnancy. Social justice can be taken into consideration by providing the test to all women without respect to their social position, educational level or their age. An open debate about the issues of prenatal screening for Down's syndrome could promote the formation of a consensus between professionals and the public.