Experimental data on the life-cycle of Petasiger grandivesicularis Ishii, 1935 (Trematoda: Echinostomatidae)

Larval stages of an echinostome were found in Planorbis planorbis in a brackish water lake on the Black Sea coast of Bulgaria. The cercaria is a large-tailed form with 19 collar spines. The life-cycle was completed in the laboratory using aquarium-reared fishes (Lebistes reticulatus, Puntius tetrazona tetrazona, P. pentazona pentazona, P. nigrofasciatus, Carassius auratus auratus and Xiphophorus helleri) as second intermediate hosts and canaries as definitive hosts. The redia, cercaria, metacercaria and experimentally reared adults are described. The species is determined as Petasiger grandivesicularis Ishii, 1935, and its cercaria is compared in detail with those of related forms. A key to the known large-tailed echinostome cercariae from the Palaearctic Region is presented.     

Experimentally produced diploid-triploid mouse chimaeras develop up to adulthood

Spontaneous diploid-triploid chimaeras occur sporadically in various mammalian species including man, but so far have never been produced experimentally. In order to get a deeper insight into the developmental consequences of this anomaly, we have developed two procedures that enabled for the first time to produce routinely diploid-triploid embryos, foetuses, and animals in the mouse. These procedures are: (1) aggregation of cleaving diploid embryos with triploid embryos produced by suppression of the second polar body in zygotes, and (2) fusion of a haploid karyoplast with one blastomere of the two-cell diploid embryos. The first procedure yielded 23 living and 6 dead postimplantation embryos and foetuses (age: 8th-19th day) out of which 22 were chimaeric. In addition, three chimaeric neonates reached adulthood. Two animals were fertile, and one--an overt chimaera--was an infertile male. The rate of postimplantation development of aggregation chimaeras was normal or only slightly retarded, and with one exception the foetuses were morphologically normal. Generally, the highest contribution of the 3n component in extra-embryonic structures was noted in the yolk sac, and usually it was higher than its contribution to the organs of the body. Chimaerism was most often noted in the liver, the heart, the intestine, and the lungs. Participation of triploid cells to all tissues studied, both in the body and in extra-embryonic structures, appeared to decrease slightly as development progressed. The second procedure yielded 10 foetuses and 6 adults. Three foetuses were chimaeric. Six fertile adults were probably non-chimaeras: the triploid component was absent in the coat and in the blood.     

Microsomal triglyceride transfer protein expression in mouse intestine

Immunohistochemical and biochemical approaches were utilized to compare the expression of microsomal triglyceride transfer protein (MTP) and cellular retinol binding protein II (CRBPII) with the expression of apolipoprotein (apo)B and apoA-I along the entire length of the small intestine in mice. MTP is expressed in villus-associated enterocytes along the length of the small intestine. Maximal expression occurs within the first 20% of the intestine and decreases to less than 3% of maximum in the distal third of the intestine. The expression of CRBPII is nearly identical with that of MTP. Peak expression of apoB and apoA-I occurs in the first 25% of the intestine; however, expression in the most distal segments of the intestine is 10%–15% of maximum expression. In mice fed a Western diet for 3 weeks the expression of MTP and CRBPII was elevated in the distal regions of the intestine, whereas the expression patterns for apoB and apoA-I were similar to those found in mice on control diets. We conclude that the patterns of expression, as well as the regulation of MTP and CRBPII, are similar. However, the expression and regulation of these two proteins differ from those of apoB and apoA-I. In particular, the expression of MTP is not coordinated with the expression of apoB, even though the two proteins are essential for the assembly and secretion of chylomicrons.     

Potential application of stem cells in urogynecology

Recent advances in stem cells therapy and tissue engineering techniques hold great promise for recovery of external urethral sphincter proper functioning and urinary incontinent patients treatment. Adult stem cells (ASCs) may be derived from striated muscles, fat tissue or as mesenchymal cells from bone marrow. These cells can differentiate in functionally normal smooth or striated muscle cells. ASCs injected to external urethral sphincter or bladder neck cause the increase in urethral closure pressure. Favourable findings of trials in animal models and in vitro encouraged to first trials in humans and hold a promising future for the treatment of urinary incontinence.     

Differential scanning microcalorimetry study of the thermal denaturation of haemoglobin

A study of thermal denaturation of human haemoglobin A0 (HbA0) and methaemoglobin (mHb) was carried out by differential scanning calorimetry. DSC haemoglobin profiles were scan rate dependent and only partly reversible. Thermal unfolding of protein was analysed with the use of both equilibrium thermodynamic and kinetic approaches. The fittings based on the simple equilibrium/dissociation model were good and much more satisfactory than those based on "fully-kinetic" models. However the presence of some kinetic distortion during the unfolding process should be noted due to the scan-rate effect on DSC transitions. The calculated first-order kinetic constant for mHb was higher by two orders than the one for HbA0 (stabilised form). The average activation energy for HbA0 was found to be 289 +/- 28 kJ M-1 while for mHb it was about 100 kj M-1 lower.     

Tetanic crisis and antiepileptic drugs. A case report

OBJECTIVE AND METHODS: We presented a rare case of tetanic crisis in a 23-year old mentally retarded woman with epilepsy after treatment by oxcarbazepine, the new anticonvulsant agent. We reviewed laboratory, radiographic and medical examinations and recommend a proper treatment in such cases. RESULTS AND CONCLUSION: The laboratory tests revealed only severe hypocalcemia. We described the potential role of oxcarbazepine in the induction of activity of cytochrome P 450 system of hepar and increases of less active metabolism of vitamin D. Supplementation of vitamin D and calcium in patients taking antiepileptic drugs is in the same case crucial.     

Mining parasite data using genetic programming

Genetic programming is a technique that can be used to tackle the hugely demanding data-processing problems encountered in the natural sciences. Application of genetic programming to a problem using parasites as biological tags demonstrates its potential for developing explanatory models using data that are both complex and noisy.     

Abeta40-Lactam(D23/K28) models a conformation highly favorable for nucleation of amyloid

Recent solid-state NMR data (1) demonstrate that Abeta(1)(-)(40) adopts a conformation in amyloid fibrils with two in-register, parallel beta-sheets, connected by a bend structure encompassing residues D(23)VGSNKG(29), with a close contact between the side chains of Asp23 and Lys28. We hypothesized that forming this bend structure might be rate-limiting in fibril formation, as indicated by the lag period typically observed in the kinetics of Abeta(1)(-)(40) fibrillogenesis. We synthesized Abeta(1)(-)(40)-Lactam(D23/K28), a congener Abeta(1)(-)(40) peptide that contains a lactam bridge between the side chains of Asp23 and Lys28. Abeta(1)(-)(40)-Lactam(D23/K28) forms fibrils similar to those formed by Abeta(1)(-)(40). The kinetics of fibrillogenesis, however, occur without the typical lag period, and at a rate approximately 1000-fold greater than is seen with Abeta(1)(-)(40) fibrillogenesis. The strong tendency toward self-association is also shown by size exclusion chromatography in which Abeta(1)(-)(40)-Lactam(D23/K28) forms oligomers even at concentrations of approximately 1-5 microM. Under the same conditions, Abeta(1)(-)(40) shows no detectable oligomers by size exclusion chromatography. Our data suggest that Abeta(1)(-)(40)-Lactam(D23/K28) could bypass an unfavorable folding step in fibrillogenesis, because the lactam linkage "preforms" a bendlike structure in the peptide. Consistent with this view Abeta(1)(-)(40) growth is efficiently nucleated by Abeta(1)(-)(40)-Lactam(D23/K28) fibril seeds.     

Differential contribution of plasmalemmal Na/Ca exchange isoforms to sodium-dependent calcium influx and NMDA excitotoxicity in depolarized neurons

Inhibition of Na(+),K(+)-ATPase during NMDA applications greatly increased NMDA-induced excitotoxicity in primary cultures of forebrain neurons (FNs), but not in cerebellar granule cells (CGCs). Because Na(+),K(+)-ATPase inhibition promotes reversal of plasmalemmal Na(+)/Ca(2+) exchangers, we compared the activities of reversed K(+)-independent (NCX) and K(+)-dependent (NCKX) Na(+)/Ca(2+) exchangers in these cultures. To this end, we measured gramicidin-induced and Na(+)-dependent elevation in cytosolic [Ca(2+)] ([Ca(2+)](c)) that represents Ca(2+) influx via reversed NCX and NCKX; NCX activity was dissected out by removing external K(+). The [Ca(2+)](c) elevations mediated by NCX alone, and NCX plus NCKX combined, were 17 and 6 times more rapid in FNs than in CGCs, respectively. Northern blot analysis showed that FNs preferentially express NCX1 whereas CGCs expressed NCX3. Differences in expression of other isoforms (NCX2, NCKX2, NCKX3 and NCKX4) were less pronounced. We tested whether the NCX or NCKX family of exchangers contributes most to the toxic NMDA-induced Ca(2+) influx in depolarized neurons. We found that in FNs, inhibition of NCX alone was sufficient to significantly limit NMDA excitotoxicity, whereas in CGCs, inhibition of both NCX and NCKX was required. The data suggest that the high activity of NCX isoforms expressed in FNs, possibly NCX1, sensitizes these neurons to NMDA excitotoxicity.     

Preliminary studies of phthalocyanine sensitizers incorporated into human leukemia cells from two cell-lines

Three phthalocyanine dyes-sensitizers were incorporated into two types of human T leukemia cells from two cell-lines: CCRF and MOLT 4. The efficiency of the dye incorporation into cells and photochemical properties of stained cells were investigated using fluorescence spectroscopy. The dyes exhibited different properties in each of the two cell-lines. Small differences in cell membrane properties have a strong influence on the efficiency of dye incorporation and on the course of photodynamic reaction. It is suggested that, for a given patient, an optimal dye-sensitizer should be established before photodynamic treatment.