The prospects for the diagnosis of bacterial meningitis]

The samples of spinal fluid arriving to the Clinical Infectious Hospital in 1994-1996 with the clinical diagnosis "generalized form of meningococcal infection" or "purulent meningitis of unclear etiology" were studied. The etiological agent was bacteriologically identified in 35% of 487 patients (in 25% of cases Neisseria meningitidis, in 7% of cases Streptococcus pneumoniae and in 2% of cases Haemophilus influenzae, type b, were detected). The method of latex agglutination, used in this study, was highly specific (100%) and moderately sensitive (67%); this method made it possible to diagnose 25% of cases additionally (N. meningitidis in 15% of cases, S. pneumoniae in 5% of cases and H. influenzae in 3% of cases). Diagnostics with the use of PCR was characterized by high specificity (> 97%) and sensitivity (> 85%) relatively to the "golden standard" of microbiological diagnostics. There were few false positive results (3 samples), caused probably by contamination at the moment of taking the samples. For this reason the results obtained by PCR could be used for diagnostic purposes even in cases of negative results given by other methods. Tests with the use of PCR made it possible to diagnose 29% more cases additionally (in 26% of cases N. meningitidis DNA and in 3% of cases S. pneumoniae DNA were detected. Thus the complex of methods used in this study permitted the detection of the etiological agent altogether in 87% of cases.     

Leukemia inhibitory factor (LIF) improves and prolongs the development of parthenogenetic mouse embryos

We studied the effect of the growth factor LIF on the development of parthenogenetic mouse embryos (CBA x C57BL/6)F1. LIF was added to the culture medium at 10, 50, 100, and 250 ng/ml at the morula stage and parthenogenetic embryos were cultivated in vitro until the late blastocysts stage and then transplanted in the uterus of pseudopregnant females, which were then sacrificed on day 12 of pregnancy. All the LIF doses used improved the development of parthenogenetic mouse embryos at the preimplantation stages and increased the amount of blastocysts by 16%, on average, as compared to the control. LIF at 50 and 100 ng/ml increased approximately twice the number of embryos that reached the somatic stages. Some of them reached the stage of 32-45 somites and had fore and hind limb buds. No such embryos were found in the control. Well formed placenta was observed in 6% of the embryos treated with LIF and the most pronounced effect was recorded at 100 ng/ml. The data we obtained suggest that exogenous LIF can improve pre- and postimplantation development of parthenogenetic mouse embryos due, possibly, to increased survival rate of embryonic stem cells derived from the inner cell mass of blastocysts. LIF improves not only the development of the parthenogenetic embryo per se, but also the formation of its extraembryonic envelopes, which leads to the development of a larger placenta in LIF-treated parthenogenetic embryos, as compared to the control.     

Selective retrograde transsynaptic transfer of a protein, tetanus toxin, subsequent to its retrograde axonal transport

The fate of tetanus toxin (mol wt 150,000) subsequent to its retrograde axonal transport in peripheral sympathetic neurons of the rat was studied by both electron microscope autoradiography and cytochemistry using toxin-horseradish peroxidase (HRP) coupling products, and compared to that of nerve growth factor (NGF), cholera toxin, and the lectins wheat germ agglutinin (WGA), phytohaemagglutinin (PHA), and ricin. All these macromolecules are taken up by adrenergic nerve terminals and transported retrogradely in a selective, highly efficient manner. This selective uptake and transport is a consequence of the binding of these macromolecules to specific receptive sites on the nerve terminal membrane. All these ligands are transported in the axons within smooth vesicles, cisternae, and tubules. In the cell bodies these membrane compartments fuse and most of the transported macromolecules are finally incorporated into lysosomes. The cell nuclei, the parallel golgi cisternae, and the extracellular space always remain unlabeled. In case the tetanus toxin, however, a substantial fraction of the labeled material appears in presynaptic cholinergic nerve terminals which innervate the labeled ganglion cells. In these terminals tetanus toxin-HRP is localized in 500-1,000 A diam vesicles. In contrast, such a retrograde transsynaptic transfer is not at all or only very rarely detectable after retrograde transport of cholera toxin, NGF, WGA, PHA, or ricin. An atoxic fragment of the tetanus toxin, which contains the ganglioside-binding site, behaves like intact toxin. With all these macromolecules, the extracellular space and the glial cells in the ganglion remain unlabeled. We conclude that the selectivity of this transsynaptic transfer of tetanus toxin is due to a selective release of the toxin from the postsynaptic dendrites. This release is immediately followed by an uptake into the presynaptic terminals.     

Influence of Contrast and Coherence on the Temporal Dynamics of Binocular Motion Rivalry

Levelt’s four propositions (L1–L4), which characterize the relation between changes in “stimulus strength” in the two eyes and percept alternations, are considered benchmark for binocular rivalry models. It was recently demonstrated that adaptation mutual-inhibition models of binocular rivalry capture L4 only in a limited range of input strengths, predicting an increase rather than a decrease in dominance durations with increasing stimulus strength for weak stimuli. This observation challenges the validity of those models, but possibly L4 itself is invalid. So far, L1–L4 have been tested mainly by varying the contrast of static stimuli, but since binocular rivalry breaks down at low contrasts, it has been difficult to study L4. To circumvent this problem, and to test if the recent revision of L2 has more general validity, we studied changes in binocular rivalry evoked by manipulating coherence of oppositely-moving random-dot stimuli in the two eyes, and compared them against the effects of stimulus contrast. Thirteen human observers participated. Both contrast and coherence manipulations in one eye produced robust changes in both eyes; dominance durations of the eye receiving the stronger stimulus increased while those of the other eye decreased, albeit less steeply. This is inconsistent with L2 but supports its revision. When coherence was augmented in both eyes simultaneously, dominance durations first increased at low coherence, and then decreased for further increases in coherence. The same held true for the alternation periods. The initial increase in dominance durations was absent in the contrast experiments, but with coherence manipulations, rivalry could be tested at much lower stimulus strengths. Thus, we found that L4, like L2, is only valid in a limited range of stimulus strengths. Outside that range, the opposite is true. Apparent discrepancies between contrast and coherence experiments could be fully reconciled with adaptation mutual-inhibition models using a simple input transfer-function.     

TGFalpha reactivates imprinted Igf2 in the parthenogenetic mice embryos and placenta

Imprinted genes play important roles in the mammalian development. In the parthenogenetic embryos (PE) there is only expression of maternally expressed genes. Therefore, PEs are appropriate experimental models to study genomic imprinting controlling mechanisms. The maternally expressed H19 and paternally expressed Igf2 are reciprocally imprinted genes in normal embryos. Here we studied effect of transforming growth factor alpha (TGFalpha) treatment in vitro (10 ng/ml at the morula stage) on the expression of Igf2/H19 locus in mice PE (9.5-days of gestation, 25 somites) and their placentas (PP). Using RT-PCR we showed that TGFalpha reactivated maternally imprinted Igf2 gene in parthenogenetic embryos and placentas. In spite of similar Tgfalpha expression in the pre-implantation stages, its expression in the 9.5-day parthenogenetic embryos is significantly less than in normal embryos (NE). In our experiments it was shown that reactivation of Igf2 gene occurred independently of H19 gene. In vitro TGFalpha treatment of mouse PE reactivated paternally expressed Igf2 gene in the PE and PP. In the PE and PP both Igf2 and H19 were expressed. It seems that TGFalpha can play an important role as modulator of the Igf2/H19 locus.     

Activation of δ-opioid receptors increases resistance of isolated heart to ischemia/reperfusion: The role of cAMP and intracellular calcium

Activation of cardiac -opioid receptors (ORs) by their selective agonist DPDPE (154 nM) increased the resistance of perfused rat heart to ischemia/reperfusion injury. Decreased release of creatine phosphokinase to the perfusate and decreased incidence of arrhythmias were observed during reoxygenation. At the same time, opioidergic decrease in left ventricular developed pressure took place both during the preischemic period and after restoring the coronary circulation. All these effects could be prevented by blocking -ORs by naltrindole or inhibition of Ca²⁺-ATPase of sarcoplasmic reticulum by cyclopiazonic acid. -OR agonist DPDPE had no effect on cAMP levels in myocardial tissue during the whole experiment. The obtained data suggest that the antiarrhythmic and cytoprotective effects observed after -OR stimulation can be realized through the changes in Ca²⁺ transport at the level of the sarcoplasmic reticulumTranslated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 55–62.Original Russian Text Copyright © 2005 by Lishmanov, Maslov, Lasukova, Platonov, Oeltgen.     

Effects of growth factors FGF4, TGFα, and TGFβ1 on development of parthenogenetic embryos of C57BL/6 mice

We studied the effects of three growth factors, fibroblast growth factor (FGF4), transforming growth factor (TGF), and transforming growth factor 1 (TGF1), on development of diploid parthenogenetic embryos of C57BL/6 mice, which are not capable of developing to somatic stages. Parthenogenetic embryos were treated with growth factors at optimal doses in vitro at the morula-blastocyst stages and transplanted in the uterus of pseudopregnant females. FGF4 and TGF improved the development of parthenogenetic embryos at the preimplantation stages and the number of blastocysts increased under the influence of TGF. All three growth factors improved the implantation of embryos in the uterus. When FGF4 or TGF1 2.4 were added to the nutrient medium, 2.4 or 1.6%, respectively, of parthenogenetic embryos reached the somatic stages in utero. No somitic embryos were observed in the control. The treatment of parthenogenetic embryos with two growth factors, FGF4 and TGF1 , simultaneously increased the amount of somatic embryos to 7.5%, while combination of three growth factors in creased the amount of such embryos to 16.7%. In the latter case, some parthenogenetic embryos reached the stage of 25–27 pairs of somites and were 2.0–2.5 mm long. The data we obtained suggest that, when combined, the growth factors FGF4, TGF, and TGF1 possessed a synergistic effect leading to a significant improvement of the development of parthenogenetic C57BL/6 embryos.__________Translated from Ontogenez, Vol. 36, No. 2, 2005, pp. 145–150.Original Russian Text Copyright © 2005 by Penkov, Platonov, Dimitrov, Mironova, Konyukhov.     

Effects of fibroblast growth factor 2 and insulin-like growth factor II on the development of parthenogenetic mouse embryos in vitro

Most parthenogenetic embryos (PEs) in mammals die shortly after implantation, and this failure to develop is associated with genomic imprinting. We have examined the influence of human recombinant basic fibroblast growth factor 2 (FGF-2) and human recombinant insulin-like growth factor II (ICF-II) on the development of (CBA x C57BL/6)F1 parthenogenetic mouse embryos. Embryos were treated in vitro at the morula stage with different doses of FGF-2 and, after their development to blastocysts, transferred to pseudopregnant recipients. The optimal doses of FGF-2 did not affect the number of forming and implanting blastocysts, but increased, from 20 to 42%, the number of embryos developing to somite stages. PEs (18-21 somites) treated with an optimal dose of FGF-2 were explanted for further development in culture by treatment with the second growth factor, IGF-II. Eighty-three percent of those embryos cultured with IGF-II (2.5 microg/ml) developed to 35 or more somites, as compared with 36% of embryos cultured without any growth factors (P < 0.01). Also, a significantly higher proportion of PEs developed to 40-50 somites in this case. These results show that the in vitro treatment of PEs with FGF-2 at the morula stage increases the number of somite embryos, and the second treatment of somite PEs with IGF-II in culture medium prolongs their development significantly.     

Crystallin synthesis in the lens of newborn mice]

Lenses of newborn mice were incubated for different time in the Hanks solution containing 14C-amino acids mixture. Syntheses of gamma-crystallin and subunits of alpha-crystallin were shown to start at the first minute of the incybation. The incorporation rate of 14C-amino acids into gamma-crystallin was twice as high as that into alpha-crystallin within 5 minutes of the incubation. The assembly of alpha-crystallin tetramers took place after 5 minutes from the beginning of the incubation. Preincubation with actinomycin D for 3 and 6 hours resulted in the decrease of 14C-amino acids incorporation into gamma-crystallin only. These data suggest that the synthesis of gamma-crystallin takes place on both short-lived and long-lived mRNAs. Alpha-Crystallin subunits are supposed to synthesize only on long-lived mRNAs.     

Electrical activity of the motor units of the muscles in blood supply disorders of the latter]

Electrical activity of the motor units in the muscles (m. gastrocnemius and m. extensor hallucis brevis) in normal humans and in the patients with impaired peripheral circulation in the lower limbs was studied with the needle concentric electrodes. A reduction in the muscle action potentials under conditions of their circulation impairment was revealed; this pointed to the myogenic origin of alterations in the skeletal muscles due to the incompetence of their blood circulation.