Changes in local blood flow in the solitary kidney after chronic blockade of cholinergic mediation

The method of hydrogen clearance has been used to study the influence of compensatory hypertrophy and continuous 120-day pharmacologic blockade of parasympathetic nerves by atropine on interorgan peritubular blood circulation of the Wistar line rat kidneys. Reliable "lagging" of the cortical blood flow behind the analogous values of the control group with a single kidney is noted. Decrease of the cortex perfusion under conditions of cholinergic blockade is due to "baring" of the high sympathogenic tonus of cortical vessels in spite of postnephrectomic hyperperfusion in the control. A conclusion is made concerning significance of cholinergic mediation in development of compensatory hypertrophy of a single kidney in syndrome of its denervation impairment.     

Different genetic requirements for repair of replication-born double-strand breaks by sister-chromatid recombination and break-induced replication

Homologous recombination (HR) is the major mechanism used to repair double-strand breaks (DSBs) that result from replication, but a study of repair of DSBs specifically induced during S-phase is lacking. Using an inverted-repeat assay in which a DSB is generated by the encountering of the replication fork with nicks, we can physically detect repair by sister-chromatid recombination (SCR) and intra-chromatid break-induced replication (IC-BIR). As expected, both events depend on Rad52, but, in contrast to previous data, both require Rad59, suggesting a prominent role of Rad59 in repair of replication-born DSBs. In the absence of Rad51, SCR is severely affected while IC-BIR increases, a phenotype that is also observed in the absence of Rad54 but not of its paralog Rdh54/Tid1. These data are consistent with SCR occurring by Rad51-dependent mechanisms assisted by Rad54, and indicate that in the absence of strand exchange-dependent SCR, breaks can be channeled to IC-BIR, which works efficiently in the absence of Rad51. Our study provides molecular evidence for inversions between repeats occurring by BIR followed by single-strand annealing (SSA) in the absence of strand exchange.     

Molecular analysis of sister chromatid recombination in mammalian cells

Sister chromatid recombination (SCR) is a potentially error-free pathway for the repair of double-strand breaks arising during replication and is thought to be important for the prevention of genomic instability and cancer. Analysis of sister chromatid recombination at a molecular level has been limited by the difficulty of selecting specifically for these events. To overcome this, we have developed a novel "nested intron" reporter that allows the positive selection in mammalian cells of "long tract" gene conversion events arising between sister chromatids. We show that these events arise spontaneously in cycling cells and are strongly induced by a site-specific double-strand break (DSB) caused by the restriction endonuclease, I-SceI. Notably, some I-SceI-induced sister chromatid recombination events entailed multiple rounds of gene amplification within the reporter, with the generation of a concatemer of amplified gene segments. Thus, there is an intimate relationship between sister chromatid recombination control and certain types of gene amplification. Dysregulated sister chromatid recombination may contribute to cancer progression, in part, by promoting gene amplification.     

Novel genetic tools facilitate the study of cortical neuron migration

Key facets of mammalian forebrain cortical development include the radial migration of projection neurons and subsequent cellular differentiation into layer-specific subtypes. Inappropriate regulation of these processes can lead to a number of congenital brain defects in both mouse and human, including lissencephaly and intellectual disability. The genes regulating these processes are still not all identified, suggesting genetic analyses will continue to be a powerful tool in mechanistically studying the development of the cerebral cortex. Reelin is a molecule which we have understood to be critical for proper cortical development for many years. The precise mechanism of Reelin, however, is not fully understood. To address both of these unresolved issues, we report here the creation of a novel conditional allele of the Reelin gene and showcase the use of an Etv1-GFP transgenic line highlighting a subpopulation of the cortex: layer V pyramidal neurons. Together, these represent genetic tools which may facilitate the study of cortical development in a number of different ways.     

Role of the hypothalamus in organizing the wakefulness-primary sleep cycle in the frog Rana temporaria

New data are presented on the role of the hypothalamus in re-arrangement of tonus of the vegetative nervous system during three forms of rest of the primary sleep in the frog. Temporal organization of the cycle " awakefulness -primary sleep" depends on interaction of the anterior and posterior hypothalamus. The anterior hypothalamus is responsible for manifestation of two forms of rest of the primary sleep, i.e. diurnal resting form (P-1) which is associated with the increase in plastic tone of skeletal muscles, and the other resting form (P-3) which is associated with the decrease in muscle tonus. These forms of rest are accompanied by the predominance of parasympathetic tonus of the vegetative nervous system. The posterior hypothalamus is associated with manifestation of the resting form which includes the increase in the rigidity of muscle tonus (P-2) and transient phasic increase in the heart rate, the latter being observed at all forms of the primary sleep. Statistical treatment of the ECG revealed specific pattern of two-dimensional density of distribution of probabilities of R-R intervals for the resting forms of the primary sleep which is important for identification of different phases in the " awakefulness -primary sleep" cycle in vertebrates.     

Ryanodine receptor dysfunction and triggered activity in the heart

Arrhythmogenesis has been increasingly linked to cardiac ryanodine receptor (RyR) dysfunction. However, the mechanistic relationship between abnormal RyR function and arrhythmogenesis in the heart is not clear. We hypothesize that, under abnormal RyR conditions, triggered activity will be caused by spontaneous calcium release (SCR) events that depend on transmural heterogeneities of calcium handling. We performed high-resolution optical mapping of intracellular calcium and transmembrane potential in the canine left ventricular wedge preparation (n = 28). Rapid pacing was used to initiate triggered activity under normal and abnormal RyR conditions induced by FKBP12.6 dissociation and beta-adrenergic stimulation (20-150 microM rapamycin, 0.2 microM isoproterenol). Under abnormal RyR conditions, almost all preparations experienced SCRs and triggered activity, in contrast to control, rapamycin, or isoproterenol conditions alone. Furthermore, under abnormal RyR conditions, complex arrhythmias (monomorphic and polymorphic tachycardia) were commonly observed. After washout of rapamycin and isoproterenol, no triggered activity was observed. Surprisingly, triggered activity and SCRs occurred preferentially near the epicardium but not the endocardium (P < 0.01). Interestingly, the occurrence of triggered activity and SCR events could not be explained by cytoplasmic calcium levels, but rather by fast calcium reuptake kinetics. These data suggest that, under abnormal RyR conditions, triggered activity is caused by multiple SCR events that depend on the faster calcium reuptake kinetics near the epicardium. Furthermore, multiple regions of SCR may be a mechanism for multifocal arrhythmias associated with RyR dysfunction.     

ROOT CONTRACTION IN FREESIA (IRIDACEAE)

The contractile roots of the horticultural variety Freesia hybrida Bailey (Iridaceae) were determined to contract via a growth/collapse mechanism. Contraction is initiated by a radial growth of middle and outer cortical parenchyma cells which is morphologically evident by an expanded diameter of the root. No concomitant decrease in length of the actively growing cells was observed. Shortening of the root is caused by axial tension produced by the radial growth of cells contiguous with nonexpanded cells distally. Centripetal collapse of expanded cells, coupled with passive shortening of inner cortical parenchyma and stelar tissues, releases axial tension slowly, returning the shortened root to equilibrium. Inner cortical parenchyma cells shorten in an accordion-like manner facilitated by partial dissolution of middle lamellar material.     

Event-related synchronization and desynchronization of EEG during perception of emotional stimuli: association with autonomous nervous system activity

Up to now, mechanisms of neurovisceral integration are not clear. The main objective of the present investigation consisted in studying cortical concomitants of sympathetic activity during emotional perception. The 62-channel EEG and skin conductance response (SCR) were recorded while right-handed healthy participants (n-33) viewed sequentially presented neutral, pleasant, and unpleasant pictures. The event-related synchronization (ERS) and desynchronization were measured in different frequency bands. Relying on median split of SCR amplitudes elicited by the presented stimuli the participants were segregated into groups with low (SCR-) and high (SCR+) autonomous activity. In was revealed that group differences were associated with power changes in the low (4-6 Hz) theta band only. For both groups in the early test period (up to 1 s after stimulus onset), emotional vs. neutral stimuli induced larger theta-ERS over posterior cortical regions with greater impact on the right parieto-temporo-occipital regions. At the later phases (2-6 s after stimulus onset), only the SCR group retained emotion-related greater right hemisphere synchronization. It is concluded that the right parieto-temporo-occipital cortex mediates mechanisms of motivated attention and sympathetic activation.     

"Spontaneous" complete remissions in chronic lymphocytic leukemia: report of three cases and review of the literature

"Spontaneous" complete remissions (SCR) are a rare event in chronic lymphocytic leukemia (CLL). In this article, we report three cases of SCR observed in a series of 285 patients followed at a single institution during the last 15 years. SCR was documented by clinical and hematologic data, including bone marrow biopsy, and immune cell markers. A delay of 0.9-1.6 years between "clinical" and "clonal" remission was observed. A review of other cases of SCR in CLL is also performed.     

Effect of pentobarbital,chloralose, and urethane on inhibitory postsynaptic potentials of cortical neurons

The effect of pentobarbital, chloralose, and urethane on IPSPs arising in auditory cortical neurons in response to electrical stimulation of geniculocortical fibers was studied in experiments on cats immobilized with D-tubocurarine. Pentobarbital (60–80 mg/kg body weight, intraperitoneally) sharply reduced the number of neurons responding by spikes to geniculocortical stimulation. Only short-latency responses remained. The number of neurons responding with IPSPs was unchanged. Pentobarbital increased the duration of the IPSPs by 1.5–2 times and shortened their latent periods. Under the influence of chloralose (60 mg/kg, intraperitoneally) the number of responses of EPSP—spike—IPSP type was increased and the duration of the IPSPs also was increased by 3–4 times. The latent period of the primary IPSPs was shortened. Unlike pentobarbital and chloralose, urethane (1000 mg/kg, intravenously) reduced the duration of the IPSPs to 30 msec. About 2% of IPSPs recorded before anesthesia had a latent period of 1.0–1.5 msec. Under the influence of anesthesia the relative number of these IPSPs increased to 5.7%. It it postulated that they are monosynaptic. The mechanism of action of general anesthetics on the cortical inhibitory system is discussed.     

Conditional tonic stimulus control of nonspecific arousal

Subjects performed a reaction time (RT) task in the presence of colored indirect lighting which had previously been associated with either sporadic electric shock (Unsafe context) or no shock (Safe context). Autonomic and cortical processes were influenced by the visual context in two ways. Nonspecific arousal was elevated in the Unsafe context as compared with the Safe context (larger SCR and more accelerative HR change elicited by the RT warning stimulus, and retarded habituation of the middle component of the slow cortical potential during the warning stimulus). In addition, information processing may have been impaired in the Unsafe as compared to the Safe context, since the earliest component of the SCR and the N100 component of the auditory evoked potential were both reduced. Higher frequency of unelicited SCR was observed following changes from a Safe to an Unsafe context than with reverse changes, during the association of these contexts with shock, but this was the only evidence of direct tonic conditioning. In general, the results demonstrate the degree to which psychophysiological processes may be influenced by tonic environmental conditions.     

Direct and indirect roles of cytochrome b in the mediation of superoxide generation and NO catabolism by mitochondrial succinate-cytochrome c reductase

Mitochondrial superoxide (O2*-) production is an important mediator of oxidative cellular injury. Succinate-cytochrome c reductase (SCR) of the electron transport chain has been implicated as an essential part of the mediation of O2*- generation and an alternative target of nitric oxide (NO) in the regulation of mitochondrial respiration. The Q cycle mechanism plays a central role in controlling both events. In the present work, O2*- generation by SCR was measured with the EPR spin-trapping technique using DEPMPO (5-diethoxylphosphoryl-5-methyl-1-pyrroline N-oxide) as the spin trap. In the presence of succinate, O2*- generation from SCR was detected as the spin adduct DEPMPO/*OOH. Inhibitors of the Q(o*-) site only marginally reduced (20-30%) this O2*- production, suggesting a secondary role of Q(o*-) in the mediation of O2*- generation. Addition of cyanide significantly decreased (approximately 70%) O2*- production, indicating the involvement of the heme component. UV-visible spectral analysis revealed that oxidation of ferrocytochrome b was accompanied by cytochrome c(1) reduction, and the reaction was mediated by the formation of an O2*- intermediate, indicating a direct role for cytochrome b in O2*- generation. In the presence of NO, DEPMPO/*OOH production was progressively diminished, implying that NO interacted with SCR or trapped the O2*-. The consumption of NO by SCR was investigated by electrochemical detection using an NO electrode. In the presence of succinate, SCR-mediated NO consumption was observed and inhibited by the addition of superoxide dismutase, suggesting the involvement of O2*-. Under the conditions of argon saturation, the NO consumption rate was not enhanced by succinate, suggesting a direct role for O2*- in the mediation of NO consumption. In the presence of succinate, oxidation of the ferrocytochrome b moiety of SCR was accelerated by the addition of NO, and was inhibited by argon saturation, indicating an indirect role for cytochrome b in the mediation of NO consumption.     

Characteristics of thermograms of the skin of the anterior surface of the trunk in persons with various tonus of the sympathetic and parasympathetic nervous system

Vegetative regulation is shown to affect the heat pattern of the trunk skin. Two types of thermograms are found in men: "monotonous" and "spotted", the first thermogram being characterized by prevalence of the parasympathetic and the second one-by sympathetic tonus. In women "spotted" thermograms and sympathicotonic direction of the vegetative regulation are registered.     

Regulation of somatic cell reprogramming through inducible mir-302 expression

Global demethylation is required for early zygote development to establish stem cell pluripotency, yet our findings reiterate this epigenetic reprogramming event in somatic cells through ectopic introduction of mir-302 function. Here, we report that induced mir-302 expression beyond 1.3-fold of the concentration in human embryonic stem (hES) H1 and H9 cells led to reprogramming of human hair follicle cells (hHFCs) to induced pluripotent stem (iPS) cells. This reprogramming mechanism functioned through mir-302-targeted co-suppression of four epigenetic regulators, AOF2 (also known as KDM1 or LSD1), AOF1, MECP1-p66 and MECP2. Silencing AOF2 also caused DNMT1 deficiency and further enhanced global demethylation during somatic cell reprogramming (SCR) of hHFCs. Re-supplementing AOF2 in iPS cells disrupted such global demethylation and induced cell differentiation. Given that both hES and iPS cells highly express mir-302, our findings suggest a novel link between zygotic reprogramming and SCR, providing a regulatory mechanism responsible for global demethylation in both events. As the mechanism of conventional iPS cell induction methods remains largely unknown, understanding this microRNA (miRNA)-mediated SCR mechanism may shed light on the improvements of iPS cell generation.     

A fast algorithm for estimating transmission probabilities in QTL detection designs with dense maps

Background

In the case of an autosomal locus, four transmission events from the parents to progeny are possible, specified by the grand parental origin of the alleles inherited by this individual. Computing the probabilities of these transmission events is essential to perform QTL detection methods.

Results

A fast algorithm for the estimation of these probabilities conditional to parental phases has been developed. It is adapted to classical QTL detection designs applied to outbred populations, in particular to designs composed of half and/or full sib families. It assumes the absence of interference.

Conclusion

The theory is fully developed and an example is given.     

Excess no predisposes mitochondrial succinate-cytochrome c reductase to produce hydroxyl radical

Mitochondria-derived oxygen-free radical(s) are important mediators of oxidative cellular injury. It is widely hypothesized that excess NO enhances O(2)(?-) generated by mitochondria under certain pathological conditions. In the mitochondrial electron transport chain, succinate-cytochrome c reductase (SCR) catalyzes the electron transfer reaction from succinate to cytochrome c. To gain the insights into the molecular mechanism of how NO overproduction may mediate the oxygen-free radical generation by SCR, we employed isolated SCR, cardiac myoblast H9c2, and endothelial cells to study the interaction of NO with SCR in vitro and ex vivo. Under the conditions of enzyme turnover in the presence of NO donor (DEANO), SCR gained pro-oxidant function for generating hydroxyl radical as detected by EPR spin trapping using DEPMPO. The EPR signal associated with DEPMPO/(?)OH adduct was nearly completely abolished in the presence of catalase or an iron chelator and partially inhibited by SOD, suggesting the involvement of the iron-H(2)O(2)-dependent Fenton reaction or O(2)(?-)-dependent Haber-Weiss mechanism. Direct EPR measurement of SCR at 77K indicated the formation of a nonheme iron-NO complex, implying that electron leakage to molecular oxygen was enhanced at the FAD cofactor, and that excess NO predisposed SCR to produce (?)OH. In H9c2 cells, SCR-dependent oxygen-free radical generation was stimulated by NO released from DEANO or produced by the cells following exposure to hypoxia/reoxygenation. With shear exposure that led to overproduction of NO by the endothelium, SCR-mediated oxygen-free radical production was also detected in cultured vascular endothelial cells.     

POM-POM2/cellulose synthase interacting1 is essential for the functional association of cellulose synthase and microtubules in Arabidopsis

In plants, regulation of cellulose synthesis is fundamental for morphogenesis and plant growth. Cellulose is synthesized at the plasma membrane, and the orientation of synthesis is guided by cortical microtubules; however, the guiding mechanism is currently unknown. We show that the conditional root elongation pom2 mutants are impaired in cell elongation, fertility, and microtubule-related functions. Map-based cloning of the POM-POM2 locus revealed that it is allelic to CELLULOSE SYNTHASE INTERACTING1 (CSI1). Fluorescently tagged POM2/CSI1s associated with both plasma membrane-located cellulose synthases (CESAs) and post-Golgi CESA-containing compartments. Interestingly, while CESA insertions coincided with cortical microtubules in the pom2/csi1 mutants, the microtubule-defined movement of the CESAs was significantly reduced in the mutant. We propose that POM2/CSI1 provides a scaffold between the CESAs and cortical microtubules that guide cellulose synthesis.     

Mechanism of effect of sympathetic nervous system on skin receptors

While researching the mechanism underlying the effect of the sympathetic nervous system on the operation of skin receptors, we demonstrated that a tremendous role in this process is played by smooth muscles, whose condition also mediates the sympathetic effect on receptors. The increase in the activity of the sympathetic nerve fibers results in an increase in the tonus of the smooth muscles which in turn alters the mechanical condition of the tissues surrounding the receptors. It was established that the change in the tonus of the smooth muscles in the skin itself affects the reaction of the receptors that is evoked by mechanical stimulation. The change in the tonus of the smooth muscles of the vessels affects the response of receptors caused by cooling of the skin.Nizhegorod Medical Institute, Russian Federation Ministry of Health. Translated from Neirofiziologiya, Vol. 24, No. 5, pp. 552–558, September–October, 1992.