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PubMed1999

Multisite optical recording of excitability in the enteric nervous system.

A multisite optical recording technique consisting of an array of 464 photodiodes was used to measure dynamic changes in transmembrane potentials (Vm) of guinea-pig and mouse enteric neurones stained with the voltage-sensitive dye Di-8-ANEPPS. Optical recordings of Vm changes in enteric neurones which were evoked by depolarizing current pulses or synaptic activation mirrored the Vm changes measured intracellularly in the same neurone. Action potentials had fractional change in fluorescence of -0.09 +/- 0.06% and their peak to peak noise level was 20 +/- 14% of the action potential amplitude. Optical recordings after electrical stimulation of interganglionic nerve strands revealed slow EPSPs, nicotinergic supra- and subthreshold fast EPSPs as well as propagation of action potentials along interganglionic strands. Local application of acetylcholine onto a single ganglion induced reproducibly and dose dependently action potential discharge demonstrating the feasibility of neuropharmacological studies. The optical mapping made it possible to record action potentials simultaneously in a large number of neurones with high spatiotemporal resolution that is unattainable by conventional techniques. This technique presents a powerful tool to study excitability spread within enteric circuits and to assess differential activation of enteric populations in response to a number of stimuli which modulate neuronal activity directly or through synaptic mechanisms.

Acetylcholine↗
PubMed2002

Dynamic changes of status epilepticus-induced neuronal degeneration in the mediodorsal nucleus of the thalamus during postnatal development of the rat.

PURPOSE: Status epilepticus (SE) was previously found to induce damage in the mediodorsal nucleus of the thalamus (MD) in both adult and immature rats. This study was designed to describe age-related changes of SE-induced neuronal degeneration in this part of the brain. METHODS: SE was induced by LiCl/pilocarpine in five age groups of rats (P12-P25). Distribution of degenerating neurons was studied at various time intervals from 4 h up to 1 week using Fluoro Jade B (FJB) staining. For P12 and P25 rats, an interval of 3 months was added. RESULTS: Damaged neurons were found in all age groups during a 1-week period after SE. Patterns of neuronal degeneration, however, changed in an age-related manner. In animals at P12 and P15, FJB-labeled neurons were located in the central and lateral segment of the MD. In the P18 group, degenerating neurons occurred in all three segments of the MD, with a prevalence in central and lateral subdivisions. In contrast, in P21 and P25 rats, FJB-labeled neurons were predominantly located in the central and medial segments. Degenerating neurons were still present 3 months after SE in the medial segment in P25 animals, whereas no labeled neurons were detected in the P12 group at this time. CONCLUSIONS: Our data demonstrate that the pattern of neuronal degeneration in MD is mainly related to age at SE onset. In addition to damage occurring during the acute phase of SE, a population of degenerating neurons was detected in P25 animals during the chronic period 3 months after SE.

Aging↗
PubMed1988

On the occurrence of three-center hydrogen bonds in cyclodextrins in crystalline form and in aqueous solution: comparison of neutron diffraction and molecular dynamics results.

Three-center (bifurcated) hydrogen bonds may play a role by serving as an intermediate state between different dynamically changing hydrogen bonding patterns. Hydrogen bonding configurations can be studied experimentally by neutron diffraction and theoretically by computer simulation techniques. Here, both methods are used to analyse the occurrence of three-center hydrogen bonds in crystals of cyclodextrins. Almost all experimentally observed three-center hydrogen bonds in the crystal are reproduced in the molecular dynamics (MD) simulations, even as far as the detailed asymmetric geometry is concerned. On the basis of this result a MD simulation of cyclodextrin in aqueous solution is searched for the occurrence of three-center hydrogen bonds. Significant differences are found. In solution more different three-center hydrogen bonds per alpha-cyclodextrin molecule are observed than in the crystal but the population (existence as percent of the simulation period) of each three-center hydrogen bond is lower in solution than in crystal. These may indeed serve as intermediate states in the process of changing one hydrogen bonding pattern into another.

Chemical Phenomena↗
PubMed2001

Dynamic changes in the morphology of Cryptococcus neoformans during murine pulmonary infection.

The pathogenesis of Cryptococcus neoformans infection has been studied extensively with respect to inflammatory and pathological changes, but very little information is available regarding the morphology of yeast cells during the course of infection. Electron microscopy of Cryptococcus neoformans in murine pulmonary infection revealed increased cell wall thickness with time, but this difference was only partially accounted for by increases in cell diameter. Cell walls of melanized cells were thicker than those of nonmelanized cells 2 h after infection, and the cell wall of yeast became blacker with time, suggesting that melanization contributes to the increased cell wall thickness. Heterogeneous cell populations emerged, with the appearance of giant forms. While for C. neoformans ATCC strain 24067 (serotype D) the full spectrum of cell sizes were observed, for strains H99 (serotype A) and 3501 (serotype D) cells were divisible into two populations, giant and micro forms. In contrast to cellular heterogeneity, the epitope recognized by a protective mAb on the capsular glucuronoxylomannan (GXM) was found at all times of infection. Immunoelectron microscopy using mAbs to GXM demonstrated reactivity with intracellular structures, suggesting that synthesis of capsular polysaccharide occurs, at least in part, in the cytoplasm. In summary, the results indicate that: (i) the infection is dynamic with respect to yeast cell morphology; (ii) giant cell forms arise in tissue during the course of infection; (iii) cell walls blacken and thicken during the course of infection, consistent with melanin synthesis during infection; and (iv) GXM epitopes are found in the capsule, cell wall and cytoplasm, consistent with intracellular polysaccharide synthesis. The results indicate that the population of C. neoformans cells in tissue is in a highly dynamic state, implying that the immune system must confront cells with varying characteristics during the course of infection.

Animals↗
PubMed2025

Dynamic changes in chromosome and nuclear architecture during maturation of normal and ALS C9orf72 motor neurons.

We have investigated changes in chromosome conformation, nuclear organization, and transcription during differentiation and maturation of control and mutant motor neurons harboring hexanucleotide expansions in the C9orf72 gene that cause amyotrophic lateral sclerosis (ALS). Using an in vitro reprogramming, differentiation and neural maturation protocol, we obtained highly purified populations of post-mitotic motor neurons for both normal and diseased cells. As expected, as fibroblasts are reprogrammed into iPSCs, and as iPSCs differentiate into motor neurons, chromatin accessibility, chromosome conformation, and nuclear organization change along with large-scale alterations in transcriptional profiles. We find that the transcriptome changes extensively during the first three weeks of post-mitotic neuronal maturation, with thousands of genes changing expression, but then is relatively stable for the next three weeks. In contrast, chromosome conformation and nuclear organization continue to change over the entire 6-week maturation period: chromosome territoriality increases, long-range interactions along chromosomes decrease, compartmentalization strength increases, and centromeres and telomeres increasingly cluster. In motor neurons derived from ALS patients such changes in chromosome conformation were much reduced. Chromatin accessibility changes also showed delayed maturation. The transcriptome in these cells matured relatively normally but with notable changes in expression of genes involved in lipid, sterol and mitochondrial function. We conclude that neural maturation is associated with large scale post-mitotic changes in gene expression, chromosome conformation and nuclear organization, and that these processes are defective in motor neurons derived from ALS patients carrying C9orf72 hexanucleotide repeat expansions.

Journal Article↗
PubMed2000

Dynamic changes of intracellular pH in individual lactic acid bacterium cells in response to a rapid drop in extracellular pH.

We describe the dynamics of changes in the intracellular pH (pH(i)) values of a number of lactic acid bacteria in response to a rapid drop in the extracellular pH (pH(ex)). Strains of Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Lactococcus lactis were investigated. Listeria innocua, a gram-positive, non-lactic acid bacterium, was included for comparison. The method which we used was based on fluorescence ratio imaging of single cells, and it was therefore possible to describe variations in pH(i) within a population. The bacteria were immobilized on a membrane filter, placed in a closed perfusion chamber, and analyzed during a rapid decrease in the pH(ex) from 7.0 to 5.0. Under these conditions, the pH(i) of L. innocua remained neutral (between 7 and 8). In contrast, the pH(i) values of all of the strains of lactic acid bacteria investigated decreased to approximately 5.5 as the pH(ex) was decreased. No pronounced differences were observed between cells of the same strain harvested from the exponential and stationary phases. Small differences between species were observed with regard to the initial pH(i) at pH(ex) 7.0, while different kinetics of pH(i) regulation were observed in different species and also in different strains of S. thermophilus.

Hydrogen-Ion Concentration↗
PubMed2002

Plastic changes in the central auditory system after hearing loss, restoration of function, and during learning.

Traditionally the auditory system was considered a hard-wired sensory system; this view has been challenged in recent years in light of the plasticity of other sensory systems, particularly the visual and somatosensory systems. Practical experience in clinical audiology together with the use of prosthetic devices, such as cochlear implants, contributed significantly to the present view on the plasticity of the central auditory system, which was originally based on data obtained in animal experiments. The loss of auditory receptors, the hair cells, results in profound changes in the structure and function of the central auditory system, typically demonstrated by a reorganization of the projection maps in the auditory cortex. These plastic changes occur not only as a consequence of mechanical lesions of the cochlea or biochemical lesions of the hair cells by ototoxic drugs, but also as a consequence of the loss of hair cells in connection with aging or noise exposure. In light of the aging world population and the increasing amount of noise in the modern world, understanding the plasticity of the central auditory system has its practical consequences and urgency. In most of these situations, a common denominator of central plastic changes is a deterioration of inhibition in the subcortical auditory nuclei and the auditory cortex. In addition to the processes that are elicited by decreased or lost receptor function, the function of nerve cells in the adult central auditory system may dynamically change in the process of learning. A better understanding of the plastic changes in the central auditory system after sensory deafferentation, sensory stimulation, and learning may contribute significantly to improvement in the rehabilitation of damaged or lost auditory function and consequently to improved speech processing and production.

Animals↗
PubMed1985

Short-term dynamic psychotherapy. V. Global assessment scale as an instrument for description and measurement of changes for 33 neurotic patients.

Global assessment scale (GAS) has not been tested out on a group of neurotic out-patients earlier. The patients in this study were selected for short-term dynamic psychotherapy by defined selection criteria and were thus a fairly homogeneous group of patients. It could be demonstrated that GAS could be used as a supplement for describing patient characteristics both at the start of treatment and at the 5-year follow-up. GAS could further be used for measuring change for this patient population after short-term dynamic psychotherapy. GAS could not be used as a predictor for dynamic change at the 5-year follow-up.

Adult↗
PubMed1999

Lack of sex difference in cerebrospinal fluid (CSF) leptin levels and contribution of CSF/plasma ratios to variations in body mass index in children.

In adults, leptin seems to cross the blood-brain barrier by a saturable transporter. This may contribute to the development of obesity. The present study in healthy children investigates leptin levels in plasma and cerebrospinal fluid (CSF) in relation to body constitution. This prospective study analyzed leptin levels in plasma and CSF samples (stored at -80 C) of patients without CNS infection or blood-brain barrier dysfunction. Inclusion criteria included temperature less than 38.5 C, C-reactive protein levels below 10 mg/L, CSF leukocyte levels less than 10(7)/L, no need for neurosurgical or oncological treatment, and no history of trauma. Four groups were designated according to body mass index. Sixty-five children (28 girls and 37 boys) entered the study. Plasma leptin (median) was 7.4 in girls and 2.6 ng/mL in boys., CSF leptin was 0.273 and 0.204 ng/mL, respectively, leading to CSF/plasma ratios of 0.045 and 0.071, respectively. Ratios were clearly dependent on body mass index percentiles (r = -0.484; P < 0.01, significant differences between groups by ANOVA). Median plasma leptin levels in the 4 groups (body mass index, <10th, 10th-50th, 50th-90th, and >90th percentile) were 2.0, 2.3, 4.1, and 8.8 ng/mL; CSF/plasma ratios were inversely related: 8.2%, 7.6%, 5.5% and 3.6%. In healthy children, CSF leptin levels account for approximately 5% of plasma levels. CSF/plasma ratios in girls are lower than those in boys, explaining why calorie intake and energy expenditure are not grossly different despite large differences in circulating plasma leptin concentrations. CSF/plasma ratios of lean children are higher than those in obese children. The dynamic changes in the CSF/plasma ratios are more pronounced in lean children, i.e. the nonlinear transport characteristics of the leptin system amplifies the information about changes in body energy stores in this population, indicating that leptin is part of a mechanism to protect the body from critical weight loss rather than to avoid obesity.

Adolescent↗
PubMed2000

Decoding temporal information: A model based on short-term synaptic plasticity.

In the current paper it is proposed that short-term plasticity and dynamic changes in the balance of excitatory-inhibitory interactions may underlie the decoding of temporal information, that is, the generation of temporally selective neurons. Our initial approach was to simulate excitatory-inhibitory disynaptic circuits. Such circuits were composed of a single excitatory and inhibitory neuron and incorporated short-term plasticity of EPSPs and IPSPs and slow IPSPs. We first showed that it is possible to tune cells to respond selectively to different intervals by changing the synaptic weights of different synapses in parallel. In other words, temporal tuning can rely on long-term changes in synaptic strength and does not require changes in the time constants of the temporal properties. When the units studied in disynaptic circuits were incorporated into a larger single-layer network, the units exhibited a broad range of temporal selectivity ranging from no interval tuning to interval-selective tuning. The variability in temporal tuning relied on the variability of synaptic strengths. The network as a whole contained a robust population code for a wide range of intervals. Importantly, the same network was able to discriminate simple temporal sequences. These results argue that neural circuits are intrinsically able to process temporal information on the time scale of tens to hundreds of milliseconds and that specialized mechanisms, such as delay lines or oscillators, may not be necessary.

Computer Simulation↗
PubMed2000

Quantitative study of dynamic behavior of cell monolayers during in vitro wound healing by optical flow analysis.

BACKGROUND: In vitro wound healing assays are experimental models commonly used to analyze cell behavior during the migration process. A new approach is proposed for the quantification of cell motility based on an optical flow method. METHODS: We assumed that cell-population dynamics can be defined by an a priori affine-motion model. Identified model parameters are used as motion descriptors quantifying both elementary and complex cell movements, either at the wound margins or within the cell monolayer. RESULTS: When compared with the estimation of cell motility calculated from wound area temporal variation, it allows a more detailed and precise characterization of cell population movements. Comparative analysis of normal and cancerous cell lines revealed that typical measured velocities were about 2 microm/h and 7 microm/h for L929 and HeLa cells, respectively, at the beginning of the wound closure. The quantification of the effect of Hoechst 33342 on cell dynamics showed a similar behavior for control and stained cells within 20 h after wound scratching, but then a decreased velocity of stained cells. CONCLUSIONS: The results demonstrate that this approach can be used to gain new insights into the dynamic changes induced by the extracellular environment and by anticancer drugs.

Animals↗
PubMed1999

Changing pattern of heart diseases in Shanghai from the 1950s to 1980s.

OBJECTIVE: To determine the pattern of dynamic change in types of heart diseases in the past 4 decades for providing a reference to treatment and prevention of heart diseases in China. METHODS: All adult cardiac patients admitted to the Zhong Shan Hospital and Hua Shan Hospital from 1948 to 1989 were analyzed. The constituent ratio of different heart diseases in the 1950s, 1960s, 1970s and 1980s was compared. RESULTS: The percentage of heart diseases among medical inpatients increased in each of the recent 4 decades, from 9.89%, 15.69%, 20.90% to 23.54% respectively. The constituent ratio of different heart diseases changed, coronary heart disease constituted the highest proportion, next came rheumatic heart disease, and congenital heart disease was in third place. Congenital heart disease, myocarditis, cardiac dysrhythmia without organic heart disease, cardiomyopathy and endocarditis increased, rheumatic heart disease, pulmonary heart disease and hypertensive heart disease apparently decreased; syphilitic heart disease could rarely be encountered. CONCLUSION: China is now facing a low overall death rate, a long life expectancy and an aging population. The incidence of heart diseases increased gradually and patterns of heart diseases kept changing. The overall trend is that heart diseases which were not related to infection are increasing while heart diseases related to bacterial infection are decreasing.

Arrhythmias, Cardiac↗
PubMed1992

Role of the health professional in ending the tobacco pandemic: clinic, classroom, and community.

Physicians and other health professionals have become complacent about the tobacco pandemic, because there is a mistaken belief that the war on smoking has been won. In reality, the survival from lung cancer is little better than it was 30 years ago, and cigarettes have become the most advertised and promoted product in society. The prevalence of overall smoking in the United States has declined by only 0.5%/y during the past decade. Among certain US minority populations, the decline has been far less or nonexistent. Traditional efforts to control the tobacco pandemic have been reactive and static, whereby government agencies, schools, and health professionals provide the public with generic information about the adverse health effects of smoking. As a result of these efforts, it is assumed that individuals will act to change their behavior. In contrast, the tobacco industry is proactive and dynamic, changing its brand-name strategies through advertising and promotion. To more effectively combat tobacco use, health officials need to move beyond patient education and adopt a more active model that includes clinic-based, school-based, and community-based tobacco-control strategies. Use of humorous, satirical images as part of paid counteradvertising campaigns and proactive health education curricula should be part of a concerted effort to end the tobacco pandemic and limit the promotional influence of tobacco companies.

Consumer Advocacy↗
PubMed1991

[Various results of the study of medico-biological aspects of alcoholism in Siberia and Far East].

To study the dynamic changes in alcohol abuse, a new methodological approach has been developed which implies staged realization. Stage one was aimed at the search for integral clinical-dynamic characteristics as well as social and psychological properties to make identification of the clinical phenotype reliable. Stage II--at introduction of integral constitution-morphology indicators representative of the disease predisposition-stability. The analysis of medicosocial characteristics for the last 8 years has been performed at Stage III. Calcium homeostasis and related hormones and enzymes were evaluated at Stage IV. The data obtained permitted identification of a complex of structural manifestations underlying alcohol embryopathy of the brain.

Alcoholism↗
PubMed1990

[Myosin ATPase activity in somatic muscle fibers in different degree of pH of the pre-incubation medium].

The problem on presence of muscle fibers (MF) types is an actual one, since it is a prerequisite to forecasting certain changes in MF under different conditions. The aim of the investigation has been to find out whether independent groups of MF exist or whether they react as a whole population to gradual changes in pH of the preincubational medium, when dynamic changes in m-ATPhase activity are studied. In serial transversal cryostate slices 10 mcm thick m-ATPhase activity has been defined in MF at preincubation of the slices in media having various pH. The experiment has had three series. In the I--the ventral denticulate muscle with universal biomechanical properties has been investigated; preincubation has been carried out in media having pH from 3.0 up to 11.0 with the intervals 0.5 pH. In the II--besides the muscle mentioned the fast brachial muscle and the force triceps muscle have been studied; preincubation has been performed only at pH 9.5, since in the I series two dissociated groups of MF have been distinguished. In the III series, at studying the same three muscles m-ATPhase activity has been detailed with their preincubation at pH from 3.8 up to 4.5 with the interval 0.1. The m-ATPase activity begins to manifest in various MF at pH of the preincubational medium within the limits of 3.8-4.2. A gradual increase in amount of MF that are revealing, as pH is gradually increasing, evidences most likely against independence of separate groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Immune response against P815X2 mastocytoma growing in syngeneic DBA/2 mice. III. Morphometric assessment of the dynamic changes in post-capillary venules as regulatory elements of lymphocyte recirculation in tumor-draining lymph nodes.

To evaluate the dynamics of lymphocyte recirculation in tumor-bearing mice, the post-capillary venules (PCV) were subjected to quantitative measurements in the regional (RLN) and nonregional (NRLN) lymph nodes during the progression of P815X2 mastocytoma in syngeneic DBA/2 mice. Mice were sacrificed at two-day intervals, and RLNs and NRLNs were analysed for their content of B- and T-lymphocytes and their subsets, demonstrated by immunoperoxidase technique using monoclonal antibodies; Anti-Thy 1.2 (T cells), Anti-Lyt 1 (T-helper cells), Anti-Lyt 2 (T-suppressor cells), and Anti-I-Ad (B cell) antigens, separately in the B- and T-cell compartments. In the PCVs, migration index (MI) and endothelial height (Hend) were measured. There was a biphasic elevation of MI in the RLNs, as compared with only a late rise in the NRLNs, reaching the peak (1.54) on day 14. In RLNs, there was a sharp reduction in Hend starting from the values (6.37 microns) on day 2, down to 4.79 microns on day 8. This is followed by rapid elevation close to the second-day values, e.g. 6.07 on day 10. The changes in MI paralleled the early influx of B cells, as evidenced by the decrease of Thy 1.2+/I-Ad+ cell ratio and a late recruitment of T cells as indicated by the elevation of that ratio as well as the Hend values in both the RLNs and NRLNs. The present experiment shows that morphology of PCVs in the RLNs and in NRLNs of P815X2-bearing mice is subjected to alterations reflecting the dynamics of lymphocyte recruitment into these organs. When combined with lymphocyte subset enumeration using monoclonal antibodies, the quantitative analysis of the PCVs permits predictions to be made on the recirculatory activity of these cell populations during the tumor progression.

Animals↗
PubMed1996

Persistence of dominant T cell clones in synovial tissues during rheumatoid arthritis.

In a previous study, we showed that the T cell repertoire is biased in the synovial membrane (SM) compared with peripheral blood during rheumatoid arthritis (RA). The same bias was observed in different joints from the same patient and seems to be the same over time. To discover whether this bias was due to expansion of a clonal subset resulting from activation by conventional Ag(s) or to polygonal stimulation by superantigen(s), we sequenced more than 650 TCRBV-D-J junctional regions from freshly isolated SM and peripheral blood of two DR4-RA patients. From each patient, two SM were obtained on the same day, and a third was obtained later. Several dominant clones were found in SM but not in peripheral blood. Some of them were found only at the first time point in anatomically different SM, the majority persisted over time, and others were detected only at the second time point. Analysis of the complementarity-determining region 3 (CDR3) showed a bias in TCRBD and amino acid usage. Valine, encoded by randomly inserted N nucleotides, was used by 45% of dominant clones compared with 18% in the control population (p less than 0.001). In addition, GXXG and TSG motifs were frequently observed in the CDR3 of these dominant clones. These data indicate a dynamic TCR selection process during the perpetuation phase of RA. The dynamic changes of dominant clones also suggest a determinant spreading mechanism during RA.

Amino Acid Sequence↗
PubMed1996

Seasonal population dynamics of Halipegus occidualis and Halipegus eccentricus (Digenea:Hemiuridae) in their amphibian host, Rana clamitans.

The seasonal population dynamics of Halipegus occidualis and Halipegus eccentricus (Hemiuridae) in their amphibian host, the green frog (Rana clamitans), were examined for 3 yr (weekly, April through October). Frogs were caught, marked, and examined for H. occidualis and H. eccentricus, both of which occur as immatures and adults in the buccal cavity. Frogs were then released and allowed to continue natural recruitment and loss of the parasites. It was thus possible to monitor individual infrapopulations over successive time periods. One-hundred and forty-nine frogs were caught and released, with a total of 328 observations. Overall, the levels of both parasites among male and female frogs were similar, as were levels of infection among adult and juvenile hosts. There was, however, no correlation between the total number of H. occidualis and the body size (snout-vent length) of R. clamitans. In contrast, there was a significant correlation between the total number of H. eccentricus and frog size. Recruitment of both species began in May, peaked in June/July, and ended in July (H. eccentricus) or August (H. occidualis). In general, both the prevalence and relative density of H. occidualis was greater than that of H. eccentricus and may be related to space constraints in the buccal cavity of R. clamitans. Adults of both species were observed from April through October. Following increases in parasite recruitment, infrapopulation sizes declined in September 1992 and in August of 1993 and 1994. Examination of variance to mean ratios indicated that both species were overdispersed in the frogs. Large declines in the variance to mean ratios for H. occidualis after periods of greatest recruitment are most likely associated with the loss of larger infrapopulations, suggesting that there may be density-dependent regulation of infrapopulation size. By monitoring individual hosts using the mark-release-recapture protocol, dynamic changes in parasite infrapopulations were observed, e.g., there were losses of immature worms and rapid changes in infrapopulation sizes, observations that would not be made with typical host-parasite systems.

Animals↗