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Biophysical approaches for studying the integrity and function of tight junctions.

Cell-cell adhesion is an extremely important phenomenon as it influences several biologically important processes such as inflammation, cell migration, proliferation, differentiation and even cancer metastasis. Furthermore, proteins involved in cell-cell adhesion are also important from the perspective of facilitating better drug delivery across epithelia. The adhesion forces imparted by proteins involved in cell-cell adhesion have been the focus of research for sometime. However, with the advent of nanotechnological techniques such as the atomic force microscopy (AFM), we can now quantitatively probe these adhesion forces not only at the cellular but also molecular level. Here, we review the structure and function of tight junction proteins, highlighting some mechanistic studies performed to quantify the adhesion occurring between these proteins and where possible their association with human diseases. In particular, we will highlight two important experimental techniques, namely the micropipette step pressure technique and the AFM that allow us to quantify these adhesion forces at both the cellular and molecular levels, respectively.

Biophysics↗

[The significance of multiple neuromediator activity in supporting integrative brain functions].

Properties were studied of reactions of neural cells of the sensorimotor cortical area to locally microionophoretically administered l-glutamate, acetylcholine, norepinephrine and gamma-aminobutyric acid. It is shown that neuronal reactions to the action of the above-mentioned transmitters differ both in direction of change in the impulse activity frequency and in temporal offracteristics (latency and duration of after-effect). It is substantiated that due to the specificity of temporal ranges of action of the transmitter on neural cells, the possibility of effective interaction and temporal coding of heterofunctional information is provided.

Acetylcholine↗

Power spectrum of heart rate variability: a non-invasive test of integrated neurocardiac function.

Under steady state conditions, frequency specific oscillations in the heart rate record reflect beat-to-beat autonomic control of sinus node activity. Using an autoregressive model, samples (2.5 min) of continuous ECG records were analyzed in 36 healthy young adults during supine rest (45 min), orthostatic stress and controlled respiration. In the supine state, constancy of heart rate was achieved (mean HR 62.8 bt/min +/- 4.88 SD). However, the 0.1 Hz peak spectral power varied considerably: average coefficient of variation was 34% compared to only 8% for heart rate. When breathing rates were synchronized to a metronome there was a small insignificant decrease in the peak power at 0.1 Hz compared to spontaneous respiration. Standing produced a significant increase in the peak power at 0.1 Hz especially during synchronized breathing. There was a maximum increase in the low frequency (0.1 Hz) peak power of 40 (bt/min)2. Hz-1 at a controlled breathing frequency of 0.25 Hz in the standing compared to supine position. The data show that reproducibility of the power spectrum heart rate variability is best achieved at controlled but physiologic respiratory rates and, preferably, in the upright position.

Adult↗

Metaiodobenzylguanidine as an index of the adrenergic nervous system integrity and function.

The radiopharmaceutical, metaiodobenzylguanidine (MIBG) acts as an analog of norepinephrine (NE). Experiments in rats were carried out to determine how closely the movements of [125I]MIBG in the heart mimicked those of [3H]NE, and if the changes [125I] MIBG concentrations would reflect injury to, and function of, adrenergic neurons in the heart. Injury to adrenergic neurons by 6-hydroxydopamine substantially reduced the uptake of [125I] MIBG into the left ventricle, but the effect was less than that on uptake of [3H]NE uptake and concentration of endogenous NE. Similarly, when desmethylimipramine was given to inhibit the uptake-1 pathway of neurons, the reduction in uptake of [125I]MIBG was statistically significant but less than that of [3H]NE; part of this difference may be attributable to partial uptake of [125I]MIBG into neurons by a diffusion pathway. Substantial fractions of [125I]MIBG and [3H]NE were displaced from the heart by the sympathomimetic drug, phenylpropanolamine. When adrenergic neurons of the heart were stimulated by feeding of rats, the disappearance rates of [3H]NE and [125I]MIBG from the heart were significantly increased. Although not a perfect analog of [3H]NE, [125I]MIBG appears to enter and leave the heart in patterns similar to those of [3H]NE. Thus, movements of [125I]MIBG give indices of adrenergic neuron injury and function in the heart.

3-Iodobenzylguanidine↗

[Contributions to the psychodynamic approach to understanding the phenomenon of music].

Based on different writings from different periods, this article gives us some of the psychodinamic view of musical phenomenon. It is divided in three parts. 1. The initial one is about general aspects of musical phenomenon. Music has a hihg power of symbolization, due to its ambiguity and simultaneity of elements. It can make a change on the common state of consciousness. Music also can influence on the Ego's cognitive style. Music has relationship with both the Ego's dissociative function and Ego's integrative function. 2. The secon part refers to the affective nature of music. Music release libidinal energy mainly through rhythm; for exemple we see the link between and dance in primitive societies. It also gives expression for emotional life, and arouses emotions too. 3. The third part refers to structural and functional aspects of music. This last part talks about the role of music to the listener and to the creative musician; it presents an analogy between the structure of the music and structure of the dreams. The joy of music involves the whole personality and music may be used to expand the Self.

Affect↗

Post-noise-exposure auditory sensitivity and temporal integration recovery functions.

Normal-hearing young adults (N:12) were exposed to a band-limited noise (1.4-2 kc/s) at 100 db SPL for 15 min. Pre- and post-exposure threshold measurements were made at 2 and 4 kc/s at durations of 500 and of 20 msec, at time intervals of TTS2, TTS15 and every 30-min interval thereafter for 4 hrs. Greater TTS occurred at both frequencies with the 500-msec than with the 20-msec duration. Threshold recovery patterns over time were similar for both durations but thresholds for the 20-msec duration recovered sooner. There was a delayed recovery function at 4 kc/s for the relative differences (20 vs 500 msec). Implications of the findings were discussed.

Acoustic Stimulation↗

Effect of carprofen and indomethacin on gastric function, mucosal integrity and generation of prostaglandins in men.

The effects of indomethacin and carprofen on gastric secretion, serum gastrin level, electropotential difference, gastric microbleeding, DNA loss, mucosal blood flow and the production of mucosal prostaglandins (PGs) were investigated in a double-blind cross-over study in 18 healthy volunteers after one week of treatment. We did not observe any significant changes in basal and pentagastrin-stimulated gastric secretory parameters, serum gastrin level and electro-potential difference before and after treatment with these drugs. Mucosal blood flow was significantly reduced following indomethacin treatment. The most pronounced differences were found in endoscopic score studies of gastric mucosa. After indomethacin all subjects developed multiple erosions, submucosal haemorrhages, and half of them showed diffuse antral erythema. These effects were accompanied by a significant increase in both gastric microbleeding and DNA loss, and significant decrease in the production of PGE2. We concluded that carprofen, in contrast to indomethacin, did not alter gastric mucosal integrity and production of PGE2. This study indicates that the gastric mucosal damage by non-steroid anti-inflammatory compounds (NOSAC) depends upon the suppression of PGE2 biosynthesis, and that endogenous PGE2 is involved in the control of mucosal blood flow and mucosal integrity.

Adult↗