Markov process of maintained impulse activity in central single neurons

To clarify the stochast properties of the maintained impulse activity of the central nervous system, we proposed a measure of statistical dependency on the basis of Shannon's entropy. This measure could provide the Markov properties of the neural impulse sequences, representing the necessary and sufficient condition for the statistical dependence. The order of Markov process of the sequence is determined by the conditional entropy which is derived from the joint entropy. Here the joint entropy in the case of Gaussian process is directly related with the covariance matrix which is substituted for the matrix of the serial correlation coefficients. Therefore the condition to determine the order of Markov process is obtained by the equation of the matrices of the serial correlation coefficients. The order of Markov process of the neural impulse sequences recorded from the mesencephalic reticular formation (MRF), red nucleus (RN), and lateral geniculate nucleus (LGN) neurons has been estimated. The maintained impulse activity of the MRF and RN neurons had from the 2-nd to 4-th order Markov property, while that of the LGN had no Markov property, in the consecutive impulse sequences.     

Novel chondrogenic and chondroprotective effects of the natural compound harmine

A significant number of natural compounds have been shown to regulate the behavior of the cells, in collaboration with cellular proteins. CCN2/connective tissue growth factor (CTGF) has been reported to have essential roles in cartilage development, chondrocyte proliferation and differentiation as well as regulation of the extracellular matrix metabolism. Previous studies demonstrated the capability of CCN2 to regenerate surgical defects in articular cartilage of rat knee. Also, transgenic mice over-expressing cartilage-specific CCN2 were shown to be more resistant to aging-related cartilage degradation. We hypothesized that small molecules that induce CCN2 in chondrocytes could be novel candidates to increase the resistance to aging-related cartilage degradation, or even to correct cartilage degenerative changes incurred in OA. Therefore, this study screened a compound library and identified the β-carboline alkaloid harmine as a novel inducer of CCN2 in human chondrocytic HCS-2/8 cells and osteoarthritic articular chondrocytes. Harmine increased the expression of the cartilage markers aggrecan and COL2α1, as well as that of the master regulator of chondrogenesis, SOX-9. Moreover, harmine notably induced chondrogenesis of prechondrocytic ATDC5 cells in micromass cultures. The chondroprotective effect of harmine was investigated under inflammatory condition by stimulation with TNFα, and harmine was shown to ameliorate TNFα-induced decrease in expression of CCN2 and cartilage markers. These findings uncover novel chondrogenic effects of harmine and indicate harmine as a potential drug for prevention and/or repair of cartilage degradation.     

Concanavalin A Modifies Allo-specific Sperm-Egg Interactions in the Ascidian, Ciona intestinalis

In the self sterile ascidian, Ciona intestinalis , the spermatozoa rarely bind to the vitelline coat of autologous eggs and never penetrate it. We report here that concanavalin A (ConA), a lectin recognizing mannose or glucose residues of carbohydrates, can modify these self- and nonself-specific sperm-egg interactions. When eggs were pretreated with 0.1–0.5 mg/ml of ConA, about two thousand spermatozoa became attached to the autologous vitelline coat within five minutes of insemination. The effect of ConA was not modified by the addition of D-mannose or pretreatment of spermatozoa with ConA, showing that ConA does not function merely as a ligand bridging the sperm and vitelline coat. In contrast to the marked enhancement of sperm-egg binding, ConA did not facilitate the penetration of spermatozoa through the autologous vitelline coat. Even in non-autologous insemination, it blocked the sperm penetration and, consequently, fertilization did not occur, as shown by Rosati et al. (1978). D-Mannose, when mixed with ConA in advance, completely abolished this inhibitory effect of ConA. Lotus agglutinin, a fucose-binding lectin, was less effective and wheat germ agglutinin and soy bean agglutinin had no effect on sperm entry in the perivitelline space. The results of this study are discussed in relation to the possible involvement of mannosyl and/or glucosyl glycoconjugates in allo-specific sperm-egg interactions.     

Polyploid progeny from triploid hybrids of Phegopteris decursivepinnata (Thelypteridaceae)

Journal of Plant Research - Phegopteris decursivepinnata includes diploids, tetraploids, and triploid hybrids based on x = 30. We obtained polyploid progeny from triploid hybrids...     

Angiotensin II mediates hyperadrenergic activity evoked by sodium restriction in essential hypertension

We examined the possible involvement of angiotensin II in the modulation of circulating norepinephrine produced by acute sodium restriction in essential hypertensive patients (n = 18). Sodium restriction potentiated plasma level of norepinephrine in parallel with an increased plasma renin activity (r = 0.81, F = 31.2, p less than 0.05 given by the percent changes). An intravenous infusion of sarcosine-1, isoleucine-8 angiotensin II produced a significant fall in mean arterial pressure (-6 +/- 2 mmHg, p less than 0.05) in patients on sodium restriction but not before sodium restriction, while the infusion of the antagonist produced a greater decrease (p less than 0.05) in plasma norepinephrine with sodium restriction (-158 +/- 23 pg/ml, p less than 0.05) when compared to that obtained before sodium restriction (-91 +/- 11 pg/ml, p less than 0.05). A single oral administration of an angiotensin I converting enzyme inhibitor, captopril caused a greater fall (p less than 0.01) in mean arterial pressure after sodium restriction (-32 +/- 3 mmHg, p less than 0.05) compared to that given before (-21 +/- 3 mmHg, p less than 0.05). However, sodium restriction did not affect the magnitude of reflex increase in plasma norepinephrine to hypotension evoked by captopril (from +88 +/- 16 pg/ml to +87 +/- 17 pg/ml; p greater than 0.05). It can be interpreted that acute sodium depletion results in a substantial contribution of angiotensin II to the expression of hyperadrenergic activity.     

The Almost-one Parameter Hypothesis Applied to Pharmacokinetics of Ethanol Infusion

They say that the pharmacokinetics of constant-rate intravenous infusion of ethanol obeys the Henri-Michaelis-Menten (H-M-M) model. In analysing the original data from the viewpoint of the almost-one parameter hypothesis (see box 1), we found that the whole process should be divided into four phases and the H-M-M model was valid only in the last phase.     

A novel model of obesity-related diabetes: introgression of the Lepr(fa) allele of the Zucker fatty rat into nonobese Spontaneously Diabetic Torii (SDT) rats.

An fa allele of the leptin receptor gene (Lepr(fa)) of the Zucker fatty rat was introduced into the genome of the Spontaneously Diabetic Torii (SDT) rat, an inbred model of nonobese type 2 diabetes mellitus, through the 'Speed congenic method'. The newly established congenic strain of a SDT rat for Lepr(fa) was maintained by intercrossing between fa-heterozygous littermates, and the phenotypes related to obesity and diabetes were investigated till 32 wks of age. SDT fa/fa rats of both sexes exhibited obesity, adiposity and insulin resistance associated with hyperphagia from the loss of leptin action. Interestingly, they developed diabetes from 5 wks of age in males and 8 wks in females with the incidences reaching 100% at 16 wks in males and 73% at 32 wks in females. In contrast, heterozygous (+/fa) and wild-type (+/+) rats developed spontaneous nonobese diabetes in males from approximately 20 wks, but not in females, as with the original SDT rats. These results indicate that the fa gene accelerates the onset of diabetes in SDT rats by making adiposity and/or insulin resistance as potent risk factors for development of their diabetes. The SDT.Lepr(fa) congenic rat strain is expected to be a novel model of obesity-related diabetes and could be a useful tool for studies of the genetic backgrounds of diabetes in response to fa-induced obesity.