Acta biochimica et biophysica Hungarica最新文献

A mathematical model of the olfactory bulb is presented to study the dynamics of the bulbar information processing. A two level model is adopted to describe both neural activity and synaptic modifiability. The model takes explicitly into account the existence of lateral interactions in the mitral layer, and the synaptic modifiability of these connections. A series of bifurcation phenomena among fix points, limit cycle and strange attractors have been demonstrated. Chaos occurred only in the case of excitatory lateral connections. Coexistence between oscillation and chaos, and synaptic modification induced transition have also been found. The model attempts to demonstrate the associative memory character of the olfactory bulb. Odour qualities are coded in distributed spatial amplitude patterns. Differential equations for the mitral and granule cell activities have been supplemented by a continuous-time local learning rule. A nonlinear forgetting term and a selective decreasing term is added to the Hebbian learning rule. A learned odour can be recalled by a subset of the pattern. There is a strict restriction on the parameters: only those values can be admitted which generate physiologically justified activity signals.

The criteria of Msc-positivity were: typical accumulation of hot spots in 2 directions of planar scan in the 24-48-hr measurements, while in atypical cases the hot spots were present only in the 48 hr picture. Twenty-one male volunteers were assessed. 18 of them had ACM (2 patients were studied repeatedly). The negative and positive control cases exhibited the expected Msc pattern. Seven ACM patients were regarded typically positive, in 5 cases atypical positivity was stated, and 6 patients were classified as Msc negatives. The heart lung activity ratio was 1.75 +/- 0.45 and 1.68 +/- 0.44 for typical and atypical positive cases, respectively. The control and DCM H/L ratios were 1.15 and 1.3 +/- 0.2, respectively, in AMI the H/L was 1.91, in DCM of dilatative phase it was 1.55 +/- 0.06 with serum myosin in the normal range. Heart dilation in the DCM groups: 5 dilated out of 7 typically positive cases while in atypically positive, and negative cases the dilation occurred in 2 out of 5 and 1 out of 6 cases, respectively. Low LV-EF (less than 45%) were found in ratios of 4/7, 2/5, and 1/6 in typically positive, atypically positive and negative cases, respectively. Elevated PCP similar ratios. In the same groups pathological ECG was seen in ratios of 5/7, 1/5, and 1/6, respectively. The g-GT activity was enhanced in all cases, there was, however, no evident correlation between the actual enzyme activity and intensity of hot accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective extraction procedure was applied for obtaining different proteins from sarcoplasmic reticulum vesicles following the main steps of previous observations. High concentration of a nonionic detergent, such as polyoxyethylene-10-lauryl ether (C12E10) prevented the formation of Ca(2+)-ATPase crystals. It has been observed that only the 300 kDa protein could induce crystallization from among proteins being undissolved from of membrane. A modification of MacLennan's procedure--applied for ATPase precipitation from deoxycholate solubilized sarcoplasmic reticulum--has been described and an ammonium acetate precipitated Ca(2+)-ATPase was used in the experiments for increase of Ca(2+)-ATPase concentration in the crystallization process. The repeated supplementation of purified and C12E10 solubilized Ca(2+)-ATPase with ammonium acetate precipitated Ca(2+)-ATPase made possible a formation of larger and larger crystals with different periodicity.

Factors influencing the operation of a vertical bioreactor segmented with perforated plates supporting immobilized yeast cells were studied. It was found that the most important factors are the length-diameter (L/D) ratio of the reactor and the dilution rate. It was supposed that the optimal L/D ratio is about 1. The operation of the reactor was more favourable at a low liquid phase-solid phase ratio. The spatial distribution of the biocatalyst had only a slight, if any effect. The periodically changed direction of feed flow has no improving effect on the fermentation process.

Several reactions of the Ist and IInd phase of biotransformation have been reported to be under a negative cyclic-AMP dependent control. Conjugation of bilirubin and glucuronidation of morphine were investigated in isolated mouse hepatocytes and in mouse hepatocyte microsomes, respectively. N6,O2-dibutyryl cyclic-AMP did not inhibit conjugation of bilirubin in isolated hepatocytes. ATP and the dissociated catalytic subunit of the cyclic-AMP dependent protein kinase did not influence the glucuronidation of morphine, while inhibited the formation of p-nitrophenol glucuronide in microsomes prepared from isolated mouse hepatocytes.

An approach to ribosomal RNA turnover studies in which cytoplasmic RNA was extracted and subsequently fractionated to isolate ribosomal RNA is reported. The presumption that the pool of 28S and 18S RNAs represented ribosomal RNA, exclusively, proved false and led to erroneous results of ribosomal RNA turnover. Polyadenylated RNAs exhibited a heterogeneous size distribution and, although constituting only 3% (w/w) of the cytoplasmic RNA extract, accounted for fully 10% of radioactivity of the presumptive ribosomal RNA pool. Profiles from the radioactivity data suggested that the discrepant results were due to these polyadenylated RNAs. An additional analytical procedure, an oligo (dT) cellulose column chromatography of the RNA extract prior to the sucrose density gradient fractionation step, performed as described in this paper, proved an effective remedy for this error.