Study of some enzyme systems by means of the differential microrespirometer

Three enzymic phenomena, inactivation by oxygen, Q_OO2 measurements of a dehydrogenase system, and hydrolysis of acetyl phosphate by a phosphatase of Clostridium kluyveri, were studied by means of the differential microrespirometer. Respiration of yeast cells was also measured with the same instrument. All results obtained in the four types of study agreed closely with earlier results obtained with the Warburg apparatus. The amount of sample needed was of the order of 1/100 to 1/200 of that necessary for comparable study with the Warburg apparatus. The advantages of the instrument in enzyme isolation and purification studies are discussed.     

Study of cutaneous nociception by means of chemical agents

The response was investigated of cutaneous C-fiber polymodal mechano-thermo-sensitive sensory units (SMT units) to injecting potassium, acetylcholine, and methacholine ions at noxious and subnoxious concentrations into the arteries of anesthetized cats. Subnoxious chemical stimulation induced low-frequency excitation in SMT units. The parameters of firing in these units, when subjected to excitation during noxious or subnoxious chemical stimulation, may be used to estimate the analgesic action of local anesthetics. Local anesthesia may be achieved by inhibiting exclusively high-frequency discharge in SMT units, without complete blockade of these sensors. We propose use-dependent neural excitation blockers for this purpose. SMT units were found to be inhibited in this way by mechanical stimulation under the action of lidocaine or n-propylaj-maline. Mathematical modeling of C-fibers showed that slow alterations in ionic permeability play a major part in determining firing rate produced by chemical stimulation.Experimental Cardiological Research Institute, All-Union Cardiological Research Center, Russian Academy of Medical Sciences, Moscow. Translated from Neirofiziologiya, Vol. 24, No. 5, pp. 517–529, September–October, 1992.     

Study of eye proteoglycans by means of infrared spectroscopy

The infrared spectra of standard hyaluronic acid, proteochondroitin sulfate, aggregates of proteoglycans and spectra of the vitreous body, cornea and sclera were obtained in the region of 4000-400 cm-1. The comparative analysis of the spectra of these tissues and spectra made it possible to identify greater absorption bands of these biopolymers.     

Study of the pathogenesis of toxoplasmosis by means of tagged atoms]

The authors' investigations showed a principal possibility of labeling toxoplasma with radioactive isotopes on condition of the administration of the latter in vivo into the donor animals infected with toxoplasmosis. The labeled atom method could be used for studying the pathogenesis of toxoplasmosis in the experimental animals, particularly at the early periods of the infectious process. The use of the labeled atom method permitted not only to confirm the results obtained by parasitological and pathomorphological studies, but also to reveal the fact of a primary parasitemia, later confirmed by biopsy. In combination with other methods of study the labeled atom method can be used for studying various aspects of the problem of toxoplasmosis, particularly of the mechanisms of transmission of the infection.     

Study of the antigenic structure of Salmonella by means of immunoelectrophoresis]

The method of immunoelectrophoretic analysis was applied to the study of the antigenic structure of 180 freshly-isolated and laboratory cultures of salmonellae belonging to 29 serological types. A complicated set of specific and common antigens of bacteria was revealed in direct and cross experiments with the use of homologous and heterogenous antisera; immunophoregrams were drawn for each of the serological type under study. General regularities in immunophoretic, diffuse and serological characteristics of the individual antigens of salmonellae were established. It was shown that different serological types of salmonellae possessed surface K antigens along with the O and H antigens. On immunophoregrams K-antigens of salmonellae were revealed in the form of a bright precipitation arch in the central or the anode zone; O antigens gave a characteristic two-component precipitation line in the cathode zone of the phoregram.     

Study of the heat treatment of hemoglobin by means of spin labels

Electron spin resonance measurements on oxyhemoglobin labelled with nitroxide spin labels indicate that conformational changes occuring in this protein during heat treatment manifest themselves in changes: 1) of the rotational correlation time; 2) of the equilibrium between two isomers of the labels. The results indicate that the denaturation process in oxyhemoglobin corresponds to at least a two step transition, with and indication that the changes at the tyrosine pocket of the α₁β₂ (Tyr 145β) contact may be continuous with temperature.     

Study of the genetic code adaptability by means of a genetic algorithm

We used simulated evolution to study the adaptability level of the canonical genetic code. An adapted genetic algorithm (GA) searches for optimal hypothetical codes. Adaptability is measured as the average variation of the hydrophobicity that the encoded amino acids undergo when errors or mutations are present in the codons of the hypothetical codes. Different types of mutations and point mutation rates that depend on codon base number are considered in this study. Previous works have used statistical approaches based on randomly generated alternative codes or have used local search techniques to determine an optimum value. In this work, we emphasize what can be concluded from the use of simulated evolution considering the results of previous works. The GA provides more information about the difficulty of the evolution of codes, without contradicting previous studies using statistical or engineering approaches. The GA also shows that, within the coevolution theory, the third base clearly improves the adaptability of the current genetic code.     

An Observational Study on the Perceptive and Physiological Variables During a 10,000-m Race Walking Competition

ABSTRACT: Vernillo, G, Agnello, L, Drake, A, Padulo, J, Piacentini, MF, and Torre, AL. An observational study on the perceptive and physiological variables during a 10,000-m race walking competition. J Strength Cond Res 26(10): 2741-2747, 2012-In this study, we observed the variations on physiological and perceptual variables during a self-paced 10,000-m race walking (RW) event with the aim to trace a preliminary performance profile of the distance. In 14 male athletes, the heart rate (HR) was monitored continuously throughout the event. The rating of perceived exertion (RPE) was collected using the Borg's 6-20 RPE scale placed at each 1,000 m of an outdoor tartan track. Pacing data were retrieved from the official race results and presented as percent change compared with the first split time. The athletes spent 95.4% at 90-100% of the HRpeak, whereas the other work (4.6%) was negligible. During the race, a shift toward higher HR values was observed because % HRpeak increased by 3.6% in the last vs. the first 1,000-m sector (p = 0.002, effect size [ES] = 1.55 ± 0.68, large). The mean RPE reported by the athletes in the last 1,000 m was significantly higher than in the first 5 sectors (p < 0.02, ES = 1.93-2.96, large to very large). The mean percent change increased between the first 6 sectors and the last 1,000-m sector (p < 0.01, ES = 1.02-2.1, moderate to very large). The analysis of walking velocity at each 1,000-m sector suggested the adoption of a negative pacing. In conclusion, the RPE may be a valid marker of exercise intensity even in real settings. Match physiological and perceptual data with work rate are required to understand race-related regulatory processes. Pacing should be considered as a conscious behavior decided by the athletes based on the internal feedback during the race.     

Study of tissue proteoglycans by means of infrared spectroscopy]

The infrared spectra of the hyalin cartilage vitreous body, cornea, sclera and spectra of standard normal Na(+)-salts of hyaluronic acid, chondroitin-4-sulfate, chondroitin-6-sulfate, protein-chondroitin-keratan-sulfate, aggregates of proteoglycans of the hyalin cartilage, heparin fractions containing 3 and 4 residues of sulfuric acid per dimer of polymer were obtained. The comparative analysis of the spectra for tissues and of the spectra for proteoglycans made it possible to identify different proteoglycans in the same tissues.     

Congenital Perceptive Deafness: Role of Intrauterine Rubella

Rubella antibody was detected in 85 (61%) of 139 children aged from 6 months to 7 years with congenital perceptive deafness. Of the 112 children who were aged under 4 years 61 (54%) had rubella antibody (seropositive) compared with 7·1% in randomly selected children of the same age. A close correlation was found between the presence of antibody in children with perceptive deafness and (1) a maternal history of rash or contact in early pregnancy, and (2) with the presence of other rubella-type defects. Intrauterine rubella was thought to be the cause of the deafness in 82 (59%) of the 139 children, in 60 of whom deafness was the only rubella defect detected. Thus intrauterine rubella should be considered a likely cause of congenital perceptive deafness in a child under 4 years in whom rubella antibody is present.     

Perceptive performance and feeding behavior of calanoid copepods

The goal of this study was to determine variables associatedwith calanoid feeding behavior, and thus, to improve our understandingof the basics of calanoid feeding rates. These variables includedperiods and frequency of appendage motion, rates of cell clearance,distance at which a copepod first reacts to a cell which iseventually captured, and rate of water flow through the areacovered by the motions of a copepod's feeding appendages. Theeffects of these variables on feeding rates were determinedfor copepodids and adult females of the calanoid copepod Eucalanuspileatus at phytoplankton concentrations covering the rangeencountered by this species on the south-eastern shelf of theUSA. Our results indicate that the distance at which E.pileatusperceives phytoplankton cells increases {small tilde}2-foldas food concentrations decrease from 1.0 to 0.1 mm³ l^–1.These results lead us to hypothesize that this is due to increasedsensitivity of chemosensors on the copepods' feeding appendages.This 2-fold increase in perceptive distance amounts to a near4-fold increase in perceived volume which is close to the 6-foldincrease in volume swept clear (VSC) from 1.0 to 0.1 mm³ l^–1of Thalassiosira weissflogii. We assume that the increases inVSC by planktonic copepods, when food levels are below satiation,are largely a function of the sensory performance of the individualcopepod.     

荧光标记法检测不同毒物对细胞骨架的影响

细胞骨架(Cytoskeleton)主要由微管(Microtubule,MT)、微丝(Microfilament,MF)以及中间丝(Intermediate filament,IF)这三种类型组成。它们在细胞的形态维持、物质运输、信号转导、能量转换及细胞的运动和分裂等多个过程中发挥着重要的作用。其中,由肌动蛋白组成的微丝是真核细胞中含量最丰富的一种蛋白复合体,以解聚时的球状肌动蛋白G-actin(Globular actin)或聚合时的纤丝状肌动蛋白F-actin(Filamen-tous actin)形式存在。正常细胞中肌动蛋白两种形态的转换处于动态平衡,共同行使细胞的变形运动、胞质分裂、基质附着和胞间连接等多…