The relationship between muscle kinetic parameters and kinematic variables in a complex movement.

Kinematic variables of the vertical jump (jumping height, jump phase durations and joint angles) were measured on 39 male physical education students. In addition, kinetic parameters of the hip and knee extensors, and of the plantar flexors (maxima voluntary force and its rate of development) were recorded on the same subjects, in isometric conditions. The results demonstrated significant positive correlations between kinetic parameters of the active muscle groups and jumping height (r = 0.

Accuracy constraints upon rapid elbow movements.

Kinematic and myoelectric variables associated with rapid elbow-flexion movements of various distances to targets of various widths were studied. The movement time in these experiments conformed to Fitts' law: movement time increased with target distance and decreased with target width. Peak movement velocity, electromyograph (EMG) duration, and EMG quantity were poorly described by Fitts' law, for increases in target width were accompanied by increases in these variables.

Increased expression of the N-myc gene during normal and neoplastic rat liver growth.

The activation of N-myc and c-myc genes has been implicated in the genesis of a variety of cancers. In order to determine whether this activation is related to the process of cell growth, we examined N-myc and c-myc expression in rat hepatocytes when growth was stimulated by partial hepatectomy and in rat liver during neoplastic growth induced by diethylnitrosamine. The levels of N-myc and c-myc mRNAs, which are very low in hepatocytes from normal rats, were increased at least 20-fold within 3 h after partial hepatectomy and decreased rapidly by 6 h.

Practice improves even the simplest movements.

Three subjects practiced accurate, fast elbow flexions of 54 degrees to a 3 degrees wide target. Movements of 36 degrees, 54 degrees and 72 degrees were then tested. Comparison over the three distances showed that the normally monotonic relationship between movement distance and movement time is alterable by specific training.

Expression of c-myc is under dietary control in rat liver.

Expression of c-myc has often been related to the control of growth and differentiation of a variety of cell types. However, in some cases, such a relation has not been found. The rate of cell division is very low in liver, but c-myc expression is yet easily detected.

Movement deficits caused by hyperexcitable stretch reflexes in spastic humans.

Spastic patients were instructed to make accurate, rapid ankle dorsiflexion and plantarflexion movements over different distances to a target. Ankle position and surface electromyograms (EMGs) from tibialis anterior (TA) and soleus (SOL) muscles were recorded. In 3 of 8 spastic patients tested, dorsiflexion evoked velocity-dependent activation of the antagonist (SOL) muscle which impeded the movement to the extent that the limb unintentionally reversed movement direction.

Isolation and characterization of complementary DNA clones for genes overexpressed in chemically induced rat hepatomas.

In order to characterize the genes overexpressed in an hepatoma cell line, the HTC cells, and in diethylnitrosamine induced solid hepatomas, we constructed a complementary DNA library from HTC cells and performed differential screening with probes from HTC cells, from malignant nodules obtained 70 weeks after the carcinogen treatment, and from hepatocytes from normal rat liver. Eight clones corresponding to messenger RNAs (mRNAs) much more expressed in hepatomas than in hepatocytes from normal liver were isolated. Three, clones pHT 71, pHT 13, and pHT 26, were further analyzed by the study of their corresponding transcripts in hepatocytes from regenerating liver and in the hepatocytes from the nontumorous parts of the liver.

A note on accepting the null hypothesis: problems with respect to the mass-spring and pulse-step models of movement control.

Models are sometimes developed on the premise that there are no differences between two or more conditions regardless of experimental manipulation. This article argues that unless a very sensitive experiment (or series of experiments) was conducted, such conclusions are often premature. Design and statistical factors such as alpha level, variability, sample size, and treatment effect are all determinants of the sensitivity of the experiment.

Expression of c-fos oncogene during hepatocarcinogenesis, liver regeneration and in synchronized HTC cells.

We have studied the expression of c-fos gene in rat hepatoma induced by DENA. An increase of c-fos mRNA concentration was observed after 8 days, but the maximal 5- to 6-fold increase was observed after 70 weeks. This increase was found in perinodular hepatocytes as well as in cancer nodules.

Electromyographic patterns accompanying isokinetic exercise under varying speed and sequencing conditions.

The purposes of this study were: a) to investigate electromyographic patterns accompanying isokinetic exercise under varying speed and sequencing conditions, and b) to investigate the role of antagonist coactivation under these same conditions. Five adult males performed maximal knee extensions and flexions on a modified Orthotron isokinetic dynamometer. Tests were done at four speeds (100-400 degrees/sec) and under two counterbalanced conditions: extension followed by flexion (E/F) and flexion followed by extension (F/E).

Correlated increase of the expression of the c-ras genes in chemically induced hepatocarcinomas.

The expression of the c-Ha-ras, the c-Ki-ras and the N-ras genes was measured by the dot blot technique in rat liver tumors induced by a short diethylnitrosamine (DENA) treatment and in the surrounding liver cells. A 2 to 25 times higher level of transcript was found as well in the surrounding cells, as in the tumor cells, as compared to the level in hepatocytes. In addition the increase of expression was parallel for the three ras genes.

Systematic search for 1 alpha,25-dihydroxy-vitamin D3 receptors in human breast carcinomas.

We looked systematically for the presence of receptor like binding sites for 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) in the cytosol from 22 breast cancers. Cytosols were centrifuged on 5-20% sucrose gradients after labeling with tritiated 1,25 (OH)2D3 (3H-1,25(OH)2D3 or 25-hydroxyvitamin D3 (25(OH)D3 alone or in the presence of a large excess of these unlabeled sterols. Binding sites for 1,25 (OH)2D3 migrating in the 3.

[Primary exocrine pancreatic insufficiency in the adult. Presentation of a case].

The authors report the case of a 37-year-old female complaining of chronic diarrhea since childhood. She had gross steatorrhea and azotorrhea . Pancreatic function tests using secretin and cholecystokinin-pancreozymin stimulation, and analysis of pure pancreatic juice collected under secretin stimulation proved exocrine pancreatic insufficiency.