Motor asymmetry of the forelimbs of the rat

Preference was studied of one of the forelimbs during performance of different manipulating movements in white rats. High degree of "handedness" was observed in all studied movements. However it was not absolute--no animals performed all movements by one and the same limb. Degree and character of "handedness" were different for different movements, though the number of "righthanded" rats in most tests as a whole exceeded the number of "lefthanded" ones. The "handedness" depends on the individuality of the animal, the character of the motor task, learning and interference of different motor tasks during training.     

Analysis of respiratory neuronal activity in fetal sheep.

We developed a new method to monitor fetal medullary respiratory neurons utilizing a two-stage approach. At 129-133 days of gestation, sheep were anesthetized, and a window was placed over the area of the fourth ventricle. After a recovery period of 3-5 days, the fetus was exteriorized into a saline bath under maternal spinal anesthesia, and the head was connected rigidly to a stereotaxic frame. Microelectrodes were inserted into the area of the nucleus tractus solitarius during rapid-eye-movement sleep, and extracellular recordings of 223 respiratory neurons were analyzed: 76% were inspiratory, 9% expiratory, and 15% phase spanning, as classified by visual and computer correlation to diaphragmatic activity. More detailed analysis of 100 neurons was done to assess the respiratory component (eta 2) by use of a modification of the method developed by Orem and Dick (J. Neurophysiol, 50: 1098-1107, 1983). With use of cohorts of 25 breaths, fetal respiratory neurons were found to frequently change their phase relationship to diaphragmatic activity. The eta 2 statistic of fetal respiratory neurons was not a stable characteristic but changed over time. This could be a reflection of an immature central respiratory system before birth or the lack of major sensory inputs.     

Relationship of the DNA content in the nuclei of Amoeba proteus to the food regimen]

The relative DNA content of isolated Amoeba proteus nuclei has been measured by cytofluorometry. With the amoeba strain studied, the generation time is roughly equal to 48 hours at 25 degrees C, and with the presence of food in the medium. After the synchronous divisions, amoebae were maintained in the medium either with or without food organisms (Tetrahymena pyriformis). DNA contents in the nuclei of both the amoebae groups were measured within 4 and 48 hours after division. Before 16 hours, the nuclear DNA contents did not differ in either group. Starting from 20 hours, the DNA amount in fed amoebae exceeded that in starved animals. On the whole, the differences in DNA quantity increased by a 48th hour after division, when the nuclei of the former contained 145% DNA of the latter. The results obtained suggest that the DNA synthesis in amoeba nuclei may proceed during the whole interphase, and that during the second half of interphase the content of DNA may depend on the feeding intensity in amoebae. After refeeding the starved animals, DNA contents in their nuclei increased to reach the same level as in the constantly fed amoebae seen in the end of interphase.     

Ability of female ixodid ticks to recover from poisoning with DDT in the process of feeding]

Ability of hungary females of Ixodes persulcatus, Haemaphysalis concinna and Dermacentor silvarum to feed and lay eggs after having been exposed to different DDT doses (LD100) has been studied. The ticks heavily injuried but still mobile can feed on the host and lay eggs, i.e. to overcome the poisoning. Clutches laid by these females do not differ from control ones. Loss of mobility deprives the ticks of the ability to fed. An increase in DDT dose (LD100 X 100, experiment with I. persulcatus) does not allow the ticks to feed even if the ability to movement is preserved.     

Effect of cellularity on the sensitivity of detecting squamous lesions in liquid-based cervical cytology

OBJECTIVE: To evaluate the effect of cellularity on the sensitivity of both screening and diagnosis in a liquid-based cervical sample. STUDY DESIGN: SurePath samples (TriPath Imaging Inc., Burlington, North Carolina, U.S.A.) with known diagnoses were selected, including 18 negative, 16 low grade squamous intraepithelial lesion (LSIL) and 12 high grade squamous intraepithelial lesion (HSIL) cases. Through a serial dilution technique, samples of varying cellularity were prepared. The 275 slides were assigned random numbers and were routinely screened by 1 of 2 senior cytotechnologists, blinded to the reference diagnosis. Specimens with a screening diagnosis of atypical squamous cells of undetermined significance (ASCUS) or higher were reviewed by two pathologists, resulting in a final consensus diagnosis. Using a grid counting system, cellularity was determined for each slide. RESULTS: There was a clear demarcation in sensitivity between specimens with a cellularity of < 5,000 or > or = 5,000 squamous cells. This applied to both the sensitivity for screening and to the final consensus diagnosis. For cases with a reference diagnosis of LSIL+, at a cytotechnologist screening level of ASCUS or greater, sensitivity increased from 72.8% (< 5,000 cells) to 98.1% (> or = 5,000 cells) and for a reference diagnosis of HSIL from 85.7% to 100%, respectively. Similarly, for the consensus diagnosis, sensitivity rose from 78.5% (< 5,000 cells) to 96.6% (> or = 5,000 cells) for LSIL+ and from 82.9% to 100%, respectively, for HSIL. These differences were statistically significant (P < .001). CONCLUSION: A minimum cellularity of 5,000 squamous cells is recommended for SurePath liquid-based cervical preparations.     

Cytofluorimetric study of the glycogen content in hepatocytes of varying ploidy in adult rats]

A combined method, that allows measuring glycogen and DNA contents in one of the same cell, was applied for quantitative determination of these in mono- and binucleate hepatocytes with different ploidy obtained from adult rats. The mean glycogen content was shown to increase proportionally to the genome number within the changes of the hepatocyte ploidy from 2 to 8c.     

Effects of microinjection of vasopressin in dorsal pontine reticular structures on the gain of vestibulospinal reflexes in decerebrate cats.

1. The possibility that vasopressin (VP) acts on the dorsal pontine reticular formation (pRF) and the related medullary inhibitory reticulospinal (RS) system to control posture as well as the vestibulospinal reflexes has been investigated by injecting small doses of VP in precollicular decerebrate cats. 2. Unilateral microinjection of VP (0.25 microliters at the concentration of 10(-11) micrograms/microliters saline) in the pRF decreased the extensor rigidity in the ipsilateral limbs, while that of the contralateral limbs either decreased or increased. The same injection also produced a moderate or a prominent increase in gain of the multiunit EMG responses of the ipsilateral triceps brachii to roll tilt of the animal (t-test, P less than 0.001 for either group of responses). In the first instance the response gain of the contralateral triceps brachii to animal tilt slightly increased, while the pattern of response remained always of the alpha-type, as shown for the ipsilateral responses (increased EMG activity during ipsilateral tilt and decreased activity during contralateral tilt). In the second instance, however, the response gain showed only slight changes, while the pattern of responses reversed from the alpha- to the beta-type. These findings occurred 5-20 min after the injection, fully developed within 30-60 min and disappeared in about 2-3 hours. 3. The structures responsible for the postural and reflex changes described above were located in the dorsal pontine tegmental region immediately ventral to the LC, and included the peri-LC alpha and the surrounding dorsal pRF. The induced effects depended upon the injected neuropeptide, since previous injection of an equal volume of saline stained by the pontamine sky blue dye into the same dorsal pontine area was ineffective. 4. We postulated that VP exerts an excitatory influence on ipsilateral dorsal pRF neurons. The increased discharge of these neurons and the related medullary inhibitory RS neurons would lead to a decreased postural activity in the ipsilateral limbs. However, since these inhibitory RS neurons fire out of phase with respect to the excitatory vestibulospinal neurons, it appears that the higher the firing rate of the RS neurons in the animal at rest, the greater the disinhibition that affects the limb extensor motoneurons during ipsilateral tilt. These motoneurons would then respond more efficiently to the same excitatory volleys elicited by given parameters of stimulation, thus leading to an increased gain of the EMG responses.(ABSTRACT TRUNCATED AT 400 WORDS)