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Hypervitaminosis A dysmelia in rats.

Limb defects were induced in the offspring of rats by giving 200,000-800,000 i.u. per kg. vitamin A on days 10-16 of their pregnancy. The malformations were symmetrical and there was no fore or hind limb predominance but fore limb lesions tended to be more severe. As severity increased there was progressive distoproximal suppression of digital rays commencing with digits 1 and 5 then extending to digits 2 and 3. Digit 4 was affected last. Syndactyly of soft tissues and bone was a part of the process and could produce single composite digits. Deletion of digits occurred and could result from pu…

Treadmill Stepping in Newborn Rats.

The purpose of this study was to investigate the influence of treadmill belt speed on mechanically-induced (tail-pinch) and pharmacologically-induced (quipazine, a 5HT 2A agonist) stepping behavior in one-day old rats. On postnatal day 1 (P1), male rat pups were tested on one of four moving treadmill belt speeds. Stepping was induced using a tail-pinch and quipazine administration to examine real-time adaptations on belt speeds. For tail-pinch-induced stepping in the forelimbs and hindlimbs, there was a significant effect of time but not belt speed. Step cycle duration was significantly shorte…

Spontaneous rhabdomyosarcomas in Dmdmdx rats.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder primarily affecting male children and resulting in progressive degenerat … d gene on a Sprague Dawley background. Subcutaneous firm masses were noted grossly in 8 male Dmdmdx rats aged 6 to 17 months. The histologic findings were consistent with a sarcoma of skeletal muscle, with a population of small round cells in addition to spindle-shaped cells and occasional large multinucleated cells. The neoplasms were immunoreactive f …

Luteal toxicity evaluation in rats.

The corpora lutea (CL) are endocrine glands that form in the ovary after ovulation and secrete the steroid hormone, progesterone (P4). P4 pl … teal regression process, CL were almost fully regressed after four estrous cycles in Sprague-Dawley rats. P4 secretion from CL in rodents is regulated by the balance between synthesis and catabolism. In general, luteal toxicity should be evaluated by considering antemortem and postmortem data. Daily vaginal smear observations provided useful informatio …

Rats Sniff Off Toxic Air.

Breathing air is a fundamental human need, yet its safety, when challenged by various harmful or lethal substances, is often not properly guarded. For example, air toxicity is currently monitored only for a single or a limited number of known toxicants, thus failing to warn against possible hazardous air fully. Here, we discovered that, within minutes, living rats emitted distinctive profiles of volatile organic compounds (VOCs) via breath when exposed to various airborne toxicants such as endotoxin, O3, ricin, and CO2. Compared to background indoor air, when exposed to ricin or endotoxin aero…

Биология и болезни крыс

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… Globally, the Norway rat has largely displaced the black rat, probably because of the Norway rat’s larger size and aggressiveness. … Rats from a Sprague-Dawley background (such as the CD and SD stocks) and Lewis rats are generally more docile than Brown Norway or F-344 rats. …

EXPERIMENTAL PARACOCCIDIOIDOMYCOSIS IN PREGNANT RATS.

Paracoccidioidomycosis (PCM), caused by the dimorphic fungus Paracoccidioides brasiliensis (Pb), is the most prevalent systemic mycosis in Latin America. There are few reports in the literature about the disease damages during pregnancy and the consequences to the fetuses and breeding. This study evaluated the implications of PCM during pregnancy on offspring and mothers in Wistar rats. Groups of rats were submitted to systemic Pb infection, by intraperitoneal infusion, and mated 30 days after the infection date. Immediately after birth, rats and neonates were sacrificed to obtain organs for s…

Improved learning in microencephalic rats.

ABSTRACT Environmental enrichment (EE) facilitates recovery from behavioral abnormalities and spatial memory disabilities in several neurolo … ese processes. To confirm this hypothesis, male methylazoxymethanol acetate-induced microencephalic rats were exposed to EE or conventional housing after weaning; half of these rats further received intracisternal 5,7-dihydroxytryptamine on postnatal day 3, to induce long-lasting depletion of serotonin. As adults, these microencephalic rats were observ …

Sleep homeostasis in infant rats.

Homeostatic regulation is a defining characteristic of sleep but has rarely been examined in infants. This study presents an automated method of sleep deprivation in which 5-day-old rats were shocked whenever the nuchal muscle became atonic. The intensity of shock was always set at the minimal level required to maintain arousal. Deprived pups exhibited rapid increases in sleep pressure, as evidenced by increased attempts to enter sleep and subsequent increases in sensory threshold; this increased sensory threshold was not due to sensory adaptation of peripheral receptors. In addition, myocloni…

[Acute fever due to rats].

The bite of a rat can transmit diverse micro-organisms; however, the development of health measures and the improved conditions of habitability of homes have meant that the infectious diseases transmitted by the aggressions of these animals are infrequent in industrialised countries. In occasional circumstances this type of aggression can still take place, especially in depressed areas on the periphery of big cities and in uninhabited premises, this being a possibility that it is advisable to bear in mind. The case is presented of fever due to a rat bite in a patient who was attacked while cle