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Biomedical subjects

M Leon

Publications and source records attributed to M Leon.

At least 163 records · Page 9Linked to original sources
PubMed1986

Elimination of persistent simian hemorrhagic fever (SHF) virus infection in patas monkeys.

Devastating epizootics of simian hemorrhagic fever (SHF) have been iatrogenically initiated in captive colonies of macaque monkeys by strains of SHF virus emanating from asymptomatic persistently infected patas monkeys. We have found that persistently infected patas monkeys can be cleared of their infection by superinfection with strains of SHF virus which cause acute infections in this species. All 20 persistently infected animals subjected to this procedure have been cleared of their infection within 3 months. These animals were shown to be virus free by the most sensitive in vitro and in vivo tests currently available and periodic tests of serum from these animals over several years have shown them to remain virus free. Superinfection has in some cases caused some adverse clinical symptoms (anorexia, lethargy, facial edema, dehydration, and mild subcutaneous hemorrhages), but with supportive care, no fatal infections have occurred. Thus, superinfection with acute strains of SHF virus is a highly effective method of eliminating persistent infection in patas monkeys.

Animals↗
PubMed1985

The effect of constant light on maternal physiology and behavior.

In contrast to previous findings in nonlactating rats, constant light does not disrupt maternal water or food intake. Mothers and pups in constant light, however, gained less weight than their counterparts in the light-dark cycle. While mothers did not differ in their total daily contact time or daily bout frequency, the distribution of the contact time was shifted in constant light. These data may be consistent with the idea that mothers maintain a free-running rhythm under such conditions.

Animals↗
PubMed1985

Thermal control of maternal contact bouts: the interbout interval.

Cooling mother rats by means of sodium salicylate injections did not curtail the intervals between maternal contact bouts. To the contrary, the interbout intervals were prolonged, suggesting that the relief from hyperthermia is a necessary but not a sufficient condition for the reinitiation of pup contact by mother rats. The ability of sodium salicylate to suppress maternal temperature suggests that pyrogenic and lactational increases in temperature may have some common feature.

Animals↗
PubMed1985

Odor familiarity alters mitral cell response in the olfactory bulb of neonatal rats.

Previous studies have shown that rat pups have an enhanced metabolic activity to familiar odors in specific glomeruli of the olfactory bulb. The present study examined extracellularly recorded mitral cell responses to odors in this glomerular region, in odor-familiar and odor-unfamiliar pups. Mitral cells in odor-familiar pups had significantly fewer excitatory and more inhibitory responses to the familiar odor than controls. There were no differences between groups in responses to a novel odor. These results demonstrate that neonatal exposure to odors selectively alters subsequent mitral cell responsiveness to that odor.

Animals↗
PubMed1985

Acromegaly and bronchial carcinoid. Effect of removal of the latter.

A patient with a long-standing history of bronchial carcinoid and acromegaly was studied. There was pituitary enlargement with an intrasellar mass (brain computed tomography scan), high basal GH levels, and abnormal GH and other pituitary hormones response to oral glucose and a combined test (LHRH, TRH, insulin). After resection of the bronchial carcinoid, basal GH was normal, GH was normally suppressed during OGTT, pituitary function was within expected normal range, and there was regression of the pituitary tumor together with clinical improvement. These data suggest that the patient's acromegaly was secondary to pituitary stimulation due to the bronchial carcinoid.

Acromegaly↗
PubMed1984

Enhanced neural response to familiar olfactory cues.

Norway rat pups have an enhanced olfactory bulb response to a familiar odor. A specific complex of glomeruli showed increased carbon-14-labeled 2-deoxy-D-glucose uptake in response to peppermint odor in 19-day-old pups exposed to peppermint on days 1 to 18 after birth, relative to control pups that had been exposed to clean air. The increased activity was not due to increased respiration of the familiar odor.

Animals↗
PubMed1984

Diurnal cycle of mother-young contact in Norway rats.

Mother rats maintained on a LD 12:12 photoperiod (lights on 0800 hrs) had longer contact bouts with their offspring during the day than during the night and maternal brain temperature peaked during the night. When the daily temperature cycle was suppressed by removal of adrenal and ovarian hormones, the daily maternal contact cycle was also suppressed. These data are consistent with a thermal model for the limitation of mother-young contact bout duration.

Adrenal Glands↗
PubMed1984

Development of olfactory bulb organization in precocial and altricial rodents.

The structural organization of the olfactory bulbs of spiny mice, Norway rats and Mongolian gerbils was followed over the course of their development. The pups of all 3 species normally begin to approach the odor of their dams at a time when their olfactory bulbs are at a similar stage of development. The data suggest that there may be a common aspect of olfactory bulb development that underlies the onset of olfactory guided approach behavior in rodents.

Animals↗
PubMed1983

Albumin, fibrinogen, prothrombin and antithrombin III variations in blood, urines and liver in rat nephrotic syndrome (Heymann nephritis).

Albumin, fibrinogen, prothrombin and antithrombin III (AT III) variations have been studied in blood, urines and liver during an experimental nephrotic syndrome in rats (Heymann nephritis). A quantitative morphometric study (light microscopy) has been performed in the liver using an immunocytochemical technique--(PAP) method--to evaluate the protein synthesis by the number of protein-containing hepatocytes. Some sections were also studied by electron microscopy. The nephrotic animals were compared with control rats. In the blood of nephrotic rats, fibrinogen and prothrombin concentrations were increased and albumin and AT III concentrations were decreased. In the urines of nephrotic rats, albumin, prothrombin and AT III were lost, but no fibrinogen. The morphometric study in the liver has shown a significantly higher number of fibrinogen and prothrombin-containing hepatocytes in nephrotic rats than in controls, suggesting an increased synthesis of these proteins; no change was observed concerning albumin and AT III between nephrotic and control animals. In electron microscopy, albumin was demonstrated in Golgi apparatus, proving that the peroxidase-positive cells are related to protein synthesis. These results show that the mechanisms of regulation of the protein synthesis during nephrotic syndrome are different from one protein to another and, particularly, that their blood level is not the only regulating factor for their synthesis.

Albumins↗
PubMed1983

Oligoclonal IgG bands in cerebrospinal fluid in various neurological diseases.

We studied the frequency of oligoclonal immunoglobulin G bands in the cerebrospinal fluid (CSF) of patients with various neurological diseases. We used a micromethod employing sodium dodecyl sulfate polyacrylamide gel electrophoresis that required only 50 microliters of unconcentrated CSF. Oligoclonal bands were detected in the CSF of 95% of the patients with multiple sclerosis, 90% with subacute sclerosing panencephalitis, and 100% with herpes simplex encephalitis, but less frequently in other central nervous system infections. No oligoclonal bands were detected in the CSF of patients with Parkinson, Huntington, Creutzfeldt-Jakob, or herniated disc diseases. Bands were detected in some patients with Alzheimer disease, cerebrovascular accident, idiopathic vertigo, idiopathic seizures, amyotrophic lateral sclerosis, polyneuropathy, and central nervous system glioma. Patients with other conditions infrequently had positive bands. The determination of oligoclonal bands is a useful aid in the diagnosis of multiple sclerosis, subacute sclerosing panencephalitis, and herpes simplex encephalitis. The presence of oligoclonal bands indicates an immunological response but is not diagnostic for a particular condition.

Central Nervous System Diseases↗
PubMed1983

Determinants of mother-young contact in Norway rats.

Rat dams choose to care for their pups in a relatively warm area, apparently because they have an elevated thermal set point for the regulation of their body temperature. Since the duration of their contact bouts with their pups is limited by an acute hyperthermia that they experience while on the pups, their choice limits the time that they can spend with their pups. When dams could choose the temperature at which they cared for their young they spent only about half the time in contact with their offspring as did dams caring for their pups at the ambient temperature of the laboratory. We conclude that rat dams do not attempt to maximize the duration of their contact bouts with their offspring. Dams also do not attempt to minimize the amount of time that they spend away from their offspring. The duration of the intervals between contact bouts was influenced by the ability of the dams to dissipate the heat gained during the contact bout with the pups. Again, dams did not seek out a cool area in which to spend their interbout intervals, preferring to remain in relatively warm areas. Their thermal preference facilitated the retention of their body heat and prolongation of the interbout intervals. Dams may return to the nest periodically for brief bouts during which the state of the pups is monitored. Pups were found to play both passive and active roles in modulating the overall pattern of maternal contact, for dams maintained contact with pups if the pups were cool, but failure to attach to the nipples soon after contact was established frequently led to rapid bout termination, particularly with warm pups. Contact is maintained if the pups are cool or if they attach to the nipples. Finally, it was found that pups could actively curtail interbout intervals by emitting ultrasonic vocalizations.

Animals↗