Experimental protein malnutrition during gestation and breeding performance of squirrel monkeys,Saimiri sciureus

The report summarizes our four year experience with the breeding of squirrel monkeys, a New World species used widely in experimental research. Breeding squirrel monkeys in captivity has hitherto been considered capricious, with success in most instances not exceeding 50%. By a combination of hand picking the animals, housing in a harem-type situation with one male to several females, and sound nutrition, a success rate of 85–91% live births to number of pregnancies has been achieved. The rate of stillbirths and abortions in the group maintained on a well-balanced diet did not exceed 10% of the total pregnancies. This compares favorably with any successful breeding program with Old World monkeys, whose reproductive physiology is relatively well understood. It is clear from our studies that adequate quantities of proteins are essential for optimum reproduction. Among the pregnant animals maintained on a diet containing about 50% of their normal requirements of protein (8% calories from a protein source), the incidence of abortions increases significantly. In this group, the rate of abortions to total pregnancies ranges from 40.5 to 61.5%. The females maintained on a protein deficient diet during pregnancy are so protein hungry that an extruded fetus is a welcome food and no time is lost in devouring all of the placenta and the fetus. This type of cannibalism has never been observed among the mothers maintained on a high protein regimen.     

Experimental protein malnutrition in squirrel monkeys: cytochemical interaction of nucleolus and cytoplasm in the anterior horn cells of the spinal cord of Saimiri sciureus.

Nuecleolo-cytoplasmic relationships have been studied using histochemical techniques in the spinal cord of healthy neonates compared with those born to mothers malnourished through most of the gestation period, and healthy and severely protein-malnourished young adult squirrel monkeys. Formaldehyde-fixed as well as fresh frozen tissues were used for histological study and for histochemical techniques to demonstrate lipids, carbohydrates, nucleic acids and enzymes of various metabolic cycles. Changes in the neuronal cytoplasm of the low protein animals appear to be related to impaired protein metabolism and energy transport. The nucleolus reacts to cytoplasmic changes by enlarging its size and by active synthesis of secretion of nucleolar material, which is then passed into the cytoplasm through an evagination of the nuclear envelope. The greater the degree of chromatolysis in the cytoplasm, the more active the nucleolus appears to be in terms of its enlarged size and transfer of secretion products into the cytoplasm. It is believed that the perinuclear accumulation of secretion products in the neuronal cytoplasm of the protein-deficient animals has its origin in the nucleolus. Such an accumulation in the severely malnourished animals appears to be a compensatory mechanism for the increased cytoplasmic catabolism and loss of ribonucleoprotein material in order to facilitate additional protein synthesis for cell survival.     

Ascending central canal dilation and progressive ependymal disruption in a contusion model of rodent chronic spinal cord injury

Background  

Chronic spinal cord injury (SCI) can lead to an insidious decline in motor and sensory function in individuals even years after the initial injury and is accompanied by a slow and progressive cytoarchitectural destruction. At present, no pathological mechanisms satisfactorily explain the ongoing degeneration.     

Experimental protein malnutrition in squirrel monkeys: reaction of the nissl substance in the motor neurons of the spinal cord

Summary Experimental protein malnutrition was induced in juvenile squirrel monkeys by feeding them synthetic diets which contained 2% protein for a period of 15 weeks. Along with their controls who were fed 25% protein food and laboratory monkey chow, groups of monkeys were sacrificed at nine, 11, 13, and 15 weeks of feeding schedule. The spinal cords were stained with chromalum-gallocyanin, PAS, Trichrome Masson's method and Alcian Blue. The neurons and the surrounding glial cells showed significant cytoohemical changes in different groups of the malnourished animals. The motor neurons of the spinal cord showed a varying but dramatic reaction to protein deficiency, which reflects a profound physiological distortion. These observations have been discussed in relation to probable functional derangement under the influence of protein deficiency.     

Immunohistochemical localization of basic fibroblast growth factor in ependymal cells of the rat lateral and third ventricles.

The presence of basic fibroblast growth factor (bFGF) in the third and the lateral ventricular ependyma of the rat has been investigated under the light microscope using a polyclonal antibody against bFGF, through the unlabelled peroxidase-antiperoxidase procedure; bFGF-immunoreactivity (bFGF-IR) is observed in the entire ependymal cell layer of ventricles. Also ependymal tanycytes within the inferior portion of the wall and floor of the third ventricle show bFGF-IR. Tanycytic processes are in close contact with hypothalamic capillaries. The present study strongly suggests that brain ependymal bFGF plays unidentified roles unrelated to its angiogenic or mitogenic capacities.     

Loss of protein structure stability as a major causative factor in monogenic disease

The most common cause of monogenic disease is a single base DNA variant resulting in an amino acid substitution. In a previous study, we observed that a high fraction of these substitutions appear to result in reduction of stability of the corresponding protein structure. We have now investigated this phenomenon more fully. A set of structural effects, such as reduction in hydrophobic area, overpacking, backbone strain, and loss of electrostatic interactions, is used to represent the impact of single residue mutations on protein stability. A support vector machine (SVM) was trained on a set of mutations causative of disease, and a control set of non-disease causing mutations. In jack-knifed testing, the method identifies 74% of disease mutations, with a false positive rate of 15%. Evaluation of a set of in vitro mutagenesis data with the SVM established that the majority of disease mutations affect protein stability by 1 to 3 kcal/mol. The method's effective distinction between disease and non-disease variants, strongly supports the hypothesis that loss of protein stability is a major factor contributing to monogenic disease.     

Intranuclear microfilament bundles in the ependymal cells of the third ventricle of the rat

Summary Intranuclear microfilament bundles were observed in ependymal cells of the third ventricle of the rat. They appeared as single, cylindricallyshaped fibrillar bands up to 4.9 m in length. In cross sections of bundles, the microfilaments exhibited an apparently regular arrangement. They were separated by a distance of 4 to 5 nm, measuring approximately 11 nm from centre to centre. One bundle consisted of 55 to 88 microfilaments. The intranuclear bundles terminated at the inner membrane of the nucleus. They exhibited close spatial relationship to perinuclear chromatin, chromatin centres, intrachromatin granules and fibrillar structures. The average ratio of nuclear sections with and without bundles was 115.Research fellow of the Alexander von Humboldt FoundationThis research was partly carried out at the Department of Histology and Embryology, Academy of Medicine at Poznan, Poland, and was supported in part by a grant from the Polish Academy of Science     

Experimental protein malnutrition in primates: Cytochemical studies on the cerebellum of the squirrel monkey,Saimiri Sciureus

Synopsis The cerebellum of healthy and malnourished squirrel monkeys was studied histopathologically and cytochemically for a number of important enzymes such as phosphatases (acid and alkaline phosphatase, ATPase, thiamine pyrophosphatase), esterases (simple esterase and acetylcholinesterase), dehydrogenases (succinate, malate and isocitrate dehydrogenase, lactate dehydrogenase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase), monoamine oxidase and phosphorylase. The Purkinje cells, stellate and basket cells were found to be more sensitive to protein malnutrition compared to the other types of cells in the cerebellum. An increase in the number of dark cells with large amounts of ribonucleoprotein complex in the Purkinje cell layer of the extremely malnourished animals sacrificed after 15 weeks on a low protein diet may be significant and may reflect either an abnormal metabolic process or an interruption in the axonal transport of RNA complex. This may also be directly related to a significant reduction in the level of oxidative enzymes, especially those of the tricarboxylic acid cycle, these being the main source of energy stored in ATP. At the same time the level of lysosomal enzymes, which are responsible for the catalysis of the different degradation reactions, is greatly increased and indicates cellular catabolism. The present investigations point to the probability that the neurons adapt to the changed environment by beginning to utilize structural proteins for their basic metabolism.     

Progesterone as a predictor of cyclicity in Bolivian squirrel monkeys during the breeding season

In a squirrel monkey breeding colony, two distinct groups of females were observed during the breeding season, December through March. One had low and the other had high estradiol (E2) and progesterone (P) concentrations. The conception rate in females with high E2 and P values was 74%. However, only 25% of monkeys with low steroid concentrations became pregnant during the breeding season. This study showed that all mature females in a colony may not be cycling concurrently and that two serum P measurements obtained at four-day intervals may be utilized to detect noncycling monkeys during the breeding season.     

Experimental protein malnutrition in primates--cytochemistry of the nervous system

Experimental protein malnutrition was induced in groups of young juvenile squirrel monkeys by feeding them ad libitum diets very low in protein content, whereas a diet containing 25% protein content was fed to the control animals. Detailed cytochemical studies have clearly shown the sensitivity of the nervous system to dietary abuse. The motor neurons of the spinal cord and the Purkinje cells of the cerebellum are very sensitive to protein deficiency, and the number of oligodendroglia cells increases sharply. Gallocyanin stained preparations from the malnourished animals show significant decrease in the amount of RNA in the Purkinje cells of cerebellum and the anterior horn cells of the spinal cord. The larger neurons show prominent chromatolysis with concomitant increase in the number of oligodendrocytes surrounding such nerve cells. The different layers of the cerebellar cortex of the malnourished animals, as well as some of the neurons of the spinal cord, showed decreased activity of succinate dehydrogenase and increased levels of thiamine pyrophosphatase and lactate dehydrogenase. Although ATPase activity appeared to remain unchanged quantitatively, it showed profound disturbance in its in situ localization, especially in the mitochondrial ATPase located in the cytoplasm. The enzyme activity in the nuclear membrane appeared unchanged. These studies emphasize the importance of studying in situ changes in the anatomically heterogeneous nervous tissue, rather than of working only with biochemical methods using homogenized material.     

Rearrangement of enveloping layer cells without disruption of the epithelial permeability barrier as a factor in Fundulus epiboly

Silver nitrate staining of blastoderms of Fundulus heteroclitus gastrulae shows that the number of marginal cells of the enveloping layer (EVL) is reduced from 160 to 25 during epiboly. To determine whether this decrease in the number of marginal cells was due to ingression, cell death, or rearrangement of cells, marginal and submarginal regions of the late gastrula were observed directly by time-lapse cinemicrography. Marginal cells rearrange to occupy submarginal positions by first narrowing their boundary with the external yolk syncytial layer (E-YSL), thus becoming tapered in shape. Then, the narrowed marginal boundary retracts from the E-YSL and moves submarginally in the plane of the epithelium. Concurrently, the marginal cells on both sides come into apposition; no gap or break appears in the circum-apical continuity of the epithelial sheet. Marginal cells leave the margin of the EVL during epiboly at a rate of about six per hour. The rate of movement of the EVL cells with respect to one another is about 0.5 to 1.0 micron/min at 21 degrees C. Submarginal cells rearrange in a similar fashion. Although no protrusive activity was seen at the lateral aspects of rearranging cells, the tapering or narrowing associated with rearrangement was accompanied by formation of microfolds on their apical surfaces, and separating or recently separated submarginal cells form "flowers" of microfolds on their apices adjacent to the site of separation. Morphometric analysis shows that about half the narrowing of the margin of the EVL during epiboly is accounted for by cell rearrangement and the other half by the associated tapering and narrowing. These results suggest that epiboly of the EVL may have an active component as well as a passive one.     

Pasteurized milk as a factor in the transmission of the causative agents of yersiniosis]

From 43 (35.8%) out of 120 samples of pasteurized milk used by volunteers 182 cultures of five Yersinia species--Y. enterocolitica, biovar 1 (70.3%), Y. intermedia (18.1%), Y. frederiksenii (7.7%), Y. kristensenii (3.3%) and Y. aldovae (0.5%)--were isolated in the course of bacteriological studies carried out in 1987-1990. The isolated Yersinia cultures belonged to nonpathogenic pyraminidaze-positive serovars. Yersinia pathogenic bio/serovars (4/O3, 2/O9, 1B/O8) were not detected. No deviations from the normal state were registered in the volunteers drinking pasteurized milk, and Yersinia could be isolated from their feces only during the first 3 days following milk consumption. In 390 patients examined for the presence of Yersinia infections the isolation rate of Yersinia of biovar 1 (99.6% of the cultures) varied between 4.4% and 21.3% and correlated with the increase of the isolation rate from milk (13.6% to 53.9%). The results of the study suggest that unboiled pasteurized milk contributes to the spread of Yersinia carriership among the population.     

Autonomic innervation of the salivary glands in cebid monkeys: a histochemical study.

The autonomic innervation of the major and minor salivary glands was studied in five species of cebid monkeys using acetylcholinesterase (AChE) and catecholamine histochemistry. Catecholamine-containing and AChE-positive nerve fibres were observed in the vessels and secretory endpieces of all glands, with no apparent predominance of one type over the other. In the intralobular ducts, however, the cholinergic innervation predominates. In the major salivary and minor sublingual glands the density of the nervous supply was higher, whereas in the secondary mandibular and posterior lingual glands it was less dense. The morphological patterns of salivary gland innervation found in Cebidae are compared with those of the related family Callitrichidae.     

Autometallography used as a histochemical indicator of lysosome function in cultured cells.

The present paper suggests the autometallographic demonstration of intralysosomal silver as a sensitive tool for the detection of subtile toxic effects in cell cultures, the method is suggested to primarily detect lysosomal damage.