Showing papers by "University of Puerto Rico, Medical Sciences Campus published in 1989"

Free-ranging Cayo Santiago rhesus monkeys (Macaca mulatta): I. Body size, proportion, and allometry.

Abstract: This paper presents comprehensive baseline data on body size and proportion of 661 (315 male, 346 female) free-ranging Cayo Santiago rhesus monkeys (Macaca mulatta) ranging in age from 24 hours to 25 years. All animals were born and raised in the free-ranging colony on Cayo Santiago, and exact ages were known for all. Tabular data from this cross-sectional study are provided to enable comparisons with data from laboratory, wild, and other captive populations of rhesus monkeys, as well as with other species. Despite the extensive literature on rhesus monkey behavior and biology, to date published accounts of its morphometrics have been limited to only a few measurements from animals of unknown age, small sample sizes, or caged colonies. Results of this study showed a distinct intraspecific pattern for body proportions throughout the life cycle. Relative linear increases in overall body proportions of maturing animals appeared to be from greatest to least in the trunk, hindlimb, and forelimb, respectively. Within the limbs, allometric scaling appeared to be fastest in the proximal segment and slowest in the distal segment. Males and females differed in the duration of growth, and gender dimorphism was associated primarily with differences in size rather than proportion. Although the primary purpose of this paper is to present numerical data on the Cayo Santiago colony, the results are compared with previous studies of both laboratory and free-ranging rhesus monkeys.

Facilitation of voltage-gated ion channels in frog neuroglia by nerve impulses

Abstract: THE functions of glial cells in the nervous system are not well defined, with the exception of myelin production by oligoden-drocytes1, uptake of amino-acid synaptic transmitters2, and a contribution to extracellular potassium homeostasis3–5. Neuroglia have receptors for neurotransmitters6,7 which may be involved in neuron-glia interactions. Recent studies have demonstrated voltage-gated ion channels in glial membranes8–12. In a study of the optic nerve of the frog, small areas of the surface were examined with the loose patch-clamp method13,14, and voltage-gated Na+ and K+ channels, presumably located in the membranes of the astrocytes forming the glia limitans, were identified15,16. We now report that nerve impulses in the axons of the frog optic nerve transiently alter the properties of the voltage-dependent membrane channels of the surface glial cells (astrocytes), a demonstration of a new form of neuron-glia interaction.

Chloride enters glial cells and photoreceptors in response to light stimulation in the retina of the honey bee drone.

Abstract: Double-barrelled ion-selective microelectrodes were used to measure free [Cl−] in photoreceptors, extracellular space, and glial cells in superfused slices of drone retina. Tests indicated that with normal superfusate the intracellular electrode signal was due essentially to Cl− and not to some other interfering anion. The results indicate that Cl− is more concentrated in both photoreceptors and glial cells than would be predicted for a passive electrochemical distribution. When the photoreceptors were stimulated by a standard train of 20 ms flashes, 1/s for 90 s, their intracellular free [Cl−] (Cli) rose by 8 ± 1 mM. At the end of stimulation Cli usually continued to rise for up to a further 2 min and then returned toward the baseline over about 10 min. During light stimulation Cli in the glia rose. The magnitude of the increase was 5.1 ± 0.4 mM, about half the increase in Ki. In some extracellular recording sites, light stimulation caused [Cl−] to increase and in others to decrease. The mean change was –0.7 mM, SD 6.5 mM. The Cl− that entered the photoreceptors and the glia was presumably made available by the shrinking of the extracellular space. When the cells were depolarized by increasing [K+] in the superfusate from 7.5 mM to 18 mM, Cli increased. The half-time of the change in Cli was longer than the half-time of the depolarization by 10–30 s in the glia and 50–250s in the photoreceptors. During superfusion with 0 Cl− Ringer's solution, the light-induced rise in extracellular [K+] was greater by a factor of 1.4–2.7, and the clearance after the end of the stimulation was slower. The rate of increase in glial Ki during light stimulation fell; the rate of increase of glial Ki caused by superfusion with raised [K+] (in the absence of Cl−) fell more. We conclude that when extracellular [K+] is increased, entry of Cl− into the glia is necessary for part, but not all, of the net uptake of K+. During light stimulation, the observed movement of Cl− into glia contributes to homeostasis of extracellular [K+], and the cell swelling associated with movement of Cl− into both glia and photoreceptors contributes to homeostasis of extracellular [Na+].

Free-ranging Cayo Santiago rhesus monkeys (Macaca mulatta): II. Passive joint mobility.

Abstract: Recent studies on the effects of caging on joint mobility and the correlations between joint mobility and use of the extremities have pointed out the need for baseline values that are readily available in the literature. This report provides normative data on the passive mobility of the major joints of free-ranging Cayo Santiago rhesus monkeys (Macaca mulatta). The sample in this cross-sectional study is large (661 animals including 315 males, 346 females), and it spans the entire age spectrum (24 hours to 25 years) of the population. Included are data on motion in the sagittal plane at six joints: shoulder, elbow, wrist, hip, knee, and ankle. Results indicated that passive joint mobility changes in a nonlinear fashion throughout the life cycle. The apparent rapid decline in mobility from birth through puberty parallels rapid changes in body size and proportions in young animals. Joint mobility is relatively stable in prime-age adults, whereas it is generally more restricted in older monkeys. Both genders follow a similar pattern, but timing differs somewhat. Although the primary purpose of this paper is to present numerical data on the Cayo Santiago population, the results are compared with previous, more limited studies of both captive and free-ranging rhesus macaques.

Parasites of free-ranging Cayo Santiago macaques after 46 years of isolation.

Abstract: Three hundred and thirty seven Macaca mulatta from a population that had been isolated on a small island off the coast of Puerto Rico for 46 years were examined for parasites. Anatrichosoma cynamolgi (26%), Strongyloides fuelleborni (54%); Trichuris trichiura (23%); and Balantidium coli (2%) were detected. Toxoplasma antibodies were found in 10% of the sera examined. Milk was examined for Stronglyloides, and blood was examined for microfilariae and protozoa, but no parasites were found in these specimens. The animals in this colony harbored intestinal parasites but were in excellent physical condition, with a high reproductive rate and a low mortality rate. It is concluded that the presence of intestinal and tissue parasites has little measurable effect on the overall health of rhesus in this free-ranging environment.

Role of Glial Cells in the Control of the Neuronal Microenvironment

Abstract: There is increasing evidence that neuroglia have a functional role in the homeostasis of the fluid bathing central neurons with regard to ions and small molecules. The microenvironment of neurons in the central nervous system is the system of narrow extracellular clefts, 20–30 nm wide, separating neurons from each other and from glial cells. The glial membranes constitute an immense surface area for exchange. The clefts are in diffusion equilibrium with the bulk of the cerebrospinal fluid as well as the space around the capillary endothelial cells. In most species the ring of endothelial cells held together by tight junctions constitutes the blood- brain- barrier (Cserr, 1986). A striking feature of this anatomical arrangement is that with rare exception, for example the nerve terminals of neurosecretory cells, neurons themselves are always separated from the CSF and extracapillary space by neuroglia. It was this observation which led Golgi in 1885 to suggest that glial cells controlled the flow of materials to and from the neurons. Subsequently, Lugaro, in 1907, postulated that glial cells exchanged substances with the extracellular fluid and thereby regulated the neuronal microenvironment (see reviews by Kuffler and Nicholls, 1966? Somjen, 1988).

Positive Modulators of Acetylcholine Receptor: Differences Between Skeletal Muscle and Electric Organ

Abstract: Synaptic receptors are regulated by allosteric modulators which may increase or decrease their response to agonists. For the nicotinic cholinergic receptor (AChR) very few positive modulators have been reported, although a number of allosteric inhibitors are known. This paper reviews work in which we have described two compounds that seem to act as positive modulators of muscle AChR, but have no effect on the AChRs present in membrane vesicles from Torpedo californica electric organ (Escalona de Motta and del Castillo, 1977; del Castillo et al., 1985; Eterovic et al., 1981; Eterovic et al. submitted to J Receptor Res).