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R Aguilar

Publications and source records attributed to R Aguilar.

At least 37 records · Page 2Linked to original sources
PubMed2000

Luteinizing hormone secretion elicited in a ligand-independent activation of progesterone receptor manner at pituitary level in the rat: differential effect of two selective estrogen receptor modulators.

In the absence of progesterone, RU486 reduced basal and luteinizing hormone-releasing hormone (LHRH)-stimulated LH secretion in pituitaries from proestrous rats, a fact which evidences a ligand-independent activation of progesterone receptors (LIAPR) at pituitary level. This was also observed in pituitaries from rats treated with tamoxifen, and absent in glands from either ovariectomized or raloxifene-treated animals. Both ovariectomy or raloxifene treatment reduced the stimulatory effect of LHRH on LH secretion, while tamoxifen induced an even higher response. Prolactin (PRL) secretion was unaffected by either RU486 or LHRH, nor it was influenced by ovariectomy or raloxifene treatment. However, treatment with tamoxifen elevated PRL in all groups. These findings indicate that LIAPR is an estrogen-dependent phenomenon at the anterior pituitary of the female rat, and that tamoxifen and raloxifene present agonist and antagonist estrogen activity, respectively, at this level.

Animals↗
PubMed2000

Differential effects of cohort removal stress on the acoustic startle response of the Roman/Verh rat strains.

Male and female rats of the inbred Roman/Verh strains, which have been psychogenetically selected and bred for good (RHA-I/Verh) and extremely poor (RLA-I/Verh) two-way avoidance acquisition, were evaluated in an acoustic startle response test. One half of the rats of each strain and sex were previously subjected to 30 min of isolation by removal of their cage partners ("cohort removal"). During the testing session each animal received 40 acoustic stimuli at interstimulus intervals of 30 seconds. The hyperemotional RLA-I/Verh rats (especially the males) showed stronger acoustic startle responses than did their RHA-I/Verh counterparts. Startle amplitudes of the RLA-I/Verh males were further enhanced by the stress of 30 min isolation, whereas cohort removal did not significantly affect startle response amplitudes in RHA-I/Verh rats of either sex or in females of the RLA-I/Verh strain.

Acoustic Stimulation↗
PubMed2000

The in vitro inhibitory action of antiprogestin RU486 on LH and FSH secretion in the absence of progesterone in rats is estrogen-dependent.

Previous in vivo findings show that in the virtual absence of progesterone (P), the antiprogestin RU486 reduces LH and FSH secretion in proestrous rats, indicating that activation of P receptor (PR) can occur in the absence of the cognate ligand. The present study investigates, in vitro, whether or not the inhibitory effect of antiprogestin RU486 on gonadotropin secretion in the absence of P is estrous cycle dependent, and whether its specific expression in proestrus mirrors the high estrogen (E2) background. In the first experiment we investigated the effect of RU486 (10 nM) and/or LHRH (10 nM) on LH and FSH secretion in incubated pituitaries collected on each day of the estrous cycle of the rat. In the second experiment, we determined the effect of RU486 and/or LHRH on preovulatory LH and FSH release by pituitaries from female rats that were ovariectomized (OVX), treated with the antiestrogen LY117018-HCL (Eli Lilly & Co.), or injected with 20 micrograms of estradiol benzoate (EB). The third experiment investigated the effect of RU486 and/or LHRH on LH and FSH release by pituitaries collected from intact or EB-treated (0.1 mg/kg over three consecutive days) male rats. RU486 reduced both basal and LHRH-stimulated LH and FSH secretion in proestrous pituitaries from normal 4-day cyclic rats. By contrast, in diestrous pituitaries, RU486 increased both parameters of LH secretion but was without effect on FSH release. RU486 was also without effect in pituitaries collected from rats in estrus or metestrus, or from OVX or antiestrogen-treated rats. Moreover, EB injection or treatment induced the full inhibitory effect of RU486 in pituitaries from female and male rats, respectively. The above results suggested that P occupancy of the receptor is not required for the formation or function of the active receptor and hence for preovulatory LH and FSH secretion, and that this form of PR activation at pituitary level is E2-dependent and not genetically determined.

Animals↗
PubMed2000

Progesterone on an oestrogen background enhances prolactin-induced apoptosis in regressing corpora lutea in the cyclic rat: possible involvement of luteal endothelial cell progesterone receptors.

Preovulatory surges of both prolactin (PRL) and progesterone have been suggested to be necessary for the induction of apoptosis in the regressing corpus luteum of the cyclic rat. The aim of these experiments was to study whether the administration of PRL and/or progesterone on the morning of pro-oestrus reproduces the regressive changes that happen in the cyclic corpus luteum (CL) during the transition from pro-oestrus to oestrus, and to analyse the temporal relationships between two characteristic features of structural luteolysis (luteal cell apoptosis and accumulation of macrophages). Cyclic rats (treated at 0900 h with an LHRH antagonist to block LH secretion) were injected at 1000 h with PRL and progesterone and killed at 0, 30, 60, 90 and 180 min after treatment. The number of apoptotic cells increased progressively from 60 min after treatment onward in hormone-treated rats, whereas the number of macrophages did not change throughout the period of time considered. Rats injected with PRL plus progesterone showed significantly greater numbers of apoptotic cells than those injected with PRL alone. The luteolytic effects of progesterone were in keeping with the presence of luteal endothelial cells showing progesterone receptor (PR) immunoreactivity in pro-oestrus. Treatment of rats during dioestrus and pro-oestrus with the specific antioestrogens LY117018 and RU58668 decreased the luteolytic effects of PRL and progesterone and the number of luteal endothelial cells immunostained for PR. These results strongly suggest that the preovulatory PRL surge and the preovulatory increase in progesterone together trigger structural regression of the corpus luteum. This seems to be dependent on oestrogen-driven cyclic changes in PRs in luteal endothelial cells.

Animals↗
PubMed2000

Reduced oxygen diffusion across the shell of Gray gull (Larus modestus) eggs.

Gray gulls, Larus modestus, nest 1500 m above sea level in northern Chile's Atacama Desert, one of the driest in the world. Their eggshell gas permeability, one third of that found in other Larus species, is an adaptation that reduces water loss, but at the expense of oxygen diffusion into the air cell with resultant hypoxia and reduced metabolic rate. This contrasts with characteristics found in birds nesting at very high altitudes where oxygen diffusion across the egg shell is maximized at the expense of water conservation. The oxygen consumption (MO2) of Larus modestus is 66% that of Larus argentatus; the oxygen conductance (GO2) is equivalent to 48% of that obtained in 5 other bird species. The oxygen partial pressure (PAO2) in the air chamber of Larus modestus (84 Torr) is lower than that of 10 other bird species whose average (PAO2) is 106 Torr. The CO2 partial pressure (PACO2) in the air chamber of Larus modestus is 68 Torr, a higher value than that found in 9 other bird species whose average (PACO2) is 39 Torr.

Adaptation, Physiological↗
PubMed2000

Butorphanol/xylazine/ketamine immobilization of free-ranging Baird's tapirs in Costa Rica.

Cardiopulmonary effects and the utility of a butorphanol/xylazine/ketamine combination were evaluated during twenty immobilizations of sixteen Baird's tapirs (Tapirus bairdii) between March 1996 and January of 1998 in Corcovado National Park (Costa Rica). The animals were attracted to a bait site and darted from tree platforms. The tapirs were estimated to weigh between 200 to 300 kg. Actual weights of three tapirs taken at later dates fell within the estimated range. A butorphanol, 48+/-1.84 (x +/- SE) mg/animal IM, and xylazine, 101+/-2.72 mg/animal IM, combination was used to immobilize the animals. In some instances, ketamine was used either IM or IV at 187+/-40.86 mg/animal to prolong the immobilization period in addition to the butorphanol/xylazine combination. Naltrexone was used IM to reverse butorphanol at 257+/-16.19 mg/animal. Either yohimbine, 34+/-0.61 or tolazoline at 12+/-10.27 mg/animal, was used to reverse xylazine. The mean time from dart impact to first visible effect was 4.63+/-0.50 min (x +/- SE). Mean time to sternal recumbency was 12.21+/-1.08 min. Mean time the tapirs were immobilized was 45.63+/-3.6 min. Mean time to return to sternal recumbency and standing in animals that received yohimbine and naltrexone was 3.16+/-1.06 and 5.33+/-1.45 min, respectively. Mean time to return to sternal recumbency and standing in animals that received tolazoline and naltrexone was 1.57+/-0.39 and 3.14+/-0.51 min, respectively. Cardiopulmonary parameters including heart rate, respiratory rate, body temperature, electrocardiogram, percent oxygen satoration, and indirect blood pressure were recorded. Arterial blood gas analysis was performed on four animals. A mild degree of hypoxemia was evidenced by low arterial oxygen saturations. Five of 14 (36%) animals measured had oxygen saturations below 90%. Bradycardia (heart rates <45 BPM) was an expected finding in 11 (55%) immobilizations. Induction, recovery and muscle relaxation of each immobilization was graded. Premature arousal, which occurred in six (30%) animals, was the only problem associated with the immobilizations. Butorphanol/xylazine is a recommended protocol for immobilization of calm, free-ranging tapirs lasting less than 30 min. Supplemental intravenous administration of ketamine is recommended for longer procedures. Nasal insufflation of oxygen is recommended.

Adrenergic alpha-Agonists↗
PubMed1999

Inbred Roman high- and low-avoidance rats: differences in anxiety, novelty-seeking, and shuttlebox behaviors.

In the present study, male inbred animals (from the 10th generation of an inbreeding program that has been carried out in parallel to that of the outbred Roman high- and low-avoidance rat lines), were compared for emotionality in different testing situations, exploratory behavior in the holeboard and two-way, active-avoidance acquisition. Compared to the inbred Roman high-avoidance (RHA-I/Verh) rats, inbred Roman low-avoidance (RLA-I-Verh) rats showed higher emotionality in the open field (reduced distance travelled and number of rearings, and increased self-grooming behavior), in the elevated plus-maze test (increased number of total and open-arm entries, reduced distance travelled in the open arms, and increased self-grooming behavior), and during the habituation period in the shuttle box (decreased number of crossings, increased self-grooming behavior and defecations). Results from the hyponeophagia test were not conclusive, probably due to the test-dependent hyperactivity shown by RHA-I/Verh rats. In the holeboard apparatus, RHA-I/Verh rats explored more than RLA-I/Verh rats, especially when novel objects were located beneath the holes. Finally, RHA-I/Verh animals rapidly acquired active, two-way (shuttlebox) avoidance, whereas RLA-I/Verh animals required four 50-trial sessions to achieve an assymptotic level of 30-40% avoidance. Thus, the behavioral patterns of the Roman inbred strains were very similar to those previously reported for the RHA/Verh outbred lines. Differences in locomotor activity, exploratory, and self-grooming behavior were actually greater between the inbred strains than between the outbred lines. Differences in defecation, however, although still significant, were not so pronounced as those noted previously at this laboratory with the outbred lines.

Animals↗
PubMed1999

Biochemistry and pharmacology of rabbit cardiac growth hormone (GH) receptors.

In this report we present the first in-depth description of the biochemical and pharmacological properties of rabbit cardiac GH receptors. The apparent M(r)'s of the [125I]human (h) GH-receptor complexes were 380, 205, 90, 62, 52 and 38 kDa as demonstrated by an autoradiograph of affinity-labelled cardiac GH receptors separated under non-reducing conditions by SDS PAGE. The [125I]hGH-cardiac GH receptor complexes were disulfide-linked since the M(r)s of the complexes diminished to 170, 116, 97, 71, 45 and 38 kDa under reducing conditions, indicating the presence of multiple receptors, receptor-associated macromolecules or receptor and ligand in various ratios. The pharmacology of cardiac GH receptors is not typical of GH receptors present in other tissues. In radio receptor assays, both bovine GH and ovine prolactin were 50-fold and 100-fold less potent, respectively, than unlabelled hGH, in blocking the binding of [125I]hGH to cardiac binding sites and were, therefore, extremely weak antagonists. Similarly, neither bovine GH nor ovine prolactin blocked the [125I]hGH affinity-labelling of cardiac GH receptors compared to equivalent doses of unlabelled hGH. Parameters which characterize the kinetics for the association, dissociation and equilibrium binding of [125I]hGH to cardiac GH receptors were ascertained. Association kinetics for the binding of [125I]hGH to heart GH receptors exhibited a maximum specific binding at 17 h and 25 degrees C. The association of [125I]hGH to heart GH receptors was reversible with approximately 15 h required for half of the specifically bound [125I]hGH to dissociate. The coupling of [125I]hGH to heart GH receptors was optimum at pH 6 and the strength of the equilibrium binding, as measured by the ED50, was approximately 2 ng/ml. These data indicate that the cardiac GH receptors are pharmacologically distinct and that there is a M(r) heterogeneity in the [125I]hGH receptor complexes.

Animals↗
PubMed1999

Antiprogestins RU486 and ZK299 suppress basal and LHRH-stimulated FSH and LH secretion at pituitary level in the rat in an oestrous cycle stage-dependent manner.

We have previously shown that administration of antiprogestin (AP) type II RU486 to ovariectomized (OVX) rats on the morning of pro-oestrus decreases the magnitude of preovulatory gonadotrophin surge. This suggests that the effect of RU486 on LHRH-dependent gonadotrophin release may be independent of its ability to block progesterone actions. The aim of the present research was to study the possible site of RU486 action and to determine whether the gonadotrophin suppressive effect of APs RU486 and ZK299 is dependent on the oestrogen background. Intact or OVX rats in the morning of pro-oestrus were injected s.c. with 4 mg of RU486 or ZK299 (AP type I) at 0900 h on pro-oestrus. At 1830 h, serum concentration of FSH and LH and median eminence (ME) content of LHRH were determined. In the second experiment, the effect of RU486 and ZK299 on pituitary responsiveness to LHRH (100 ng, i.p.) and ME content of LHRH at 1830 h pentobarbital-blocked intact or OVX rats was evaluated. In the last study, the anterior pituitary release of FSH and LH from pro-oestrus or metoestrus donors incubated with or without LHRH (1, 10 or 100 nM) in the presence or absence of APs (20 nM) was evaluated. Both APs reduced serum FSH and LH levels at 1830 h on pro-oestrus in intact and OVX rats. The suppressive effect on gonadotrophin release brought about by AP treatment was also evidenced in PB-blocked intact and OVX rats. This suggested that the inhibitory effect of APs occurred, at least in part, at pituitary level. Furthermore, in the absence of the natural ligand, APs significantly reduced basal and LHRH-stimulated FSH and LH release from pro-oestrous but not from metoestrus pituitaries. In conclusion, these experiments have shown, both 'in vivo' and 'in vitro', that APs RU486 and ZK299 have suppressive effects at pituitary level on basal and LHRH-stimulated FSH and LH secretion, regardless of their antiprogestagenic activity, in pro-oestrus but not in metoestrus.

Analysis of Variance↗
PubMed1999

Genetically engineered Mengo virus vaccination of multiple captive wildlife species.

Encephalomyocarditis virus (EMCV), has caused the deaths of many species of animals in zoological parks and research institutions. The Audubon Park Zoo, (New Orleans, Louisiana, USA) attempted vaccination of several species with a killed EMCV vaccine with mixed results. This paper reports an attempt at vaccination against EMCV using a genetically engineered, live attenuated Mengo virus (vMC0) at the Audubon Park Zoo and Miami Metro Zoo, (Miami, Florida, USA) from December 1996 to June 1997. Several species of animals were vaccinated with vMC0, which is serologically indistinguishable from the field strain of EMCV. Serum samples were taken at the time of vaccination and again 21 days later, then submitted for serum neutralization titers against EMCV. The vaccinate species included red capped mangebey (Cercocebus torquatus), colobus (Colobus guereza), angolan colobus (Colobus angolensis), ruffed lemur (Lemur variegatus ruber and Lemur variegatus variegatus), back lemur (Lemur macaco), ring-tailed lemur (Lemur catta), siamang (Hylobates syndactylus), diana guenon (Cercopithicus diana), spider monkey (Ateles geoffroyi), common marmoset (Callithrix jacchus), talapoin monkey (Cercopithecus talapoin), Brazilian tapir (Tapirus terrestris), Baird's tapir (Tapirus bairdii), Malayan tapir (Tapirus indicus), dromedary camel (Camelus dromedarius), bactrian camel (Camelus bactrianus), gerenuk (Litocranius walleri), guanaco (Lama glama guanicoe), black duiker (Cephalophus niger), Vietnamese potbellied pig (Sus scrofa), babirusa (Babyrousa babyrussa), collard peccary (Tayass tajacu), and African crested porcupine (Hystrix africaeaustralis). The vaccine response was variable, with high virus neutralizing antibody titer responses in some primate species and mixed to poor responses for other species. No ill effects were seen with vaccination.

Animals↗
PubMed1999

Measles epidemiology and outbreak response immunization in a rural community in Peru.

Only limited data are available on the impact of measles outbreak response immunization (ORI) in developing countries. We conducted a community survey in Espindola, a rural border community in northern Peru, following a measles outbreak and subsequent ORI to study the epidemiology and impact of the outbreak and to evaluate the costs and benefits of measles ORI. During the outbreak, 150 of the 553 Espindola residents developed clinical cases of measles. Adults accounted for 44.0% of cases, and were frequently identified as primary cases. The attack rate among all susceptible people was 45.5% and was highest (61.2%) for the 16-20 year age group. Among adults, significant risk factors for developing measles included being aged 16-20 years (relative risk [RR] = 3.06, 95% CI = 2.08, 4.49) and being male (RR = 1.73, 95% CI = 1.11, 2.71). Among serologically confirmed cases, 60.7% developed diarrhoea and 32.1% pneumonia. The overall case-fatality rate was 3.3%, but reached 19.1% in the 0-23-month age group. Failure to reach children through either routine immunization or national campaigns made this community vulnerable to the severe and extensive impact of measles virus importation. The ORI campaign targeted non-measles case children aged 6 months to 15 years, regardless of their previous immunization status, and was effective in terminating this measles outbreak and in preventing morbidity, loss of livelihood and death despite the involvement of large numbers of adults in measles transmission. The last measles case occurred within 3 weeks of completing ORI. The ORI campaign, which would have cost approximately US$ 3000 in 1998, saved as many as 1155 person-days of work among 77 adults, prevented an estimated 87 cases of diarrhoea and 46 cases of pneumonia, and averted 5 deaths.

Adolescent↗
PubMed1998

A financial analysis of treatment strategies for Trypanosoma evansi in the Brazilian Pantanal.

The Brazilian Pantanal is a 138,000 km2 tropical seasonal wetland located in the center of South America bordering Bolivia and Paraguay. The Pantanal contains approximately 1100 cattle ranches, 3 million cattle, 49,000 horses and a unique diversity of wildlife. Cattle ranching is the most important economic activity in the Pantanal. This study explores the direct financial impacts of the adoption of seven treatment strategies for the control of Trypanosoma evansi in the Brazilian Pantanal. T. evansi adversely affects the health of the horse population in the region. Horses are indispensable to the cattle ranching industry in the Pantanal. Estimated costs include risk of infection, costs of diagnosis, alternative treatments, collecting animals for treatment, and costs of animal losses. The estimated total cost of T. evansi to the Pantanal region's cattle ranchers is about US$2.4 million and 6462 horses/yr. Results indicate that one preventive and two curative treatment strategies are financially justifiable. The best available technology for the treatment of T. evansi from an economic perspective is a curative treatment employed year-round. This treatment represents an annual net benefit of more than US$2 million or US$1845/ranch and spares about 5783 horses. It represents an annual net benefit of over US$200,000 and 600 horses relative to the currently most widely adopted strategy.

Animals↗
PubMed1998

Absence of influence of prior treatment with interferon on the outcome of allogeneic bone marrow transplantation for chronic myeloid leukemia.

Timing of transplantation in the chronic phase of chronic myeloid leukemia (CML) and previous treatment with interferon remains controversial. We have tried to discover what influence pretreatment with interferon alpha (IFN-A) has on the results of allogeneic bone marrow transplantation for CML patients treated in a single institution. Fifty-one consecutive patients with chronic phase Ph-positive CML who received an allogeneic bone marrow transplantation from a HLA-identical familial donor were evaluated. Thirty had been treated with IFN-A (IFN+ group) prior to BMT and twenty-one had not (IFN- group). Both groups were homogeneous for clinical characteristics such as age, sex, previous chemotherapy, disease status, and time from diagnosis to transplant. No difference was found in neutrophil and platelet count recovery between the IFN+ and IFN- group. The incidence of acute and chronic GVHD, VOD and severe mucositis was not significantly different. Relapse and both overall survival and DFS were similar for both groups. No adverse effects of prior IFN exposure on the outcome of HLA-identical sibling donor BMT for chronic phase CML patients were found in this study.

Adolescent↗
PubMed1998

A comparative study of mast cells and eosinophil leukocytes in the mammalian testis.

The existence of a physiological integration between the immune and endocrine systems has long been recognized. In spite of the abundant literature data on the presence of cells of the immune system in the testis, mast cells and eosinophil leukocytes have received little attention. We have studied the presence, distribution and numbers of mast cells and eosinophils in the testes of 12 mammalian species. Mast cells were frequently found in equine (stallion, ass and mule) and human testis, whereas eosinophils were nearly absent. On the contrary, eosinophils were abundant in the hare testis, while mast cells were lacking. Both cells types were present in high numbers in swine (wild and domestic boar) testis. Otherwise, mast cells and eosinophils were absent from the testicular parenchyma of several species (rat, dog, cat, bull and deer), although they were present, in most cases, around blood vessels in the tunica albuginea. The presence of high numbers of mast cells and/or eosinophil leukocytes in the testicular parenchyma of some species suggest a role for these cells in local regulatory pathways.

Animals↗
PubMed1998

Effects of N-methyl-D-aspartic acid and kainic acid on prolactin secretion in hyper- and hypoprolactinaemic conditions.

OBJECTIVE: The stimulatory and inhibitory effects of N-methyl-D-aspartic acid (NMDA) and kainic acid on prolactin (PRL) secretion have been correlated with the serum prolactin concentrations before drug administration. In the present experiments, we analysed the role of NMDA and kainic acid in PRL secretion in females with different serum concentrations of PRL. METHODS: Hypoprolactinaemic females were obtained by ovariectomy or after administration of diethyldithiocarbamate (an inhibitor of dopamine-beta-hydroxylase). Chronic hyperprolactinaemia was induced by neonatal administration of testosterone or oestradiol and acute hyperprolactinaemia was induced either by administration of alpha-methyl-p-tyrosine (an inhibitor of tyrosine hydroxylase) or by ether exposure. To analyse the role of dopamine in the effects of NMDA, we measured pituitary concentrations of dopamine after NMDA treatment and the effects of pretreatment with domperidone. RESULTS: (1) NMDA, but not kainic acid, stimulated PRL release in cyclic females. This effect was independent of serum PRL concentrations and was not accompanied by a decrease in pituitary concentrations of dopamine. (2) NMDA did not change PRL secretion in neonatally androgenized females, whereas NMDA and kainic acid inhibited PRL release in neonatally oestrogenized females. The inhibitory effects of NMDA and kainic acid were blocked by domperidone. (3) Kainic acid inhibited PRL secretion in prepubertal hyper- and hypoprolactinaemic rats. (4) Hyperprolactinaemia induced by ether stress was counteracted by administration of NMDA and kainic acid. CONCLUSIONS: (a) NMDA has a dual effect on prolactin secretion that is independent of prior prolactin concentrations and of dopamine activity, but kainic acid is only inhibitory. (b) The stimulatory or inhibitory effects of NMDA and kainic acid on PRL secretion were not strictly related to basal PRL concentrations and necessarily involved a change in the secretion of prolactin releasing factors, as no correlations were observed between changes in pituitary concentrations of dopamine and serum PRL concentrations. (c) Females rendered hyperprolactinaemic by neonatal administration of testosterone or oestradiol responded differently after NMDA administration. (d) NMDA and kainic acid blocked the mechanisms involved in stress-induced PRL secretion.

Animals↗
PubMed1998

Capillary electrophoresis for rapid profiling of organic acidurias.

Organic acids analysis is a powerful technique in the diagnosis of inborn errors of metabolism. Clinically, patients present with severe symptoms, and early detection and appropriate treatment are often lifesaving. Most of the existing methods are based on gas chromatography in combination with mass spectrometry and require sophisticated equipment and complex sample pretreatment and derivatization. We propose a rapid, simple, and automated capillary electrophoretic method for routine analysis of urine to detect 27 organic acids related to metabolic diseases. With this method, direct measurements are performed on samples after initial centrifugation and dilution, if needed. Separation is performed in pH 6.0 phosphate buffer with methanol added as an organic modifier, -10 kV applied potential, and ultraviolet detection at 200 nm. The assay is completed in <15 min, and alternative separation conditions are proposed in case of overlapping peaks. The developed method allows the identification and quantitation of methylmalonic, pyroglutamic, and glutaric acids in samples of patients with diseases related to these acids.

Carboxylic Acids↗
PubMed1997

S6 ribosomal protein phosphorylation and translation of stored mRNA in maize.

This article focuses on the effect that S6 ribosomal protein phosphorylation might have in regulating mRNA translation. Maize axes of either 4 or 14 h of germination were pulse-labelled for 1 h with [32P]-orthophosphate. Analysis of their ribosomal proteins by gel electrophoresis and autoradiography showed distinctive levels of S6 ribosomal protein phosphorylation for both ribosomal sets. Axes at these two stages of germination were treated with alpha-amanitin to ensure transcription inhibition and pulse-labelling with [35S]-methionine. The [35S]-proteins, resulting from stored mRNA translation, when analysed by 2-D-gel electrophoresis and fluorography revealed distinctive [35S]-protein patterns. In vitro translation of stored mRNA on ribosomes from either 4 or 14 h germinated-maize axes produced different [35S]-protein patterns. Further, addition of 7methyl-GTP-Sepharose to the translation system showed differential cap-dependent protein synthesis inhibition depending on the set of ribosomes tested. It is concluded that translation of stored mRNA in germinating maize axes is at least partially regulated by a mechanism that involves S6 ribosomal protein phosphorylation.

Amanitins↗