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Biomedical subjects

A Solari

Publications and source records attributed to A Solari.

At least 91 records · Page 5Linked to original sources
PubMed1986

A morphometric study of mouse trigeminal roots after unilateral destruction of vibrissae follicles at birth.

Trigeminal sensory roots were studied in neonatal mice. On the deafferented side, the surface area of the cross-section through the sensory root is diminished by 31% and the number of myelinated fibers is reduced by 21%, but the proportion between myelinated and unmyelinated fibers remains unchanged. The distribution of axonal diameters, analysed in 7 dorso-ventral scanning bands through the sensory roots, indicates a loss or eventually an atrophy of large myelinated axons in the medial two thirds of the sensory root. In both control and deafferented sides the diameter of the myelinated fiber (outside the myelin sheath) is proportional to the axon diameter (inside the myelin sheath). Our results confirm the loss of most of the neurons innervating vibrissae and the lack of regeneration or sprouting in the deafferented root in the newborn mouse.

Animals↗
PubMed1986

Studies on DNA polymerases of Xenopus laevis oocytes: subcellular distribution and physical association of DNA polymerase alpha inside the nucleus.

The localization of DNA polymerases in Xenopus laevis oocytes and eggs was studied. Oocytes have a high level of DNA polymerase alpha activity detected exclusively in the nuclei, while mitochondria contain all the DNA polymerase activity of the gamma type. No DNA polymerase beta activity is present in the nuclear fraction. Moreover, the beta activity is not present in unfertilized eggs. In oocytes, DNA polymerase alpha is weakly bound to the nucleoplasm. The leakage of the enzyme from whole nuclei can be prevented using polyvinylpyrrolidone, a nuclear pore sealing agent.

Animals↗
PubMed1985

Influence of testosterone on precocious sexual development in immature rainbow trout.

The influence of testosterone on plasma and pituitary levels of gonadotrophin (GTH) as well as on gonadal development was studied in immature rainbow trout. Among the animals receiving a testosterone-cocoa butter implant (200 micrograms) at the age of 5 months, gonadal puberty occurred 8 months later in half of the males (opposite to the controls which remained immature) and the beginning of oocyte maturation was observed in only one female. These animals were characterized by a higher pituitary GTH level. Owing to the multivariate statistical analyses made, it was possible to provide evidence for the presence of two populations with different reactions to the same steroid treatment. They also confirmed the existence of a positive testosterone feedback, in the male, leading to a precocious gonadal development. The pituitary GTH load obtained with 200 micrograms of testosterone seemed to be related to the age of first maturation. The secretion of an appropriate level of GTH resulting in the stimulation of gametogenesis required the availability of a relatively large pituitary GTH level and seemed to be possible because the animals were already in the pubertal period. The fact that the highest pituitary GTH level of the treated lot was found in the only female showing a beginning of sexual maturation suggests that testosterone may also act in females.

Animals↗
PubMed1985

Classic migraine--clinical findings in 164 patients.

Clinically the presence or absence of prodromes has always been regarded as the only distinctive feature differentiating classic migraine from common migraine. As a preliminary step for identifying any other distinctive clinical features peculiar to these two conditions, we thought it useful to review the clinical picture of classic migraine by investigating 164 patients (113 females and 51 males) aged 7-75 years. The prodromal phase consisted of scintillating scotomas (with hemianopic distribution in over half of the cases) in 79.3%, of paraesthesias mostly with cheiro-oral distribution in 29.9%, and of aphasic disturbances in 17.1%. When several neurological symptoms were present in the prodromal phase, their occurrence followed a regular sequence in time. The prodromes lasted less than 30 min in 75.6% of the cases. Only in about half the patients was pain contralateral to the peripheral location of the prodrome. The headache was generally not severe and short lived.

Adolescent↗
PubMed1985

[Influence of the photoperiod on the production and fecundity of spermatozoa in the adult Ile-de-France ram].

Two groups, A and B, of 5 adult Ile-de-France rams each of the same age were exposed for 52 weeks (October 1975 to October 1976) to an artificial light regime reproducing natural variations of daylength (DL). In group A, DL increased from 8 to 16 h during the first 26 weeks and then decreased. In group B, DL varied in an opposite manner. Light intensity was constant (300 lux/m2) and ambient temperature was controlled (20 +/- 4 degrees C). The rams were collected using an artificial vagina twice weekly (2 X 2 ejaculates/male/week) during the whole experimental period (EP). The volume and concentration of each ejaculate were recorded. The pH of the raw semen was also measured on the first ejaculate once a week or every two weeks, according to material possibilities. The unselected ejaculates of all rams were used for artificial insemination (AI) on the same days in the same flocks between January and October 1976. AI (980 ewes) was always carried out after oestrus synchronization (FGA + PMSG). Amongst these ejaculates, some (3 ejaculates/male/group/period) could be used for both in vitro (pH) and in vivo (AI) measurements: - Weekly sperm production (SP) varied in an opposite manner in both groups during the whole EP. In group A, minimal (10.6 +/- 4.0.10(9) and maximal (25.5 +/- 5.1.10(9] levels were reached from weeks 12 to 28 and weeks 38 to 52, respectively. In group B, SP was maximal (21.8 +/- 2.3.10(9] from weeks 9 to 24 and minimal (12.7 +/- 5.2.10(9] from weeks 36 to 49. The differences between rams were significant within periods of high and low production. - The sperm pH was somewhat higher in both groups when DL increased and vice-versa. Fertility after AI was higher with rams exposed to short days than with rams exposed to long days (65.7 vs 56.7%; P less than 0.01). The season of AI had no effect on mean fertility (61.0 vs 62.3% for ewes inseminated from January to June and from July to October, respectively), whatever the DL. No correlation was found between the pH of the sperm and its fertilizing ability. From January to April, a highly significant correlation existed between fertility and prolificacy in the 10 rams (r = + 0.607). These results show that photoperiodism has an important effect on both ejaculated sperm production and fertility in rams.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Stimulation of DNA synthesis by microinjection of diadenosine 5',5''-P1, P4-tetraphosphate (Ap4A) into Xenopus laevis oocytes.

Ap4A stimulated DNA synthesis when injected into oocytes. The stimulation was dramatically increased when an exogenous template was microinjected. Aphidicolin inhibited the effect of Ap4A, supporting a role of DNA polymerase alpha in this process. No stimulation by Ap4A was observed in microinjected eggs, nor ATP was able to mimic the in vivo effect of Ap4A. Besides microinjected activated DNA, the stimulation by Ap4A of DNA synthesis was also observed with poly dT and poly dT-poly dA as templates, while no effect was observed with poly dA- dT12 -18 and poly dC- dG12 -18. These results support a role of Ap4A in the initiation of DNA synthesis.

Adenine Nucleotides↗
PubMed1984

Changes in steroid concentrations in follicular fluid and sexual behavior during pseudopregnancy in the rabbit.

Changes in sexual behavior and progesterone, oestrone, oestradiol, testosterone and androstenedione concentrations have been studied in the follicular fluid of 25 pseudopregnant rabbits on Days 6, 9, 12, 15 and 18. The sexual behavior score seemed to rise at the end of pseudopregnancy and follicular steroid levels were higher on Days 6 and 18 of pseudopregnancy than on Days 9, 12 or 15. The generalized distance D2 of Mahalanobis showed the existence of four periods during pseudopregnancy: Day 6, Days 9 and 12 which were similar, Day 15 and Day 18. These stages were found to differ by a compound of the sexual behavior score and the concentrations of androgens and oestradiol in follicular fluid. There was no relationship between sexual behavior and follicular steroid concentrations. Nevertheless, undetectable levels of oestradiol in the follicular fluid were only observed in deeply dioestrus females.

Androstenedione↗
PubMed1984

Exonucleases participating in the 3'end turnover of tRNA in Xenopus laevis.

Nuclei and enucleated Xenopus laevis oocytes were used as a source of exonucleases that hydrolyze the 3'terminus sequence of tRNA. The majority of the total activity was found in the cytoplasm. Several forms of enzyme activity are obtained upon fractionation in S-200 column. Both nuclear and cytoplasmic activities display a preferential cleavage of the terminal AMP residue. Similar results are obtained in vivo by microinjection of tRNA labelled in the CCA sequence. Aminoacylation of tRNA, on the other hand, protects the terminal nucleotide against exonuclease activity.

Animals↗
PubMed1983

Identification of multiple RNases in Xenopus laevis oocytes and their possible role in tRNA processing.

A survey of RNases in Xenopus laevis oocytes has been carried out to identify potential tRNA-processing enzymes in this system. Using a variety of specific and nonspecific substrates, we have shown that oocytes contain multiple RNases with various specificities. Three activities that could cleave the extraneous residues from the artificial tRNA precursor, tRNA-C-[14C]U-C, to generate a substrate for -C-C-A addition by tRNA nucleotidyltransferase were identified. One of these was a cytoplasmic exonuclease which generated predominantly tRNA-C, whereas the other two were nuclear endonucleases which cleaved the precursor to generate tRNA-N. The possible involvement of these activities in 3' tRNA processing in oocytes is discussed.

Animals↗
PubMed1983

In vitro and in vivo studies of Trypanosoma cruzi DNA polymerase.

One major DNA polymerase has been purified and characterized from Trypanosoma cruzi. The enzyme has a sedimentation coefficient of 6.8 S corresponding to an approximate molecular weight of 180,000 assuming a globular shape. The enzyme recognizes activated DNA very efficiently, as well as synthetic polydeoxynucleotides, whereas poly rA-dT12 is very poorly utilized. Trypanosoma cruzi DNA polymerase is not inhibited at all by aphidicolin, while araCTP inhibits the enzyme very slightly. The purified enzyme is strongly inhibited by N-ethyl maleimide, dideoxyTTP, ethidium bromide and berenil. All our attempts to find a DNA polymerase sensitive to aphidicolin in vitro have failed, nor have we been able to find a low molecular weight DNA polymerase in this organism. However, when DNA synthesis was studied in whole trypanosomes, aphidicolin was shown to inhibit DNA synthesis more efficiently than ethidium bromide and berenil.

Animals↗
PubMed1983

[Use of reference plasmas for estimating the accuracy of radioimmunological titration measurements].

This article presents a method for estimating the variability of measurements in radio-immunoassays. Repeated assays are carried out on the same plasma used as a reference. The variances of repeatability (or intraassay) and reproducibility are calculated from the values obtained from the reference. These variances are used to calculate the agreement between two or more values obtained from unknown plasma. Analysis of the values of the plasma reference completes information obtained from standard curves.

Analysis of Variance↗
PubMed1982

Subcellular localization of the tRNA processing enzyme, tRNA nucleotidyltransferase, in Xenopus laevis oocytes and in somatic cells.

Earlier studies of the tRNA processing enzyme, tRNA nucleotidyltransferase, in rat liver cells suggested that the enzyme was absent from nuclei, whereas more recent studies with tRNA transcription-processing systems from Xenopus laevis oocytes indicated that the enzyme was present in germinal vesicles of these cells. In order to resolve this apparent discrepancy, the subcellular localization of tRNA nucleotidyltransferase in oocytes was directly determined, and its distribution in somatic cells was re-examined. Oocyte germinal vesicles, isolated manually, contained about 25% of the total tRNA nucleotidyltransferase activity of the cell, but the enzyme rapidly leaked out of these nuclei during storage. In contrast, purified nuclei isolated from rat or Xenopus liver using a variety of aqueous procedures were devoid of tRNA nucleotidyltransferase activity. Since rapidly-isolated, crude nuclear preparations from liver contained substantially more of the enzyme than could be accounted for by cytoplasmic contamination, it appears that the enzyme leaks out of the somatic cell nuclei during the lengthy times required for their purification. The implications of these results for the development of tRNA processing systems from somatic cell nuclei are discussed.

Animals↗
PubMed1981

[Carotidynia].

The clinical definition of carotidynia is not a controversial one, whereas how its etiology should be interpreted is still uncertain. The study of the clinical features and the therapeutical results in 12 patients suffering from carotidynia reveals a marked resemblance to migraine. In particular, the case history reported points out a significant incidence of migraine as a familial disease, its special localization and the type of pain, the possible presence of a prodromal stage and the favourable response to the drugs that are known to be effective in migraine treatment. The theory that carotidynia should be ascribed to the group of vascular headaches is therefore suggested.

Adult↗
PubMed1981

Hepatic cholesterogenesis in Chileans with cholesterol gallstone disease. Evidence for sex differences in the regulation of hepatic cholesterol metabolism.

To test the hypothesis that hepatic cholesterol synthesis and concentration are specifically increased in women and men with cholesterol gallstone disease, we studied in a series of 24 surgical liver biopsy specimens, the rate of acetate incorporation into cholesterol and CO2, and the concentration of free and esterified cholesterol. There were 6 women in each group of 12 control and 12 gallstone patients. Therefore, hypersecretion of biliary cholesterol, a common finding in Chileans with gallstones, is not pathologically linked to a basic biochemical abnormality in the hepatic cholesterogenic pathway. The concentrations of hepatic cholesterol were similar in patients with and without gallstones. However, there were significant increments of 37% in the free fraction and 78% in the esterified fraction of hepatic cholesterol in female subjects, irrespectively of the presence of cholelithiasis. These results suggest that the flux of lipoprotein cholesterol to the liver is increased in women. The regulatory mechanism of hepatic cholesterogenesis is less sensitive to cellular cholesterol in women than in men, as the fluxes of acetate into cholesterol are similar to both sexes, in spite of the significant increase of hepatic cholesterol in females. These findings demonstrate that sex factors play a fundamental role in the regulation of cholesterol metabolism in the human liver.

Adult↗
PubMed1980

Differential effect of spermine on nuclear and cytoplasmic transfer RNA methyl transferases from Xenopus laevis Oocytes.

X laevis ovarian tissue or isolated oocytes contain two major tRNA methyl transferase activities capable of methylating total E. coli tRNA using S-adenosyl methionine as a methyl donor. These enzymes can be resolved by chromatography on DEAE-cellulose or by gel filtration on Sephadex G-200 into fractions I and II. The tRNA methyl transferase I which is present mainly in the oocyte nuclei, has a molecular weight of 190,000 and an apparent Km for S-adenosyl methionine of 1.5 microM. The activity of peak II which exists predominantly in the oocyte cytoplasm, has a molecular weight of 125,000 and an apparent Km for S-adenosyl methionine of 17 microM. The most striking difference between these two enzymes, however, resides in their response to spermine or magnesium ions. The nuclear enzyme is activated more that 8 fold by spermine and 4 fold by Mg2+ while the cytoplsmic activity is slightly inhibited by the polyamine and unaffected by Mg2+. The effect of spermine on the nuclear tRNA methyl transferase is highly dependent on the salt concentration since the stimulatory effect of the polyamine decrease at KCI concentrations above 100 mM becoming inhibitory above 200 mM. Spermine increases 4 fold the Vmax of the reaction catalyzed by the nuclear enzyme but does not affect its apparent Km for tRNA which is approximately 2.9 microM. The apparent Km for tRNA of the cytoplasmic enzyme is 3.3 microM.

Animals↗
PubMed1979

Studies on aminoacyl tRNA synthetases and transfer RNA in living Xenopus laevis oocytes.

The microinjection of transfer RNA into amphibian oocytes permits one to study under in vivo conditions the reactions that affect this important macromolecule. A comparative study has been carried out between the in vivo and in vitro specificity of the aminoacylation reacton. The results obtained show that modifications of the tRNA structure affect aminoacyl-tRNA synthetase recognition in the same fashion in both conditions. The in vivo aminoacylation was not affected by the presence of puromycin (0.5mM) or cycloheximide (0.1 mM) which completely inhibited oocyte protein synthesis. An interesting difference was obtained between the in vivo and in vitro aminoacylation of tRNA with regards to temperature requirements. While the in vivo reaction was optimal at 25 degrees and was totally inhibited at 37 degrees, the in vitro was optimal, at the latter temperature. The inhibition of the in vivo reaction at 37 degrees was not due to inactivation of the enzyme. The transfer of the amino acid moiety to nascent proteins was studied by measuring the transfer of radioactivity from injected (14C) phenylalanyl-tRNA into hot trichloroacetic acid precipitable material. It was found that 30% or more of the amino acid became incorporated into oocyte proteins and that this incorporation was due to direct transfer from the aminoacyl-tRNA and was inhibited by puromycin and cycloheximide.

Amino Acyl-tRNA Synthetases↗