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P Quesada

Publications and source records attributed to P Quesada.

At least 55 records · Page 3Linked to original sources
PubMed1994

Histone-induced condensation of rat testis chromatin: testis-specific H1t versus somatic H1 variants.

Due the likely role of H1 histone variants in inducing the formation of folded DNA filaments with different stabilities, the condensing capacity of the testis-specific H1t versus the somatic variants was tested. Circular dichroism analyses of rat testis H1-depleted oligonucleosomes (5-2kbp) revealed that H1t, which appears in germ cells during the meiotic prophase of mammalian spermatogenesis, exerts the lowest condensing effect as compared to the other variants. The distribution of H1 subtypes among different chromatin fractions was also investigated and gave evidence that H1t is more abundant in chromatin regions which are more sensitive to DNAase I digestion.

Animals↗
PubMed1994

Nuclear matrix-associated poly(ADPribosyl)ation system in rat testis chromatin.

The presence of poly(ADPR)polymerase in the third level of rat testis chromatin, i.e., in stripped chromatin loops and nuclear matrix, was assessed using enzymatic assays, activity blots, and Western blots. The distribution and the size of ADPribose polymers associated to proteins of the same nuclear fractions was analyzed after incubation of intact isolated nuclei with [14C]- or [32P]NAD+. Short ADPribose oligomers, not larger than 3 residues, were found to be associated to tightly bound chromosomal proteins, which resisted extraction by 2 M NaCl, whereas longer oligomers (8-13 residues long) were associated to loosely bound chromosomal proteins. The identity of ADPribose-protein conjugates was determined by autoradiographic analysis of nuclear protein extracts. Tightly bound histone-like proteins appear to be ADPribosylated both in stripped chromatin loops and in nuclear matrix.

Animals↗
PubMed1993

[Effectiveness of the partial velopalatine++ resection in obstructive apnea syndrome during sleep. Experience with 57 patients].

BACKGROUND: The aim of this study was to determine the result of partial resection of the soft palate (SPR) as a treatment of the obstructive apnea syndrome during sleep (OASS). METHODS: Fifty-seven patients diagnosed of OASS treated with SPR were studied. The clinical and polysomnographic results prior to surgery and after 6 months were compared. RESULTS: Prior to SPR the 57 patients had a mean index of apnea plus hypopnea per hour of 57 (IAH) and following surgery the same was of 19.2 (p < 0.0001). IAH improved more than 50% in 42 patients (74%), 30 of whom were cured (IAH < or = 10). Daily hypersomnia and snoring disappeared in 58% of the patients and decreased in intensity in most of the remaining cases. The secondary effects observed following SPR were: rhinolalia, nasal fluid reflux, and oropharyngeal disturbances, being present in 32 patients (56%) and permanent, although slight, in only 13 (23%). CONCLUSIONS: Soft palate resection is a good surgical procedure for therapy of obstructive apnea during sleep, with only slight secondary effects.

Adult↗
PubMed1993

Effect of ADP-ribosylation reaction on bull testis chromatin.

Polynucleosomes prepared from bull testis nuclei were characterized: DNA length, by agarose gel electrophoresis, and distribution of poly(ADP-ribose)polymerase activity, by incubation with 0.64mM NAD were determined. Maximal activity was found in nucleosome fractions of 3-5 units. Chromatin fragments (5-2 kbp polynucleosomes) were analysed by circular dichroism in both native and ADP-ribosylated forms. The spectrum of the endogenously ADP-ribosylated polynucleosomes, compared to the native fraction, exhibited a higher ellipticity value and a shift of the cross-over point towards the lowest wavelengths, behaving like an H1-depleted chromatin.

Adenosine Diphosphate Ribose↗
PubMed1991

In vitro poly(ADPribosylation) of estrogen-induced proteins from the oviduct of the lizard Podarcis s. sicula Raf.

Poly(ADPribosylation) of nuclear proteins has been investigated in the nuclei from growing oviducts of intact and estrogen-treated spayed females of the lizard Podarcis s. sicula Raf. Isolated nuclei were incubated with [14C] NAD and nuclear proteins extracted in 0.2 m H2SO4. Labeled acid-soluble proteins were analysed by reverse-phase high-performance liquid chromatography (HPLC) and acetic acid-urea gel electrophoresis. The results reported here indicate that the ADPribosylation reaction is involved in modifying besides histone H2b, tissue specific proteins (SNPs and LMG-O). Moreover, comparable results have been obtained from nuclei prepared from the fully active oviduct of intact animals and spayed lizards stimulated with 17 beta-estradiol. It is concluded that the poly-(ADPribosylation) of hormone-induced proteins might play a role in the differentiation of the lizard oviduct.

Amino Acids↗
PubMed1991

Cell cycle perturbating agents in a line of human thyroid transformed cells in culture (HuT).

Culture and differentiation parameters of a human thyroid transformed cell line (HuT) were analyzed. Treatment with high concentrations of chemical agents namely dimethyl sulphoxide and retinoic acid, exerted a dramatic cytotoxic effect. The exposure of these cells to the lowest doses of retinoic acid as well as to 8 mM-16 mM 3-aminobenzamide a potent inhibitor of poly(ADPribose)polymerase, resulted in a delay of cell proliferation. Poly(ADPribose)polymerase activity was differently affected by retinoic acid (stimulation) and 3-aminobenzamide (inhibition).

Benzamides↗
PubMed1991

Extramedullary nasal plasmacytoma.

The literature on this rare tumour has been reviewed and three cases of nasal plasmacytoma are described. Immunohistochemistry demonstrated cytoplasmic IgA and Kappa determinants in all cases. Two patients are disease-free at the present time, the third developed an IgG-k multiple myeloma, previously not described in the literature.

Aged↗
PubMed1991

Acute epiglottitis in the adult.

Acute epiglottitis in the adult is a rare disease, which has shown an appreciable increase since the sixties and in our locality since 1984. We present a review of the cases registered in our hospital, analyzing their aetiology, evolution and treatment. The disease is most likely to be suspected in the presence of any patient having a sudden dysphagia, especially if he shows symptoms of an acute infection and a lack of oropharyngeal pathology.

Acute Disease↗
PubMed1991

Reciprocal inhibition between forearm muscles in spastic hemiplegia.

We studied reciprocal inhibition of H-reflexes in the forearm flexor and extensor muscles in 14 patients with spastic hemiplegia secondary to a focal cerebral lesion and 14 normal volunteers. In the spastic limb, the Hmax/Mmax ratio was increased in both flexor and particularly extensor wrist muscles. The 3 normal inhibitory phases of reciprocal inhibition between extensor and flexor forearm muscles were markedly reduced on the spastic side of patients. The early disynaptic phase showed the greatest alteration. Reduced or absent inhibition between forearm muscles associated with increased spinal motoneuron excitability may be typical to spastic hemiplegia.

Brain Diseases↗
PubMed1991

Analysis of a below-knee patellar tendon-bearing prosthesis: a finite element study.

In this study, a finite element (FE) model of a below-knee prosthesis of patellar tendon-bearing (PTB) design, and several altered variations of the model have been constructed. A load of approximately 1.5 times normal body weight (984 N) was applied at the heel of the model to simulate heelstrike conditions. The "base" model was then analyzed and revised iteratively until a model which provided consistency between soft tissue elastic modulus and socket displacement was developed. The interface normal and shear stresses obtained from the analysis of this revised base model were highest (about 961, and 463 KPa, respectively) at the distal anterior tip of the socket/stump. Proximally, higher normal stresses (72-78 KPa) were found medially and posteriorly. Proximal shear stresses were highest posteriorly (79 KPa), although shear stresses medially (51 KPa), and laterally (43 KPa), were also much higher than anteriorly (10 KPa). FE analyses were performed on the altered models to determine the relative effects on socket/stump interface stresses of altering the FE model of the prosthesis. Results of the analysis indicate that fabricating the prosthesis from a material with an elastic modulus ten times lower than that of the revised base model can produce reductions in the maximum pressure of up to 14 percent. Large decreases in maximum pressures (71 percent) resulted from the use of a suction socket rather than a conventional socket. Small changes in stump length (2 cm) caused relatively large pressure changes (16 to 18 percent).

Amputation, Surgical↗
PubMed1991

[The electronystagmographic protocol for tracking vestibular dysfunction].

This prospective protocol for vestibular exploration offers the results gained through 296 patients complaining from vestibular disorders. The aim of the AA. is to check the validity of the test proposed (in the midst of the battery of electronystagmographic explorations), consisting in the thermal bilateral and simultaneous stimulation of the labyrinths. They consider this trial very useful because of its sensibility, quickness and tolerance.

Electronystagmography↗
PubMed1990

ADP-ribosylation of nuclear proteins in rat ventral prostate during ageing.

Poly(ADPR)polymerase activity and poly(ADP-ribosyl)ation of nuclear proteins have been investigated in ventral prostate nuclei of different aged rats (14, 28, 60, 180, 360 day old animals), by reverse-phase HPLC and acetic acid-urea polyacrylamide gel electrophoresis. The major ADP-ribose acceptor proteins were identified as histone H1 and H2b. It is concluded that concomitant with major changes to chromatin organization, poly(ADP-ribosyl)ation reaction is progressively inhibited during aging of rat ventral prostate. These results support the hypothesis that prostatic dysfunction in senescent animals is related to a failure of DNA repair mechanisms and deregulated template activity.

Aging↗
PubMed1990

In vitro inhibition of HeLa cell nuclear ribonucleases by ADP-ribosylation.

Ribonuclease activity in HeLa cell nuclei is markedly inhibited by ADP-ribosylation following incubation of intact isolated nuclei with [14C]NAD. Time course experiments demonstrate that [14C] incorporation into proteins is accompanied by a 50% inhibition of ribonuclease activity on single-strand and double-strand polynucleotides. Inhibition does not occur when 3-aminobenzamide, a potent (ADP-ribose) polymerase inhibitor, is present. Two enzymatic activities that degrade double-strand polynucleotides have been purified and partially characterized. A relevant level of radioactivity resulting from [14C]NAD incubation of nuclei was associated to the purified enzyme. The RNase F1 component, which shows maximal activity on polyU-polyA is demonstrated to be the major ADP-ribose acceptor protein.

Cell Nucleus↗