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Biomedical subjects

R Fernandez

Publications and source records attributed to R Fernandez.

At least 127 records · Page 7Linked to original sources
PubMed1987

Surgical treatment of the static perineal modifications in spinal cord or cauda equina lesions.

Severe dysuria, due to insufficiency of the perineal floor associated during micturition with a posterior tilting of the prostate-bladder block in lower or in associated upper and lower motor neuron lesions, can be treated surgically by a prostato cytso pexy. Since 1971, eight patients with post-traumatic conus and/or cauda equina lesions have been treated by this intervention. On the follow-up the satisfactory results appear to remain stable. An alternative surgical technique using the abdominal pyramidalis muscle is described so as to fix the prostate, associated with a bladder-pexy. The recurrence of dysuria, after the intervention, has always been caused by an additional lower urinary tract pathology. The comfort of the patients has been greatly improved.

Abdominal Muscles↗
PubMed1987

[Invasive cancer of the prostate. Reconstruction of the lower urinary tract by prostatic resection and ureteral reimplantation into the bladder vault].

Some prostatic cancers (T4) spread out along the ureters to the kidneys. Patients, usually arrive with terminal renal failure and bladder retention and have often fast-advancing cancer with massive nodes invading. T.U.R., reimplantation of the ureters into the bladder dome or into a psoïc bladder and the specific treatment of the cancer, have often permitted these patients to survive for some years without any dialysis. In these cases we often find very important lower limbs oedema. With lymphatic nodes radiotherapy and subcutaneous injections of heparin, these oedema may regress completely.

Aged↗
PubMed1986

Hexokinase PII from Saccharomyces cerevisiae is regulated by changes in the cytosolic Mg2+-free ATP concentration.

Hexokinase PII is not inhibited by high Mg-ATP concentrations if the Mg2+-free ATP is kept at low levels (0.01 mM) in the assay mixture. Hexokinase PI activity is not affected either by Mg2+-free ATP nor by free Mg2+ in the assay mixture. Thus, hexokinase PI and PII activities appear not to be regulated by substrate inhibition as proposed previously [Kopetzki, E. & Entian, K. D. (1985) Eur. J. Biochem. 146, 657-662]. However, the level of Mg2+-free ATP in the hexokinase PII assay mixture strongly affects the enzyme activity by decreasing the Vmax and increasing the Km value for Mg-ATP from 0.15 mM to 5.0 mM. The physiological role of this inhibition, which has not been described previously, was investigated by determining the cytosolic ATP and Mg2+ concentrations in yeast cells grown under derepressing and repressing conditions. Derepression is accompanied by an important loss of Mg2+ from the cells, maintaining the ATP concentration constant. This produces an increase of Mg2+-free ATP in the cytosol from 0.01 mM to 0.1 mM. This free ATP concentration would lead to a maximal inhibition of hexokinase PII.

Adenosine Triphosphate↗
PubMed1986

Evidence for an HLA-DR4-associated immune-response gene for Mycobacterium tuberculosis. A clue to the pathogenesis of rheumatoid arthritis?

Antigens of Mycobacterium tuberculosis, M leprae, M scrofulaceum, and M vaccae were injected intradermally in 86 caucasoid leprosy patients, and skin responses (measured in mm of induration at 72 h) were analysed in relation to HLA class II phenotypes. HLA-DR4 was associated with high responsiveness to antigens specific to M tuberculosis but not to antigens shared with other mycobacteria (p = 0.0005). Because DR4 is associated with rheumatoid arthritis (RA) and because a role for M tuberculosis antigens has been suggested both in experimentally induced autoimmune arthritis in rats and in RA, the DR4 associated regulation of the immune response to M tuberculosis may be relevant to the pathogenesis of RA.

Arthritis, Rheumatoid↗
PubMed1986

Isolation of a Drosophila genomic sequence homologous to the kinase domain of the human insulin receptor and detection of the phosphorylated Drosophila receptor with an anti-peptide antibody.

A Drosophila genomic fragment has been isolated with a deduced amino acid sequence that is strikingly homologous to that of the kinase domain of the human insulin receptor. The Drosophila DNA hybridizes with an 11-kilobase mRNA that is most prominent in 8- to 12-hr embryos. An anti-peptide antibody prepared to a sequence in the human insulin receptor kinase domain that is conserved in the Drosophila sequence immunoprecipitates a single 95-kDa Drosophila protein whose phosphorylation on tyrosine residues is dependent on insulin. We conclude that the DNA sequence is that of the kinase domain of the Drosophila insulin receptor and that the 95-kDa phosphoprotein is the autophosphorylated beta subunit of that receptor. The results are compatible with our previous reports demonstrating a specific insulin-binding Drosophila glycoprotein and an insulin-dependent tyrosine protein kinase whose activity is greatest during embryogenesis. The observations suggest a role for insulin-dependent protein tyrosine phosphorylation during embryogenesis.

Amino Acid Sequence↗
PubMed1986

Laminated cytoplasmic bodies in Schwann cells and phagocytes: an ultrastructural and cytochemical study in the normal and lead-damaged peripheral nervous system of the rat.

We studied the distribution and cytochemical characteristics of laminated bodies (LBs) in the peripheral nervous system of normal and lead-intoxicated rats. In normal rats, LBs were exclusively present in myelin-forming Schwann cells (SCs). Nerves from lead-intoxicated animals showed extensive demyelination and remyelination. In these nerves we found an increase of LBs in the SC cytoplasm, and also within phagocytes involved in myelin removal, but not in remyelinating SCs. Cytochemical studies revealed that LBs were positive for acid phosphatase, thus demonstrating the lysosomal nature of such inclusions. Taken together, these data suggest that LBs are autophagolysosomes derived from myelin catabolism, which may be enhanced in the lead-induced demyelinating neuropathy of the rat. The possible mechanisms underlying this phenomenon and their pathological relevance are discussed.

Acid Phosphatase↗
PubMed1985

Demyelination-induced plasticity in the axon membrane: an ultrastructural cytochemical study of lead neuropathy in the rat.

We examined the distribution of ferric ion-ferrocyanide stain (a marker for excitable regions of myelinated fibers) in the lead-induced demyelinating neuropathy of the rat. By electron microscopy, we found that paranodal degeneration resulted in spreading of the reaction product from nodal to internodal axolemma. During repair, nodal-like stained areas formed at the contact zones between preremyelinating Schwann cells. These data suggest that the location and extent of excitable axonal regions are influenced by axoglial relationships. Additionally, some fibers displayed staining at paranodal axolemma adjacent to demyelinated segments, suggesting it might be an alternative site for impulse generation in demyelinated fibers.

Animals↗
PubMed1985

Antibodies to peptides corresponding to a conserved sequence of gonococcal pilins block bacterial adhesion.

Antisera generated against each of seven synthetic peptides corresponding to constant and variable sequences of the pilin from gonococcal strain MS11 were assayed for their ability to crossreact with intact pili from both homologous and heterologous strains. The peptides elicited roughly equal antipeptide responses but varied substantially in their ability to elicit antisera that crossreacted with intact pili. Of the antisera to peptides corresponding to regions of conserved sequence, antisera directed against residues 69-84 were the most efficient in binding pili from all strains tested in both solid-phase assays and immunoblots. Anti-69-84 also efficiently precipitated a tryptic fragment of pilin known to bind human endocervical cells. Sera against the two peptides (121-134 and 135-151) previously shown to contain strain-specific epitopes crossreacted with MS11 pili equally well, but differed in their ability to bind pili from heterologous strains. Anti-121-134 was strain-specific whereas anti-135-151 bound all pilin tested. Each of the sera was examined for its ability to inhibit bacterial adhesion to a human endometrial carcinoma cell line. Sera generated against residues 41-50 and 69-84 successfully inhibited a heterologous gonococcal strain from binding. These peptides could be important components of an effective vaccine for the prevention of gonorrhea.

Adhesiveness↗
PubMed1984

Strain-specific and common epitopes of gonococcal pili.

The antigenic structure of gonococcal pilin, strain MS11 (Tr), was investigated by assaying the binding of antisera engendered by intact pili from strains MS11 and R10 and their two major cyanogen bromide-generated fragments, CNBr-2 (residues 9-92) and CNBr-2 (residues 93-159), to synthetic peptides corresponding to the amino acid sequence of MS11 pilin. Four peptides were synthesized corresponding to regions of sequence variation between MS11 and R10 gonococcal pilin. Antisera against the homologous pilus filament and against its CNBr-3 fragment bind peptides equivalent to residues 121-134 and 135-151, which comprise the 30 amino acid disulfide loop near the carboxyl terminus of the protein. Heterologous pili antisera did not bind these peptides. Absorption studies proved that each peptide contained an independent, strain-specific epitope. Synthetic peptides corresponding to regions of identical sequence between MS11 and R10 pilin were used in similar binding experiments to localize a weakly immunogenic, common determinant between residues 48 and 60. less than 15% of the antibodies raised against intact pili were directed at this site. Antisera raised against MS11 or R10 CNBr-2 bind a separate peptide, residues 69-80. This region is immunogenic only as a fragment, not in the intact pilus filament.

Amino Acid Sequence↗
PubMed1984

Gonococcal pili. Primary structure and receptor binding domain.

The complete amino acid sequence of pilin from gonococcal strain MS11 and the sequence of constant and variable regions from strain R10 pilin have been determined in order to elucidate the structural basis for adherence function, antigenic diversity, and polymeric structure. The MS11 pilin sequence consists of 159 amino acids in a single polypeptide chain with two cysteines in disulfide linkage and serine-bonded phosphate residues. TC-2 (31-111), a soluble monomeric pilus peptide prepared by arginine-specific digestion, bound human endocervical, but not buccal or HeLa cells and therefore is postulated to encompass the receptor binding domain. Variable regions of CNBr-3 appear to confer antigenic diversity and comprise segments in which changes in the position of charged residues occur in hydrophilic, beta-turns. Residues 2-21 and 202-221 of gonococcal pilins and lower eucaryotic actins, respectively, exhibit 50% homology. When these residues are arranged at intervals of 100 degrees of arc on "helical wheels," the identical amino acids comprise a hydrophobic face on one side of the helix. This observation, the hydrophobic character of this region and the tendency for TC-1 (residues 1-30) to aggregate in water, suggest that this stretch interacts with other subunits to stabilize polymeric structure.

Amino Acid Sequence↗