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Biomedical subjects

C Gutierrez

Publications and source records attributed to C Gutierrez.

At least 145 records · Page 8Linked to original sources
PubMed1992

Cholesterol emboli neuropathy.

We report the clinical and pathologic features of a patient with peripheral neuropathy that was the first clinical expression of cholesterol emboli syndrome (CES). Biopsy of skeletal muscle and peripheral nerve revealed cholesterol clefts in lumens of small arteries, necrotizing arteritis, and severe degeneration of peripheral and intramuscular nerves. At autopsy, the peripheral nervous system was extensively affected by similar changes. We conclude that (1) peripheral neuropathy may be the initial manifestation of CES. Presumably, deposition of cholesterol leads to arteritis. (2) The underlying pathology of CES neuropathy is chronic axonal degeneration, possibly due to chronic ischemia of epineurial arteries. (3) Muscle biopsy is important in the antemortem diagnosis of CES. Nerve biopsy may show involvement of epineurial vessels. (4) CES may resemble polyarteritis nodosa clinically and pathologically. (5) CES may be under-recognized and should be included in the differential diagnosis of any neuropathy of uncertain cause, particularly when there is a history of vascular catheterization, or severe aortic atherosclerosis.

Aged↗
PubMed1992

Anatomically complete heterograft mitral valve substitute: surgical technique and immediate results.

The use of a totally anatomical mitral valve heterograft as a mitral valve substitute has been proven to be technically feasible. A new stentless mitral porcine heart valve substitute was therefore developed to match the physiology and flow characteristics of the left ventricle and mitral valve complex, and tested in non-survival animal experiments. Having sought the approval of the Hospital Ethics Committee and the consent of each individual patient, this valve was implanted into 18 patients with diseased mitral valves. The duration of the procedure is approximately the same as for standard mitral valve replacement. The sizing of the valve and the anchoring of the sutures to the papillary muscle, although very straightforward, do require adherence to a protocol. The immediate clinical results are encouraging, although the first patient required a reoperation because of a patient/valve mismatch. All patients, including the patient reoperated, are in functional class I after four to 26 weeks of follow up. The patients will be followed by monthly clinical and Doppler echocardiographic examinations, as they have been so far, for the next 12 months, and annually thereafter.

Adolescent↗
PubMed1992

[Urologic neoplasms in AIDS].

Report on 2 cases of urological neoplasia in HIV positive patients. The first one is a renal adenocarcinoma in a heroin-abuser patient, of a type we have only found mentioned in the literature in 4 other cases. The second case was a disseminated Kaposi's sarcoma, the first symptom being a scrotum impairment and the biopsy suggested the diagnosis. This is believed to be an interesting communication considering the increasing number of anti-HIV antibodies carriers seen in our Units.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Identification of an extracytoplasmic region of H+,K(+)-ATPase labeled by a K(+)-competitive photoaffinity inhibitor.

The photoaffinity reagent 8-[(4-azidophenyl)-methoxy]-1-tritiomethyl-2, 3-dimethylimidazo-[1,2-alpha]pyridinium iodide ([3H]mDAZIP) has been synthesized and used to photoinactivate and label purified hog gastric H+,K(+)-ATPase. The specific (K(+)-sensitive) components of both photoinactivation and labeling showed dependences on inhibitor concentration consistent with covalent modification at an extracytoplasmic site of reversible K(+)-competitive binding in the dark. The maximum amount of specific labeling (1.2 nmol/mg) was similar to the number of phosphorylation sites measured (1.0 +/- 0.14 nmol/mg). Specific labeling was distributed 76% on the alpha chain, 18% on the beta chain, and 6% on undefined peptides. Various digestions with trypsin, protease V8, and thermolysin were employed to fragment the labeled enzyme. Gasphase sequencing of the radioactive peptides identified the major site of specific labeling to be within a region where only two stretches of amino acids (Leu105 to Ile126 and Leu139 to Phe155, designated H1 and H2, respectively) are predicted to span the membrane. This in turn suggested that the labeling site was located within or close to the proposed loop between them (Gln127 to Asn138). A computer-driven energy minimization protocol yielded a loop structure to which SCH 28080 (the parent structure of [3H]mDAZIP) could be docked. Conversely, modeling of the corresponding region of Na+,K(+)-ATPase (a homologous enzyme with much lower affinity for SCH 28080) yielded no apparent binding site. Similarities in the inhibition of H+,K(+)-ATPase by SCH 28080 and of Na+,K(+)-ATPase by ouabain lead to the hypothesis that, in each case, inhibitor binding to E2-P is associated with an increase in the hydrophobicity of the environment of the loop between H1 and H2.

Adenosine Triphosphatases↗
PubMed1991

Osmotic induction of gene osmC expression in Escherichia coli K12.

osmC, an osmotically inducible gene of Escherichia coli, was physically mapped on the bacterial chromosome, cloned on multicopy plasmids, and its product, OsmC, was identified as a 14 kDa protein in maxicells. The DNA sequence of the gene and its upstream region were determined. The sequence of an osmC-phoA gene fusion confirmed the osmC reading frame. A deletion of osmC from the E. coli chromosome was constructed by gene replacement, demonstrating that it is not an essential gene. The osmCp promoter region was subcloned and a lac operon fusion transcribed under osmCp control was constructed. The expression of this operon fusion demonstrated that osmC regulation occurs at the transcriptional level. S1 nuclease protection experiments and deletion analysis identified two overlapping promoters with transcription start sites separated by ten nucleotides. All the sequences necessary for osmotic regulation of both promoters are located within a 137 base-pair DNA fragment extending from position -95 to +42 with respect to the putative osmC translation start. Two deletions were obtained that abolish the functioning of the upstream promoter. Yet, under our experimental conditions, the subsequent expression of the osmC-lacZ fusion was equivalent to that obtained from the tandem promoters. Mutations leading to constitutive expression of osmC were selected. Two independent mutations were obtained, both affected osmZ, the gene encoding the histone-like protein H1.

Amino Acid Sequence↗
PubMed1991

Metacontrast with masks varying in spatial frequency and wavelength.

In a metacontrast masking paradigm, adult subjects were required to detect briefly presented target lines followed at various delays by a flanking mask varying in spatial frequency and wavelength. Detection accuracy, the dependent measure, was recorded as a function of the delay of the mask. The results showed that long wavelength masks produced maximum masking at a relatively short delay, while short wavelength masks produced maximum masking at a relatively long delay. Results are discussed within the framework of transient/sustained (magnocellular/parvocellular) theory of visual processing, and suggest that low spatial frequency channels respond with shorter latency and/or faster rise time to short wavelength stimuli, and high spatial frequency channels respond with greater sensitivity to long wavelength stimuli.

Adult↗
PubMed1991

Osmotic induction of the periplasmic trehalase in Escherichia coli K12: characterization of the treA gene promoter.

The Escherichia coli treA gene encodes an osmotically inducible periplasmic trehalase. A strain carrying a treA-lacZ transcriptional fusion was constructed. The beta-galactosidase activity produced in this strain growing exponentially in a medium of high osmotic pressure was 10-fold higher than that produced in a medium of low osmotic pressure, demonstrating that treA transcription is osmotically inducible. treA transcriptional induction depends neither on the presence of trehalase itself nor on the synthesis of cytoplasmic trehalose which occurs in response to osmotic stress in wild-type E. coli strains. The treA promoter was identified by S1 nuclease protection. Deletion analysis demonstrated that sequences sufficient for the osmotic induction lie downstream from nucleotide -40 with respect to the transcription start. Transcription initiation at treAp required the presence of a functional sigma 70 subunit of RNA polymerase. treA expression was increased in the presence of a mutation in osmZ, which was previously identified as leading to a partially constitutive expression of the osmotically inducible proU operon.

Amino Acid Sequence↗
PubMed1991

Interleukin 2 production in a family with systemic lupus erythematosus and a C4Q0 heterozygous inheritance.

Interleukin 2 production was studied in a family with systemic lupus erythematosus (SLE) and a C4Q0 heterozygous inheritance. Autoimmune manifestations seemed to be associated with the HLA haplotype containing the C4Q0 allele, which was shared by all four ill family members. Concentrations of interleukin 2, however, did not associate either with the haplotype or with the clinical or serological manifestations, as diminished concentrations of interleukin 2 were found in only two subjects with SLE. Thus the defect in this family seemed to be acquired rather than genetically conditioned.

Adolescent↗
PubMed1990

Characterization of a DNA binding protein of bacteriophage PRD1 involved in DNA replication.

Escherichia coli phage PRD1 protein P12, involved in PRD1 DNA replication in vivo, has been highly purified from E. coli cells harbouring a gene XII-containing plasmid. Protein P12 binds to single-stranded DNA as shown by gel retardation assays and nuclease protection experiments. Binding of protein P12 to single-stranded DNA increases about 14% the contour length of the DNA as revealed by electron microscopy. Binding to single-stranded DNA seems to be cooperative, and it is not sequence specific. Protein P12 also binds to double-stranded DNA although with an affinity 10 times lower than to single-stranded DNA. Using the in vitro phage phi 29 DNA replication system, it is shown that protein P12 stimulates the overall phi 29 DNA replication.

Coliphages↗
PubMed1990

Transcription of osmB, a gene encoding an Escherichia coli lipoprotein, is regulated by dual signals. Osmotic stress and stationary phase.

The osmB gene, which encodes an outer membrane lipoprotein, can be induced by both osmotic and growth phase signals. Construction of two transcriptional fusions, an osmB-lacZ fusion in single copy on the bacterial chromosome and an osmB-cat fusion carried on a multicopy plasmid, demonstrated that induction of osmB by hyperosmolarity and during the stationary phase of growth occurred at the level of transcription. Two transcription initiation sites were identified by RNase protection of in vivo message. The downstream P2 promoter is the primary site for regulation; the basal level of expression is initiated at P2 and transcription from P2 is induced by elevated osmolarity or upon reaching stationary phase. Transcription from the P1 promoter, 150 base pairs (bp) upstream of the P2 promoter, occurred only when both osmotic and growth phase signals were present simultaneously; that is, when cells growing in high osmolarity medium have reached stationary phase. Deletion analysis narrowed the sequences necessary for P2 regulation to the 42-bp region upstream from the transcription start site. A 7-bp sequence just upstream from the -35 region was identified as a cis-acting regulatory element essential for osmotic stimulation of osmB expression. A hexanucleotide sequence within this segment could form the left arm of a region of dyad symmetry, flanking the -35 region of the promoter. Stationary phase induction at P2 does not require the 7-bp element.

Bacterial Outer Membrane Proteins↗
PubMed1990

Location of the carbohydrates present in the HK-ATPase vesicles isolated from hog gastric mucosa.

The glycosylation of H+K(+)-ATPase vesicles isolated from hog gastric mucosa was investigated by various methods. Following protein separation on sodium dodecyl sulfate reducing gels and transfer to poly(vinyl difluoride) membranes, binding of concanavalin A was confined to the 94-kDa band which corresponds to the catalytic subunit. In contrast, wheat germ agglutinin binding occurred in a region below the 94-kDa subunit, corresponding to the 60-85-kDa region, and also to protein just above the catalytic subunit. Treatment with glycopeptidase F removed most of the concanavalin A staining and also the wheat germ agglutinin staining found below the 94-kDa region, but spared the higher molecular weight wheat germ agglutinin reactive material. During the deglycosylation experiments a protein of 35-kDa was produced. Sequencing analysis of V8 protease generated peptide fragments of the 35-kDa protein show at least 30% homology with the Na+K(+)-ATPase beta-subunits. Labeling of the carbohydrates by galactosyltransferase and [3H]uridine diphosphate-galactose showed that the sites of labeling were extracellular and were confined to the wheat germ agglutinin staining regions. Two molecular weight regions, below the 94-kDa region, of 60 and 85 kDa were identified. Electron microscopy using postembedding staining techniques showed that both concanavalin A and wheat germ agglutinin staining occurred on the extracellular face of the gastric vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1990

Nucleosome assembly in mammalian cell extracts before and after DNA replication.

Protein-free DNA in a cytosolic extract supplemented with SV40 large T-antigen (T-Ag), is assembled into chromatin structure when nuclear extract is added. This assembly was monitored by topoisomer formation, micrococcal nuclease digestion and psoralen crosslinking of the DNA. Plasmids containing SV40 sequences (ori- and ori+) were assembled into chromatin with similar efficiencies whether T-Ag was present or not. Approximately 50-80% of the number of nucleosomes in vivo could be assembled in vitro; however, the kinetics of assembly differed on replicated and unreplicated molecules. In replicative intermediates, nucleosomes were observed on both the pre-replicated and post-replicated portions. We conclude that the extent of nucleosome assembly in mammalian cell extracts is not dependent upon DNA replication, in contrast to previous suggestions. However, the highly sensitive psoralen assay revealed that DNA replication appears to facilitate precise folding of DNA in the nucleosome.

Animals↗
PubMed1990

The effects of spatial phase on reaction time to spatially filtered images.

Many studies of visual perception have used periodic stimuli such as sine-wave gratings and checkerboard patterns. It is well known that reaction time (RT) to such stimuli increases with increasing spatial frequency and decreasing contrast. While this is the case with periodic stimuli it is not clear that these relationships obtain for aperiodic stimuli such as natural scenes. A digitized image of an object (a vase) was submitted to two-dimensional Fourier analysis. Four pairs of spatial frequency band-limited images were created for each image. Each pair consisted of a normal-phase (NP) and a scrambled-phase (SP) version, with the magnitude spectrum and space-averaged luminance the same within each pair. Filter band-widths were 1 octave wide. Manual RT was measured for onset and offset of each spatially filtered image. Mean RT for SP images increased significantly with increasing spatial frequency, while no other significant differences were found with the NP images. This suggests that the temporal processing of complex, aperiodic images is influenced by the spatial frequency and contrast of local regions within the image, rather than by the space-averaged contrast of the entire image, and cannot be predicted by global estimates of contrast and spatial frequency.

Adult↗
PubMed1990

Simian virus 40 origin auxiliary sequences weakly facilitate T-antigen binding but strongly facilitate DNA unwinding.

The complete simian virus 40 (SV40) origin of DNA replication (ori) consists of a required core sequence flanked by two auxiliary sequences that together increase the rate of DNA replication in monkey cells about 25-fold. Using an extract of SV40-infected monkey cells that reproduced the effects of ori-auxiliary sequences on DNA replication, we examined the ability of ori-auxiliary sequences to facilitate binding of replication factors and to promote DNA unwinding. Although the replicationally active form of T antigen in these extracts had a strong affinity for ori-core, it had only a weak but specific affinity for ori-auxiliary sequences. Deletion of ori-auxiliary sequences reduced the affinity of ori-core for active T antigen by only 1.6-fold, consistent with the fact that saturating concentrations of T antigen in the cell extract did not reduce the stimulatory role of ori-auxiliary sequences in replication. In contrast, deletion of ori-auxiliary sequences reduced the efficiency of ori-specific, T-antigen-dependent DNA unwinding in cell extracts at least 15-fold. With only purified T antigen in the presence of topoisomerase I to unwind purified DNA, ori-auxiliary sequences strongly facilitated T-antigen-dependent DNA conformational changes consistent with melting the first 50 base pairs. Under these conditions, ori-auxiliary sequences had little effect on the binding of T antigen to DNA. Therefore, a primary role of ori-auxiliary sequences in DNA replication is to facilitate T-antigen-dependent DNA unwinding after the T-antigen preinitiation complex is bound to ori-core.

Animals↗
PubMed1990

The transfer of adaptation between actual and simulated rotary stimulation.

It is well known that continued exposure to motion environments leads to adaptation, but it is not clear whether such changes are specific to the particular type of motion experienced. The present investigation sought to evaluate the extent of transfer between real motion and visually-induced apparent motion. In addition, the direction of motion was varied and these two factors, mode of exposure and direction of rotation, were examined in a cross-adaptational design. Thirty-two subjects were pre- and posttested on measures of disorientation after active bodily rotation and visually-induced self-vection. Two groups received ten consecutive trials of active bodily rotation (clockwise or counter-clockwise) for 4 consecutive days. Two other groups received ten consecutive trials of visually-induced self-vection (clockwise or counter-clockwise) in a rotating drum for 4 consecutive days. During the exposure phase, dizziness and self-vection increased over trials for the groups exposed to the drum, while dizziness remained unchanged over trials for the groups exposed to bodily rotation. Repeated exposure to bodily rotation resulted in improved walking performance over trials and days. Subjects exposed to bodily rotation exhibited increased tolerance to visually-induced self-vection; however, exposure to visually-induced self-vection did not result in greater tolerance to bodily rotation. No support for directional specificity was evident.

Adaptation, Physiological↗
PubMed1989

Development of a bacteria-independent model of the multiple organ failure syndrome.

Criteria that allow definition of the multiple organ failure syndrome include pulmonary, hepatic, renal, and gut barrier dysfunction along with characteristic histopathologic changes. It has been difficult to study multiple organ failure due to lack of a satisfactory experimental model that would reproduce the pathophysiologic and histopathologic characteristics, would be stable enough to allow study over several days, and would be free of exogenous primary bacterial infection. We have studied pathophysiologic and histopathologic alterations in a potential model of multiple organ failure. Wistar rats received one of the following solutions by intraperitoneal injection: 4 mL of saline, 4 mL of mineral oil, or 1 mg per gram of body weight of zymosan A in 4 mL of mineral oil. Animals that received zymosan developed hypoxia, decreased creatinine clearance, and changes in hepatic microsomal cytochrome P450 content and aniline hydroxylase activity. Bacterial translocation occurred in the zymosan group. The lungs, liver, and kidneys of the animals that received zymosan exhibited histopathologic changes. We conclude that this model fulfills our criteria for a model of multiple organ failure.

Animals↗
PubMed1989

Analysis and DNA sequence of the osmoregulated treA gene encoding the periplasmic trehalase of Escherichia coli K12.

The treA gene of Escherichia coli K12 codes for a periplasmic trehalase that is induced by growth at high osmolarity. The position of treA within a cloned chromosomal DNA fragment was identified by subcloning of restriction fragments and analysis of the gene product in minicells. The nucleotide sequence of the treA coding region as well as its upstream control region was determined. The treA gene consists of 1695 bp encoding 565 amino acids. The amino-terminus of the mature trehalase was found to begin with the amino acid Glu at position 31 of the open reading frame. The first 30 amino acids resemble a typical signal sequence, consistent with trehalase being a secreted periplasmic enzyme. Two previously isolated phoA fusions to the osmA gene were transferred by homologous recombination on to a treA-containing plasmid and found to be within treA. Analysis of the hybrid genes and their gene products aided the localization of treA and the determination of its direction of transcription within the cloned chromosomal segment. The treA-phoA fusions encoded hybrid proteins which could be found in the periplasm. We found that at high osmolarity the normal pathway for the uptake and utilization of trehalose is blocked. Therefore, the function of the periplasmic trehalase is to provide the cell with the ability to utilize trehalose at high osmolarity by splitting it into glucose molecules that can subsequently be taken up by the phosphotransferase-mediated uptake system.

Amino Acid Sequence↗