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Biomedical subjects

R E Cuellar

Publications and source records attributed to R E Cuellar.

12 recordsLinked to original sources
PubMed1990

Gastrointestinal tract hemorrhage. The value of a nasogastric aspirate.

A bloody nasogastric aspirate is believed to imply active upper gastrointestinal tract bleeding, while a nonbloody yellow-green nasogastric aspirate that contains duodenal secretions suggests the absence of bleeding proximal to the ligament of Treitz. To validate these beliefs, physicians were asked to predict the presence of active gastrointestinal tract bleeding and whether bile was present in a nasogastric aspirate obtained immediately before endoscopy in 73 episodes of bleeding in 62 patients. A relationship was found between the physician's assessment of the presence of active bleeding demonstrated endoscopically and the appearance of the nasogastric aspirate. However, the sensitivity and specificity were low (79% and 55%, respectively). No association between the assessment of bile in the nasogastric aspirate and the presence of bile acids was demonstrated. These data do not support the placement of a nasogastric tube to determine whether or not a patient is bleeding, the location of the bleeding, and whether endoscopy should be performed.

Bile↗
PubMed1988

Aggregation of lysine-containing zeins into protein bodies in Xenopus oocytes.

Zeins, the storage proteins of maize, are totally lacking in the essential amino acids lysine and tryptophan. Lysine codons and lysine- and tryptophan-encoding oligonucleotides were introduced at several positions into a 19-kilodalton zein complementary DNA by oligonucleotide-mediated mutagenesis. A 450-base pair open reading frame from a simian virus 40 (SV40) coat protein was also engineered into the zein coding region. Messenger RNAs for the modified zeins were synthesized in vitro with an SP6 RNA polymerase system and injected into Xenopus laevis oocytes. The modifications did not affect the translation, signal peptide cleavage, or stability of the zeins. The ability of the modified zeins to assemble into structures similar to maize protein bodies was assayed by two criteria: assembly into membrane-bound vesicles resistant to exogenously added protease, and ability to self-aggregate into dense structures. All of the modified zeins were membrane-bound; only the one containing a 17-kilodalton SV40 protein fragment was unable to aggregate. These findings suggest that it may be possible to create high-lysine corn by genetic engineering.

Amino Acid Sequence↗
PubMed1988

Upper gastrointestinal tract dysfunction in bulimia.

Bulimia nervosa is a health problem of increasing magnitude that is estimated to affect 2-5% of the American adolescent and young adult female population. Because of the magnitude of this clinical problem and because of the importance of the upper gastrointestinal tract in its expression, a intradepartmental program of health care for patients affected with the disease was initiated. Eleven consecutive symptomatic bulimic individuals have been evaluated jointly by the gastroenterology and the psychiatry departments of the University of Pittsburgh. Five of these 11 individuals were found to have clinically important upper gastrointestinal pathology including ulcerative esophagitis, erosive gastritis, duodenal ulcer, and delayed gastric emptying. These gastrointestinal conditions could have been either a result of or have contributed to the symptomatology of these five patients. These data suggest that bulimic subjects have clinically important gastroenterological disease processes that require specific diagnosis and treatment independent of the psychiatric treatment provided for the bulimic condition.

Adult↗
PubMed1988

Cytomegalovirus infection of the upper gastrointestinal tract before and after liver transplantation.

The prevalence of upper gastrointestinal CMV infection was determined in 90 adult transplant patients: 54 were evaluated prior to orthotopic liver transplantation (OLTx), while 36 were evaluated one to six weeks after OLTx. Upper gastrointestinal endoscopy, with biopsies of the stomach and duodenum for viral culture and histopathologic examination, was performed on each subject. Those without esophageal varices had their esophagus biopsied also for viral cultures and histopathologic examination. In addition, a gastric brushing for cytologic examination was obtained on all patients. All 90 patients studied were known to be CMV-sero-positive prior to transplantation. Therefore all infections were considered to be reactivation infections. Gastrointestinal CMV infection was more common in patients studied post-OLTx (33%) than it was in those studied pre-OLTx (2%) (P less than 0.001). The presence of gastrointestinal CMV infection was associated with a decreased T lymphocyte helper/suppressor ratio in peripheral blood. CMV duodenal infections were associated with the presence of endoscopic and histologic inflammation. Of the various diagnostic methods utilized, viral cultures of intestinal tissue were found to be the most useful in establishing a diagnosis of infection.

Cytomegalovirus Infections↗
PubMed1986

Synthetic oligonucleotide tails inhibit in vitro and in vivo translation of SP6 transcripts of maize zein cDNA clones.

A maize zein cDNA clone was used to synthesize mRNA with the SP6 in vitro transcription system. Although we obtained full-length transcripts of the cDNA sequence, these were inefficient templates for protein synthesis. Removal of the 5' oligo(G) sequence that was synthesized during the cDNA cloning procedure allowed efficient translation of the mRNAs in a wheat germ cell-free protein synthesis system or in Xenopus laevis oocytes. The alteration in translational efficiency did not result from an interaction of the 5' oligo(G) homopolymer tail with the 3' oligo(C) sequence, as transcripts with or without the oligo(C) tail were translated similarly in both protein synthesis systems. Ribosome interaction with the mRNA may be affected due either to the secondary structure of the oligo(G) sequence itself, or an unusual secondary structure between the oligo(G) sequence and another region in the mRNA. Synthetic oligonucleotides at the 5' end of cloned cDNA sequences may generally be inhibitory for translation of mRNAs transcribed in vitro.

Animals↗
PubMed1985

Antitermination is required for readthrough transcription of the maize rbcL gene by a bacteriophage promoter in Escherichia coli.

Sequences upstream of the 5' end of the rbcL gene in maize chloroplast fragment Bam 9, have a polar effect on the expression of rbcL from an external upstream bacteriophage PL promoter in Escherichia coli. This polarity can be suppressed by the bacteriophage transcription antitermination protein N or Q. The requirement for transcription antitermination is abolished if DNA upstream of rbcL is removed by a deletion. We have also investigated the ability of RNA polymerase initiating transcription at PL in the presence of N to transcribe through the normal rbcL transcription terminator and into sequences beyond. RNA polymerase initiating at PL can traverse rbcL and its 5' and 3'-flanking regions in the presence of N.

Base Sequence↗
PubMed1978

DNA sequence organization in the pea genome.

The reassociation kinetics of pea (Pisum sativum L.) DNA fragments (300 nucleotides) were measured with hydroxylapatite. The most slowly reassociating fragments do so with a rate constant of 2 X 10(-4) L mol-1s-1, as determined from experiments with total DNA as well as with a tracer enriched for slowly renaturing sequences. This rate is about 1000 times slower than that observed for Escherichia coli DNA included as an internal kinetic standard, indicating a kinetic complexity of 4.5 X 10(9) nucleotide pairs or 4.6 pg of DNA per haploid nucleus. This estimate is in good agreement with previous chemical and cytophotometric measurements. The majority (85%) of the 300 nucleotide fragments contain repetitive sequences. While the reassociation of repetitive DNA could be modeled with two theoretical second-order components, the data did not specify a unique solution. The reassociation kinetics of isolated high- and low-frequency fractions indicate that repetitive sequence families in pea DNA probably cover a broad range of frequencies ranging from 100 to 10 000 or more copies per haploid genome. Single-copy sequences account for about 30% of the DNA, but because of extensive interpersion of repetitive sequences only about 15% of 300 nucleotide fragments reassociate with single-copy kinetics. From studies of hydroxylapatite binding as a function of fragment length, we conclude that the major class of single-copy sequences has a modal length of about 300 nucleotides. Long tracer reassociation kinetics indicate that sequences with an apparent repetition frequency of about 10 000 copies are interspersed at intervals of less than 1300 nucleotides throughout 75% of the genome. At a detection limit of about 3%, we find no single-copy sequences longer than 1000 nucleotides.

DNA↗
PubMed1978

Application of higher derivative techniques to analysis of high-resolution thermal denaturation profiles of reassociated repetitive DNA.

We have analyzed high-resolution denaturation profiles of reassociated repetitive DNA sequences by using a combination of higher derivative analysis and curve-fitting techniques. Procedures originally used for resolution of components in complex absorption spectra were found to be applicable to high-resolution analysis of melting profiles of reassociated repetitive DNA sequences from pea DNA. Under conditions that eliminate the base composition effect on thermal stability (2.4 M tetraethylammonium chloride), such an anlysis can distinquish "thermal classes" of repetitive DNA duplexes exhibiting different amounts of base pair mismatch. Only a single thermal class is observed in reassociated Escherichia coli DNA whereas at least five classes can be reproducibly distinguished in pea and mung bean DNAs.

Base Sequence↗
PubMedDate not supplied

The possible occurrence of "alcoholic hepatitis" in a patient with bulimia in the absence of diagnosable alcoholism.

A case of a 20-yr-old female with possible "alcoholic hepatitis" and a mixed micro/macronodular cirrhosis occurring in association with overt bulimia and a history of anorexia nervosa, but without any objective evidence of either alcoholism or alcohol abuse, is reported. The possible factors that may have contributed, either alone or in combination, to produce this unusual occurrence are discussed.

Adult↗