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Biomedical subjects

W A Walker

Publications and source records attributed to W A Walker.

At least 19 recordsLinked to original sources
PubMed1992

Migration of intravascular balloon after percutaneous embolotherapy of varicocele.

Migration of an intravascular balloon following embolic therapy for varicocele is uncommon. A third case is reported of migration of a left internal spermatic vein embolic balloon to the right lung in an otherwise healthy twenty-five-year-old male who was treated for a symptomatic left varicocele. The patient, a student naval aviator in the jet pilot program, has had his career adversely affected by this complication.

Adult↗
PubMed1992

Expression and developmental regulation of Na+,K+ adenosine triphosphatase in the rat small intestine.

The Na+,K(+)-ATPase ion pump plays a critical role in fluid and electrolyte physiology of the small intestine. Here we show that, of the three known alpha isotypes (alpha 1, alpha 2, and alpha 3) of the sodium pump found in the rat, only alpha 1 is expressed in the small intestine. The expression of this isotype, considered at the level of mRNA, is under developmental control, with the adult intestine exhibiting approximately a threefold increase in alpha 1 message over the neonate. Cortisone treatment of the neonate results in near-adult levels of alpha 1 mRNA expression. An increase in the abundance of alpha 1 isotype parallels the changes in its mRNA expression. beta subunit mRNA is expressed coordinately with the alpha 1 subunit mRNA. A four- to five-fold rise in the Na+,K(+)-ATPase activity is also developmentally induced.

Age Factors↗
PubMed1992

Diminished Clostridium difficile toxin A sensitivity in newborn rabbit ileum is associated with decreased toxin A receptor.

Human infants are relatively resistant to Clostridium difficile-associated diarrhea and colitis compared to adults. In that toxin A is the major cause of intestinal damage with this organism, we compared toxin A receptor binding and biological effects in newborn vs adult rabbit ileum. Purified toxin A (M(r) 308 kD) was labeled with tritium or biotin with full retention of biologic activity. Appearance of specific toxin A brush border (BB) binding was strongly age dependent with minimal [3H]toxin A specific binding at 2 and 5 d of life, followed by gradual increase in binding to reach adult levels at 90 d. Absence of toxin A binding sites in newborn and presence in adult rabbits was confirmed by immunohistochemical studies using biotinylated toxin A. Toxin A (50 ng to 20 micrograms/ml) inhibited protein synthesis in 90-d-old rabbit ileal loops in a dose-dependent fashion. In contrast, inhibition of protein synthesis in 5-d-old rabbit ileum occurred only at the highest toxin A doses (5 and 20 micrograms/ml) and at all doses tested was significantly less than the adult rabbit ileum. In addition, toxin A (5 micrograms/ml) caused severe mucosal damage in adult rabbit ileal explants but had no discernable morphologic effect on 5-d-old rabbit intestine. Our data indicate that newborn rabbit intestine lacks BB receptors for toxin A. The absence of the high-affinity BB receptor for toxin A in the newborn period may explain lack of biologic responsiveness to purified toxin, and the absence of disease in human infants infected with this pathogen.

Age Factors↗
PubMed1992

The mucosal barrier, IgE-mediated gastrointestinal events, and eosinophilic gastroenteritis.

The "mucosal barrier" plays an important role in regulating immune responses in the gastrointestinal tract. Although the precise mechanisms controlling mucosal immune responses have not been defined, when an abnormal response such as IgE production is initiated, a variety of complex and incompletely understood pathophysiologic events occur and can result in gastrointestinal pathology. This article attempts to present the complexity of such abnormal responses. Although more questions have emerged than were answered, in recent years our knowledge of the pathophysiology of IgE-mediated events in the gastrointestinal tract has advanced significantly. Our understanding of the pathophysiology of these events will ultimately allow the development of more directed and effective therapeutic interventions for allergic gastrointestinal diseases. In addition, through further clinical and basic research, we should begin to unravel the more enigmatic conditions affecting the gastrointestinal tract, such as EG.

Acute Disease↗
PubMed1991

Delayed chest wall pain due to sternal wire sutures.

This report describes 18 patients with disabling chest wall pain due to one or more sternal wire sutures. The pain occurred from 2 to 84 months after a median sternotomy. The pain was described either as sharp and stabbing or as a deep-seated ache. The involved wires had an exaggerated fibrous tissue reaction surrounding the twisted portion. The adjacent noninvolved wires had minimal reaction. In the last 7 patients, serial sections of the fibrous tissue revealed entrapment of one or more sensory nerve fibers. In 6 of the 7 electrical potentials were measured and found to be elevated, indicating wire damage during twisting. Ferroxyl tests confirmed the collection of iron ions at this anodic point as a result of corrosion. Removal of the involved wires and the fibrous tissue surrounding this anodic point relieved the symptoms of pain and tenderness resulting from entrapped sensory nerves.

Bone Wires↗
PubMed1991

Primary Aspergillus osteomyelitis of the sternum.

We report 2 cases of primary sternal osteomyelitis caused by Aspergillus; previously reported cases have been complications of sternotomy. Both patients were healthy young men with recent intravenous drug abuse. No other focus or predisposing factors were found. Both were treated with partial sternectomy and chondrectomy; 1 received long-term amphotericin B therapy. Both are doing well 2 1/2 years after operation. Drug usage, acquired immunodeficiency syndrome, and medical immunosuppression may lead to other cases.

Adult↗
PubMed1991

Thermally induced pulpalgia in endodontically treated teeth.

Two cases of thermally induced pulpalgia in teeth previously endodontically treated are presented. Reproduction of the patient's chief complaint was the key to identifying the teeth involved. In both cases, the pulpalgia was stimulated by heat. After locating and treating an unfilled canal, the teeth have remained asymptomatic. Possible explanations for this occurrence are discussed.

Adult↗
PubMed1991

Rapid development of vitamin K deficiency in an adolescent boy receiving total parenteral nutrition following bone marrow transplantation.

In this case report the development of a vitamin K deficiency in a neutropenic adolescent receiving parenteral nutrition following bone marrow transplantation is described. The parenteral nutrition solution did not provide vitamin K and the patient had been receiving oral antibiotics prior to and during use of the intravenous feeding. Oral intake was minimal. Standard adult oral and intravenous multivitamin preparations for use in individuals older than 11 years do not routinely contain this vitamin. The function of vitamin K and causes for development of a deficiency are reviewed. Recommended intakes and guidelines for supplementation are also discussed.

Adolescent↗
PubMed1991

Parenteral protein-sparing modified fast in an obese adolescent with Prader-Willi syndrome.

A ventilator-dependent, extremely obese adolescent patient with Prader-Willi syndrome was nutritionally managed using a parenteral, protein-sparing modified fast. A solution containing only amino acids, electrolytes, vitamins, and macro- and micro-minerals helped create a ketotic state and facilitate weaning from the ventilator. This case demonstrates an unusual strategy for achieving weight loss and the challenge to provide adequate protein intake while limiting fluid intake.

Adolescent↗
PubMed1991

Celiac disease.

Explore the source record for details and available documents.

Celiac Disease↗
PubMed1990

Medical management of acute traumatic rupture of the aorta.

Surgical reconstruction is the treatment for acute traumatic aortic rupture and should be accomplished immediately in most patients. In patients in whom concomitant injuries or the development of life-threatening complications preclude safe and successful aortic reconstruction, pharmacological intervention to reduce the risk of free aortic rupture may be considered. Surgical reconstruction can then be more safely performed under controlled elective circumstances.

Abdominal Injuries↗
PubMed1990

Uptake and transport of epidermal growth factor by the small intestinal epithelium of the fetal rat.

Epidermal growth factor may play an important part in postnatal gastrointestinal development. However, little is known of its role prenatally. The aim of this study was to detect epidermal growth factor in amniotic fluid and to study its uptake and transfer across the epithelium of fetal rat small intestine. Anesthetized 20-day gestation rats underwent caesarean section. Three fetuses were exteriorized, their abdomens were opened, and ligated loops of proximal and distal small intestine were infused with 100 micrograms epidermal growth factor. Infused segments were removed 30 min later and processed for electron microscopy, and tissue was embedded in LR gold resin. Sections were treated with rabbit anti-rat epidermal growth factor antibody, followed by 5 nm gold-labeled goat anti-rabbit immunoglobulin before staining. Epidermal growth factor was measured in amniotic fluid by radioimmunoassay. In the proximal and distal small intestine epidermal growth factor was found membrane-associated along the luminal surface of microvilli, within apical invaginations and endosomal compartments, free from the membrane in multivesicular bodies, within large clear vesicles, basal vesicles and in association with the basolateral membrane and beyond. Epidermal growth factor was found in amniotic fluid at a concentration of 0.38 +/- 0.07 (SD) ng/ml. This study shows that epidermal growth factor is present in amniotic fluid and is transported across the epithelium of fetal rats by an endocytotic process in both the upper and lower small intestine. It is likely that amniotic fluid epidermal growth factor plays a part in intestinal mucosal development, and may be active systemically after transepithelial passage in utero.

Amniotic Fluid↗