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Biomedical subjects

P O'Brien

Publications and source records attributed to P O'Brien.

At least 181 records · Page 10Linked to original sources
PubMed1985

Clinical and neuropathological criteria for the diagnosis and staging of diabetic polyneuropathy.

Scored symptoms, neurological deficits, detection threshold of cutaneous sensation and parameters of nerve conduction were compared with quantitated neuropathological abnormalities in the sural nerve in 47 healthy subjects and 36 diabetic patients, 32 with and 4 without neuropathy. The fifth percentile line of a new Index of Pathology, which combines loss of myelinated fibres and abnormality of the remaining fibres, was found to provide a sensitive and reliable minimum neuropathological criterion for the diagnosis of polyneuropathy. Abnormality, as assessed by two clinical evaluations, similarly separated healthy subjects and diabetic patients into those with and without neuropathy. For the detection of diabetic polyneuropathy, vibration sense was more sensitive than touch-pressure or thermal cooling. Abnormalities of nerve conduction were found to be both sensitive and reliable in the detection of polyneuropathy. Velocity was most frequently abnormal, but only slightly more often than F wave latency and amplitude. We conclude that abnormality, as judged independently from two different types of evaluation, provides a sensitive and reliable minimal criterion for the diagnosis of neuropathy. Although symptoms, neurological deficits and abnormalities of nerve conduction are statistically associated, they should be evaluated separately to provide adequate characterization.

Adolescent↗
PubMed1985

The Fontan procedure.

The Fontan procedure has afforded improved surgical repair for several complex congenital cardiac defects, including tricuspid atresia and single ventricle. Through surgical creation of a connection between the RA and the RV or PA, adequate pulmonary perfusion can be achieved without an RV. Although it is not an anatomic connection, the Fontan procedure is a more physiologic approach than the previously used shunt procedures. Systemic venous return and PVR are effectively separated within the heart, pulmonary blood flow is assured through an RA-to-PA connection, and ventricular volume overload is avoided. The procedure has been effective in relieving cyanosis and has resulted in improved levels of exercise tolerance after surgery.

Blood Vessel Prosthesis↗
PubMed1984

Increased incidence of cervical and vaginal dysplasia in 3,980 diethylstilbestrol-exposed young women. Experience of the National Collaborative Diethylstilbestrol Adenosis Project.

The incidence rates of dysplasia and carcinoma in situ (CIS) of the cervix and vagina were determined in 3,980 young women exposed prenatally to diethylstilbestrol. Strict criteria were developed to minimize selection bias among the subset of 744 pairs of matched exposed and unexposed (control) cohort participants, all of whom were identified through review of prenatal obstetrical records. A high degree of compliance was achieved throughout the seven-year study period since in each group about 90% of the women remained as active participants, kept 77% of the annual anniversary examinations, and had separate Papanicolaou smears of the cervix and vagina performed in 99% of the anniversary examinations. The incidence rate for dysplasia and CIS was significantly higher in the women exposed to diethylstilbestrol than in those not exposed in the matched cohort (15.7 v 7.9 cases per 1,000 person-years of follow-up). The rates were higher in the exposed women if squamous metaplasia extended to the outer half of the cervix or onto the vagina. In other respects, the matched cohorts were strikingly similar.

Adult↗
PubMed1984

Identification of specific carboxylate groups on adrenodoxin that are involved in the interaction with adrenodoxin reductase.

Modification of bovine adrenodoxin with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) dramatically inhibited the reaction with adrenodoxin reductase (EC 1.18.1.2). The modification did not cause any change in the visible spectrum of adrenodoxin, indicating that the iron-sulfur center was not perturbed. Furthermore, the anomalous fluorescence of Tyr 82 was not changed in either intensity or wavelength. The inhibition was accompanied by the covalent incorporation of 14C-labeled EDC into adrenodoxin. The sites modified by EDC were determined by hydrolyzing adrenodoxin with either trypsin or Staphylococcus aureus protease and separating the resulting peptides by reverse phase high pressure liquid chromatography. The major carboxyl groups modified were found to be at Glu 74, Asp 79, and Asp 86, which are located in a sequence containing a high negative charge density. We propose that the conversion of negatively charged carboxylate groups at these residues to bulky, positively charged EDC-carboxyl groups inhibits the reaction with the reductase. EDC was also found to cross-link adrenodoxin to cytochrome c in yields up to 90%. The cross-links were found to involve the formation of amide linkages between carboxyl groups on adrenodoxin and the lysine amino groups surrounding the heme crevice of cytochrome c.

Adrenodoxin↗
PubMed1984

Low forestomach acidity in the rat and the role of the gastric bolus.

pH measurements were recorded from the mucosal surfaces of the rat forestomach and glandular stomach following stimulation of acid-secretion by pentagastrin. Animals containing a normal gastric bolus showed lower forestomach acidity (pH 4.3, cf. 3.2) as did coprophagic animals that contained a fecal gastric bolus (pH 6.0, cf. 3.6). Animals without a gastric bolus showed higher forestomach acidity (pH 2.3, cf. 3.0). It is concluded that the presence of a food bolus is prerequisite to maintenance of lower forestomach acidity in rats.

Animals↗
PubMed1984

Pneumomediastinum and retropneumoperitoneum: an unusual complication of syrup-of-ipecac-induced emesis.

A young woman returned to the emergency department two hours after discharge because of persistent vomiting and chest pain. Six hours earlier she had received syrup of ipecac to induce emesis following a drug overdose. Radiologic examination in the emergency department revealed pneumomediastinum and retropneumoperitoneum. A nasogastric tube was inserted in the emergency department. The patient was admitted to the ICU and placed on prophylactic antibiotics. Barium and gastrograffin esophagrams revealed no evidence of extravasation. Gastrointestinal endoscopy showed distal esophagitis. Gastroscopy and duodenoscopy were unremarkable. The patient did well following discharge.

Adolescent↗
PubMed1984

Effect of experimental dysthyroidism on the enzymatic character of the diaphragm.

This study examined the effects of long-term experimental dysthyroidism on the enzymatic character of the costal diaphragm and selected respiratory parameters. Costal diaphragms from thyroidectomized (TX), euthyroid (EU), and hyperthyroid (HT) male albino rats were used. HT was induced by subcutaneous injections of triiodothyronine on alternate days for 6 wk. Minute ventilation was greater for the HT (70%) compared with the TX rats. The enzymatic potentials of glycolysis (28%), tricarboxylic acid cycle (30%), and fatty acid oxidation (16%) were significantly increased in the HT diaphragms, whereas the potentials were lower by a similar relative extent in the TX diaphragms. The proportion of alkali-labile fibers were greater in the TX and lower in the HT diaphragm. The shifts in heart and muscle lactate dehydrogenase isoenzyme activities were consistent with the fiber type changes. These findings show that dysthyroidism modifies the overall enzymatic capacity of the diaphragm (i.e., glycolysis, tricarboxylic acid cycle, and fatty acid oxidation) along with the proportion of alkali-labile to alkali-stable fiber types. These enzymatic changes are similar to those resulting from exercise training, tracheal banding, streptozotocin diabetes, and emphysema.

Animals↗
PubMed1984

Spatial pattern of nerve fiber abnormality indicative of pathologic mechanism.

Estimates of the number, density, and size distribution of myelinated fibers at selected levels of roots, spinal tracts, and sampled levels of peripheral nerves may be used in the detection and characterization of alterations of motor, sensory, and autonomic neurons and their axons with development, aging and disease. Use of imaging techniques, now available, increases the reliability, versatility, and speed of such analysis. In this study, the authors evaluated the spatial pattern of fibers in sampled frames and contour areas of transverse sections of nerve fascicles, utilizing, the coefficient of variation and index of dispersion (ID), the latter extensively employed by plant ecologists. The ID was used for recognization of increased, normal, or decreased variability of density within fascicles, between fascicles, and between nerves in health and in various experimental neuropathies. In addition, various morphometric measurements were made in transverse sections at defined levels along the hind limb nerves of rats in acute and chronic ischemia, after rhizotomy and in galactose neuropathy. These stereomorphometric studies, emphasizing the number, size, shape, and spatial pattern of fibers, revealed differences among experimental neuropathies and may be found to be helpful in the characterization and prediction of pathologic mechanisms in neuropathies of unknown cause. Specifically, these approaches could be used for study of whether fiber loss in human diabetic neuropathy is multifocal and determination of the levels of such losses.

Acute Disease↗
PubMed1984

Surgical repair of cyanotic cardiac defects in young adults. The Fontan procedure and use of the extracardiac valved conduit.

Improvement in the health status of young adults with complex cyanotic congenital cardiac defects has been realized with recent advances in cardiovascular surgical techniques. The Fontan procedure and its modifications have allowed physiologic correction of tricuspid atresia by separating the pulmonary and systemic circulations and creating a direct connection from right atrium to pulmonary artery. The extracardiac valved conduit has been successfully used in the repair of pulmonary atresia with ventricular septal defect, and the triad of transposition of the great vessels, ventricular septal defect, and pulmonary stenosis. Nursing implications for the care of these patients in the postoperative period and their long-term management has been addressed. Advances in surgical techniques have brought these anomalies into the realm of surgical repair and have increased the life expectancy of these patients, and thus more patients with these cardiac defects will be seen in adult cardiology settings.

Adult↗
PubMed1984

Mucosal microvascular architecture of the fundus and body of human stomach.

Vascular casts of human oxyntic mucosa, examined by scanning electron microscopy, revealed that (a) arterial breakup occurs only at the submucosal aspect of the mucosa, there being no arterial vessels further into the mucosa and (b) mucosal capillaries drain into the infrequent mucosal venules only in the most luminal region of the lamina propria immediately underlying the surface mucus cells; the mucosal venules do not receive capillary tributaries deeper within the mucosa. Thus, blood flow in the mucosal exchange vessels can only occur in a unidirectional fashion, from the serosal to the luminal aspect. Using transmission electron microscopy, an often intimate association was seen between the fenestrated mucosal capillaries and parietal cells. These findings are together incorporated into a hypothesis that proposes vascular transport of HCO3-, released interstitially by secreting parietal cells, from deep within the mucosa toward the surface epithelium, thereby assisting gastric mucosal defense against luminal acid.

Arterioles↗
PubMed1983

Inhibition of gastric acid secretion in the gastric brooding frog, Rheobatrachus silus.

The female gastric brooding frog Rheobatrachus silus broods its young in its stomach. A substance that inhibits gastric acid secretion in a toad stomach preparation in vitro appears to be secreted by the developing young. This substance has been identified as prostaglandin E2. Rheobatrachus silus may thus have developed a mechanism whereby prostaglandin secreted by the larvae inhibits acid secretion in the stomach of the female until the larvae have completed development and emerged as juvenile frogs by way of the female's mouth.

Animals↗
PubMed1983

Fatal disseminated cytomegalovirus infection in an apparently normal adult.

An ostensibly normal 43-year-old man had intermittent fever, erythema multiforme, and leukopenia that evolved into fulminant hepatic and bone marrow necrosis. The cause of his illness was compatible with cytomegalovirus (CMV) infection since there was a fourfold increase in immunofluorescent antibody titer. This report suggests that CMV can produce a rapidly progressive and overwhelming infection in an apparently healthy adult.

Adult↗
PubMed1983

The microvasculature and gastric luminal pH of the forestomach of the rat: a comparison with the glandular stomach.

The microvasculature of the rat forestomach was compared with that of the glandular stomach using scanning electron microscopy of vascular corrosion casts and conventional transmission electron microscopy. The forestomach stratified mucosa is relatively poorly vascularized, having a simple 2 dimensional array of continuous capillaries located subepithelially. This contrasts with the extensive mucosal microvascular network of the glandular stomach, where fenestrated capillaries are closer to adjacent cells. pH measurements were taken at the mid-forestomach luminal surface and midfundic luminal surface of the glandular stomach. The H+ concentration was 200 x lower at the forestomach luminal surface. There was always food within the stomach. The pH of the food bolus, which extended throughout the stomach, reflected the pH of the adjacent mucosa. Because of their microvascular differences, the portal transport of HCO3- purported to protect the glandular mucosa from luminal acidity cannot operate at the forestomach mucosa. We speculate that the low forestomach acidity results from the buffering action of the food bolus and that the anatomically distinct dividing ridge restricts direct access of fundic secretions to the forestomach mucosa.

Animals↗
PubMed1982

Cytotoxicity of cancer patient's macrophages for tumor cells.

Monocyte derived macrophages were isolated from the peripheral blood of 66 patients with either breast, colon, gynecological or hematological cancers. The macrophages from the breast and gynecologic cancer patients generally did not acquire enhanced cytotoxicity for human tumor cells after incubation with bacterial lipopolysaccharide (LPS). However, when the macrophages isolated from colon and hematologic cancer patients were studied, more than 50% of these patients possessed cytotoxic macrophages. LPS induced macrophage mediated cytotoxicity was also found to be inhibited by factors present in many cancer patient's plasma. Twenty-three of the 50 cancer patients studied possessed a plasma inhibitor capable of suppressing macrophage mediated cytotoxicity by more than 50%. Furthermore, of these 50 patients, 47 were incapable of killing the tumor cells in vitro either because they possessed nonresponsive macrophages and/or they possessed a plasma inhibitory factor. Thus, although macrophage cytotoxic function may be normal in some patients with cancer, cytotoxicity may be inhibited in some patients by factors in autologous plasma thereby rendering the macrophages ineffective in vivo.

Adenocarcinoma↗
PubMed1982

Allele frequencies in a multidimensional Wright-Fisher model with general mutation.

A formula is obtained for the probability that two genes at a single locus, sampled at random from a population at time t, are of particular types. The model assumed is a diffusion approximation to a neutral Wright-Fisher model in which mutation is general and not necessarily symmetric. An example is given of a population in which one allele has a high mutation rate, and the others have an equal, low mutation rate. The matrix Q, with elements given by the probability of sampling two alleles of particular types, is calculated exactly and approximately for this case. A formula is given for the distribution of the number of segregating sites occurring in two randomly sampled finite sequences of completely linked sites, with general mutation at a site and identical mutation structure between sites.

Alleles↗