Biomedical subjects
Publications and source records attributed to L Barrett.
Distal innominate artery injury secondary to blunt trauma had not previously been reported. We present a case of distal innominate artery transection associated with a cervical spine dislocation. A mechanism for this unusual vascular injury is proposed. An organized diagnostic and treatment plan is emphasized.
The partial sequence of a gene encoding the COOH terminus of a protein of apparent molecular weight of 160 kD associated with the flagellum of trypomastigotes of Trypanosoma cruzi (FL-160 now renamed to FL-160-1) has been previously reported. The COOH terminus of FL-160-1 has an epitope, defined by 12 amino acids, which molecularly miMics a nervous tissue antigen of 48 kD found in myenteric plexus, sciatic nerve, and a subset of cells in the central nervous system. We now report that FL-160 is a family of highly related genes. The sequence has been determined for the entire open reading frame (ORF) of one of the members of the FL-160 gene family (FL-160-2) and three other partial ORFs. Sequence analysis reveals the various members of the FL-160 gene family to be approximately 80% homologous in the predicted amino acid sequence, but all retain the 12-amino acid molecular mimicry epitope on the COOH terminus. Comparison of the sequence of FL-160-2 to other sequences demonstrates amino acid homology to bacterial sialidase (27%), members of the SA85 gene family (25-30%) and the shed acute-phase antigen/neuraminidase/trans-sialidase gene family (25-30%). Quantitative hybridization at high stringency suggests 750 copies of FL-160 are present in the DNA of each parasite. Reverse transcription and sequence analysis demonstrates that at least five of the members of the FL-160 gene family are transcribed. The NH2 terminus of one of the FL-160 gene products was expressed and antibodies prepared. Antibodies directed to either the COOH or the NH2 terminus of FL-160 bind a 160-kD T. cruzi protein. Both antibodies bind the surface membrane in the flagellar pocket of the trypomastigote. Antibodies to the NH2 terminus bind epineurium and scattered linear densities in sciatic nerve in a pattern distinct from the pattern with antibodies to the COOH terminus. Thus, there are at least two distinct molecular mimicry epitopes on the FL-160 molecule and both mimic epitopes found in nervous tissues. FL-160 may be involved in the generation of autoimmunity to nervous tissues by molecular mimicry, observed in chronic Chagas' disease.
Cysticercosis, a sometimes fatal ailment caused by larvae of the pork tapeworm Taenia solium, became a reportable disease in California in 1989. During the first year, from 1 April 1989 through 31 March 1990, 134 cases were reported to the California Department of Health Services. All of the 112 patients for whom laboratory diagnostic test data were obtained had neurocysticercosis. Nearly all (117) of the 127 patients whose race and ethnic background were known had a Hispanic background, and most of the 112 patients whose country of birth or prior residence was known had immigrated from T. solium-endemic countries. However, three of 11 patients born in the United States said they had never traveled outside the country, and it appears possible that indigenous transmission has been occurring. These findings affirm that neurocysticercosis should be included in the differential diagnosis of neurologic symptoms in patients who have immigrated from or traveled to T. solium-endemic countries, and also in those who have been in close contact with immigrants from endemic countries.
Five patients with dacryocystorhinostomy failures were examined with computed tomography or computed tomographic dacryocystography. In computed tomographic dacryocystography, radiopaque dye was instilled into the lacrimal sac before computed tomography to show its shape, location, and relation to surrounding structures. Problems with the bony ostium were detected in all five patients. Recurrent nasal polyposis, a retained metallic clip, and an unresected ethmoid air cell were also identified. Computed tomography and computed tomographic dacryocystography provided important information that facilitated reoperation after dacryocystorhinostomy failure.
A comparison was made of the reliability and validity of two self-rating scales, the Children's Depression Inventory (CDI) and Depression Self-Rating Scale (DSRS), in the diagnosis of depression in 93 children (aged 8-16 years) attending a university child psychiatry department. The two scales were of comparable merit but had only moderate discrimination between depressed and non-depressed children, with each scale having a misclassification rate of 25%. Better agreement was obtained in more verbally intelligent children, irrespective of age. Girls scored higher on the instruments than boys. No significant relationship was found between teacher assessment of classroom behaviour and the two self-rating depression instruments.
Wooden foreign bodies in the orbit are not detectable by standard roentgenography. Reports in the literature on the ability of computed tomography (CT) to detect orbital wooden foreign bodies have varied. To evaluate whether magnetic resonance imaging (MRI) would offer any advantage over CT in detecting wood in the orbit. MRI and CT were performed on an in vitro model of wooden foreign bodies in the orbit. Woods of different types and sizes were studied in vegetable fat backgrounds chosen to simulate orbital fat. On CT, most types of wood were hypodense to fat. Appropriate window settings were critical in the detection of wood by CT: in this model, a window width of 1000 Hounsfield units was optimal. On MRI, all types of wood were hypointense to fat. Small pieces of wood were surrounded by an MRI truncation artifact consisting of hyperintense spots. T1-weighted images demonstrated wood better than T2-weighted images and required less scanning time than either proton density or T2-weighted images, MRI was superior to CT in detecting the smallest pieces of wood. The role of MRI in the detection of orbital wooden foreign bodies in clinical practice remains to be determined.
Karyotypes were examined in 512 (91.9%) of 557 male patients in an institution for the mentally handicapped. A total of 110 (21.5%) had an abnormal karyotype: 65 (12.7%) with Down's syndrome, 30 (5.9%) with the fragile X syndrome, 13 (2.5%) with autosomal anomalies other than Down's syndrome (12 unbalanced, one balanced), and two (0.4%) with sex chromosome anomalies.
Optic nerve dysfunction in thyroid eye disease is thought to be due to compression of the optic nerve by enlarged extraocular muscles near the orbital apex. High-resolution computed tomography (CT) scans of 78 orbits of 31 patients with thyroid eye disease were reviewed. Axial scans alone were inadequate for demonstrating compression of the optic nerve. With a coronal reformatted scan from the axial scans, a muscular index was devised and measured to reflect extraocular muscle impingement on the optic nerve. Orbits with optic nerve dysfunction had significantly higher muscular indices than those without optic nerve dysfunction, supporting the hypothesis that optic nerve dysfunction is usually secondary to compression by enlarged extraocular muscles. Muscular indices of 67% or greater in patients with optic nerve dysfunction were diagnostic of compressive optic neuropathy, while muscular indices of less than 50% appeared to exclude optic nerve compression. A single case of optic nerve dysfunction without muscular compression is also discussed.
Eighty-five patients were classified as having definite (n = 34), probable (n = 18), or possible (n = 33) multiple sclerosis using the criteria of Poser. Each patient had an enhanced computed tomographic examination, and most had cerebrospinal fluid and evoked response studies at the same time. Abnormalities including focal decreased brain density, abnormal enhancement, and cerebrospinal fluid space enlargement were found in 62% of patients (85% of those with definite, 39% of those with probable, and 52% of those with possible multiple sclerosis), and abnormal enhancing areas were demonstrated in 29% (44% of those with definite, 17% of those with probable, and 21% of those with possible disease). In the subgroup of patients with definite multiple sclerosis and recent clinical exacerbation (within the prior 8 weeks), abnormal enhancement was present in 89%. There was a strong correlation between clinical exacerbation and abnormal contrast enhancement. Cerebrospinal fluid studies (IgG, white blood cell count, total protein) had no correlation with exacerbation or abnormal enhancement. Maps of low-density and enhancing areas were similar to those previously described in postmortem studies. Computed tomography thus provides an in vivo, objective, and anatomically specific map of the brain parenchyma and the integrity of the blood-brain barrier that is useful in research studies evaluating the treatment of multiple sclerosis. It is also useful in patients in whom the diagnosis of multiple sclerosis is suspected but not certain on the basis of clinical and laboratory evaluation.
Brain computed tomographic scans of 60 patients with early-onset Alzheimer's disease (mean age, 60.7 years) were compared with those of age- and sex-matched control subjects. Computed tomographic analysis included standard ventricular measurements as well as subjective ratings of ventricular and sulcal size. These indices were correlated with the results of a battery of neuropsychological tests and electroencephalographic findings. Linear measurements of ventricular size were significantly greater in the patients with Alzheimer's disease than in the age-matched control group (p less than 0.0005). Using subjective appraisal of ventricular and sulcal size, the neuroradiologist noted abnormalities significantly more often in patients than in controls (p less than 0.0005). Linear measurements of ventricular size correlated significantly (p less than 0.05) with the severity of aphasia and dementia and the presence of electroencephalographic abnormalities. There was, however, no correlation between the subjective judgment of cortical atrophy and the degree of impairment as measured by neuropsychological tests. The findings in this study demonstrate the usefulness of computed tomographic imaging in Alzheimer's disease of early onset.
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To better understand the immunologic effects of lymphoid irradiation (LI), blood levels of T cell subsets were sequentially monitored in 15 patients before, during, and after irradiation treatment for Hodgkin's disease. Blood levels of all lymphocytes, T cells, and T cell subsets (defined by OKT4 and OKT8) fell dramatically and in similar proportions during early therapy, reaching levels less than 20 to 25% of control by the completion of mantle irradiation, and continuing at very depressed levels through the completion of therapy. Blood levels of OKT8-reactive (OKT8+) cells returned to pretreatment levels (402 +/- 38/mm3 vs 360 +/- 32/mm3 pretreatment) between 6 to 8 mo after LI, whereas blood levels of OKT4-reactive (OKT4+) cells returned to only 42% of previous values (242 +/- 22/mm3 vs 584 +/- 34/mm3 pretreatment) over the same period. The pre-LI ratio of OKT4+ to OKT8+ cells was 1.85 +/- 0.24 and fell to 0.65 +/- 0.05 between 6 to 8 mo after LI. During the recovery period, discrepancies of 208 +/- 32 cells/mm3 (3 to 5 months post LI) and 198 +/- 32 cells/mm3 (6 to 8 mo post LI) developed between the blood levels of OKT3+ cells and the sum of OKT4+ and OKT8+ cells. This suggests the emergence of OKT4+/OKT3-, OKT8+/OKT3-, and/or OKT4+/OKT8+ cells. In five patients, the sum of OKT4+ and OKT8+ cells was compared with the number of cells simultaneously co-stained by OKT4 and OKT8. It appeared that a significant proportion of the cells were OKT4+/OKT3- and OKT8+/OKT3- lymphocytes. We concluded that LI is similarly cytotoxic to peripheral blood T cell subpopulations. The reversed ratio after LI is a result of a slower repopulation of the peripheral blood by OKT4+ cells relative to OKT8+ cells. T cells after LI show a high degree of antigenic immaturity. It is postulated that the bone marrow that lies outside the fields of treatment and contains predominantly immature OKT8+/OKT3- cells is a major source of T cells repopulating the peripheral blood after LI.
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The kinetics of oxygen consumption and (Na+,K+)-ATPase-mediated K+ transport was examined by reintroducing K+ into a K+-depleted suspension of renal tubules. In the presence of the substrates glucose, lactate, and alanine, a K+/O2 ratio of 10.4 +/- 0.2 was obtained, and the apparent K1/2 for K+ transport with respect to external K+ concentration was 0.9 mM. Supplementation of the substrates with the short chain fatty acid, butyric, had a 3-fold effect on the kinetic parameters examined: 1) the quantity of (Na+,K+)-ATPase-mediated ion transport per oxygen consumed fell by 17 +/- 2%; 2) the maximum rate of K+ transport increased by nearly 50%; and 3) the apparent K1/2 for transport with respect to external K+ concentration rose to 1.5 mM. These results indicate that despite decreasing the quantity of ATP produced per oxygen consumed, short chain fatty acids are able to increase the overall production of ATP during periods of high metabolic demand. The coupling between the two major metabolic processes of the renal cell, (Na+,K+)-ATPase-mediated ion transport and mitochondrial oxidative phosphorylation, is addressed in the context of these findings.
Cellular oxygen consumption was monitored during stimulation and inhibition of the Na+- and K+-dependent adenosine triphosphatase in a suspension of intact tubules isolated from the rabbit renal cortex. Respiratory rates were compared to the ADP-stimulated respiratory rate (state 3 rate) obtained in mitochondria released directly from the renal tubules by digitonin shock. At 37 degrees C, in the presence of NADH-linked substrates and fats, isolated renal cells respire at 50 to 60% of the state 3 rate. Inhibition of the (Na+,K+)-ATPase with the cardiac glycoside, ouabain, results in a decline in respiration to 25 to 30% of the state 3 rate. Stimulation of the (Na+,K+)-ATPase produced as a result of nystatin-mediated dissipation of plasma membrane Na+ and K+ gradients results in increased respiration with an oxygen consumption rate characteristic of optimal ATP synthesis (state 3). The relationship between metabolic substrate regimen, mitochondrial respiratory capacity, and cellular energy demand is examined in the context of these findings.
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Explore the source record for details and available documents.