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Biomedical subjects

B C Lee

Publications and source records attributed to B C Lee.

At least 163 records · Page 9Linked to original sources

Penetrating extremity trauma: identification of patients at high-risk requiring arteriography.

Indications for arteriography in patients with penetrating trauma to the extremities remain controversial. Some clinicians have recommended universal use of arteriography, whereas others prefer to rely on physical findings alone. To better define our indications for contrast studies, we reviewed clinical data on 306 patients (349 extremities) with penetrating trauma who were admitted during a prior 2-year period (1985 to 1987). Injuries were caused by stab wounds in 50 (14.3%) extremities and by gunshot wounds in 299 (85.7%) extremities. Twenty-seven of the 50 stab wounds (54%) required urgent exploration based on physical findings, whereas 23 underwent arteriography. None of these studies showed unsuspected arterial injury. Twenty-nine of 299 gunshot wounds (9.7%) underwent mandatory exploration, and arteriograms were performed on 270 extremities; findings in 30 studies (11.1%) were positive for unsuspected arterial injuries. Gunshot wounds were categorized according to location and number of arteriograms with positive results. Arteriograms of lateral thigh and upper arm injuries resulted in no positive outcomes. Positive study results were recorded in 22.9% of calf injuries, 20% of forearm and antecubital injuries, 9.5% of popliteal fossa injuries, 9.0% of medial and posterior thigh injuries, and 8.3% of medial and posterior upper arm injuries. We recommend arteriography for penetrating injuries to these high-risk areas. However, clinical evaluation alone is accurate for identification of arterial trauma with lateral thigh or upper arm wounds and stab wounds to the extremities.

Adolescent↗

Metaplastic pancreatic cells in liver tumors induced by diethylnitrosamine.

Metaplastic pancreatic cells have been infrequently observed in fish liver tumors induced by chemical carcinogens. An investigation with nitrosamine-exposed trout was undertaken to characterize the relationships of metaplastic pancreatic cells with other cell types. Eight-week-old rainbow trout (Salmo gairdneri) were fed a control diet or diets containing 500 ppm beta-naphthoflavone (BNF), 2000 ppm indole-3-carbinol (13C), or 100 ppm Aroclor 1254 (PCB) for 6 weeks. The fish were then exposed to 250 ppm diethylnitrosamine for 24 hr in an aqueous aquarium bath and reared on control diet for 39 weeks postexposure. Livers were excised, processed to paraffin sections, and stained with hematoxylin and eosin for histological evaluation. Metaplastic pancreatic cells were found only in tumors. Of the tumors with metaplastic pancreatic cells, 100/105 (95.2%) contained neoplastic cholangiolar components. Only 5/105 (4.76%) were hepatocellular carcinomas. 13C pretreatment inhibited the incidence of cholangiolar tumors (cholangioma 3.6% vs 31.3%, cholangiocarcinoma 3.6% vs 13.0%) and metaplastic pancreatic cells (5.1% vs 19.1%), whereas BNF and PCB had no effect. A hepatocellular origin for metaplastic pancreatic cells is supported. Cholangiolar neoplasia is associated with the expression, growth, or survival of metaplastic pancreatic cells in liver tumors. Hepatocarcinogenicity should not be described entirely by hepatocellular events since cholangiolar and metaplastic pancreatic cells can respond associatively to carcinogens and dietary modulators.

Adenoma, Bile Duct↗

Computed tomography versus magnetic resonance imaging of the brain. A collaborative interinstitutional study.

A retrospective study (1983-1984) of magnetic resonance imaging (MRI) and computed tomography (CT) examinations in 471 patients with known pathology in the brain and craniocervical junction was conducted in order to determine the relative efficacy of MRI versus CT. All MRI examinations involved slice thickness greater than 10 mm, and only single-slice single-echo or multislice single-echo imaging techniques were available. These studies were evaluated independently by two neuroradiologists from a panel of six for anatomic abnormalities, lesion contrast, and radiologist's impression. Results, which excluded microadenomas of the pituitary and approximately 9% of studies in which consensus was not achieved by the readers, were as follows: (1) 14% of the studies were positive on MRI but normal on CT; (2) in 55% of the studies, MRI was better than CT; (3) MRI was equal or better than CT in 95% of the studies; and (4) CT was better than MRI in 5% (21/421) of the examinations. There were no patients in this series where CT was positive but MRI missed the abnormality.

Adult↗

Identification and comparative analysis of the lactoferrin and transferrin receptors among clinical isolates of gonococci.

Neisseria gonorrhoeae expresses receptors for both lactoferrin (LF) and transferrin (TF). To determine whether qualitative or quantitative changes in these receptors, or both, correlate with the pattern of disease due to N. gonorrhoeae, a dot binding assay with whole cells was used to measure the absolute receptor levels expressed during iron-limited growth of strains isolated from asymptomatic patients and patients with urethritis, cervicitis, pelvic inflammatory disease and disseminated infection. Lactoferrin and transferrin receptor complexes were purified by affinity chromatography and their protein profiles were compared. The molecular weights of the LF and TF receptor complexes from a representative sample of gonococci were homogeneous. We conclude that there is no relationship between the LF and TF receptor levels and disease manifestation, auxotype or serotype.

Carrier State↗

Penicillin-binding proteins of Haemophilus ducreyi.

The penicillin-binding protein (PBP) profile of Haemophilus ducreyi was determined by a whole-cell-labeling assay. Only two major PBPs, of molecular weights 90,000 (PBP 1) and 38,500 (PBP 2), were detected in six of eight strains studied. Competition binding experiments and the attendant morphological effects suggested that PBP 1 was either a functional amalgamation or a lack of resolution of two proteins equivalent to PBPs 1 and 3 of Escherichia coli.

Anti-Bacterial Agents↗

Comparative analysis of the transferrin and lactoferrin binding proteins in the family Neisseriaceae.

Intact cells of several bacterial species were tested for their ability to bind human transferrin and lactoferrin by a solid-phase binding assay using horseradish peroxidase conjugated transferrin and lactoferrin. The ability to bind lactoferrin was detected in all isolates of Neisseria and Branhamella catarrhalis but not in isolates of Escherichia coli or Pseudomonas aeruginosa. Transferrin-binding activity was similarly detected in most isolates of Neisseria and Branhamella but not in E. coli or P. aeruginosa. The expression of transferrin- and lactoferrin-binding activity was induced by addition of ethylenediamine di-o-phenylacetic acid and reversed by excess FeCl3, indicating regulation by the level of available iron in the medium. The transferrin receptor was specific for human transferrin and the lactoferrin receptor had a high degree of specificity for human lactoferrin in all species tested. The transferrin- and lactoferrin-binding proteins were identified after affinity isolation using biotinylated human transferrin or lactoferrin and streptavidin-agarose. The lactoferrin-binding protein was identified as a 105-kilodalton protein in all species tested. Affinity isolation with biotinylated transferrin yielded two or more proteins in all species tested. A high molecular mass protein was observed in all isolates, and was of similar size (approximately 98 kilodaltons) in all species of Neisseria but was larger (105 kilodaltons) in B. catarrhalis.

Escherichia coli↗

Iron resistance of hepatic lesions and nephroblastoma in rainbow trout (Salmo gairdneri) exposed to MNNG.

Histochemical markers are important for the early detection of chemically initiated neoplasia in experimental animal studies. The marker, iron resistance, was evaluated in the Shasta strain of rainbow trout (Salmo gairdneri). Twenty-one-day-old trout embryos were exposed to 100 ppm aqueous N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 30 min in a static water bath. Fish were fed a semipurified diet, and sampled monthly from the 4th to the 9th month. Two days before sampling, fish were iron-loaded with a single ip dose of 0.30 mg iron dextran/100 g body weight. Livers and kidneys were conventionally processed to paraffin sections for iron, or hematoxylin and eosin (H&E) staining. Normal hepatocytes accumulated iron in pericanalicular locations, but in hepatocytes from carcinogen-altered foci and tumors, iron staining was clearly reduced or absent. Normal renal tubule cells exhibited slight to moderate iron staining, while those from nephroblastoma were iron resistant. These results establish iron resistance as a property of preneoplastic and neoplastic trout hepatocytes and nephroblastoma cells for the first time. Iron resistance may offer a practical histochemical marker in experimental fish models of hepatocellular carcinoma and nephroblastoma.

Adenoma↗

31P spectroscopy in thrombolytic treatment of experimental cerebral infarct.

Ischemic changes produced by autogenous clot embolization of intracranial arteries were monitored by continuous surface-coil 31P spectroscopy in 12 rabbits: six were used as controls and six were treated intravenously with tissue-type plasminogen activator. The animals were sacrificed and the brains were fixed with intravital stains. The results indicate that spectral changes are reversible only when thrombolysis therapy is started within 30 min after ischemic changes are detected. The improvement of the 31P spectrum correlated with postmortem changes.

Animals↗

Congenital and perinatal lesions.

Most congenital abnormalities can be traced to defects occurring at a specific stage during embryologic development. Anatomic deformities of the ventricular system and brain surface are visualized and myelination of the white matter is well evaluated on MR scans so that congenital abnormalities may be differentiated from perinatal lesions. MR imaging is often the only imaging modality required for complete assessment of abnormalities in the neonatal period.

Brain↗

Congenital cerebrospinal fluid-containing intracranial abnormalities: a sonographic classification.

Ultrasound is useful as a primary modality for diagnosis of complex nonhydrocephalic intracranial malformations. We present 10 cases of intracranial cerebrospinal fluid containing abnormalities that may be diagnosed by ultrasound. Congenital abnormalities presented include holoprosencephaly, hydranencephaly, agenesis of the corpus callosum with interhemispheric cyst, porencephaly, schizencephaly, and arachnoid cyst. Ultrasound may be used in the fetus or neonate in detecting and separating these abnormalities from hydrocephalus.

Abnormalities, Multiple↗

Modulation of diethylnitrosamine-induced hepatocarcinogenesis and O6-ethylguanine formation in rainbow trout by indole-3-carbinol, beta-naphthoflavone, and Aroclor 1254.

Rainbow trout were fed a diet containing indole-3-carbinol (2000 ppm), beta-naphthoflavone (500 ppm), or Aroclor 1254 (100 ppm) for 6 weeks before a single 24-hr exposure to an aqueous solution of 250 ppm diethylnitrosamine (DEN). The fish were killed 42 weeks later to determine the carcinogenic response. DEN exposure produced an 80.2% incidence of liver tumors and an average of 3.47 tumors per tumor-bearing fish, whereas no tumors were detected in the sham-treated control fish. Tumor induction was inhibited by indole-3-carbinol (27.5% incidence, 1.89 tumors per tumor-bearing fish) but enhanced by beta-naphthoflavone (91.8% incidence, 3.60 tumors per tumor-bearing fish). Aroclor 1254 had no effect on DEN-induced hepatocarcinogenesis (80.0% incidence, 3.03 tumors per tumor-bearing fish). The effects of these modulators on O6-ethylguanine and 7-ethylguanine formation (measured by HPLC and fluorescence spectrophotometry) were examined. Liver DNA ethylguanine levels were reduced in indole-3-carbinol-pretreated fish and increased in beta-naphthoflavone-pretreated fish compared to untreated controls after DEN exposure. Aroclor 1254 pretreatment had no significant effect on DNA ethylguanine formation. Similar O6-ethylguanine to 7-ethylguanine ratios were found among the control and treated groups. The results of this study indicate that modulation of DEN hepatocarcinogenesis by indole-3-carbinol and beta-naphthoflavone may be mediated by their effects on O6-ethylguanine formation and, therefore, on the initiation phase of carcinogenesis.

Animals↗

Specificity of the lactoferrin and transferrin receptors in Neisseria gonorrhoeae.

Lactoferrin (LF) and transferrin (TF) are postulated to be important physiological sources of iron for Neisseria gonorrhoeae. A dot binding assay involving the use of gonococcal total membranes derived from cells grown in iron-limited conditions demonstrated the presence of separate receptors for LF and TF. The ligand and functional specificities of these receptors were examined in competition-binding and growth experiments. The results indicate that the LF and TF receptors are highly specific for the human protein, suggesting that this property may be partially responsible for conferring the human host specificity of N. gonorrhoeae.

Animals↗

No sex-related differences in human corpus callosum based on magnetic resonance imagery.

Recent studies have reported sex-related differences in the morphology of the human corpus callosum in cadaver brains. To further investigate these reports, sagittal magnetic resonance image scans from 40 male and 40 female subjects were used to compare callosal morphology. Relative callosal measurements were calculated by morphometric analysis. Significant sex-related differences were not found for callosal areas, maximal callosal width, or callosal curvature. These results indicate the need for further study before claims of sex-related differences can be accepted.

Corpus Callosum↗

Magnetic resonance imaging of peri-aqueductal lesions.

Fourteen lesions in the peri-aqueductal region were evaluated by 0.5T magnetic resonance imaging (MRI) and computed tomography (CT). Fifty normal magnetic resonance studies of the same region were reviewed. The aqueduct of Sylvius is seen in the midline sagittal MRI sections in all normal patients. It is not usually visible in cases of benign stenosis but may be seen in membranous obstruction. Benign stenosis is distinguished from neoplastic obstruction by the lack of increased signal on T2 weighted techniques. Blood within pineal tumours is easily detected and may be differentiated from lipomas, cystic lesions and solid tumours of the brain stem. Arachnoid cysts are also visible in MRI scans.

Arachnoid↗

Dural and carotid cavernous sinus fistulas. Diagnosis, management, and complications.

Carotid cavernous sinus fistulas (CCSFs) are a rare entity occurring as a result of head trauma and also spontaneously. The major threat from these fistulas is loss of vision. The authors reviewed 18 cases of direct and dural CCSFs seen over the last 10 years and compared our results with 553 cases treated in the literature. Seventy-one percent of our patients with direct CCSFs had successful balloon embolization. In the literature, successful closure of direct CCSFs has ranged from 58 to 100%. As experience with embolization techniques broadens, morbidity and mortality is reduced. The clinical features, diagnostic procedures, therapeutic options, and complications of treatment of CCSFs are discussed.

Adolescent↗

Occurrence of an unusual amount of an odd-numbered fatty acid in glycosphingolipids from human cataracts.

Human cataractous glycosphingolipids were isolated and purified according to previously established procedures. Fatty acid analyses of the purified glycosphingolipid revealed the presence of a significant amount of an odd-chain fatty acid. This was confirmed by methane (CH4) chemical ionization mass spectrometry, which showed characteristic ions at m/z 397, 425, 437, and 365. These ions facilitated the determination of molecular weight and the assignment of C25:0 (n-pentacosanoic acid) to this fatty acid in question. This may be the first time that such an unusual distribution of a single odd-chain fatty acid has been shown to occur in glycosphingolipid from any tissue.

Brain↗

The diversity of neurologic events in systemic lupus erythematosus. Prospective clinical and computed tomographic classification of 82 events in 71 patients.

To investigate outcome and pathophysiology of central nervous system (CNS) systemic lupus erythematosus (SLE), we prospectively codified all cases of CNS SLE. Eighty-two events occurred in 71 patients. Four events in four patients were due to infection and were excluded. Twelve events occurred in 11 women with positive antinuclear antibody but negative anti-DNA antibody test reactions and no other manifestation of SLE. Of the remaining 66 events (56 patients), 26 events were "isolated" and 40 "complex." Non-CNS SLE was "active" during 47 events and "inactive" during 19 events. "Isolated" CNS events were equally likely in clinically "active" and "inactive" SLE. Patients with active SLE were as likely to have an episodic or remittent course as were patients with inactive SLE. "Complex" events, however, were more likely to have favorable outcome than were "isolated" events. "Isolated" events without focal CT abnormalities, the only component of CNS SLE that can be called diffuse lupus encephalitis, accounted for only 20% of all neurologic events.

Adolescent↗