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Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 937 records · Page 52Linked to original sources
PubMed1984

Lesions of the putamen and dystonia: CT and magnetic resonance imaging.

We studied posthemiplegic hemidystonia in an adult, and generalized dystonia in two children. CT and magnetic resonance imaging (MRI) studies in the adult revealed infarction of the contralateral putamen and, to a much lesser extent, the head of the caudate nucleus. Both children had subacute encephalopathies (possible Leigh's disease), and CT revealed bilateral putamen lesions when generalized dystonia was the predominant clinical disorder. These cases and other reports of symptomatic dystonia suggest that lesions of the putamen correlate with dystonia.

Brain Diseases↗
PubMed1983

Adrenal and sex steroid hormone production by a virilizing adrenal adenoma and its diagnosis with computerized tomography.

The presence of an androgen-secreting tumor in a 29-year-old woman was confirmed and its location was determined by computerized axial tomographic (CAT) scanning. The hormone production from this virilizing adrenal adenoma was studied in vivo and in vitro. The major secretory products of the tumor (as compared to normal adrenal tissue) were testosterone (24-fold) and 17 beta-estradiol (five-fold). Although the adenoma produced lesser amounts of dehydroepiandrosterone sulfate (DHEAS), the demonstration of elevated serum testosterone and DHEAS in serial samples was a better marker for an androgen-secreting adrenal tumor than were the urinary 17-ketosteroids, which remained in the upper limit of normal. The hormone production from the tumor depended neither on adrenocorticotropic hormone nor on human chorionic gonadotropin. The conclusions were that: (1) on the basis of serial measurements of serum testosterone and DHEAS, virilizing adrenal adenomas may be suspected when the concentrations of these hormones reach or exceed 200 ng/dl and 6,600 ng/ml, respectively; (2) the high-resolution CAT scanner can accurately localize these tumors; (3) cosmetic and menstrual dysfunction regressed after resection of the tumor; and (4) virilizing adrenal adenomas may produce both androgens and estrogens.

17-Ketosteroids↗
PubMed1983

Cell survival kinetics in peripheral blood and bone marrow during total body irradiation for marrow transplantation.

Cell survival kinetics in both peripheral blood and in bone marrow have been studied over the time course of hyperfractionated total body irradiation (TBI) for bone marrow transplantation. Our unique TBI regimen allows the study of the in vivo radiation effect uncomplicated by prior cyclophosphamide, since this agent is given after TBI in our cytoreduction scheme. Peripheral blood cell concentrations were monitored with conventional laboratory cell counts and differentials. Absolute bone marrow cell concentrations were monitored by measuring cell concentrations in an aspirate sample and correcting for dilution with blood by a cell cycle kinetic method using cytofluorometry. In the entire group of patients, time to engraftment with donor marrow was found to be 16.6 +/- 4.4 days and more rapid when a nucleated donor cell dose of greater than or equal to 4.0 X 10(8) cells/kg was given. For lymphocytes in peripheral blood in patients in remission, the effective D0 ranged from 373 rad in 10 children less than or equal to 10 y old, to 536 rad in the four patients between 11-17 y old, while n = 1.0 in all groups. There was no trend observed according to age. Granulocytes had a much higher effective D0, approximately 1000 rad in vivo. Absolute nucleated cell concentration in marrow dropped slowly initially, due to an increased lymphocyte concentration in marrow during a concurrent drop in lymphocyte concentration in peripheral blood, but eventually fell on the last day of TBI ranging from 7-44% of the initial marrow nucleated cell concentration. Marrow myeloid elements, however, dropped continuously throughout the course of TBI.

Adolescent↗
PubMed1981

CT of sacroiliac joints in secondary hyperparathyroidism.

Computed tomography (CT) was used to evaluate the sacroiliac (SI) joints in 12 patients with secondary hyperparathyroidism. The CT scan was superior to conventional radiography in all patients, and correlated well with previous reports of SI abnormalities in chronic renal failure.

Adult↗
PubMed1980

Accuracy of common hapatic duct size in the evaluation of extrahepatic biliary obstruction.

High-resolution real-time ultrasound sector scanning is helpful in showing the normal common hepatic duct. The authors evaluated the accuracy of using a 4-mm internal diameter as the upper limit of normal in evaluation of obstruction. Of 98 patients with jaundice or right-upper-quadrant pain whose duct exceeded 4 mm, obstruction was proved in 84. Fourteen patients had no radiographic or pathological evidence of obstruction, but 7 had undergone cholecystectomy and clinical evidence suggested another 6 had passed a stone before or after the ultrasound study. Of 72 patients with a duct greater than or equal to 4 mm, only one had obstruction; a mass blocked the right and left hepatic ducts. The sensitivity of the test is 99%, the specificity 87%. Thus if the common hepatic duct is more than 4 mm in internal diameter on ultrasound, extrahepatic biliary obstruction is probably present.

Cholestasis, Extrahepatic↗
PubMed1980

The discrepancy between radiographic and sonographic bile-duct measurements.

The upper limit of the normal bile-duct diameter is significantly smaller by ultrasound than that generally accepted for radiographic techniques. This appears to be due to (a) radiographic magnification, (b) ultrasonic underestimation, (c) a possible choleretic effect of radiographic contrast material, and (d) the fact that different regions are measured with different techniques. The diameter of the common hepatic duct was measured by ultrasound in 30 patients prior to and during intravenous cholangiography, and these measurements were correlated with each other and with the radiographic measurement. In vitro studies were also performed. It was found that the choleretic effect significantly increased duct size in a small percentage of cases. The radiographic magnification was a factor of 1.3, and the ultrasonic diameter was about 1.5-2.0 mm too small. Perhaps the most important cause of the discrepancy was measurement of different regions with different techniques.

Cholangiography↗
PubMed1980

Anterior displacement of kidneys by fat.

Computed tomography has demonstrated, in a patient with a large amount of retroperitoneal fat, that the kidneys may lie farther anteriorly than previously reported.

Adipose Tissue↗
PubMed1976

Immunogenetic polymorphism of lipoproteins in swine. 1. Four additional serum beta-lipoprotein allotypes (Lpp2, Lpp4, Lpp5 and Lpp15) in the Lpp system.

Four additional swine serum lipoprotein allotypes are described. Specific anti-allotype reagents were obtained from alloimmune precipitating sera produced in lipoprotein-defined-type recipients immunized with normal sera and subsequently with lipoprotein fractions. Identification studies indicate that the four serologically defined low-density lipoprotein (LDL) variants, designated Lpp2, Lpp4, Lpp5 and Lpp15, are members of a previously described Lpp system. The individual specificities, Lpp2, Lpp4 and Lpp5, are determined by three co-dominant autosomal genes, Lpp2, Lpp4 and Lpp5, respectively, whereas the common specificity, Lpp15, is controlled by a complex of genetic information of the Lpp2 and Lpp4 genes, and by the two previously described alleles, Lpp1 and Lpp3; Lpp15 occurs on the same molecule with respective individual specificity. The Lpp5 and Lpp15 antigens behave as a pair of alternative allotypic specificities. The double immunodiffusion test in agar was employed to demonstrate independent phenotypic expression of each allelic gene in the Lpp heterozygous animals, for the analysis of the immune sera, and for lipoprotein testing of 3305 sera. Marked differences in gene frequencies were found between the swine breeds tested. As a result of characteristic frequencies, only nine of 15 possible Lpp genotypes were found in the breeding herds tested; the remaining six genotypes were obtained from testcross matings.

Alleles↗
PubMedDate not supplied

Simulated dipeptide recognition by vancomycin.

The antimicrobial activity of vancomycin and related glycopeptide antibiotics is due to stereospecific recognition of polypeptide components in bacterial cell walls. To better understand how these antibiotics recognize polypeptide determinants, we have developed dynamic models of the complexes formed by the vancomycin aglycon and two different dipeptide ligands, Ac-D-ala-D-ala and Ac-D-ala-gly. Molecular dynamics simulations of the two complexes, initially conditioned with distance constraints derived from two-dimensional nuclear magnetic resonance (NMR) studies, are conformationally stable and propagate in a manner consistent with the NMR-derived constraints after the constraints are removed. Free energy calculations accurately predict the relative binding affinity of these two complexes and help validate the simulation models for detailed structural analysis. Although the two ligands adopt similar conformations when bound to the antibiotic, there are clear differences in the configuration of intermolecular hydrogen bonds, the overall shape of the antibiotic, and other structural features of the two complexes. This analysis illustrates how complex structural and dynamic factors interrelate and contribute to differences in binding affinity.

Anti-Bacterial Agents↗
PubMedDate not supplied

Image-directed and color Doppler studies of gallbladder tumors.

Thirteen cases of primary adenocarcinoma of the gallbladder (GB), 1 of malignant fibrous histocytoma, 3 of metastatic adenocarcinoma, 5 of adenoma, 5 of polypus, 2 of xanthogranuloma, 6 of chronic cholecystitis, 4 of acute cholecystitis, and 8 of subacute cholecystitis were studied by image-directed and color Doppler ultrasonography (CDUS). All of the 14 cases of primary GB cancer (10 masses, 4 thickening wall) were found to have a high velocity arterial blood flow signal in the wall of the GB. In contrast, the 3 cases of metastatic cancer of the GB had no blood flow signal in the wall of the GB. For the 30 cases of benign lesions of the GB, only in 12 cases was a low velocity blood flow signal found. Nine of 10 cases of primary GB malignancy were found to have high velocity arterial blood flow signals in the tumor masses. No blood flow signal was observed in the masses of 13 cases (3 of metastatic adenocarcinoma, 5 of adenoma, 5 of polypus). An abnormal high velocity arterial blood flow signal observed within masses in the GB or in the GB wall is a significant feature of primary GB cancer and thus helps to differentiate primary GB cancer from metastatic and benign lesions of the GB.

Adult↗