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Biomedical subjects

C Lee

Publications and source records attributed to C Lee.

At least 847 records · Page 47Linked to original sources
PubMed1988

Multicentric papillary adenocarcinoma of the renal pelvis and ureter. Report of a case with ultrastructural study.

A case of multicentric papillary adenocarcinoma arising in the renal pelvis and proximal ureteral mucosa of a 35-year-old man is presented. The left nephrectomy specimen demonstrated multiple, fungating, papillary tumors. The largest tumor measured 10 X 9 X 6 cm and invaded the renal parenchyma. Smaller tumors with long stalks were found. Microscopically, the papillary fronds of each neoplasm were lined by a single layer of cuboidal to low columnar epithelium admixed with a few areas of invasive tubular adenocarcinoma. The adjacent pelvic mucosa was the site of cuboidal epithelial metaplasia. The ultrastructure of both the papillary tumor and the pelvic mucosa suggested that they originated from the nonmucigenic metaplastic epithelium with a partial similarity to the lining of the proximal convoluted tubule. The growth pattern and the multicentric development of this unusual neoplasm suggest that this is a case of the malignant counterpart of the nephrogenic adenoma in the kidney and ureter, and reflect a biologic behavior corresponding to ordinary urothelial papillary tumors.

Adenocarcinoma, Papillary↗
PubMed1988

Dynamic behavior of endoplasmic reticulum in living cells.

Endoplasmic reticulum (ER) was studied by fluorescence microscopy of living CV-1 cells treated with the fluorescent carbocyanine dye DiOC6(3). Using video recording and image processing techniques, several distinct forms of highly localized movements of ER were documented, categorized, and analyzed in terms of mechanism and structural implications. These include tubule branching, ring closure, and sliding. These localized movements have been observed to generate the basic elements of ER: linear tubules, polygonal reticulum, and triple junctions. We propose that as such they act as the mechanism for constructing the polygonal lattice of interconnected membrane tubules that constitutes ER. The nature of these movements suggests possible involvement of the cytoskeleton, and, in view of the close correlations in the distributions of ER and microtubules, and the accompanying paper (Dabora and Sheetz), it is possible that microtubules may play a role in generating ER motility and in constructing and maintaining the ER network in living cells.

Animals↗
PubMed1988

Population coding of saccadic eye movements by neurons in the superior colliculus.

The deeper layers of the superior colliculus are involved in the initiation and execution of saccadic (high velocity) eye movements. A large population of coarsely tuned collicular neurons is active before each saccade. The mechanisms by which the signals that precisely control the direction and amplitude of a saccade are extracted from the activity of the population are unknown. It has been assumed that the exact trajectory of a saccade is determined by the activity of the entire population and that information is not extracted from only the most active cells in the population at a subsequent stage of neural processing. The trajectory of a saccade could be based on vector summation of the movement tendencies provided by each member of the population of active neurons or be determined by a weighted average of the vector contributions of each neuron in the active population. Here we present the results of experiments in which a small subset of the active population was reversibly deactivated with lidocaine. These results are consistent with the predictions of the latter population-averaging hypothesis and support the general idea that the direction, amplitude and velocity of saccadic eye movements are based on the responses of the entire population of cells active before a saccadic eye movement.

Animals↗
PubMed1988

The effects of brain bilirubin deposition on auditory brain stem evoked responses in rats.

Auditory brain stem evoked responses (ABR) in newborn infants are altered by elevated serum bilirubin levels and may be used as an indicator of bilirubin toxicity. The hypothesis of our study was that hyperbilirubinemia may affect ABR's because of bilirubin deposition in the brain stem. We examined this hypothesis by studying 21 male adult rats divided into three groups: group A, control (n = 8); group B, low bilirubin (n = 6); and group C, high bilirubin (n = 7). Each experimental group was studied over 150 min. The control group received a buffer solution. The low bilirubin group received a low dose bilirubin bolus of 50 mg/kg followed by continuous infusion of 20 mg/kg/h. The high bilirubin group received a bolus of 100 mg/kg bilirubin followed by continuous infusion of 40 mg/kg/h. All groups received sulfisoxazole (50 mg/kg X 3) during the second hour of the study. Auditory evoked potentials were recorded at 0 and 150 min. At the end of the study, the brains were analyzed for bilirubin content. Bilirubin deposition in the 3 groups was 0.6 +/- 0.28 micrograms/g, 0.93 +/- 0.07 micrograms/g and 3.2 +/- 2.2 micrograms/g for the control, low bilirubin and high bilirubin groups, respectively. Bilirubin deposition in the brain was associated with a significant amplitude reduction of Wave I and III, but had no effect on absolute latencies and interpeak latencies. Very high brain bilirubin concentrations were associated with absence of Waves I and IV. Wave I was also significantly reduced in the low bilirubin group where there was slightly increased bilirubin deposition in the brain. We conclude that ABR changes in the form of wave amplitude reduction were associated with brain stem and cerebellum bilirubin deposition. We speculate that previously reported observations of abnormal ABR changes in hyperbilirubinemic newborn infants are associated with bilirubin deposition.

Animals↗
PubMed1988

Spinal fractures in blunt chest trauma.

In a series of 100 consecutive patients with mediastinal hemorrhage following blunt chest trauma, fractures and dislocations of the lower cervical, thoracic, and upper lumbar spine were causative of the mediastinal hemorrhage in nine patients. Spinal injury was clinically suspected in seven patients because of quadriplegia or paraplegia. However, in the two patients who were neurologically intact a spinal injury was not clinically suspected. In the initial triage of a patient with blunt chest trauma, the supine chest radiograph can play a key role in the identification of a potentially unstable spinal injury and the prevention of subsequent spinal cord injury.

Adult↗
PubMed1988

Intrathoracic lymphadenopathy in postprimary tuberculosis.

In the past, hilar or mediastinal lymphadenopathy was considered by many to be a feature of only the primary or first infection with Mycobacterium tuberculosis, and to exclude the diagnosis of reactivation or postprimary tuberculosis. In a series of 56 adult patients with documented postprimary disease due to M tuberculosis, we found hilar or mediastinal lymphadenopathy in three cases (5%). Although intrathoracic lymphadenopathy was more common in primary tuberculosis, we do not believe that intrathoracic lymphadenopathy is as specific for primary tuberculosis, particularly in the adult, as was once thought. For this reason, we believe that the roentgenographic demonstration of intrathoracic lymphadenopathy should not be used as a definitive research or clinical criterion for primary tuberculosis in an adult.

Adolescent↗
PubMed1988

Theories of family adaptability: toward a synthesis of Olson's Circumplex and the Beavers systems models.

Two typologies of family process, Olson's Circumplex Model and the Beavers Systems Model, are discussed, focusing particularly upon their definitions of family adaptability. It is argued that the two typologies are not simply "separate but equal" (11), but, rather, that there is an ambiguity in the Circumplex Model that disguises a fundamental theoretical overlap between the two. Olson's definition of adaptability is founded upon the concepts of morphogenesis and change; Beavers builds upon the concepts of negentropy and competence. It may be shown, however, that both understandings are necessitated by the theoretical writings of Olson and his colleagues. The nature of this ambiguity in the Circumplex Model is critically explored, and a higher-order model that attempts to synthesize these two theories is proposed.

Adaptation, Psychological↗
PubMed1988

Cerebellar hemangioblastoma symptomatic during pregnancy.

An 18-year-old woman presented during the 2nd month of her pregnancy with noncommunicating hydrocephalus due to a cerebellar hemangioblastoma. The tumor rapidly enlarged over a 12-day period after ventriculoperitoneal shunting, probably because of expansion of the vascular compartment. Serial computed tomography and magnetic resonance imaging observations support previous speculations in the literature that vascular engorgement of hemangioblastomas probably accounts for the rapid deterioration of some patients during pregnancy.

Adolescent↗
PubMed1988

Microcomputer-based image analysis systems for two-dimensional electrophoresis gels.

The intent of this overview is to provide the readers, especially those who are currently conducting two-dimentional electrophoresis, a basic understanding in the construction and use of microcomputer-based systems for the analysis of protein profiles generated by two-dimensional gel electrophoresis. In addition, a microcomputer-based system, employing fixed-point operations and effective algorithms, has been evaluated. The validity of this system has been demonstrated by using the two-dimensional silver-stained gels and fluorograms derived from the rat prostate. It is concluded that the present system can be used to aid the analysis of two-dimensional electrophoresis gels. An overall consideration of hardware and software components of a computer-based system is briefly discussed.

Computer Systems↗
PubMed1987

Eukaryotic initiation factor 4D, the hypusine-containing protein, is conserved among eukaryotes.

When mammalian cells are grown in medium containing [3H]spermidine, a single major tritiated protein identical to eukaryotic initiation factor 4D becomes labeled. This protein contains 1 residue/molecule of tritiated hypusine (N epsilon-(4-amino-2-hydroxybutyl)lysine), a rare amino acid which has been found in no other protein. In order to investigate the conservation of this protein, we examined two nonmammalian eukaryotes, the yeast Saccharomyces cerevisiae and the insect Drosophila melanogaster, and the eubacterial prokaryote Escherichia coli for the presence of the hypusine-containing protein. When the eukaryotic cells were grown in the presence of [3H]spermidine, electrophoretic analysis revealed a single labeled protein. In each case, the apparent molecular weight was near 18,000 and the relative pI was approximately 5.2, similar to the hypusine-containing protein of mammals. Amino acid analysis confirmed the presence of tritiated hypusine in each case, and silver staining of two-dimensional polyacrylamide gels demonstrated that, in yeast and fruit flies as in mammals, the protein is relatively abundant. In the eubacterium E. coli, one tritiated protein was predominant, but its molecular weight was 24,000 and we found no evidence that it contained tritiated hypusine. We found no evidence for the existence of the hypusine-containing protein in the archaebacterium Methanococcus voltae. These data suggest that the hypusine-containing protein is conserved among eukaryotes.

Amino Acids↗
PubMed1987

Phosphorothioate analogues of 2',5'-oligoadenylate. Enzymatic synthesis, properties, and biological activities of 2',5'-phosphorothioates from adenosine 5'-O-(2-thiotriphosphate) and adenosine 5'-O-(3-thiotriphosphate).

The chiral and achiral phosphorothioate analogues of 2',5'-oligoadenylates (2-5A) have been enzymatically synthesized from the Sp and Rp isomers of adenosine 5'-O-(2-thiotriphosphate) [(Sp)-ATP beta S and (Rp)-ATP beta S, respectively] and adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S) by 2-5A synthetase from L929 cells and lysed rabbit reticulocytes. These 2',5'-phosphorothioate analogues were separated, purified, and structurally characterized. While ATP gamma S and (Sp)-ATP beta S were as efficient substrates for the 2-5A synthetase as was ATP, (Rp)-ATP beta S was more than 50-fold less efficient a substrate. The beta- and gamma-phosphorothioates were more resistant to enzymatic hydrolysis than was authentic 2-5A. Compared to 2-5A, there were marked differences in the biological activities of the 2',5'-phosphorothioates as determined by (i) binding to 2-5A-dependent endoribonuclease (RNase L), (ii) activation of RNase L to hydrolyze RNA, and (iii) inhibition of protein synthesis in intact L929 cells. These studies extend previous reports on the elucidation of the stereochemical requirements of 2-5A synthetase and RNase L [Karikó, K., Sobol, R. W., Jr., Suhadolnik, L., Li, S. W., Reichenbach, N. L., Suhadolnik, R. J., Charubala, R., & Pfleiderer, W. (1987) Biochemistry (first of three papers in this issue); Karikó, K., Li, S. W., Sobol, R. W., Jr., Suhadolnik, R. J., Charubala, R., & Pfleiderer, W. (1987) Biochemistry (second of three papers in this issue)] with the phosphorothioate analogues of 2-5A.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1987

Copper staining: a five-minute protein stain for sodium dodecyl sulfate-polyacrylamide gels.

We present a new method for visualizing proteins electrophoresed in sodium dodecyl sulfate-polyacrylamide gels. After electrophoresis, gels are incubated in CuCl2 to produce a negative image of colorless protein bands against a semiopaque background. Gels are stained completely within 5 min, do not require destaining, and can be stored indefinitely without loss of the image. Because proteins are not permanently fixed within the gel, they can be quantitatively eluted after chelation of Cu with EDTA. The sensitivity of the CuCl2 stain falls between that of Coomassie blue and silver. We anticipate that CuCl2 will be useful in the rapid analysis of proteins by polyacrylamide gel electrophoresis and in the preparation of purified polypeptides by elution from gel slices.

Animals↗