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Biomedical subjects

C Lee

Publications and source records attributed to C Lee.

At least 901 records · Page 50Linked to original sources
PubMed1986

Alpha interferon in human pregnancy.

The concentration of interferon-alpha was measured by a specific two-site immunoradiometric assay in a variety of fluids and tissues collected during human pregnancy. Maternal blood and blood and tissues from non-pregnant adults contained little or no interferon-alpha. Fetal blood, fetal organs, placenta, membranes, amniotic fluid and decidua all contained significant and roughly equivalent amounts ranging from 1.1 to 10 u/ml (or per g of tissue). These findings demonstrate that the fetus and its immediate surroundings are permeated with interferon. It is suggested that this may play a role in regulation of the maternal-fetal graft relation.

Amniotic Fluid↗
PubMed1986

Cat area 17. I. Pattern of thalamic control of cortical layers.

Reversible inactivation of individual layers of the cat lateral geniculate and medial interlaminar nuclei was used to investigate the necessary and sufficient inputs for maintaining visually driven activity and receptive field properties in area 17. Neither orientation selectivity nor direction selectivity depends on any individual geniculate layer. We identified two groups of cortical layers on the basis of the pattern of thalamic inputs providing visual driving through the contralateral eye. One group, consisting of layers 4 and 6, has geniculate layer A as its only necessary and sufficient input. The other, consisting of supragranular layers, integrates at least two sufficient thalamic inputs, one of which is layer A. Several major receptive field properties are independently generated in these two groups of layers.

Animals↗
PubMed1986

Cat area 17. II. Response properties of infragranular layer neurons in the absence of supragranular layer activity.

Response properties of cells in the infragranular layers of cortical area 17 of the cat were examined in the absence of input from supragranular layers. Supragranular activity was silenced either reversibly by cooling the surface of cortex or permanently by making a cryogenic lesion of the supragranular layers. Visually driven responses of cells throughout the cortical column were recorded with a linear array of electrodes. Most infragranular layer cells continued to be visually responsive in the absence of supragranular layer input. These cells were similar to normal infragranular layer cells on measures of visual responsiveness, orientation selectivity, and direction selectivity. Special complex, but not standard complex, cells were absent in layer 5 when supragranular layers were destroyed. We found no evidence for a selective effect of removal of supragranular activity on the response properties of cells in layer 6. We propose that the intracolumnar projection from the supragranular layers drives the special complex cells of layer 5, but is not necessary for the visual driving of most other infragranular layer cells. This projection does not impose selectivity for stimulus orientation or direction on the remaining active cells of the infragranular layers.

Animals↗
PubMed1986

Cat area 17. III. Response properties and orientation anisotropies of corticotectal cells.

The receptive field properties of antidromically identified corticotectal (CT) cells in area 17 were explored in the paralyzed, anesthetized cat. To compare these with another population of infragranular cells, we also examined the receptive field properties of cells in layer 6. Sixty percent of our sample of CT cells showed increased response to increased stimulus length (length summation) and were classified as standard complex cells. The other 40% showed little or no length summation, were generally end stopped, and were classified as special complex cells. Standard and special complex CT cells have complementary orientation anisotropies: the distribution of orientation preferences of standard complex cells is biased toward obliquely oriented stimuli, whereas special complex cells are biased toward horizontally and vertically oriented stimuli. The receptive fields of the cells in our sample were primarily along the horizontal meridian so we cannot determine if these anisotropies are defined relative to the vertical meridian or relative to the meridian passing through the receptive field. The effects of these anisotropies in preferred orientation are minimized by the broad orientation tuning of CT cells. There was no simple relationship between the direction bias of CT cells and the reported direction bias of tectal cells. In contrast to the heterogeneity of corticotectal cells, layer 6 cells uniformly showed strong length summation, tight orientation tuning, and little spontaneous activity.

Animals↗
PubMed1986

Cat area 17. IV. Two types of corticotectal cells defined by controlling geniculate inputs.

The dependence of cat area 17 corticotectal (CT) cells on specific subdivisions of the dorsal lateral geniculate (LGN) and medial interlaminar nuclei (MIN) was examined using reversible inactivation techniques. Inactivation of layer C of the LGN or layer 1 of the MIN did not block visual activity of CT cells driven through the contralateral eye. Inactivation of layer A of the LGN revealed two populations of CT cells: one strongly dependent on layer A and one whose visually driven activity survived layer A inactivation. CT cells that responded best to short stimuli (special complex cells) were least dependent on layer A, whereas cells that responded best to long stimuli (standard complex cells) were most dependent on layer A. We propose a model of the intracortical circuitry of these two types of CT cells. Standard complex cells, which are heavily dependent on layer A, receive sustaining visual input through layers 4 and/or 6. Special complex cells, which are not dependent on any single layer of the lateral geniculate nucleus, receive sustaining visual input from supragranular layers.

Animals↗
PubMed1986

Early recovery of regional wall motion in patients following surgical revascularization after eight hours of acute coronary occlusion.

This study tests the hypothesis that failure of "successful" streptokinase with and without angioplasty to restore regional wall motion in patients with acute coronary occlusion is due to reperfusion injury that can be avoided in the surgical setting by control of the conditions of reperfusion and the composition of the reperfusate. Of 31 consecutive patients undergoing emergency coronary revascularization, 21 patients were reperfused medically with normal blood (streptokinase with or without angioplasty) following 4.5 +/- 0.4 hours of coronary occlusion in the coronary catheterization laboratory. Surgical reperfusion in 10 patients was with aspartate-glutamate-enriched blood cardioplegic solution during coronary artery bypass grafting after 8.5 +/- 0.5 hours (7.2 to 11.4 hours) of acute coronary occlusion. Hemodynamic instability was present in 5 of 10 surgical patients before operation and resulted from coronary occlusion, whereas 7 to 21 previously stable medical patients became unstable hemodynamically following revascularization with normal blood. Surgical patients evolved fewer electrocardiographically determined infarctions (7/10 versus 21/21, p less than 0.05), had fewer reperfusion ventricular arrhythmias (0/10 versus 9/21, p less than 0.05), had somewhat better global ejection fractions (47% versus 41%), and had shorter hospitalization times (8.3 versus 10.7 days, p less than 0.05); in addition, they all showed significant segmental contractility at discharge (10/10 versus 2/21, p less than 0.05), despite delay of revascularization up to 11 hours. No deaths occurred. These studies imply that acute coronary occlusion is treated best by control of the conditions of reperfusion and the composition of the reperfusate.

Aspartic Acid↗
PubMed1986

Magnetic resonance and computed tomographic imaging of mass lesions of the cerebral ventricles. A prospective comparative study.

This study was undertaken to investigate the relative merits of magnetic resonance (MR) imaging and computed tomography (CT) in the evaluation of primary lesions of the cerebral ventricles. Since 1982, 14 patients, 7 males and 7 females, aged 8 to 68 years were diagnosed as harboring ventricular mass lesions. Eight masses were located in the lateral, 5 in the third, and one in the fourth ventricle. The diagnostic contribution and relative merits of two imaging modalities were compared in each case. In 57 per cent of cases the CT scan was of superior diagnostic value, and in 21 per cent of the patients MR imaging proved to be either more sensitive or specific than CT scanning. The availability of intravenous contrast agents for CT and not MR, as well as the capability of CT to definitely identify lesion calcification, accounted for the better performance of CT scanning in this series of patients.

Adult↗
PubMed1986

Aggressive natural killer cell leukemia in an adult with establishment of an NK cell line.

There have been many reports of cases in which chronic increases in the numbers of natural killer (NK) cells have been reported. Whether this is reactive or neoplastic in nature has been debated. We report the first case of an aggressive NK cell leukemia in an adult with establishment of an NK cell line. A 70-year-old man had two spontaneous episodes of jejunal perforation and one month later developed a severe febrile illness with moderate splenomegaly. Hemoglobin was 13.1 g/L, and WBC count was 1.8 X 10(9)/L with 2% large granular lymphocytes (LGLs). Platelet count was 143 X 10(9)/L; prothrombin time (PT) and partial thromboplastin time (PTT) were normal. Bone marrow was infiltrated with 25% to 30% LGLs; serum lysozyme was normal. Serum LDH was initially 1,191 U/L and rose to 6,408 (normal 240 to 525 U/L). Ten days later, the WBC count increased to 99.9 X 10(9)/L with 70% LGL cells; the PT and PTT increased, and the platelet count dropped. No bacterial or viral cause of fever was identified. The cells from peripheral blood were LGLs that stained positively for acid phosphatase. All of the LGLs reacted with a monoclonal antibody reactive with NK cells (LEU-11b). Functionally, the patient's peripheral blood mononuclear cells (PBMs) demonstrated 100 times more lytic activity against K562 tumor cell lines than did normal PBMs. The patient's PBMs were propagated in vitro. The cultured cells showed the morphological, cytochemical, immunological, and functional characteristics of NK cells. In addition, partial trisomy involving chromosome 1 q with duplication in regions of q21 through q31 was observed in all metaphases analyzed. The extra chromosome 1q with duplication in regions q21 through q31 was translocated to the p-terminal of chromosome 5. One percent to 5% of normal PBMs comprise NK cells; in most cases, leukemias arise from normal phenotypic counterparts. This case demonstrated that aggressive NK cell leukemia may occur in adults. In addition, the chromosomal abnormalities suggest that this is not a reactive process but a malignancy.

Aged↗
PubMed1985

[Rotavirus and pararotavirus infections in adults. Analysis of a nosocomial infection and some sporadic cases].

A nosocomial infection in adults due to rotavirus is described. The identity of the infecting rotavirus strains was demonstrated by genomic dsRNA electrophoresis. At an interval of 19 days another patient in the same hospital developed a pararotavirus infection. Pararotaviruses or rotavirus-like agents are antigenetically distinct from rotaviruses and thus cannot be detected at present by the available antibody mediated antigen detection systems. The current prevalence of pararotavirus infections in adults is unknown in Switzerland. The question whether there is a relationship between the small nosocomial rotavirus epidemic and the sporadic pararotavirus infection remains speculative. We also performed microbiological workups of 394 fecal samples from outpatients with diarrhoea. During the study period from January to April 1984 rotaviruses were the third most frequent aetiological agent, after salmonella and campylobacter, in acute adult gastroenteritis. Selecting the bacteriologically negative fecal samples with a watery and non-bloody aspect, rotaviruses were found in 30%.

Adult↗
PubMed1985

Differential antiproliferative actions of 2',5' oligo A trimer core and its cordycepin analogue on human tumor cells.

The antiproliferative effect of 2',5' A3 core and 2',5'-3'dA3 (cordycepin trimer) core was measured in 8 human tumor cell lines. Cells were treated in a dose-response manner for 72 hr and the concentration of drug necessary to inhibit cell growth 50% (GI50) was determined. A wide range of sensitivities to these drugs was found, even among tumors of the same histological type. The cell lines showed different sensitivities and dose-response curves to the 2',5'A3 and 2',5'-3'dA3 cores. Uptake studies of the 2',5'A3 and 2',5'-3'dA3 cores, using high-pressure liquid chromatography, demonstrated that both cores were rapidly degraded in the tissue culture medium and taken up as adenosine or cordycepin, respectively. There was a direct correlation between the uptake of cordycepin and the antiproliferative effect. In contrast, there was no correlation between cell sensitivity and the uptake of the 2',5'A3 core degradation products. Analysis of intracellular nucleosides and nucleotides indicated that differences in intracellular metabolism of adenosine might explain the different sensitivities of the various cell lines to 2',5'A3 core. Molar equivalent concentrations of adenosine and cordycepin inhibited cell growth; however, equimolar concentrations of these nucleosides were not effective. In addition, the antiproliferative effect of both core compounds and their corresponding nucleosides could be potentiated by the addition of the adenosine deaminase inhibitor, deoxycoformycin. The results indicate that these cores act as prodrugs and that the active metabolites are their corresponding nucleosides.

Adenine Nucleotides↗
PubMed1985

Release of thioltransferase from rabbit polymorphonuclear leucocytes by immune complex in vitro and inhibition of the enzyme by chloramphenicol.

Immune complex induced the release of thioltransferase from rabbit peritoneal exudates polymorphonuclear leucocytes in vitro. The release of thioltransferase occurs from viable cells and does not depend on a cytolysis. The catalytic activity of the released enzyme with S-sulfocysteine and glutathione as substrates had a distinct optimum pH at 7.6. On the contrary, opsonized zymosan was not effective as a stimulus for the liberation of thioltransferase from polymorphonuclear leucocytes. Thioltransferase liberated by the stimulation with immune complex was inhibited by chloramphenicol, but not by bacitracin. The inhibition was non-competitive (apparent Ki of 0.2 mM).

Animals↗
PubMed1985

2',5'-Oligoadenylates chiral at phosphorus: enzymatic synthesis, properties, and biological activities of 2',5'-phosphorothioate trimer and tetramer analogues synthesized from (SP)-ATP alpha S.

The enzymatic synthesis and characterization of (RP)-2',5'-AMPS trimer and tetramer (SP)-5'-O-(1-thiotriphosphates) from chirally substituted (SP)-[alpha-35S]ATP alpha S by 2',5'-oligoadenylate synthetase from interferon-treated L cell extracts are described. The (RP)-ATP alpha S isomer is not a substrate for the synthetase. The identification of the trimer and tetramer analogues (molar ratio 70:30) was accomplished by high-performance liquid chromatography and subsequent separation by charge using DEAE-cellulose thin-layer chromatography. The digestion of the analogue by snake venom phosphodiesterase I (SVPD) to [alpha-35S]ATP alpha S and [35S]AMPS but not by T2 RNase demonstrated the presence of the 2',5' linkage. The assignment of RP configuration of the 2',5'-phosphorothiodiester linkage was based on the highly specific stereoselectivity of SVPD for RP diastereomers [Burgers, P. M. J., & Eckstein, F. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 4978-4800; Bryant, F. R., & Benkovic, S. J. (1979) Biochemistry 18, 2825-2828; Nelson, P. S., Bach, C. T., & Verheyden, J. P. H. (1984) J. Org. Chem. 49, 2314-2317]. This suggests that the synthesis of the phosphorothioate analogues proceeded via inversion of configuration at the chiral phosphorus of (SP)-ATP alpha S. The putative (RP)-2',5'-AMPS tetramer (SP)-5'-O-(1-thiotriphosphate) displaced the 2',5'-p3A4[32P]pCp analogue from 2',5'-oligoadenylate-dependent endonuclease 5 times more efficiently than did equimolar concentrations of authentic 2',5'-adenylate tetramer triphosphate. Furthermore, in studies using the calcium phosphate coprecipitation technique, the 2',5'-phosphorothioate trimer and tetramer analogues inhibited protein synthesis better than did 2',5'-adenylate trimer and tetramer triphosphates.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗
PubMed1985

Metabolic action of prolactin in regressing prostate: independent of androgen action.

The mechanism of the observed synergistic effect of prolactin and androgen on the lateral lobe of the rat prostate is not established. The observation that prolactin alone delayed the rate of loss of weight, protein, and DNA of the lateral lobe in castrated rats has led us to question the assumption that the effect of prolactin is produced by a modification of recognized androgen-induced intracellular changes. The present study was conducted to explore whether or not the sites of prolactin action in the rat prostate coincided with those recognized as the androgen effect. Two anterior pituitaries from female donors were grafted under the right renal capsule of adult male Sprague-Dawley rats. Seven days later, bilateral orchiectomy and unilateral nephrectomy were performed in these rats. In one half of the animals, the kidney bearing the pituitary grafts was removed. In the other half, the contralateral kidney was removed. Seven days following the orchiectomy-nephrectomy, animals bearing the pituitary grafts had a higher level of serum prolactin (93 +/- 7 ng/ml, mean +/- SE) than in those without the graft (26 +/- 3 ng/ml). This condition of hyperprolactinemia was associated with the delay of castration-induced regression in the lateral prostate. The rate of protein degradation, as judged by the amount of radioactivity remaining in the tissue following a single i.v. pulse of 3H-leucine 24 hr before orchiectomy-nephrectomy, was significantly slower in the lateral prostate in graft-bearing animals than in those without grafts. However, the rate of protein synthesis, as judged by both in vitro and in vivo incorporation of 3H-leucine into the protein fractions of the prostate, was not significantly different between the two groups. Nor was the total activity of cathespin D in the lateral prostate different. These results were not consistent with parameters known as the effect mediated through androgen-controlled mechanisms. We therefore conclude that the action of prolactin in the regressing rat prostate is probably not mediated through the action of androgen.

Androgens↗
PubMed1985

Reduction in prostatic concentration of endogenous dihydrotestosterone in rats by hyperprolactinemia.

Persistently high levels of circulating prolactin can be achieved in male rats when pituitaries from female donors are grafted under the renal capsule. Enhanced growth of the lateral prostate can be accomplished by an apparent synergistic effect of excess prolactin with subphysiologic doses of testosterone. To define this effect we measured the endogenous dihydrotestosterone (DHT) concentrations in rat prostate lobes. Twenty Sprague-Dawley male rats (250 g) were castrated and given subcutaneous implants of silastic tubing filled with 1 cm of crystalline testosterone. Ten of these rats simultaneously received two pituitary grafts under the renal capsule. The remaining ten rats received intrarenal skeletal muscle grafts as controls. Four weeks later, the weight (mg +/- SE) of the ventral and dorsal lobes were not significantly different between the two groups, while the lateral lobe was significantly (P less than 0.01) heavier in rats with pituitary grafts (121.4 +/- 7.5) than in controls (81.7 +/- 10.4). Endogenous DHT in the tissue extracts was determined by radioimmunoassay following KMnO4 treatment to eliminate testosterone. The concentration of DHT (ng/g tissue +/- SE) was significantly (P less than 0.01) lower in the lateral prostate of graft-bearing animals (4.40 +/- 0.29) than in the controls (5.98 +/- 0.34). These results indicate that, in the rat, hyperprolactinemia induced by pituitary grafts is associated with a heavier lateral prostate and a lower concentration of endogenous DHT in that tissue. These results also suggest that the action of prolactin in the rat prostate is not mediated through the action of androgen.

Animals↗