Biomedical subjects

C Y Li

Publications and source records attributed to C Y Li.

At least 19 recordsLinked to original sources

PubMed1992

Kinetic characterization of reductant dependent processes of iron mobilization from endocytic vesicles.

The reductant dependence of iron mobilization from isolated rabbit reticulocyte endosomes containing diferric transferrin is reported. The kinetic effects of acidification by a H(+)-ATPase are eliminated by incubating the endosomes at pH 6.0 in the presence of 15 microM FCCP to acidify the intravesicular milieu and to dissociate 59Fe(III) from transferrin. In the absence of reductants, iron is not released from the vesicles, and iron leakage is negligible. The second-order dependence of rate constants and amounts of 59Fe mobilized from endosomes using ascorbate, ferrocyanide, or NADH are consistent with reversible mechanisms. The estimated apparent first-order rate constant for mobilization by ascorbate is (2.7 +/- 0.4) x 10(-3) s-1 in contrast to (3.2 +/- 0.1) x 10(-4) s-1 for NADH and (3.5 +/- 0.6) x 10(-4) s-1 for ferrocyanide. These results support models where multiple reactions are involved in complex processes leading to iron transfer and membrane translocation. A type II NADH dehydrogenase (diaphorase) is present on the endosome outer membrane. The kinetics of extravesicular ferricyanide reduction indicate a bimolecular-bimolecular steady-state mechanism with substrate inhibition. Ferricyanide inhibition of 59Fe mobilization is not detected. Significant differences between mobilization and ferricyanide reduction kinetics indicate that the diaphorase is not involved in 59Fe(III) reduction. Sequential additions of NADH followed by ascorbate or vice versa indicate a minimum of two sites of 59Fe(III) residence; one site available to reducing equivalents from ascorbate and a different site available to NADH. Sequential additions using ferrocyanide and the other reductants suggest interactions among sites available for reduction. Inhibition of ascorbate-mediated mobilization by DCCD and enhancement of ferrocyanide and NADH-mediated mobilization suggest a role for a moiety with characteristics of a proton pore similar to that of the H(+)-ATPase. These data provide significant constraints on models of iron reduction, translocation, and mobilization by endocytic vesicles.

Animals↗

PubMed1992

Leukemic manifestation in a case of alpha-chain disease with multiple polypoid intestinal lymphocytic lymphoma.

We describe a female aborigine from Taiwan with alpha-chain disease associated with multiple polypoid intestinal lymphocytic lymphoma and leukemic manifestation. Initially, the patient experienced intermittent diarrhea, abdominal pain, and leukemic manifestation. No evidence of bone marrow involvement was found. Alpha-chain protein was demonstrated in the serum. Gastroendoscopy and a series of radiographs of the small intestine revealed multiple polypoid tumors involving the entire length of the small intestine. Duodenal biopsy showed diffuse lymphocytic lymphoma. Immunohistochemical staining of tumor samples revealed features typical of alpha-chain disease. Cytogenetic analysis showed the same abnormal karyotypes of neoplastic clones in intestinal tumor cells and in circulating leukemic cells. The data suggest that alpha-chain disease can present initially with intestinal multiple polypoid lymphocytic lymphoma and leukemic manifestation without evidence of bone marrow involvement. The data also support the homing theory of lymphomas from mucosa-associated lymphoid tissue.

Adult↗

PubMed1992

Is persistent polyclonal B lymphocytosis caused by Epstein-Barr virus? A study with polymerase chain reaction and in situ hybridization.

Previous reports of patients with persistent polyclonal B lymphocytosis have found associations with female sex, cigarette smoking, HLA-DR7 phenotype, and moderate elevation of peripheral blood polyclonal B lymphocytes. The presence of binucleated cells and atypical lymphocytes in the peripheral blood of these patients was highly suggestive of a viral infection, such as with the Epstein-Barr virus. We report a 47-year-old asymptomatic woman who was incidentally found to have persistent polyclonal B lymphocytosis and serum IgG against virus capsid antigen (VCA) and Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) of EBV. The presence of EBV was investigated in the peripheral blood lymphocytes from this patient by in situ hybridization and polymerase chain reaction methods. EBV DNA was demonstrated in the lymphocyte fraction by polymerase chain reaction, and it was further located in lymphoid cells by in situ hybridization. These results indicate that persistent polyclonal B lymphocytosis is strongly associated with EBV.

B-Lymphocytes↗

PubMed1992

Evidence for coincident mutations in human lymphoblast clones selected for functional loss of a thymidine kinase gene.

A mitotic "recombination-competent state" inducible by x-irradiation is thought to exist in yeast. We sought evidence for such a process in mammalian cells by examining the occurrence of mutations at unlinked loci in clones derived from a human lymphoblast cell line. A total of 169 independent clones that arose spontaneously or after exposure to x-rays or ethyl methanesulfonate were selected for new somatic mutations at the thymidine kinase gene on chromosome 17q. They were subsequently screened for coincident mutations by use of variable-number-of-tandem-repeat probes located on different chromosomes. Three coincident mutations were positively identified by Southern analysis on chromosomes 7 and 14; they included one that produced a new allele and two that caused loss of allele heterozygosity. Densitometric analysis of the latter two indicated the presence of two copies of the remaining allele. Several possible coincident genetic events were also observed on chromosome 17. These findings revealed a coincident mutant fraction of about 10(-2)/cell, whereas the expected mutation fraction at these loci is less than 10(-4)/cell. These results may thus provide the first molecular evidence that a "global" mutational process capable of inducing genetic instability exists in mammalian cells.

Blotting, Southern↗

PubMed1992

Direct sequencing of tobacco chloroplast genome by the polymerase chain reaction.

We have developed a polymerase chain reaction (PCR) method for sequencing of tobacco chloroplast genome. In a mixture containing chloroplast DNA, 5'-end-labeled oligonucleotide primer, Taq DNA polymerase and reaction buffer, we were able to sequence a segment of chloroplast 16S rRNA gene. The results showed that the 750 bp of DNA sequenced were identical to the sequence reported, indicating that direct sequencing method that we have developed is useful for the sequencing of chloroplast genome. To analyze the chloroplast genome more rapidly in those in vitro grown plantlets, we also developed a simple method which is applicable for the amplifications and sequencing of chloroplast 16S rRNA fragment from either 0.15 g of tobacco leaf or stem tissue. The readable sequences obtained from the presented methods were consistent with the published sequence.

Base Sequence↗

PubMed1992

Molecular mechanisms of spontaneous and induced loss of heterozygosity in human cells in vitro.

The human TK6 lymphoblast cell line is heteroallelic at the thymidine kinase (TK) locus, with one functional and one nonfunctional allele. Cells that have undergone loss of heterozygosity (LOH) at TK can be selected and cloned in an in vitro assay. In order to study the extent of LOH, we have analyzed a total of 166 thymidine kinase-deficient mutants that arose either spontaneously or following induction by X-ray or ethyl methane sulfonate (EMS) using DNA probes in and around the TK gene on chromosome 17. Two distinct groups of mutants with different doubling times were identified. Among slow-growth mutants, the predominant change for both spontaneous and induced mutants was LOH that generally extended through the entire TK gene to both proximal and distal markers on 17q. While the majority of both spontaneous and X-ray-induced normal-growth mutants showed LOH, this was considerably more localized in scale for X-ray-induced mutants, which rarely involved the distal marker. LOH was rare among EMS-induced normal-growth mutants. LOH was never observed with a 17p marker, indicating that nondisjunctional events were not involved in any of the mutant clones examined. Densitometric analysis of the LOH mutants indicated mitotic recombination was a likely mechanism in more than half the spontaneous LOH mutants in both groups, whereas most induced mutants appeared to arise from simple deletions.

Cell Line, Transformed↗

PubMed1992

Detection of surface antigen expression of pre- and post-cultured normal adult's bone marrow cells by using ABC technique and its significance.

The expression of surface antigens on both normal adult's bone marrow and multipotential progenitor cells (CFU-Mix) was detected by use of ABC technique. The culture system of CFU-Mix was an ideal model for studying the differentiation direction of hematopoietic cells. The monoclonal antibodies (McAb) CD3, CD4, CD8 specific for T-lymphocytic lineage, CD22 for B-lymphocytic lineage and CD11, CD13, CD14 for granulocytomonocytic lineage were all demonstrated in certain proportion in cultured CFU-Mix, which might be associated with the control of hematopoiesis. A decrease in the positive rate of OKT9 and CD34 in cultured cells might be related to the differentiation of hematopoietic cells. SZ-2 and SZ-21 could contribute to the identification of the presence of megakaryocytes in CFU-Mix.

Adult↗

PubMed1992

Heterogeneity of hairy cell tartrate-resistant acid phosphatase.

The human nonerythrocytic acid phosphatases (AcP) are composed of seven distinct activity bands in nondenaturing polyacrylamide gel electrophoresis (PAGE) when stained using either 1-naphthyl phosphate or naphthol ASBI phosphate as substrate. They are numbered 0, 1, 2, 3, 3b, 4, and 5 according to their increasing mobility toward the cathode in acidic conditions. Of these, only the most cationic "band 5" is tartrate resistant (TRAcP). When naphthol ASBI phosphate is used as substrate, AcP activity can also be stained in situ. In the presence of tartrate, activity remains strong in the hairy cells (HC) of hairy cell leukemia (HCL). Thus, the TRAcP stain has remained a reliable marker for HC. To investigate the function of TRAcP in HC, we purified two isoforms of TRAcP from HCL spleen tissue and found them to have similar substrate specificities and inhibitor sensitivities. In this report, we describe in detail the methods for TRAcP purification and compare some of the structural properties of the two isoforms to reinforce the concept that human TRAcP is a heterogeneous group of related enzymes. Band 5 represented only 15-20% of the total TRAcP extracted from HCL spleen. The remaining 80% of TRAcP hydrolyzed p-nitrophenyl phosphate but not naphthol ASBI phosphate and was not detectable in acidic, nondenaturing PAGE gels. Band 5 was solubilized from tissue using 500 mmol/L NaCl after previous extraction with 0.5% (v/v) NP-40 removed most other AcP and TRAcP activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗

PubMed1992

Extensive disinhibitory region beyond the classical receptive field of cat retinal ganglion cells.

Forty-three single fibres were recorded from cat optic tract. They were tested with flashing lines of different lengths and/or spots of different dimensions. The area of centre excitation and of surround inhibition were represented in the length (or dimension)-response functions by the steep rising and falling phases, respectively. For most of the cells, a secondary gentle rise was seen when the stimulus extended beyond the inhibitory surround, indicating an extensive disinhibitory region (DIR) outside the classical receptive field (RF). Disinhibition appeared and developed concurrently with surround inhibition at stimulus intensities between 3 and 30 cd/m2, being represented in the phasic or the tonic component of responses depending on the cell type recorded.

Animals↗

PubMed1992

Transient neonatal hyperthyrotropinaemia.

Of 48 consecutive newborns with elevated umbilical venous plasma thyrotropin (TSH) concentration, only two (4%) were subsequently proved to have congenital hypothyroidism, while the other 46 had transient elevation of TSH. Compared with matched controls, these 46 newborns were all delivered vaginally (P less than 0.0003) and had a longer second stage of labour (P less than 0.002), together with higher incidences of nuchal encirclement of the cord (P less than 0.05) as well as female babies (P less than 0.05). There was no difference in the incidence of antenatal complications, mean gestational age, birth weight, or birth asphyxia. There were no small-for-gestational age infants in the study group, while four were found in the controls. The results indicate that elevated umbilical cord plasma TSH concentration may represent a response to the stress of difficult or complicated delivery in the healthy appropriate- or large-for-gestational age newborn who does not have congenital hypothyroidism.

Delivery, Obstetric↗

PubMed1992

Value of immunohistochemistry in the diagnosis of leukemia cutis: study of 54 cases using paraffin-section markers.

A grave prognosis is usually associated with leukemic skin infiltrates (leukemia cutis). However, some leukemic skin infiltrates are clinically similar to reactive non-leukemic infiltrates in patients with leukemia; thus it is of great importance to distinguish them. Fifty-four cases which were thought clinically to be leukemia cutis underwent immunophenotyping with a panel of nine T, B, monocytic, and macrophage markers using paraffin sections. Immunohistochemistry helped identify 44 cases with leukemia cutis and 10 with reactive infiltrates. In all cases of leukemia cutis, the staining patterns of skin infiltrates were concordant with cell type in the bone marrow. Furthermore, the panel of markers was usually helpful in distinguishing reactive from leukemia infiltrates, especially in cases with chronic lymphatic leukemia. Immunohistochemistry is a valuable adjunct in histopathologic differentiation of skin infiltrates in most cases of leukemia. With formalin-fixed, paraffin-embedded biopsies, we recommend that CD45 (LCA), CD45RO (UCHL-1), CD3, CD20 (L-26), CD43 (Leu-22), CD68 (KP-1), lysozyme, and chloroacetate esterase be considered in cases of systemic leukemia with cutaneous papules and nodules that prove difficult to interpret with routine section.

Acute Disease↗

PubMed1992

Permanent stained preparations of synovial fluid for detection of calcium compounds using alizarin red S.

Permanent preparations of air dried synovial fluids were prepared by staining calcium compounds with alizarin red S stain; each slide was coverslipped with Permount. Variables studied were: (a) concentration of the solution of alizarin red S, (b) pH of staining solution, (c) time of incubation in staining solution and aqueous and ethanolic content of staining solution. The staining effect of each solution was tested on calcium pyrophosphate dihydrate, calcium oxalate, apatite and monosodium urate (MSU). Of all the solutions, best results were obtained with 0.25% alizarin red S in 50% ethanol at pH 7.0 for 30 min. With this solution, the calcium-containing compounds were well stained. MSU did not stain and still preserved negative birefringence on polarization. Fixation of smears with ethanol served a double purpose: It fixed the slides without dissolving or removing MSU or the calcium compounds, yet it did dissolve five corticosteroids commonly used for intra-articular injection which may interfere with interpretation of compensated polarized light microscopy of synovial fluids.

Anthraquinones↗

PubMed1992

[Effects of various recombinant human hematopoietic growth factors on proliferation of blast cells in acute myeloid leukemia in vitro].

In vitro proliferative response of the blast cells from 21 AML patients to hematopoietic growth factors (IL-3, GM-CSF, G-CSF and MCSF) was investigated. Proliferation of AML cells in the majority of cases was induced or promoted by one or more CSFs, among which the stimulation of IL-3 was the most effective. Spontaneous proliferation of the blast cells was also observed in half of the cases and could be inhibited as well as promoted by some CSFs. It is suggested that in vitro proliferation of AML cells varies from patient to patient and that CSF plays important roles in leukemogenesis.

Adolescent↗

PubMed1992

[Optimal pulmonary ventilation determined by the relation between end-tidal CO2 and arterial blood pressure in artificially respirated cat].

End-tidal CO2 (ET-CO2) provides a continuous and sensitive monitoring of proper pulmonary ventilation in artificially ventilated animals during single unit recordings of the central nervous system. To determine a reliable standard of ET-CO2 in anesthetized and paralyzed animal, the relationship between ET-CO2 and arterial blood pressure (ABP) was observed in cat under different ventilation level. The results showed that ABP changed tremendously with variation in ventilation, but remained constant at a normal level as long as ET-CO2 was maintained within the range between 4.0-5.0%, i.e. optimally at 4.5 +/- 0.5%.

Animals↗

PubMed1992

Protein-tyrosine phosphatase activity of hairy cell tartrate-resistant acid phosphatase.

Tartrate-resistant acid phosphatase (TRAcP) is a reliable cytochemical marker for the diagnosis of hairy cell leukemia (HCL). The enzyme has been the subject of much biochemical investigation yet its function in the hairy cells (HC) is still unknown. Two TRAcPs have been purified from HCL spleen tissues by a series of chromatographic separations. The two enzymes, provisionally called peak 1 and peak 2, had specific activities of greater than 600 U/mg and 800 U/mg respectively when p-nitrophenyl phosphate (p-NPP) was used as substrate and had Km values in the range of 1 to 5 mM p-NPP. The two TRAcPs had the same substrate specificities and inhibitor sensitivities, therefore could be isoforms of the same enzyme. Their pH optima were between 5 and 6 for all substrates tested including the phosphotyrosine-containing peptide, Raytide, which was still hydrolyzed efficiently at neutral pH. Neither phosphoserine nor phosphoserine-containing casein were hydrolyzed by either enzyme. The TRAcPs of HC may thus be capable of functioning as protein-tyrosine phosphatases (PTP). High activity of a PTP could regulate the activities of protein-tyrosine kinases and thereby influence the growth and differentiation of the hairy cells.

Acid Phosphatase↗

PubMed1991

Clinical and electrophysiological aspects of acute paralytic disease of children and young adults in northern China.

Acute peripheral nervous system diseases leading to paralysis in children are rare in Europe and the USA, whereas epidemics of a Guillain-Barré-like syndrome occur annually among children in rural parts of northern China. To clarify the features of this disorder 36 patients, aged 15 months to 37 years (median 7) with this syndrome were investigated; 91% were from rural areas. In 47%, a prodromal illness was reported in the preceding 4 weeks. Leg weakness and resistance to neck flexion were the earliest symptoms. The weakness ascended rapidly and symmetrically to affect the arms and respiratory muscles, with maximum weakness occurring a mean of 6 days after onset of weakness. Bulbar weakness occurred in 61% of patients, but only 1 had extraocular paresis. Respiratory assistance was needed by 31% of patients. Tendon reflexes were lost as weakness developed. 42% of patients had raised concentrations of protein in the cerebrospinal fluid, and the mean cell count was 3 cells/microliters (range 0-12/microliters). Electrodiagnostic studies in 22 patients showed severe reductions in motor evoked amplitudes from distal stimulation. Sensory action potentials were normal. Electromyography revealed denervation potentials in limb muscles. The distinctive epidemiological, clinical, and neurophysiological characteristics of this illness suggest that the disorder is different from both Guillain-Barré syndrome and poliomyelitis. The neurophysiological findings support the hypothesis that the disorder is a reversible distal motor nerve terminal or anterior horn cell lesion.

Acute Disease↗

PubMed1991

Unusual presentation of extranodal peripheral T-cell lymphomas with multiple paraneoplastic features.

Three patients with extranodal peripheral T-cell lymphoma and a distinctive clinical presentation are described. They had acute onset of fever, weight loss, progressive liver failure, bleeding diathesis, pancytopenia, and myelodysplastic changes in the bone marrow. Each patient had one or more paraneoplastic complications: severe rhabdomyolysis with myoglobinuria and secondary renal failure, cutaneous vasculitis, gluten-sensitive enteropathy, polyserositis, and increased macrophages with hemophagocytic activity. They did not have peripheral lymphadenopathy. The complex clinical presentations simulated collagen vascular disorders, systemic infections, or severe liver disease rather than a malignant lymphoma. Routine histologic studies revealed a small population of lymphoma cells in the bone marrow, spleen, and liver. Immunophenotyping studies demonstrated their T-cell phenotype, and cytogenetic analysis showed the clonality in Patients 1 and 2; clonal T-cell receptor gene rearrangement was found in Patients 2 and 3. These studies should be considered in the evaluation of patients with constitutional symptoms, liver failure, coagulopathy, and pancytopenia even in the absence of peripheral lymphadenopathy.

Adult↗

PubMed1991

The neurophysiological correlates of colour and brightness contrast in lateral geniculate neurons. I. Population analysis.

The colour of an object is changed by surround colours so that the perceived colour is shifted in a direction complementary to the surround colour. To investigate the physiological mechanism underlying this phenomenon, we recorded from 260 neurons in the parvo-cellular lateral geniculate nucleus (P-LGN) of anaesthetized monkeys (Macaca fascicularis), and measured their responses to 1.0-2.0 degrees diameter spots of equiluminant light of various spectral composition, centered over their receptive field (spectral response function, SRF). Five classes of colour opponent neurons and two groups of light inhibited cells were distinguished following the classification proposed by Creutzfeldt et al. (1979). In each cell we repeated the SRF measurement while an outer surround (inner diameter 5 degrees, outer diameter 20 degrees) was continuously illuminated with blue (452 nm) or red (664 nm) light of the same luminance as the center spots. The 1.0-1.5 degree gap between the center and the surround was illuminated with a dim white background light (0.5-1cd/m2). During blue surround illumination, neurons with an excitatory input from S- or M-cones (narrow- and wide-band/short-wavelength sensitive cells, NS- and WS-cells, respectively) showed a strong attenuation of responses to blue and green center spots, while their maintained discharge rate (MDR) increased. During red surround illumination the on-minus-off-responses of NS- and WS-cells showed a clear increment. L-cone excited WL-cells (wide-band/long-wavelength sensitive) showed a decrement of on-responses to red, yellow and green center spots during red surround illumination and, in the majority, also an increment of MDR. The response attenuation of narrow-band/long-wave-length sensitive (NL)-cells was more variable, but their on-minus-off-responses were also clearly reduced in the average during red surrounds. Blue surround illumination affected WL-cell responses little and less consistently than those of NL-cells, but often broadened the SRF also in the WL-cells towards shorter wavelengths. The M-cone excited and S-cone suppressed WM-cells were strongly suppressed by blue but only little affected by red surround illumination. The changes of spectral responsiveness came out clearly in the group averages of the different cell classes, but showed some variation between individual cells in each group. The zero-crossing wavelengths derived from on-minus-off-responses were also characteristically shifted towards wavelengths complementary to those of the surround.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗