Biomedical subjects

J Y Lin

Publications and source records attributed to J Y Lin.

At least 19 recordsLinked to original sources

PubMed1992

Defining the carbohydrate specificities of Abrus precatorius agglutinin as T (Gal beta 1----3GalNAc) greater than I/II (Gal beta 1----3/4GlcNAc).

The combining site of the nontoxic carbohydrate binding protein (Abrus precatorius agglutinin, APA) purified from the needs of Abrus precatorius (Jequirity bean), was studied by quantitative precipitin and precipitin-inhibition assays. Of 26 glycoproteins and polysaccharides tested, all, except sialic acid-containing glycoproteins and desialized ovine salivary glycoproteins, reacted strongly with the lectin, and precipitated over 70% of the lectin added, indicating that APA has a broad range of affinity and recognizes (internal) Gal beta 1----sequences of carbohydrate chains. The strong reaction with desialized porcine and rat salivary glycoproteins as well as pneumococcus type XIV polysaccharide suggests that APA has affinity for one or more of the following carbohydrate sequences: Thomsen-Friedenreich (T, Gal beta 1----3GalNAc), blood group precursor type I and/or type II (Gal beta 1----3/4GlcNAc) disaccharide determinants of complex carbohydrates. Among the oligosaccharides tested, the T structure was the best inhibitor; it was 2.4 and 3.2 times more active than type II and type I sequences, respectively. The blood group I Ma-active trisaccharide, Gal beta 1----4GlcNAc beta 1----6Gal, was about as active as the corresponding disaccharide (II). From the above results, we conclude that the size of the combining site of the A. precatorius agglutinin is probably as large as a disaccharide and most strongly complementary to the Gal beta 1----3GalNAc (T determinant) sequence. The carbohydrate specificities of this lectin will be further investigated once the related oligosaccharide structures become available.

Binding, Competitive↗

PubMed1992

Low calcium/high magnesium medium increases activities of hypothalamic arcuate and suprachiasmatic neurons in brain tissue slices.

Extracellular single-unit recording was conducted in hypothalamic arcuate (ARC) and suprachiasmatic nucleus (SCN) in rat brain slices. The perifusion medium was switched from normal artificial cerebrospinal fluid (ACSF) to ACSF containing low Ca2+ and high Mg2+ to test the effect of extracellular calcium on the spontaneous activities of these neurons and their responses to some test agents. It was found that almost all of the ARC and SCN units tested increased their firing rates in low Ca2+, high Mg2+ ACSF, and exhibited more significant responses to excitatory test agents. The effects of low Ca2+, high Mg2+ ACSF were repeatable and reversible. The results suggest that extracellular Ca2+ is essential in maintaining the membrane stability of most hypothalamic neurons and most agents tested are acting postsynaptically on the unit recorded.

Action Potentials↗

PubMed1992

The complete primary structure of abrin-a B chain.

The complete 267 amino acid sequence of abrin-a B chain was determined by analysis of peptides obtained by digestion with trypsin, chymotrypsin, lysyl endopeptidase, Staphylococcus aureus V8 protease and thermolysin. The sequence is not identical with that predicted previously by nucleotide sequencing, indicating the presence of isoforms of abrin. Comparison of the amino acid sequence of abrin-a B chain with that of ricin-D B chain reveals a high degree of sequence identity (59%). Abrin-a B chain appears to consist of two domains, each domain with subdomains (alpha, beta, gamma) of about 40 amino acid residues.

Abrin↗

PubMed1992

Macrophage cytotoxicity against Entamoeba histolytica trophozoites is mediated by nitric oxide from L-arginine.

The killing of Entamoeba histolytica trophozoites by phagocytes involves oxidative and nonoxidative mediators. In this study, we determine whether L-arginine-derived nitric oxide (NO) is involved in the killing of E. histolytica trophozoites by activated murine macrophages in vitro. Elicited peritoneal and bone marrow-derived macrophages activated with IFN-gamma alone or with IFN-gamma and LPS killed 62 to 73% of amebae, concomitant with increased levels of nitrate (NO2). Depletion of L-arginine by addition of arginase to culture medium abrogated macrophage amebicidal activity. NG-monomethyl L-arginine, an L-arginine analog, competitively inhibited NO2 release and amebicidal activity in a dose-dependent fashion, without affecting H2O2 production; however, the addition of excess L-arginine competitively restored macrophage amebicidal effects. In culture, sodium nitrite and sodium nitroprusside were cytotoxic to E. histolytica and this was reversed by the addition of myoglobin. Exogenously added FeSO4 prevented macrophage cytotoxicity. Addition of superoxide dismutase, a scavenger of O2-, partially inhibited amebicidal activity, without influencing NO2 production. Untreated and LPS-exposed macrophages produced high levels of H2O2 independent from NO2 production and amebicidal effects. However, the addition of catalase, a scavenger of H2O2, inhibited both amebicidal activity and NO2 production by activated macrophages. Our results demonstrate that NO is the major cytotoxic molecule released by activated macrophages for the in vitro cytotoxicity of E. histolytica and that O2- and H2O2 may be cofactors for the NO effector molecule.

Animals↗

PubMed1992

Nucleotide sequence of cDNA for Acacia confusa trypsin inhibitor and implication of post-translation processing.

Synthetic oligonucleotides corresponding to all possible sequences of N-terminal and C-terminal region of Acacia confusa trypsin inhibitor were used to generate ACTI-related sequences using the polymerase chain reaction on the cDNAs encoding ACTI of the seeds of legume, A. confusa. The deduced amino acid sequence agreed with that determined by the peptide analysis except an extra amino acid residue, serine, was found at the junction of A and B chain, which was removed by post-translation processing with specific protease(s). The substrate specificity of the protease(s) was found to cleave at the C-terminal sites of asparagine and serine, which was also shown to be the same case for another plant protein, abrin, isolated from legume, Abrus precatorius.

Acacia↗

PubMed1992

Clinical presentation and management of stage I cervical adenocarcinoma: a 25 year experience.

In this study, we review the clinical presentation, treatment, and prognosis of 89 patients with stage I cervical adenocarcinoma treated at Strong Memorial Hospital over the past 25 years. In the past decade, the mean age of patients with stage I cervical adenocarcinoma was 44 years, in contrast to a mean of 58 years in the prior interval (P less than 0.001). Prior to 1980 only 4% of patients were of childbearing age, whereas in the past decade 27% were under 35 years old (P = 0.02). The difference in age at presentation cannot be explained by earlier detection, as the fraction of stage I patients, the mean tumor size, and the percentage of clinically occult tumors have not changed. There were no ovarian metastases in 41 patients who underwent oophorectomy. Adenosquamous tumours did not differ in prognosis from pure adenocarcinoma. Grade and lymph node status were significant predictors of outcome. Treatment results have not improved over the past 25 years, and combined therapy with radiation and surgery offered no advantage over radiation alone. Because this tumor is more frequently seen in younger patients, the management of occult adenocarcinoma with early stromal invasion has become problematic. Ovarian conservation has been questioned, and the lack of generally accepted criteria for microinvasive adenocarcinoma has led to radical therapy in patients who might have been adequately treated with local excision. Further study is necessary to guide our recommendations regarding preservation of ovarian function or even childbearing potential in young women.

Adenocarcinoma↗

PubMed1992

Morbidity and recurrence with modifications of radical vulvectomy and groin dissection.

Vulvar carcinoma has been managed in recent years with modifications of radical vulvectomy and groin dissection. Separate groin incisions, superficial inguinal lymphadenectomy, unilateral groin dissection, and wide excision have been utilized to reduce the morbidity of treatment. In this study, the surgical management of 82 patients with vulvar squamous cell carcinoma was reviewed in order to assess morbidity and risk of recurrence. A modification of radical vulvectomy and groin dissection was employed in 67 patients, while 15 patients underwent classical en-bloc vulvar and groin dissection. Wound complications of the vulva occurred in 1 of 12 patients undergoing hemivulvectomy, in 8 of 55 undergoing radical vulvectomy, and in 7 of 15 who had en-bloc vulvar resection and groin dissection (P = 0.01). Among the 46 patients undergoing bilateral groin dissection through separate incisions, groin breakdown, lymphocyst, and lymphedema occurred in 10 (22%), 7 (15%), and 7 (15%), versus 0, 1 (7%), and 2 (13%) of the 15 who had unilateral groin dissection. Modification of vulvar resection did not increase the risk of local recurrence. Groin recurrence developed in 2 of 15 patients who underwent en-bloc groin dissection and in 1 of 46 who underwent bilateral groin dissection through separate incisions. Two of 15 who had a unilateral groin dissection recurred in the contralateral groin. The risk of recurrence as well as morbidity following modifications of radical vulvectomy with groin dissection should be considered when planning treatment.

Aged↗

PubMed1992

Inhibition of Moloney murine leukemia virus reverse transcriptase activity by tetrahydroxyxanthones isolated from the Chinese herb, Tripterospermum lanceolatum (Hyata).

Five tetrahydroxyxanthones (THXs) isolated from Tripterospermum lanceolatum (Hyata) have been shown to have a strong inhibitory effect on Moloney murine leukemia virus reverse transcriptase (Mo-MLV RT) activity when (rA)n-(dT)15 and (rC)n-(dT)12-18 were used as template-primers. 50% inhibitory concentrations of 1,3,5,6-THX, 2,3,6,7-THX 1,3,6,7-THX, 3,4,5,6-THX, and 3,4,6,7-THX were determined to be 0.15, 0.27, 0.58, 0.12, and 0.12 microM, respectively. Their effects were concentration-dependent, and the mode of inhibition was found to be by competitive inhibition with respect to template-primer. The tetrahydroxyl groups of THXs were shown to be important for their inhibitory activity. Acylation of THXs with various groups resulted in a moderate or strong decrease in their inhibitory activity.

Acylation↗

PubMed1992

Inhibitory effects of flavonoids on Moloney murine leukemia virus reverse transcriptase activity.

Several flavonoids were tested for their effects on Moloney murine leukemia virus reverse transcriptase activity. Four groups of flavonoids, namely flavones, flavanones, flavonols, and flavanonols, were studied, and it was found that flavonols and flavanonols were very active in this regard while flavones and flavanones displayed very low activity. Among the flavonoids tested, fisetin, quercetin, myricetin, kaempferol, morin, (+/-)-taxifolin, (+)-catechin, and (-)-epicatechin were shown to be highly effective in inhibiting the reverse transcriptase activity. Structure-activity relationship analysis of these flavonoids revealed that the simultaneous presence of free hydroxyl groups at positions 3 and 4' enhanced the reverse transcriptase inhibitory activity. Replacement of the 3-hydroxyl group with a monosaccharide or of the 4'-hydroxyl group with a methyl group reduced inhibitory activity. The double bond at position 2 and 3 of the flavonoid's pyrone ring is not essential for inhibiting reverse transcriptase activity. The flavonoids studied demonstrated ability to inhibit the reverse transcriptase activity using either (rA)n(dT)12-18 or (rC)n(dG)12-18 as template-primers.

DNA Polymerase I↗

PubMed1992

Inhibition of angiotensin-I-converting enzyme by tetrahydroxyxanthones isolated from Tripterospermum lanceolatum.

Five tetrahydroxyxanthones, 3,4,6,7-tetrahydroxyxanthone [1], 1,3,5,6-tetrahydroxyxanthone [2], 3,4,5,6-tetrahydroxyxanthone [3], 1,3,6,7-tetrahydroxyxanthone [4], and 2,3,6,7-tetrahydroxyxanthone [5] isolated from Tripterospermum lanceolatum inhibited angiotensin-I-converting-enzyme activity in a dose-dependent manner. The mode of inhibition of the tetrahydroxyxanthones (THXs) was found to be competitive inhibition. When the tetrahydroxy groups of THXs were blocked with acetyl groups, the angiotensin-I-converting-enzyme inhibitory activity was abolished, suggesting that the tetrahydroxy groups are indispensible for the inhibitory activity.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1992

The young pioneers: first baccalaureate nursing students in the People's Republic of China.

Nursing in the People's Republic of China, like elsewhere, has undergone monumental changes during the 20th century. This paper focuses on one of those changes by examining the professional socialization process of the first class from the first baccalaureate in nursing (BSN) programme in China since 1952. These data from this first BSN class are part of a larger study on professional socialization in which data were collected from four of the recently established 11 BSN programmes in China. To put these data into a historical context, some highlights of Chinese nursing history are noted. These will help us to understand the present-day situation in this the world's most populous nation.

Adult↗

PubMed1992

Noma neonatorum: an unusual case of noma involving a full-term neonate.

Noma neonatorum is a gangrenous process that occurs in the oral, nasal or anal area and occasionally the eyelids and scrotum of the newborn. The disease is caused by Pseudomonas aeruginosa and usually affects premature ill babies during the first few weeks of life. A full-term neonate with nasal and scrotal noma is uncommon and is therefore reported.

Humans↗

PubMed1992

[Ultrastructural observations of the anterior chamber angle tissues in congenital glaucoma].

18 trabeculectomy specimens of congenital glaucoma were examined by light and transmission electron microscopy with the finding that the primary anomalies in congenital glaucoma included the developmental defect of trabecular meshwork, excessive collagen fibrils in the trabecular matrix, shifting forward of ciliary muscle fibers, and persistent mesenchymal tissue in the chamber angle. The authors also pointed out the importance of the secondary lesions of the trabecular meshwork in the pathogenesis of congenital glaucoma.

Anterior Chamber↗

PubMed1992

Meigs syndrome with elevated serum CA 125.

Elevation of serum CA 125 levels is associated with malignant serous ovarian carcinomas and has been described in one patient with Meigs syndrome. We present two additional cases of Meigs syndrome with significant elevations in serum CA 125 and report the results of immunohistochemical staining for CA 125. CA 125 expression was localized to the omentum and peritoneal surfaces rather than the fibroma. We suggest that expression of CA 125 and accumulation of ascites in these two patients may have resulted from some common peritoneal process.

Aged↗

PubMed1992

Cellular kinetics, dosimetry, and radiobiology of alpha-particle radioimmunotherapy: induction of apoptosis.

Though clinical results for radioimmunoconjugate therapy of most common epithelial tumors have been disappointing, dramatic responses have been observed repeatedly in the treatment of high- and low-grade malignant lymphomas. This high clinical responsiveness after radioimmunoconjugate therapy sometimes appears to be out of proportion to the calculated radiation dose absorbed by the lymphoma tissue. Here we describe some key aspects of the kinetics, dosimetry, and cellular radiobiology of murine lymphoma cells exposed to 212Bi-radiolabeled alpha-particle-emitting immunoconjugates specific for the differentiation antigen Thy 1.2. Approximately 25 cell-bound alpha-particle-emitting immunoconjugates per target cell were required to reduce clonogenic survival by 90% (the radiobiological D10). Serial kinetic analyses of the antibody and radioisotope components of the immunoconjugates revealed significant levels of dechelation and up to 7.5% cellular internalization of the isotope. Cellular radiation dosimetry performed by Monte Carlo computer simulation of alpha-particle energy deposition patterns based on the observed radiopharmacokinetics showed that the D10 resulted from approximately four alpha-particle traversals through the nucleus, corresponding to an absorbed radiation dose of approximately 0.95 Gy to the cell nucleus. Electron micrographs and DNA gel studies of murine lymphoma cells undergoing radioimmunoconjugate therapy in vivo and in vitro demonstrated bizarre blebbing patterns, condensation of chromosomal material, and internucleosomal DNA fragmentation patterns characteristic of programmed cell death (apoptosis). We conjecture that the efficacy of radioimmunoconjugates against responsive cell types may be the result of passive DNA damage by ionizing radiation and the initiation of apoptosis in response to radioimmunotherapy.

Alpha Particles↗

PubMed1991

Trypsin inhibitor from the seeds of Acacia confusa.

A trypsin inhibitor (ACTI) was isolated and purified from the seeds of Acacia confusa by gel filtration, and trypsin-Sepharose 4B column affinity chromatography. The molecular weight of ACTI was found to be 21,000 +/- 1,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino acid composition analysis. ACTI contained four half-cystine and no methionine residues, and was rich in aspartic acid, glutamic acid, glycine, leucine, and lysine residues. The native trypsin inhibitor was composed of two polypeptide chains, and it inhibited trypsin and alpha-chymotrypsin stoichiometrically at the molar ratio of 1:1 and 2:1, respectively. The amino-terminal sequence analysis of the A. confusa trypsin inhibitor A and B chains revealed a more extensive homology with Acacia elata and silk tree trypsin inhibitors, and a less extensive homology with Kunitz soybean trypsin inhibitor.

Acacia↗

PubMed1991

The ability of large T antigen to complex with p53 is necessary for the increased life span and partial transformation of human cells by simian virus 40.

Simian virus 40 (SV40) T antigen binds to the tumor suppressor p53 protein, and this association may contribute to oncogenic transformation by the virus. We investigated the importance of this binding on transformation by examining three replication-competent mutants of SV40 (402DE, 402DN, and 402DH). These mutants express T antigens defective in binding to human and monkey p53s but retain some binding with mouse p53. All showed significant reduction in their ability to induce transformed cell foci of two normal human cell lines as well as a slight reduction with mouse embryo cells. Other comparable mutants which express T antigens retaining the ability to complex with p53 were able to induce foci at wild-type levels in both human and mouse cells. Further studies were performed with five T-antigen-positive clones isolated from the few human cell foci that appeared after transfection with 402 mutant DNAs. All five clones reached senescence at about the same point as did the parental untransformed cells. However, six other human cell clones obtained after transfection with DNA from nondefective mutants or wild-type virus were still growing well at more than 10 passages beyond their expected life span. These results suggest that the ability of T antigen to form stable complexes with p53 is necessary for SV40 to extend the life span and partially transform human cells in culture.

Animals↗

PubMed1991

Stable T-p53 complexes are not required for replication of simian virus 40 in culture or for enhanced phosphorylation of T antigen and p53.

We generated a number of simian virus 40 (SV40) mutants with single amino acid substitutions in T antigen between residues 388 and 411. All but one mutant (398LV) replicated like wild-type SV40 and gave rise to normal-size plaques. Three different mutations at residue 402 (Asp to Glu, Asn, or His) totally prevented the formation of stable complexes with the cellular protein p53 in monkey cells but had no effect on virus replication. Only one other mutation in this region, involving residue 401 (Met to Thr), slightly inhibited the formation of T-monkey p53 complexes. The three mutant T antigens with substitutions at residue 402 also formed no stable complexes with human p53 but generated low levels of complexes with mouse p53. These results indicate that residue 402 is critical for binding to monkey and human p53 proteins and is important for binding to mouse p53. We suggest that it is one of several points of contact. In cells infected with any one of the three residue 402 mutant viruses. T antigen and p53 became increasingly phosphorylated, as they were in cells infected with wild-type virus. Our data therefore show that stable T-p53 complexes are not required for replication of SV40 in culture or for enhanced phosphorylation of either protein.

Amino Acid Sequence↗