Biomedical subjects

J Y Lin

Publications and source records attributed to J Y Lin.

At least 91 records · Page 5Linked to original sources

PubMed1995

Effects of endogenous opioid peptides and their analogs on the activities of hypothalamic arcuate neurons in brain slices from diestrous and ovariectomized rats.

Various endogenous opioid peptides and some of their analogs were used in this study to test their effects on the membrane activities of hypothalamic arcuate neurons in brain slices. Both ovariectomized and diestrous rats were used in the study, and freshly prepared brain slices from these animals were used for extracellular single-unit recording studies. All of the opioids exhibited potent inhibitory effects on the firing of arcuate neurons, viz., beta-endorphin inhibited 55% (n = 33), DAGO 62% (n = 21), dynorphin A 55% (n = 11), U50,488 36% (n = 39), Met-enkephalin 35% (n = 54), and DPDPE 50% (n = 8) of tested arcuate neurons from ovariectomized rats. Significantly higher percentage of inhibition was observed in slice preparations from diestrous rats for DAGO 86% (n = 22), and slightly higher for dynorphin A 59% (n = 22) and U50,488 53% (n = 15). Pretreatment with naloxone prevented most of the actions by beta-endorphin and DAGO, and nor-binaltorphimine prevented those by dynorphin A and U50,488. Most of the effects of Met-enkephalin could also be blocked by nor-binaltorphimine (67%, n = 6), but less by naltrindole (25%, n = 8). Naltrindole, however, seemed to be more effective in blocking the action of [D-Pen2,5]-enkephalin (100%, n = 2). In summary, all opioids tested exerted potent inhibitory effects upon the firing of arcuate neurons possibly through multiple opioid receptors, and the presence of ovarian hormones may have an effect on the neuron's responsiveness to opioid acting on mu type receptors.

Animals↗

PubMed1995

Use of the urine-to-blood carbon dioxide tension gradient as a measurement of impaired distal tubular hydrogen ion secretion among neonates.

To evaluate the utility of the urinary-minus-blood partial pressure of carbon dioxide (U-B PCO2) gradient for the diagnosis of distal renal tubular acidosis in neonates, we measured the U-B PCO2 gradient corresponding to different urinary bicarbonate concentrations in 40 neonates. The U-B PCO2 gradient in these neonates had a significant linear relationship to the urinary bicarbonate concentration. When the urinary bicarbonate concentration was > 10 mmol/L, in all the neonates the U-B PCO2 could be increased above the 20 mm Hg level. We conclude that it is appropriate to determine the U-B PCO2 gradient as an index of distal urinary acidification and that it is a necessary test for diagnosis of distal renal tubular acidosis in neonates.

Acidosis, Renal Tubular↗

PubMed1995

Amino acid sequences of trypsin inhibitors from the melon Cucumis melo.

Two squash family trypsin inhibitors, CMeTI-A and CMeTI-B, were isolated from the melon (Cucumis melo) seeds, by ion exchange chromatography, gel filtration, affinity chromatography, and high-performance liquid chromatography, and their amino acid sequences were determined. All inhibitors contain 29 amino acid residues including 6 half-cystine residues. They differ by twelve amino acid residues. These polypeptides are strong inhibitors of bovine trypsin, with Ki values of 1.6 x 10(-10) M (CMeTI-A) and 4.7 x 10(-10) M (CMeTI-B). The products of CMeTI-A and CMeTI-B cleaved at their reactive sites by tryptic digestion during the purification by trypsin-Sepharose 4B affinity column chromatography are active against trypsin activity, but a molar ratio of inhibitor to trypsin of 2:1 for trypsin-treated CMeTI-B or 1:1 for trypsin-treated CMeTI-A is required.

Amino Acid Sequence↗

PubMed1995

Home care for the urban chronically ill elderly in the People's Republic of China.

This study examines the home care situation of seventy-five urban chronically ill men and women and their caregivers in three cities in the People's Republic of China. It documents the type of home care provided, the severity of illness, and the dependency in activities of daily living in order to appreciate the complexity of these care situations. The findings reveal that women serve as the caregivers in the majority of the cases and often they are elderly spouses with health problems of their own. The physical, social, psychological, and financial problems experienced by these patients create an enormous burden for the caregivers whether spouses or younger family members coming home from work to a second shift. If alternatives to home care, such as nursing homes, were available, 54 percent of these caregivers would be willing to institutionalize their elderly relative. All caregivers express the need for more assistance in providing home care. This study raises questions regarding the role of the family, the state, and specifically the health care system in caring for the elderly chronically ill in light of their increasing numbers in the population.

Activities of Daily Living↗

PubMed1995

Transforming growth factor-beta 1 primes macrophages for enhanced expression of the nitric oxide synthase gene for nitric oxide-dependent cytotoxicity against Entamoeba histolytica.

Nitric oxide (NO) produced by activated macrophages is the major cytotoxic molecule for in vitro cytotoxicity against Entamoeba histolytica trophozoites. Transforming growth factor-beta 1 (TGF-beta 1) is a potent negative regulator of several macrophage functions, including NO production. In this study, we investigated the effect of TGF-beta 1 on macrophage nitric oxide synthase (mac-NOS) mRNA expression and NO production for macrophage cytotoxicity against E. histolytica trophozoites. TGF-beta 1 by itself was incapable of inducing mouse bone marrow-derived macrophage (BMM) amoebicidal activity and NO production (as measured by nitrite). In contrast, TGF-beta 1 pretreatment (4 hr) primed BMM for an enhanced amoebicidal activity of 15% and 23% in response to (interferon-gamma) IFN-gamma+tumour necrosis factor-alpha (TNF-alpha) or IFN-gamma+lipopolysaccharide LPS, concomitant with increased NO production of 85% and 27%, respectively. TGF-beta 1 pretreatment increased NO production in response to IFN-gamma+TNF-alpha/LPS stimulation in a time- and dose-dependent manner. By Northern blot analysis, the increased NO production of TGF-beta 1-pretreated BMM was preceded by markedly enhanced expression of mac-NOS mRNA. The priming effect of TGF-beta 1 on NO production was critically dependent on both a TNF-alpha (> or = 100 U) and a LPS (> or = 100 ng) triggering dose in the presence of IFN-gamma. TGF-beta 1 pretreatment enhanced TNF-alpha mRNA expression, but had no effect on TNF-alpha production in culture supernatants after 4 hr of stimulation with IFN-gamma+TNF-alpha/LPS; however, at a later time-point (16-48 hr), even though the levels of TNF-alpha mRNA expression were unaffected, TNF-alpha production was reduced. These data demonstrate that TGF-beta 1 priming for increased mac-NOS mRNA expression for NO-dependent cytotoxicity against E. histolytica in response to IFN-gamma+TNF-alpha/LPS stimulation may be involved in the modulation of a TNF-alpha triggering signal by TGF-beta 1.

Animals↗

PubMed1994

Inactivation of Acacia confusa trypsin inhibitor by site-specific mutagenesis.

Native Acacia confusa trypsin inhibitor (ACTI) contains two disulphide bonds; one is an intrachain disulphide bond (Cys40-Cys86), located in the A-chain, while the other is an interchain disulphide bond (Cys133-Cys141) connecting the A- and B-chain; the inhibitor consists of 175 amino acid residues, 136 residues in the A-chain and 39 residues in the B-chain. The putative reactive site of ACTI is located at Lys64, while for all other Kunitz family trypsin inhibitors it is at Arg64. When the Lys64 residue of ACTI was converted into Ile or Arg by site-specific mutagenesis, the K64I mutant completely lost its inhibitory activity but the K64R mutant retained most of its inhibitory activity. The C133G mutant lost its inhibitory activity while the C40G mutant did not. This suggests that the interchain disulphide bond (Cys133-Cys141) linking two beta-strands of the six-strand beta-barrel is essential for ACTI inhibitory activity, while the intrachain disulphide bond (Cys40-Cys86) connecting the two loops is non-essential.

Acacia↗

PubMed1994

Fluorescent spot test method for specific detection of beta-lactamases.

A simple, sensitive fluorescent spot test method for specific detection of microbial beta-lactamases has been developed, based on the modification of a previously disclosed method (K. C. S. Chen, October 23, 1990, U.S. Patent 4,965,193). The new fluorescence developer used in the present study consisted of 0.5 mM HgCl2, in 0.5 M sodium citrate buffer, pH 4.5, prepared in 0.5% formaldehyde aqueous solution. A beta-lactam substrate solution consisting of a beta-lactam antibiotic with an acyl side chain containing an alpha-amino group and an alpha-phenyl group, or its derivatives, was incubated with a beta-lactamase-producing organism. One volume of the fluorescence developer was added to 4 vol of the incubated beta-lactam substrate solution, followed by heating the mixture at 45 degrees C for 10 min. The mixture was spotted on filter paper. Production of fluorophore indicated beta-lactamase activity. Each fluorophore was analyzed by TLC and its chemical identity was determined. Using ampicillin as the penicillinase substrate and cephalexin as the cephalosporinase substrate, the new method can be conveniently carried out by using dropping bottles for storing and dispensing the substrate solutions and the fluorescence developer. This modified method also provided more favorable conditions for the penicillinases to remain active during fluorescence development. Therefore, the sensitivity of the test was increased.

Ampicillin↗

PubMed1994

A new crystal form of abrin-a from the seeds of Abrus precatorius.

A new crystal form of abrin-a from the seeds of Abrus precatorius has been obtained by vapor diffusion method. The abrin-a crystals belong to monoclinic space group P2(1) with cell dimensions a = 84.58 A, b = 73.07 A, c = 48.23 A, beta = 96.20 degrees. An asymmetric unit contains one protein molecule of molecular weight 65 kDa and has a solvent content of approximately 46%.

Abrin↗

PubMed1994

Cloning and expression of three abrin A-chains and their mutants derived by site-specific mutagenesis in Escherichia coli.

DNAs encoding of three abrin A-chains were obtained from the cDNA library of Abrus precatorius by polymerase chain reaction and ligated into the expression vector, pGEX-2T. The mature A-chains of abrins a, b and d have been expressed in the cytoplasm of Escherichia coli, and the yield of the soluble recombinant proteins was 7 mg/l induced culture. Three recombinant abrin A-chains were purified to be homogeneity and their N-glycosidase ability to inhibit protein biosynthesis in a cell-free system and to depurinate 28S rRNA in rat liver ribosomes was demonstrated in vitro. The recombinant abrin-a A-chain had the highest N-glycosidase activity among three recombinant abrin A-chains while the recombinant abrin-b A-chain, the least. Three mutants, glutamic-acid-to-alanine replacement (E164A), arginine to leucine (R167L) or double mutation (E164A and R167L) were constructed and expressed. The protein-biosynthesis-inhibitory activity of mutant (E164A), mutant (R167L) and the double mutant was found to be 25-fold, 625-fold and 1250-fold lower than that of wild type, respectively. The results indicated that Arg167 was essential for abrin toxin A-chain catalysis.

Abrin↗

PubMed1994

Cytokine production by cells in cerebrospinal fluid during experimental allergic encephalomyelitis in SJL/J mice.

Cytokine production by T cells in the cerebrospinal fluid (CSF) and central nervous system (CNS) of SJL/J mice during myelin basic protein (MBP)-induced experimental allergic encephalomyelitis (EAE) was examined. Reverse transcriptase/polymerase chain reaction (RT/PCR) was used to measure interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) mRNA levels from perfused CNS tissue (brain and spinal cord) and from cells isolated from CSF. Animals were grouped according to EAE severity, ranging from asymptomatic (adjuvant only) to severe disease (paralysis or severe paresis). Cytokine signals, normalized to actin, were almost undetectable in control tissues, and only slightly elevated in whole CNS tissue from animals with mild EAE. Both cytokine messages were strongly upregulated in CNS tissues derived from severely affected animals, consistent with previous observations correlating disease progression with infiltration by memory/effector CD4+ T cells, the major source of these cytokines. This cytokine upregulation was specific to the CNS, since other organs from the same animals did not express significant levels of IL-2 and IFN-gamma. CSF was obtained from the cisterna magna of unperfused mice and verified as such by absence of red blood cells (RBCs) and by immunoglobulin concentration orders of magnitude lower than in serum. Cytokine message was measured in RNA isolated from cells in CSF. Levels of IL-2 and IFN-gamma mRNA in CSF cells were significantly elevated in mild EAE and strongly upregulated in severe disease, correlating with those in total CNS tissue. These results confirm the CSF as representative of the immune status of the CNS and indicate a role for IL-2 and IFN-gamma in inflammatory CNS disease.

Animals↗

PubMed1994

Stimulatory effects of bombesin-like peptides on hypothalamic arcuate neurons in rat brain slices.

The effects of bombesin, gastrin-releasing peptide, neuromedin C, ranatensin, and neuromedin B on hypothalamic arcuate neurons were tested in this study using extracellular single-unit recording in fresh brain tissue slices. Adult ovariectomized Sprague-Dawley rats were used for preparation of brain slices. All bombesin-like peptides in pmol ranges exhibited potent stimulatory effects on the firing of arcuate neurons, i.e., gastrin-releasing peptide stimulated 90.9% (n = 22), bombesin 78.0% (n = 41), neuromedin C 63.2% (n = 19), ranatensin 58.0% (n = 22), and neuromedin B 50.0% (n = 6) of arcuate neurons tested. Pretreatments with either [Leu13-psi(CH2NH)-Leu14]-bombesin or [D-Phe6,Des-Met14]-bombesin6-14 ethylamide, two bombesin antagonists, significantly blocked most of the actions of bombesin-like peptides tested. The present results further support the notion that bombesin-like peptides may play a significant role in the arcuate nucleus.

Animals↗

PubMed1994

Early detection of unilateral occlusion of duplicated müllerian ducts: the use of serial pelvic sonography for girls with renal agenesis.

For early detection of unilateral occlusion of duplicated müllerian ducts, serial pelvic sonography was performed in 215 girls with known renal agenesis, especially following menarche, during the last 6 years. To date, 16 girls with unilateral occlusion of duplicated müllerian ducts were detected. We stress the value of this modality, which can lead to a prompt diagnosis, and allow for early and appropriate surgical intervention.

Abnormalities, Multiple↗

PubMed1994

Tumor necrosis factor alpha augments nitric oxide-dependent macrophage cytotoxicity against Entamoeba histolytica by enhanced expression of the nitric oxide synthase gene.

Nitric oxide (NO measured as nitrite, NO2-) is the major effector molecule produced by activated macrophages for in vitro cytotoxicity against Entamoeba histolytica trophozoites. In this study, we determine whether tumor necrosis factor alpha (TNF-alpha) produced by activated bone marrow-derived macrophages (BMM) is involved in the induction of the inducible NO synthase gene (mac-NOS) for NO-dependent amebicidal activity. TNF-alpha alone did not directly induce macrophage NO2- production to kill amebae; however, in combination with increasing concentrations of TNF-alpha and gamma interferon (IFN-gamma), BMM amebicidal activity and NO2- production progressively increased and showed a significant linear correlation. Antiserum to TNF-alpha and the NO synthase inhibitor NG-monomethyl L-arginine (L-NMMA) inhibited the synergistic effects of TNF-alpha and IFN-gamma. BMM activated with increasing concentrations of lipopolysaccharide (LPS) and IFN-gamma showed a significant linear correlation between TNF-alpha release and NO2- production. Antiserum to TNF-alpha suppressed TNF-alpha release, NO2- production, and amebicidal activity by 93, 53, and 86%, respectively. L-NMMA diminished NO2- production by 74% and macrophage amebicidal activity by 83% but had no effect on TNF-alpha release. Quantification by Northern (RNA) blot analyses demonstrated that IFN-gamma in combination with TNF-alpha or LPS increased markedly the accumulation of mac-NOS and TNF-alpha mRNAs in a time-dependent manner with a concomitant increase in NO and TNF-alpha production. Peak induction of mac-NOS occurred after 24 h, whereas TNF-alpha mRNA was rapidly expressed after 4 h and remained stable for 48 h. Taken together, these data argue that TNF-alpha augments NO-dependent macrophage cytotoxicity against E. histolytica via elevated levels of mac-NOS mRNA expression which may be associated with the accumulation of TNF-alpha mRNA.

Amino Acid Oxidoreductases↗

PubMed1994

Ethical reasoning concerning the feeding of severely demented patients: an international perspective.

Structured interviews were held with 149 registered nurses in seven countries in America, Asia, Australia and Europe concerning the feeding of severely demented patients who do not accept food. The most common reasons for nurses being willing to change their decision to feed or not to feed were an order from the medical head, a request from the patient's husband and/or the staff meeting. There was a connection between the willingness to feed and the ranking of ethical principles. Nurses who were most prone to feed the patient most often gave a high rank to the ethical principle of sanctity of life, while those who primarily chose not to feed the patient gave a high rank to the ethical principle of autonomy. All nurses stressed the ethical principle of beneficence.

Adult↗

PubMed1993

Effects of systemic administration of 6-hydroxydopamine, 6-hydroxydopa and 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine (MPTP) on tuberoinfundibular dopaminergic neurons in the rat.

Using systemic route of administration, the effects of several neurotoxins on hypothalamic tuberoinfundibular dopaminergic neurons were focused in this study. 6-Hydroxydopamine (6-OHDA, 10 or 100 mg/kg b.wt., i.v. or ip) produced a dose (37 vs. 50%)- and time (41 to 29% from day 4 to day 9)-dependent depletion of hypothalamic median eminence dopamine concentrations, and increases of serum prolactin levels in ovariectomized rats. Other central dopaminergic neurons, however, were not significantly affected. Similar treatments with 6-hydroxydopa (6-OHDOPA) were less effective. On the other hand, treatments of 1-methyl-4-phenyl-1,2,3,6-tetrahydroxypyridine (MPTP, 10 mg/kg b.wt./day, ip) for 7 or 14 days produced significant decreases of dihydroxyphenylacetic acid (DOPAC) levels in the median eminence and periventricular regions, and increases in serum prolactin levels. Other central dopaminergic neurons were not significantly affected, though. These results suggest that systemic administration of 6-OHDA, 6-OHDOPA, or MPTP, can produce specific destructive effects on the tuberoinfundibular dopaminergic neurons.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1993

Cloning and expression of the gene encoding Acacia confusa trypsin inhibitor that is active without post-translational proteolysis.

A recombinant plasmid containing the coding regions for Acacia confusa trypsin inhibitor (ACTI) has been constructed and expressed in Escherichia coli cells, as a fusion protein between ACTI and glutathione S-transferase (GST). The GST-fusion was produced as a soluble protein which did not require denaturing agents such as urea to solubilize it. The recombinant ACTI (reACTI) was obtained by treating the GST-fusion protein with thrombin. Both the reACTI and fusion protein have a strong inhibitory effect on trypsin activity without post-translational proteolysis.

Acacia↗

PubMed1993

Primary structure of three distinct isoabrins determined by cDNA sequencing. Conservation and significance.

A family of toxic proteins, the isoabrins, which possess N-glycosylase activity toward eukaryotic 28 S r-RNA, may have potential use in cancer chemotherapy. By polymerase chain reaction techniques, cDNA clones of three isoabrins, carrying A and B-chain sequences, were isolated and their nucleotide sequences were determined. The isoabrins consist of an A-chain comprised of 250 of 251 amino acids, followed by a 10 amino acid linker and a B-chain of 267 amino acids. There is substantial conservation in the B-chain of the three isoabrins, with less than six amino acid substitutions, whereas as many as 46 amino acid substitutions occur in the A-chains. Based on the relationships between the biological activities and the putative amino acid sequences of the isoabrins, three isoabrins, abrin-a, -b and -d, could be identified and the potential epitope of immunological response of these isoabrins could be assigned.

Abrin↗

PubMed1993

An international perspective of active euthanasia: attitudes of nurses in seven countries.

This exploratory study examines the ethical justification that cancer care and dementia care nurses gave for active voluntary euthanasia. A convenient sample of 319 nurses working in seven countries was interviewed using a structured interview guide. The great majority of the nurses could not ethically justify active voluntary euthanasia. Even if the law changed, only 96 of the total sample viewed active voluntary euthanasia as ethical. For those nurses who could ethically justify active voluntary euthanasia, the majority did so because of the patients' suffering.

Adult↗