Biomedical subjects

J H Lin

Publications and source records attributed to J H Lin.

At least 253 records · Page 14Linked to original sources

PubMed1993

Direct visualization of the transposed ABL gene in a duplicated masked Ph chromosome.

In a small percentage of cases of chronic myelogenous leukemia (CML), where the Ph chromosome is masked because of highly complex translocations and sub-microscopic rearrangements, precise identification of chromosomal aberrations by routine banding techniques has been difficult. We report on a new case of CML in which a single copy of a masked Ph chromosome was duplicated during blast crisis, i.e., the karyotype was 47,XY,dir ins(22;9)(q11;q34.1q34.2),t(1;22) (q21;q11), + der (22)t(1;22)(q21;q11). The chromosome in situ suppression hybridization (CISS) technique with whole chromosome 1 and 22 specific painting probes demonstrated that 22q11-qter had been translocated to 1q21, whereas 22q11 was the recipient of 1q21-qter. Furthermore, a cosmid probe identified the location of the ABL gene on only one chromosome 9 (band q34). The other ABL gene could be detected on both derivative chromosomes 22 at band q11 which was flanked by the translocated part of the long arm of chromosome 1, thus providing direct visualization of the ABL insertion in a double masked Ph chromosome. A breakpoint within the 5.8 kb major breakpoint cluster [M-BCR] region was shown by Southern blotting.

Adult↗

PubMed1993

Chromosomal localization of uroplakin genes of cattle and mice.

The asymmetric unit membrane (AUM) of the apical surface of mammalian urinary bladder epithelium contains several major integral membrane proteins, including uroplakins IA and IB (both 27 kDa), II (15 kDa), and III (47 kDa). These proteins are synthesized only in terminally differentiated bladder epithelial cells. They are encoded by separate genes and, except for uroplakins IA and IB, appear to be unrelated in their amino acid sequences. The genes encoding these uroplakins were mapped to chromosomes of cattle through their segregation in a panel of bovine x rodent somatic cell hybrids. Genes for uroplakins IA, IB, and II were mapped to bovine (BTA) Chromosomes (Chrs) 18 (UPK1A), 1 (UPK1B), and 15 (UPK2), respectively. Two bovine genomic DNA sequences reactive with a uroplakin III cDNA probe were identified and mapped to BTA 6 (UPK3A) and 5 (UPK3B). We have also mapped genes for uroplakins IA and II in mice, to the proximal regions of mouse Chr 7 (Upk1a) and 9 (Upk2), respectively, by analyzing the inheritance of restriction fragment length variants in recombinant inbred mouse strains. These assignments are consistent with linkage relationships known to be conserved between cattle and mice. The mouse genes for uroplakins IB and III were not mapped because the mouse genomic DNA fragments reactive with each probe were invariant among the inbred strains tested. Although the stoichiometry of AUM proteins is nearly constant, the fact that the uroplakin genes are unlinked indicates that their expression must be independently regulated. Our results also suggest likely positions for two human uroplakin genes and should facilitate further analysis of their possible involvement in disease.

Animals↗

PubMed1993

Long-term enhancement of EPSP and NMDA receptor-mediated synaptic transmission in the amygdala.

An in vitro slice preparation of rat amygdala was used to study the long-term modifications of synaptic efficacy following high-frequency stimulation of the ventral endopyriform nucleus. Delivery of brief tetani to the afferent fibers led to a long-term potentiation (LTP) of the amplitude and the initial slope of excitatory postsynaptic potential (EPSP). Pretreatment the slices with DL-2-amino-5-phosphonovaleate (DL-APV, 50 microM) blocked the induction of LTP, indicating that N-methyl-D-aspartate (NMDA) receptor activation is required for induction. NMDA receptor-mediated component of synaptic response (EPSPNMDA) was isolated by application of a solution containing 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX, 10 microM) and bicuculline (20 microM). Tetanic stimulation led to a lasting potentiation of the EPSPNMDA. These results suggest that brief repetitive stimulation of afferent pathway produces forms of LTP that share many properties of LTP seen in the CA1 region of the hippocampus.

2-Amino-5-phosphonovalerate↗

PubMed1993

The gastrin-receptor antagonist L-365,260 inhibits stimulated acid secretion in humans.

We investigated the effect of a novel gastrin-cholecystokinin-B receptor antagonist, L-365,260 [(3R)-3(N'-3-methylphenyl)ureido)-1,3-dihydro-5-phenyl- 2H-1,4-benzodiazepin-2-one], on gastric acid secretion in humans. In a double-blind, four-period crossover study, eight subjects received single oral doses of placebo or of 2.5, 10, or 50 mg L-365,260, followed by an intravenous infusion of pentagastrin at doses of 0.05, 0.4, and 2 micrograms/kg/hr for successive 30-minute periods. L-365,260 caused a dose-dependent inhibition of pentagastrin-stimulated gastric acid secretion. A single oral dose of 50 mg L-365,260 produced 50% inhibition of the gastric acid output response to pentagastrin (0.4 micrograms/kg/hr) when the mean (+/- SD) plasma L-365,260 concentration was 502 +/- 108 ng/ml. Plasma L-365,260 concentrations (all doses combined) and the inhibition of gastric acid output were correlated with a correlation coefficient of r = 0.45 (p < 0.05). Single oral doses of L-365,260 up to 50 mg did not inhibit basal gastric acid output or alter plasma gastrin concentrations. L-365,260 was well tolerated at oral doses up to 50 mg. These findings show that L-365,260 is an orally active antagonist at gastrin-cholecystokinin-B receptors in humans.

Adolescent↗

PubMed1993

RNA-binding activity of hepatitis delta antigen involves two arginine-rich motifs and is required for hepatitis delta virus RNA replication.

Hepatitis delta antigen (HDAg) is an RNA-binding protein with binding specificity for hepatitis delta virus (HDV) RNA (J. H. Lin, M. F. Chang, S. C. Baker, S. Govindarajan, and M. M. C. Lai, J. Virol. 64:4051-4058, 1990). By amino acid sequence homology search, we have identified within its RNA-binding domain two stretches of an arginine-rich motif (ARM), which is present in many prokaryotic and eukaryotic RNA-binding proteins. The first one is KERQDHRRRKA and the second is EDEKRERRIAG, and they are separated by 29 amino acids. Deletion of either one of these ARM sequences resulted in the total loss of the in vitro RNA-binding activity of HDAg. Thus, HDAg is different from other RNA-binding proteins in that it requires two ARM-like sequences for its RNA-binding activity. Replacement of the spacer sequence between the two ARMs with a shorter stretch of sequence also reduced RNA binding in vitro. Furthermore, site-specific mutations of the basic amino acid residues in both ARMs resulted in the total loss or reduction of RNA-binding activity. The biological significance of the RNA-binding activity was studied by examining the trans-activating activity of the RNA-binding mutants. The plasmids expressing HDAgs with various mutations in the RNA-binding motifs were cotransfected with a replication-defective HDV dimer cDNA construct into COS cells. It was found that all the HDAg mutants which had lost the in vitro RNA-binding activity also lost the ability to complement the defect of HDV RNA replication. We conclude that the trans-activating function of HDAg requires its binding to HDV RNA.

Amino Acid Sequence↗

PubMed1993

Analysis of carbamazepine's anticonvulsant actions in hippocampal and amygdaloid slices of the rat.

The mechanism of action of the anticonvulsant drug carbamazepine was studied in rat hippocampal and amygdaloid slices using intracellular recording techniques. Stimulation of the Schaffer collateral/commissural pathway evoked an excitatory postsynaptic potential (EPSP) in CA1 pyramidal cells. Thirty minutes after superfusing with Mg(++)-free solution, the same stimulus intensity triggered burst firing. Application of carbamazepine reversibly reduced the burst duration in a dose-dependent manner. Synaptic response mediated by the N-methyl-D-aspartate (NMDA) receptors (EPSPNMDA) was isolated pharmacologically by application of a solution containing non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX,10 microM) and gamma-aminobutyric acidA receptor or antagonist picrotoxin (50 microM). Carbamazepine reversibly blocked the amplitude of EPSPNMDA in a concentration which did not affect the normal synaptic transmission. These results suggest that the combined blockade of NMDA receptors and firing of action potential forms the basis for the anticonvulsant effect of carbamazepine.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1993

[Previously deposited autologous blood for rheumatic patient in surgical field].

From June 1991 to February 1992, an autologous blood transfusion program was employed for 26 rheumatic patients in this hospital. Among them, 16 were diagnosed as rheumatoid arthritis (RA), 6 osteoarthritis (OA) and 4 ankylosing spondylitis (AS). Knee synovectomy was performed for 7 patients and total hip or knee arthroplasty for the other 19 patients. The total amount of blood autotransfused was 15,200 ml, which accounted for 89.4% of the total blood transfusion during the operation. Twenty-one patients (80.7%) received only autologous blood, while the other 5 (19.3%) required additional homologous blood. Only one adverse reaction occurred in one patient who received homologous blood. By the observation of a series of clinical and immunological indices, no aggravation was seen. Therefore we believe a program of prior deposit and storage of autologous blood for rheumatic patients, who need surgical treatment, is both cost-effective and safe.

Adult↗

PubMed1993

Anticonvulsant effects of dizocilpine against picrotoxin-induced seizure activity in vivo and in vitro.

The effects of dizocilpine on picrotoxin (PTX)-induced generalized tonic-clonic (GTC) seizures in vivo and PTX-induced epileptiform activity in vitro brain slices were studied. Groups of rats were pretreated intraperitoneally with dizocilpine or a control saline vehicle. Twenty minutes later, subgroups within each pretreatment group were injected subcutaneously with different doses of PTX. The results showed that dizocilpine significantly increases the mean latency period from administration to GTC seizures and reduces the incidence of death. Intracellular recording techniques were used to examine the mechanism underlying the anticonvulsant action of dizocilpine on the amygdala. A superfusion of dizocilpine reduced the evoked burst duration by an average of 35%. The synaptic response, mediated by the N-methyl-D-aspartate (NMDA) receptor, was isolated by application of a solution containing the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and GABAA blocker PTX. A superfusion of dizocilpine blocked NMDA receptor-mediated synaptic excitation. These results suggest that the anticonvulsant effect of dizocilpine is likely due to its blocking action on the NMDA receptors.

Animals↗

PubMed1993

Role of calcium in plasma protein binding and renal handling of alendronate in hypo- and hypercalcemic rats.

Alendronate (4-amino-1-hydroxybutylidine-1,1-bisphosphonate), an antiosteolytic agent, is currently under investigation for the treatment of osteoporosis. Earlier studies in animals from this laboratory disclosed that systemically administered alendronate is rapidly taken up by bone tissues to the extent of 60% to 70% of the dose and excreted by the kidney, 30% to 40% in 24 hr, and that renal excretion is the only route of elimination. This study was designed to explore the effect of calcium on plasma protein binding and the renal handling of alendronate. The binding of alendronate to rat plasma was concentration, pH and calcium dependent. The fraction of unbound drug in rat plasma increased from about 3% to 9% over a drug concentration range of 0.2 to 10 micrograms/ml. Supplementation of calcium strongly augmented the binding to serum albumin. The binding of alendronate in plasma increased with increasing pH from about 50% at pH 6.6 to 98% at pH 8.6. The effects of pH on the binding of calcium and of alendronate to serum albumin were qualitatively similar. Under steady-state conditions, the binding of alendronate was substantially lower in hypocalcemic rats but unchanged in hypercalcemic rats. Although hypocalcemia caused a significant decrease in the renal secretion of alendronate, there was no effect on the renal secretion of tetraethylammonium bromide and p-aminohippuric acid. The differential effect of hypocalcemia suggests that calcium may play an important role in the renal handling of alendronate. However, hypercalcemia resulted in a substantial decrease of renal secretion of all three compounds and the decreased renal secretion was associated with a marked decrease in the glomerular filtration rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Alendronate↗

PubMed1993

Grip strength: relationship to shoulder position in normal subjects.

The objective of this study was to evaluate the effect of shoulder position on grip strength. A Jamar dynamometer was used to measure the grip strength of 160 subjects (80 males and 80 females), stratified on both sex and age, in the four testing positions. For each of the tests of grip strength, the subject stood with the shoulder adducted and neutrally rotated while the forearm and wrist were held in the neutral position. The four hand strength tests consisted of three positions in which the elbow was maintained in full extension combined with varying degrees of shoulder flexion (i.e., 0 degree, 90 degrees, and 180 degrees) and of one position in which the elbow was flexed at 90 degrees with the shoulder in 0 degree of flexion. Only the dominant hand was tested. The results showed that the highest mean grip strength measurement was recorded when the shoulder was positioned at 180 degrees of flexion with elbow in full extension; whereas the position of 90 degrees elbow flexion with shoulder in 0 degree of flexion had the lowest grip strength score. In addition, the grip strength measured with the elbow in extension, regardless of shoulder position (i.e., 0 degree, 90 degrees, and 180 degrees of flexion), was significantly higher than when the elbow was flexed at 90 degrees with the shoulder positioned at 0 degree of flexion. Finally, grip strength differed significantly for both sexes and for each age group. The findings are valuable in the evaluation and rehabilitation training of hand injured patients.

Adult↗

PubMed1992

Sustained enhancement of NMDA receptor-mediated synaptic potential by isoproterenol in rat amygdalar slices.

The effect of isoproterenol (Iso) on synaptic transmission mediated by the N-methyl-D-aspartate (NMDA) receptors (EPSPNMDA) was investigated in slices of rat amygdala using intracellular recording techniques. EPSPNMDA was isolated pharmacologically by application of a solution containing the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 microM) and GABAA receptor blocker bicuculline (20 microM). Superfusion of Iso (15 microM) produced a long-lasting enhancement of EPSPNMDA. Pretreatment the slices with propranolol (10 microM) completely prevented the effect of Iso confirming the mediation by beta-adrenergic receptors. These results provide the direct evidence for adrenergic modulation of excitatory amino acid neurotransmission in the vertebrate central nervous system.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1992

Quantitation of a new cholecystokinin and gastrin receptor antagonist (L-365,260) in dog and rat plasma by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) procedure has been developed for the quantification of L-365,260 (I), a cholecystokinin and gastrin receptor antagonist, in dog and rat plasma. The method involves liquid-liquid extraction and HPLC with ultraviolet detection. Standard curves were linear over the range 7.5-2000 ng/ml for rat and dog plasma. The method is reproducible and reliable with a detection limit of 7.5 ng/ml in biological fluids. The mean coefficients of variation for concentrations within the range of the standard curve range were 3.84 and 2.56%, respectively, for intra-day analysis and 4.48 and 4.26%, respectively, for inter-day analysis. Application of the development was successfully demonstrated by quantifying the concentration of I in both dog and rat plasma samples following an intravenous or oral dose of 5 mg/kg I.

Animals↗

PubMed1992

Distinction between supercoiled and linear DNA in transverse agarose pore gradient gel electrophoresis.

Four species of linear DNA and the first four members of a linking series, generated by treatment of plasmid DNA (PUC19, 2.7 kb) with mitochondrial topoisomerase I, were differentiated by transverse agarose pore gradient gel electrophoresis. The experimental curves of migration distance vs. agarose concentration (Ferguson curves) of supercoiled DNA exhibit a steeper trajectory than those of linear DNA of the same size range. As a consequence, the four supercoiled species exhibit an increase in apparent size (relative to linear DNA standards) with increasing agarose concentration. Both the crossing of the Ferguson curves with those of linear standards as well as the apparent size increase with agarose concentration can serve to detect supercoiled plasmid-sized DNA in mixtures with linear DNA.

DNA↗

PubMed1992

DNA topoisomerase I from calf thymus mitochondria is associated with a DNA binding, inner membrane protein.

During purification of the type I DNA topoisomerase from calf thymus mitochondria, two polypeptides, p78 and p63, cofractionate with the enzymatic activity (Lazarus et al., (1987) Biochemistry 26, 6195-6203). The two polypeptides are released from a mitochondrial inner membrane preparation by nonionic detergent lysis and both adsorb strongly to a single-stranded DNA agarose column. We have attempted to characterize the relationship between these two polypeptides and have found the following: (i) the mitochondrial topoisomerase is active in free (monomer) and associated (heterodimer) form; (ii) the catalytic activity resides solely in p78, as adjudged by both the covalent linkage of the enzyme to substrate DNA and the ability of the enzyme to relax supercoils; (iii) at low ionic strength the enzyme is active in monomer form with p78 alone being sufficient for activity; (iv) in high salt, the high molecular weight species is a 140-kDa heterodimer composed of one p78 and one p63; and (v) the two polypeptides are not structurally related as digestion with V8 protease results in distinct proteolytic fragment patterns. These results suggest that p63 may have an important role in the metabolism of the mitochondrial topoisomerase.

Animals↗

PubMed1992

Cortisol content of eggs and larvae of teleosts.

The whole-animal content of the cortisol was measured in embryos and larvae of tilapia (Oreochromis mossambicus), rainbow trout (Oncorhynchus mykiss), ayu (Plecoglossus altivelis), milkfish (Chanos chanos), and yellowfin bream (Acanthropagrus latus) by radioimmunoassay following the validation of an extraction method. The total cortisol content in tilapia was 50.3 +/- 19.1 pg immediately following fertilization, then decreased abruptly and maintained a lower level of 10-17 pg until larval hatching; after hatching the cortisol content increased to 47.2 +/- 11.9 pg by the seventh day. Newly hatched rainbow trout had 60.3 +/- 6.4 pg cortisol and then increased their cortisol level slowly to 83.0 +/- 7.2 pg by the fifth day after hatching. Ayu larvae contained 5.2 pg cortisol immediately following hatching. On the other hand, pelagic milkfish revealed a much lower cortisol level, being undetectable from hatching until the second day and ranging from 0.4 to 3.7 pg from the third to seventh day after hatching. Yellowfin bream, demonstrating a similarity to milkfish, were not found to have any detectable cortisol from hatching until the third day, but presented 1.6-7.7 pg from the fifth to seventh day after hatching. The presence and clearance of cortisol during early development of fertilized eggs of tilapia suggest a maternal origin of the hormone. The amount of cortisol deposited in the larval body of tilapia increased after hatching from 25% to nearly 100% of the total cortisol in whole larvae, while that in the larval yolk sac decreased to an undetectable level, implying that the increased cortisol may be produced or secreted by the larva. The possible role of cortisol in larval development is discussed.

Animals↗

PubMed1992

Uptake and stereoselective binding of the enantiomers of MK-927, a potent carbonic anhydrase inhibitor, by human erythrocytes in vitro.

MK-927 [5,6-dihydro-4H-4(isobutylamino)thieno(2,3-B)thiopyran -2-sulfonamide-7.7 dioxide], a potent carbonic anhydrase inhibitor, contains a chiral center and exists as a racemate. In order to understand the kinetic behavior of the enantiomers of MK-927 in the body, the uptake and binding of these compounds were studied in human erythrocytes in vitro. Since no degradation or metabolism of the enantiomers occurred during incubation in blood, one can describe the equilibration of the drugs between plasma and erythrocytes by a closed two-compartment system. Erythrocytes were considered as a compartment composed of two parts: one in which free drug is exchangeable to plasma and the other in which drug is tightly bound to carbonic anhydrase in a Michaelis-Menten type binding. After the addition of the enantiomers individually to fresh blood, they were taken up by erythrocytes rapidly in a concentration-dependent manner. The time to achieve equilibrium decreased as the concentration increased, suggesting saturation of binding sites. With the assumption of simple diffusion, the binding and transfer kinetics were determined simultaneously by computer fitting. There were no stereoselective differences in the transfer process of the enantiomers across the erythrocyte membrane, while binding of the enantiomers exhibited stereoselectivity. The penetration of the unbound enantiomer across the erythrocyte cell membrane was rapid, with a mean transit time of about 3 sec. The S-(+)-enantiomer was bound to the high-affinity carbonic anhydrase isoenzyme more strongly than the R-(-)-enantiomer by approximately 10-fold. For the low-affinity isoenzyme, the R-(-)-enantiomer was bound more strongly than the S-(+)-enantiomer.

Blood Proteins↗

PubMed1992

Serotyping and antigenic comparison of some animal rotaviruses isolated in China.

Eight strains of rotaviruses isolated from diarrheal animals (4 from calves and 4 from piglets) in China were compared by serotyping with reference animal rotavirus strains (bovine NCDV, porcine OSU and simian SA-11 and human rotavirus Wa strain). Two-way cross neutralization test showed no antigenic difference between all 4 local strains of bovine rotavirus (BRV007, BRV014, HN-7 and BRV6555) and reference NCDV, so they belonged to rotavirus serotype 6 (bovine rotavirus serotype 1 or NCDV-serotype). Meanwhile, the four strains of Chinese porcine rotavirus could be determined into 2 different serotypes. One (Li99) was neutralised to a high titer with the antiserum against reference OSU virus and probably related to OSU (serotype 5 or porcine serotype 1). The other three strains (Lin71, Nan86 and Jiang150) were antigenically obviously different from Li99 and did not react with the antiserum against OSU. They were tentatively considered as porcine rotavirus serotype 2. All the strains of bovine and porcine rotavirus did not cross-neutralise with simian SA-11 and human Wa strain. There was also no antigenic relationship between bovine rotaviruses and porcine rotaviruses.

Animals↗

PubMed1992

Oxidation of a specific methionine in thrombomodulin by activated neutrophil products blocks cofactor activity. A potential rapid mechanism for modulation of coagulation.

Endothelial thrombomodulin (TM) plays a critical role in hemostasis as a cofactor for thrombin-dependent formation of activated protein C, a potent anticoagulant. Chloramine T, H2O2, or hypochlorous acid generated from H2O2 by myeloperoxidase rapidly destroy 75-90% of TM cofactor activity. Activated PMN, the primary in vivo source of biological oxidants, also rapidly inactivate TM. Oxidation of TM by PMN is inhibited by diphenylene iodonium, an inhibitor of NADPH oxidase. Both Met291 and Met388 in the six epidermal growth factor-like repeat domain are oxidized; however, only substitutions of Met388 lead to TM analogues that resist oxidative inactivation. We suggest that in inflamed tissues activated PMN may inactivate TM and demonstrate further evidence of the interaction between the inflammatory process and induction of thrombotic potential.

Adult↗