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Biomedical subjects

J H Liu

Publications and source records attributed to J H Liu.

At least 19 recordsLinked to original sources
PubMed1992

Synthesis and antibacterial activity of 1-(substituted pyrrolyl)-7-(substituted amino)-6-fluoro-1,4-dihydro-4-oxo-3- quinolinecarboxylic acids.

Seventeen quinolone compounds characterized by having a fluorine atom at the 6-position, a substituted amino at the 7-position, and a substituted pyrrolyl at the 1-position were synthesized for the first time. The in vitro antibacterial activities of these compounds against Escherichia coli and Staphylococcus aureus were tested. Among these agents obtained, compound 24 showed significantly enhanced activity against S. aureus. The results indicate that there is much room for modifications at the N-1 position.

4-Quinolones↗
PubMed1992

Characterization of a gene family encoding abscisic acid- and environmental stress-inducible proteins of alfalfa.

The phytohormone abscisic acid (ABA) has been proposed as a common mediator controlling adaptive plant responses to a variety of environmental stresses, including water deficit, salinity, wounding, and low temperature. We have recently isolated three cDNAs, pUM90-1, pUM90-2, and pUM91-4, from a cDNA library of ABA-induced mRNAs of alfalfa. These cDNA clones exhibit a very high degree of sequence homology with one another and sequence similarities with certain regions of several stress- and ABA-inducible genes. The polypeptides encoded by these cDNAs are very rich in glycine (35-40%), histidine (7-15%), asparagine (8-14%), and tyrosine (5-10%) and have no tryptophan and proline. All of the encoded polypeptides contain characteristic tandem repeats comprising glycine residues intercepted with histidine and/or tyrosine. The RNAs corresponding to a representative cDNA, pUM90-1, were induced after treatment of seedlings with low temperature, drought, salt, and wounding stress, but not by heat; the induction was maximal under low temperature treatment. ABA and ABA analog rapidly induced the expression of these genes, whereas gibberellic acid treatment exhibited no induction whatsoever. These genes appear to be specifically induced in the shoot tissues. Analysis of ABA induction of genes corresponding to pUM90-1 in alfalfa seedlings of different age groups demonstrated that these genes were inducible in seedlings/plants of all age groups examined. Taken together these results suggest that these cDNA clones encode a group of proteins that are inducible by ABA and multiple environmental stresses and correspond to a new family of genes of plants, designated as ABA- and environmental stress-inducible genes.

Abscisic Acid↗
PubMed1992

Monosomy 21 in two patients with acute nonlymphocytic leukemia.

Among 50 cases of acute nonlymphocytic leukemia (ANLL) with available cytogenetic data seen in our section since May 1988, two were found to carry a monosomy 21 abnormality which has been rarely reported in hematologic malignancies. The first case is a 58-year-old male with a diagnosis of AML, FAB M2, who died of refractory leukemia 9 months later. The other case is a 59-year-old female with AML, FAB M2. Complete remission was achieved initially but she died of sepsis 3 months later with no evidence of leukemic relapse. Monosomy 21 is not yet recognized as a nonrandom cytogenetic abnormality in ANLL, whereas its unusual predilection in AML, especially the FAB M2 or M4 categories, as noted in our study and others' reports, have raised this possibility. Further studies and the accumulation of new cases are needed in the hope of defining it as a subtype of ANLL.

Chromosomes, Human, Pair 21↗
PubMed1992

V1-receptor mediated GSH efflux by vasopressin from rat hepatocytes.

Vasopression increases sinusoidal efflux of GSH in the perfused rat liver. The mechanism of this effect was studied in the perfused rat liver and in isolated rat hepatocytes. Vasopressin stimulated GSH efflux in both systems and a V1-receptor antagonist (OPC-21268) significantly inhibited the effect of vasopressin suggesting that vasopressin stimulates GSH efflux from rat hepatocytes via V1-receptor.

Angiotensin Receptor Antagonists↗
PubMed1992

Possible involvement of protein kinase C and calcium in GSH efflux from Hep G2 cells.

We investigated the effects of protein kinase C modulations and calcium mobilization on GSH efflux in Hep G2 cells. GSH efflux from Hep G2 cells was increased by a phorbol ester. Staurosporine, an inhibitor of protein kinase C, diminished phorbol ester-stimulated GSH efflux from the cells. GSH efflux was negatively correlated with extracellular calcium concentrations. Verapamil enhanced GSH efflux, whereas ATP decreased GSH efflux. The latter effect was diminished in the absence of extracellular calcium. Protein kinase C and calcium mobilization may be crucial factors in GSH efflux from human hepatocytes.

Adenosine Triphosphate↗
PubMed1992

Recombinant interleukin-8 induces changes in cytosolic Ca2+ in human neutrophils.

Activation of polymorphonuclear leukocytes (PMNL) by most soluble stimulants is associated with a marked increase in cytosolic free Ca2+ ([Ca2+]i). Interleukin-8 (IL-8), a monocyte-derived neutrophil chemotactic factor and potent neutrophil-activating cytokine, effectively enhanced the resting free [Ca2+]i within human PMNL in a dose-dependent manner (maximal effect with 100 ng/mL). The increase in [Ca2+]i was substantially (55%) inhibited in the absence of extracellular Ca2+. Thus, the increase was due to extra- and intracellular cooperative mobilization of Ca2+, as supported by the reduced effect of IL-8 on [Ca2+]i after quenching with Mn2+. Granulocyte-macrophage colony-stimulating factor and interferon-gamma failed to induce a change in [Ca2+]i, suggesting that they may operate through different signal pathways. Pretreatment with Bordetella pertussis toxin largely inhibited the IL-8-induced change in [Ca2+]i. Thus, IL-8-induced cooperative mobilization of intra- and extracellular Ca2+ leads to a net Ca2+ influx into the cytoplasm through a process mediated by a guanosine triphosphate-binding protein.

Calcium↗
PubMed1992

Bone marrow transplantation for severe aplastic anemia--a study of twenty-one Chinese patients in Taiwan.

A total of 21 multiply transfused patients with severe aplastic anemia (SAA) were treated with bone marrow transplantation between March 1985 and September 1990: 20 allogeneic and one syngeneic transplants. A positive response in mixed lymphocyte culture (MLC) was also noted in 7 allogeneic recipients. Pregraft conditioning included high-dose cyclophosphamide (CY) 200 mg/kg over 4 consecutive days, followed by 300 cGy total-body irradiation the day before BMT. Seventeen patients older than 14 years received additional donor buffy-coat cells infusion for 5 days posttransplant. A combination of methotrexate and cyclosporine was used for prophylaxis of graft-versus-host disease. Seventeen patients were alive with a functional graft, and Kaplan-Meier product limit estimates showed a 80.95% probability of survival at 67.7 months. There were 4 deaths: two died of primary graft failure, one from secondary rejection, and the other from chronic GVHD-related complications. Acute GVHD, grade I was noted in only one patient (5.6%). In contrast, chronic GVHD was observed in 10 out of 18 (55.6%) evaluable patients. Venoocclusive liver disease and interstitial pneumonitis were not diagnosed. Our findings indicate that the combination of CY/TBI/BC is well tolerated and results in a low incidence of graft failure/rejection in multiply transfused Chinese patients who received transplants for SAA. The MTX/CsA combination was confirmed as being remarkable in reducing the incidence and severity of acute GVHD. For patients with SAA under the age of 40, with an HLA-identical sibling, we highly recommend BMT as the treatment of choice.

Adolescent↗
PubMed1992

Evidence of a corticotropin-releasing hormone pulse generator in the macaque hypothalamus.

The secretion of hormones from the hypothalamic-pituitary axis is, in general, characterized by an episodic pattern of release. In the adrenal axis, ACTH and cortisol levels in peripheral blood display irregularly pulsatile ultradian patterns that are superimposed on the well characterized circadian rhythm. While it is generally accepted that CRH is released from the hypothalamus in a similar manner, very few studies have actually examined the temporal release of CRH. To examine the temporal release of CRH directly, we have established an in vitro perifusion system using the hemisectioned macaque hypothalamus. Perifusate samples were collected at 10-min intervals for 20 h and assayed for CRH by RIA. In control animals, a very regular, pulsatile pattern of hormone release was present, with a pulse interval of 90 +/- 11 min. Although this interval closely approximates the average pulse interval of ACTH and cortisol in the human, the regular pattern revealed in our study has not been demonstrated previously in the adrenal axis in vivo and suggests that factors outside the hypothalamus play a major role in controlling adrenal hormone levels. When hypothalami were perifused with dexamethasone added to the culture medium, no change in pulsatile activity was detected, indicating that a site outside of the hypothalamus may function as the primary center of feedback inhibition by adrenal glucocorticoids in the central nervous system. Because the very regular pulses of CRH that we observed bear striking similarity to the circhoral pulses of GnRH, we speculate that CRH may play a more subordinate role in regulating the adrenal axis and that other releasing factors and/or feedback effects at the pituitary level may be more important in the generation of the irregularly pulsatile, circadian patterns of ACTH and cortisol seen in peripheral blood.

Animals↗
PubMed1992

Transurethral resection in children with urethral stricture and occlusion.

Technical considerations of urethral surgery in children are critical because of the small size and delicacy of their urethra. From 1984 to 1989, 10 children with serious traumatic urethral stricture (5 cases) and occlusion (5) were treated satisfactorily by an improved transurethral resection (TUR). The age of the children ranged from 4 to 14 years. The TUR technique, curative effects and prevention of urethral stricture are discussed.

Adolescent↗
PubMed1992

Endoscopic management for traumatic occlusion of posterior urethra.

When traumatic posterior urethral transection occurs with serious pelvic fracture, the patient is usually under severe hemorrhagic shock and multiple injuries. It is of prime importance to treat shock and the associated injuries promptly. As for the urethral disruption a simple suprapubic cystostomy at the moment is preferred. Occlusion of the posterior urethra would eventually appear and can be managed endoscopically 3-6 months later. Fifteen such cases were thus managed from 1984 to 1990 with an improved endoscopic technique with a success rate of 93.3% (14/15). The advantages of this technique and the merits and demerits of various primary urethral reconstruction procedures are discussed.

Adolescent↗
PubMed1992

Aqueous humor messengers in the transient decrease of intraocular pressure after ganglionectomy.

Intraocular pressure (IOP) decreases in rabbits 1 day after superior cervical ganglionectomy. It was hypothesized that this IOP decrease was caused by an accumulation of norepinephrine (NE) released from the iris-ciliary body into the aqueous humor during nerve degeneration. Direct measurement of aqueous humor NE concentration, however, was not successful because of the technical difficulty. In the current study, aqueous humor NE after superior cervical ganglionectomy was extracted and quantified using high-performance liquid chromatography-electrochemical detection. Twelve New Zealand albino rabbits were maintained in a daily 12-hr light-12-hr dark environment. Unilateral ganglionectomy was done on these rabbits during the light phase under halothane anesthesia. Twenty-two hours after the procedure, a significant IOP decrease occurred. The IOP was 16.1 +/- 0.6 mmHg (mean +/- the standard error of the mean) in the operated eye and 20.9 +/- 0.6 mmHg in the contralateral eye (P < 0.01). Aqueous humor NE concentration in the operated eye (475 +/- 81 pg/ml) was not different from that in the contralateral eye (469 +/- 58 pg/ml). However, the concentration of aqueous humor cyclic adenosine monophosphate (cAMP) in the operated eye (29.8 +/- 6.8 pmol/ml) was significantly higher (P < 0.05) than that in the contralateral eye (11.7 +/- 0.8 pmol/ml). These data indicate that aqueous humor NE per se does not cause the transient IOP decrease after superior cervical ganglionectomy and cAMP-mediated ocular activities may be involved in this change in IOP.

Animals↗
PubMed1992

[Studies on the analytical method of a new anti-arrhythmic guan-fu base A in rabbit plasma].

Guan-fu base A, a new antiarrhythmic alkaloid with a structure of C20-diterpenoid, was first isolated from the tuber of Aconitum coreanum (Levl.) Raipaics in China in 1966. An analytical method of GC-ECD has been established in this paper for the determination of its concentration in rabbit plasma in order to study its pharmacokinetics in preclinical pharmacology. Guan-fu base A and the internal standard alprenolol (ALP) was found to react rapidly and quantitatively with trifluoroacetic anhydride (TFAA) to produce derivatives GFA-TFAA and ALP-TFAA which were identified by GC-MSD. An optimal GC-ECD system for the separation and determination of the derivatives following the sample preparation was established. There was a wide linear range of the method from 10-2 x 10(4) ng/ml (r = 0.9984). The average recovery of Guan-fu base A from the spiked plasma was 97.52%. The coefficient of variation of between-day and within-day were less than 9% and 7%, respectively. The method was used to determine Guan-fu base A in the plasma of 15 rabbits following intravenous administration of 3 dosages of 0.4, 2 and 10 mg per kg of body weight.

Alkaloids↗
PubMed1992

Functional compartments in the portal system. An experimental study.

The pressure of the portal trunk, the left gastric vein, the left and right gastroepiploic veins, the mesenteric vein and the abdominal aorta was measured experimentally at the same time in 10 normal dogs. The levels of the raised pressure in the different compartments with their outflow tracts obstructed respectively were observed and the potentials of the functional barriers between these compartments were quantitatively evaluated. The findings showed that the average power of the functional barriers was 45.1 +/- 5.7% between the different compartments in the gastrosplenic area and 74.3% in the mesenteric region. The weakness of the functional barriers' capacity limiting the collateral diversion between the lesser and greater splanchnic systems may be one of the causes making the distal splenorenal shunt lose its selectivity.

Animals↗
PubMed1992

Liver disease in patients with liver dysfunction prior to bone marrow transplantation.

Twenty-two patients with previous hepatic compromise who underwent allogeneic bone marrow transplant (BMT) for treatment of hematologic malignancy or other hematologic disease between 1984 and 1990 were chosen for the present study. After transplant, 19 (86.4%) of the patients developed hepatitis, including six cases (27.3%) of acute hepatitis, 12 (54.6%) of chronic hepatitis and one uncharacterized hepatitis. Nine chronic hepatitis patients were followed-up for 7-56.5 months (medium 35.5 months) with biochemistry studies and ultrasonography. Throughout the observation period, liver cirrhosis or hepatoma were not detected and no patients developed veno-occlusive disease. Furthermore patients who developed hepatitis after transplant had worse prognoses. Based on serial serological survey of the various hepatitis B virus (HBV) antigens and antibodies, we have found that most of the recurrent viral hepatitis in transplant patients could be attributed to the reactivation of the virus. In addition, the use of immunosuppressive drugs, persisting infection by HCV and the development of graft-versus-host disease may also play a role in modulating the course of viral hepatitis in BMT patients.

Adolescent↗
PubMed1992

Mitochondrial DNA mutation in Leber's hereditary optic neuropathy.

Leber's hereditary optic neuropathy (LHON) causes acute or subacute central visual loss in healthy young males. Recently, it has been thought to be caused by a single nucleotide change in the ND4 gene in the mitochondrial genome. Mitochondrial DNA (mtDNA) of leukocytes and hair follicle cells from five patients in four families with LHON and nine relatives were analyzed by Sfa NI and Mae III enzyme digestion and DNA sequencing. Loss of Sfa NI site was found in all patients and maternal lineages but not in nonmaternal lineages and normal controls. Mae III digested all the mtDNAs that lost the Sfa NI site. The restriction fragment pattern of polymerase chain reaction (PCR) products exhibited mtDNA heteroplasmy in the hair follicle cells but not in blood cells of the proband in one family. Direct sequencing of PCR-amplified mtDNA fragments encompassing the ND4 gene of the patients disclosed a transition from guanine to adenine at nucleotide position 11778. These results confirm previous reports that a G to A point mutation is associated with LHON and that tissue variability and heteroplasmy of mtDNA exist in some, but not all, LHON patients.

DNA↗
PubMed1991

Proton and carbon chemical-shift assignments for 6-kestose and neokestose from two-dimensional n.m.r. measurements.

The proton and carbon chemical shift assignments of the simplest levan, 6-kestose, [O-beta-D-fructofuranosyl-(2----6)-beta-D-fructofuranosyl-(2 in equilibrium with 1)-alpha-D-glucopyranoside], along with another trisaccharide, neokestose, [O-beta-D-fructofuranosyl-(2----6)-alpha-D-glucopyranosyl-(1 in equilibrium with 2)-beta-D-fructofuranoside], were determined using two-dimensional (2D) homonuclear and heteronuclear n.m.r. methods. The 1H peak of H-1 of the glucose residue was determined by its chemical shift. Using H-H coupling information to this proton, the chemical shifts of most of the proton signals of the glucose moiety were determined. Though the signals from the two fructose residues were very close, a NOESY experiment and long-range C-H correlation experiments allowed their complete carbon and proton assignment. This work completes and corrects literature assignments.

Carbohydrate Conformation↗
PubMed1991

Multiple therapies for vaginal bleeding secondary to large uterine myomas.

Acute vaginal bleeding secondary to uterine myomas can be a devastating event. We report the use of a combined therapeutic approach in a patient who presented with protracted bleeding of a myomatous uterus that was equivalent in size to a 38 week gestation. This patient's course was further complicated by her refusal of blood or blood products.

Acute Disease↗