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Biomedical subjects

Z H Zhang

Publications and source records attributed to Z H Zhang.

At least 19 recordsLinked to original sources
PubMed1995

Interaction of serotonin and norepinephrine in spinal antinociception.

The interactions between different doses of serotonin (5-HT) and norepinephrine (NE) in in vivo experiments on rat spinal cord dorsal horn cells was investigated using the integrated electromyography (EMG) measurement of the nociceptive hindlimb flexor reflex (FR). The results indicate that (1) intrathecal (IT) administration of low doses of 5-HT (60 nmol) or NE (1.5 nmol) suppresses the nociceptive FR by 40% for 20 min, respectively; (2) administration of higher doses of 5-HT (240 nmol, IT) multiplies the suppression of the nociceptive FR by 80% for 40 min, and NE (15 nmol, IT) produces similar suppression of the nociceptive FR for 80 min; (3) concomitant administration of low doses of 5-HT (60 nmol, IT) and NE (1.5 nmol, IT) produces a summation of the nociceptive FR suppression both in amplitude and duration; (4) concomitant administration of the higher doses of 5-HT (240 nmol IT) with NE (15 nmol, IT) produces similar effect obtained as 5-HT given separately, and no summation was obtained as observed following the lower dosages; (5) serotonin (240 nmol, IT) given 40 min before NE (15 nmol, IT) attenuates the duration of the suppression induced by NE; (6) pretreatment with a selective 5-HT2 receptor antagonist ketanserin (60 nmol, IT) failed to abolish the 5-HT effects; (7) pretreatment with ketanserin prior to concomitant administration of the higher doses of 5-HT and NE prolongs the time duration of the nociceptive FR suppression.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

LY 97241 accelerates the apparent rate of inactivation of transient outward K+ current: characterization of open channel block.

LY 97241 [(LY), p-nitro tertiary amine analog of clofilium] has been shown to prolong action potential duration in vitro but its effects on transient outward potassium current (Ito) are unknown. The authors investigated the effect of LY on Ito in rat ventricular myocytes using whole cell patch clamp techniques. LY resulted in a concentration-dependent inhibition of Ito amplitude (measured 30 msec after onset of depolarization) with an EC50 of 5.85 microM. The inhibitory effect of LY (10 microM) was seen at voltages from -30 to 70 mV (e.g., at 30 mV, LY reduced amplitude from a control of 7.29 +/- 0.30 to 3.05 +/- 0.22 pA/pF, P < .01, n = 10). The voltage-dependent block by LY was fitted by the Boltzmann equation, yielding a voltage for half-maximal block (V1/2) of -25.0 mV with a slope factor (k) of 13.8 mV. LY (10 microM) accelerated the rate of Ito inactivation from 41.9 +/- 3.5 to 16.0 +/- 1.6 msec without an effect on the peak of Ito (n = 10, P < .01). In contrast, 4-aminopyridine (4-AP, 1 mM) had no effect on the rate of inactivation but decreased the peak of Ito from 1.84 +/- 1.6 to 0.71 +/- 0.20 nA (n = 3). The time constant of onset of block (tau B) on Ito by 10 microM LY was fitted to a monoexponential function having a tau B of 14.5 +/- 1.5 msec. LY had no effect on the steady-state inactivation or recovery from inactivation of Ito.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1992

Effect of pCMBS on anion transport in human red cell membranes.

The kinetics of binding of the mercurial sulfhydryl reagent, pCMBS (p-chloromercuribenzene sulfonate), to the extracellular site(s) at which pCMBS inhibits water and urea transport across the human red cell membrane, have previously been characterized. To determine whether pCMBS binding alters Cl- transport, we measured Cl-/NO3- exchange by fluorescence enhancement, using the dye SPQ (6-methoxy-N-(3-sulfopropyl)quinolinium). An essentially instantaneous extracellular phase of pCMBS inhibition is followed by a much slower intracellular phase, correlated with pCMBS permeation. We attribute the instantaneous phase to competitive inhibition of Cl- binding to band 3 by the pCMBS anion. The ID50 of 2.0 +/- 0.1 mM agrees with other organic sulfonates, but is very much greater than that of pCMBS inhibition of urea and water transport, showing that pCMBS reaction with water and urea transport inhibition sites has no effect on anion exchange. The intracellular inhibition by 1 mM pCMBS (1 h) is apparently non-competitive with Ki = 5.5 +/- 6.3 mM, presumably an allosteric effect of pCMBS binding to an intracellular band 3-related sulfhydryl group. After N-ethylmaleimide (NEM) treatment to block these band 3 sulfhydryl groups, there is apparent non-competitive inhibition with Ki = 2.1 +/- 1.2 mM, which suggests that pCMBS reacts with one of the NEM-insensitive sulfhydryl groups on a protein that links band 3 to the cytoskeleton, perhaps ankyrin or bands 4.1 and 4.2.

4-Chloromercuribenzenesulfonate↗
PubMed1992

15NH4+ excretion test: a new method for detection of Helicobacter pylori infection.

A noninvasive test for the detection of Helicobacter pylori infection that uses [15N]urea as a tracer has been established. The principle the test is based on is the strong urease activity of H. pylori. After oral ingestion, [15N]urea is broken down into ammonia and carbon dioxide by H. pylori urease in the stomach. The ammonia is absorbed into the blood and excreted in the urine. The amount of [15N]urea, reflecting the magnitude of H. pylori infection, is evaluated by measuring the abundance and excretion rate of 15N in ammonia in the urine. Thirty-six patients were examined in our study. The 15N excretion rates in urine ammonia of patients who were H. pylori positive were significantly higher than those of H. pylori-negative patients (P less than 0.05). Twenty-three patients were H. pylori positive by Gram stain and culture. The sensitivity of the 15NH4 excretion test compared with these techniques was 96%, and no false positives were obtained. The 15NH4+ excretion rates of 13 H. pylori-negative subjects were all in the normal range (less than 0.3%). This method is a simple, precise, highly sensitive, noninvasive, nonradioactive test. It could be used for diagnosis as well as for the followup of patients receiving H. pylori eradication therapy, especially children and pregnant women. It could also be used in epidemiological investigation of H. pylori infection in a general population.

Adult↗
PubMed1992

[Solid-phase extraction and RP-HPLC screening procedure for diuretics, probenecid, caffeine and pemoline in urine].

A solid-phase extraction and reversed phase high performance liquid chromatographic method (RP-HPLC) was developed for the rapid determination of 13 diuretics (belonging to five different pharmacological groups), probenecid, caffeine and pemoline in urine. Two ml urine sample was first adsorbed on a XAD-2 column, then eluted with ether-ethyl acetate (1:1). The eluate was evaporated to dryness and reconstituted in methanol. The methanolic solution was injected into a HP LiChrosorb RP-18 column, using phosphate buffer (pH 3) and acetonitrile as the mobile phase and monitored at 216 nm, 230 nm, and 275 nm on a diode array ultraviolet detector. The extraction recoveries of 16 drugs were above 75%. The limits of detection ranged from 0.3-3.0 micrograms/ml of urine. All drugs were separately administered to healthy volunteers, positive urine samples were collected, and urinary excretion-time curves of some drugs were reported.

Adult↗
PubMed1992

[Comparison of mosquito larvicidal efficacy between microbial encapsulated BTI (EBTI) and standard BTI (SBTI)].

A comparative study was conducted on the efficacy of mosquito larvicides EBTI and SBTI. The results showed that: 1. The residual efficacy of EBTI was remarkably higher than that of SBTI at 0.007-0.002ppm BTI concentration (P < 0.01), the mosquito larvae mortality of EBTI remained 100% until the 4th week; in contrast, the mosquito larva mortality of SBTI gradually and obviously declined from the 2nd to 4th week after treatment (x2 = 8.17-24.08), and reached 0 at the 4th week. 2. The lowest BTI concentration of EBTI at which a high efficacy persisted for 4 weeks was 0.007ppm BTI, the mosquito larva mortality remaining 100%.

Animals↗
PubMed1992

[Carcinoid of the digestive tract. An analysis of 36 cases].

36 cases of carcinoid of the digestive tract were presented. The malignancy of the carcinoid was established solely by the presence of local infiltration and remote metastasis irrespective of the size of the original tumor three of 10 cases of the tumor less than 2 cm in diameter had metastasis although smaller tumors were usually benign. Immuno-histochemistry study in 15 cases showed 1-4 kinds of different polypeptides in each case. Three of 8 cases of malignant carcinoid syndrome had normal blood level of 5-HT and 5-HIAA, suggesting other polypeptides as the cause of the syndrome. The absence of hepatic metastasis in 4 of the 8 cases favors the hypothesis that polypeptides may get access to the general circulation by such as retroperitoneal pathways.

Adolescent↗
PubMed1992

Effect of ambasilide, a new class III agent, on plateau currents in isolated guinea pig ventricular myocytes: block of delayed outward potassium current.

The actions of ambasilide (LU-47110) on the action potential and membrane currents of isolated guinea pig ventricular myocytes were studied using voltage clamp techniques. Ambasilide (1 microM) prolonged the action potential (APD) at 20, 50 and 90% repolarization by 11.2 +/- 4.3, 13.8 +/- 3.9 and 13.6 +/- 3.7%, respectively, compared to control (n = 10). APD prolongation was attributed to the block of delayed rectifier outward current (Ik) in a concentration-dependent fashion (0.01-10 microM). The effects on the APD and Ik were both partially reversed after perfusion with drug-free Tyrode's solution. The block of Ik by ambasilide was compared to that by E-4031 (5 microM), a putative selective blocker of that fast, inwardly rectifying component of Ik identified in guinea pig ventricle. E-4031 produced about 65% block of Ik for pulse durations between 80 and 420 msec, but the block decreased as the pulse duration increased further, the block accounting for 34 +/- 5% of Ik at 6.3 sec. In contrast, the percentage of reduction of Ik by 10 microM ambasilide did not produce a consistent magnitude of block over a similar range of short depolarizations, but rather progressively decreased Ik as the pusle duration lengthened. Block at the end of a 2-sec pulse was about 48 +/- 8%, more block than could be attributed to an E-4031-sensitive current block alone. Whereas E-4031 (5 microM) shifted the activation curve of Ik 10 mV toward positive potentials and decreased the slope factor, k, by about 4 mV, ambasilide (5 microM) had no effect on these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1991

The gene for the alpha 4 subunit of the VLA-4 integrin maps to chromosome 2Q31-32.

The VLA-4 integrin (CD49d/CD29), initially discovered on lymphoid cells, is actually known to be highly expressed on T cells, B cells, monocytes, and derived cell lines. Unlike other VLA integrins, mainly involved in cell-matrix adhesive interactions, VLA-4 has also been implicated in several cellular interactions. Based on the published alpha 4 cDNA sequence, a 1,142-bp alpha 4 cDNA fragment was amplified using the polymerase chain reaction. This fragment was used to isolate three overlapping genomic clones from a phage library. By Southern analysis with the cDNA probe, and using the polymerase chain reaction on DNA isolated from a panel of human/mouse somatic cell hybrids, the alpha 4 gene was mapped to chromosome 2. Fluorescence in situ hybridization confirmed this assignment and allowed a more precise mapping to chromosome 2q31-32.

Animals↗
PubMed1991

Effects of stimulation of superior colliculus on nociceptive unit discharges in parafascicular neurons and nocifensive reflex of hind limb in rat.

Effects of stimulation of the superior colliculus (SC) on the spontaneous and nociceptive discharges of parafascicular (PF) neurons were investigated in 43 urethane-anesthetized rats. Two groups of PF cells were sampled according to their responses to noxious stimuli: 59 of them were 'nociceptive-on' and 12 'nociceptive-off'. Following stimulation of the intermediate and deep layers of SC, the firing rate of nociceptive discharge of 'nociceptive-on' cells was inhibited significantly (-76 +/- 5%, P less than 0.01) in 75% cases tested, while the nociceptive response of 'nociceptive-off' cells was disinhibited markedly (79 +/- 9%, P less than 0.01) in 67% cases by the same stimulation. In 30 animals of this series the latency of hind limb withdrawal reflex elicited by noxious skin heating was compared before and after SC stimulation. In 24 cases in which the stimulating electrodes were positioned exactly in intermediate-deep layers of SC, SC stimulation lengthened the latency by 62 +/- 8% (P less than 0.01), while in 6 cases in which the electrodes drifted from these areas, the latency was not changed following the same stimulation.

Animals↗
PubMed1991

Characterization of stage-specific antigens of Paragonimus westermani.

In order to develop a serodiagnostic assay to detect antigens of Paragonimus westermani in biological specimens, we generated monoclonal antibodies to antigens of metacercariae and adult worms, and partially characterized the epitopes recognized by representative Mabs. Metacercarial stage-specific determinants were periodate-sensitive and protease-resistant, indicating that they are carbohydrate epitopes. In contrast, adult worm-specific determinants resisted periodate treatment but were sensitive to proteases, indicating that they are polypeptides. The majority of cross-reactive Mabs studied were directed against phosphorylcholine determinants. When used in a dot-ELISA, Paragonimus-specific Mabs could detect 0.3-7 ng/ml parasite antigen in human sera.

Animals↗
PubMed1991

Enzyme-linked immunosorbent assay for detection of immunoglobulin G antibody against Helicobacter pylori.

Eight strains of sonicated Helicobacter pylori (H. pylori) were pooled as group antigen to detect the serum IgG antibody to H. pylori in patients with various gastroduodenal diseases and subjects at health check-up. The enzyme-linked immunosorbent assay method used had a sensitivity of 94%, a specificity of 87%, and a positive predictive value of 96%. The prevalence of serum IgG antibody to H. pylori was 19.0% in patients with Type A gastritis, 76.0% in patients with Type B gastritis, 91.5% in duodenal ulcer, and 92.9% in gastric ulcer. Moreover, the prevalence of serum IgG antibody to H. Pylori in newborns was 53% (probably acquired from mother), in children below 10 years old was 25%. The detection rate gradually rose to 70% with the increase of age, but decreased to 40% in those over 70 years of age.

Adolescent↗
PubMed1990

Study of the effects and mechanisms of berberine on slow-response action potentials.

The effects of berberine on slow-response action potentials (SAP) of guinea pig papillary muscles were studied. SAP was elicited by histamine in a high concentration of potassium solution (27 mmol). The results showed that berberine (24.5 mumol) was able to increase action potential amplitude, maximum rate of depolarization, action potential duration 50, action potential duration 100 (n = 16, p less than 0.01) and effective refractory period (n = 10, p less than 0.01) of SAP by 6.2%, 21.1%, 50.1%, 47.2% and 92.2%, respectively, but did not affect the resting membrane potential (RMP). To the above parameters, except APD 100, berberine was no longer to induce any significant change by pretreating with propranolol. The results suggested that the effects of berberine on slow-response action potentials were mainly related to the facilitating of slow calcium inward current, which might result from stimulating the beta-adrenoceptor.

Action Potentials↗
PubMed1990

[Chemical studies on polysaccharide of Achyeanthes bidentata].

A peptide-polysaccharide, ABAB showing immunological activity was isolated from Achyeanthes bidentata Bl. It was shown to be homogeneous by HPLC and optical rotation analysis. Its molecular weight was estimated to be 2.3 x 10(4). It composed of D-glucuronic acid, D-galactose, D-galacturonic acid, L-arabinose and L-rhamnose in molar ratio of 12:2:3:1:1. Reduction of carboxyl groups, methylation analysis, periodate oxidation, Smith degradation and IR analysis showed that ABAB possesses a main chain composed of (1----4)-D-glucuronic acid and (1----4)-D-galacturonic acid residues. The non-reducing terminal residues in the side chains were L-arabinose and L-rhamnose. ABAB contained 24.1% of peptides composed of glycine, glutamic acid, aspartic acid and serine.

Drugs, Chinese Herbal↗
PubMed1990

The efficacy of furazolidone and metronidazole in the treatment of chronic gastritis associated with Helicobacter (Campylobacter) pylori--a randomized double-blind placebo-controlled clinical trial.

Seventy-two patients with Helicobacter pylori-associated chronic gastritis were randomized to a 3-week oral treatment with furazolidone 0.1g t.i.d. or metronidazole 0.2g t.i.d. or placebo. Endoscopy was performed before and after treatment, and biopsy specimens were taken from the antrum of the stomach for histological examination and culture of Helicobacter pylori. Disappearance rates of Helicobacter pylori in furazolidone, metronidazole and the control groups were 74% (20/27) if considering completion of therapy, the 20/25 or 80%, 33.3% (8/24) and 14.3% (3/21) respectively. There was a significant difference in the disappearance rate of Helicobacter pylori between furazolidone and metronidazole, and between furazolidone and the placebo group (p less than 0.01), but there was no such difference between metronidazole and the placebo group (p greater than 0.05). In the patients receiving furazolidone, the eradication of Helicobacter pylori was accompanied by marked improvement in both inflammatory infiltration in the gastric mucosa and symptoms. These results reasonably suggest that Helicobacter pylori may play an etiological role in the pathogenesis of chronic gastritis, and that furazolidone is effective in the treatment of Helicobacter pylori-associated chronic gastritis.

Adolescent↗
PubMed1989

Normal and leukemic lymphocyte membrane fluidity and response to stimulation with ConA and PHA.

In our experiment, lymphocyte membrane was labeled by DPH fluorescence probe. The rate of rotation of the probe can be measured from the value of fluorescence polarization (PDPH). With this method useful information could be provided about membrane fluidity of lymphocytes. It was found that the F value (unit of lipid fluidity of membrane) of leukemic lymphocytes was obviously higher than that of normal ones. Furthermore, the F value of cultured leukemic Ts lymphocytes was the highest. In contrast with normal spleen T-lymphocytes or mixed lymphocytes, the response of malignant lymphocytes to the stimulation with ConA or PHA was reflected in the decrease of PDPH value or the increase of F value. Unexpectedly, the F value of T-lymphocytes from "615" mouse not injected with tumour cells was also higher than that of the mixed. The possibility of using the membrane fluidity as a diagnostic criterion was also discussed.

Animals↗