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Biomedical subjects

H L Wang

Publications and source records attributed to H L Wang.

At least 19 recordsLinked to original sources
PubMed1995

Neurotensin increases the cationic conductance of rat substantia nigra dopaminergic neurons through the inositol 1,4,5-trisphosphate-calcium pathway.

Whole-cell patch-clamp recordings were used to investigate electrophysiological effects of neurotensin on acutely isolated dopaminergic (DA) neurons of the rat substantia nigra pars compacta (SNC). During current-clamp recordings, neurotensin depolarized DA neurons and triggered action potentials. Under voltage-clamp recordings, neurotensin evoked an inward current at a holding potential of -50 mV. Neurotensin-induced inward currents reversed the direction at -5 mV and became smaller as the membrane potential was hyperpolarized from -75 mV. With potassium-free recording solutions, neurotensin evoked voltage-insensitive cationic currents. With sodium-free external solution, neurotensin also caused inward currents by reducing the inwardly rectifying potassium conductance. Neurotensin-induced inward currents mainly resulted from an increase in a non-selective cationic conductance. Neurotensin-evoked cationic currents were inhibited by the intracellular perfusion of 1 mM guanosine-5'-O-(2-thiodiphosphate). In DA neurons internally perfused with 0.5 mM guanosine-5'-O-(3-thiotriphosphate), the cationic current produced by neurotensin became irreversible. Pretreating DA neurons with 500 ng/ml pertussis toxin (PTX) did not significantly affect the ability of neurotensin to evoke cationic currents. Internal perfusion of heparin (2 mg/ml), an inositol 1,4,5-trisphosphate (IP3) receptor antagonist, and buffering intracellular calcium with the Ca(2+)-chelator BAPTA (10 mM) suppressed neurotensin-induced cationic currents. Dialyzing DA neurons with protein kinase C (PKC) inhibitors, staurosporine and PKC(19-31), failed to prevent neurotensin from evoking cationic currents. It is concluded that PTX-insensitive G-proteins mediate neurotensin-induced enhancement of the cationic conductance of SNC DA neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Protein kinase C mediates neurotensin inhibition of inwardly rectifying potassium currents in rat substantia nigra dopaminergic neurons.

Whole-cell voltage-clamp recordings were used to investigate the molecular transduction mechanism by which neurotensin decreases the inwardly rectifying potassium conductance of dopaminergic (DA) neurons acutely isolated from the rat substantia nigra (SN). With sodium-free external solution, neurotensin evoked inward currents by reducing the inwardly rectifying K+ conductance. Neurotensin inhibition of the K+ current was blocked by the internal perfusion of 1 mM GDP-beta-S. When DA neurons were internally perfused with 0.5 mM GTP-gamma-S, the reduction of K+ conductance produced by neurotensin became irreversible. Neurotensin still inhibited K+ currents in DA neurons pretreated with 500 ng/ml pertussis toxin (PTX). Dialyzing DA neurons with protein kinase C (PKC) inhibitors, staurosporine and PKC(19-31), prevented neurotensin from decreasing the potassium conductance. Our results propose that neurotensin activates PKC of SN DA neurons via PTX-insensitive G-proteins and that PKC mediates the neurotensin inhibition of inwardly rectifying potassium currents.

Animals↗
PubMed1995

Evaluation of a collagen membrane with and without bone grafts in treating periodontal intrabony defects.

The aim of this study was to compare the clinical regenerative capacity of collagen membrane with and without demineralized freeze-dried bone allografts (DFDBA) in treating periodontal intrabony defects. Ten systemically healthy patients with similar bilateral periodontal defects were scheduled for surgery. Each patient had at least > or = 6 mm clinical probing depth and loss of attachment at selected sites. Baseline measurements included gingival index (GI), plaque index (PI), gingival recession (GR), clinical attachment level (CAL), probing depth (PD), and mobility. At the time of surgery, the defects were randomly assigned to either test (collagen membrane plus DFDBA) or control group (collagen membrane only). Stent to base of the defects, stent to crest bone, crest of bone to base of the defect, and width of the defects were recorded at the time of surgery and reentry. Eight patients returned after 6 months for reentry surgery. Statistical analysis with a paired t test was used to evaluate the treatment effect and comparison between test and control groups. In addition, a McNemar test was used to analyze the significance of GI, PI, and mobility at different times. The result of this study indicated that both the collagen plus DFDBA and the collagen alone treatment groups had a significant decrease of PD (3.4 +/- 0.4 and 3.2 +/- 0.4 mm), gain of CAL (2.3 +/- 0.5 and 2.0 +/- 0.4 mm), and defect fill (1.7 +/- 0.3 and 1.9 +/- 0.9 mm) (P < 0.05) when compared to the presurgery status. However, there was no significant difference in PD, AL, GR, defect fill, crestal bone resorption, GI, PI, or mobility between the test group and control group. No adverse tissue reaction, infection, or delayed wound healing was noted throughout the treatment in either group. This study suggests that the collagen membrane is well tolerated by the human tissues. Both treatments, either collagen membrane plus DFDBA or collagen membrane alone, promoted significant resolution of periodontal intrabony defects. The addition of a bone graft (DFDBA) with a collagen membrane appears to add no extra benefit to the collagen membrane treatment.

Adult↗
PubMed1995

A molecular study of ocular herpes simplex infection in Kaohsiung, Taiwan. Part I: Cleavage pattern analysis.

In order to investigate the relationship between genotypes of herpes simplex virus (HSV) and its clinical pictures in herpes simplex virus keratoconjunctivitis (HSK), fifty nine strains of HSV isolates, collected in the Kaohsiung Medical College Hospital during January 1981 to July 1991, and F strain (ATCC VR-73), a standard HSV-1, were studied. The viruses were isolated from HSK patients. All 59 strains were identified as HSV-1 using immunofluorescence monoclonal antibody method. The HSV DNAs were extracted and digested by restriction enzymes, BamH I, Kpn I and Sal I, followed by electrophoresis, and photographing. Six kinds of DNA cleavage patterns were found in Taiwan. The majority were E subtype (56.4%) then A subtype (27.3%), D subtype (7.3%), F subtype (5.4%), G subtype (1.8%) and H subtype (1.8%). Subtypes B and C were not found in this study. The cleavage patterns of two recurrent cases belonged to E and A subtypes. The identical cleavage patterns of two bilateral infections all belonged to the E subtype.

Animals↗
PubMed1995

[Novel GABAc receptors].

Considerable evidence has shown that there is a kind of special pharmacological GABA receptors in central nervous system, especially prominent along visual pathways. These receptors are neither antagonized by bicuculline nor activated by baclofen, but are activated selectively by the GABA analogue cis-4-aminocrotonic acid (CACA), its response did not show desensitization. These receptors have been termed GABAc receptors. It may play an important role in the visual information transmission and modulation of retinal rod pathway.

Animals↗
PubMed1994

CCK-8-evoked cationic currents in substantia nigra dopaminergic neurons are mediated by InsP3-induced Ca2+ release.

Our recent study demonstrated that by activating CCK-A receptors, CCK-8 excites substantia nigra (SN) dopaminergic (DA) neurons via increasing a non-selective cationic conductance. In the present study, we further studied the molecular mechanism by which CCK-8 induces cationic currents in SN DA neurons. CCK-8-evoked inward currents were inhibited by the intracellular perfusion of GDP-beta-S (1 mM). In DA neurons internally perfused with GTP-gamma-S (0.5 mM), the inward currents produced by CCK-8 became irreversible. Pretreating DA neurons with 500 ng/ml pertussis toxin (PTX) did not significantly affect the ability of CCK-8 to induce cationic currents. Intracellular application of heparin (2 mg/ml), an inositol 1,4,5-trisphosphate (InsP3) receptor antagonist, and buffering intracellular calcium with the Ca(2+)-chelator BAPTA (10 mM) suppressed CCK-8-evoked cationic currents. Dialyzing DA neurons with protein kinase C (PKC) inhibitors, staurosporine and PKC(19-31), failed to prevent CCK-8 from generating cationic currents. It is concluded that PTX-insensitive G-proteins mediate CCK-8-induced enhancement of cationic conductance of SN DA neurons. The coupling mechanism via G-proteins is likely to involve the generation of InsP3, and subsequent InsP3-evoked Ca2+ release from the intracellular store results in activating the non-selective cationic conductance.

Alkaloids↗
PubMed1994

CCK-8 excites substantia nigra dopaminergic neurons by increasing a cationic conductance.

Using the whole-cell patch-clamp technique, we investigated electrophysiological effects of cholecystokinin on acutely isolated dopaminergic (DA) neurons of rat substantia nigra (SN). During voltage-clamp recordings, sulfated cholecystokinin octapeptide (CCK-8) dose-dependently induced an inward current at the holding potential of -7O mV. Under current-clamp recordings, CCK-8 depolarized DA neurons and triggered action potentials. CCK-8-evoked inward current reversed its direction at 1.0 +/- 1.9 mV (n = 9), and the amplitude of inward current induced by CCK-8 was reduced in an external solution with low sodium concentration. Cholecystokinin tetrapeptide (CCK-4), a selective CCK-B receptor agonist, failed to induce an inward current. CCK-8-evoked cationic current was antagonized by lorglumide, a selective CCK-A receptor antagonist. PD135, 158, a highly selective and potent CCK-B receptor antagonist, failed to attenuate CCK-8-induced cationic currents. These results suggest that by activating CCK-A receptors, CCK-8 excites SN DA neurons via increasing a non-selective cationic conductance.

Animals↗
PubMed1994

The influence of molar furcation involvement and mobility on future clinical periodontal attachment loss.

The purpose of this study was to determine the influence of furcation involvement (FI) and mobility (MO) on change in probing periodontal attachment level (AL) on molar teeth. Twenty-four patients were selected from The University of Michigan longitudinal periodontal clinical trial. The patients who met the entry criteria received a baseline examination and were treated by periodontal scaling and root planing followed by different periodontal surgical approaches in a split-mouth design. Patients were placed on a 3-month interval for maintenance prophylaxis and had yearly periodontal scorings for a period of 8 years. The scorings included determination of AL, FI, MO, and tooth loss (TL). Data for molar teeth from three different time periods (at entry (A) and at 1 (B) and 8 (C) years) were analyzed. The results demonstrated that teeth with FI were 2.54 times more likely to be lost when compared to teeth without FI during the maintenance period. By using paired t test approach to the probing attachment level data, molars with FI had significantly more loss between times B and C but not between A and B or A and C. Teeth with increased MO demonstrated significantly more AL between times A and C and B and C. When the interaction between MO and FI was analyzed, teeth with both FI and MO had significantly more attachment loss during the maintenance period (B to C). No statistically significant difference was found among the three different therapeutic approaches (pocket elimination, curettage, and modified Widman flap) during any of the time periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Evaluation of an absorbable collagen membrane in treating Class II furcation defects.

Recent research has focused upon the utilization of an absorbable collagen membrane in guided tissue regeneration (GTR). Concern exists as to whether this type of membrane is beneficial in the treatment of periodontal defects. The purpose of this study was to evaluate the effect of a type I bovine collagen membrane on treatment of Class II furcation defects. Twelve systemically healthy patients (six male and six female, ages 32 to 68) were treated. Each had bilateral mandibular furcation defects with attachment loss > or = 6 mm. Prior to surgery all patients completed initial therapy including scaling and root planing. At the time of the surgery, teeth were randomly assigned to either a control (flap debridement alone) or test (flap debridement plus collagen membrane) group. Data were collected on the day of surgery, and 2, 4, and 6 months post-surgery and at the 12 month re-entry surgery. Clinical measurements included probing depth (PD), clinical attachment level (CAL), gingival recession (GR), stent to base of defect (SB), crestal bone to base of defect (CB), width of defect, and mobility. Statistical analysis was performed utilizing the paired t test. Both control and test groups demonstrated significant (P < 0.05) improvement at 12 months re-entry in PD, CAL, SB, and CB when compared to the presurgery status. While there is no significant difference in PD, CAL, GR, width of defect, and mobility between control and test groups, sites treated with the collagen membrane had significantly higher bone fill (SB and CB) at re-entry.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Adherence of oral microorganisms to guided tissue membranes: an in vitro study.

Microorganisms can adhere and colonize on an exposed guided tissue regeneration (GTR) membrane thus developing a nidus of infection. The purpose of this study was to compare early bacterial adhesion to three different GTR membranes. Expanded polytetrafluoroethylene, polyglactin 910, and collagen were used as the test membranes. In part I of this study 15 different oral microbes were used to compare their relative ability to adhere to the membranes. Six of the most strongly adherent bacteria (Actinomyces viscosus, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Streptococcus mutans, Fusobacterium nucleatum, and Selenomonas sputigena) were selected for part II of this study. The membranes were placed in tubes containing broth cultures containing identical concentrations (1 x 10(8) cells/ml) of these bacteria at 37 degrees C. Membranes were placed in tubes of media without bacteria as controls. At 4, 6, 12, and 24 hours, the bacterial cultures were decanted and the membranes in the tubes were agitated gently in reduced transfer fluid (RTF) 4 times to remove non-adherent bacteria. Each tube was then sonicated for 30 seconds in 10 ml RTF to detach adherent bacteria. The detached adherent bacteria were counted using a Petroff-Hausser chamber. Data were analyzed by using the SAS program. Analysis of variance was used to test for differences between multiple means. Results showed S. mutans had the strongest attachment to the collagen membrane at 4 and 6 hours. Selenomonas sputigena had the lowest adherence capability to all test membranes. Polyglactin 910 had significantly (P < 0.05) lower S. mutants adherence than either the ePTFE or the collagen membrane at 4 and 6 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces viscosus↗
PubMed1994

The effect of platelet-derived growth factor on the cellular response of the periodontium: an autoradiographic study on dogs.

Platelet-derived growth factor (PDGF) is a polypeptide growth factor considered to have a role in the proliferation and migration of fibroblasts at a wound healing site. The aim of this investigation was to determine if PDGF, when applied to root surfaces, would stimulate the proliferation of fibroblasts and further enhance regeneration. Six mongrel dogs with healthy periodontia were selected for this study. Using a closed wound surgical model, standardized 4 x 4 mm fenestration defects were created into dentin on the mid-facial of the mesial and distal roots of 4 mandibular posterior teeth in each quadrant. Each defect received either: 1) saline solution (C); 2) expanded polytetrafluoroethylene (ePTFE) membrane; 3) PDGF; or 4) ePTFE + PDGF. 3H-thymidine was administered 1 hour prior to animal sacrifice at 1, 3, and 7 days postsurgery. Each time period included 2 dogs with each dog undergoing the four different treatments. Slides were prepared for autoradiography. 3H-thymidine-labeled cells were counted and results were statistically analyzed using the Bonferroni (Dunn) t test on the SAS program. Results indicated PDGF enhanced fibroblast proliferation when compared to the groups without PDGF. Significant differences (P < 0.05) were noted at day 1 and 7 when PDGF and PDGF + GT were compared to C and GT groups. No significant differences were observed in labeled fibroblasts between the C and GT groups at any time period. These findings suggest that PDGF enhances fibroblast proliferation in early periodontal wound healing, whether used alone or in combination with the ePTFE membrane.

Analysis of Variance↗
PubMed1994

Electrochemical therapy of 74 cases of liver cancer.

Ninety-four patients with primary liver cancer have been treated with electrochemical therapy (ECT) in our hospital. Seventy-four cases were followed up for more than one year, 12 cases for less than one year, and 8 cases were lost. Seventy-four cases of stage II and III liver cancer were divided into three groups. Group A received ECT only, group B received ECT plus transcatheter hepatic artery infusion chemotherapy (TAI) and embolisation (IAE) treatment. Group C received ECT plus systemic chemotherapy. The survival rate at 12 months was 58% for group B patients, which was significantly higher than for group A or C patients. We found ECT to be relatively simple and safe. The main side effect is short-time fever after treatment.

Adult↗
PubMed1994

[Drug resistance and plasmid analysis in Pseudomonas aeruginosa].

One hundred and ninety seven strains of Pseudomonas aeruginosa were isolated from urine (59 strains), wound pus (60 strains), sputum (30 strains), stool (30 strains) and eye discharge (18 strains) at Kaohsiung medical College Hospital. These strains were serotyped with antisera against O antigens and tested with twelve different antimicrobial agents. The results showed that the most frequently isolated strains were serotype E (41.1%), followed by serotype B (20.3%), serotype F (10.7%) and serotype L (9.1%). In in vitro susceptibility testing, all isolated strains were resistant to chloramphenicol and tetracycline. Otherwise, these isolates were highly susceptible to ceftazidime (95.4%), enoxacin (89.3%) and piperacillin (87.8%). The isolates from urine exhibited more multiple drug resistance patterns than those of other specimens. When plasmid content was analysed from pseudomonas aeruginosa, only 15.2% (30/197) of isolates carried plasmids. By conjugation, transformation and mobilization experiments, it was shown that 13.3% (4/30) of plasmid carrying strains contained R plasmids.

Chloramphenicol↗
PubMed1994

Effect of root conditioning on periodontal wound healing with and without guided tissue regeneration: a pilot study. II. Autoradiographic evaluation.

This investigation deals with the proliferation and migration of the progenitor cells during the healing of closed periodontal wounds. Periodontal surgical defects affecting the bone and dentin were created in four mongrel dogs. The defects were treated with topical applications of citric acid, tetracycline, or sterile water with and without the placement of nonresorbable membranes. The dogs were killed at 1, 3, 7, and 21 days after surgery. One hour before they were killed, they were intravenously injected with tritiated thymidine. Tissues were processed and routinely prepared for autoradiographic studies. Labeled cells were counted at the apical, coronal, and central areas of the defects. Results suggested that the citric acid and tetracycline treatments inhibited cellular proliferation at the initial time periods of 1 and 3 days. At 7 and 21 days, differences between citric acid and tetracycline treatments were minimal, and neither showed any advantage over the application of sterile water. The placement of the nonresorbable membrane demonstrated a trend of increased labeling at 21 days for all three treatments.

Acid Etching, Dental↗
PubMed1994

Cells and materials involved in guided tissue regeneration.

Just over 10 years ago a group of imaginative periodontal researchers reported that tissues lost to the destructive mechanisms of inflammatory periodontal disease could be regenerated either in part or whole by the use of a surgical technique that would become universally known as guided tissue regeneration. Since then, tremendous progress has been made in adapting these early research principles into a clinical treatment modality that is now recognized as a viable component of contemporary periodontal therapy. However, many questions remain as to the mechanisms involved in regenerative tissue formation and how to design surgical procedures and materials to best harness the regenerative capacities of the periodontium. This article reviews current concepts and controversies regarding the biologic basis of periodontal regeneration and biomaterials used in guided tissue regeneration therapy. Pros and cons related to regenerative techniques currently in use are discussed along with future directions in the field of periodontal regeneration.

Extracellular Matrix Proteins↗
PubMed1994

Study on some biological and antigenic characteristics of CA24v isolates in Taiwan in 1985-1989.

In order to understand the relationship between the CA24v isolates which caused two epidemics of acute hemorrhagic conjunctivitis (AHC) in 1985-1986 and 1988-1989 in Taiwan, biological and antigenic characteristics were studied with four CA24v strains, L077/85, V116/86, 590/88 and 722/89, which were isolated during the epidemics. The prototype strain, EH24/70, was used for comparison. In terms of cross neutralization, kinetic neutralization, plaque assay and protein electrophoresis, no obvious differences were found between the isolates from the two epidemics though differences were found between these isolates and the prototype.

Conjunctivitis, Acute Hemorrhagic↗
PubMed1994

[Clinicopathologic changes in leukemic lung lesions].

Leukemic lung lesions are complex and various. The authors studied the clinicopathologic changes in 104 autopsied leukemic cases collected from 1953 to 1990. 22.1% of the cases had the symptoms of respiratory tract admission and 40.4% developed the symptoms before death. 12.8% of the patients were diagnosed with X-ray to have tuberculosis and infections on admission and 42% cases have these changes in the terminal phase. The main pathological changes are pleural effusion, pleural adhesion, intrapulmonary infections, hemorrhage and Myleran lung. The rate of leukemic cell infiltration in lungs was 96.2% and the infiltration was mainly interstitial. Intravascular leukemic cell stasis was found in 91.3% of the cases. The pathological changes in each case were usually multiple and 84.6% of the cases had more than two kinds of changes. We compared the X-ray diagnoses with pathological ones and it was shown that complete coincidence was present only in 2.9%, partial coincidence in 58.8% and no coincidence in 38.3% of the cases.

Adolescent↗