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Biomedical subjects

B C Sun

Publications and source records attributed to B C Sun.

At least 19 recordsLinked to original sources
PubMed2005

The SARS outbreak in a general hospital in Tianjin, China -- the case of super-spreader.

Severe acute respiratory syndrome (SARS) is a newly emerged infectious disease with a high case-fatality rate and devastating socio-economic impact. In this report we summarized the results from an epidemiological investigation of a SARS outbreak in a hospital in Tianjin, between April and May 2003. We collected epidemiological and clinical data on 111 suspect and probable cases of SARS associated with the outbreak. Transmission chain and outbreak clusters were investigated. The outbreak was single sourced and had eight clusters. All SARS cases in the hospital were traced to a single patient who directly infected 33 people. The patients ranged from 16 to 82 years of age (mean age 38.5 years); 38.7% were men. The overall case fatality in the SARS outbreak was 11.7% (13/111). The outbreak lasted around 4 weeks after the index case was identified. SARS is a highly contagious condition associated with substantial case fatality; an outbreak can result from one patient in a relatively short period. However, stringent public health measures seemed to be effective in breaking the disease transmission chain.

Adolescent↗
PubMed2004

High-resolution cDNA microarray CGH mapping of genomic imbalances in osteosarcoma using formalin-fixed paraffin-embedded tissue.

Formalin-fixed paraffin embedded (FFPE) tumor tissue provides an opportunity to perform retrospective genomic studies of tumors in which chromosomal imbalances are strongly associated with oncogenesis. The application of comparative genomic hybridization (CGH) has led to the rapid accumulation of cytogenetic information on osteosarcoma (OS); however, the limited resolving power of metaphase CGH does not permit precise mapping of imbalances. Array CGH allows quantitative detection and more precise delineation of copy number aberrations in tumors. Unfortunately the high cost and lower density of BACs on available commercial arrays has limited the ability to comprehensively profile copy number changes in tumors such as OS that are recurrently subject to genomic imbalance. In this study a cDNA/EST microarray including 18,980 human cDNAs (which represent all 22 pairs of autosomal chromosomes and chromosome X) was used for CGH analysis of eight OS FFPE. Chromosomes 1, 12, 17, and X harbored the most imbalances. Gain/amplification of X was observed in 4/8 OS, and in keeping with other recent genomic analyses of OS, gain/amplification of 17p11.2 was often accompanied by a distal deletion in the region of the p53 gene. Gain/amplification of the X chromosome was verified using interphase FISH carried out on a subset of OS FFPE sections and OS tissue arrays.

Adolescent↗
PubMed2001

Modifications in surgical implantation of the Penn State electric total artificial heart.

BACKGROUND: Two modifications of the surgical implantation protocol for the Penn State Total Artificial Heart (ETAH) were evaluated: Phrenic nerve ischemia was prevented by minimizing dissection and traction; and hemostasis was augmented and ETAH cuff anastomoses reinforced by using fibrin glue. METHODS: Thirteen Holstein calves underwent orthotopic surgical implantation of the Penn State ETAH between February 1998 and August 2000. Mean hemodynamic and laboratory chemistry variables from the first postoperative week were compared between calves receiving the original (n = 7) and modified (n = 6) protocol. RESULTS: Calves assigned to the modified protocol displayed an improvement in the Po2/FiO2 ratio compared to original (419.4 +/- 17.5 vs 336.3 +/- 35.4, respectively; p = 0.05). All additional parameters were equivalent between groups. The percent survival of animals receiving the modified protocol at 2, 4, and 12 weeks was higher than that of animals that underwent the original protocol. Original-protocol calf deaths consisting of hemothorax (n = 3), and respiratory failure (n = 1) were prevented in the modified protocol. CONCLUSIONS: Our results suggest that manipulations in surgical protocol may promote increased survival in calves implanted with the Penn State ETAH.

Animals↗
PubMed2001

Validating a model of patient satisfaction with emergency care.

STUDY OBJECTIVE: We sought to validate a previously developed model of emergency department patient satisfaction in a general population using a standard mailed format. The study aims to export the findings of a comprehensive ED quality-of-care study to an easily measured patient population. METHODS: A double-sided, single-page survey was mailed to all patients discharged home from 4 teaching hospital EDs during a 1-month period. Determinants of patient satisfaction were analyzed with a previously developed multivariate, ordinal logistic-regression model. RESULTS: The mail survey response rate was 22.9% (2,373/10,381). The survey validates the importance of previously identified determinants of patient satisfaction, including age, help not received when needed, poor explanation of problem, not told about wait time, not told when to resume normal activity, poor explanation of test results, and not told when to return to the ED (P <.01). Greater age predicted higher patient satisfaction, whereas all other variables correlated with lower patient satisfaction. In contrast with prior findings, black race was not a significant predictor of satisfaction in the mail survey population. Low ratings of overall care are strongly correlated with reduced willingness to return (P <.0001). CONCLUSION: A patient satisfaction model was previously developed from a comprehensive research survey of ED care. We demonstrate the generalizability of this model to a mail survey population and replicate the finding that satisfaction strongly predicts willingness to return. The response rate of this study is typical of commercial patient-satisfaction surveys. The validated model suggests that ED patient satisfaction improvement efforts should focus on a limited number of modifiable and easily measured factors.

Adult↗
PubMed2000

Determinants of patient satisfaction and willingness to return with emergency care.

STUDY OBJECTIVE: To identify emergency department process of care measures that are significantly associated with satisfaction and willingness to return. METHODS: Patient satisfaction and willingness to return at 5 urban, teaching hospital EDs were assessed. Baseline questionnaire, chart review, and 10-day follow-up telephone interviews were performed, and 38 process of care measures and 30 patient characteristic were collected for each respondent. Overall satisfaction was modeled with ordinal logistic regression. Willingness to return was modeled with logistic regression. RESULTS: During a 1-month study period, 2,899 (84% of eligible) on-site questionnaires were completed. Telephone interviews were completed by 2,333 patients (80% of patients who completed a questionnaire). Patient-reported problems that were highly correlated with satisfaction included help not received when needed (odds ratio [OR] 0.345; 95% confidence interval [CI] 0.261 to 0.456), poor explanation of causes of problem (OR 0.434; 95% CI 0.345 to 0.546), not told about potential wait time (OR 0.479; 95% CI 0.399 to 0.577), not told when to resume normal activities (OR 0.691; 95% CI 0.531 to 0.901), poor explanation of test results (OR 0.647; 95% CI 0.495 to 0.845), and not told when to return to the ED (OR 0.656; 95% CI 0. 494 to 0.871). Other process of care measures correlated with satisfaction include nonacute triage status (OR 0.701, 95% CI 0.578 to 0.851) and number of treatments in the ED (OR 1.164 per treatment; 95% CI 1.073 to 1.263). Patient characteristics that significantly predicted less satisfaction included younger age and black race. Determinants of willingness to return include poor explanation of causes of problem (OR 0.328; 95% CI 0.217 to 0.495), unable to leave a message for family (OR 0.391; 95% CI 0.226 to 0. 677), not told about potential wait time (OR 0.561; 95% CI 0.381 to 0.825), poor explanation of test results (OR 0.541; 95% CI 0.347 to 0.846), and help not received when needed (OR 0.537; 95% CI 0.340 to 0.846). Patients with a chief complaint of hand laceration were less willing to return compared with a reference population of patients with abdominal pain. Willingness to return is strongly predicted by overall satisfaction (OR 2.601; 95% CI 2.292 to 2.951). CONCLUSION: These data identify specific process of care measures that are determinants of patient satisfaction and willingness to return. Efforts to increase patient satisfaction and willingness to return should focus on improving ED performance on these identified process measures.

Adolescent↗
PubMed1999

Bridge to transplantation: the Penn State experience.

BACKGROUND: During the past decade, ventricular assist devices as a bridge to transplantation have moved from the experimental arena to accepted therapy. Our institution has been at the forefront of the development of this technology and consequently has had extensive experience with the devices that are currently approved by the Food and Drug Administration for use as a bridge to heart transplantation. METHODS: The successful management of patients with assist devices hinges on patient and device selection as well as perioperative management strategies. The routine use of agents such as aprotinin, vasopressin, milrinone, and inhaled nitric oxide has contributed to successful management of these patients. We present our perspectives on the advantages and disadvantages of the Thermo-Cardiosystems HeartMate 1000 IP device and the Thoratec (Pierce-Donachy) system. We also discuss our protocols and methods for patient selection, preoperative preparation, intraoperative strategy, and postoperative management that have resulted in improved patient outcomes. RESULTS: More than 60 device implantation procedures have been performed since the inception of our bridge to transplantation program. During this time, two thirds of our patients were successfully bridged to transplantation. Of these patients, 92% were alive at 1 month after transplantation, and 83% were alive at 1 year after transplantation. CONCLUSIONS: Both support systems are effective in supporting patients to heart transplantation. We have developed a preference for the Thermo-Cardiosystems HeartMate 1000 IP device because of its portability and associated better quality of life. However, the Thoratec device is the more versatile device, and circumstances exist when its use is clearly advantageous. In our institutional experience, outcome for bridging to transplantation has not been device dependent.

Equipment Design↗
PubMed1999

100 long-term implantable left ventricular assist devices: the Columbia Presbyterian interim experience.

BACKGROUND: The use of left ventricular assist devices (LVADs) as bridge to transplantation is now accepted as a standard of care for a subset of end-stage heart failure patients. Our interim experience with both pneumatically and electrically powered ThermoCardiosystems LVADs is presented to outline the benefits and limitations of device support as well as discuss its potential role as bridge to recovery and as destination therapy. METHODS AND RESULTS: Detailed records were kept prospectively for all patients undergoing LVAD insertion. One hundred LVADs were inserted over 7 years into 95 patients, with an overall survival rate of 75% and a transplantation rate of 70%. Four patients underwent device explant for recovered myocardial function. Three patients received LVADs as destination therapy in the ongoing REMATCH (Randomized Evaluation of Mechanical Assist Treatment for Congestive Heart failure) trial. Overall mean patient age was 51 years, and mean duration of support was 108 days. There were 25 device-related infections including the drive line, device pocket, and blood-contacting surfaces. Cerebral vascular accidents and other embolic events occurred in 7 patients with six deaths. There were four device malfunctions and nine graft-related hemorrhages, resulting in six reoperations and three deaths. CONCLUSIONS: The use of long-term implantable LVADs will likely not be limited to bridge to transplantation. The REMATCH trial has commenced to study the role LVADs may have as an alternative to medical management. Furthermore, as the issues of myocardial recovery are examined, the "bridge to recovery" may be an important additional role for these assist devices.

Cause of Death↗
PubMed1998

Endometrial responsiveness to oxytocin during diestrus and early pregnancy in pigs is not controlled solely by changes in oxytocin receptor population density.

These studies were performed to test the hypotheses that: 1) endometrial responsiveness to oxytocin (OT) in pig endometrium is associated with changes in OT receptor (OTr) population density resulting from corresponding regulation of OTr gene transcription, 2) endometrial responsiveness to OT is controlled solely through a mechanism involving changes in OTr population density, and 3) OTr population density and endometrial responsiveness to OT differ between diestrus and early pregnancy in pigs. In experiment 1, OTr population density and dissociation constant (Kd) in cyclic pigs were constant on Days 10-16 but increased (p < 0.05) between Days 10 and 12 of pregnancy before decreasing (p < 0.05) through Day 16. OT induced phosphoinositide (PI) hydrolysis and prostaglandin (PG) F2 alpha secretion in cyclic pigs only on Day 16 (p < 0.05), and during pregnancy only on Day 12 (p < 0.05). Activation of G protein by aluminum fluoride (AIF4-) treatment maximally stimulated (p < 0.05) PI hydrolysis and PGF2 alpha secretion in cyclic pigs on all days, indicating that downstream from the OTr, the PGF2 alpha secretory pathway was fully functional. During pregnancy, PI hydrolysis and PGF2 alpha secretion in response to AIF4- decreased (p < 0.01) on Days 14 compared to Days 10 and 12, and AIF4- did not stimulate PGF2 alpha release on Day 16. In experiment 2, abundance of OTr mRNA in cyclic pigs decreased between Days 0 and 5 before increasing between Days 5 and 12 (p < 0.05), but it was higher (p < 0.05) on Days 10-15 of pregnancy than on equivalent days in cyclic gilts. These results indicate that control of PGF2 alpha secretion in cyclic pigs appeared to occur primarily at the level of OTr coupling to G protein because changes in OTr number were not associated with increased sensitivity to OT or G-protein activation by AIF4-. During pregnancy, control was exerted at multiple levels, which included the OTr, G protein, phospholipase C, and subsequent aspects of the secretory pathway. The present study also indicated that endometrium was responsive to OT during luteolysis in cyclic pigs but not during corpus luteum maintenance in pregnant pigs.

Aluminum Compounds↗
PubMed1997

Functional roles of dopamine D2 and D3 autoreceptors on nigrostriatal neurons analyzed by antisense knockdown in vivo.

Two different 19-mer antisense oligodeoxynucleotides complementary to the initial coding regions of dopamine D2 or D3 receptor mRNA were infused unilaterally into the substantia nigra of rats for 3-6 d to suppress synthesis of D2 and/or D3 receptors on substantia nigra dopaminergic neurons, thereby producing specific reductions of D2 and/or D3 receptors. Autoradiographic receptor binding revealed that D2 and D3 antisense oligodeoxynucleotides specifically and significantly reduced D2 or D3 binding in the ipsilateral substantia nigra, respectively, without affecting dopamine receptor binding in the neostriatum. Either D2 or D3 antisense oligodeoxynucleotides greatly attenuated the ability of apomorphine to inhibit dopaminergic neurons in vivo, an effect that was potentiated by simultaneous administration of D2 and D3 antisenses. Despite these effects, neither the rate nor the pattern of spontaneous activity of antisense-treated nigrostriatal neurons differed from those in the control groups. The proportion of antidromic responses consisting of full spikes from antisense-treated rats was significantly greater, and the mean antidromic threshold was significantly lower than in controls, indicating that autoreceptor knockdown increased both somatodendritic and terminal excitability. These data demonstrate that selective reduction of specific dopamine receptor subtypes by antisense infusion can be effected in vivo, and that nigrostriatal neurons express both D2 and D3 autoreceptors at their somatodendritic and axon terminal regions. Although the somatodendritic and terminal autoreceptors modulate dendritic and terminal excitability, respectively, the interaction of endogenously released dopamine with somatodendritic autoreceptors does not appear to exert a significant effect on spontaneous activity in anesthetized rats.

Animals↗
PubMed1997

Improved results for postcardiotomy cardiogenic shock with the use of implantable left ventricular assist devices.

BACKGROUND: Over the past decade, the use of mechanical circulatory support in patients with postcardiotomy cardiogenic shock has resulted in hospital discharge rates of 25% to 40%. In an attempt to improve patient survival, we initiated a program of early insertion of an implantable Thermocardiosystems Incorporated Heartmate left ventricular assist device in patients who have circulatory failure after having undergone high-risk cardiac operations. METHODS: Between April 1993 and February 1997, 12 patients underwent insertion of an implantable left ventricular assist device for postcardiotomy cardiogenic shock after coronary artery bypass grafting. Indications for insertion included postoperative cardiogenic shock (7 patients), postoperative cardiac arrest (3 patients), and failure to wean from cardiopulmonary bypass (2 patients). RESULTS: The median time to device insertion was 3.5 days. The mean duration of left ventricular assist device support was 103 +/- 19 days (range, 2 to 225 days). Nine of 11 patients (82%) survived to undergo either transplantation (8 patients) or explantation (1 patient), with successful hospital discharge of all 9 patients. The major complication was device-related infection (42%). A single thromboembolism occurred in a patient with an infection. CONCLUSIONS: Long-term outcome after postcardiotomy cardiogenic shock is improved substantially with the use of an implantable left ventricular assist device early in the postoperative course. Access to such a device is an important consideration before undertaking a high-risk cardiac operation, and early implantation of the device is a critical factor in ensuring long-term survival.

Algorithms↗
PubMed1997

Implantable left ventricular assist devices provide an excellent outpatient bridge to transplantation and recovery.

OBJECTIVES: Our recent experience with outpatient left ventricular assist device (LVAD) support is presented to demonstrate the possibilities and limitations of long-term outpatient mechanical circulatory assistance. BACKGROUND: The experience with inpatient LVAD support as a bridge to transplantation has proved the efficacy of such therapy in improving circulatory hemodynamic status, restoring normal end-organ function and facilitating patient rehabilitation. With miniaturization of the power supplies and controllers, such mechanical circulatory support can now be accomplished in an outpatient setting. METHODS: Between March 1993 and February 1997, 32 patients (26 male, 6 female, mean [+/-SEM] age 49 +/- 15 years) underwent implantation of the ThermoCardiosystems (TCI) Heartmate vented electric (VE) LVAD. The VE LVAD is powered by batteries worn on shoulder holsters and is operated by a belt-mounted system controller, allowing unrestricted patient ambulation and hospital discharge. RESULTS: Mean duration of support was 122 +/- 26 days (range 3 to 605), with a survival rate to transplantation or explantation of 78%. Nineteen patients were discharged from the hospital on mean postoperative day 41 +/- 4 (range 17 to 68), for an outpatient support time of 108 +/- 30 days (range 2 to 466). Four patients underwent early transplantation and could not participate in the discharge program, and three patients currently await discharge. The complication rate was not statistically different from that encountered in our previous 52 patients with a pneumatic LVAD. CONCLUSIONS: Outpatient LVAD support is safe and provides improved quality of life for patients awaiting transplantation. Wearable and totally implantable LVADs should be studied as permanent treatment options for patients who are not candidates for heart transplantation.

Ambulatory Care↗
PubMed1997

Vesicular transport regulates monoamine storage and release but is not essential for amphetamine action.

To assess the role of exocytotic release in signaling by monoamines, we have disrupted the neuronal vesicular monoamine transporter 2 (VMAT2) gene. VMAT2-/- mice move little, feed poorly, and die within a few days after birth. Monoamine cell groups and their projections are indistinguishable from those of wild-type littermates, but the brains of mutant mice show a drastic reduction in monoamines. Using midbrain cultures from the mutant animals, amphetamine but not depolarization induces dopamine release. In vivo, amphetamine increases movement, promotes feeding, and prolongs the survival of VMAT2-/- animals, indicating that precise, temporally regulated exocytotic release of monoamine is not required for certain complex behaviors. In addition, the brains of VMAT2 heterozygotes contain substantially lower monoamine levels than those of wild-type littermates, and depolarization induces less dopamine release from heterozygous than from wild-type cultures, suggesting that VMAT2 expression regulates monoamine storage and release.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Implantable left ventricular assist devices: an evolving long-term cardiac replacement therapy.

OBJECTIVE: The authors' 8-year experience with both inpatient and outpatient left ventricular assist device (LVAD) support is presented to show the possibilities and limitations of long-term outpatient mechanical circulatory assistance. SUMMARY BACKGROUND DATA: The limitation of suitable cardiac donors has led to the use of LVADs as a temporizing measure for patients awaiting cardiac transplantation. The success of such devices in the short and medium term as a bridge to transplantation has led to their evaluation as a long-term destination therapy for end-stage heart disease. METHODS: Between August 1990 and February 1997, 85 patients with end-stage heart disease underwent insertion of implantable LVADs. Fifty-two patients underwent pneumatic device insertion and 32 patients received a vented electric device. RESULTS: Patients were supported for a mean of 109+/-13 days for an overall survival to transplant (54) or explant (3) of 73%. Nineteen patients were discharged from the hospital on a mean of postoperative day 41+/-4 (range, 17-68) for an outpatient support time of 108+/-30 days (range, 2-466). Of 12 patients supported after postcardiotomy cardiogenic shock, 10 (82%) survived to hospital discharge. Perioperative right ventricular failure was treated in most patients with inotropic agents and inhaled nitric oxide with only six patients requiring right ventricular assist device support. Thromboembolic rate was low (0.016 events/patient-month) despite minimal or no anticoagulation in all cases. CONCLUSIONS: Left ventricular assist device support has evolved to become an outpatient therapy with excellent survival rates and an acceptable morbidity. Accordingly, wearable LVADs should be studied as permanent treatment options for patients who are not transplant candidates.

Ambulatory Care↗
PubMed1997

The role of the active site cysteine in catalysis by type 1 iodothyronine deiodinase.

Type 1 iodothyronine deiodinase (deiodinase 1) is a selenoenzyme that converts the prohormone T4 to the active thyroid hormone T3 by outer ring deiodination or to the inactive metabolite rT3 by inner ring deiodination. Although selenocysteine has been demonstrated to be essential for the biochemical profile of deiodinase 1, the role of a highly conserved, active site cysteine (C124 in rat deiodinase 1) has not been defined. The present studies examined the effects of a Cys124Ala mutation on rat deiodinase 1 enzymatic function and substrate affinity. At a constant 10-mM concentration of dithiothreitol (DTT), the C124A mutant demonstrated a 2-fold lower apparent maximal velocity (Vmax) and Km for rT3 (KmrT3) than the wild type for outer ring deiodination, whereas the Vmax/Km ratio was unchanged. Similarly, the apparent Vmax and KmT3 sulfate for inner ring deiodination were 2-fold lower in the C124A mutant relative to those in the wild type, with no change in the Vmax/Km ratio. The C124A mutant exhibited ping-pong kinetics in the presence of DTT, and substitution of the active site cysteine increased the KmDTT by 14-fold relative to that of the wild-type enzyme, with no significant effects on KmrT3 or Vmax. The C124A mutant was inhibited by propylthiouracil in an uncompetitive fashion and exhibited a 2-fold increase in K(i)propylthiouracil compared with that of the wild type. KmrT3 was also reduced for the C124A mutant when 5 mM reduced glutathione, a potential physiological monothiol cosubstrate, was used in outer ring deiodination assays. These results demonstrate that thiol cosubstrate interactions with C124 in type 1 deiodinase play an important role in enhancing catalytic efficiency for both outer and inner ring deiodination.

Amino Acid Sequence↗
PubMed1996

D1 dopamine receptor stimulation inhibits firing activity of midbrain dopamine neurons in reserpine treated rats: an effect eliminated after hemitransection of diencephalon.

It has been reported that systemic administration of the D1 dopamine (DA) receptor agonist SKF 38393 inhibits the firing rate of substantia nigra pars compacta (SNC, A9) DA neurons after repeated reserpine treatment in locally anesthetized rats, although SKF 38393 induces little effect on the firing of midbrain DA neurons in normal rats. The present study found that local pressure microejection of SKF 38393 (10(-2) M, 20-100 nl) to SNC or substantia nigra pars reticulata (SNR) failed to influence the firing of SNC DA neurons in reserpinized rats (reserpine 1 mg/kg x 6 days, s.c.); subsequent intravenous (i.v.) injection of SKF 38393 (4 mg/kg), however, inhibited their firing and the inhibition was reversed by the D1 receptor antagonist SCH 23390. Similarly, systemic administration of SKF 38393 (4 mg/kg, i.v.) inhibited the firing of ventral tegmental area (VTA, A10) DA cells in reserpinized rats, while local microejection of SKF 38393 (10(-2) M, 30-60 nl) did not affect their firing. Furthermore, the inhibitory effect of systemic SKF 38393 on firing rate of either SNC or VTA DA neurons in reserpinized rats was eliminated after hemitransection of diencephalon. These results suggest that repeated reserpine treatment renders midbrain DA neurons responsive to D1 receptor stimulation and that D1 receptor agonist-induced inhibition of midbrain DA cell firing in reserpinized rats may require the involvement of long-loop feedback pathways.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1996

(-)-Stepholidine acts as a D1 partial agonist on firing activity of substantia nigra pars reticulata neurons in 6-hydroxydopamine-lesioned rats.

(-)-Stepholidine (SPD), a novel dopamine (DA) D1 and/or D2 receptor antagonist in normosensitive animals, shows agonistic effects on D1 receptors in rotational behavior of 6-hydroxydopamine (6-OHDA)-lesioned rats. To further characterize the pharmacological properties of SPD, we investigated the effects of SPD on firing activity of substantia nigra pars reticulata (SNR) neurons in different sensitive models. In control rats, the selective D1 agonist SKF38393 (4 mg/kg, i.v.) induced inconsistent changes (i.e. increase, decrease or no change) in firing of SNR neurons. These effects were completely antagonized by SPD (i.v.), regardless of the changes induced by SKF38393. SPD (4 mg/kg), per se, increased firing by 30.9 +/- 14.4%. In reserpinized rats, SKF38393 also induced SPD-reversible inconsistent changes as in control rats. Nevertheless, SPD per se produced no alteration in firing of SNR neurons. In 6-OHDA-lesioned rats, 5/6 SNR neurons were inhibited by SKF38393. The inhibition was completely abolished by Sch23390, a selective D1 antagonist (0.5-2 mg/kg), but partially reversed by SPD (1-16 mg/kg). Moreover, SPD (4 mg/kg) itself caused SNR increased or decreased neuron firing, and these effects were completely reversed by Sch23390 (0.5-2 mg/kg) in 8/12 neurons recorded. These results suggest that SPD acts as a partial agonist to D1 receptors in 6-OHDA-lesioned rats, but as an antagonist to D1 receptors in normal and reserpinized rats.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗