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Biomedical subjects

L Gong

Publications and source records attributed to L Gong.

At least 91 records · Page 5Linked to original sources
PubMed1993

Dose-related effects of a neonatal 6-OHDA lesion on SKF 38393- and m-chlorophenylpiperazine-induced oral activity responses of rats.

Neonatal 6-hydroxydopamine (6-OHDA) treatment of rats is associated with concurrent supersensitization of dopamine (DA) D1 and serotonin 5-HT1C receptors, for agonist-induced oral activity. The present study was conducted to determine if graded reduction of striatal DA content and/or graded elevation of striatal 5-HT content by 6-OHDA would alter sensitivity of either receptor type, and thereby influence oral activity responses to DA and 5-HT agonists. At 3 days after birth, groups of rats were pretreated with desipramine (20 mg/kg i.p.), 1 h before administration of a range of doses of 6-OHDA HBr (15, 30, 60, 100, 150 and 200 micrograms, i.c.v., salt form; half in each lateral ventricle) or the vehicle, saline (0.85%)-ascorbic acid (0.1%). Between 2 and 4 months, a series of challenge doses of SKF 38393 HCl (0.30 to 3.0 mg/kg i.p.) and m-chlorophenylpiperazine 2HCl (0.30 to 6.0 mg/kg i.p.; m-CPP 2HCl) were administered to each group of rats and oral activity was observed. Oral activity was determined for 1 min every 10 min during a 60-min period, starting 10 min after injection of agonist or vehicle. SKF 38393 dose-response curves demonstrated enhanced oral activity responses in rats lesioned neonatally with 150 or 200 micrograms of 6-OHDA. m-CPP dose-response curves demonstrated enhanced oral activity responses in these 2 groups of rats, as well as those lesioned neonatally with 100 micrograms of 6-OHDA. Striatal DA content was reduced by > 97% in these 3 groups of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1993

Ontogenetic SKF 38393 treatments sensitize dopamine D1 receptors in neonatal 6-OHDA-lesioned rats.

Neonatal 6-hydroxydopamine (6-OHDA) treatment of rats is associated with supersensitization of the dopamine (DA) D1 agonist induction of stereotyped and locomotor behaviors. The present study was conducted to determine whether ontogenetic treatments of these rats with the DA D1 receptor agonist, SKF 38393, would produce a maximal DA D1 receptor supersensitivity, as measured by locomotor behavior in adulthood. Rat pups were treated daily with SKF 38393-HCl (3.0 mg/kg per day, i.p.) or saline vehicle for 28 consecutive days from birth. These animals were additionally treated at 3 days after birth with 6-OHDA-HBr (100 micrograms, in each lateral ventricle, salt form) or its vehicle. Between 6 and 9 weeks locomotor activity or stereotyped behaviors were observed after weekly challenge doses of SKF 38393-HCl (3.0 mg/kg, i.p.). In the neonatal 6-OHDA group, successive SKF 38393 treatments produced progressively greater locomotor activity. In the group of rats treated during postnatal ontogeny with both 6-OHDA and SKF 38393 daily treatments, the first adult challenge dose of SKF 38393 produced an enhanced locomotor response, greater than that seen in other groups (P < 0.01). Subsequent SKF 38393 treatments of this group produced increasingly greater locomotor responses. SKF 38393-induced stereotyped behavioral effects were greater in the 6-OHDA-lesioned groups, whether or not SKF 38393 was administered ontogenetically. Profound reductions (> 99%) of DA and its metabolites were found in the striatum of neonatal 6-OHDA treated rats, regardless of whether SKF 38393 was co-administered ontogenetically.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1993

Atrial fibrillation and coronary artery disease.

A retrospective study of the incidence of atrial fibrillation in 703 consecutive patients who had undergone selective coronary arteriography and left ventricular catheterization between November 1986 and May 1992 was undertaken. The study group included 136 patients with significant coronary stenosis (> 50% diameter reduction) without previous myocardial infarction (group I), 157 with a history of myocardial infarction (group II), 326 with chest pain and normal coronary angiography (group III), 72 with valvular disease (group IV), and 12 with cardiomyopathy (group V). Clinical and electrocardiographic evidence of atrial fibrillation was documented in 75 patients (10.7%), including 2 (1.5%) in group I, 6 (3.8%) in group II, 36 (11%) in group III, 27 (37.5%) in group IV, and 4 (33.3%) in group V. The rate of occurrence of atrial fibrillation was lower in groups I and II than in groups III, IV and V. Atrial fibrillation was rarely found in coronary artery disease.

Aged↗
PubMed1993

Serotonin (5-HT) systems mediate dopamine (DA) receptor supersensitivity.

To study interactions between DA and 5-HT neurochemical systems in the DA D1 supersensitized induction of oral activity in neonatal 6-hydroxydopamine (6-OHDA) lesioned rats, the effects of a variety of 5-HT receptor agonists and antagonists were determined. At 3 days after birth rats were treated with desipramine HCl (20 mg/kg i.p., base form) 1 h before 6-OHDA HBr (100 micrograms, salt form, in each lateral ventricle). When these rats were studied as adults it was determined that the striatal content of DA, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) was reduced by 98%, while the striatal content of 5-HT was elevated by 75%. The Bmax and Kd for [3H]SCH 23390 and [3H]spiperone binding to striatal homogenates was unaltered in the lesioned rats. However, oral activity responses to a D1 agonist (SKF 38393), D2 antagonist (spiperone) and 5-HT1C agonist [1-(3-chlorophenyl)piperazine] were enhanced several fold in the lesioned rats. Several other agonists and antagonists that act at 5-HT1A, 5-HT1B, 5-HT2 and 5-HT3 receptors did not produce an altered response in the lesioned rats, nor were these substances effective in attenuating m-CPP-enhanced oral activity responses. The DA D1 receptor antagonist, SCH 23390 HCl (0.30 mg/kg i.p.), did not attenuate the response to m-CPP 2HCl (1.0 mg/kg i.p.). However, the 5-HT receptor antagonist, mianserin HCl (1.0 mg/kg s.c.) did effectively attenuate the oral activity response to SKF 38393 HCl (1.0 mg/kg i.p.). These findings indicate that there is supersensitization of both DA D1 and 5-HT1C receptors in neonatal 6-OHDA-lesioned rats, and that a D1 agonist acts via the 5-HT1C receptors. Therefore, induction of oral activity by DA agonists occurs through a serotoninergic neurochemical system.

Animals↗
PubMed1992

Supersensitized oral responses to a serotonin agonist in neonatal 6-OHDA-treated rats.

Neonatal 6-hydroxydopamine (6-OHDA) treatment of rats is associated with supersensitization of the dopamine D1 agonist induction of oral activity. The present study was conducted to determine whether induced oral responses to serotonin (5-HT) agonists would be similarly altered in this rat model. At 3 days after birth, rats received desipramine HCl (20 mg/kg, IP) 1 h before 6-OHDA HBr (100 micrograms in each lateral ventricle) or saline-ascorbic acid (0.1%) vehicle. At approximately 9 mo, rats were challenged with the mixed 5-HT1C and 5-HT2 receptor agonist, m-chlorophenylpiperazine diHCl (m-CPP 2HCl; 0.30-6.0 mg/kg, IP) and were then observed for 1 min every 10 min over a 60-min period. m-CPP induced oral activity in both the vehicle and 6-OHDA groups, with the responses of the 6-OHDA group being much greater. An m-CPP dose of 3.0 mg/kg produced a maximal response of 63.6 +/- 3.2 oral movements in the 6-OHDA group. A bell-shaped response curve was obtained, with lower and higher doses of m-CPP producing less of an effect. Attenuation of the m-CPP-induced response by the 5-HT receptor antagonist, mianserin HCl (1.0 mg/kg, IP, 30 min before m-CPP), indicates that the m-CPP effect is receptor mediated. These findings demonstrate that neonatal 6-OHDA treatment produces ontogenic long-lived supersensitization of a 5-HT receptor system in rats.

Animals↗
PubMed1992

Effects of MPTP and vitamin E treatments on immune function in mice.

The effects of treatment with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and vitamin E, an antioxidant, on immune functions were examined. Male C57/B1 mice were fed daily with natural vitamin E for 12 weeks, subsequently injected i.p. with MPTP or its vehicle, and sacrificed 1 week later. Control mice received the stripped corn oil vehicle daily, in place of vitamin E. Oral vitamin E feeding increased cerebral vitamin E content by 60% (P = 0.05). However, MPTP attenuated this rise in cerebral vitamin E content when measured 1 week after treatment with the neurotoxin (P = 0.05). MPTP also produced an 80-90% reduction in striatal dopamine content in both the stripped corn oil control group and the vitamin E-treated group (P = 0.0000). One week after MPTP injection, the numbers of peripheral blood lymphocytes and the percent of spleen T-cells, but not B-cells, were decreased in those groups receiving MPTP alone or MPTP plus vitamin E (P less than 0.05 and 0.02, respectively). The Con A-induced IL-2 production of spleen cells was decreased in all treated groups (P less than 0.005). There was no difference in the mitogenic stimulative response to PHA, Con A or LPS. However, the response to PWM was increased in both MPTP and MPTP plus vitamin E-treated groups (P less than 0.05 and 0.001, respectively). On the other hand, the one-way mixed lymphocyte response of the splenocytes from the MPTP-treated group was increased (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Relationship between different patterns of left ventricular hypertrophy and plasma norepinephrine and hemorheology in patients with essential hypertension].

The changes of plasma norepinephrine (NE) concentration and hemorheology in 60 patients with essential hypertension (EH) with different patterns of left ventricular hypertrophy (LVH) were observed. The results showed that a higher value in whole blood viscosity (WBV) at a shear rate of 230-s was found in concentric hypertrophy (CH) group; a significant increase in plasma NE was found in asymmetric septal hypertrophy (ASH) group. It suggests that CH appear to be a compensation adapting to the increase in afterload. Significant increase in plasma NE concentration may play an important role in the development of ASH in addition to the afterload.

Adult↗
PubMed1992

[The characterization of mutant No. 68 from midecamycin producing strain S. mycarofaciens 1748].

A stable mutant No. 68 was obtained by treatment of S. mycarofaciens 1748 spores at high temperature. The electromicroscopic examination has shown that the mutant No. 68 and parent strain 1748 both have the spore chains of the spiratype. The spores of both strain are cylindrical in shape. The only difference is that the spores of the mutant No. 68 are of smooth surface, but the 1748 are of thorny. The physiological characteristics of both strains are also very similar with slight differences in utilization of few carbon sources and in cultural characters in few medium. Feeding experiment has shown that the mutant No. 68 was blocked in the formation of the macrolide lactone in the midecamycin biosynthetic pathway. This suggested that the mutant No. 68 might be a polyketide synthase genes deficient mutant. The ability of the mutant No. 68 to convert spiramycin into 4"-propionylspiramycin indicated that the mutant No. 68 contained the midecamycin 4"-propionyltransferase and could be used for microbial bioconversion of spiramycin into 4"-propionylspiramycin.

Leucomycins↗
PubMed1992

Supersensitization of the oral response to SKF 38393 in neonatal 6-OHDA-lesioned rats is mediated through a serotonin system.

To study possible interactions between dopamine (DA) and serotonin (5-HT) neurochemical systems in the D-1 supersensitized induction of oral activity in neonatal 6-hydroxydopamine (6-OHDA) lesioned rats, the effects of a series of 5-HT agonists and antagonists were determined. At 3 days after birth rats were treated with desipramine HCl (20 mg/kg i.p., base form, 1 hr) and 6-OHDA HBr (100 micrograms, salt form, in each lateral ventricle). Rats were observed individually as adults, once a minute every 10 min over a 1-hr period after challenge with a DA or 5-HT receptor agonist. The respective 5-HT1A and 5-HT1B agonists, (+/-)-8-hydroxydipropylaminotetralin (0.50 mg/kg s.c.) and CGS 12066B maleate (7-trifluoromethyl-4(4-methyl-1-piperazinyl)-pyrrolo[1, 2-alquinoxaline], 1:2 maleate salt; 3.0 mg/kg i.p.), did not increase oral activity. The mixed 5-HT1C and 5-HT2 receptor agonist, m-chlorophenylpiperazine (m-CPP), produced a slight increase in oral activity in control rats and a marked increase in oral activity in 6-OHDA-lesioned rats. In the 6-OHDA group the peak effect of 76.5 +/- 4.1 oral movements occurred with an m-CPP 2-HCl dose of 4.0 mg/kg. Pindolol (1.0 mg/kg i.p.), ketanserin tartrate (5 mg/kg i.p.) and MDL-72222 (3-tropanyl-3,5-dichlorobenzoate; 10 mg/kg s.c.), antagonists with high affinity for 5-HT1A,1B, 5-HT2 and 5-HT3 receptors, respectively, did not attenuate m-CPP actions. However, mianserin HCl (1.0 mg/kg s.c.), an antagonist with high affinity for 5-HT1C and 5-HT2 receptors, attenuated the oral response to m-CPP.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1991

Supersensitized D1 receptors mediate enhanced oral activity after neonatal 6-OHDA.

Enhanced oral responses have been observed in rats that are treated shortly after birth with 6-hydroxydopamine (6-OHDA). A series of studies was conducted to characterize this effect. A dose-response curve demonstrated that the dopamine D1 receptor agonist, SKF 38393, produced a maximal response in 6-OHDA-treated rats at a dose of 0.10 mg/kg (IP). With the D2 receptor antagonist, spiperone, a bell-shaped dose-response curve was seen, with a maximal effect in the 6-OHDA group occurring at 80 micrograms/kg. There were only slight increases in oral activity with different SKF 38393 or spiperone doses in the saline group, indicating that there was an overt supersensitization of D1 receptors in the 6-OHDA-treated rats. The D1 antagonist SCH 23390 (0.30 mg/kg, IP) attenuated the response to both SKF 38393 and spiperone. The oral response to the D2 agonist, quinpirole (0.10 mg/kg, IP) was not preferentially increased in the 6-OHDA group of rats. These findings indicate that the enhanced oral response in neonatal 6-OHDA-treated rats is mediated by supersensitive dopamine D1 receptors. The persistence of the enhanced oral response in 6-OHDA-treated rats at 8 months demonstrates that this sensitization of D1 receptors is a long-lived phenomenon.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1991

Vitamin E supplements fail to protect mice from acute MPTP neurotoxicity.

The effect of chronic treatment with vitamin E (VE) on acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity, as assessed by striatal dopamine (DA) depletion, was studied. Male C57B1/6J mice were fed VE (48 mg kg-1 per day, intragastric) for 4, 8, or 12 weeks prior to administration of MPTP (20 mg kg-1, i.p. x 3, 2 h intervals) or its diluent. Brain VE concentration was increased by exogenous supplements for 12 weeks. Striatal DA content was reduced by 85% to 90% after MPTP in control and VE-treated mice. Mice with elevated cerebral VE were not protected from MPTP toxicity, with DA content as an indicator. In conclusion, these findings indicate that moderate elevation of brain VE is not adequate for protecting DA-containing neurons against the toxic actions of a high dose of MPTP.

Animals↗
PubMed1991

Automatic generation of plans for biomedical image interpretation.

This paper presents a new object-centered, goal-driven planning approach to biomedical image interpretation. We describe here a prototype system which takes advantage of spatial and detectability constraints from an expert-derived model of expected anatomical structures to automatically generate plans for the interpretation of multimodality images.

Artificial Intelligence↗
PubMed1990

[Combined pharmacokinetic--pharmacodynamic model analysis of N-acetyl procainamids following intravenous infusion in rabbits].

The pharmacokinetic and pharmacodynamic profiles of N-acetyl procainamide were analyzed by integrated PK-PD model following intravenous infusion to rabbits. No significant differences between the PK parameters estimated from iv administration and intravenous infusion were found. However, two of the PD parameters were shown to be significantly different. The values of Emax, Keo, S, EC50 were found to be 120 +/- 13.2 ms, 0.0182 +/- 0.007 min-1, 2.26 +/- 0.93, 6.31 +/- 0.71 microgram/ml respectively following intravenous infusion; the corresponding values following iv administration were 53.6 +/- 2.5 ms, 0.061 +/- 0.017 min-1, 2.19 +/- 0.39, 6.21 +/- 1.74 micrograms/ml respectively.

Acecainide↗
PubMed1984

[Interatrial septal aneurysm. Echocardiographic diagnosis].

Interatrial septal aneurysm is a rare abnormality and can now be diagnosed by echocardiography. We report the case of a 52 year old woman in whom this condition was diagnosed after an embolic cerebrovascular accident. M mode recordings showed a linear echo in the left atrial cavity in early and mid systole. The aneurysm was directly visualised by 2D echo as a hemispherical bulge in the mid portion of the interatrial septum, which was mobile and had a to-and-fro motion between the two atria in relation to the different phases of the cardiac cycle. The diagnosis was confirmed by angiography, and at surgery. A feature of this case was the close correlation between echocardiographic, angiographic and operative findings. The pathogenesis of this type of aneurysm remains conjectural as does its role in the production of cerebral embolism, the evidence for which was circumstantial in the absence of other demonstrable causes and in the light of previously reported cases.

Angiography↗
PubMedDate not supplied

MIF-1 fails to modify agonist-induced oral activity in neonatal 6-OHDA-treated rats.

L-Prolyl-L-leucyl-glycinamide (MIF-1) is known to attenuate apomorphine-induced stereotypes in adult rats that are lesioned as neonates with 6-hydroxydopamine (6-OHDA). To test whether MIF-1 would affect dopamine (DA) agonist-induced and serotonin (5-HT) agonist-induced oral activity, both intact and neonatal 6-OHDA-treated rats were studied. Rats at 3 days from birth were injected with desipramine (20 mg/kg, IP), 1 h before 6-OHDA HBr (100 micrograms, salt form, in each lateral ventricle) or its vehicle, saline-ascorbic acid (0.1%). At approximately 6 months rats were treated with MIF-1 (0.1, 1.0, or 10.0 mg/kg, IP), 10 min before SKF 38393 HCl (1.0 mg/kg, IP) or m-chlorophenylpiperazine 2HCl (m-CPP 2HCl; 0.5 mg/kg, IP), DA D1 and 5-HT1C,2 receptor agonists, respectively. Although both agonists increased oral activity in control and neonatal 6-OHDA-treated rats, MIF-1 did not modify the response. In rats that received either of the three doses of MIF-1 for 21 consecutive days, there was still no observed effect of MIF-1 on the oral response of control and 6-OHDA-lesioned rats to SKF 38393 and m-CPP. These findings indicate that MIF-1 does not modify the oral activity response of supersensitized D1 and 5-HT1C receptors in adult rats that are lesioned neonatally with 6-OHDA.

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