[Analysis of the effectiveness of coracoid osteotomy and concentric coaxial reconstruction of the glenoid cavity in the treatment of recurrent anterior dislocation of the shoulder joint]

Objective: To investigate the clinical efficacy of the modified Latarjet procedure in the treatment of recurrent anterior subluxation of the shoulder by "coaxial co-arc" reconstruction of the glenoid cavity. Methods: The clinical data of 103 cases (106 shoulders) of recurrent anterior dislocation of the shoulder admitted to the First Affiliated Hospital of the Army Military Medical University from January 2005 to December 2020 were retrospectively studied. Out of these cases, 84 were males and 19 were females; 31 with left-sided injuries while 75 with right-sided injuries, with a mean age of (29.4±11.5) years (16-61 years). The preoperative anterior fear test was positive, and a modified Latarjet procedure was used to reconstruct the shoulder glenoid defect through a "coaxial co-arc". The Rowe score, simple shoulder test (SST) score, and Visual analogue scale (VAS) score of pain were used to assess the shoulder's function. Parameters such as the postoperative shoulder recurrent dislocation rate, shoulder body external rotation angle, and subscapularis muscle strength changes were recorded postoperatively. Moreover, radiographs and CT scans were used to check for the incidence of osteoarthritis (Samson-Prieto score). Results: After a mean follow-up of 9.0 years (1 to 16 years), bony healing occurred 3 to 6 months postoperatively. The Rowe score improved from 40.4±6.5 preoperatively to 93.2±2.5 (P<0.001), the SST score improved from 5.2±1.3 preoperatively to 10.1±1.5 (P<0.001), and the VAS pain score decreased from 3.5±1.9 preoperatively to 1.1±1.2 (P<0.001) at the final follow-up. The angle of lateral external rotation of the shoulder joint was 58.8°±15.6° preoperatively and 57.6°±14.5° postoperatively with no statistically significant difference (P>0.05). There was no statistically significant difference in the measurement of subscapularis muscle strength between the healthy side and the affected side (P>0.05). In 89.6% of patients after surgery, coaxial co-arc reconstruction of the shoulder glenoid was obtained, and the shoulder glenoid defect and postoperative inclusion angle were significantly improved compared with those before surgery (P<0.001). Postoperatively, new-onset osteoarthritis developed in 7 cases (7/98), arthritis progressed in 2 cases (2/8), incisional healing was poor in 2 cases (2/98), and revision surgery was performed in 2 cases (2/98) due to bone mass detachment. Conclusion: Coracoid osteotomy and concentric coaxial reconstruction of the glenoid cavity elicits adequate good clinical efficacy for cases of recurrent anterior shoulder dislocation, with low recurrence rates, low revision rates and low incidence of osteoarthritis.

[Mid-and-long term follow-up of autogenous tibial periosteum-bone complex transplantation for treatment of cystic osteochondral lesion of talus]

Objective: To further clarify the mid-and-long term follow-up results of self-designed tibial periosteum-bone complex transplantation in the treatment of Hepple V osteochondral lesion of the talus(OLTs). Methods: The clinical data of 30 patients with Hepple V OLTs who received treatment in the Sports Medicine Center of the First Affiliated Hospital of Army Military Medical University from October 2011 to January 2019 were analyzed. There were 19 males and 11 females with a mean age of (40±11) years. Patients were treated with autogenous tibial periosteum-bone complex transplantation and were followed up for at least 2 years. The Foot and Ankle Outcome Score (FAOS), American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, the visual analog scale score (VAS) of pain, the simplified symptomatology evaluation (SSE) and imaging results before the operation and at the follow-up were recorded and compared. Results: The cohort were followed-up for a mean of 63.9 months (range 24-110 months). Twenty-nine (96.7%) patients were satisfied with the curative effect. The FAOS score was improved from 53.5±6.2 preoperatively to 88.4±6.6 at the final follow-up (P<0.001). The AOFAS ankle-hindfoot scale improved from 61.6±8.2 preoperatively to 90.8±6.8 at the last follow-up (P<0.001). The VAS score decreased from 4.3±0.2 preoperative to 0.7±0.7 at the last follow-up (P<0.001). The SSE score was poor in 14 cases (46.7%), average in 16 cases (53.3%) before the operation; and it was excellent in 23 cases (76.7%), good in 6 cases (20%), average in 1 case (3.3%) at the last follow-up. Imaging examination showed cystic change cure rate was 83.3%, cartilage defects were completely infilled with repair tissue, which didn't show any signs of degeneration. However, repair tissue showed varying degrees of heterogeneous signal compared to the normal articular cartilage. Conclusion: The autograft of tibial periosteum-bone complex transplantation is a safe and feasible method for the treatment of osteochondral lesion of the talus in Hepple V type, with good mid-and-long term clinical effect.

[A comparative study of the calcaneal closing-wedge calcaneal osteotomy versus posterior-superior prominence removal in both sides with Haglund syndrome]

Objective: To compare the clinical outcome of removal of calcaneal posterior-superior prominence and that of calcaneal closing-wedge osteotomy for Haglund syndrome. Methods: From February 2009 to July 2014, 36 patients with Haglund syndrome were included.They were divided into two groups, and each group included 18 patients and underwent removal of calcaneal posterior-superior prominence and calcaneal closing-wedge osteotomy respectively.They were evaluated preoperatively and after 6 , 12 months and 24 months postoperatively by American Orthopedic Foot & Ankle Society (AOFAS) score, VAS score, VISA-A questionnaire and Maryland Foot Score.Fowler-Philip angle and calcaneal posterior slope of the two groups were compared preoperatively and after 6 months.All data were analysis utilizing SPSS 18.0. Results: At six months of follow-up, the weight-bearing lateral X-rays reveals that removal of calcaneal posterior-superior prominence did not change Fowler-Philip angle and calcaneal posterior slope and calcaneal closing-wedge osteotomy decreased Fowler-Philip angle and calcaneal posterior slope significantly[from preoperation (56.5±5.4)°, (120.0±1.3)°to postoperation (48.4±4.6)°, (109.0±5.3)°]. At six months of follow-up, the AOFAS score, VAS score, VISA-A questionnaire and Maryland Foot Score were worse in the wedge calcaneal osteotomy group.At twelve months of follow-up, no significant difference (P>0.05)was found between the two groups in terms of VAS score, and Maryland Foot Score, while the AOFAS score, and VISA-A questionnaire in the wedge calcaneal osteotomy group were better than those of posterior-superior prominence removal group.At twenty-four months of follow-up, the AOFAS score, VAS score, VISA-A questionnaire and Maryland Foot Score were better in the wedge calcaneal osteotomy group (P<0.05). Conclusions: Both the two surgical methods are effective for Haglund syndrome.Calcaneal closing-wedge osteotomy decreased Fowler-Philip angle and calcaneal posterior slope of calcaneus and its clinical outcome appears better than that removal of calcaneal posterior-superior prominence.

The safety and effectiveness of TM81, a Chinese herbal medicine, in the treatment of type 2 diabetes: a randomized double-blind placebo-controlled trial

AIM

TM81 (or Tang-Min-Ling-Wan) is a Chinese medicine. Previous studies suggested that this medicine is effective for treating type 2 diabetes. This controlled trial evaluated the safety and effectiveness of TM81 in the treatment of type 2 diabetic patients.

METHODS

This study was a large-scale controlled clinical trial to evaluate the safety and effectiveness of TM81 on type 2 diabetes. After a 2-week run-in period, 480 overweight type 2 early-stage diabetic patients [35-65 years old, HbA1c ≥ 7.0%, fasting plasma glucose (FPG) 7.0-13.9 mM or 2 h plasma glucose (PG) > 11.1 mM, body mass index (BMI) ≥ 24 kg/m(2)] were enrolled. These patients were divided into a TM81 group and placebo group in a 3 : 1 ratio. The subjects received 6 g TM81 or placebo, three times daily for 12 weeks.

RESULTS

After treatment, the HbA1c decrease was 1.02% in the TM81 group versus 0.47% in the placebo group. The FPG decreased 0.8 ± 0.1 mM in the TM81 group versus an increase of 0.2 ± 0.2 mM in the placebo group. The PG decreased 2.7 ± 0.3 mM in the TM81 group versus a decrease of 0.9 ± 0.4 mM in the placebo group (all p < 0.05). The TM81 was more effective for patients with higher baseline HbA1c levels. The TM81 group also showed improved β-cell function and increased homeostatic model assessment (HOMA)-β. In addition, body weight, BMI and waist circumference of subjects in the TM81 group were reduced, and the symptoms related to diabetes were improved. There were no significant differences in the types and frequency of adverse reactions between the two groups.

CONCLUSIONS

The data showed that TM81 is effective in controlling blood glucose level and is safe to use in patients with early-stage type 2 diabetes.

American ginseng berry juice intake reduces blood glucose and body weight in ob/ob mice

Diabetes is a serious chronic metabolic disease and has a significant impact on patients' lives and the health care system. We previously observed that the organic solvent extract of American ginseng berry possessed significant antidiabetic effects in obese diabetic ob/ob mice after intraperitoneal injection. If American ginseng berry is useful as a dietary supplement, simple preparation and oral intake would be a convenient, safe, and practical means for consumers. In this study, the simply prepared berry juice was first analyzed using high-performance liquid chromatography, and then administered orally in the ob/ob mice. The animals received daily berry juice 0.6 mL/kg or vehicle for 10 consecutive days. The results indicated that oral juice administration significantly lowered fasting blood glucose levels, and this effect continued for at least 10 d after cessation of the treatment. Data from intraperitoneal glucose tolerance test demonstrated that there was a notable improvement in glucose tolerance in the juice treated group. In addition, the berry juice significantly reduced body weight. Our data suggest that ginseng berry juice, as a dietary supplement, may have functional efficacy in consumers with diabetes.

Simultaneous identification of Bulbus Fritillariae cirrhosae using PCR-RFLP analysis

Bulbus Fritillariae (BF) is the most commonly used antitussive herb in China. There are nine species of Fritillaria recorded as the drug BF in the Chinese Pharmacopoeia. Bulbus Fritillariae cirrhosae (BF cirrhosae) is a group that includes four species of BF; these four species come from wild sources with higher efficiency and lower toxicity compared to the other five species of BF. Due to reasons of carelessness and reduced costs, the other five species are often sold as BF cirrhosae. Analysis through appearance, microscopic and chemical techniques has limitations. Identifying botanical resources is a primary step in the standardization of herbal medicine. In the present article, the internal transcribed spacer 1 (ITS1) regions of the nuclear ribosomal DNA (nrDNA) of nine species and one variety of Fritillaria genus have been sequenced. A mutation site in the ITS1 region among BF cirrhosae and other species of BF has been found and can be recognized by the restriction endonuclease SmaI. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the nuclear ribosomal ITS1 region was used to differentiate BF cirrhosae from other species of BF and is a successful method in distinguishing the subgroups.

Ganoderma lucidum extract inhibits proliferation of SW 480 human colorectal cancer cells

AIM

Ganoderma lucidum is a commonly used Chinese herb and an important ingredient in traditional Chinese medicine herbal formulations for immune dysfunction related illnesses. The effects of this medicinal mushroom on human colorectal cancer cells have not yet been evaluated. In this study, we investigated the effects of Ganoderma lucidum extract using SW 480 human colorectal cancer cell line.

MATERIALS AND METHODS

Two different fractions of Ganoderma lucidum extract, i.e., a fraction containing mainly polysaccharides (GLE-1), and a triterpenoid fraction without polysaccharides (GLE-2) were analyzed. Their antiproliferative activity was evaluated by cell proliferation assay and 3H-thymidine incorporation assay. Scavenging effects of DPPH radical were assessed using ESR-spectroscopy.

RESULTS

Our data showed that both GLE-1 and GLE-2 significantly inhibited the proliferation of SW 480 cells. The inhibitory effect of GLE-2 was much stronger than that of GLE-1. GLE-1 inhibited DNA synthesis in the cells and reduced the formation of DPPH radicals.

CONCLUSION

Ganoderma lucidum extract inhibits proliferation of human colorectal cancer cells and possesses antioxidant properties.

Crystallization and preliminary X-ray analysis of human placental S-adenosylhomocysteine hydrolase

A recombinant form of human placental S-adenosylhomocysteine (AdoHcy) hydrolase expressed in E. coli, which was inactivated by a type-I mechanism-based inhibitor, has been crystallized using the hanging-drop vapour-diffusion technique. The crystals grow as flat plates, with unit-cell dimensions a = 96.2, b = 173.6, c = 142.9 A, alpha = beta = gamma = 90 degrees. The crystals exhibit the symmetry of space group C222 and diffract to a minimum spacing of approximately 2.0 A resolution at the Cornell High Energy Synchrotron Source. On the basis of density calculations two monomers of the tetrameric protein are estimated to be present in the asymmetric unit (V(m) = 2.99 A(3) Da(-l)). The self-rotation function clearly indicates the location of the non-crystallographic twofold axis.

Anti-hyperglycemic effect of the polysaccharides fraction from American ginseng berry extract in ob/ob mice

In this study, we evaluated the anti-hyperglycemic effect of a polysaccharides fraction from American ginseng berry extract in diabetic ob/ob mice. All animals received daily intraperitoneal injections of polysaccharides at 150 mg/kg body wt. (n = 5), polysaccharides at 50 mg/kg body wt. (n = 5), or vehicle (n = 5) for 10 consecutive days. On Day 5, as compared to the vehicle-treated mice (230.5 +/- 13.5 mg/dl, mean +/- S.E), mice from both treated groups showed significantly lower fasting blood glucose levels (187.4 +/- 20.5 mg/dl and 187.4 +/- 17.1 mg/dl), respectively (both P < 0.05). On Day 10, compared to the vehicle group (240.1 +/- 12.3 mg/dl), the 50 mg/kg dose group were at 188.4 +/- 12.6 mg/dl (P < 0.05), and the 150 mg/kg dose group were normoglycemic (148.8 +/- 17.6 mg/dl, P < 0.01). Those ob/ob mice treated with vehicle did not, however, show significant changes in fasting blood glucose levels. Data from the intraperitoneal glucose tolerance test (IPGTT) showed that, compared to Day 0, there was a significant improvement in glucose tolerance in animals who received the 50 and 150 mg/kg polysaccharide doses, and the area under the curve (AUC) decreased 15.5% (P < 0.05) and 28.2% (P < 0.01), respectively. Interestingly, after cessation of polysaccharide treatment, the fasting blood glucose levels stayed lower, and returned to control concentration on Day 30. We also observed that the polysaccharides fraction did not affect body weight changes in ob/ob mice. Our data suggest that the polysaccharides fraction from American ginseng berry extract has a potential clinical utility in treating diabetic patients.

Anti-hyperglycemic effects of ginseng: comparison between root and berry

Previous studies demonstrated that both ginseng root and ginseng berry possess anti-diabetic activity. However, a direct comparison between the root and the berry under the same experimental conditions has not been conducted. In the present study, we compared anti-hyperglycemic effect between Panax ginseng root and Panax ginseng berry in ob/ob mice, which exhibit profound obesity and hyperglycemia that phenotypically resemble human type-2 diabetes. We observed that ob/ob mice had high baseline glucose levels (195 mg/dl). Ginseng root extract (150 mg/kg body wt.) and ginseng berry extract (150 mg/kg body wt.) significantly decreased fasting blood glucose to 143 +/- 9.3 mg/dl and 150 +/- 9.5 mg/dl on day 5, respectively (both P < 0.01 compared with the vehicle). On day 12, although fasting blood glucose level did not continue to decrease in the root group (155 +/- 12.7 mg/dl), the berry group became normoglycemic (129 +/- 7.3 mg/dl; P < 0.01). We further evaluated glucose tolerance using the intraperitoneal glucose tolerance test. On day 0, basal hyperglycemia was exacerbated by intraperitoneal glucose load, and failed to return to baseline after 120 min. After 12 days of treatment with ginseng root extract (150 mg/kg body wt.), the area under the curve (AUC) showed some decrease (9.6%). However, after 12 days of treatment with ginseng berry extract (150 mg/kg body wt.), overall glucose exposure improved significantly, and the AUC decreased 31.0% (P < 0.01). In addition, we observed that body weight did not change significantly after ginseng root extract (150 mg/kg body wt.) treatment, but the same concentration of ginseng berry extract significantly decreased body weight (P < 0.01). These data suggest that, compared to ginseng root, ginseng berry exhibits more potent anti-hyperglycemic activity, and only ginseng berry shows marked anti-obesity effects in ob/ob mice.

Ginseng berry reduces blood glucose and body weight in db/db mice

In this study, we observed anti-diabetic and anti-obesity effects of Panax ginseng berry in adult C57BL/Ks db/db mice and their lean littermates. Animals received daily intraperitoneal injections of Panax ginseng berry extract at 150 mg/kg body wt. for 12 consecutive days. On Day 5, the extract-treated db/db mice had significantly lower fasting blood glucose levels as compared to vehicle-treated mice (180.5+/-10.2 mg/dl vs. 226.0+/-15.3 mg/dl, P < 0.01). On day 12, the extract-treated db/db mice were normoglycemic (134.3+/-7.3 mg/dl) as compared to vehicle-treated mice (254.8+/-24.1 mg/dl; P < 0.01). Fasting blood glucose levels of lean mice did not decrease significantly after treatment with extract. After 12 days of treatment with the extract, glucose tolerance increased significantly, and overall blood glucose exposure calculated as area under the curve (AUC) decreased 53.4% (P < 0.01) in db/db mice. Furthermore, db/db mice treated with extract (150 mg/kg body wt.) showed weight loss from 51.0+/-1.9 g on Day 0, to 46.6+/-1.7 g on Day 5, and to 45.2+/-1.4 g on Day 12 (P < 0.05 and P < 0.01 compared to Day 0, respectively). The body weight of lean littermates also decreased at the same dose of extract. These data suggest that Panax ginseng berry extract may have therapeutic value in treating diabetic and obese patients.

Anti-HIV activity of medicinal herbs: usage and potential development

The acquired immunodeficiency syndrome (AIDS) is a result of human immunodeficiency virus (HIV) infection which subsequently leads to significant suppression of immune functions. AIDS is a significant threat to the health of mankind, and the search for effective therapies to treat AIDS is of paramount importance. Several chemical anti-HIV agents have been developed. However, besides the high cost, there are adverse effects and limitations associated with using chemotherapy for the treatment of HIV infection. Thus, herbal medicines have frequently been used as an alternative medical therapy by HIV positive individuals and AIDS patients. The aim of this review is to summarize research findings for herbal medicines, which are endowed with the ability to inhibit HIV. In this article, we will emphasize a Chinese herbal medicine, Scutellaria baicalensis Georgi and its identified components (i.e., baicalein and baicalin), which have been shown to inhibit infectivity and replication of HIV. Potential development of anti-AIDS compounds using molecular modeling methods will also be discussed.

Biphasic effect of cardiac glycosides on action potential duration in isolated Purkinje fibers

Despite the historical use of cardiac glycosides, the data describing the electrophysiological characteristics of this class of drug are not fully clear. The present study reported the biphasic effect of cardiac glycosides, digoxin (1.25 microM) and acetylstrophanthidin (0.15 microM), on action potential duration in isolated Purkinje fibers by the conventional glass microelectrode technique. At the cycle lengths of 990, 690 and 490 msec., action potential duration lengthened within 10 min. and shortened after 10 min. of digoxin and acetylstrophanthidin administration. The biphasic effect was observed at a concentration of 4.0 mM [K(+)]o. However, at a higher [K(+)]o concentration of 5.4 mM, only the shortening effect on action potential duration was recorded. These results suggest that the biphasic effect of cardiac glycosides on action potential duration is related to the concentration of extracellular potassium and is not related to the stimulating cycle lengths.

Herbal medicines and perioperative care

CONTEXT

Widespread use of herbal medications among the presurgical population may have a negative impact on perioperative patient care.

OBJECTIVES

To review the literature on commonly used herbal medications in the context of the perioperative period and provide rational strategies for managing their preoperative use.

DATA SOURCES

The MEDLINE and Cochrane Collaboration databases were searched for articles published between January 1966 and December 2000 using the search terms herbal medicine, phytotherapy, and alternative medicine and the names of the 16 most commonly used herbal medications. Additional data sources were obtained from manual searches of recent journal articles and textbooks.

STUDY SELECTION

We selected studies, case reports, and reviews addressing the safety and pharmacology of 8 commonly used herbal medications for which safety information pertinent to the perioperative period was available.

DATA EXTRACTION

We extracted safety, pharmacodynamic, and pharmacokinetic information from the selected literature and reached consensus about any discrepancies.

DATA SYNTHESIS

Echinacea, ephedra, garlic, ginkgo, ginseng, kava, St John's wort, and valerian are commonly used herbal medications that may pose a concern during the perioperative period. Complications can arise from these herbs' direct and pharmacodynamic or pharmacokinetic effects. Direct effects include bleeding from garlic, ginkgo, and ginseng; cardiovascular instability from ephedra; and hypoglycemia from ginseng. Pharmacodynamic herb-drug interactions include potentiation of the sedative effect of anesthetics by kava and valerian. Pharmacokinetic herb-drug interactions include increased metabolism of many drugs used in the perioperative period by St John's wort.

CONCLUSIONS

During the preoperative evaluation, physicians should explicitly elicit and document a history of herbal medication use. Physicians should be familiar with the potential perioperative effects of the commonly used herbal medications to prevent, recognize, and treat potentially serious problems associated with their use and discontinuation.

Effects of qian-kun-nin, a Chinese herbal medicine formulation, on HIV positive subjects: a pilot study

Qian-kun-nin is a Chinese herbal formulation considered to have anti-infection, anti-tumor and immuno-enhancing properties. Data from previous investigations showed that qian-kun-nin causes HIV growth inhibition and immunomodulation in vitro, suggesting that this formula has the ability to inhibit HIV and modulate impaired immune functions in humans. We conducted this pilot study to evaluate the anti-retroviral and immunological enhancing effects of this formula on HIV positive subjects. Eight subjects completed the study, receiving oral qian-kun-nin capsules for 24 consecutive weeks in a single blind design. Compared to baseline level, the plasma virus load decreased significantly at the end of week 12 (p < 0.01) and week 24 (p < 0.01), respectively. Four weeks after cessation of qian-kun-nin treatment, plasma virus load was still significantly lower compared to baseline (p < 0.01). Blood CD4 cell counts were increased significantly at the end of the 12th week compared to the baseline level (p < 0.01). No adverse effects were observed, and no significant side effects were recorded in any subjects. These data suggest that qian-kun-nin has therapeutic potential in the treatment of HIV positive patients.

Effects of Panax quinquefolius L. on brainstem neuronal activities: comparison between Wisconsin-cultivated and Illinois-cultivated roots

Brainstem neurons receiving subdiaphragmatic vagal inputs were recorded in an in vitro neonatal rat brainstem-gastric preparation. Aqueous extracts of American ginseng root (Panax quinquefolius L.) from Wisconsin and Illinois were applied to the gastric compartment or the brainstem compartment of the bath chamber to evaluate the peripheral gut or central brain effects of the extracts on brainstem unitary activity. After P. quinquefolius extract application to the gastric or brainstem compartment, a concentration-related inhibition in neuronal discharge frequency in brainstem unitary activity was observed, suggesting that P. quinquefolius plays an important role in regulating the digestive process and modulating the brain function in the rat. In this study, pharmacological effects of Wisconsin-cultivated P. quinquefolius and Illinois-cultivated P. quinquefolius were compared. Our results showed that Illinois-cultivated P. quinquefolius possesses a significantly stronger peripheral gastric as well as central brain modulating effect on brainstem neuronal activity. Data from our high performance liquid chromatography ginsenoside analysis suggest that this increase in inhibitory effects by Illinois-cultivated P. quinquefolius may be due to its different ginsenoside profile.

Cardiac toxicity of resibufogenin: electrophysiological evidence

Resibufogenin (RBG) is a single compound isolated from Chansu, a traditional Chinese medicine obtained from the skin venom gland of the toad. Formulations of Chansu have been widely applied in China, Japan, and other Asian countries for a long time and are currently used as alternative medicines. However, there have been several reports about the toxicity of Chansu and its medical formulations in the United States recently. As digitalis, RBG possesses both pharmacologic and toxicologic effects. According to our study results, RBG, one of major ingredient of Chansu, induced delayed afterdepolarization and triggered arrhythmias both in cardiac fiber in vitro and in beating heart in vivo at the high concentrations. The electrophysiologic toxic effects of RBG, the possible mechanism of toxicity, and treatment possibilities are discussed in the present review

Effects of resibufogenin from toad venom on isolated Purkinje fibers

Chan su (dried toad venom) is a traditional Chinese medicine obtained from the skin venom gland of the toad. Chan su has long been used as a therapeutic agent in China and other Asian countries. Recent reports indicate that Chan su toxicity carries a high mortality rate in the United States. This study focused upon the cardiac electrophysiological and electro-toxicity effects of resibufogenin (RBG), one of the major components in Chan su. Action potentials of isolated sheep and canine heart Purkinje fibers were studied using glass microelectrode recording techniques. The results indicate that RBG significantly affected all parameters of transmembrane action potential, induced delayed after depolarization, and triggered arrhythmias in sheep and canine Purkinje fibers.

Voltage-dependent inhibition of brain Na(+) channels by American ginseng

American ginseng (Panax quinquefolius) is a major species of ginseng that has many pharmacological effects. Studies have demonstrated that constituents of ginseng have neuroprotective effects during ischemia. Neuronal damage during ischemic episodes has been associated with abnormal Na(+) fluxes. Drugs that block voltage-dependent Na(+) channels provide cytoprotection during cerebral ischemia. We thus hypothesized that American ginseng may block Na(+) channels. In this study, effects of an American ginseng aqueous extract was evaluated in tsA201 cells transfected with cDNA expressing alpha subunits of the Brain(2a) Na(+) channel using the whole-cell patch clamp technique. We found that American ginseng extract tonically and reversibly blocked the channel in a concentration- and voltage-dependent manner. It shifted the voltage-dependence of inactivation by 14 mV (3 mg/ml) in the hyperpolarizing direction and delayed recovery from inactivation, whereas activation of the channel was unaffected. Ginsenoside Rb(1), a major constituent of the American ginseng extract, produced similar effects. The data were compared with the actions of lidocaine, a Na(+) channel blocker. Our results suggest that Na(+) channel block by American ginseng extract and Rb(1) was primarily due to interaction with the inactive state of the channel. Inhibition of the Na(+) channel activity by American ginseng extract may contribute to its neuroprotective effect during ischemia.

S-Adenosyl-L-homocysteine hydrolase inhibitor mediates immunosuppressive effects in vivo: suppression of delayed type hypersensitivity ear swelling and peptidoglycan polysaccharide-induced arthritis

A specific and potent inhibitor of S-adenosyl-L-homocysteine (AdoHcy) hydrolase, 9-[(1'R,2'S,3'R)-2', 3'-dihydroxycyclopentanyl]adenine (DHCaA), was evaluated for its immunosuppressive efficacy on murine T-cell proliferation in vitro and in several animal models, including delayed type hypersensitivity ear swelling and peptidoglycan polysaccharide-induced arthritis. The concanavalin A-induced [(3)H]thymidine incorporation into T cells was strongly inhibited by DHCaA with a 50% inhibition concentration (IC(50)) of 0.3 microM. In vivo, a dose-dependent reduction (39, 62, and 73%) of ear swelling was observed when 2,4-dinitrofluorobenzene-treated mice were orally administered with DHCaA at 1, 5, and 10 mg/kg, respectively. This inhibition in ear swelling dose dependently corresponded to the inhibition of AdoHcy hydrolase activity in the spleen. The more potent the AdoHcy hydrolase inhibitor, the stronger the immunosuppressive efficacy observed. In rat peptidoglycan polysaccharide-induced arthritis, orally dosed DHCaA significantly suppressed inflamed paw volumes with minimal effective dose of 0.1 mg/kg. At a dose of 1 mg/kg, DHCaA almost completely inhibited paw swelling. This inhibition of paw swelling was associated with an inhibition of interleukin-1beta production in joint tissues. Histopathological evaluation of the joints in rats treated with 1 mg/kg showed a significant improvement in the reduction of the histopathological grading score from untreated scores of 10.44 to 4. 78. Results from this study indicate that inhibitors of AdoHcy hydrolase could be effective anti-inflammatory agents.

Extracellular detection of delayed afterdepolarization of cardiac fibers using signal averaging technique

AIM

To detect delayed after depolarizations (DAD) in extracellular electrograms using signal averaging technique.

METHODS

DAD were induced by acetylstrophanthidin (0.25 mumol.L-1, n = 9) and resibufogenin (0.52 mumol.L-1, n = 5) in sheep cardiac Purkinje fibers. Intracellular voltage was recorded with a conventional microelectrode, and simultaneous extracellular electrograms were recorded differentially from widely spaced electrodes placed in the tissue bath. Noise of electrograms was reduced using signal averaging technique.

RESULTS

Acetylstrophanthidin and resibufogenin both induced DAD in the intracellular recording and extracellular DAD (DAD-E) in the extracellular electrogram in sheep heart Purkinje fibers. Acetylstrophanthidin and resibufogenin induced typical changes in the action potential including decrease in action potential amplitude, resting potential, maximum diastolic potential, and action potential duration. Similar shortening occurred in the "Q-T interval" recorded by the extracellular electrogram. With either acetylstrophanthidin or resibufogenin, shortening of stimulation cycle length from 990 ms to 690 ms reduced the coupling interval between action potential upstroke and peak voltage of the DAD (P < 0.01), and the coupling interval between the "QRS" and DAD-E recorded extracellularly (P < 0.01).

CONCLUSION

DAD can be detected using the extracellular electrograms combined with the high resolution, signal averaging technique.

Gastric effects of cholecystokinin and its interaction with leptin on brainstem neuronal activity in neonatal rats

Cholecystokinin (CCK) is a major gastrointestinal neuropeptide that is secreted in response to food ingestion. It is involved in the feedback regulation of gastric emptying and also modulates food intake. Leptin, a hormone that regulates food intake and energy balance, is secreted from adipose tissue, gastric mucosa, fundic glands, and other tissues. In a previous report we showed that gastric effects of leptin activated the nucleus tractus solitarius (NTS) neurons responding to gastric vagal stimulation. In this study, using the same in vitro neonatal rat preparation, we investigated the gastric effects of CCK and its interaction with leptin on NTS neurons receiving gastric vagal inputs. We observed that peripheral gastric effects of CCK (300 nM) produced a mean activation response of 271 +/- 3.9% compared with control level (100%) in 33 (60%) neurons tested (P <.01), and this response was abolished by a CCK-A receptor antagonist. A concentration-dependent effect of CCK (10 nM-1.0 microM) on NTS neuronal discharge frequencies was shown. We also observed that leptin (10 nM) applied to the stomach produced a mean activation response of 183 +/- 5.3% in 13 (50%) NTS units that responded to CCK (P <.01). Furthermore, we evaluated the combined effect of CCK and leptin in two groups of NTS neurons. Those NTS units that showed activation responses to both CCK (300 nM) and leptin (10 nM) had a subadditive effect that produced a mean activation response of 338 +/- 12.9% compared with the control level in all 10 (100%) neurons tested (P <.01). Eight (36%) of another 22 units that were not affected by either CCK (300 nM) or leptin (10 nM) alone had an activation response (151 +/- 5.2%; P <.05) when the same concentrations of CCK and leptin were applied together. Subsequently, by comparing the effects of CCK and leptin on a whole-stomach preparation to a partial-stomach preparation, we examined the area of the stomach in which gastric receptors contributed most to NTS unitary activity. We showed that the distal stomach containing the pylorus determined CCK gastric activity, whereas both the proximal and distal stomach are important for leptin's effect. Our data suggest that leptin modulates the potency of CCK signals that modify food intake in the neonatal rat.

Leptin reduces body weight gain in neonatal rats

Leptin (OB protein) elicits a neuroendocrine response to starvation and states of nutritional abundance to stabilize the proportion of body fat. Leptin has dramatic effects on food intake and energy expenditure in adult and juvenile rodents. However, whether the neonatal period is associated with the development of an effective leptin feedback system is still not known. In this study, we evaluated the effects of peripherally administered leptin on body weight changes in neonatal rats during the early suckling period (from birth to 10 d). Our results show that daily i.p. injections of leptin (0.3 microg/g and 1.0 microg/g) to neonatal rats led to a significant reduction in weight gain over 10 d compared with the control group (p < 0.01 and p < 0.01, respectively). Concomitant with a reduction in weight gain, retroperitoneal fat pad weight also significantly decreased in the leptin-treated group. Our data indicate that the potential for energy balance regulation by leptin occurs in the first day after birth. In addition, we also observed that 3 d after discontinuing leptin treatment, the body weight as well as the fat pad weight of leptin-treated pups returned to the control level. Our results demonstrate that leptin reduces body weight gain in neonatal rats.

Treatment of insomnia: an alternative approach

Insomnia is the most common sleep disorder, and is often associated with significant medical, psychological, and social disturbances. Conventional medical treatment for insomnia includes psychological and pharmacological approaches; however, long-term use of frequently prescribed medications can lead to habituation and problematic withdrawal symptoms. Therefore, herbal and other natural sleep aids are gaining popularity, as herbs commonly used for their sedative-hypnotic effects do not have the drawbacks of conventional drugs. Whether alternative therapies possess activity similar to conventional therapies needs further evaluation.

Effects of enteric-coated methylnaltrexone in preventing opioid-induced delay in oral-cecal transit time

BACKGROUND

Methylnaltrexone is the first peripheral opioid receptor antagonist. It has the potential to prevent or reverse the peripherally mediated gastrointestinal effects of opioids. In previous human volunteer trials, we demonstrated that oral uncoated methylnaltrexone prevented morphine-induced delay in gastrointestinal transit time.

METHODS

This trial consisted of two studies: a pilot study and a controlled study. The lactulose hydrogen breath test was used to measure the oral-cecal transit time.

RESULTS

In the pilot study with three subjects, an oral dose of 6.4 mg/kg enteric-coated methylnaltrexone effectively reversed the effects of morphine, producing transit times shorter than baseline levels. Subsequently, in the controlled study with another nine subjects, the transit time increased after intravenous morphine administration in all nine subjects, and the lower dose (3.2 mg/kg) of enteric-coated methylnaltrexone completely prevented the morphine-induced change in oral-cecal transit time in all nine subjects. Morphine significantly increased oral-cecal transit time from baseline level of 96.7 +/- 54.1 minutes (mean +/- SD) to 155.0 +/- 53.6 minutes (P = .014). After enteric-coated methylnaltrexone and morphine, the transit time returned to the baseline level (93.3 +/- 56.0 minutes; P = .55 compared with placebo). Plasma concentrations after 6.4 mg/kg and 3.2 mg/kg enteric-coated methylnaltrexone were substantially lower compared with those after 6.4 mg/kg of the uncoated formulation.

CONCLUSION

Our results suggest that there is a prevailing direct and local luminal effect of enteric-coated methylnaltrexone and that the enteric-coated formulation exerts its gut pharmacologic actions more efficiently than the uncoated formulation.

Enhancement of delayed afterdepolarizations and triggered activity by class III antiarrhythmic drugs: multiple effects of E-4031 and dofetilide

The effects of class III antiarrhythmic agents E-4031 and dofetilide were studied on action potentials and subthreshold delayed afterdepolarizations (DADs) induced by the cardiac glycoside acetylstrophanthidin (AS) in isolated cardiac Purkinje fibers. Action potentials were recorded from cardiac Purkinje fibers using microelectrode techniques. E-4031 and dofetilide consistently increased DAD amplitude, occasionally caused triggered action potentials and shortened action potential duration. The application of E-4031 without prior AS exposure, resulted in the typical class III antiarrhythmic effects of action potential lengthening and the induction of early afterdepolarizations. These findings suggest that under our conditions of AS-induced cell Ca2+ overload, the effects of the "pure" class III antiarrhythmic drugs, E-4031 and dofetilide, are markedly different from those found in non-Ca2+ loaded cells. This may represent an additional electrophysiological mechanism for class III antiarrhythmic drug toxicity.

Methylnaltrexone for reversal of constipation due to chronic methadone use: a randomized controlled trial

CONTEXT

Constipation is the most common chronic adverse effect of opioid pain medications in patients who require long-term opioid administration, such as patients with advanced cancer, but conventional measures for ameliorating constipation often are insufficient.

OBJECTIVE

To evaluate the efficacy of methylnaltrexone, the first peripheral opioid receptor antagonist, in treating chronic methadone-induced constipation.

DESIGN

Double-blind, randomized, placebo-controlled trial conducted between May 1997 and December 1998.

SETTING

Clinical research center of a university hospital.

PARTICIPANTS

Twenty-two subjects (9 men and 13 women; mean [SD] age, 43.2 [5.5] years) enrolled in a methadone maintenance program and having methadone-induced constipation.

MAIN OUTCOME MEASURES

Laxation response, oral-cecal transit time, and central opioid withdrawal symptoms were compared between the 2 groups.

RESULTS

The 11 subjects in the placebo group showed no laxation response, and all 11 subjects in the intervention group had laxation response after intravenous methylnaltrexone administration (P<.001). The oral-cecal transit times at baseline for subjects in the methylnaltrexone and placebo groups averaged 132.3 and 126.8 minutes, respectively. The average (SD) change in the methylnaltrexone-treated group was -77.7 (37.2) minutes, significantly greater than the average change in the placebo group (-1.4 [12.0] minutes; P<.001). No opioid withdrawal was observed in any subject, and no significant adverse effects were reported by the subjects during the study.

CONCLUSIONS

Our data demonstrate that intravenous methylnaltrexone can induce laxation and reverse slowing of oral cecal-transit time in subjects taking high opioid dosages. Low-dosage methylnaltrexone may have clinical utility in managing opioid-induced constipation.

Panax quinquefolium L. inhibits thrombin-induced endothelin release in vitro

Endothelial cell damage is considered to be the initial step in the genesis of thrombosis and arteriosclerosis, the common precursors of cardiovascular disorders. In this study, we evaluated the protective effects of American ginseng or Panax quinquefolium L. extracts on endothelial cell injury, and investigated effects of ginseng extracts on thrombin-induced endothelin release using cultured human umbilical vein endothelial cells. We observed that when endothelial cells pretreated with 1, 10, and 100 micrograms/ml of Panax quinquefolium L. extracts were incubated for 4 and 24 hr with thrombin, the concentration of endothelin was significantly decreased in a concentration dependent, time related manner (at 4 hr, IC50 = 5.1 micrograms/ml; at 24 hr, IC50 = 6.2 micrograms/ml). We further evaluated the effects of NG-nitro-L-arginine (NLA), a nitric oxide (NO) synthetase inhibitor, on the activity of Panax quinquefolium L. extracts. Following pretreatment of cultured endothelial cells with NLA, the inhibition of thrombin-induced endothelin release by Panax quinquefolium L. was significantly reduced (P < 0.05). This result suggests that the pharmacological action of Panax quinquefolium L. is, at least partially, due to NO release. Our data demonstrate that American ginseng may play a therapeutic role in facilitating the hemodynamic balance of vascular endothelial cells.

Ginseng pharmacology: multiple constituents and multiple actions

Ginseng is a highly valued herb in the Far East and has gained popularity in the West during the last decade. There is extensive literature on the beneficial effects of ginseng and its constituents. The major active components of ginseng are ginsenosides, a diverse group of steroidal saponins, which demonstrate the ability to target a myriad of tissues, producing an array of pharmacological responses. However, many mechanisms of ginsenoside activity still remain unknown. Since ginsenosides and other constituents of ginseng produce effects that are different from one another, and a single ginsenoside initiates multiple actions in the same tissue, the overall pharmacology of ginseng is complex. The ability of ginsenosides to independently target multireceptor systems at the plasma membrane, as well as to activate intracellular steroid receptors, may explain some pharmacological effects. This commentary aims to review selected effects of ginseng and ginsenosides and describe their possible modes of action. Structural variability of ginsenosides, structural and functional relationship to steroids, and potential targets of action are discussed.

Effects of quercetin on the release of endothelin, prostacyclin and tissue plasminogen activator from human endothelial cells in culture

Quercetin and related flavonoids are naturally occurring polyphenolic compounds with multiple pharmacological activities. Using cultured human umbilical vein endothelial cells, we investigated the effects of quercetin on endothelin (ET-1) and tissue plasminogen activator (t-PA) release induced by thrombin. We observed that when endothelial cells pretreated with 5 or 50 microM of quercetin were incubated for 4 and 24 h with thrombin, ET-1 concentration-dependently decreased (n = 6, P < 0.01, at 4 h IC50 = 1.54 microM, at 24 h IC50 = 2.78 microM). Under the same experimental conditions, quercetin significantly increased t-PA (n = 6, P < 0.01, at 4 h EC50 = 0.71 microM and at 24 hrs EC50 = 0.74 microM). In the same preparation, we evaluated prostacyclin (PGI2) release, induced by thrombin activated platelets, as determined by a 6-Keto-PGF1alpha radioimmunoassay. Following the treatment of cultured endothelial cells with activated platelets, the concentration of 6-Keto-PGF1alpha was significantly increased (P < 0.01). Quercetin (1, 5, and 20 microM) inhibited PGI2, in a concentration-dependent manner (n = 6, P < 0.05). Our data indicate that quercetin modulates the release of ET-1, t-PA, and PGI2 from vascular endothelial cells.

Extract from Scutellaria baicalensis Georgi attenuates oxidant stress in cardiomyocytes

Extract from Scutellaria baicalensis Georgi Attenuates Oxidant Stress in Cardiomyocytes. Journal of Molecular and Cellular Cardiology (1999) 31, 1885-1895. Scutellaria baicalensis Georgi is a Chinese herbal medicine used to treat allergic and inflammatory diseases. The medicinal effects of S. baicalensis root may result, in part, from its constituent flavones reported to have antioxidant properties. Since oxidants play multiple roles in cells, we tested whether S. baicalensis could confer protection in a cardiomyocyte model of ischemia and reperfusion. The intracellular fluorescent probes 2',7'-dichlorofluorescin diacetate (DCFH-DA, sensitive to H(2)O(2) and hydroxyl radicals) and dihydroethidium (DHE, sensitive to superoxide) were used to assess intracellular reactive oxygen species (ROS), and propidium iodide (PI) was used to assess viability in cultured embryonic cardiomyocytes. S. baicalensis extract (SbE) quickly attenuated levels of oxidants generated during transient hypoxia and during exposure to the mitochondrial site III inhibitor antimycin A, as measured by DCFH oxidation or by DHE oxidation. These attenuated oxidant levels were associated with improved survival and function. Cell death after ischemia/reperfusion decreased from 47+/-3 % in untreated to 26+/-2 % in S. baicalensis treated cells (P<0.001). After antimycin A exposure, S. baicalensis decreased cell death from 49+/-6 % in untreated to 23+/-4 % in treated cells. Return of contraction occurred in S. baicalensis-treated cells but was not observed in control cells. Other in vitro studies revealed that baicalein, a major flavone component of SbE can directly scavenge superoxide, hydrogen peroxide, and hydroxyl radicals. Collectively, these findings indicate that SbE and its constituent flavones such as baicalein can attenuate oxidant stress and protect cells from lethal oxidant damage in an ischemia-reperfusion model.

Peripheral gastric leptin modulates brain stem neuronal activity in neonates

Afferent sensory fibers are the primary neuroanatomic link between nutrient-related events in the gastrointestinal tract and the central neural substrates that modulate ingestion. In this study, we evaluated the peripheral gastric effects of leptin (OB protein) on brain stem neuronal activities using an in vitro neonatal rat preparation. We also tested gastric leptin effects as a function of age in neonates. For approximately 33% of the nucleus tractus solitarius units observed, gastric leptin (10 nM) produced a significant activation of 188.2 +/- 8.6% (mean +/- SE) compared with the control level of 100% (P < 0.01). Concentration-dependent leptin effects have also been shown. The remaining neurons (67%) had no significant response to gastric leptin application. Next, we evaluated the peripheral gastric effects of leptin (10 nM) on brain stem unitary activity in three different age groups (1-2 days old, 3-5 days old, and 7-8 days old) of neonatal rats. In the 1- to 2-day-old and the 3- to 5-day-old groups, we observed that response ratios and activity levels were similar. However, there was a significant difference between the 7- to 8-day-old group and the two younger age groups in both the response ratios and the activation levels. The percentage of activation responses increased from approximately 26% in the 1- to 2-day-old and the 4- to 5-day-old age groups to 70% in the 7- to 8-day-old group (P < 0.05). The level of activation increased from 168.3 +/- 2.7% (compared with the control level) in the 1- to 2-day-old and the 4- to 5-day-old age groups to 231.4 +/- 11.9% in the 7- to 8-day-old group (P < 0.01). Our data demonstrate that peripheral gastric leptin modulates brain stem neuronal activity and suggest that gastric leptin has a significantly stronger effect in the 7- to 8-day-old animals than in the younger neonates.

Gastric effects of methylnaltrexone on mu, kappa, and delta opioid agonists induced brainstem unitary responses

In this study, we evaluated the gastric effects of methylnaltrexone, an opioid receptor antagonist that does not cross the blood-brain barrier in vivo, on mu, kappa and delta opioid agonists induced brainstem unitary responses in an in vitro neonatal rat brainstem-gastric preparation. Single units in the medial subnucleus of the nucleus tractus solitarius (NTS), responding to electrical stimulation of subdiaphragmatic vagal fibers, were recorded. Selective opioid receptor agonists and antagonists were applied only to the gastric compartment of the bath chamber and thus, the brainstem functions of the preparation were not affected by the drugs. The peripheral gastric effects of a mu opioid receptor agonist, DAMGO, and a kappa opioid receptor agonist, U-50,488H, were evaluated on 58 tonic units that received the subdiaphragmatic vagal inputs. For approximately 78% of the units observed, DAMGO (1.0 microM) and U-50,488H (1.0 microM) induced a concentration-dependent inhibition of 62.1+/-9.3% (mean +/- SE) and 49.2+/-6.5% of the control level of the NTS neuronal activity, respectively. Methylnaltrexone competitively antagonized the DAMGO-induced brainstem neuronal effects. Methylnaltrexone at an 18.8-fold higher concentration also reversed U-50,488H-induced NTS neuronal responses. Naloxone, a non-selective opioid receptor antagonist, reversed the inhibitory effects of DAMGO and U-50,488H at much lower concentrations (3.8% and 0.5%, respectively) compared to methylnaltrexone. Only 18% of the NTS neurons evaluated showed inhibitory responses to a delta receptor agonist, DPDPE, (19.7+/-5.0% at 10 microM), and this inhibition could not be reversed by methylnaltrexone in the concentration range we tested. In addition, when methylnaltrexone (1.0 microM) alone was applied to the gastric compartment, there was an activation (8.5+/-2.1%) of the NTS neurons receiving subdiaphragmatic vagal inputs, suggesting an endogenous gastric opioid action in the modulation of brainstem neuronal activities.

Effects of low-dose morphine on gastric emptying in healthy volunteers

Appropriate preoperative pain therapy for patients undergoing surgery may be withheld due to the fear that opioids will inhibit gastric emptying and increase the risk of aspiration. Previously, doses of 5 to 10 mg of morphine have been shown to delay gastric emptying time. However, the effect of lower doses of morphine on gastric emptying in humans has not been reported. In this study, the effects of intravenous morphine 0.05 mg/kg-3.5 mg for 70-kg body weight, a dose that can cause analgesia--on gastric emptying were evaluated in a double-blind, randomized, placebo-controlled study in 15 healthy human volunteers using the acetaminophen test. Our data indicated that this low dose of morphine significantly prolonged the gastric emptying time. Thus, even small doses of morphine inhibit gastric emptying. This effect may be important in patients undergoing surgery, in patients receiving other oral medications after surgery in ambulatory settings, and in instances of patient-controlled analgesia.

Gut motility and transit changes in patients receiving long-term methadone maintenance

This study was conducted to survey gut motility and transit in 19 volunteers receiving methadone maintenance who were opioid-dependent, and to measure the oral-cecal transit time in these individuals using the lactulose hydrogen breath test. None of these patients reported constipation problems before use of illicit drugs. During current long-term methadone therapy, 58% of patients experienced some degree of constipation, and two of these 19 patients reported that constipation was a very serious problem. Mean +/- standard deviation (SD) oral-cecal transit time in these individuals was 159+/-49.2 minutes, which is significantly longer than the transit time recorded in two previous studies of healthy volunteers (P < 0.01). These results indicate that tolerance to opioids does not appear to extend to gastrointestinal motility and transit. It seems that patients receiving long-term methadone therapy are a good model for use in evaluating gastrointestinal effects of opioid antagonists.

Efficacy of orally administered methylnaltrexone in decreasing subjective effects after intravenous morphine

Opioid compounds are commonly used analgesics. After opioid administration, troublesome subjective effects, such as dysphoria, dizziness, nausea, and pruritus, have been reported. While some if not all of these are believed to occur due to central nervous system effects of opioids, the anecdotal reports heard from volunteers in our other studies suggest that a peripheral opioid antagonist reduced some of these effects. In this double-blind randomized placebo-controlled study, we evaluated the efficacy of oral methylnaltrexone, a selective peripheral opioid receptor antagonist, to decrease subjective effects after administering morphine to normal human volunteers. After intravenous morphine injection (0.05 mg/kg), significant increases in subjective ratings were obtained on 'nauseous', 'skin itch', 'stimulated', and 'flushing'. Oral methylnaltrexone 19.2 mg/kg significantly decreased these four ratings. Plasma methylnaltrexone concentrations at two different oral doses were also measured to correlate between pharmacological effects of the compound and its plasma levels. Our results suggested that methylnaltrexone has a potential therapeutic value in decreasing some undesirable subjective effects associated with opioid medications.

Modulation of American ginseng on brainstem GABAergic effects in rats

Single neurons in the region of the medial nucleus tractus solitarius (NTS), responding or not responding to gastric vagal branch stimulation, were recorded in an in vitro neonatal rat brainstem-gastric preparation. The spontaneous activity of the majority of these two types of NTS units was inhibited by GABA(A) receptor agonist, muscimol (30 microM), and this inhibition (approximately 52% compared to 100% of the control level) could be antagonized by selective GABA(A) receptor antagonist, bicuculline (10 microM). Application of Panax quinquefolium L. extracts (3.0 microg/ml) into the brainstem compartment of the preparation also significantly reduced the discharge rate of these NTS neurons (approximately 27% compared to the control level), but this reduction could not be reversed by bicuculline (10 microM). Pretreatment with Panax quinquefolium L. (3.0 microg/ml) significantly decreased the NTS inhibitory effects induced by muscimol (30 microM), approximately from 51 to 33%. Our results demonstrated the interactions of Panax quinquefolium L. with ligand-bindings of GABA(A) receptors, and the modulation of the brainstem GABAergic mechanism by Panax quinquefolium L. Our data suggest that the regulation of GABAergic neurotransmission may be an important action of Panax quinquefolium L.

Inactivation of S-adenosyl-L-homocysteine hydrolase and antiviral activity with 5',5',6',6'-tetradehydro-6'-deoxy-6'-halohomoadenosine analogues (4'-haloacetylene analogues derived from adenosine)

Treatment of a protected 9-(5, 6-dideoxy-beta-D-ribo-hex-5-ynofuranosyl)adenine derivative with silver nitrate and N-iodosuccinimide (NIS) and deprotection gave the 6'-iodo acetylenic nucleoside analogue 3c. Halogenation of 3-O-benzoyl-5,6-dideoxy-1, 2-O-isopropylidene-alpha-D-ribo-hex-5-enofuranose gave 6-halo acetylenic sugars that were converted to anomeric 1,2-di-O-acetyl derivatives and coupled with 6-N-benzoyladenine. These intermediates were deprotected to give the 6'-chloro 3a, 6'-bromo 3b, and 6'-iodo 3c acetylenic nucleoside analogues. Iodo compound 3c appears to inactivate S-adenosyl-L-homocysteine hydrolase by a type I ("cofactor depletion") mechanism since complete reduction of enzyme-bound NAD+ to NADH was observed and no release of adenine or iodide ion was detected. In contrast, incubation of the enzyme with the chloro 3a or bromo 3b analogues resulted in release of Cl- or Br- and Ade, as well as partial reduction of E-NAD+ to E-NADH. Compounds 3a, 3b, and 3c were inhibitory to replication of vaccinia virus, vesicular stomatitis virus, parainfluenza-3 virus, and reovirus-1 (3a < 3b < 3c, in order of increasing activity). The antiviral effects appear to correlate with type I mechanism-based inhibition of S-adenosyl-L-homocysteine hydrolase. Mechanistic considerations are discussed.

Prevention of apomorphine- or cisplatin-induced emesis in the dog by a combination of methylnaltrexone and morphine

PURPOSE

Morphine can have either an emetic or an antiemetic effect. The emetic effect of morphine can be blocked by methylnaltrexone (MNTX), a quaternary opioid antagonist with peripheral action. In this study, we tested the hypothesis that administering MNTX to block the peripheral emetic effect of morphine would unmask the central antiemetic effect of the morphine. The net result, we hypothesized, would be a reduction in apomorphine- or cisplatin-induced emesis.

METHODS

MNTX 0.25 mg/kg and morphine 1 mg/kg were administered to conscious dogs which were then challenged with the potent emetic agents apomorphine or cisplatin. Emesis was assessed by the presence of characteristic retching motions accompanied by the regurgitation of gastric contents.

RESULTS

We observed that apomorphine challenges of 0.1 mg/kg and of 0.03 mg/kg produced 100% emesis in control animals. After pretreatment with MNTX and morphine, the frequency of emesis with the larger dose of apomorphine was reduced to 50% and with the smaller dose to 22%. MNTX alone did not block apomorphine-induced emesis. In animals challenged with cisplatin 3 mg/kg, the emetic response was 100%. Emesis did not occur in animals pretreated with MNTX 0.25 mg/kg and morphine 1 mg/kg before cisplatin.

CONCLUSIONS

Our results demonstrate that MNTX combined with morphine reduces apomorphine-induced emesis and blocks cisplatin-induced emesis. These results support the hypothesis that the emetic effect of morphine is peripheral and its antiemetic action is central. In combination, MNTX and morphine may have a clinical role in the treatment of chemotherapy-induced emesis.

GABAergic effects on nucleus tractus solitarius neurons receiving gastric vagal inputs

Single units in the region of the medial nucleus tractus solitarius (NTS), responding to electrical stimulation of gastric vagal fibers, were recorded in an in vitro neonatal rat brainstem-gastric preparation. gamma-Aminobutyric acid (GABA) subreceptor agonists and antagonists were applied to the gastric and brainstem compartments of the bath chamber to evaluate the peripheral gastric and central brainstem GABAergic effects on NTS neuronal activity. The gastric effects of the GABAA receptor agonist muscimol and GABAB receptor agonist baclofen were evaluated on 55 tonic units that received the gastric vagal inputs. For approximately 58% (32 of 55) and 38% (21 of 55) of the units observed, muscimol (30 microM; IC50 = 2.0 microM) and baclofen (30 microM; IC50 = 1.5 microM) in the gastric compartment induced a concentration-dependent inhibition of 36.2 +/- 3.1% (mean +/- S.E.) and 31.0 +/- 2.9% of the control level of the NTS neuronal activity, respectively. The brainstem effects of muscimol and baclofen were tested on 51 units. For approximately 90% (46 of 51) and 78% (40 of 51) of the units tested, muscimol (30 microM; IC50 = 1.3 microM) and baclofen (30 microM; IC50 = 1.1 microM) in the brainstem compartment produced a concentration-dependent inhibition of 54.1 +/- 3.4% and 48.9 +/- 3. 5% of the control level, respectively. The remaining NTS units were not affected by these two GABA agonists. Bicuculline (10 microM) and saclofen (10 microM), the GABAA and GABAB subreceptor antagonists, competitively antagonized the gastric and brainstem effects by muscimol and baclofen, respectively. Our results demonstrated that both GABAA and GABAB receptors in the stomach and brainstem play an important role in activity modulation of the medial NTS neurons receiving gastric vagal inputs in neonatal rats.

Discovery of type II (covalent) inactivation of S-adenosyl-L-homocysteine hydrolase involving its "hydrolytic activity": synthesis and evaluation of dihalohomovinyl nucleoside analogues derived from adenosine

Treatment of the 5'-carboxaldehyde derived by Moffatt oxidation of 6-N-benzoyl-2',3'-O-isopropylideneadenosine (1) with the "(bromofluoromethylene)triphenylphosphorane" reagent and deprotection gave 9-(6-bromo-5, 6-dideoxy-6-fluoro-beta-d-ribo-hex-5-enofuranosyl)adenine (4). Parallel treatment with a "dibromomethylene Wittig reagent" and deprotection gave 9-(6,6-dibromo-5, 6-dideoxy-beta-d-ribo-hex-5-enofuranosyl)adenine (7), which also was prepared by successive bromination and dehydrobromination of the 6'-bromohomovinyl nucleoside 8. Bromination-dehydrobromination of the 5'-bromohomovinyl analogue 11 and deprotection gave (E)-9-(5, 6-dibromo-5,6-dideoxy-beta-d-ribo-hex-5-enofuranosyl)adenine (15). Compounds 4, 7, and 15 were designed as putative substrates of the "hydrolytic activity" of S-adenosyl-l-homocysteine (AdoHcy) hydrolase. Enzyme-mediated addition of water across the 5,6-double bond could generate electrophilic acyl halide or alpha-halo ketone species that could undergo nucleophilic attack by proximal groups on the enzyme. Such type II (covalent) mechanism-based inactivation is supported by protein labeling with 8-[3H]-4 and concomitant release of bromide and fluoride ions. Incubation of AdoHcy hydrolase with 7 or 15 resulted in irreversible inactivation and release of bromide ion. In contrast with type I mechanism-based inactivation, reduction of enzyme-bound NAD+ to NADH was not observed. Compounds 4, 7, and 15 were not inhibitory to a variety of viruses in cell culture, and weak cytotoxicity was observed only for CEM cells.

A novel mechanism-based inhibitor (6'-bromo-5', 6'-didehydro-6'-deoxy-6'-fluorohomoadenosine) that covalently modifies human placental S-adenosylhomocysteine hydrolase

Most inhibitors of S-adenosylhomocysteine (AdoHcy) hydrolase function as substrates for the "3'-oxidative activity" of the enzyme and convert the enzyme from its active form (NAD+) to its inactive form (NADH) (Liu, S., Wolfe, M. S., and Borchardt, R. T. (1992) Antivir. Res. 19, 247-265). In this study, we describe the effects of a mechanism-based inhibitor, 6'-bromo-5', 6'-didehydro-6'-deoxy-6'-fluorohomoadenosine (BDDFHA), which functions as a substrate for the "6'-hydrolytic activity" of the enzyme with subsequent formation of a covalent linkage with the enzyme. Incubation of human placental AdoHcy hydrolase with BDDFHA results in a maximum inactivation of 83% with the remaining enzyme activity exhibiting one-third of the kcat value of the native enzyme. This partial inactivation is concomitant with the release of both Br- and F- ions and the formation of adenine (Ade). The enzyme can be covalently labeled with [8-3H]BDDFHA, resulting in a stoichiometry of 2 mol of BDDFHA/mol of the tetrameric enzyme. The 3H-labeled enzyme retains its original NAD+/NADH content. Tryptic digestion and subsequent protein sequencing of the [8-3H]BDDFHA-labeled enzyme revealed that Arg196 is the residue that is associated with the radiolabeled inhibitor. The partition ratio of the Ade formation (nonlethal event) to covalent acylation (lethal event) is approximately 1:1. From these experimental results, a possible mechanism by which BDDFHA inactivates AdoHcy hdyrolase is proposed: enzyme-mediated water addition at the C-6' position of BDDFHA followed by elimination of Br- ion results in the formation of homoAdo 6'-carboxyl fluoride (HACF). HACF then partitions in two ways: (a) attack by a proximal nucleophile (Arg196) to form an amide bond after expulsion of F- ion (lethal event) or (b) depurination to form Ade and hexose-derived 6-carboxyl fluoride (HDCF), which is further hydrolyzed to hexose-derived 6-carboxylic acid (HDCA) and F- ion (nonlethal event).

Familial megacecum and colon in the rat: a new model of gastrointestinal neuromuscular dysfunction

Gastrointestinal motility disorders are of considerable clinical importance in humans and animals. Abnormalities of smooth muscle and the enteric nervous system have been described. We have identified and characterized a new mutant stock of rats that develops severe megacecum and colon with pseudo-obstruction, Familial Megacecum and Colon (FMC). The inheritance pattern of FMC was characterized by selective breeding. Gastrointestinal motility was evaluated radiographically. Complete pathologic evaluations, including ultrastructural examination and staining of colonic segments for acetylcholinesterase, peripherin, vasoactive intestinal peptide, substance P, nitric oxide synthase, and somatostatin, were performed. Spontaneous contractility and contractile force in isolated colonic muscle strips were examined. Familial megacecum and colon is inherited as an autosomal recessive trait. The markedly dilated cecum and proximal portion of the colon are followed by a short, funnel-shaped segment and distal portion of the colon with normal or slightly reduced lumen. Although clinical features and gross anatomic changes of the colon resemble those of Hirschsprung's disease in humans and animals, aganglionosis is not a feature of FMC. An increase in somatostatin staining was observed in dilated regions of bowel. The spontaneous contractile frequency and contractile force were diminished in the affected colon. Familial megacecum and colon is a new mutant, distinct from previously described hereditary and targeted mutant rodent models that develop megacecum and colon as a result of distal colonic dysfunction. The functional or morphologic defect(s) that result in colonic dysfunction in rats with FMC was not determined. The disease may result from an absence or overexpression of a single or group of neurotransmitters or their respective neurons, receptor abnormalities, or defects in the intestinal pacemaker system.

Effects of Erkang, a modified formulation of Chinese folk medicine Shi-Quan-Da-Bu-Tang, on mice

Shi-Quan-Da-Bu-Tang is a traditional Chinese herbal medicine formula used to increase vital energy, and strengthen health and immunity. Data from previous studies demonstrated that this formula also has the ability to attack tumor tissue. The Erkang capsule is a modified formula of Shi-Quan-Da-Bu-Tang, with the addition of four other herbs to increase the adaptogen effects and ergogenic properties. Results from this study in mice indicated that the Erkang treated group had significant differences in mortality, body weight change, fatigue, cold temperature endurance, and immune function related organ weight change, compared to the control animals.

Gut and brain effects of American ginseng root on brainstem neuronal activities in rats

Brainstem neurons receiving subdiaphragmatic vagal inputs were recorded in an in vitro neonatal rat brainstem-gastric preparation. Aqueous extracts of American ginseng root (Panax quinquefolium L.) were applied to the gastric compartment or the brainstem compartment of the bath chamber to evaluate the peripheral gut and central brain effects of the extracts on brainstem unitary activity. After Panax quinquefolium L. application to the gastric or brainstem compartment, a concentration-related inhibition in neuronal discharge frequency in the brainstem unitary activity was observed, suggesting that Panax quinquefolium L. may play an important role in regulating the digestive process and modulating brain function. In this study, pharmacological effects of American-cultivated Panax quinquefolium L. and Chinese-cultivated Panax quinquefolium L. were also compared. Our results suggest that American-cultivated Panax quinquefolium L. possesses a significantly stronger gastric modulating effect on brain neuronal activity.

Structure determination of selenomethionyl S-adenosylhomocysteine hydrolase using data at a single wavelength

S-Adenosylhomocysteine (AdoHcy) hydrolase regulates all adenosylmethionine-(AdoMet) dependent transmethylations by hydrolyzing the potent feedback inhibitor AdoHcy to homocysteine and adenosine. The crystallographic structure determination of a selenomethionyl-incorporated AdoHcy hydrolase inhibitor complex was accomplished using single wavelength anomalous diffraction data and the direct methods program, Snb v2.0, which produced the positions of all 30 crystallographically distinct selenium atoms. The mode of enzyme-cofactor binding is unique, requiring interactions from two protein monomers. An unusual dual role for a catalytic water molecule in the active site is revealed in the complex with the adenosine analog 2'-hydroxy, 3'-ketocyclopent-4'-enyladenine.