Analysis of hyperforin (St. John's wort) action at TRPC6 channel leads to the development of a new class of antidepressant drugs

St. John's wort is an herb, long used in folk medicine for the treatment of mild depression. Its antidepressant constituent, hyperforin, has properties such as chemical instability and induction of drug-drug interactions that preclude its use for individual pharmacotherapies. Here we identify the transient receptor potential canonical 6 channel (TRPC6) as a druggable target to control anxious and depressive behavior and as a requirement for hyperforin antidepressant action. We demonstrate that TRPC6 deficiency in mice not only results in anxious and depressive behavior, but also reduces excitability of hippocampal CA1 pyramidal neurons and dentate gyrus granule cells. Using electrophysiology and targeted mutagenesis, we show that hyperforin activates the channel via a specific binding motif at TRPC6. We performed an analysis of hyperforin action to develop a new antidepressant drug that uses the same TRPC6 target mechanism for its antidepressant action. We synthesized the hyperforin analog Hyp13, which shows similar binding to TRPC6 and recapitulates TRPC6-dependent anxiolytic and antidepressant effects in mice. Hyp13 does not activate pregnan-X-receptor (PXR) and thereby loses the potential to induce drug-drug interactions. This may provide a new approach to develop better treatments for depression, since depression remains one of the most treatment-resistant mental disorders, warranting the development of effective drugs based on naturally occurring compounds.

Efficacy and cognitive side effects of tiagabine and topiramate in patients with epilepsy

OBJECTIVE

Whereas the efficacy of the newer antiepileptic drugs (AEDs) is well established, there remain questions regarding their cognitive side effects. Therefore, we performed a comparative open randomized trial with TPM and TGB as add-on therapy, with particular consideration of cognition, mood, and health-related quality of life (HRQOL).

METHODS

Forty-one patients with refractory epilepsy were randomly assigned to one of the two treatment groups (TPM vs TGB) and received neuropsychological testing at baseline (T1), after titration (3 months, T2), and during the maintenance phase (another 3 months, T3). Tests included measures of intelligence, attention, working memory, episodic memory, language, and self-report questionnaires regarding mood and HRQOL. Twenty patients (8 TPM, 12 TGB) discontinued the trial for different reasons (no group difference).

RESULTS

Seizure outcome (intention-to-treat analysis) was comparably good in both groups (8.1% seizure free, 29.7% seizure reduction>50%). From baseline to after the titration paired sample t tests revealed significant deterioration in verbal fluency, language comprehension, working memory, and visual block tapping under TPM and a deterioration in verbal memory (delayed free recall) in the TGB group. These functions remained stable in the maintenance phase. Self-report measures initially indicated concerns about AED side effects in both groups and concerns about worse cognitive functioning and depression under TPM. In the maintenance phase the TGB group reported feeling a lack of energy, whereas patients on TPM demonstrated improvement on all QOLIE scales on a descriptive level.

CONCLUSION

This study demonstrates the comparable efficacy of TPM and TGB. Consistent with previous reports, TPM but not TGB appears to be associated with persistent negative cognitive side effects on frontal lobe-associated functions, the degree of which may be estimated by the fact that this effect was observed with a very small sample size. In contrast, in patients taking TPM, initially negatively affected HRQOL returns to baseline in the long run on a descriptive level. The latter finding may be interpreted in accordance with the observation that objective performance and subjective self-report under TPM can be dissociated.

A prospective randomized comparison of unsedated ultrathin versus standard esophagogastroduodenoscopy in routine outpatient gastroenterology practice: does it work better through the nose?

BACKGROUND AND STUDY AIMS

In an outpatient gastroenterological practice setting, highly effective diagnostic procedures and patient satisfaction play an important role. Ultrathin endoscopy in unsedated patients has been shown to be more cost-effective and time-efficient in comparison with standard endoscopy. A prospective randomized study was carried out in unsedated patients to compare performance, feasibility, safety, and patient tolerance between ultrathin transnasal (UT), ultrathin oral (UO), and standard (SO) esophagogastroduodenoscopy (EGD).

PATIENTS AND METHODS

A total of 200 of 600 eligible patients consented to participate in the study, and were randomly assigned to undergo UT, UO, or SO. Patients reported their tolerance of the procedure (anxiety, pain, gagging, and overall satisfaction; Likert scale 1-10), and the endoscopists reported the effectiveness of the procedure (handling, picture quality, and overall performance; Likert scale 1-10). Statistics were calculated using the Kruskal-Wallis test.

RESULTS

After randomization, 65, 67, and 68 patients were allocated to the UT, UO, and SO groups, respectively. Failure to achieve complete EGD by the intended route occurred in 14 patients (22 %) in the UT group. Compared to the SO group, patients in the UT and UO groups rated anxiety before the procedure as being more intense - median score (10 % quantile estimate; 90 % quantile estimate): UT, 2.0 (1.0; 4.0); UO, 2.0 (1.0; 4.0); SO, 0.0 (0.0; 2.0); p < 0.0001), whereas SO patients experienced a higher level of anxiety during the procedure ( P < 0.0001). Pain during insertion of the endoscope was the least intense in the UO group: UT, 2.0 (1.0; 5.0); UO, 1.0 (1.0; 3.0); SO, 2.0 (1.0; 4.0); P < 0.001). Gagging during insertion was more pronounced in the UO group: UT, 2.0 (1.0; 4.0); UO, 3.0 (1.0; 7.0); SO, 2.0 (1.0; 5.0); P < 0.01). The patients' score for the overall assessment was better in the SO group ( P < 0.0001). The endoscopists' overall assessment for ultrathin EGD was poorer than for standard EGD: UT, 3.0 (2.0; 5.0); UO, 3.0 (2.0; 5.0); SO, 2.0 (1.0; 3.0); P < 0.0001).

CONCLUSIONS

Ultrathin endoscopy through both the transnasal and oral routes has limited use in routine outpatient practice. Techniques for reducing pain and gagging may improve patient tolerance. Further technical improvements are needed to allow routine implementation.

[Compliance with terminology standards in reflux, ulcers, and gastritis: A study of 881 consecutive upper gastrointestinal endoscopy reports]

BACKGROUND

The German version of the Minimal Standard Terminology document for endoscopy was discussed in 1997 and 1998, and finally published at the end of 1999 as one of the German Gastroenterology Society guidelines. The diagnoses and descriptive terms included in this standard terminology are based on the consensus views of a large number of German endoscopists (20 endoscopists based in Munich and 20 elsewhere in Germany). The aim of the present study was to investigate how much spontaneous compliance there is with the descriptive terms included in the standard terminology - both among the members of the consensus discussions, and among colleagues not involved in this project.

METHODS

A total of 881 endoscopy reports with the diagnoses of reflux, ulcer, and gastritis were collected from 11 centers (2 hospitals and 9 private offices, with a total of 26 examiners) over a one-month period. Nine of the 26 examiners were actively involved in the terminology consensus discussion. The rate of occurrence of the descriptive terms contained in the standard terminology was assessed for the diagnoses listed above.

RESULTS

Compliance with the descriptive terms was high (> 90 %) only for basic parameters such as the Savary classification of reflux and the area in which gastroduodenal ulcers were located. Other important parameters, such as the extent (length) of Barrett's esophagus, ulcer size, and circumferential location, were reported in only three-quarters of cases or less. The descriptions of gastritis were inconsistent. There was no difference in the degree of compliance either between endoscopists using free dictation and those using computerized text blocks, or between members of the terminology group and those not involved in preparing the terminology.

CONCLUSIONS

Adherence to standard terminology and its descriptive parameters is poor even among specialized gastroenterologists who have been involved in terminology consensus discussions. Compliance needs to be improved by providing suitable software programs with automatic reporting functions.

A new system for rapid large-caliber percutaneous transhepatic drainage in patients with obstructive jaundice: a prospective randomized trial

BACKGROUND AND STUDY, AIMS: Percutaneous access to the biliary tract is an important diagnostic and therapeutic tool in the management of biliary diseases. It is usually chosen when the endoscopic approach via endoscopic retrograde cholangiopancreatography (ERCP) fails, or is not possible. Once established, the percutaneous tract is then used for the treatment of biliary stones and strictures. To establish a percutaneous tract with a caliber large enough for cholangioscopy to be performed, or for a large-bore permanent drainage tube to be inserted, stepwise dilation up to 14 Fr or 16 Fr is usually required. We present here a new method of rapid dilation using specially designed materials, including a stiffenable guide wire and specially adapted bougies.

PATIENTS AND METHODS

Consecutive patients undergoing percutaneous drainage for biliary diseases were included in this prospective study, over a 19-month period. After establishment of a 10-Fr transpapillary drain, the patients were randomly assigned to either conventional percutaneous transhepatic biliary drainage (PTBD) or stepwise dilation using the new method, aiming at a need for only one further session, using a specially designed stiffenable metal guide wire of 6.6 Fr and plastic bougies. The details of the procedure (duration, materials used, technical ease), initial and later complications, assessment by the patients, and procedural costs were compared between the two groups.

RESULTS

Of the 60 patients included, 29 were randomly assigned to group I (the new method) and 31 to group II (the conventional approach); there were no significant differences between the two groups in terms of clinical data or biliary pathology. The clinical efficacy of PTBD was similar in the two groups, although three patients in group II were switched to the new procedure because of failure of dilation using the conventional approach. The rates of major complications (four of 29 in group I, five of 31 in group II) and patient tolerance were also similar. However, the new procedure led to a significant reduction in the cumulative procedure duration (20.1 minutes vs 30.1 minutes), mean number of sessions (1.1 vs. 1.7), and mean number of hospital days (2.0 vs 5.5), and was therefore also cost-effective, reducing costs from a mean of 5813 to 2581 German marks (DM) per patient.

CONCLUSIONS

The new system for rapid establishment of large-caliber PTBD offers significant advantages in terms of saving hospital resources while maintaining clinical efficacy.

Are guidelines followed in Helicobacter pylori diagnosis and therapy? An inquiry among gastroenterologists, referring physicians and patients in Munich

BACKGROUND AND STUDY AIMS

Attempts to standardize Helicobacter pylori (Hp) diagnosis and therapy have led to the publication of guidelines by various national gastroenterological societies in Europe and the USA. However, little information is available either regarding the compliance of gastroenterologists and referring physicians with these guidelines, or regarding the patients' perspective.

PATIENTS AND METHODS

A retrospective analysis was conducted of all outpatient upper gastrointestinal endoscopy reports for a one-month period in eleven different centers (two university hospitals and nine private practice gastroenterology offices) with a total of 24 gastroenterologists. Endoscopy reports from patients wit the indications of reflux, diarrhea, and tumors were excluded. Diagnoses and treatment recommendations given by gastroenterologists were recorded. Questionnaires concerning Hp diagnosis, treatment indications and performance, and follow-up were sent to referring physicians and patients.

RESULTS

A total of 772 endoscopy reports were included in the study; analyzable questionnaires were returned by 287 referring physicians (47%) and by 265 patients (59%). Gastroenterologists recommended Hp eradication in all ulcers and in 29% of gastritis/nonulcer dyspepsia (NUD) cases. Referring physicians thought that 94% of ulcers should be treated by Hp eradication, which was also considered to be an absolute and relative indication in NUD by 15% and 53% of the referring physicians, respectively. Among the patients who replied, 52% had received Hp eradication regimens; ulcers were found in 22% of the total patient group. Check-up examinations after Hp therapy were considered necessary by 75% of the referring physicians, but only 22% of the responding patients actually underwent some form of check-up (upper gastrointestinal endoscopy in 91%).

CONCLUSIONS

Gastroenterologists and (to a somewhat lesser extent) referring physician appear to be following the current guidelines for Hp treatment. As expected, two thirds of referring physicians consider NUD to be absolute or relative indication for Hp eradication. Check-up examinations are apparently being performed less frequently than recommended.

Biochemical organization of single motor units in two multi-tendoned muscles of the cat distal forelimb

In anesthetized cats single motor units (MUs) of the extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) muscles were selectively activated by stimulation of cervical ventral root filaments. The distribution of force developed by single MUs at the four distal tendons of the EDC muscle and at three portions of the distal tendon of the ECU muscle was analysed. In general, single MUs of both muscles distributed force over all tendons in a unimodal pattern, with the maximal force levels generated at one specific tendon which was termed the best-tendon. Distributions of force were quantitatively described by a parameter representing the mean direction of force output (output-index) and a further one representing the dispersion of force over the distal tendons (divergence). Generally, these parameters and the best-tendon remained stable when a MU was stimulated at different frequencies, but varied from MU to MU. Despite the general stability of the force distribution, slight systematic changes were regularly found in EDC MUs, when they developed a higher amount of force due to a higher frequency of stimulation: the relative amount of force at the best-tendon increased; e.g. the MUs got more selective for the best-tendon. These changes were partly due to overcoming mechanical cross-coupling between neighbouring compartments of the EDC muscle. Such changes of force distribution were only found in a part of the ECU MUs; other ECU MUs did not change their force distribution at all or became less selective for the best-tendon. The phenomenon that MUs of multi-tendoned muscles distribute their force output to the distal tendons in specific patterns is probably due to mechanical partitioning of the parent muscles: the localization of spatial territories of MUs within different anatomical muscle compartments should correspond to the best-tendon. Complex mechanisms allowing passive transmission of force from limited territories along the transverse axis of both muscles must be assumed in order to explain why most MUs act on all tendons and why force distributions change with increasing stimulus frequency. In addition, specific relations between unit type and force distributions were found within both muscles. Fatigue-resistant EDC MUs have broader force distributions than fatigue-sensitive EDC MUs and slow ECU MUs were found to act predominantly on the most ulnar part of the distal tendon. These biomechanical properties of MUs are discussed as supporting the specific functions of the respective muscles.

Contractile properties of single motor units in two multi-tendoned muscles of the cat distal forelimb

The contractile properties of motor units (MUs) in two multi-tendoned forelimb muscles were investigated. In anesthetized cats single MUs of the extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) muscles were selectively activated by stimulation of cervical ventral root filaments. MUs were characterized by various tests including single twitches, series of tetanic contractions providing a tension-frequency relation and a fatigue test. They were classified by the parameters contraction time (CT, time-to-peak within unpotentiated single twitches) and fatigue-index (RB, according to Burke). The ECU muscle is composed of 38% type FR MUs (fast, fatigue-sensitive; CT less than 38 ms; RB less than 0.5), 35% type FR MUs (CT less than 38 ms, RB greater than 0.5) and 27% type S MUs (slow; CT greater than 38 ms, RB greater than 0.5). 46% of the EDC MUs were classified as FF (RB less than or equal to 0.25), 29% as FI (fast, intermediately fatiguable; 0.25 less than RB less than 0.75) and 25% as FR/S (fatigue-resistant, fast or slow; RB greater than or equal to 0.75). The latter group was devised since most MUs appeared as fast and the unequivocal presence of slow MUs could neither be demonstrated nor excluded. Normalized tension-frequency relations of fast ECU and EDC MUs were nearly identical and similar to those reported for fast MUs of other muscles. In contrast to this, the tension-frequency relation of slow ECU MUs has a different shape supporting the use of this function to distinguish fast from slow MUs. The distribution of different types of MUs is discussed with regard to the structure and function of the parent muscles and in relation to hindlimb muscles of comparable architecture. As revealed by comparison to EMG data gained in behaving animals (Fritz et al. 1985; Hoffmann et al. 1986, Botterman et al. 1985), the three muscles of the cat distal forelimb investigated so far seem to be adapted to different tasks: the EDC to rapid movements with a high proportion of type FF MUs, flexor carpi radialis to sustained contractions during the body support with a high proportion of fatigue-resistant MUs; the ECU which changes synergism between both muscles has an intermediate composition.

Pattern of monosynaptic Ia connections in the cat forelimb

1. In anaesthetized cats intracellular records were obtained from antidromically identified motoneurones. The motor nuclei to the elbow extensor and flexor muscles and to the muscles innervated by the deep radial, ulnar and median nerves were investigated. The maximum Ia EPSPs from electrical stimulation of various peripheral nerves were measured. The characteristic convergence and projection patterns to each motor nucleus were established from pooled data. 2. The total aggregates of the Ia EPSPs between the different motor nuclei ranged from 3.5 to 11.7 mV. The smallest aggregates were found in the nuclei to the digit muscles. The ratio of the heteronymous versus homonymous EPSP amplitudes varied between 3.9 and 0.5. A general rule which would govern the distribution of the EPSP aggregates, such as a proximo-distal gradient, was not observed. 3. The Ia connections followed a complex but highly organized pattern. Bidirectional and unidirectional pathways were present. In many cases the convergence pattern of a motor nucleus included muscles acting at different joints. The connections of one nucleus were not necessarily restricted to one side of the limb, but could cross the radio-ulnar plane. 4. Muscles with similar actions onto the same joint were interconnected with bidirectional, rather balanced Ia pathways. Such relations were also present between close functional synergists and then often extended across several joints. The relations between the anatomical extensors of wrist and digits were graded according to the neighbourhood of these muscles. It is suggested that this reflects the graded mechanical synergism in the wrist action of these muscles. 5. A large number of unidirectional or strongly skewed bidirectional Ia pathways project from proximal to distal muscles. It is suggested that they may serve a readjustment of distal joints during changes in the position of proximal ones (e.g. stabilization of the position of the radio-ulnar plane during elbow extension in case of the undirectional projections onto supinator and abductor pollicis longus motoneurones). 6. The motor nuclei to some multifunctional muscles display a negative correlation between different heteronymous Ia inputs: motoneurones with a large input from one muscle show a significant tendency to receive a smaller input from another muscle and vice versa. This organization leads to subpopulations of neurones with different convergence patterns within the same motor nucleus. 7. Motor nuclei with bidirectional Ia relations between each other displayed similar convergence and projection patterns. They were combined into 'Ia synergistic groups.' One motor nucleus may belong to several groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Location of motoneurones projecting to the cat distal forelimb. I. Deep radial motornuclei

The position of the motornuclei projecting through the dorsal interosseus (DR) nerve to the distal forelimb muscles has been investigated in the cat. Horseradish peroxidase (HRP) and fluorescent (Fl) compounds have been used as retrograde tracers. They were either injected into forelimb muscles or applied to the proximal end of transected forelimb nerves. Limb muscles that were not investigated have been carefully denervated. HRP was used to trace the position and the architecture of the individual motornuclei. The topographical relations between the nuclei were established with application of up to three F compounds in the same animal. The position of the labeled motornuclei was reconstructed with a computer-assisted approach which is described in the appendix. The DR representation area extends from the caudal C5 to the caudal Th1 segments. In C6 it forms a dorsoventrally oriented narrow region at the lateral border of the ventral horn; in C7 and rostral C8 it forms a broad column in the dorsolateral corner of the ventral horn. In caudal C8 and Th1 this column is shifted into a ventral direction. The motoneurones projecting to the individual DR muscles are not randomly distributed in this area, but arranged in long, slender columns. These motornuclei occupy specific positions with only minimal interindividual variations. Three nuclei (brachioradialis, extensor carpi radialis, and supinator) are located in the C6 and C7 segments. They compose about one-third of the DR cell population. The nuclei to the other radial muscles are all located in C8 and Th1. Thus most of the DR motoneurones are located in these two segments. These results, together with those from the companion paper on the location of the median and ulnar motornuclei, provide important anatomical knowledge for the investigation of the cat brachial enlargement.

Location of motoneurones projecting to the cat distal forelimb. II. Median and ulnar motornuclei

The position of the motornuclei projecting through the median (Mn) and ulnar (Ul) nerves to the cat distal forelimb has been investigated. Horseradish peroxidase (HRP) and fluorescent (Fl) compounds have been used as retrograde tracers. They were either injected into forelimb muscles or applied to the proximal end of transected forelimb nerves. Limb muscles that were not investigated were carefully denervated. The position and the architecture of the individual motornuclei were traced with HRP. The topographical relations between the nuclei were established with application of up to three different Fl compounds in the same animal. The Mn motoneurones had a bimodal distribution in the brachial spinal cord. The motoneurones to the pronator teres and flexor carpi radialis muscles were located in C7 and the other Mn motoneurones were located in C8 and Th1. In C7 the Mn motoneurones occupied a single representation area, which is located some distance medially of the lateral funiculus. In C8 and Th1 two Mn representation areas were found: A dorsal one that contacts the lateral funiculus and is located at the level of the central canal; a ventral one that is located ventrally in the ventral horn. The dorsal area is occupied by the motornuclei projecting to the intrinsic hand muscles and the ventral one by the nuclei projecting to the limb. The Ul motoneurones extend with an unimodal distribution from the caudal C7 to the caudal Th1 segments. They occupy a single, broad representation area. The dorsal part, which contacts the lateral funiculus, is located at the level of the central canal and harbours the nuclei to the intrinsic hand muscles. The other Ul nuclei are located ventromedially deep in the ventral horn. These results, together with those from the companion paper on the location of the deep radial motornuclei, provide important anatomical information for the investigation of the cat brachial enlargement.

Fluorescent compounds as retrograde tracers compared with horseradish peroxidase (HRP). II. A parametric study in the peripheral motor system of the cat

Fluorescent compounds which are currently used as retrograde tracers were tested in the cat peripheral motor system and compared with horseradish peroxidase (HRP). The tracers were either injected into forelimb muscles or applied to the proximal end of transected forelimb nerves. The remaining muscles of the limb has been carefully denervated. Following intramuscular injection all fluorescent compounds labeled spinal cord motoneurons, the DAPI compounds labeled endothelial cells in addition. In the nerve application mode tracer positive motoneurons were only observed when propidium iodide (PI) and the DAPI compounds were used, whereas bisbenzimide (BB), nuclear yellow (NY) and primuline did not label any cells. The fluorescence of BB labeled motoneurons were predominantly located in the cytoplasma. NY positive motoneurons showed a different localization of the fluorescent label between the different neurons of the same motornucleus: in some neurons it was exclusively located in the nucleus, in others predominantly in the cytoplasma, in the majority in both compartments. The intracellular distribution of the BB and the NY label was independent of the pH of the fixation fluid. The fluorescent tracers labeled the motoneuronal cell columns in their complete rostrocaudal extent and in a position identical to the one obtained with HRP. However, some substances (PI, fast blue) labeled less motoneurons of a motornucleus than did HRP, none of the fluorescent tracers labeled more. The results are discussed under several aspects: use of the investigated fluorescent compounds as single tracers; use of several tracers in the same animal to map collateral projections of one and the same neuron; use of several tracers in the same animal to establish the topographical relation between several independent neuronal populations.

Location of median and ulnar motornuclei in the cat

In the cat we used the horseradish peroxidase (HRP) technique to investigate the location of the motor nuclei projecting through the median and the ulnar nerves. Each nucleus is described b its longitudinal extent along the rostro-caudal spinal cord axis and by its dorso-ventral and medio-lateral position within the ventral horn. The topographical relations between different nuclei are, however, only provisionally ascertained with the HRP technique, since the simultaneous use of different fluorescent tracers in the same animal is a more powerful approach to establish the spatial relations between different neuronal populations. One example with the latter technique is reported, which demonstrates the complete overlap of two different nuclei.

Location of dorsal interosseus motor nuclei in the cat

In the cat we have investigated the position of the motor nuclei projecting through the dorsal interosseus nerve to the distal forelimb muscles. Horseradish peroxidase was either injected into single muscles or applied to the central end of a cut nerve. The location of each nucleus is described in two ways: histograms giving the distribution of the labelled motoneurones along the rostro-caudal spinal cord axis; and regions in reconstructed cross-sections of the ventral horn which indicate the area occupied by the motoneurones of one nucleus. The relation between the nuclei was established by superposition of the reconstructed cross-sections. With this procedure we have obtained a map which shows the positions of the centres of the single radial nuclei.