Effects of riluzole on electrically evoked neurotransmitter release

1. The main purpose of the present study was to investigate the effects of the neuroprotective agent riluzole on the electrically evoked release of [(3)H]-glutamate ([(3)H]-Glu) in mouse neocortical slices. The reported selectivity of riluzole for excitatory amino acids was tested in release experiments with further neurotransmitters. Also distinct species, mouse, rat and man were compared. 2. [(3)H]-Glu was formed endogenously during incubation of slices with [(3)H]-glutamine ([(3)H]-Gln). Released [(3)H]-Glu and tissue [(3)H]-Glu was separated by anion exchange chromatography. Electrically evoked [(3)H]-Glu release was strongly diminished by tetrodotoxin (TTX) and Ca(2+)-withdrawal. 3. Riluzole (100 microM) depressed the release of [(3)H]-Glu up to 77% (IC(50)=19.5 microM). Riluzole was also able to inhibit strongly the electrically evoked release of [(3)H]-acetylcholine ([(3)H]-ACh) (at 100 microM by 92%, IC(50)=3.3 microM, and [(3)H]-dopamine ([(3)H]-DA) (at 32 microM by 72%, IC(50)=6.8 microM). However, the release of [(3)H]-serotonin ([(3)H]-5-HT) was less diminished (at 100 microM by 53%, IC(50)=39.8 microM). Riluzole up to 100 microM did not affect [(3)H]-noradrenaline ([(3)H]-NA) release. 4. Between species, i.e. in mouse, rat and human neocortex, no significant differences between the effects of riluzole could be observed. 5. The NMDA-receptor blocker MK-801 (1 microM) and the AMPA/Kainate-receptor blocker NBQX (1 microM) did neither affect the electrically evoked [(3)H]-ACh release nor its inhibition by riluzole, indicating that effects of riluzole on transmitter release were neither due to modulation of ionotropic Glu receptors, nor due to indirect inhibition of Glu release through these receptors. 6. Taken together, riluzole inhibits the release of distinct neurotransmitters differently, but is not selective for the excitatory amino acid Glu.

A new primate model for multiple sclerosis in the common marmoset

Experimental autoimmune encephalomyelitis (EAE) in outbred marmoset monkeys (Callithrix jacchus) is a recently developed nonhuman primate model of multiple sclerosis. Here, Bert 't Hart and colleagues compare this model to EAE in rhesus monkeys, highlighting autoimmune mechanisms in CNS inflammation and demyelination, including the role of major histocompatibility complex restriction and preclinical evaluation of innovative immunotherapies.

Physicochemical characteristics of triacyl lipid A partial structure OM-174 in relation to biological activity

The triacylated lipid A partial structure OM-174 was characterized in detail using a variety of physical and biological techniques. OM-174 aggregates adopt the micellar HI structure. The temperature (Tc) of the gel to liquid-crystalline phase transition of the hydrocarbon chains is 0 degrees C, from which high fluidity of the acyl chains at 37 degrees C can be deduced. The molecular area of a single OM-174 molecule at a surface pressure of 30 mN x m-1 is 0.78 +/- 0.04 nm2. Conformational analyses, using IR spectroscopy, of the behavior of the various functional groups of OM-174 as compared with hexa-acyl lipid A suggest altered hydration of the phosphate charges and unusually strong hydration of the ester groups, which is probably related to the high accessibility of these groups to water in the micellar aggregate structure. OM-174 was shown to intercalate into a phospholipid membrane corresponding to the macrophage membrane within seconds in the presence, and within minutes to hours in the absence, of LPS-binding protein. In the Limulus amebocyte lysate assay, the triacyl lipid A is more than 105-fold less active than hexa-acyl lipid A, but only 10-fold less active in inducing IL-6 in human mononuclear cells, and equally active in inducing NO production in murine macrophages. These findings are used to explain the mechanism of the lipid A-induced cell activation.

[Topiramate (Topamax). Pharmacological characteristics and current use in epilepsy treatment]

Topiramate (Topamax) has been registered since July 1998 and has market authorization for the Federal Republic of Germany as an additive drug for the treatment of patients (age 12 or older) suffering from intractable partial and secondarily generalized seizures. The anticonvulsant effect of topiramate is based on three mechanisms: (a) modulating the blocking of the Na channels activated by voltage, depending on status, (b) potentiation of GABAA-mediated inhibiting neurotransmission, and (c) inhibition of excitatory neurotransmission by blocking APMA glutamate receptors. Topiramate exhibits a substantial anticonvulsive effect on partial seizures both with and without secondary generalization. The median reduction in seizure frequency using topiramate as adjunct therapy was 44%. In 44% of patients, seizure frequency was reduced by more than 50%, and seizure reduction was more than 75% in nearly half of these (i.e., in 21% of all patients), while 5% of patients remained completely free of seizures. Adverse events most often caused central nervous disturbances. Weight loss, the development of renal calculi, and impairment of cognitive functions may occur. It is recommended to start therapy with topiramate at a daily dosage of 25 mg, increasing by 25 mg every week up to 200-400 mg/day but not exceeding 1000 mg/day.

Hypoxia-induced tumour cell migration in an in vivo chicken model

To investigate the relationship between hypoxia, neovascularisation and tumour cell spread, experiments on the area vasculosa of the early chick embryo under different oxygen concentrations were performed in vivo. Human glioblastoma cells (U-138MG) were inoculated onto the area vasculosa and the fertilised eggs were incubated under conditions of normoxia or hypoxia. For evaluation, we performed in vivo video-microscopy of the area vasculosa and determination of microvessel density (MVD), as well as a histological examination of the fixed specimen. Under hypoxia, MVD was significantly increased compared to normoxic conditions. Only under hypoxic conditions was tumour cell spread found outside the main tumour mass and within the vessels, at times followed by the subsequent development of secondary tumour cell bulks on the area vasculosa. These data lead to the conclusion that hypoxia can stimulate tumour cell migration in this in vivo model.

Mycotic pseudoaneurysm of the aorta in children

Mycotic pseudoaneurysm of the aorta is a rare disease in childhood. We report on two cases which were diagnosed in an unselected general pediatric population within an 8-month period. The first case was a 16-month-old toddler with a normal cardiac history who presented with purulent pericarditis due to group A streptococcus and subsequent pseudoaneurysm formation of the ascending aorta while convalescing from varicella infection. The second case was a 14-year-old girl with a previously undiagnosed coarctation of the aorta who developed a Staphylococcus aureus aortitis in the dilated poststenotic segment with pseudoaneurysm formation and infiltration into the adjacent lung tissue. In both cases parenteral antibiotic therapy was administered over 10 and 4 days, respectively, followed by emergency surgery consisting of aneurysmectomy, coarctectomy (case 2), and in situ homograft implantation. Recovery was uneventful. In both cases early institution of a femorofemoral cardiopulmonary bypass prevented a fatal outcome despite intraoperative rupture of the pseudoaneurysm.

A prospective evaluation of the clinical value of nation-wide DNA fingerprinting of tuberculosis isolates in Denmark

SETTING

Denmark, a country with a low incidence of tuberculosis (TB).

OBJECTIVE

To evaluate the value of the nation-wide DNA fingerprinting of Mycobacterium tuberculosis isolates performed in Denmark since 1992.

DESIGN

Prospective study of consecutive patients with culture-verified TB from five large TB Departments in Denmark during a 7-month period in 1998. Results of IS6110 RFLP and spoligotyping were compared to those in the nation-wide Danish DNA-fingerprint database which covers approximately 95% of all culture-verified TB cases from 1992 onwards. Questionnaires asking about contact tracing and epidemiological links were sent to the patients' treating physicians.

RESULTS

Of the 177 patients included in the study, 57 were Danes, one was from Iceland, 111 were immigrants, and eight were from Greenland. Responses to the questionnaires were obtained from 163 patients (92%). Four cases of unsuspected transmission were detected: one of nosocomial spread of TB, one of occupational acquisition of TB and two of transmission in an international school, leading to further contact tracing among 75 schoolchildren. These four cases were all the result of short-term contacts. In 22 cases, contact with one or more TB patient(s) was reported. In six of these, the DNA-fingerprint result revealed that the presumed contact could not be the source of infection, even though in two of the cases the known TB contact was from the household.

CONCLUSION

Nation-wide DNA fingerprinting of TB isolates provides information that could not have been obtained otherwise, and contribute to the understanding of TB transmission in Danish society. In some cases the results lead to further contact tracing. Short-term contact can apparently result in transmission of TB.

Electrophoresis in space

Programs for free flow electrophoresis in microgravity over the past 25 years are reviewed. Several studies accomplished during 20 spaceflight missions have demonstrated that sample throughput is significantly higher in microgravity than on the ground. Some studies have shown that resolution is also increased. However, many cell separation trials have fallen victim to difficulties associated with experimenting in the microgravity environment such as microbial contamination, air bubbles in electrophoresis chambers, and inadequate facilities for maintaining cells before and after separation. Recent studies suggest that the charge density of cells at their surface may also be modified in microgravity. If this result is confirmed, a further cellular mechanism of "sensing" the low gravity environment will have been found. Several free fluid electrophoresis devices are now available. Most have been tried at least once in microgravity. Newer units not yet tested in spaceflight have been designed to accommodate problems associated with space processing. The USCEPS device and the Japanese FFEU device are specifically designed for sterile operations, whereas the Octopus device is designed to reduce electroosmotic and electrohydrodynamic effects, which become dominant and detrimental in microgravity. Some of these devices will also separate proteins by zone electrophoresis, isotachophoresis, or isoelectric focusing in a single unit. Separation experiments with standard test particles are useful and necessary for testing and optimizing new space hardware. A cohesive free fluid electrophoresis program in the future will obviously require (1) flight opportunities and funding, (2) identification of suitable cellular and macromolecular candidate samples, and (3) provision of a proper interface of electrophoresis processing equipment with biotechnological facilities--equipment like bioreactors and protein crystal growth chambers. The authors feel that such capabilities will lead to the production of commercially useful quantities of target products and to an accumulation of new knowledge relating to the complexities of electrostatic phenomena at the cell surface.

Expression of 5alpha-reductase and 3alpha-hydroxisteroid oxidoreductase in the hippocampus of patients with chronic temporal lobe epilepsy

PURPOSE

The hippocampus is one of the principal target areas for neurosteroidal action, and the major neuroendocrine conversion of progesterone appears to be 5alpha-reduction and 3alpha-hydroxysteroid oxidoreduction, leading to the potent neurosteroid 3alpha,5alpha-tetrahydroxyprogesterone. To investigate whether the human hippocampus is equipped with the enzymes 5alpha-reductase and 3alpha-hydroxysteroid oxidoreductase (3alpha-HSOR), we studied the expression of 5alpha-reductase types 1 and 2 and 3alpha-HSOR types 1 and 2 in the resected hippocampi of patients with medically intractable chronic temporal lobe epilepsy.

METHODS

We studied tissue specimens from the hippocampi of 13 women, 25 men, and four children. Quantification of different mRNAs was achieved by competitive reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

5Alpha-reductase 1 mRNA and 3alpha-HSOR 2 mRNA were expressed in hippocampi of children and adults, whereas 5alpha-reductase 2 mRNA and 3alpha-HSOR 1 mRNA were not expressed. Neither 5alpha-reductase 1 mRNA nor 3alpha-HSOR 2 mRNA concentrations in hippocampal tissue showed any statistically significant differences between women and men or between children and adults.

CONCLUSIONS

This study demonstrates for the first time mRNA expression of the type 1 isozyme of 5alpha-reductase and the type 2 isozyme of 3alpha-HSOR in the human hippocampus. The finding that both 5alpha-reductase and 3alpha-HSOR are present in the hippocampus leads us to assume the synthesis of neuroactive steroids in this human brain area.

Response and palliation in a phase II trial of gemcitabine in hormone-refractory metastatic prostatic carcinoma. Swiss Group for Clinical Cancer Research (SAKK)

BACKGROUND

In a phase II trial, 43 patients with hormone-refractory prostate cancer were treated with gemcitabine at a dose of 1,200 mg/m2 over 2 hours (later decreased to 1,000 mg/m2 due to hematological toxicity) on days 1, 8 and 15 of a 28 day cycle.

PATIENTS AND METHODS

Inclusion criteria were proven tumor progression after hormonal treatment and increased PSA levels, a WHO PS < or = 2, adequate bone marrow reserve, liver and renal function and age < or =, 80 years. Response criteria were based on PSA levels (CR: normalization of PSA, PR: > 50% decrease). Quality of life (QL) was assessed with the EORTC QLQ-C30 on day 1 of each treatment cycle and on day 8 of the first cycle (range of scales 0-100). Physician-rated pain intensity and use of pain medication were assessed at the same timepoints.

RESULTS

Hematological toxicity of gemcitabine led to a dose-reduction in 48% of all cycles. Three of forty-three patients (RR = 7%) showed a PSA response: one CR and three PR with time to treatment failure of 8.7, 6.6 and > or = 9.3 months. Seven patients (16%) had stable disease (NC) for a median duration of 7.1 months (range 6.1-11.7 months). There was one case with objective regression of lymph node metastases. Patients reported a considerably impaired health status/QL (n = 41, median = 50) and severe fatigue (n = 41, median = 55.6) at baseline, with no change under treatment. Pain (QLQ-C30) was also severe at baseline (N=41, median=50) but was improved at the end of cycles 1 (n = 33, median change = -16.7, P = 0.0002), 2 (n = 19, median change = -33.3, P = 0.0006), 3 (n = 14, median change = -16.7, P = 0.06) and 4 (n = 9, median change = -33.3, P = 0.04). Patient-rated pain and use of analgesics as combined endpoint yielded palliation for at least 8 weeks in 14 patients (32%). Nine of these patients showed at least stable disease (CR/PR or NC by PSA level), five indicated a benefit in spite of progressive disease.

CONCLUSIONS

Gemcitabine in the dose and schedule indicated above has a significant beneficial impact on pain in patients with hormone-refractory prostatic carcinoma despite its limited activity in terms of PSA response and considerable, especially hematological, toxicity.

[Therapy of generalized tonic-clonic status epilepticus in adulthood]

If continuous seizure activity lasts longer than 5 minutes generalized tonic-clonic seizures require prompt treatment, if significant morbidity and mortality are to be avoided. The mortality varies (mean: 20%) depending on patient age and etiology. Control of status epilepticus is achieved by benzodiazepines in about 80% of cases: Lorazepam is recommended due to its longer-acting effects on the central nervous system. To maintain the anticonvulsive effect phenytoin is usually administered intravenously. Fosphenytoin (not approved in Germany) has advantages over phenytoin, because it can be given three times more rapidly and produces fewer side effects. The IV use of valproic acid in status epilepticus seems to be promising, but needs further evaluation. There is no generally accepted treatment protocol for the therapy of persistent seizure activity lasting more than 60 minutes (i.e., refractory status epilepticus). Usually phenobarbital, or general anesthesia with thiopental or pentobarbital are treatment recommendations. In recent reports, the administration of midazolam or propofol proved to be effective and well-tolerated.

The major protein import receptor of plastids is essential for chloroplast biogenesis

Light triggers the developmental programme in plants that leads to the production of photosynthetically active chloroplasts from non-photosynthetic proplastids. During this chloroplast biogenesis, the photosynthetic apparatus is rapidly assembled, mostly from nuclear-encoded imported proteins, which are synthesized in the cytosol as precursors with cleavable amino-terminal targeting sequences called transit sequences. Protein translocon complexes at the outer (Toc complex) and inner (Tic complex) envelope membranes recognize these transit sequences, leading to the precursors being imported. The Toc complex in the pea consists of three major components, Toc75, Toc34 and Toc159 (formerly termed Toc86). Toc159, which is an integral membrane GTPase, functions as a transit-sequence receptor. Here we show that Arabidopsis thaliana Toc159 (atToc159) is essential for the biogenesis of chloroplasts. In an Arabidopsis mutant (ppi2) that lacks atToc159, photosynthetic proteins that are normally abundant are transcriptionally repressed, and are found in much smaller amounts in the plastids, although ppi2 does not affect either the expression or the import of less abundant non-photosynthetic plastid proteins. These findings indicate that atToc159 is required for the quantitative import of photosynthetic proteins. Two proteins that are related to atToc159 (atToc120 and atToc132) probably help to maintain basal protein import in ppi2, and so constitute components of alternative, atToc159-independent import pathways.

Application of binary buffer systems to free flow cell electrophoresis

The applicability of free flow electrophoresis (FFE) was expanded towards processing of sensitive cells. The chamber medium was adjusted to a physiologic pH of 7.35 by a mixture of N-(2-hydroxyethyl)piperazine-N'-(3-propanesulfonic acid) (EPPS) and 2,2-bis(hydroxymethyl)-2,2'2"-nitrilotriethanol (BISTRIS). These substances proved to be nontoxic to sensitive cells such as human smooth muscle or thyroid cells. They enhanced the electrical conductivity of the medium only slightly so that a new cell electrophoresis separation medium could be prepared, which contained 30 mM NaCl together with or without 1 mM CaCl2 but did not generate problems of overheating the fluid. Suspended in this medium, human smooth muscle cells as well as human thyroid carcinoma cells remained viable single cells for at least 120 min. After this period they could be recultured to form monolayers. If electrophoresed in the Octopus preparative FFE device, they migrated as single cells and did not clot; therefore, their electrophoretic behavior could be determined exactly.

Interpreting DNA fingerprint clusters of Mycobacterium tuberculosis. European Concerted Action on Molecular Epidemiology and Control of Tuberculosis

Many studies of tuberculosis have defined clusters of patients on the basis of shared DNA fingerprint patterns of their Mycobacterium tuberculosis isolates. Clustering has been equated with recent transmission, and factors associated with clustering have been sought as a guide to population subgroups with high rates of ongoing transmission of M. tuberculosis. Considerable caution should be exercised in conducting and interpreting these studies. Groups of strains may be identical for reasons other than recent transmission, depending, for example, on the stability of the marker and the number of strains in the population over time. Cases actually due to recent transmission may not be seen as clustered if they are new immigrants to the population or if not all cases in the population are included in the study. The amount of clustering seen will depend on the duration of the study. Studies should give precise information on the study setting, the proportion of cases included, the recruitment period and the definition of clustering used. The data on clustering should be disaggregated at least by age, sex and immigration status. To be maximally informative, studies should involve a high proportion of all cases in a population, be conducted in conjunction with conventional epidemiological investigations of contacts (if possible), and should provide information on tuberculosis incidence in the population and on patients' age, sex, human immunodeficiency virus status, drug resistance and social and ethnic group.

Disseminated infection with Mycobacterium genavense: a challenge to physicians and mycobacteriologists

In the present study we compared the clinical presentations of patients with a clinical diagnosis of AIDS and disseminated Mycobacterium genavense infection (n = 12) with those of patients with AIDS and disseminated M. avium complex (MAC) infection (n = 24). Abdominal pain was seen more frequently in the group of patients infected with M. genavense than in patients infected with MAC (P = 0. 003). Analysis of microbiological data revealed that stool specimens from patients infected with M. genavense were more often smear positive than stool specimens from patients infected with MAC (P = 0. 00002). However, M. genavense could be cultured on solid media from only 15.4% of the stool specimens, whereas MAC could be cultured from 71.4% of the specimens. Bone marrow and liver biopsy specimens yielded growth of M. genavense within a reasonably short time, allowing species identification by DNA technology. Microbiological data clearly demonstrated the importance of acidic liquid medium for primary culture, the avoidance of pretreatment and the use of additives in culture, and the necessity for prolonged incubation if M. genavense is suspected. Susceptibility testing showed that M. genavense is sensitive to rifamycins, fluoroquinolones, and macrolides, whereas it is resistant to isoniazid. Susceptibility to ethambutol and clofazimine could not be evaluated. The mean survival times of patients in the two groups were similar.

Phase II study of oral platinum drug JM216 as first-line treatment in patients with small-cell lung cancer

PURPOSE

This multicenter phase II trial was performed to determine tumor efficacy and tolerance of the oral platinum drug JM216 in patients with small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Patients with SCLC limited disease unfit for intensive chemotherapy or those with extensive disease received JM216 120 mg/m(2)/d for 5 consecutive days every 3 weeks. Individual dose escalation to 140 mg/m(2)/d was allowed if toxicity was </= grade 2 according to the National Cancer Institute Common Toxicity Criteria. Tumor response was evaluated according to World Health Organization criteria.

RESULTS

Twenty-seven patients were assessable for toxicity and 26 for tumor response. Eighty-eight cycles were administered. Common Toxicity Criteria grade 3 and 4 hematologic toxicities were neutropenia in 15.9% and 3.7%, lymphocytopenia in 47.6% and 17.1%, and thrombocytopenia in 19.5% and 10.3% of cycles, respectively. One patient suffered from neutropenic fever. Nausea, vomiting, and diarrhea were the most common nonhematologic toxicities. Except for grade 4 diarrhea in one patient, no grade 4 nonhematologic toxicity was observed. No severe neurotoxicity or nephrotoxicity was observed. Tumor response rate was 10 of 26 (38%; 95% confidence interval, 19% to 58%), excluding five unconfirmed partial responses. No complete responses were observed. Median overall time to progression was 110 days (range, 5 to 624 days). Median overall survival time was 210 days (range, 5 to 624 days).

CONCLUSION

Oral JM216 is active in previously untreated patients with SCLC and shows mild toxicities.

[Medical training therapy in lumbar syndromes]

Chronic low back pain can be considered to be one of the most frequently treated and most costly diseases in modern industrial societies. Dysfunctions and imbalances of the spine-supporting muscles increase the risk of low back pain. Consequently preventive treatment and rehabilitation have to aim at preserving and restoring the full capacity of the spine-supporting muscles as well as training coordination and spine-friendly behaviour. In addition to various measures of pain therapy, physiotherapeutic treatment including neuro-physiotherapy, physical treatment (eg electrotherapy), balneotherapy and supportive behavioural training, medical rehabilitation therapy (MRT) ranks among the most effective ways of treating low back pain. MRT applies guidelines and methods of exercise methodology within medically indicated programmes of preventive treatment and rehabilitation. Various objectives of MRT are outlined with special regard to the stages of MRT treatment, emphasizing positive adaptation of the neuro-muscular system in the course of rehabilitation. Physicians are responsible for MRT diagnosis and control. Taking into account the base disorder and the progress of therapy physiotherapists and the physicians in charge determine MRT objectives and treatment strategies.

Prostate biopsy schemes: 3-D visualization-based evaluation

We have developed a prostate needle biopsy visualization system for the evaluation and optimization of biopsy schemes. Three-dimensional (3-D) prostate surface models have been reconstructed from the digitized whole-mount radical prostetactomy specimens with localized cancers. We have conducted evaluation of five major biopsy schemes with a total of 201 3-D prostate models. These are sextant, 10-pattern, 12-pattern, 14-pattern, and the 5-region schemes. The 10- and 12-pattern biopsy schemes had a 99.0% detection rate, while the rate of traditional sextant biopsy scheme was only 72.6%. The 5-region biopsy scheme had a 90.5% detection rate and the 14-pattern, which includes all the biopsies used in the above schemes, added only one additional positive case (99.5%). Our results suggest that biopsy schemes that use laterally placed biopsies based on the five region anatomical model are superior to the routinely used sextant biopsy scheme. Significant correlation is found between the tumor volume and the positive needle core volume for each of these five schemes. The 10-pattern scheme is the best in cancer detection among these five biopsy schemes.

[In vitro evaluation of potentially effective gemcitabine combination therapy for exocrine pancreatic carcinoma]

The aim of the present study was to define potentially synergistic gemcitabine drug combinations for the treatment of pancreatic adenocarcinoma by using a tumour-specific in vitro screening system. The anticancer drug screening system used for these experiments consisted of four different established human pancreatic adenocarcinoma cell lines (BxPc-3, Panc-1, ASPC-1, Ca-pan-1) and the Microculture Tetrazolium (MTT) Assay for quantification of cytotoxic drug effects. To define single agent activities, dose-response curves, IC 50 values, and in order to validate the test system, in a first step gemcitabine and several conventional anticancer drugs including 5-FU, cisplatin, epirubicin, and mitomycin C were tested at 10 different concentrations ranging from 0.001 to 100 micrograms/ml. The effectiveness of various gemcitabine combinations was subsequently determined by using clinically relevant in vitro drug concentrations, and was rated as synergistic, additive or subadditive according to the criteria of Aapro. Overall, a heterogeneous chemosensitivity pattern was noted within the four tested cell lines. In agreement with the known chemotherapeutic refractoriness of pancreatic cancer, major cytotoxic effects were only seen with use of rather high drug concentrations. Investigation of various drug exposure times revealed a superior antiproliferative activity of gemcitabine and the other compounds in case of prolonged incubation. During subsequent drug combination experiments, gemcitabine + cisplatin and gemcitabine + epirubicin resulted in synergistic activity in 2/4 cell lines each. As opposed to the poor activity of single agents, a > 50% growth inhibition (in vitro response) was noted in 3 and 2 cell lines, respectively. Experimental data obtained with this pancreatic cancer specific in vitro screening system suggest that dose escalation or prolonged administration of gemcitabine, as well as the combination of this drug with cisplatin or epirubicin might result in improved therapeutic results. Encouraging preliminary results obtained in phase II studies seem to support the potential clinical relevance of the described disease-oriented screening system.

Principles underlying the organization of movement initiation from quiet stance

The purpose of this study was to determine common principles underlying the programming of movement initiation from quiet stance. Subjects were asked to initiate gait, step over a ruler, or to step over a 10 cm high obstacle at a self-paced speed and as fast as possible. The independent variables were initiation condition (gait initiation, stepping over a ruler or obstacle) and initiation speed (self-paced and as fast as possible). The dependent measures for the stance limb only were the latency between postural soleus (S(1)) EMG inhibition and tibialis anterior (TA) EMG onset, the duration of both TA and soleus (S(2)) activity following TA, duration and slope, impulse, and peak forces of the anterior-posterior (Fx) ground reaction force. Selected timing events were also monitored. Analysis of variance was used to determine main and interaction effects. The following results were obtained. (1) The interval from the inhibition of S(1) postural activity to the onset of TA remained invariant between all conditions. (2) The duration of TA increased and S(2) decreased with an increase in speed of initiation. There was no difference in TA and S(2) duration between the initiation conditions. (3) Time to heel-off remained invariant for all conditions. (4) Prior to heel-off all force variables increased with initiation speed but were similar between initiation conditions. After heel-off force variables were different between speeds and conditions being greater for fast speed and stepping over the obstacle. Two conclusions may be drawn from this study. First, the results indicate that gait initiation consists of two, highly coordinated motor programs. Heel-off of the stance limb is the division between these two programs. Second, our findings also suggest that gait initiation and stepping are governed by the same motor programs.

Simultaneous myocardial revascularization and aortic valve replacement: stentless versus stented bioprostheses

Implantation of stentless aortic valve prostheses is more time-consuming than implantation of conventional stented bioprostheses. Simultaneous myocardial revascularization can result in a considerably prolonged operation time. We reviewed our patients with regard to surgical aspects in the specific patient cohorts. From April 1996 to April 1999, 303 patients were operated for aortic valve disease with or without concomitant coronary artery revascularization. Mean age was 75 years, ranging between 36 and 90 years. Using the Medtronic Freestyle valve, the following techniques of implantation were used: subcoronary technique, 163 patients, 61.5%; root inclusion technique, 7 patients, 3.5%; total root replacement, 30 patients, 15%. Total hospital mortality rate was 5.6%, reflecting age and concomitant disease of these patients. For isolated aortic valve replacement, the mortality rate was 4.7% and 6.7% for combined procedures. Coronary artery patients who are not suitable for stentless valve implantation owing to extensive aortic root calcification have a higher perioperative mortality rate. Compared with the isolated valve replacement and despite more extensive surgery and prolonged operative time, simultaneous myocardial revascularization in patients with stentless prostheses implantation can be performed without an increased risk.