Differentiating the sedative, psychomotor and amnesic effects of benzodiazepines: a study with midazolam and the benzodiazepine antagonist, flumazenil

Sixteen healthy volunteers were administered midazolam followed by placebo or the benzodiazepine antagonist, flumazenil, in a double-blind, cross-over study. Flumazenil reversed midazolam-induced sedation on the subjective, psychophysiological and motor indices used. In contrast, there was little evidence of any reversal of amnesic effects, which were assessed using both direct (explicit) and indirect (implicit) measures of memory. Results are discussed in terms of dissociating the sedative and amnesic effects of benzodiazepines.

Intracerebral clysis in a rat glioma model

OBJECTIVE

Intracerebral clysis (ICC) is a new term we use to describe convection-enhanced microinfusion into the brain. This study establishes baseline parameters for preclinical, in vivo, drug investigations using ICC in a rat glioma model.

METHODS

Intracranial pressure was measured, with an intraparenchymal fiber-optic catheter, in male Fischer rats 10, 15, 20, and 25 days after implantation of C6 glioma cells in the right frontal lobe (n = 80) and in control rats without tumor (n = 20), before and during ICC. A 25% albumin solution (100 microl) was infused through an intratumoral catheter at 0.5, 1.0, 2.0, 3.0, and 4.0 microl/min. Infusate distribution was assessed by infusion of fluorescein isothiocyanate-dextran (Mr 20,000), using the aforementioned parameters (n = 36). Brains were sectioned and photographed under ultraviolet light, and distribution was calculated by computer analysis (NIH Image for Macintosh). Safe effective drug distribution was demonstrated by measuring tumor sizes and apoptosis in animals treated with N,N'-bis(2-chloroethyl)-N-nitrosourea via ICC, compared with untreated controls. Magnetic resonance imaging noninvasively confirmed tumor growth before treatment.

RESULTS

Intracranial pressure increased with tumor progression, from 5.5 mm Hg at baseline to 12.95 mm Hg on Day 25 after tumor cell implantation. Intracranial pressure during ICC ranged from 5 to 21 mm Hg and was correlated with increasing infusion volumes and increasing rates of infusion. No toxicity was observed, except at the higher ends of the tumor size and volume ranges. Fluorescein isothiocyanate-dextran distribution was greater with larger infusion volumes (30 microl versus 10 microl, n = 8, P < 0.05). No significant differences in distribution were observed when different infusion rates were compared while the volume was kept constant. At tolerated flow rates, the volumes of distribution were sufficient to promote adequate drug delivery to tumors. N,N'-Bis(2-chloroethyl)-N-nitrosourea treatment resulted in significant decreases in tumor size, compared with untreated controls.

CONCLUSION

The C6 glioma model can be easily modified to study aspects of interstitial delivery via ICC and the application of ICC to the screening of potential antitumor agents for safety and efficacy.

Frequent type 2 neurofibromatosis gene transcript mutations in sporadic intramedullary spinal cord ependymomas

OBJECTIVE

To further investigate the role of Type 2 neurofibromatosis (NF2) gene transcript mutations in the sporadically occurring counterparts of NF2-associated tumors.

METHODS

Reverse transcription-polymerase chain reaction followed by agarose gel electrophoresis, single strand conformation polymorphism analysis, and automated deoxyribonucleic acid sequence analysis were used to screen for mutations in the NF2 gene transcript in seven unrelated patients with sporadic intramedullary spinal cord ependymomas.

RESULTS

Five of seven intramedullary spinal cord ependymomas harbored detectable mutations. All of these mutations occurred in the region of the transcript that is homologous to known cytoskeletal proteins and resulted in significant truncation of the predicted protein product.

CONCLUSION

Mutations of the NF2 transcript occur in the majority of sporadic intramedullary spinal cord ependymomas. These mutations are frequent in a region of the transcript that is homologous to a family of cytoskeletal proteins, and they probably render the protein product inactive. These results add to the body of knowledge concerning the role of the NF2 gene transcript in tumorigenesis.

Atlantoaxial degenerative articular cysts

Cysts associated with spinal joints are not a common cause of neurological symptoms. The authors report a series of five patients with cysts of the atlantodental articulation and review five additional cases from the literature. The patients ranged from 60 to 85 years of age and included three men and seven women. No patient had evidence of rheumatoid arthritis or previous trauma. The cysts caused ventral cervicomedullary compression, did not enhance on magnetic resonance imaging, and were not associated with widening of the anterior atlantodental interval or osseous degeneration of the dens. All patients improved postsurgery. Fusion was required if a transoral procedure was performed. Patients undergoing posterior decompressions were clinically and radiographically stable after operation.

Intranuclear Ca2+ transients during neurite regeneration of an adult mammalian neuron

Depolarization-induced increases in cytoplasmic and intranuclear Ca2+ were visualized in adult mammalian dorsal root ganglion (DRG) neurons during different stages of neurite extension by using confocal laser scanning microscopy and the long-wavelength Ca2+ indicator dye fluo 3-AM (acetoxymethyl ester of fluo 3). In neurons beginning to extend neurites, depolarization led to pronounced increases in nuclear and nucleolar Ca2+ levels severalfold greater than corresponding increases in the cytoplasm. The nucleolar Ca2+ signal often exceeded that of the nucleus, indicating regional heterogeneity of the nucleus. The subcellular calcium transients were dependent on extracellular Ca2+ and the level of depolarization, indicating the importance of transmembrane Ca2+ fluxes in triggering the nuclear events. After neurite extension, the nuclear Ca2+ signals were attenuated and never exceeded cytoplasmic levels. These results indicate that activity-dependent modulation of intranuclear Ca2+ levels is greater in DRG neurons during early neurite extension. Given the importance of Ca2+ in gene expression, the results may be relevant to Ca(2+)-dependent nuclear events responsible for axonal regeneration.

A voltage- and time-dependent rectification in rat dorsal spinal root axons

1. Rat dorsal spinal roots were studied by the use of whole-nerve sucrose gap and intra-axonal recording techniques. A prominent time-dependent conductance increase as evidenced by a relaxation or "sag" in membrane potential toward resting potential was elicited in dorsal spinal roots by constant hyperpolarizing current pulses. The relaxation, or sag, indicative of inward rectification, reached a maximal level and then decayed during the current pulse. 2. The time-dependent sag elicited by hyperpolarization was reduced when Na+ or K+ was removed from the normal bath solution but was abolished with the removal of both Na+ and K+. Tetrodotoxin (TTX), tetraethylammonium (TEA), and 4-aminopyridine (4-AP) did not affect the depolarization sag, suggesting that conventional voltage-dependent sodium and potassium channels do not underlie the inward rectification. 3. Cs+ in low concentrations completely abolished the inward rectification, whereas Ba2+ induced a partial block. 4. Current-voltage curves indicate that the magnitude of the depolarizing sag increases monotonically with increasing hyperpolarization. The time required to reach peak hyperpolarization, maximal sag potential, and the time between peak hyperpolarization and sag membrane potentials decreases with increasing levels of hyperpolarization. 5. The inward rectification is refractory to further stimulation during its decay phase, as revealed by paired-pulse protocols. This decay in inward rectification is both time and voltage dependent and is observed on a single axon level by the use of intra-axonal recording techniques as well as from whole-root recordings in the sucrose gap. 6. It is concluded that rat dorsal root fibers display a prominent time-dependent conductance increase in response to hyperpolarization that depends on both Na+ and K+ permeability and is blocked by Cs+. This rectification displays a decay phase that has not been previously described for similar conductances. It is argued that the Na+ component of this conductance is primarily responsible for stabilizing membrane potential near resting potential during periods of hyperpolarization.

L-phenylisopropyladenosine (L-PIA) diminishes halothane anesthetic requirements and decreases noradrenergic neurotransmission in rats

The effect of L-phenylisopropyladenosine (L-PIA), the A1 adenosine agonist, on the depth of anesthesia was investigated in halothane-anesthetized rats. L-PIA treatment reduced the minimum anesthetic concentration (MAC) of halothane that prevented 50% of animals from moving in response to a painful stimulus by 49%. MAC experiments performed with L-PIA given in conjunction with A1 adenosine receptor antagonists which either permeate the blood-brain barrier (8-phenyltheophylline [8-PT] or do not (8-sulphophenyltheophylline [8-So-PT]) indicate that central mechanisms are involved. Noradrenergic neurotransmission was diminished following L-PIA administration in halothane-anesthetized rats in all brain regions. These data suggest that acute L-PIA treatment decreases central noradrenergic neurotransmission and may represent the mechanism for the decrease in halothane dose to achieve an anesthetic endpoint anesthetic response to halothane.

The differential effects of flumazenil on the psychomotor and amnesic actions of midazolam

Forty-four patients given midazolam prior to day-care urological surgery had the benzodiazepine antagonist, flumazenil, or placebo administered postoperatively. Flumazenil reversed the psychomotor impairments induced by midazolam but not its amnesic effects. There was no evidence of resedation for up to 6 h following the use of flumazenil.

The uptake and metabolism of uridine by the slime mould Physarum polycephalum

1. Uridine is taken up by microplasmodia of Physarum polycephalum via a saturatable transport system with an apparent Km of 29 muM. An intracellular concentration significantly higher than that in the growth medium is attained, suggesting that the uptake is an active process. Both deoxyribonucleosides and ribonucleosides are competitive inhibitors of the uptake of uridine. 2. In contrast, the rate of entry of uridine into surface plasmodia is a linear function of the concentration of the nucleoside in the growth medium, and the uptake is not inhibited by other nucleosides. 3. As well as serving as a source of pyrimidine nucleotides for the synthesis of nucleic acids, uridine is also catabolised by P. polycephalum. Uracil accumulates in the growth medium and there is also significant conversion of C-2 of the pyrimidine ring to CO2. The proportion of uridine subject to catabolism in surface plasmodia is less than that observed for microplasmodia.

Regulation of protein synthesis in the plasmodial phase of Physarum polycephalum

1. The rate of protein synthesis changes very little during the first 2-3 h (S phase) of the nuclear division cycle in plasmodia of Physarum polycephalum and then increases continuously during G2 phase, so that by the end of the cycle the rate has doubled relative to that in S phase. Protein synthesis appears to continue during mitosis. 2. Fractionation of extracts of plasmodia, labeled with [3H]lysine for 1 h, by two-dimensional electrophoresis indicated that most if not all proteins are synthesised throughout the nuclear division cycle. However, two metabolically stable polypeptides, the synthesis of which occurs predominantly in Gs phase, were detected. 3. Using a double-labelling procedure, the differential rates of synthesis of 30 relatively abundant polypeptides were measured in relation to the nuclear division cycle. As a group, their differential rates of synthesis increase during the cycle so that their actual rates of synthesis increase 4-6-fold. This implies that their synthesis is regulated over and above any simple change due to a doubling in the number of genes during S phase.

1500 cases of renal and ureteric calculi treated in an integrated stone centre

Fifteen hundred consecutive cases of renal and ureteric calculi were treated in an integrated stone centre; 1464 of these were treated by extracorporeal shockwave lithotripsy, percutaneous nephrolithotomy, ureterorenoscopy and ureteroscopic lasertripsy. Only 36 (2.4%) required open surgery.

Design of a continuous passive and active motion device for hand rehabilitation

This paper presents the design of a novel, portable device for hand rehabilitation. The device provides for CPM (continuous passive motion) and CAM (continuous active motion) hand rehabilitation for patients recovering from damage such as flexor tendon repair and strokes. The device is capable of flexing/extending the MCP (metacarpophalangeal) and PIP (proximal interphalangeal) joints through a range of motion of 0 degrees to 90 degrees for both the joints independently. In this way, typical hand rehabilitation motions such as intrinsic plus, intrinsic minus, and a fist can be achieved without the need of any splints or attachments. The CPM mode is broken into two subgroups. The first mode is the use of preset waypoints for the device to cycle through. The second mode involves motion from a starting position to a final position, but senses the torque from the user during the cycle. Therefore the user can control the ROM by resisting when they are at the end of the desired motion. During the CPM modes the device utilizes a minimum jerk trajectory model under PD control, moving smoothly and accurately between preselected positions. CAM is the final mode where the device will actively resist the movement of the user. The user moves from a start to end position while the device produces a torque to resist the motion. This active resistance motion is a unique ability designed to mimic the benefits of a human therapist. Another unique feature of the device is its ability to independently act on both the MCP and PIP joints. The feedback sensing built into the device makes it capable of offering a wide and flexible range of rehabilitation programs for the hand.

Progesterone: a novel adjunct to intravesical chemotherapy

OBJECTIVE

To investigate the effect of progesterone on multidrug-resistant urothelial cell lines, as the failure of intravesical chemotherapeutic drugs is often caused by multidrug resistance (MDR), mediated by the drug efflux pump P-glycoprotein (PGP), the function of which can be down-regulated by various compounds including steroid hormones.

MATERIALS AND METHODS

Two urothelial cell lines (RT112S and MGH-U1S) and their MDR sublines (RT112R, to cisplatin; and MGH-U1R, a cell line expressing PGP) were used to assess the cytotoxic effects of progesterone, epirubicin and their combination. Cytotoxicity was assessed using a tetrazolium-based assay and in situ confocal microscopy.

RESULTS

Cell lines sensitive to epirubicin (MGH-U1S, RT112S and RT112R) required a much lower dose of epirubicin to kill half the cells than did the MDR cell line. Progesterone was intrinsically cytotoxic to all cell lines with little difference among them. Combined therapy had no cumulative effect on epirubicin-sensitive cell lines, but reversed MDR in the MGHU1R cell line, both assessed by confocal microscopy and by the tetrazolium assay.

CONCLUSIONS

Progesterone can reverse MDR in urothelial cells in vitro. This, combined with its effects on cell differentiation and apoptosis, together with its safety and tolerability compared to other MDR agents, suggests it may be a valuable adjunct to intravesical chemotherapy.

Seminal tissue factor revisited

Studies of seminal tissue factor (TF) are few and mostly based on small numbers. Due to the reported lack of factor (F) X in semen, it has been suggested that TF may not have a role in seminal coagulum formation. However, recent identification of a number of haemostatic factors in semen justifies a re-evaluation of its occurrence. Semen specimens were collected from sub-fertile (n = 19), normally fertile (n = 33), semen donors (n = 30) and vasectomized subjects (n = 62), some fractionated into sperm, a prostasome-rich fraction and seminal plasma. Functional and antigenic TF levels were measured and related to conventional fertility parameters. Semen contains high concentration of functional and antigenic TF. Most TF was found in seminal plasma prepared by low-speed centrifugation. When further fractionated by ultracentrifugation much of this may reside in the pellet (prostasomal fraction). It was also detectable on sperm. TF antigen levels were higher in vasectomized subjects than sub-fertile, normally fertile, donor (p = 0.02) and a 'pooled normal semen parameters' (PNSP) stratification (derived from a combination of measurements) (p = 0.06). The sub-fertile group showed a wider variation than normal, donor or the PNSP subjects. Seminal TF antigen levels correlated significantly with sperm agglutination (p = 0.03) and abnormal sperm morphology (p = 0.04). Subjects with anti-sperm antibodies also showed high TF antigen levels. In conclusion, semen contains functional and antigenic TF at high concentrations. A full complement of clotting factors probably exists in semen, so some pro-coagulant role for TF should not be excluded. Decreased seminal TF levels appear to be associated with seminal parameters that are known to favour male fertility.

Transfer RNA and ribosomal RNA are synthesized from the same pyrimidine nucleotide pool

We have tested the hypothesis [Wiegers, Kramer, Klapproth & Hilz (1976) Eur. J. Biochem. 64. 535-540] that the synthesis of rRNA in the nucleolus may have a partially independent supply of nucleoside triphosphates that is not completely suppressed when cells are supplied with exogenous nucleosides. For the slime mould, Physarum polycephalum, and Chinese hamster ovary cells in culture, the specific activities (3H/32P) of UMP and CMP in tRNA, which is synthesised in the nucleoplasm, and rRNA were compared after continuous labelling with [3H]uridine and [32P]phosphate. No differences were found, suggesting that transcription throughout the nucleus draws on a common supply of pyrimidine triphosphates that is uniformly labelled from exogenous [3H]uridine. As a control of the radioactive labelling schedule, a similar experiment was carried out with the prokaryote, Escherichia coli, and identical results were obtained.

Anguidine: a broad phase II study of the Southeastern Cancer Study Group

Anguidine, a phase II agent, was used to treat 276 patients with solid tumors. The overall evaluability rate was 68%. Hematologic toxicity was substantial but not prohibitive. There were no complete responses, two partial responses, and 12 stabilizations.