The thrombospondin-like chains of cartilage oligomeric matrix protein are assembled by a five-stranded alpha-helical bundle between residues 20 and 83

The N-terminal fragment of rat cartilage oligomeric matrix protein (COMP), comprising residues 20-83, was over-expressed in E. coli and purified under non-denaturing conditions. The fragment forms pentamers similar to the assembly domain of the native protein. Its five chains can be covalently linked in vitro by oxidation of cysteines 68 and 71. The fragment adopts a predominantly alpha-helical structure as judged by circular dichroism spectroscopy. On the basis of these findings we propose the model of a five-stranded alpha-helical bundle for the assembly domain of COMP. The studied sequence is conserved in thrombospondins 3 and 4 thus raising the possibility that these proteins are also pentamers.

Structural investigation of Cetrorelix, a new potent and long-acting LH-RH antagonist

The new decapeptide SB-75 (INN: Cetrorelix) has been characterized as a potent antagonist of luteinizing-hormone releasing hormone (LH-RH). Such derivatives are of great medicinal interest owing to their potential application in areas such as hormone-dependent tumors, uterine fibroids, and in diseases and conditions which result from inappropriate hormone levels or which can be treated by suppression of estrogens. SB-75 is the subject of intensive ongoing clinical evaluation and is an accepted standard for the design of new LH-RH antagonists. We characterized SB-75 by means of modern MS and NMR techniques to demonstrate the significance of both sequencing methods on a complicated unnatural decapeptide. Our structural elucidations with nuclear Overhauser (NOE) experiments revealed clear evidence for a highly flexible molecule with no single predominant conformation even in sodium dodecyl sulfate (SDS) mimicking a cellular membrane.

Asymmetric interictal glucose hypometabolism and cognitive performance in epileptic patients

OBJECTIVE

To relate hemispheric metabolic asymmetries to cognitive performance in patients with unilateral mesial temporal lobe epilepsy.

DESIGN

Asymmetrical cerebral glucose metabolisms on interictal fludeoxyglucose F 18 positron emission tomograms (FDG-PET) were correlated with cognitive measures. Analyses included partial correlations that controlled for the correlation between metabolic asymmetries of the lateral temporal lobe and other brain regions and the correlation of IQ scores with affected cognitive scores.

SETTING

A university epilepsy surgery center.

PATIENTS

Subjects included 13 patients who had intractable complex partial seizures originating from a mesial temporal lobe.

INTERVENTION

Patients underwent FDG-PET scanning as part of their diagnostic work-up. Asymmetry indexes for cerebral metabolic rates were determined for whole hemisphere, lateral temporal lobe, mesial temporal lobe, frontal lobe, thalamus, and parietal lobe.

MAIN OUTCOME MEASURES

The following cognitive domains were assessed: psychometric intelligence, mental control/attention, language, and verbal and nonverbal memory. Neuropsychological measures were obtained within 14 days of FDG-PET scanning.

RESULTS

Relative reductions in glucose metabolism of the left hemisphere and left lateral temporal lobe correlated with a lower verbal IQ score and a lower score on a verbal memory task, recall of logical prose. Relative reduction in metabolism of the left side of the thalamus also correlated with lower scores for recall of logical prose.

CONCLUSION

Relative hypometabolism of the left hemisphere correlates with lower cognitive performance. Hypometabolism of the left lateral temporal lobe and thalamus independently correlates with the verbal memory difficulties seen in this epileptic patient population.

Depression in complex partial seizures. Electroencephalography and cerebral metabolic correlates

OBJECTIVE

We sought to determine whether the frequency of depressive disorders among patients with complex partial seizures is associated with the laterality of ictal onset or the laterality of interictal cerebral hypometabolism.

DESIGN

Fifty-three patients with medically intractable complex partial seizures were assessed for history of interictal depressive disorders meeting strict Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R), criteria with use of a modification of the Structured Clinical Interview for DSM-III-R. All subjects underwent video-electroencephalographic telemetry and fludeoxyglucose F18 positron emission tomographic scanning. The main outcome measure was the frequency of a history of major depressive episodes (MDEs) in subjects with left-sided vs right-sided ictal onset and in subjects with left-sided vs right-sided temporal lobe hypometabolism.

RESULTS

Thirty-three subjects (62%) had a history of interictal depressive disorders, 16 (30%) of whom met criteria for one or more MDEs. More of those with left-sided ictal onset had a history of depression. Thirty-six subjects had definite unilateral temporal lobe hypometabolism demonstrated by positron emission tomographic scanning. More of those with left temporal lobe hypometabolism had a history of MDEs, and the combination of left temporal lobe hypometabolism and high-degree hypometabolism was strongly associated with a history of MDEs. Furthermore, among those with right temporal lobe hypometabolism, more of those with high-degree hypometabolism had a history of MDEs.

CONCLUSION

Laterality of ictal onset and degree of interictal temporal lobe hypometabolism may be interdependent factors that contribute to the risk of depressive disorder in patients with complex partial seizures.

Chronic pretreatment with naloxone modifies benzodiazepine receptor binding in amygdaloid kindled rats

Male Sprague-Dawley rats received either naloxone (75 micrograms/h) or saline (0.5 microliter/h) s.c. for 14 days delivered with osmotic minipumps. Two days after termination of either treatment, daily amygdala kindling stimulation was applied until the animals experienced stage V kindled seizures. Benzodiazepine (BDZ) binding sites were labeled with [3H]flunitrazepam (2 nM), and changes in specific brain areas were determined by in vitro quantitative autoradiography. Twenty-four hours after the last electrical stimulation, the saline pretreated fully kindled rats showed enhanced BDZ receptor binding in dentate gyrus, and decreased binding in cingulate cortex ipsilateral to the stimulation compared to saline controls. Twenty-eight days after the last stage V kindled seizure, the significant alterations were no longer evident. In agreement with a previous study, we found that naloxone pretreated amygdala kindled rats showed stage V kindled seizures followed by intervals of 3-5 days in which the same electrical stimulation failed to induce any behavioral and EEG alterations. In comparison with the saline pretreated kindled and saline control groups, the naloxone pretreated kindled rats had significantly higher BDZ binding in different cortical areas, amygdala complex, hippocampus, substantia nigra and periaqueductal gray, 24 h after the last electrical stimulation. The present study indicates that previous chronic exposure to naloxone increases BDZ receptor binding in kindled rats, and suggests that this effect may be associated with the enhanced seizure suppression observed in these animals.

Characterization of native laminin from bovine kidney and comparison with other laminin variants

A comprehensive characterization of laminin isoforms requires access to native preparations of laminins of a defined subunit composition. For this purpose an optimized isolation procedure was developed and shown to be broadly applicable to normal mammalian tissues. The protocol does in addition yield side fractions highly enriched in collagens XII and XIV. The major laminin purified from bovine kidney is indistinguishable from mouse Engelbreth-Holm-Swarm (EHS) tumor laminin in electron microscopy, but contains an A chain that migrates in a position intermediate to the Ae and the Am chains on SDS/PAGE. Antisera raised against mouse EHS-tumor laminin crossreact with B chains, but not with the A chain, of kidney laminin. Further, this A chain is not recognized by antisera raised against the Am chain. Laminins from heart and kidney both contain a significant subpopulation with a 190-kDa polypeptide identified as the B1s chain. The Am-containing laminins from heart and placenta differ morphologically from the Ae-containing EHS laminin in having one short arm that does not have the characteristic globule-rod-globule appearance. Further, the Am-containing laminins show a significantly higher thermal stability of the coiled-coil alpha-helical region in the long arm than does Ae-containing EHS laminin, indicating that certain combinations of laminin chains interact more strongly than others.

NGF increases [Ca2+]i in regenerating mature oligodendroglial cells

The effect of NGF on [Ca2+]i of mature regenerating oligodendroglial cells was investigated by measuring fluo-3 fluorescence. NGF caused transient increases in [Ca2+]i, which could be inhibited by anti-NGF antibody. The rise in [CA2+]i was in part due to influx of extracellular Ca2+ since it was markedly attenuated in Ca2+-free solution. It also depended on release of Ca2+ from intracellular stores as tested by prior depletion with cyclopiazonic acid. These results support a role for Ca2+ in the effects of NGF on oligodendroglial cells.

Efficacy study of THINKable in the attention and memory retraining of traumatically head-injured patients

The efficacy of computer-assisted attention and memory retraining was evaluated with 15 severely head-injured patients. Training with selected exercises tailored to the individual's needs were provided from the THINKable program for up to 20 hours in both the attention and memory remediation modules. The experimental design evaluated outcome by juxtaposing multiple baseline procedures with a pre- and post-group comparison. Significant results were documented on the computerized tasks, psychometric measures and on patient and observer ratings of everyday behaviours of attention and memory.

Direct detection of the intracellular formation of carboxyphosphamides using nuclear magnetic resonance spectroscopy

31P nuclear magnetic resonance (NMR) spectroscopy was used in conjunction with cell perfusion techniques to monitor the intracellular chemistry of the cyclophosphamide (CP, CAS 6055-19-2) metabolites 4-hydroxy-cyclophosphamide (4-HO-CP) and aldophosphamide (AP) in U937 human histiocytic (CP-sensitive) and K562 human erythroleukemia (CP-resistant) cells. Similar experiments were carried out using the ifosfamide (IF, CAS3778-73-2) metabolites 4-hydroxyifosfamide (4-HO-IF) and aldoifosfamide (AIF). The hydroxy and aldehydic metabolites were generated by the triphenylphosphine reduction of 4-hydroperoxycyclophosphamide (4-HO2-CP) or 4-hydroperoxyifosfamide (4-HO2-IF) or by a spontaneous elimination/addition reaction involving water and 4-thiocyclophosphamide analogs 4-(2-hydroxyethyl) thiocyclophosphamide (4-ESCP) or mafosfamide. Cell death resulting from 4-HO-CP/AP perfusions was mimicked by perfusion with acrolein or an acrolein producing but non-alkylating, dechloro-CP analog. Acrolein toxicity was minimized by the presence of 2-mercaptoethanol or mesna (sodium 2-mercaptoethanesulfonate) in perfusion solutions as well as by fractional dose drug perfusions (sequential 2.5-3.0 h perfusions separated by cell washes with drug-free medium). The intracellular half-life for phosphoramide mustard (PM) at an intracellular pH value of 7.1 +/- 0.1 and an ambient probe temperature of 23 +/- 1 degree C in U937 cells was 2.1 h [k = (5.4 +/- 0.3) x 10(-3) min-1] and in K562 cells was 3.1 h [k = (3.7 +/- 0.4) x 10(-3) min-1]. Similar half-lives (2-4 h) were determined for intracellular isophosphoramide mustard (IPM). Fractional dose perfusion of U937 or K562 cells with 1.5 mmol/l 4-HO-CP/AP (generated from 4-HO2-CP) and 0.3 mmol/l mesna allowed for the observation of intracellular carboxyphosphamide (CBP); CBP was formed in higher concentrations in the CP-resistant K562 cells. Similar results were obtained using 4-ESCP and mafosfamide as sources of 4-HO-CP/AP. Identification of CBP was based on chemical shift, chemical stability, and membrane permeability studies of synthetic CBP. Concentrations of carboxyifosfamide (CBIF) formed in K562 cells were also greater than that in U937 cells.

Clinical evaluation of interictal fluorine-18-fluorodeoxyglucose PET in partial epilepsy

Interictal [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) is useful in presurgical evaluation of medically refractory partial epilepsies. Limited replicability of image interpretation may restrict this application. We investigated interpretation replicability in 241 18F-FDG studies performed with three different tomographs in partial epilepsy patients. Two investigators independently interpreted the studies with a standardized evaluation protocol and without knowledge of the subjects. Replicability of these unbiased interpretations in detection of regional hypometabolism was best for studies performed with the highest performance tomograph. Interictal 18F-FDG studies performed with this tomograph revealed regional hypometabolism in 62% of patients who had normal cerebral magnetic resonance imaging (MRI). Replicability of interpretations in detecting regional hypometabolism was adequate for clinical application of interictal 18F-FDG studies performed with any of the tomographs.

Cloning and characterization of the RNA polymerase alpha-subunit operon of Chlamydia trachomatis

We have cloned the chlamydial operon that encodes the initiation factor IF1, the ribosomal proteins L36, S13, and S11, and the alpha subunit of RNA polymerase. The genes for S11 and alpha are closely linked in Escherichia coli, Bacillus subtilis, and plant chloroplast genomes, and this arrangement is conserved in Chlamydia spp. The S11 ribosomal protein gene potentially encodes a protein of 125 amino acids with 41 to 42% identity over its entire length to its E. coli and B. subtilis homologs; the gene encoding the alpha subunit specifies a protein of 322 amino acids with 25 to 30% identity over its entire length to its E. coli and B. subtilis homologs. In a T7-based expression system in E. coli, the chlamydial alpha gene directed the synthesis of a 36-kDa protein. Mapping of the chlamydial mRNA transcript by RNase protection studies and by a combination of reverse transcription and the polymerase chain reaction demonstrates that IF1, L36, S13, S11, and alpha are transcribed as a polycistronic transcript.

Interictal heart rate patterns in partial seizure disorders

Epileptogenic mesial temporal damage may alter interictal autonomic patterning. Analysis of heart rate variability in 19 patients with complex partial seizures revealed cases of persistent, high-amplitude, 4 to 9 per minute fluctuations in heart rate during alert waking. This pattern was most pronounced in poor candidates for anterior temporal lobe resection (2/19). The 4 to 9 per minute heart-rate variability pattern may emerge following diffuse, extratemporal, or bilateral mesial temporal damage, which interferes with descending forebrain influences on cardiovascular regulation.

Surgical treatment of partial epilepsy arising from the insular cortex. Report of two cases

Despite its documented connections with many limbic structures, the role of the insula in the etiology of partial seizures is poorly understood. Two patients are described in whom lesions of the insula were associated with intractable partial seizures. In the first patient, the seizures involved visceral sensory hallucinations followed by motor automatism. Seizures in the second patient began with somatic sensory hallucinations and then produced visceral motor effects. Both patients were found to have low-grade astrocytomas of the insula. In both instances, resection of the lesion and adjacent insular cortex resulted in a cure of the seizures. These cases are placed within the context of the existing literature on the subject.

[New central analgesic-acting triaminopyridines]

New Triaminopyridines with a Central Analgesic Activity 2-Amino-3-((prop-1-en-3-yl)oxycarbonylamino)-6-(4-fluorobenzyla mino) pyridine hydrochloride (D-19050) is a centrally and peripherally acting analgesic with rapid onset, long duration of action and a good therapeutic range. D-19050 can be obtained in a 5-step-synthesis starting from 2,6-dichloropyridine.

Interictal metabolic anatomy of mesial temporal lobe epilepsy

OBJECTIVE--To examine patterns of temporal and extratemporal regional interictal glucose hypometabolism in individual patients with unilateral mesial temporal lobe epilepsy (TLE). Previous reports disagree on which extratemporal areas can be hypometabolic in TLE. DESIGN--Case series of patients with TLE who underwent interictal fludeoxyglucose F 18 positron emission tomography, compared quantitatively with normal positron emission tomography. SETTING--Patients referred for surgical treatment of medically refractory complex partial seizures. PATIENTS AND OTHER PARTICIPANTS--Ten normal volunteers; 27 patients with TLE selected to exclude seizures of bilateral temporal or extratemporal onset. RESULTS--Regional hypometabolism occurred in 25 patients. Hypometabolic regions were ipsilateral to seizure onset and included lateral temporal (in 78% of patients), mesial temporal (70%), thalamic (63%), basal ganglial (41%), frontal (30%), parietal (26%), and occipital (4%). Specific patterns of temporal and extratemporal hypometabolism varied considerably across the TLE group. CONCLUSIONS--Any of the previously reported anatomic areas of hypometabolism can occur in individual patients with TLE. The prevalence of thalamic hypometabolism suggests a pathophysiologic role for the thalamus in initiation or propagation of temporal lobe seizures or in the interictal cognitive dysfunction of TLE.

Further validation of the Revised Inquiry Mode Questionnaire

The 1988 revised version of the Inquiry Mode Questionnaire by Harrison and Bramson was administered to 216 nursing students in the post-RN baccalaureate programs at two universities. The first purpose was to validate further this measure of relative preference in forced-choice format for five main ways of thinking, Synthesist, Idealist, Pragmatist, Analyst, and Realist. Significant differences among thinking styles on analysis of variance with repeated measures supported the tests's predictive validity. There were negative intercorrelations (≥ – 0.40) between opposing styles such as Synthesist/Pragmatist, Synthesist/Realist, Pragmatist/Analyst, and Idealist/Realist. Ninety percent (81 of 90 items) were significant in discriminating among the styles of thinking. The second purpose to ascertain whether nurses show a particular thinking-style preference was confirmed. Nurses in this study preferred the Idealist (37.5%), Realist (36.1%), and Analyst (31%) styles of thinking.

Benzodiazepine receptor binding following chronic treatment with naloxone, morphine and met-enkephalin in normal rats

The effects of chronic administration of naloxone, morphine and met-enkephalin on benzodiazepine (BDZ) receptor binding in rat brain were determined 2 and 50 days after treatments were accomplished. Two days after naloxone treatment (75 micrograms/h s.c. for 14 days), enhanced BDZ receptor binding was observed in cingulate, frontal, piriform, entorhinal and sensorimotor cortices; amygdala complex, hippocampus, substantia nigra and central gray. Two days after morphine treatment (20 mg/kg i.p. daily for 6 days), increased BDZ receptor binding was detected in cingulate, frontal, piriform, entorhinal and sensorimotor cortices; amygdala complex, hippocampus and substantia nigra. Two days after met-enkephalin treatment (10 micrograms/h i.c.v. for 6 days) enhanced BDZ receptor binding was shown only in sensorimotor cortex. No significant changes were observed 50 days after the treatments were completed. These data indicate an important interaction between GABAergic and opioid peptide systems.

Ionic interactions in the coiled-coil domain of laminin determine the specificity of chain assembly

Laminins are a family of large (800 to 900 kDa) multidomain glycoproteins specifically found in basement membranes. They consist of one heavy A chain and two light chains B1 and B2, and several tissue-specific laminin isoforms exist. Chain assembly is mediated through the formation of a rod-like triple-stranded alpha-helical coiled-coil domain about 75 nm long. The interacting edges of the chains are mostly formed by hydrophobic residues in positions a and d of an (abcdefg)n heptad sequence repeat and by a distinct pattern of charged residues in positions e and g. Here, we have analyzed the sequences of known laminin chains in an effort to relate them to interaction potential. Initially, those sequences localized in the long arm were arranged in an optimum heptad-repeating scheme. The interacting edges between chains were then analyzed for interchain hydrophobic and ionic interactions. The short heptad blocks were allowed to shift axially with respect to each other to maximize the number of interactions. The number of hydrophobic interactions was very high and similar for all chain combinations, but especially so for homodimers. As these were not observed experimentally, it seems that hydrophobic interactions probably represent only a prerequisite for coiled-coil formation. The number of ionic interactions, however, directly resembles the interaction potential observed in in vitro experiments. In particular, the number of interchain ionic interactions is high for parallel heterodimer configurations of A and B chains, but low for homodimer arrangements. When the laminin isoform chains, rat s-laminin (B1s) and human merosin (Am), are included in the analysis, they show rather low numbers of mutual interactions but high ionic interaction potentials between them and distinct mouse laminin chains are predicted. For mouse laminin the analysis was extended to a full three-stranded coiled-coil structure. The highest number of interchain ionic interactions occurs for an anti-clockwise chain arrangement of A-->B1-->B2 when viewed from the N terminus. None of the laminin chains appears to be designed for the formation of homodimers, although such conformations are frequently found in other alpha-fibrous proteins.

Clinical neurophysiology, neuroimaging, and the surgical treatment of epilepsy

Improved neurodiagnostic tools for examining cerebral structure and function have greatly enhanced the safety and efficacy of surgical treatment for epilepsy, and markedly increased the number of candidates for these surgical interventions. The application of new developments in clinical neurophysiology, as well as recent advances in neuroimaging, for surgical therapy of medically refractory seizures are reviewed. Improvements in surgical results are documented and future directions are discussed.