Theta coupling in the human electroencephalogram during a working memory task

The role of coupling between prefrontal and temporo-parietal brain areas within the theta frequency range of the human electroencephalogram was explored in a working memory task. During encoding of visual information higher theta amplitudes were observed in the right compared to the left hemisphere. Retrieval of visuospatial and verbal information elicited a more bilateral activation pattern. These effects were accompanied by theta coupling between dorsolateral prefrontal and right posterior temporal electrode sites during encoding. During retrieval prefrontal and bilateral temporo-parietal brain areas were coupled. These results support the idea of working memory functions being dependent on distributed prefrontal-temporal networks.     

The Bioperl toolkit: Perl modules for the life sciences

The Bioperl project is an international open-source collaboration of biologists, bioinformaticians, and computer scientists that has evolved over the past 7 yr into the most comprehensive library of Perl modules available for managing and manipulating life-science information. Bioperl provides an easy-to-use, stable, and consistent programming interface for bioinformatics application programmers. The Bioperl modules have been successfully and repeatedly used to reduce otherwise complex tasks to only a few lines of code. The Bioperl object model has been proven to be flexible enough to support enterprise-level applications such as EnsEMBL, while maintaining an easy learning curve for novice Perl programmers. Bioperl is capable of executing analyses and processing results from programs such as BLAST, ClustalW, or the EMBOSS suite. Interoperation with modules written in Python and Java is supported through the evolving BioCORBA bridge. Bioperl provides access to data stores such as GenBank and SwissProt via a flexible series of sequence input/output modules, and to the emerging common sequence data storage format of the Open Bioinformatics Database Access project. This study describes the overall architecture of the toolkit, the problem domains that it addresses, and gives specific examples of how the toolkit can be used to solve common life-sciences problems. We conclude with a discussion of how the open-source nature of the project has contributed to the development effort.     

Experimental double infection of Biomphalaria glabrata snails with Angiostrongylus cantonensis and Schistosoma mansoni

Summary Two groups of Biomphalaria glabrata snails primarily infected with Angiostrongylus cantonensis were secondarily exposed to infection with Schistosoma mansoni. To investigate any antagonistic effect of a first infection on a superimposed one and to compare to singly and non-infected snails, a series of experiments was undertaken in which snails were individually exposed, variously, to 1,000 and 2,000 first-stage larvae of A. cantonensis and then to 5 and 10 miracidia of S. mansoni 1 day and 3 weeks later.Snails became infected with S. mansoni in both groups of snails with double infections and shed cercariae after the same incubation period as in the singly infected groups. The number of snails shedding cercariae simultaneously was similar in single and double infection groups during the first two weeks of shedding, after which this number decreased somewhat in doubly infected groups. Snails with double infection showed higher cumulative mortality rates than in snail groups with single infection with either A. cantonensis or S. mansoni. Therefore, initial infection of B. glabrata with A. cantonensis produced no inhibitory or retarding effect on subsequent infection of snails with S. mansoni.

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Zusammenfassung Zwei Gruppen der Süßwasserschnecke Biomphalaria glabrata, die zuvor mit 1000 bzw. 2000 ersten Larven von Angiostrongylus cantonensis pro Schnecke infiziert worden waren, wurden zur Feststellung eines eventuellen antagonistischen Effekts zwischen beiden Parasiten, einen Tag und drei Wochen später mit 5 bzw. 10 Miracidien von Schistosoma mansoni infiziert. Nicht infizierte und mit jeweils nur einer der beiden Parasitenarten infizierte Schnecken dienten als Kontrolle.In beiden doppelt infizierten Gruppen ging die S. mansoni-Infektion sehr gut an, und die Ausscheidung von Cercarien begann nach der gleichen Entwicklungszeit wie bei den nur mit S. mansoni infizierten Kontrollgruppen. Die Anzahl Cercarien ausscheidender Schnecken war in den beiden ersten Wochen bei den jeweils einzeln und doppelt infizierten Gruppen sehr ähnlich, während sie sich in der Folgezeit in den doppelt infizierten Gruppen rasch verminderte. In Gruppen mit Doppelinfektion zeigte sich eine höhere Mortalität als bei den jeweils nur mit A. cantonensis oder S. mansoni infizierten Schnecken. Eine Beeinflussung der Entwicklung von S. mansoni durch die vorausgegangene Nematodeninfektion konnte nicht nachgewiesen werden.

     

Polymere imidazolcarbonsäuren, 2. Über das schwermetallionenbindungsvermögen von chelatharzen mit 4,5-sicarboxyimidazolyl-gruppen

The swelling behaviour, the time-dependence of the uptake of Cu²⁺-ions, and the pH-dependence of the uptake of Cu²⁺-, Ni²⁺-, Cd²⁺-, Zn²⁺- and Mg²⁺-ions of crosslinked poly[1-(4,5-dicarboxy-1-imidiazolyl)ethylene] ( 1 ) and poly{1-[p-(4,5-dicarboxy-2-imidazolyl)phenyl]ethylene} ( 2 ) were investigated. Both resins have a high selectivity for heavy metal ions. For resins 1 the uptake of heavy metal ions in the presence of an excess of EDTA was studied. Furthermore the possibility to remove Hg²⁺-ions from aqueous alkalichloride solutions by resin 1 was investigated.     

Über poly[1-N-(4-isothiocyanatophenyl)carbamoyloxy-methyläthylen-co-1-hydroxymethyläthylen]e als träger zur immobilisierung von papain

Poly[1-N-(4-isothiocyanatophenyl)carbamoyloxymethylethylene-co-1-hydroxymethylethylene]s ( 5a – c ) were obtained by reaction of poly(allyl alcohol) ( 2 ) with 4-isothiocyanatophenyl isocyanate ( 3 ). In some cases 1,4-phenylenediisocyanate ( 4 ) was used as crosslinking agent. These reactive carriers were found to be suitable to immobilize enzymes by covalent bonds. The binding abilities of these polymers 5a – e for butylamine, 3,4-dichloroaniline, peptone (from lactalbumin), and papain were investigated. The enzymatic activity, the pH-optimum, the apparent Michaelis-constant K_M(app), and the activity dependance on temperature were determined for the immobilized papain.     

Amphotere ionenaustauscher, 5

Amphoteric ion exchangers with uniform structure were obtained by copolymerization of aziridinyl monomers followed by alkaline saponification of the ester groups of the polymers. The following compounds were copolymerized: Diethyl 2,4-di(1-aziridinyl)glutarate ( 1 ) with either diethyl (1-aziridinyl)succinate ( 4 ), diethyl (1-aziridinyl)fumarate ( 5 ) or dimethyl (1-aziridinylmethyl)succinate ( 6 ); diethyl ester of 3,3′-(1,4-phenylene) and 3,3′-(1,3-phenylene)di[3-(1-aziridinyl)propionic acid] ( 2a ) and ( 2b ), respectively, with either methyl (1-aziridinyl) acetate ( 7 ) or methyl (1-aziridinyl)propionate ( 8 ); dimethyl 3,6-di(1-aziridinyl)cyclohexane-1,2-dicarboxylate ( 3 ) with dimethyl 6-(1-aziridinyl)cyclo-2-hexene-1,2-dicarboxylate ( 9 ). Further the dioctylester of 3,3′-(1,4-phenylene)di[3-(1-aziridinyl)propionic acid] ( 10 ) was homopolymerized. The properties of the amphoteric resins were investigated. In particular the binding ability for Cu^2⊕, Ni^2⊕, Zn^2⊕, and Mg^2⊕ ions and the swelling ability were studied as function of the pH of the solution. The uptake of CU²⁺ ions was determined as a function of time. An average capacity for Cu²⁺ ions of 2,5 to 3,75 mmol/g of dry resin was found at pH 5,5–6.     

Lymphokine-activated killer (LAK) cells can be focused at sites of tumor growth by products of macrophage activation

Successful adoptive cancer immunotherapy presumably depends on the accumulation of tumoricidal leukocytes at the sites of tumor growth. Large numbers of lymphokine-activated killer (LAK) cells can be generated in vitro by growth in high concentrations of interleukin-2 (IL-2), but relatively few arrive at the tumor site after intravenous injection. We hypothesize that the delivery of LAK cells to tumor sites may be augmented by previously demonstrated lymphocyte-recruiting factors, including activated macrophage products such as interleukin-1 (IL-1) and tumor necrosis factor. 111Indium-labeled LAK cells were injected intravenously into syngeneic mice bearing the macrophage activator endotoxin (LPS) in one hind footpad, and saline solution was injected into the contralateral footpad. Significantly more activity was recovered from the LPS-bearing footpad at all times during a 96-hour period. Recombinant IL-1 also attracted more LAK cells after injection into tumor-free hind footpads. Furthermore, LAK cells preferentially homed to hind footpads that were bearing 3-day established sarcomas after intralesional injections of LPS, IL-1, or tumor necrosis factor when compared with contralateral tumor-bearing footpads injected with saline solution alone. In preliminary experiments, mice with hind-footpad tumors appeared to survive longer after combined systemic IL-2 and LAK therapy if intralesional LPS was administered. These studies demonstrate that macrophage activation factors that have been shown capable of attracting circulating normal lymphocytes can also effectively attract LAK cells from the circulation. By the stimulation of macrophages at the sites of tumor growth, more LAK cells can be attracted. It is hoped that by "focusing" the migration of LAK cells to tumors, LAK cells and IL-2 would effect tumor regression more efficiently and with less toxicity.     

Polymyxin B,a selective inhibitor of protein kinase C,diminishes the release of noradrenaline and the enhancement of release caused by phorbol 12,13-dibutyrate

Summary Slices of the rabbit hippocampus were labelled with ³H-noradrenaline, superfused continuously with a modified Krebs-Henseleit medium containing the uptake inhibitor cocaine and stimulated electrically (2 ms, 3 Hz, 24 mA, 5 V/cm). Phorbol 12,13-dibutyrate (PDB), a potent activator of protein kinase C (PKC), strongly enhanced the electrically-evoked overflow of tritium. In contrast, polymyxin B, a relatively selective inhibitor of PKC, diminished the evoked tritium overflow in a time-and concentration-dependent manner. The enhancement of the evoked overflow of tritium caused by PDB was strongly reduced in the presence of polymyxin B (100 mol/l). These results suggest 1. that PKC may be involved in the physiological mechanism of action-potential-induced noradrenaline release from noradrenergic nerve terminals and 2. that the PDB-induced enhancement of noradrenaline release may be due to a direct activation of PKC.Abbreviations PKC protein kinase C - PDB phorbol 12,13-dibutyrate - TPA 12-O-tetradecanoyl 13-acetate     

Traumatic aneurysms of the descending thoracic aorta

From July 1979 to December 1985 we observed 51 patients with traumatic lesions of the descending thoracic aorta. Twenty-nine had acute ruptures, mostly accompanied by multiple injuries, and 27 had to be operated upon immediately. Twenty-two patients (19 males, 3 females) had chronic traumatic aneurysms of the descending thoracic aorta (more than six weeks after trauma). Mean age at the time of trauma was 24 years. Mean age at time of surgery was 36.5 years. Twelve patients were symptomatic. All were treated surgically. At surgery, complete aortic disruption was found in 15 patients and partial rupture in seven. We did not use aortic shunting of any kind, only aortic cross-clamping. Hypertension was controlled by intravenous drug infusion. The ruptured aortic segment was replaced in all cases by prosthetic Dacron graft. There were no operative deaths. One patient (age 77) died 11 weeks after surgery from multiple organ failure. One case of postoperative paraplegia was observed. This patient recovered almost completely from his neurological deficit.     

AUR Memorial Award. Two computer models for selection of optimal magnetic resonance imaging (MRI) pulse sequence timing

Two computer modeling techniques have been developed that aid in the selection of optimal magnetic resonance imaging (MRI) pulse sequences and timing intervals for specific clinical situations. The "parameter sensitivity" technique provides a means of selecting three separate MRI scans which are individually sensitive to changes in each of the three NMR tissue parameters N, T1, and T2. The "contrast" technique allows selection of a single optimal MRI sequence using the expected changes in all three tissue parameters simultaneously. Excellent correlation is demonstrated between the models and images obtained in a normal volunteer and in a patient with multiple sclerosis. The two methods compliment each other; the parameter sensitivity method is most useful in situations where subtle changes in tissue parameters are expected, whereas the contrast method is suited to circumstances where large differences in tissue parameters are anticipated and the magnitude and direction of these changes are known.