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47 records · Page 3Linked to original sources
PubMed1984

An improved drug infusion pump for injecting nanoliter volumes subcortically in awake rats.

A new drug infusion pump capable of injecting nanoliter volumes of drug solution into the brains of awake rats has been constructed which incorporates a new "turntable" commutator and a compact tubing compressor mechanism requiring no gears. Injector cannulas inserted into guide cannulas permanently mounted in the rat's skull are connected to the drug pump by spring-protected, PE 10 tubing. Drug solutions are delivered when the pump rollers compress the drug-filled PE 10 tubing. An additional animal-activated switch and motorized mechanism rotates the drug pump in response to the animal's movements so that the PE 10 drug reservoir is not twisted. Testing the drug pump's performance in vivo with injections of 14C-nicotine into the caudate nucleus shows that drug delivery is both reliable and reproducible.

Animals↗
PubMed2003

Involvement of precerebellar nuclei in multiple system atrophy.

In this semiquantitative study based on 26 post-mortem cases, we describe the involvement of precerebellar nuclei in multiple system atrophy (MSA), a progressive degenerative disorder of the human central nervous system characterized by abnormal, argyrophilic and alpha-synuclein immunopositive intracellular inclusions within selectively vulnerable oligodendrocytes and nerve cells. The Campbell-Switzer silver-pyridine technique with alpha-synuclein immunoreactions using 100-microm thick sections is recommended over more conventional methods, thereby permitting visualization of the pertinent lesions in greater detail and facilitating post-mortem diagnosis of MSA specimens. Affected oligodendrocytes occur in specific fibre tracts and grey matters, with most pathology being observed in projections from the precerebellar nuclei to the cerebellum (ponto-cerebellar, olivo-cerebellar, reticulo-cerebellar tracts) and in descending/ascending fibre tracts of the motor system (cortico-pontine, cortico-bulbar, cortico-spinal, spino-reticular, spino-olivary, spino-cerebellar tracts). Three types of abnormal intraneuronal aggregations occur: (i) a loosely woven network within the cell nucleus; (ii) a latticework accumulating in peripheral portions of the cell body; and (iii) irregularly outlined patches of compact, intensely argyrophilic material usually located within deposits of lipofuscin granules. Counter-staining for the presence of extraneuronal lipofuscin can aid neuropathologists in the recognition of lost existent neurones in MSA. Neurones with inclusion bodies occur in the inferior olivary nuclear complex, lateral reticular nucleus, external cuneate nucleus, conterminal nucleus, interfascicular nucleus, nucleus of Roller, dorsal paramedian reticular nucleus, subventricular nucleus, arcuate nucleus, pontobulbar body and pontine grey. The lateral reticular nucleus and accessory nuclei of the inferior olive sustain the most damage and reveal prominent neuronal loss, followed by the pontobulbar body and arcuate nucleus. The uniformly bilateral damage and, in some cases, even obliteration of the nuclei studied, supply additional evidence for the pathoanatomical substrata of the cerebellar dysfunction that reportedly emerges in the clinical course of MSA.

Aged↗
PubMed2001

Biomechanical comparison of two racing wheelchair propulsion techniques.

PURPOSE: The purpose was to compare the conventional (CVT) and para-backhand (PBT) techniques used for racing wheelchair propulsion. Selected 3-D kinematic characteristics of the upper body and the electromyographic (EMG) signals of selected muscles during racing wheelchair propulsion over a roller system were examined. METHODS: Eight CVT and seven PBT elite performers served as the subjects. Each subject performed maximum effort pushing for 30 s at a load that simulated overground pushing. Two S-VHS camcorders (60 Hz) were used to obtain 3-D kinematic parameters and muscle activity was monitored using surface electrodes. RESULTS: The CVT was found to have significant shorter push time, smaller relative push time, and greater relative recovery time than the PBT. The CVT is a more compact stroke (smaller joint range of motion) and the PBT has a faster overall movement speed. Significant differences in arm positions were found between the two techniques at the instants of hand contact and hand release, and the upper arm was more internally rotated at these two instants in the CVT when compared with the PBT. The EMG data showed that large variations in muscle activation patterns existed in each technique group. In general, the flexor carpi radialis and triceps brachii were most active in the push phase. The upper trapezius and postero-middle deltoids were most active in the ascending recovery phase, whereas the extensor carpi radialis, biceps brachii, antero-middle deltoids, and pectoralis major were most active during the descending recovery phase. CONCLUSIONS: The greater push time and push angle associated with the PBT suggest that the PBT may be more suitable for endurance athletes who are less explosive in their pushing strokes. The greater time and angle allow PBT users the opportunity to transmit more force to the wheel.

Adult↗
PubMed2002

Flaking corn: processing mechanics, quality standards, and impacts on energy availability and performance of feedlot cattle.

Based on performance of feedlot cattle, steam flaking increases the value of corn by 18%, considerably more than is suggested by tabular values. Tabular values underestimate the energy availability of flaked corn by failing to account for digestibility of the nonstarch OM that is increased by flaking by the same magnitude (10%) as starch. Correcting for improvement in digestibility of nonstarch OM increases the NEg value of steam-flaked corn to 1.70 Mcal/kg, a value very close to values calculated from cattle performance trials. Digestibility of starch from corn grain is limited by the protein matrix that encapsulates starch granules, and by the compact nature of the starch itself. Disruption of the protein matrix (by shear forces on hot grain during flaking) is the first limiting step toward optimizing starch digestion. Five critical production factors influence the quality of steam-flaked corn: steam chest temperature, steaming time, roll corrugation, roll gap, and roll tension. For optimal shear, it is important that rolls be hot and that kernels be hot when flaked. Steam chests should be designed to allow a steaming time of at least 30 min at maximum roller mill capacity producing a flake of 0.31 kg/L (24 lb/bushel). As little as 5% moisture uptake during steaming appears adequate. The rate of flaking and distribution of kernels across the rolls also are critical. Quality standards for steam-flaked corn include measurements of flake thickness, flake density, starch solubility, and enzyme reactivity. Flake density, the most common quality standard, closely associated with starch solubility (r2 = 0.87) and enzyme reactivity (r2 = 0.79), still explains only 63% of the variability in percentage fecal starch and 52% of the variability in starch digestibility. Direct determination of fecal starch can explain 91% of the variability in starch digestion. The NEg value of corn can be predicted from fecal starch: NEg= 1.78 - 0.0184FS. Starch digestion is a Kappa Curve function of hot flake density, reaching a maximum at a flake density of approximately 0.31 kg/L. Flaking to a density of less than 0.31 kg/L, though increasing starch solubility, may reduce DMI, increase variability of weight gain among animals within a pen, and predispose cattle to acidosis and bloat without increasing starch digestion. We recommend that the steam-flaking process be optimized on the basis of fecal starch analysis.

Animal Feed↗
PubMed1995

Gas exchange efficiency of a membrane oxygenator with use of a vibrating flow pump.

We have developed a newly designed blood pump, named the vibrating flow pump (VFP), which can generate high frequency oscillated flow. The driving frequency is 10-50 Hz, and flow volume is linearly controlled electric power (current and voltage). The VFP was applied as the pump for extracorporeal circulation (ECC) in acute animal experiments. The gas exchange efficiency of the membrane oxygenator with the VFP and a roller pump (RP) was evaluated. Under general anesthesia with halothane, 7 adult goats underwent ECC; an inflow cannula was inserted into the right atrium, an outflow cannula was sutured to the descending thoratic aorta, and total ECC was performed with a flow of about 80 ml/min/kg. The ECC system with the VFP showed excellent gas exchange efficiency compared with that of the RP. The hemodynamics of ECC using the VFP were easily maintained within normal limits. These results suggest that the VFP is very useful as a pump for ECC; thus, a compact-sized ECC system may be achieved.

Animals↗
PubMed2004

Pulsed quantum-cascade laser-based sensor for trace-gas detection of carbonyl sulfide.

Simultaneous exhaled carbonyl sulfide (OCS) and carbon dioxide concentration measurements in human breath are demonstrated with a compact pulsed quantum-cascade laser-based gas sensor. We achieved a noise-equivalent sensitivity (1sigma) of 1.2 parts per billion by measuring a well-isolated OCS P(11) absorption line in the v3 band at 2057.6 cm(-1) using an astigmatic Herriott cell of 36-m optical path length and 0.4-s acquisition time.

Journal Article↗
PubMed2003

Carbonyl sulfide detection with a thermoelectrically cooled midinfrared quantum cascade laser.

A compact absorption spectrometer with a midinfrared tunable quantum cascade laser operating at 4.86 microm (2054 cm(-1)) is used to measure lower concentrations of carbonyl sulfide (COS) in air. A detection sensitivity of approximately 30 parts in 10(9) of COS and the selectivity of two stable isotopes, 12C(16)O32S and 12C(16)O34S, are demonstrated. Specifically, the feasibility of detecting COS in expired human breath as a potential noninvasive medical diagnostic tool is investigated.

Journal Article↗
PubMed2004

The compact Erlangen Active Simulator for Interventional Endoscopy: a prospective comparison in structured team-training courses on "endoscopic hemostasis" for doctors and nurses to the "Endo-Trainer" model.

BACKGROUND: In 1997 Hochberger and Neumann presented the "Erlangen Biosimulation Model" (commercialized as the "Erlangen Endo-Trainer") at various national and international meetings. The new compactEASIE is a simplified version of the original "Biosimulation Model" (Endo-Trainer) and is specially designed for easy handling. CompactEASIE is reduced in its features, focusing exclusively on flexible endoscopy training. The acceptance of training in endoscopic hemostasis is accepted by workshop participants, as evaluated by a questionnaire on both models. METHODS: Eleven structured courses on endoscopic hemostasis for doctors and nurses organized by the same endoscopists from 3/1998 to 5/1999 were evaluated using one of both models. The questionnaires were filled in by 207/291 trainees (71%). The Endo-Trainer was used in 4 (n = 103) and the compactEASIE in 7 courses (n = 104). Both simulators were equipped with identical types of specially prepared pig-organ packages consisting of esophagus, stomach and duodenum, including artificial sewn-in vessels, polyps and varices. Blood perfusion was done with a roller pump connected to the sewn-in vessels and blood surrogate. All workshops were identical concerning the course structure: a 30-min theoretical introduction on ulcer bleeding was followed by 2 h of practical training in injection techniques and hemoclip application. The second part of variceal therapy consisted of a 30-min theoretical introduction prior to 2 h of practical training on sclerotherapy, band ligation and cyanoacrylate application. Finally, a questionnaire on the trainees' pre-experience and their rating of the different workshop sections was handed out to each participant. RESULTS: Previous endoscopic experience was comparable in both groups. The training in both simulators was highly accepted by the trainees (compactEASIE 95% excellent and good versus EASIE (Endo-Trainer) 97%) and did not show any significant difference (P = 0.493). Even in the assessment of the single techniques, no statistical difference was observed. Furthermore, the assessments of the closeness to reality and the endoscopic environment in both simulators were identical. CONCLUSIONS: Both simulators (Endo-Trainer, compactEASIE) are excellent educational tools for interventional endoscopy with a high level of acceptance. The easy-to-handle, "lightweight" compactEASIE is a significant, progress tool for the future.

Clinical Competence↗
PubMed2005

Binding affinity difference induced by the stereochemistry of the sulfoxide bridge of the cyclic peptide inhibitors of Grb2-SH2 domain: NMR studies for the structural origin.

The SAR study on a phage library-derived non-phosphorylated cyclic peptide ligand of Grb2-SH2 domain indicates that the configuration of the cyclization linkage is crucial for assuming the active binding conformation. When the thioether linkage was oxidized to the two chiral sulfoxides, the R-configured sulfoxide-cyclized peptide displayed 10-30 times more potency than the corresponding S-configured one in binding affinity to the Grb2-SH2 domain. In this paper, the solution structures of such a pair of sulfoxide-bridged cyclic peptide diastereoisomers, i.e., cyclo[CH(2)CO-Gla(1)-L-Y-E-N-V-G-NPG-Y-(R/S)C(O)(10)]-amide, were determined by NMR and molecular dynamics simulation. Results indicate that the consensus sequence of Y(3)-E(4)-N(5)-V(6) in both diastereoisomers adopt a beta-turn conformation; however, the R-configured peptide forms an extended structure with a circular backbone conformation, while the S-configured isomer forms a compact structure with key residues buried inside the molecule. The average root-mean-square deviations were found to be 0.756 and 0.804 A, respectively. It is apparent that the chiral S-->O group played a key role in the solution structures of the sulfoxide-bridged cyclic peptides. The R-sulfoxide group forms an intramolecular hydrogen bond with the C-terminal amide, conferring a more rigid conformation with all residues protruding outside except for Leu2, in which the Gla1 and Tyr3 share an overlapping function as previous SAR studies proposed. Additionally, the extended structure endows a more hydrophilic binding surface of the R-configured peptide to facilitate its capture by its targeted protein. In comparison, the S-configured sulfoxide was embedded inside the ligand peptide leading to a compact structure, in which the essential residues of Gla1, Tyr3, and Asn5 form multiple intramolecular hydrogen bonds resulting in an unfavorable conformational change and a substantial loss of the interaction with the protein. The solution structures disclosed by our NMR and molecular dynamics simulation studies provide a molecular basis for understanding how the chirality of the cyclization linkage remarkably discriminates in terms of the binding affinity, thus advancing the rational design of potent non-phosphorylated inhibitors of Grb2-SH2 domain as antitumor agents.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Mid-infrared quantum cascade laser based off-axis integrated cavity output spectroscopy for biogenic nitric oxide detection.

Tunable-laser absorption spectroscopy in the mid-IR spectral region is a sensitive analytical technique for trace-gas quantification. The detection of nitric oxide (NO) in exhaled breath is of particular interest in the diagnosis of lower-airway inflammation associated with a number of lung diseases and illnesses. A gas analyzer based on a continuous-wave mid-IR quantum cascade laser operating at approximately 5.2 microm and on off-axis integrated cavity output spectroscopy (ICOS) has been developed to measure NO concentrations in human breath. A compact sample cell, 5.3 cm in length and with a volume of < 80 cm3, that is suitable for on-line and off-line measurements during a single breath cycle, has been designed and tested. A noise-equivalent (signal-to-noise ratio of 1) sensitivity of 10 parts in 10(9) by volume (ppbv) of NO was achieved. The combination of ICOS with wavelength modulation resulted in a 2-ppbv noise-equivalent sensitivity. The total data acquisition and averaging time was 15 s in both cases. The feasibility of detecting NO in expired human breath as a potential noninvasive medical diagnostic tool is discussed.

Exhalation↗
PubMed1994

Organotypic slice culture of the rat suprachiasmatic nucleus: sustenance of cellular architecture and circadian rhythm.

The suprachiasmatic nucleus of the mammalian brain is thought to be the anatomical locus of circadian rhythms. To examine the functional organization of the suprachiasmatic nucleus in vitro with intact intercellular connections for a prolonged period, we have established an organotypic slice culture system using a roller-tube technique. Brain slices (400 microns in thickness) containing the bilateral suprachiasmatic nuclei, were obtained from newborn rats at four to seven days old and were maintained in vitro for more than three weeks. During this three-week period, the slices flattened to one to three cell layers and two tightly packed neuronal cell-masses (neuronal zones), with diameters of about 1 mm were formed, which were surrounded by a peripheral glial cell-dispersed zone. In the neuronal cell zones, peptides and their messenger RNAs were found cytochemically with characteristic patterns similar to the suprachiasmatic nucleus in the brain. In situ hybridization and immunocytochemistry showed that vasoactive intestinal peptide messenger RNA expressing and vasoactive intestinal peptide-immunoreactive neurons were detected predominantly in the ventrolateral part of the neuronal zones in the suprachiasmatic nucleus slice culture. Vasopressin messenger RNA-expressing and vasopressin-immunoreactive cells were localized in the dorsomedial neuronal zones near the ependymal cell zone. The distribution of cell bodies and fibers containing these neuropeptides and their messenger RNAs in the neuronal zones of suprachiasmatic nucleus organotypic slice culture were similar to that of the suprachiasmatic nucleus in vivo. This suggests that the suprachiasmatic nucleus in these organotypic slice cultures retains the biological characteristics of these cells in vivo as the cells did develop, form compact neuronal masses and did establish connections. To examine the possibility that suprachiasmatic nucleus neurons in slice cultures show a persistent rhythmic activity, we also measured the amount of vasopressin released into the culture medium. Sampling at 4-h intervals combined with enzyme immunoassay revealed that vasopressin concentration in the medium embracing suprachiasmatic nucleus slice cultures fluctuated with a period of approximately 24 h. The present findings suggest that the intranuclear neuronal networks of the suprachiasmatic nucleus are maintained in vitro for a long duration and that organotypic cultures of the suprachiasmatic nucleus produce and release bioactive substances in an oscillating manner. The suprachiasmatic nucleus in slice cultures may be useful for future analysis of circadian rhythms in vitro.

Animals↗