Feasibility of joystick guided colonoscopy

The flexible endoscope is increasingly used to perform minimal invasive interventions. A novel add-on platform allows single-person control of both endoscope and instrument at the site of intervention. The setup changes the current routine of handling the endoscope. This study aims to determine if the platform allows effective and efficient manipulation to position the endoscope at potential intervention sites throughout the bowel. Five experts in flexible endoscopy first performed three colonoscopies on a computer simulator using the conventional angulation wheels. Next they trained with the joystick interface to achieve their personal level of intubation time with low pain score. 14 PhD students (novices) without hands-on experience performed the same colonoscopy case using either the conventional angulation wheels or joystick interface. Both novice groups trained to gain the average expert level. The cecal intubation time, pain score and visualization performance (% of bowel wall) were recorded. All experts reached their personal intubation time in 6 ± 6 sessions. Three experts completed their learning curve with low pain score in 8 ± 6 sessions. The novices required 11 ± 6 sessions using conventional angulation wheels, and 12 ± 6 sessions using the joystick interface. There was no difference in the visualization performance between the novice and between the expert groups. This study shows that the add-on platform enables endoscope manipulation required to perform colonoscopy. Experts need only a relatively short training period. Novices are as effective and as efficient in endoscope manipulation when comparing the add-on platform with conventional endoscope contro

A hydraulically driven colonoscope

BACKGROUND: Conventional colonoscopy requires a high degree of operator skill and is often painful for the patient. We present a preliminary feasibility study of an alternative approach where a self-propelled colonoscope is hydraulically driven through the colon. METHODS: A hydraulic colonoscope which could be controlled manually or automatically was developed and assessed in a test bed modelled on the anatomy of the human colon. A conventional colonoscope was used by an experienced colonoscopist in the same test bed for comparison. Pressures and forces on the colon were measured during the test. RESULTS: The hydraulic colonoscope was able to successfully advance through the test bed in a comparable time to the conventional colonoscope. The hydraulic colonoscope reduces measured loads on artificial mesenteries, but increases intraluminal pressure compared to the colonoscope. Both manual and automatically controlled modes were able to successfully advance the hydraulic colonoscope through the colon. However, the automatic controller mode required lower pressures than manual control, but took longer to reach the caecum. CONCLUSIONS: The hydraulic colonoscope appears to be a viable device for further development as forces and pressures observed during use are comparable to those used in current clinical practice

Guiding principles for the development and application of solid-phase phosphorus adsorbents for freshwater ecosystems

While a diverse array of phosphorus (P)-adsorbent materials is currently available for application to freshwater aquatic systems, selection of the most appropriate P-adsorbents remains problematic. In particular, there has to be a close correspondence between attributes of the P-adsorbent, its field performance, and the management goals for treatment. These management goals may vary from a rapid reduction in dissolved P to address seasonal enrichments from internal loading, targeting external fluxes due to anthropogenic sources, or long term inactivation of internal P inventories contained within bottom sediments. It also remains a challenge to develop new methods and materials that are ecologically benign and cost-effective. We draw on evidence in the literature and the authors’ personal experiences in the field, to summarise the attributes of a range of P-adsorbent materials. We offer 'guiding principles' to support practical use of existing materials and outline key development needs for new materials

Delayed hemolytic transfusion reaction due to anti-Jk a

rezime Background: Kidd antibodies are very heterogeneous and difficult to detect. They have been frequently implicated in delayed hemolytic transfusion reactions (DHTRs). Case report: A 64year old female (6 pregnancies, 2 deliveries, 4 abortions) with none red cell (RBC) transfusions in the history was admitted to hospital due to pneumonia and severe anemia. On admittance hemoglobin (Hb) level was 63g/L and hematocrit (Ht) 0,21L/L. The blood sample of the patient was sent to laboratory for serologic testing since RBC transfusions were required. Patient appeared to beO Rh(D)+ with negative both direct antiglobulin (DAT) and routine antibody screen (ID-DiaCell I+II+III-P). Three units of packed RBCs with negative crossmatch (tube method) were prepared. Patient received two units on Day 2 and one more on Day3 without any discomfort. Hematological values after the third unit were: Hb 116g/L and Ht 0,37L/L. On Day 6 she started to feel week, tired, with nausea and mild jaundice. Her Hb and Ht had dropped to 99g/L and 0,33L/L respectively, with tendency of dropping further (Day 7: Hb 83g/L,Ht 0,26L/L). Total serum bilirubin was 58,9 umol/L (normal range 20,5 umol/L) and direct fraction was 14,9 umol/L (normal range 7 umol/L). DTHR was suspected. Antibody identification performed by ID-DiaMed Gel Techique (GT) showed the presence of anti-Jk a with dosage phenomenon. All three previously transfused units were typed Jk a and the patient ’ s RBCs were Jk(a-b+). She received two units of Jk a negative packed RBCs and was well enough to be discharged on Day 14. Conclusion: It is important to monitor clinical effect of transfusion regularly and to provide good team work between specialists of transfusion medicine and related medical staff. The policy of transfusion practice is to keep pretransfusion sample for three weeks and to perform cross-match tests on the samples no older then 24h and 48h respectively

Acid unfolding of beta-2-microglobulin by repulsion of + charges

Peer reviewe

Hydrophobic core and surface charges of human beta-2-microglobulin probed by CD measurements

The roles of hydrophobic bonding and charge electrostatics in the stabilization of human beta-2-microglobulin have been probed by variations in solution conditions and monitored by circular dichroism in the near and far UV regions. Sodium perchlorate initially gives a decrease in intensity of the positive 234 nm peak in the near UV followed by a shift of this peak to negative ellipticity at high perchlorate concentration. These 234 nm changes indicate a new environment for a tyrosyl chromophore(s). A conformational rearrangement of the beta-sheet sandwich must occur since all six tyrosines of human beta-2-microglubulin are located in the two beta-sheets of this sandwich. A slight decrease in intensity for the 200 nm positive peak in the far UV indicates a less close packing of the beta-sheets at high perchlorate. In other experiments, enthalpy and entropy values have been calculated from thermal unfolding studies at 50 and 180 mm NaCl for pH values 6.0 and 8.0. Larger enthalpy values are obtained at higher NaCl concentration consistent with salt shielding of predominantly unfavorable charge interactions. These enthalpy differences are relatively large suggesting that charge electrostatics are energetically significant in stabilization of human beta-2-microglobulin.Peer reviewe

Mixed cobalt(III) complexes with S-tyrosine and 1,3-diaminopropane

Four out of six theoretically possible isomers of the (1,3-diaminopropane)bis(S-tyrosinato)cobalt(III) complex, having the cis(O) configuration, were isolated, and the trans(O) isomer was only defined in the eluate. The isomers were separated on an optically active Sephadex QAE column. Geometrical and absolute configurations of the isomers were determined by electronic absorption, circular dichroic and H-1 NMR spectra. The effect of the aromatic side group of the coordinated S-tyrosinato ligand on the stereoselective formation of the obtained isomers was examined

Discriminatory ability of calcaneal quantitative ultrasound in the assessment of bone status in patients with inflammatory bowel disease

A high incidence of bone disease in patients with inflammatory bowel disease (IBD) requires frequent monitoring of skeletal status and, for that reason, evaluation of radiation-free technology is an issue of interest. Our objective was to appraise the parameters of calcaneal quantitative ultrasound (QUS): broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness index (QUI), and establish their t-score values to investigate discriminatory ability of QUS in IBD patients with metabolic bone disease. The study included 126 patients (Crohn's disease [n = 94] and ulcerative colitis [n = 32]), and 228 age- and sex-matched healthy volunteers. Bone status was evaluated on the same day by calcaneal QUS and dual-energy x-ray absorptiometry (DXA) at spine (L1-L4) and total hip. All QUS measurements were lower in patients compared with healthy controls (BUA p < 0.001; SOS p < 0.001; QUI p < 0.001) and correlated significantly but inversely with disease duration (r = -0.3, p = 0.002). There was no difference with respect to type of disease (Crohn's disease or ulcerative colitis) or corticosteroid therapy. All three QUS t-scores were significantly lower in patients who had previously sustained fragile fractures (n = 28) than in those without fracture in their history (n = 98) (t-scores: BUA -2.0 vs. -1.3, p = 0.008; SOS -2.1 vs. -1.4, p = 0.02: QUI -2.3 vs. -1.5, p = 0.009). Axial DXA was not significantly different between the fracture and nonfracture patients (-1.7 vs. -1.2, p = 0.1), whereas total hip DXA showed a discriminatory power between the two (-1.6 vs. -0.7, p = 0.001). Patients with t-score < -1.0 scanned by DXA were classified as bone disease. The sensitivity of QUS to identify bone disease was 93% and specificity 63%. The sensitivity of QUS to detect osteopenia was 84% and 72% for osteoporosis. Alternatively, lower negative QUS t-score cutoff </= -1.8 identified 83% of osteoporosis at lumbar spine and 100% at total hip. All three QUS variables had t-scores less than -1.8 when osteoporosis was detected at both spine and hip. However, the subgroup of IBD patients with QUI t-score cutoff </= -1.8 still included 26% of individuals with normal bone status. Calcaneal QUS measurements may identify patients with IBD who are at a higher risk of fracture independently of DXA measurements. However, QUS showed poor agreement with bone status scanned by DXA and a low discriminatory power between osteopenia and osteoporosis

Influence of depyritization on NMR relaxation parameters of Aleksinac oil shale kerogen

Parallel proton and cross-polarization/magic-angle spinning (CP/MAS) nuclear magnetic resonance (NMR) relaxation measurements are reported on Aleksinac oil shale kerogen concentrate and pyrite-free kerogen concentrate. Possible relaxation mechanisms considered include proton-proton and C-13-proton interactions. The influence of depyritization on relaxation parameters is estimated. Depyritization prolongs the T-1H relaxation time constant by about five times. However, depyritization has no significant influence on relaxation in the rotating frame ( lt 5%). The probable explanation is that there is a certain motion of structural units with spectral density in the kHz region, which averages dipolar interactions between protons and pyrite. The repetition delay is found to be 150 ms for kerogen concentrate and 1-2 s for depyritized kerogen concentrate. The favourable value of contact time is identical for both samples, i.e., 1 ms. At the same time there are no significant changes observed in the CP/ MAS spectra of Aleksinac oil shale kerogen due to depyritization treatment, except for a small band (approximate to 60 ppm) assigned to alcoholic groups which appeared as a result of the partial reduction of carbonyl groups. Use of the pyrite-containing Bg sample in solid-state NMR investigations is found to be more favourable because of its shorter T-1H relaxation time and, consequently, shorter (by a factor of about five) experimental time. (C) 1998 Elsevier Science Ltd. All rights reserved