Preliminary mechanical characterization of the small bowel for in vivo robotic mobility

In this work we present test methods, devices, and preliminary results for the mechanical characterization of the small bowel for intra luminal robotic mobility. Both active and passive forces that affect mobility are investigated. Four investigative devices and testing methods to characterize the active and passive forces are presented in this work: (1) a novel manometer and a force sensor array that measure force per cm of axial length generated by the migrating motor complex, (2) a biaxial test apparatus and method for characterizing the biomechanical properties of the duodenum, jejunum, and ileum, (3) a novel in vitro device and protocol designed to measure the energy required to overcome the self-adhesivity of the mucosa, and (4) a novel tribometer that measures the in vivo coefficient of friction between the mucus membrane and the robot surface. The four devices are tested on a single porcine model to validate the approach and protocols. Mean force readings per cm of axial length of intestine that occurred over a 15?min interval in vivo were 1.34?±?0.14 and 1.18?±?0.22?N cm(-1) in the middle and distal regions, respectively. Based on the biaxial stress/stretch tests, the tissue behaves anisotropically with the circumferential direction being more compliant than the axial direction. The mean work per unit area for mucoseparation of the small bowel is 0.08?±?0.03 mJ cm(-2). The total energy to overcome mucoadhesion over the entire length of the porcine small bowel is approximately 0.55?J. The mean in vivo coefficient of friction (COF) of a curved 6.97 cm(2) polycarbonate sled on live mucosa traveling at 1?mm s(-1) is 0.016?±?0.002. This is slightly lower than the COF on excised tissue, given the same input parameters. We have initiated a comprehensive program and suite of test devices and protocols for mechanically characterizing the small bowel for in vivo mobility. Results show that each of the four protocols and associated test devices has successfully gathered preliminary data to confirm the validity of our test approach.     

Vitale Fluorochromierung pflanzlicher Viruseinschlußkörper

Zusammenfassung Die protoplasmatischem x-bodies von viruskrankenAichryson lassen sich mit verschiedenen Vitalfluorochromen im Fluoreszenzmikroskop deutlich hervorheben.     

Reconstructing mental object representations: a machine vision approach to human visual recognition

This paper introduces a new approach to assess visual representations underlying the recognition of objects. Human performance is modeled by CLARET, a machine learning and matching system, based on inductive logic programming and graph matching principles. The model is applied to data of a learning experiment addressing the role of prior experience in the ontogenesis of mental object representations. Prior experience was varied in terms of sensory modality, i.e. visual versus haptic versus visuohaptic. The analysis revealed distinct differences between the representational formats used by subjects with haptic versus those with no prior object experience. These differences suggest that prior haptic exploration stimulates the evolution of object representations which are characterized by an increased differentiation between attribute values and a pronounced structural encoding.     

Fine structural studies of the islets of Langerhans in the Djungarian hamster (Phodopus sungorus)

Summary A study of the pancreatic islets of Langerhans in the Djungarian hamster (Phodopus sungorus) was initiated by the observation that 98 percent of the animals of a recently established colony showed ketoacidosis soon after birth, about ten percent of which later developed persistent hyperglycemia. The islets are made up of a centrally located mass of insulin-producing B-cells surrounded by a peripheral rim of A-and D-cells. Most islets are richly supplied by unmyelinated nerve fibers which terminate on all three cell types with cholinergic synaptic endings. Early changes in islet fine structure due to ketosis comprise degranulation of A-cells combined with signs of crinophagia of -granules. After the manifestation of hyperglycemia, degranulation of B-cells is followed by deposition of glycogen which in the late phase of the diabetic syndrome forms large masses obscuring the regular cellular organelles. In six-to nine-month hyperglycemic animals degenerative changes are also observed in D-cells in the form of autophagic vacuoles.Dedicated to Professor Dr. Helmut Ferner, Vienna on the occasion of his 65th birthday     

Evaluation of conventional and four real-time PCR methods for the detection of Leishmania on field-collected samples in Ethiopia

In most low-resource settings, microscopy still is the standard method for diagnosis of cutaneous leishmaniasis, despite its limited sensitivity. In Ethiopia, the more sensitive molecular methods are not yet routinely used. This study compared five PCR methods with microscopy on two sample types collected from patients with a suspected lesion to advise on optimal diagnosis of Leishmania aethiopica. Between May and July 2018, skin scrapings (SS) and blood exudate from the lesion spotted on filter paper (dry blood spot, DBS) were collected for PCR from 111 patients of four zones in Southern Ethiopia. DNA and RNA were simultaneously extracted from both sample types. DNA was evaluated by a conventional PCR targeting ITS-1 and three probe-based real-time PCRs: one targeting the SSU 18S rRNA and two targeting the kDNA minicircle sequence (the ‘Mary kDNA PCR’ and a newly designed ‘LC kDNA PCR’ for improved L. aethiopica detection). RNAs were tested with a SYBR Green-based RT-PCR targeting spliced leader (SL) RNA. Giemsa-stained SS smears were examined by microscopy. Of the 111 SS, 100 were positive with at least two methods. Sensitivity of microscopy, ITS PCR, SSU PCR, Mary kDNA PCR, LC kDNA PCR and SL RNA PCR were respectively 52%, 22%, 64%, 99%, 100% and 94%. Microscopy-based parasite load correlated well with real-time PCR Ct-values. Despite suboptimal sample storage for RNA detection, the SL RNA PCR resulted in congruent results with low Ct-values. DBS collected from the same lesion showed lower PCR positivity rates compared to SS. The kDNA PCRs showed excellent performance for diagnosis of L. aethiopica on SS. Lower-cost SL RNA detection can be a complementary high-throughput tool. DBS can be used for PCR in case microscopy is negative, the SS sample can be sent to the referral health facility where kDNA PCR method is available.     

The development of a material model and wheel–tissue interaction for simulating wheeled surgical robot mobility

In vivo surgical robot wheel and tissue interaction was studied using a nonlinear finite element model. A liver material model, derived from laboratory experiments, was implemented as a viscoelastic material. A finite element simulation of this laboratory test confirmed the accuracy of the liver material model. This material model was then used as the tissue model to study wheel performance. A helical wheel moving on the liver model was used to replicate laboratory experiments that included several different slip ratios and applied loads. The drawbar force produced in this model showed good agreement with the physical tests. These results have provided the baseline for studying how changes in wheel geometry, such as tread height, tread spacing and wheel diameter, affect drawbar force and ultimately wheel performance. These results will be used in future surgical robot wheel designs.     

Rapid diagnostic tests as a source of DNA for Plasmodium species-specific real-time PCR

Background

To overcome the problem of increasing drug resistance, traditional medicines are an important source for potential new anti-malarials. Caesalpinia pluviosa, commonly named "sibipiruna", originates from Brazil and possess multiple therapeutic properties, including anti-malarial activity.

Methods

Crude extract (CE) was obtained from stem bark by purification using different solvents, resulting in seven fractions. An MTT assay was performed to evaluate cytotoxicity in MCF-7 cells. The CE and its fractions were tested in vitro against chloroquine-sensitive (3D7) and -resistant (S20) strains of Plasmodium falciparum and in vivo in Plasmodium chabaudi-infected mice. In vitro interaction with artesunate and the active C. pluviosa fractions was assessed, and mass spectrometry analyses were conducted.

Results

At non-toxic concentrations, the 100% ethanolic (F4) and 50% methanolic (F5) fractions possessed significant anti-malarial activity against both 3D7 and S20 strains. Drug interaction assays with artesunate showed a synergistic interaction with the F4. Four days of treatment with this fraction significantly inhibited parasitaemia in mice in a dose-dependent manner. Mass spectrometry analyses revealed the presence of an ion corresponding to m/z 303.0450, suggesting the presence of quercetin. However, a second set of analyses, with a quercetin standard, showed distinct ions of m/z 137 and 153.

Conclusions

The findings show that the F4 fraction of C. pluviosa exhibits anti-malarial activity in vitro at non-toxic concentrations, which was potentiated in the presence of artesunate. Moreover, this anti-malarial activity was also sustained in vivo after treatment of infected mice. Finally, mass spectrometry analyses suggest that a new compound, most likely an isomer of quercetin, is responsible for the anti-malarial activity of the F4.