Neurotensin changes the motor pattern in canine ileum from propulsive to segmenting

Modulation of ileal propulsive motility by different doses of neurotensin has been determined in detail. In conscious dogs neurotensin (2.5, 5, and 10 pmol/kg/min) was intravenously infused during the propulsive motor pattern induced by an acaloric viscous meal. Motor patterns were recorded by seven closely spaced strain gauge transducers and analyzed by a computerized method. Luminal transit was measured fluoroscopically. Neurotensin changed the propulsive motor pattern induced by the acaloric meal into a segmenting pattern. Effects were dose-dependent and most striking at a dose of 10 pmol/kg/min. The transit of luminal contents decreased from 20 to 8 cm/min. This was achieved by the increase in the number of stationary contractions (31 vs 55%), the reduction in the length of contraction spread (3.8 vs 1.8 cm), and the decrease in the number of contractions (11.5 vs 9.2 contractions/min). The contraction force was enhanced from 67 to 107 mN. Because of the marked effects on ileal motor patterns, neurotensin might be involved in the regulation of digestive motility in the distal small intestine.This study was supported by the Deutsche Forschungsgemeinschaft Grant Eh 64/4-2.     

Prevalence of and risk factors for carriage of Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus among residents and staff of a German nursing home.

The aims of this cross-sectional study were to determine the prevalence of and risk factors for carriage of Panton-Valentine leukocidin-producing methicillin-resistant Staphylococcus aureus (PVL-MRSA) in residents and personnel of a nursing home in Germany. In this study, PVL-MRSA carriage status among nursing home residents was associated with risk factors reflecting their dependence on nursing care. No specific risk factors were detected among staff.     

The sodium concentration of enteral diets does not influence absorption of nutrients but induces intestinal secretion of water in miniature pigs

Contradictory opinions exist as to whether the sodium concentration of enteral diets influences absorption of macronutrients and transepithelial movement of sodium and water. Therefore, we investigated the effects of various sodium concentrations of enteral diets on absorption of macronutrients and on net fluxes of sodium and water. In unanesthetized miniature pigs, a 150-cm jejunal segment was perfused with an oligopeptide (Peptisorb), an oligomeric and a polymeric diet. The polymeric diet was supplemented with pancreatic enzymes. The sodium concentrations varied between 30 and 150 mmol/L. The energy density was 3.4 MJ/L. The sodium concentration of the diets did not influence absorption of macronutrients and of total energy. However, increasing sodium concentrations of the diets were associated with increasing osmolality of the solutions, resulting in a linear increase in net secretion of water and flow rate of chyme. With all diets and sodium concentrations net secretion of sodium occurred. The sodium secretion was independent of the initial sodium concentration of the diets. It was linearly correlated with net flux of water and was largest in miniature pigs infused with the oligomeric diet. The sodium concentration of the jejunal effluent did not correspond to the initial sodium concentration of the diets. The present results indicate that enteral feeding of diets with high energy density inevitably increases net secretion of water and sodium as sodium concentration increases. Therefore, the sodium concentration of diets should be as low as possible to meet only the minimal daily requirement of sodium. Low sodium concentrations of diets have no negative effects on absorption of macronutrients.     

Repair, regenerative and supportive therapies of the annulus fibrosus: achievements and challenges

Lumbar discectomy is a very effective therapy for neurological decompression in patients suffering from sciatica due to hernia nuclei pulposus. However, high recurrence rates and persisting post-operative low back pain in these patients require serious attention. In the past decade, tissue engineering strategies have been developed mainly targeted to the regeneration of the nucleus pulposus (NP) of the intervertebral disc. Accompanying techniques that deal with the damaged annulus fibrous are now increasingly recognised as mandatory in order to prevent re-herniation to increase the potential of NP repair and to confine NP replacement therapies. In the current review, the requirements, achievements and challenges in this quickly emerging field of research are discussed. Dedicated to the memory of Prof. Dr. Paul I. J. M. Wuisman.     

Mechanical characteristics of phase II and phase III of the interdigestive migrating motor complex in dogs

In conscious dogs certain parameters of the jejunal interdigestive phase II and phase III activity were studied by means of closely spaced strain gauges and videofluoroscopy. During phase III the frequency, force, and rise time of contractions and the contraction spread were increased, whereas the intercontractile intervals and the propagation velocity of contractions were diminished in comparison to phase II. The contraction waves of phase III were variable with regard to their length of spread and their rate of caudad migration. These two parameters adjusted the duration, the propagation velocity, and the length of the activity front. Propagation of contractions was sometimes interrupted by periods of uncoupling. Propagation velocities within contraction waves varied according to the pattern slow-fast-slow-fast, producing the videofluoroscopically observed roller coaster movements of the luminal contents. It is concluded that phase II and phase III are characterized not only by the occurrence of irregular and regular activity but by a significant change of a number of contraction parameters.     

Preclinical comparison of mTHPC and verteporfin for intracavitary photodynamic therapy of malignant pleural mesothelioma

Efficacy and tumour selectivity of photodynamic therapy with two clinically approved sensitizers (mTHPC, verteporfin) were assessed for focal intracavitary photodynamic therapy (PDT) in rodents with malignant pleural mesothelioma (MPM) at recommended drug-light conditions and at escalating sensitizer dosages. MPM tumours were generated in 15 Fischer rats by subpleural mediastinal tumour cell injection followed after 5 days by intracavitary PDT with light delivery monitored by in situ dosimetry. Animals were intravenously sensitized either with mTHPC (0.1 mg/kg, n = 3; 0.2 mg/kg, n = 3) followed after 4 days by illumination with 20 J/cm(2) at 652 nm, or with verteporfin (0.6 mg/kg, n = 3; 1.2 mg/kg, n = 3) followed after 20 min by illumination with 100 J/cm(2) at 689 nm. Three untreated tumour-bearing animals served as controls. Histological evaluation of the treated tumour and of adjacent normal organs was performed 10 days after tumour implantation. The extent of PDT-induced tumour necrosis was compared to the non-necrosed area and expressed in percentage. A locally invasive growing MPM tumour (3.1 +/- 1 mm diameter) without spontaneous necrosis diameter was found in all animals. For both sensitizers, focal intracavitary PDT was well tolerated at drug-light conditions recommended for clinical applications. Mediastinal organs were spared for both sensitizers but verteporfin resulted in a higher extent of tumour necrosis (80%) than mTHPC (50%). Drug dose escalation revealed a higher extent of PDT-related tumour necrosis for both sensitizers (mTHPC 55%, verteporfin 88%), however, verteporfin-PDT was associated with a higher toxicity than mTHPC-PDT.     

Computerised method for pattern recognition of intestinal motility: Functional significance of the spread of contractions

The intestinal motility consists of local and propagative contractions. A system for determining the length of spread of intestinal contractions has been developed. The technique used for waveform recognition was based on the principle of peak detection. A computer program analysed the length of spread of contractile waves, their mean contractile force and their mean propagation velocity. The computer identified each waveform on the basis of pre-established threshold and timing criteria. A technique for fitting theoretical equations to experimental data (measured transit rate of ingesta against evaluated parameters) was used to prove the functional significance of the contractile patterns. The method provides a more detailed representation of contractile patterns than other studies based on the conventional methods of analysis.     

Malignantly transformed non-parenchymal liver epithelial cells and transformed oval cells suppress the homotypical gap junctional intercellular communication of co-cultured rat liver parenchymal cells

Isolated rat liver parenchymal cells (PC) were co-cultured witha non-parenchymal rat liver epithelial cell line (NEC) or withan oval cell line. The homotypical gap junctional intercellularcommunication (GJIC) between the liver PC was measured aftermicroinjection of Lucifer Yellow by dye transfer. The rat liverPC were dye coupled between 87% and 100% for at least 1 weekin both co-cultures, in contrast to PC in monoculture betweenwhich no dye coupling was left after 1 week. When liver PC wereco-cultured with a transformed and tumorigenic NEC or with atransformed and tumorigenic oval cell line the homotypical GJICbetween the liver PC was drastically decreased with culturetime, and the PC were then compressed and displaced by the expansivegrowth of the transformed cell lines. The disturbance of theGJIC between normal cells by adjacent tumorigenic cells mightbe a new mechanism to explain the expansive growth of tumors.