An Integrated Deposition and Passivation Strategy for Controlled Crystallization of 2D/3D Halide Perovskite Films

This work introduces a simplified deposition procedure for multidimensional (2D/3D) perovskite thin films, integrating a phenethylammonium chloride (PEACl)-treatment into the antisolvent step when forming the 3D perovskite. This simultaneous deposition and passivation strategy reduces the number of synthesis steps while simultaneously stabilizing the halide perovskite film and improving the photovoltaic performance of resulting solar cell devices to 20.8%. Using a combination of multimodal in situ and additional ex situ characterizations, it is demonstrated that the introduction of PEACl during the perovskite film formation slows down the crystal growth process, which leads to a larger average grain size and narrower grain size distribution, thus reducing carrier recombination at grain boundaries and improving the device's performance and stability. The data suggests that during annealing of the wet film, the PEACl diffuses to the surface of the film, forming hydrophobic (quasi-)2D structures that protect the bulk of the perovskite film from humidity-induced degradation.

Unraveling the Role of Perovskite in Buried Interface Passivation

Interfaces in perovskite solar cells play a crucial role in their overall performance, and therefore, detailed fundamental studies are needed for a better understanding. In the case of the classical n-i-p architecture, TiO2 is one of the most used electron-selective layers and can induce chemical reactions that influence the performance of the overall device stack. The interfacial properties at the TiO2/perovskite interface are often neglected, owing to the difficulty in accessing this interface. Here, we use X-rays of variable energies to study the interface of (compact and mesoporous) TiO2/perovskite in such a n-i-p architecture. The X-ray photoelectron spectroscopy and X-ray absorption spectroscopy methods show that the defect states present in the TiO2 layer are passivated by a chemical interaction of the perovskite precursor solution during the formation of the perovskite layer and form an organic layer at the interface. Such passivation of intrinsic defects in TiO2 removes charge recombination centers and shifts the bands upward. Therefore, interface defect passivation by oxidation of Ti3+ states, the organic cation layer, and an upward band bending at the TiO2/perovskite interface explain the origin of an improved electron extraction and hole-blocking nature of TiO2 in the n-i-p perovskite solar cells.

Coordination Chemistry as a Universal Strategy for a Controlled Perovskite Crystallization

The most efficient and stable perovskite solar cells (PSCs) are made from a complex mixture of precursors. Typically, to then form a thin film, an extreme oversaturation of the perovskite precursor is initiated to trigger nucleation sites, e.g., by vacuum, an airstream, or a so-called antisolvent. Unfortunately, most oversaturation triggers do not expel the lingering (and highly coordinating) dimethyl sulfoxide (DMSO), which is used as a precursor solvent, from the thin films; this detrimentally affects long-term stability. In this work, (the green) dimethyl sulfide (DMS) is introduced as a novel nucleation trigger for perovskite films combining, uniquely, high coordination and high vapor pressure. This gives DMS a universal scope: DMS replaces other solvents by coordinating more strongly and removes itself once the film formation is finished. To demonstrate this novel coordination chemistry approach, MAPbI3 PSCs are processed, typically dissolved in hard-to-remove (and green) DMSO achieving 21.6% efficiency, among the highest reported efficiencies for this system. To confirm the universality of the strategy, DMS is tested for FAPbI3 as another composition, which shows higher efficiency of 23.5% compared to 20.9% for a device fabricated with chlorobenzene. This work provides a universal strategy to control perovskite crystallization using coordination chemistry, heralding the revival of perovskite compositions with pure DMSO.

WO3 Thin-Film Optical Gas Sensors Based on Gasochromic Effect towards Low Hydrogen Concentrations

Hydrogen gas sensors have recently attracted increased interest due to the explosive nature of H₂ and its strategic importance in the sustainable global energy system. In this paper, the tungsten oxide thin films deposited by innovative gas impulse magnetron sputtering have been investigated in terms of their response to H₂. It was found that the most favourable annealing temperature in terms of sensor response value, as well as response and recovery times, was achieved at 673 K. This annealing process caused a change in the WO₃ cross-section morphology from a featureless and homogenous form to a rather columnar one, but still maintaining the same surface homogeneity. In addition to that, the full-phase transition from an amorphous to nanocrystalline form occurred with a crystallite size of 23 nm. It was found that the sensor response to only 25 ppm of H₂ was equal to 6.3, which is one of the best results presented in the literature so far of WO₃ optical gas sensors based on a gasochromic effect. Moreover, the results of the gasochromic effect were correlated with the changes in the extinction coefficient and the concentration of the free charge carriers, which is also a novel approach to the understanding of the gasochromic phenomenon.

Hydrogen Gas Sensing Properties of Mixed Copper-Titanium Oxide Thin Films

Hydrogen is an efficient source of clean and environmentally friendly energy. However, because it is explosive at concentrations higher than 4%, safety issues are a great concern. As its applications are extended, the need for the production of reliable monitoring systems is urgent. In this work, mixed copper-titanium oxide ((CuTi)Ox) thin films with various copper concentrations (0-100 at.%), deposited by magnetron sputtering and annealed at 473 K, were investigated as a prospective hydrogen gas sensing material. Scanning electron microscopy was applied to determine the morphology of the thin films. Their structure and chemical composition were investigated by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The prepared films were nanocrystalline mixtures of metallic copper, cuprous oxide, and titanium anatase in the bulk, whereas at the surface only cupric oxide was found. In comparison to the literature, the (CuTi)Ox thin films already showed a sensor response to hydrogen at a relatively low operating temperature of 473 K without using any extra catalyst. The best sensor response and sensitivity to hydrogen gas were found in the mixed copper-titanium oxides containing similar atomic concentrations of both metals, i.e., 41/59 and 56/44 of Cu/Ti. Most probably, this effect is related to their similar morphology and to the simultaneous presence of Cu and Cu₂O crystals in these mixed oxide films. In particular, the studies of surface oxidation state revealed that it was the same for all annealed films and consisted only of CuO. However, in view of their crystalline structure, they consisted of Cu and Cu₂O nanocrystals in the thin film volume.

History of Polish Canidae (Carnivora, Mammalia) and Their Biochronological Implications on the Eurasian Background

The remains of 12 canid species that date back ca. 4.9 myr have been found at 116 paleontological localities. Among these localities, eight are dated to the Pliocene age, 12 are dated to the Early Pleistocene age, 12 are from the Middle Pleistocene age, while the most numerous group includes 84 sites from the Late Pleistocene–Holocene age. Some, especially older forms such as Eucyon odessanus and Nyctereutes donnezani, have only been found at single sites, while the remains of species from the genus Lycaon, Canis and Vulpes have been recorded at numerous sites from the last 2 myr. Ancient canids such as Eucyon and Nyctereutes had already vanished from Poland in the Earliest Pleistocene, between 2.5 and 2.2 myr ago. Poland’s extant canid fauna is characterised by the presence of two new species, which spread into the territory due to a human introduction (Nyctereutes procyonoides) or natural expansion (Canis aureus). Research indicates a strong competition between dogs, especially between Lycaon, Canis and Cuon, with a strong lycaon-limiting effect on the wolf between 2.5 and 0.4 myr ago. After the extinction of Lycaon lycaonoides, Canis lupus evolved rapidly, increasing in number and size, and taking over the niche occupied by Lycaon. In order to reduce competition, the body size of Cuon alpinus gradually reduced, and it became an animal adapted to the forest, highland and mountain environments. Generally, the history of canids in Poland is similar to that known of Eurasia with some noteworthy events, such as the early occurrence of Canis cf. etruscus from Węże 2 (2.9–2.6 myr ago), Lycaon falconeri from Rębielice Królewskie 1A or one of the latest occurrences of L. lycaonoides from Draby 3 (430–370 kyr). Predominantly lowland or upland in the southern part and devoid of significant ecological barriers, Poland is also an important migration corridor in the East–West system. This 500–600 km wide corridor was the Asian gateway to Europe, from where species of an eastern origin penetrated the continent’s interior. In colder periods, it was in turn a region through which boreal species or those associated with the mammoth steppe retreated.

Wear mechanisms description in nanoscale by SEM/TEM of multilayer Zr/ZrN coatings in dependence on phases ratio

As a result of loading with an external force during the wear process, coating deforms uniformly. After a certain limit load is exceeded, coating deformation is localised through the formation of the so-called shear bands. It has been showed experimentally the process of shear bands formation. The microstructural characterisation before and after the mechanical tests was performed using scanning and transmission electron microscopy (SEM and TEM) on cross-sections of the samples. The analysis indicated that in the case of multilayer coatings where the ratio of the metallic to the ceramic phase is 1:1, the shear bands are formed at an angle of 45°. With a greater proportion of the ceramic phase to metallic (ratio 1:2), the shear band changed the shear angle from ∼45° to ∼90°. Mechanical in situ tests were carried out in the chambers of SEM and TEM. The scratch tests in the SEM were done with the simultaneous observation of the phenomena occurring on the surface of the tested materials showed that at a scratch force of 0.04 N, the additional outer a-C:H layer was damaged, which was shown in the form of a fault in the force-displacement diagram, and in the form of splits visible in the SEM image. However, the application of this additional layer had a positive effect on the wear mechanism of the entire coating structure. The test also indicated that in the case of coatings with phases ratio 1:2 and 1:4 (metallic to ceramic), the characteristics of the brittle material were demonstrated, unlike the coating with a 1:1 phase ratio, where plastic properties predominated. However, for the 1:2 phase ratio coating, the chip was more ductile than for the chip formed when testing a 1:4 phase ratio coating. For in situ mechanical testing in the TEM, a straining holder was used. The test showed that the shear band angle for a 1:1 ratio coating has changed from 45° to 90° due to the different direction of force interaction.

Frontiers of the Lower Palaeolithic expansion in Europe: Tunel Wielki Cave (Poland)

Peopling of Central Europe by Middle Pleistocene hominids is highly debatable, mainly due to the relatively harsh climatic and environmental conditions that require cultural and anatomical adjustments. At least several archaeological sites certify human occupation in the region dated back to MIS 13-11, but they represent open-air settlements. Based on the new fieldwork conducted in Tunel Wielki Cave, we can date the human occupation traces in the cave to MIS 14-12. Bipolar-on-anvil knapping technique prevails in the lithic assemblage, made exclusively in flint. The obtained results have given ground for studying the frontiers of human oikumene and the required cultural adaptive abilities.

Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation

The electronic band alignment of an alumina/zinc oxide thin-film heterostructure solely grown by atomic layer deposition has been determined by XPS/UPS depth profiling, correlating the electronic properties with the interface chemical composition.

Small-molecule inhibitor - tyrphostin AG1296 regulates proliferation, survival and migration of rhabdomyosarcoma cells

Rhabdomyosarcoma (RMS) is the most commonly occurring malignant soft tissue tumor in children. Despite improving its treatment methods, the current outcome in the advanced stages of this tumor is not satisfactory. RMS cells are characterized by abnormal cellular signaling due to the changes in the activity of the tyrosine kinases. Thus, substances blocking the mitogenic signal transmitted by receptors with tyrosine kinase activity raise hopes for inhibition of the uncontrolled cell growth. In this study, we examined the anticancer activity of tyrphostin AG1296, a tyrosine kinase inhibitor that binds to the intracellular domain of the PDGF (platelet-derived growth factor) receptor in human RMS alveolar and embryonal cell lines. We have discovered that tyrphostin AG1296 completely inhibited cell proliferation and effectively inhibited cell viability. Tyrphostin AG1296 induced apoptosis of the RMS cells and significantly inhibited their migration. Additionally, investigated inhibitor slightly inhibited expression of AKT and phosphorylation of ERK in alveolar RMS cells. Importantly, the inhibitor exerted also potent effects on the nanomechanical properties and cytoskeleton organization of RMS cells. To conclude, tyrphostin AG1296 is a promising compound in the treatment of alveolar RMS. Undoubtedly, a better knowledge of receptor pathomechanism of tyrosine kinases may contribute to developing new, more effective ways of RMS treatment.

In situ Near-Ambient Pressure X-ray Photoelectron Spectroscopy Reveals the Influence of Photon Flux and Water on the Stability of Halide Perovskite

For several years, scientists have been trying to understand the mechanisms that reduce the long-term stability of perovskite solar cells. In this work, we examined the effect of water and photon flux on the stability of CH3 NH3 PbI3 perovskite films and solar cells using in situ near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), field emission scanning electron microscopy (FESEM), and current density-voltage (J-V) characterization. The used amount of water vapor (up to 1 mbar) had a negligible impact on the perovskite film. The higher the photon flux, the more prominent were the changes in the NAP-XPS and FESEM data; also, a faster decline in power conversion efficiency (PCE) and a more substantial hysteresis in the J-V characteristics were observed. Based on our results, it can be concluded that the PCE decrease originates from the creation of Frenkel pair defects in the perovskite film under illumination. The stronger the illumination, the higher the number of Frenkel defects, leading to a faster PCE decline and more substantial hysteresis in the J-V sweeps.

Effect of the mechanical properties of carbon-based coatings on the mechanics of cell-material interactions

The paper presents an influence of the surface mechanical properties of thin-film materials on blood cell adhesion under shear stress conditions. Physical vapour deposited (PVD) coatings i.e. hydrogenated amorphous carbon (a-C:H) doped with nitrogen or silicon have been investigated. The mechanical properties of materials, namely their microhardness and Young's modulus were measured using indentation test with Rockwell indenter. The adhesion efficiency of blood cells in dynamic conditions were analysed using a radial flow chamber. Red blood cells (RBC) were used as representative cells to analyse cell-material interactions. The biomaterial examinations were performed under physiological flow conditions at the single-cell level. The 3D FVM (finite volume method) model of multi-phase radial flow test was developed to reproduce the physical test and to predict distributions of shear stresses and velocity during blood washout with PBS. Cell-material interactions were found to be strongly associated with the mechanical properties of the thin-film material. The decrease in the hardness of the coatings translated into a weaker cell - material interactions.

Microwave-assisted synthesis and characterization of novel chitosan-based biomaterials for pelvic organ prolapse treatment

Pelvic organ disorders affect up to one in four women in the United States. The prevalence of pelvic organ prolapse (POP) is increasing with each year, particularly in the setting of prolonged life expectancy and an aging population. Current treatment approaches, including polypropylene monofilaments are associated with numerous painful and worrisome side-effects. Therefore, scientists are looking for new solutions. A promising alternative to the current treatment is tissue engineering, which can be utilized to re-create support to the vagina and pelvic organs. Tissue engineering requires the use of three-dimensional scaffolds, derived from biocompatible materials. Chitosan is a natural polymer, obtained from shellfish exoskeletons. It is known for its biodegradability, lack of cytotoxicity and non-pyrogenicity. Due to the presence of free hydroxyl and amino groups, it may undergo various modifications. In this paper, we describe a new type of chitosan-based biomaterials, which can be used as a new alternative scaffold that may provide support to prolapse organs. The chitosan scaffold was obtained under microwave radiation using multifunctional amino and organic acids. We discuss the scaffold's characteristics, with an emphasis on its chemical structure and morphology. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed cross-linking processes with preservation of free amino groups. Moreover, mechanical durability, the stability and swelling ability of the scaffolds in a simulated body fluid were investigated. All of the prepared scaffolds demonstrated very good antioxidant activity and biodegradability. Importantly, the biocompatibility of chitosan scaffolds was examined on human vaginal VK2/E6E7 cell line. No evidence of toxicity was documented, and the cells maintained their presence on the studied materials. These results allude to the lack of toxicity of the scaffolds, and indicate that chitosan-based scaffold should be further investigated in in vivo studies as they may be a promising alternative treatment to pelvic organ prolapse.

Evidence of Nitrogen Contribution to the Electronic Structure of the CH3 NH3 PbI3 Perovskite

Despite fast development of hybrid perovskite solar cells, there are many fundamental questions related to the perovskite film which remain open. For example, there are contradicting theoretical reports on the role of the organic methylammonium cation (CH₃ NH₃⁺ ) in the methylammonium lead triiodide (CH₃ NH₃ PbI₃ ) perovskite film. From one side it is reported that the organic cation does not contribute to electronic structure of the CH₃ NH₃ PbI₃ film. From the other side, valence band maximum fluctuations, dependent on the CH₃ NH₃⁺ rotation, have been theoretically predicted. The resonant X-ray photoelectron spectroscopy results reported here show experimental evidence of nitrogen contribution to the CH₃ NH₃ PbI₃ electronic structure. Moreover, the observed strong resonances of nitrogen with the I 5s and the Pb 5d-6s levels indicate that the CH₃ NH₃ PbI₃ valence band is extended up to ≈18 eV below the Fermi energy, and therefore one should also consider these shallow core levels while modeling its electronic structure.

Understanding the growth mechanism of graphene on Ge/Si(001) surfaces

The practical difficulties to use graphene in microelectronics and optoelectronics is that the available methods to grow graphene are not easily integrated in the mainstream technologies. A growth method that could overcome at least some of these problems is chemical vapour deposition (CVD) of graphene directly on semiconducting (Si or Ge) substrates. Here we report on the comparison of the CVD and molecular beam epitaxy (MBE) growth of graphene on the technologically relevant Ge(001)/Si(001) substrate from ethene (C₂H₄) precursor and describe the physical properties of the films as well as we discuss the surface reaction and diffusion processes that may be responsible for the observed behavior. Using nano angle resolved photoemission (nanoARPES) complemented by transport studies and Raman spectroscopy as well as density functional theory (DFT) calculations, we report the direct observation of massless Dirac particles in monolayer graphene, providing a comprehensive mapping of their low-hole doped Dirac electron bands. The micrometric graphene flakes are oriented along two predominant directions rotated by 30° with respect to each other. The growth mode is attributed to the mechanism when small graphene “molecules” nucleate on the Ge(001) surface and it is found that hydrogen plays a significant role in this process.

Melatonin metabolite, N(1)-acetyl-N(1)-formyl-5-methoxykynuramine (AFMK), attenuates acute pancreatitis in the rat: in vivo and in vitro studies

Melatonin protects the pancreas from inflammation and free radical damage but the effect of the melatonin metabolite: N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) on acute pancreatitis is unknown. This study assessed the effects of AFMK on acute pancreatitis (AP) in the rats in vivo and on pancreatic cell line AR42J in vitro. AFMK (5, 10 or 20 mg/kg) was given intraperitoneally to the rats 30 min prior to the induction of AP by subcutaneous caerulein infusion (25 μg/kg). Lipid peroxidation products (MDA + 4-HNE) and the activity of an antioxidant enzyme glutathione peroxidase (GPx) were measured in pancreatic tissue. Blood samples were taken for evaluation of amylase activity and TNF-α concentration. GPx, TNF-α, proapoptotic Bax protein, antiapoptotic Bcl-2 protein and the executor of apoptosis, caspase-3, were determined by Western blot in AR42J cells subjected to AFMK or to melatonin (both used at 10(-12), 10(-10), or 10(-8)M), without or with addition of caerulein (10(-8)M). AP was confirmed by histological examination and by serum increases of amylase and TNF-α (by 800% and 300%, respectively). In AP rats, pancreatic MDA + 4-HNE levels were increased by 300%, whereas GPx was reduced by 50%. AFMK significantly diminished histological manifestations of AP, decreased serum amylase activity and TNF-α concentrations, reduced MDA + 4-HNE levels and augmented GPx in the pancreas of AP rats. In AR42J cells, AFMK combined with caerulein markedly increased protein signals for GPx, Bax, caspase-3 and reduced these for TNF-α and Bcl-2. In conclusion, AFMK significantly attenuated acute pancreatitis in the rat. This may relate to the antioxidative and anti-inflammatory effects of this molecule and possibly to the stimulation of proapoptotic signal transduction pathway.

Inflammation increases oxidative DNA damage repair and stimulates preneoplastic changes in colons of newborn rats

Oxidative DNA damage may be a risk factor for development of various pathologies, including malignancy. We studied inflammation triggered modulation of repair activity in the intestines of three weeks old rats injected i.p. with E.coli or S. typhimurium lipopolysaccharides (LPS) at doses of 1, 5 or 10 mg/kg. Subsequent formation in these animals of colonic preneoplastic lesions, aberrant crypt foci (ACF) was also investigated. Five days after LPS administration no differences were observed in repair rate of 1,N(6)-ethenoadenine (εA), 3,N(4)-ethenocytosine (εC) and 8-oxoguanine (8-oxoG) in intestines of these rats, as measured by the nicking assay. However a significant increase in all three repair activities was found within one and two months after S. typhimurium LPS treatment. E. coli LPS significantly increased only the 8-oxoG repair. S. typhimurium LPS stimulated mRNA transcription of pro-inflammatory proteins, lipooxygenase-12 and cyclooxygenase-2, as well as some DNA repair enzymes like AP-endonuclease (Ape1) and εC-glycosylase (Tdg). mRNA level of DNA glycosylases excising εA (MPG) and 8-oxoG (OGG1) was also increased by LPS treatment, but only at the highest dose. Transcription of all enzymes increased for up to 30 days after LPS, and subsequently decreased to the level observed before treatment, with the exception of APE1, which remained elevated even two months after LPS administration. Thus, the repair efficiency of εA, εC and 8-oxoG depends on the availability of APE1, which increases OGG1 and TDG turnover on damaged DNA, and presumably stimulates MPG. One and two months after administration of E. coli or S. typhimurium LPS, the number of aberrant crypt foci in rat colons increased in a dose and time dependent manner. Thus, inflammation stimulates the repair capacity for εA, εC and 8-oxoG, but simultaneously triggers the appearance of preneoplastic changes in the colons. This may be due to increased oxidative stress and imbalance in DNA repair.

Development and complex characterization of bio-tribological Cr/CrN + a-C:H (doped Cr) nano-multilayer protective coatings for carbon–fiber-composite materials

Microstructure characterization of an as deposited coating; (a) image obtained using SEM; (b) image done by TEM technique in STEM mode. Microstructure characterization of the coating at the cross-section, done by TEM; (a) TEM BF image; (b) STEM image.

Comparison of Cardiac Output Measurements in Critically Ill Patients: Flotrac/Vigileo Vs Transthoracic Doppler Echocardiography

Measurement of cardiac output is an integral part of patient management in the intensive care unit. FloTrac/Vigileo is a continuous cardiac output monitoring device that does not need re-calibration. However, its reliability has been questioned in some studies, especially involving surgical patients. In this study, we evaluated the comparability of FloTrac/Vigileo and transthoracic Doppler echocardiography in 53 critically ill patients requiring continuous cardiac output monitoring. Most of these patients had septic or cardiogenic shock. Cardiac output was measured by both FloTrac/Vigileo and transthoracic Doppler echocardiography. The bias and precision (mean and SD) between the two devices was 0.35±1.35 l/minute. The limits of agreement were -2.3 to 3.0 l/minute (%error=49.3%). When patients with irregular heart rhythms and aortic stenosis were excluded, the bias and precision was 0.02±0.80 l/minute (n=42). The limits of agreement were -1.55 to 1.59 l/minute (%error=29.5%). Patient demographics (body surface area, gender and age) did not affect the bias, but there was a mild tendency for FloTrac/Vigileo to register a higher cardiac output at high heart rates. Changes in cardiac output for two consecutive days correlated well between the two methods (r=0.86; P <0.001). In summary, with the exceptions of patients with irregular heart rhythms and significant aortic stenosis, FloTrac/Vigileo is clinically comparable to transthoracic Doppler echocardiography in cardiac output measurements in critically ill patients.

Effect of neonatal endotoxemia on the pancreas of adult rats

Bacterial endotoxin (lipopolysaccharide, LPS), is the component of the cellular wall of Gram negative bacteria. Endotoxemia (sepsis) could produce multiorgan failure and could be particularly danger in the early period of life. The effects of endotoxemia induced in the neonatal period of life on the pancreatic secretory function and on pancreatic defense of adult organism have not been investigated yet. To induce endotoxemia suckling rats (30 g) have been injected intraperitoneally with LPS from E. coli (5, 10 or 15 mg/kg-day) during 5 consecutive days. Three months later in these animals (300 g) the studies on pancreatic secretion and acute pancreatitis were carried out. In the adult rats, which have been subjected in infancy to endotoxemia, basal pancreatic secretion was unaffected, whereas amylase secretions stimulated by caerulein or by diversion of pancreatic-biliary juice to the exterior were significantly, and dose-dependently reduced as compared to the untreated control. In the rats pretreated with LPS in the suckling period of life caerulein-induced amylase release from isolated pancreatic acini was significantly decreased, and dose-dependent reduction of mRNA signal for CCK1 receptor on pancreatic acini have been observed. Caerulein infusion (25 microg/kg) produced caerulein induced pancreatitis (AP) in all animals tested, that was confirmed by histological examination. In the rats, which have been subjected in the neonatal period of life to LPS (10 or 15 mg/kg-day x 5 days) all manifestations of AP have been reduced. In these animals acute inflammatory changes of pancreatic tissue have been significantly diminished. Pancreatic weight and plasma lipase activity, have been markedly decreased in these animals as compared to the control rats, subjected in the infancy to saline injection instead of LPS. Caerulein-induced fall in an antioxidative enzyme; SOD concentration was reversed and accompanied by significant reduction of lipid peroxidation products; MDA+ 4 HNE in the pancreatic tissue.

CONCLUSIONS

1/ neonatal endotoxemia reduces gene expression for CCK1 receptor and could produce impairment of the exocrine pancreatic function at adult age; 2/ Prolonged exposition of suckling rats to bacterial endotoxin attenuated acute pancreatitis induced in these animals at adult age and this effect could be related to the increased concentration of antioxidative enzyme SOD in the pancreatic tissue.

Melatonin as modulator of pancreatic enzyme secretion and pancreatoprotector

Melatonin, the main product of the pineal gland, is also released from the gastrointestinal endocrine-neurocrine (EE) cells. The concentrations of melatonin produced in the gut exceeds that originating from central nervous system. In spite of the presence of melatonin receptors in the pancreatic tissue little is known about the role of this indole in the pancreas. Our experimental studies have shown that exogenous melatonin, as well as this produced endogenously from its precursor; L-tryptophan, strongly stimulates pancreatic amylase secretion when given intraperitoneally, or into the gut lumen. This was accompanied by significant increases of CCK plasma level. Above pancreatostimulatory effects of luminal administration of melatonin, were completely reversed by bilateral vagotomy, capsaicin deactivation of sensory nerves or pretreatment of the rats with CCK1 receptor antagonist; tarazepide as well as serotonin antagonist; ketanserin. Melatonin, as well as its precursor; L-tryptophan, effectively protects the pancreas against the damage induced by caerulein overstimulation or ischemia/reperfusion. The beneficial effects of melatonin or L-tryptophan on acute pancreatitis could be related to the ability of melatonin to scavenge the free radicals, to activate antioxidative enzymes and to modulate the cytokine production.

Involvement of vagal nerves in the pancreatostimulatory effects of luminal melatonin, or its precursor L-tryptophan. Study in the rats

Melatonin, known as a product of pineal gland is also produced in the digestive system. Melatonin receptors have been detected on pancreatic beta cells and this indoloamine influences the endocrine pancreatic function but the role of melatonin on pancreatic exocrine secretion is not known.

AIM

To evaluate the effects of intraduodenal administration of melatonin or its precursor L-tryptophan on pancreatic protein output under basal conditions or following the stimulation of exocrine pancreas with diversion of pancreato-bliliary juice (DBPJ) and to assess the involvement of vagal nerves, and CCK in this process.

METHODS

Under pentobarbiturate anesthesia the Wistar rats weighting 300g were surgically equipped with silicone catheters, one of them was inserted into pancreato-biliary duct, the other one--into duodenum. Melatonin (1, 5 or 25 mg/kg) or L-tryptophan (10, 50 or 250 mg/kg) were administered to the rats as intraduodenal (i.d.) bolus injection. Bilateral vagotomy was performed in the group of animals 7 days before the experiment. To assess the role of CCK in the melatonin or L-tryptophan-induced pancreatic secretory functions, lorglumide, the CCK(1) receptor antagonist was administered at dose of 1 mg/kg i.d. 15 minutes before the application of examine substances. During the study samples of pancreato-biliary juice were collected in 15 minutes aliquots to measure the protein outputs.

RESULTS

Melatonin (1, 5, or 25 mg/kg ) or L-tryptophan (10, 50 or 250 mg/kg) produced significant and dose-dependent increases in pancreatic protein secretion under basal conditions or following the stimulation of this secretion by DBPJ. This was accompanied by a dose-dependent rise in CCK plasma level. Stimulation of pancreatic protein outputs caused by melatonin or L-tryptophan was completely abolished by vagotomy, or pretreatment with lorglumide. We conclude that melatonin as well as its precursor L-tryptophan, stimulates pancreatic exocrine function via mechanisms involving enteropancreatic reflexes and CCK.

Endotoxemia in the infant rats modulates HSP60 protein level in the pancreatic acinar cells

Lipopolysaccharide (endotoxin, LPS) is responsible for septic shock and multiorgan failure, but pretreatment of the rats with low doses of LPS reduced pancreatic damage produced by caerulein-induced pancreatitis (CIP). In spite of this observations the effects of LPS and caerulein on pro-apoptotic HSP60 and Bax protein expression in the pancreatic acinar cells has not been examined yet. The aim of this study was to assess the effects of endotoxemia induced in the early period of life on the pro-apoptotic nuclear HSP60 and mitochondrial Bax protein expressions detected in the pancreas of adult animals. Newborn rats (25 g) were injected with endotoxin (Escherichia coli) for 5 consecutive days, at the total doses of 25, 50 or 75 mg/kg. Control animals received injections of physiological saline. Two months later the pancreatic acinar cells were isolated from all above groups of rats and subjected to caerulein over stimulation (10(-8)M). Total nuclear HSP60 and mitochondrial Bax protein expression were isolated for Western blot and co-immunoprecipitation studies. High levels of pro-apoptotic nuclear HSP60 and mitochondrial Bax protein has been observed in the pancreatic acinar cells under basal conditions. Pretreatment of newborn rats with LPS failed to affect significantly the HSP60 and Bax protein levels in the pancreatic acini isolated from the same animals 2 months later, as compared to the control group. Caerulein stimulation significantly reduced the level of these proteins. Pretreatment of suckling rats with LPS (at the total doses of 25, 50 or 75 mg/kg) reversed above caerulein-induced suppression of pro-apoptotic nuclear HSP60 and mitochondrial Bax protein levels in the pancreatic acini obtained from adult rats. We conclude that pretreatment of suckling rats with LPS reversed the suppression of pro-apoptotic HSP60 and Bax protein levels produced by caerulein overstimulation in the pancreatic acini. This mechanism could take a part in the LPS-induced protection of the pancreatic tissue against acute damage.

Analysis of family incidence of cleft lip and/or palate

BACKGROUND

The aim of the study was to analyze family incidence of clefts and to follow the relationship between the type of cleft in a child and in its parents as well as between the sex of the child and of the affected parent.

MATERIAL/METHODS

The study comprised 540 children with cleft lip and/or palate with a positive family history of cleft. One hundred twenty-seven children were selected from this group whose mother or father had a cleft. In this group, the relationship between the type of cleft and the child's and affected parent's sex were analyzed.

RESULTS

Two groups of genetic clefts were confirmed, each with different risks of repetition: group I with cleft lip and/or palate and group II with isolated cleft palate. It was demonstrated that the type of cleft in a child depends not only on the type of cleft observed in the parent, but that there is also a great risk of incidence of a cleft in sons of mothers with cleft lip (CL) or cleft lip and palate (CLP) or fathers with cleft lip (CL) and in daughters of mothers or fathers with cleft palate (CP).

CONCLUSIONS

1. In 17% of children with cleft lip and/or palate, a positive family history was found. 2. The cleft type in a child depends not only on the type found in the mother or father, but also on the child's sex.

Endotoxemia in newborn rats attenuates acute pancreatitis at adult age

Bacterial endotoxin (lipopolysaccharide, LPS), at high concentration is responsible for sepsis, and neonatal mortality, however low concentration of LPS protected the pancreas against acute damage. The aim of this study was to investigate the effect of exposition of suckling rats to LPS on the course of acute pancreatitis at adult age. Suckling rat (30-40g) received intraperitoneal (i.p.) injection of saline (control) or LPS from Escherichia coli or Salmonella typhi (5, 10 or 15 mg/kg-day) during 5 consecutive days. Two months later these rats have been subjected to i.p. cearulein infusion (25 microg/kg) to produce caerulein-induced pancreatitis (CIP). The following parameters were tested: pancreatic weight and morphology, plasma amylase and lipase activities, interleukin 1beta (IL-1 beta), interleukin 6 (IL-6), and interleukin 10 (IL-10) plasma concentrations. Pancreatic concentration of superoxide dismutase (SOD) and lipid peroxidation products; malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) have been also measured. Caerulein infusion produced CIP in all animals tested, that was confirmed by histological examination. In the rats, which have been subjected in the neonatal period of life to LPS at doses 10 or 15 mg/kg-day x 5 days, all manifestations of CIP have been reduced. In these animals acute inflammatory infiltration of pancreatic tissue and pancreatic cell vacuolization have been significantly diminished. Also pancreatic weight, plasma lipase and alpha-amylase activities, as well as plasma concentrations of IL-1beta and IL-6 have been markedly decreased, whereas plasma anti-inflammatory IL-10 concentration was significantly increased in these animals as compared to the control rats, subjected in the infancy to saline injection instead of LPS. Caerulein-induced fall in pancreatic SOD concentration was reversed and accompanied by significant reduction of MDA + 4 HNE in the pancreatic tissue. The effects of LPS derived from E. coli or S. typhi were similar. Pretreatment of suckling rats with LPS at dose of 10 mg/kg-day x 5 days resulted in the most prominent attenuation of acute pancreatitis at adult age, whereas LPS at dose of 5 mg/kg-day x 5 days given to the neonatal rats failed to affect significantly acute pancreatitis induced in these animals 2 months later. We conclude that: 1/ Prolonged exposition of suckling rats to bacterial endotoxin attenuated acute pancreatitis induced in these animals at adult age. 2/ This effect could be related to the increased concentration of antioxidative enzyme SO in the pancreatic tissue and to the modulation of cytokines production in these animals.

Influence of nutritional treatment on the postoperative course in patients with gastric cancer

PURPOSE

Malnutrition occurs in ca. 60% of all patients with gastric cancer. The obligatory standard for a curative radical oncological procedure is gastrectomy inclusive of regional lymph nodes. Nutritional treatment is expected to decrease possibilities of postoperative complications in patients subjected to curative surgery. The study is aimed at comparing treatment results in patients with gastric cancer subjected to radical surgery, nutritional and non-nutritional treatment respectively.

MATERIAL AND METHODS

The study included 176 patients qualified for curative surgery of a total or subtotal gastrectomy. Analysed were 2 groups of patients: group I--not subjected to nutritional treatment, group II--subjected to nutritional treatment, both in the circumoperative period. The groups were compared in respect to: 1) age, 2) sex, 3) nutritional condition, 4) degree of clinical cancer development, 5) histopathological cancer type, 6) kind of surgical procedure performed, 7) antibiotic and antithrombotic prevention. All complications observed in the patients were divided into four kinds: surgical of a high or low risk and general of a high or low risk.

RESULTS

Given the above-mentioned estimation parameters, no statistically significant differences between both groups were recorded. Of 176 patients, 27% showed surgical complications and 40% had general complications. No difference (p = 0.60) in the incidence of a high and low risk surgical complications between groups I and II in the circumoperative period was observed, a significant difference (p = 0.03) was recorded in the incidence of general complications. Low risk general complications (respiratory infections) were shown to occur significantly more often (p = 0.005) in patients receiving either parenteral or enteral nutrition after surgery.

CONCLUSIONS

A significant part of the patients with a medium degree and a medium to heavy degree of malnutrition subjected to a curative gastrectomy can pass through the postoperative period without using either parenteral or enteral nutrition and with no violations of all the other principles of the postoperative procedure as well as without provoking any significant increase of surgical complications. In case surgical complications should occur and delay resuming natural feeding, it is necessary that parenteral and/or enteral nutritional treatment be undertaken according to clinical circumstances and condition of the patient concerned; such proceedings increase chances of cure.

[The occurrence of the cleft lip and/or palate in cleft-twins]

Twin pregnancies are associated with an increased risk of congenital malformation, illness and higher incidence of newborns during labour. They are noticed to have been more frequent in Poland in recent years. Based on the hospital records we reviewed the most common facial anomaly in twins--the cleft lip and palate. The frequency of this malformation occurrence in Poland is 1:502 in newborns. The etiopathogenesis of this malformation, in 17-20%, results from genetic factors. Researches on the occurrence of cleft lip and palate in twins strongly confirm the heredity of the malformation.

THE AIM OF THE STUDY

The analysis of the occurrence frequency of the cleft lip and/or palate in cleft-twins was the main objective in our study.

MATERIAL AND METHODS

In the study of 21 sets of cleft-twins, 6 of them were monozygotic and 15 were dizygotic. It was assessed on the basis of data that was received from parents, same-sex twins and physical likeness. Twin-siblings who had cleft anomalies, always had cleft lip and palate or an isolated cleft palate.

RESULTS

The outcome showed that twins were not a subject to increased or decreased risk of cleft anomalies. Moreover, clefts did not increase the risk of twin-siblings labour. The hypothesis that a monozygotic twin pregnancy is a factor of increased risk of cleft anomaly was not confirmed. Presented data can be used in genetic counseling. In all likelihood, in the nearest future there will be chances for working out the cleft prophylaxis.

CONCLUSION

Twin pregnancy does not changes risk of cleft anomaly and its occurrence does not increase of twin-siblings labor.

Melatonin precursor; L-tryptophan protects the pancreas from development of acute pancreatitis through the central site of action

Melatonin, produced from L-tryptophan, protects the pancreas against acute damage by improving the antioxidative status of tissue. Melatonin receptors have been detected in the brain, but the contribution of these receptors to the pancreatic protection is unknown. The aim of our study was to compare the effects of melatonin precursor; L-tryptophan given intracerebroventricularly (i.c.v.) or intraperitoneally (i.p.) on the course of acute pancreatitis. Acute pancreatitis was induced by subcutaneous infusion of caerulein (5 microg/kg-h x 5 h). L-tryptophan was given i.p. (2.5, 25 or 250 mg/kg) or administered into right cerebral ventricle (0.02, 0.2 or 2.0 mg/rat) 30 min prior to the start of caerulein infusion. Plasma amylase, lipase and TNF alpha activities were measured to determine the severity of caerulein-induced pancreatitis (CIP). The lipid peroxidation products: malonylodialdehyde and 4-hydroksynonenal (MDA + 4-HNE) and activity of superoxide dismutase (SOD) were measured in the pancreas of intact or CIP rats with or without L-tryptophan pretreatment. Melatonin blood level was measured by RIA. CIP was confirmed by histological examination and manifested as an edema and rises of plasma levels of amylase, lipase and TNF alpha (by 550%, 1000% and 600%). MDA + 4-HNE was increased by 600%, whereas SOD activity was reduced by 75% in the pancreas of CIP rats. All manifestations of CIP were significantly reduced by pretreatment of the rats with L-tryptophan given i.c.v. at doses of 0.2 or 2.0 mg/rat, or by peripheral administration of this amino acid used at dose of 250 mg/kg i.p. In control rats plasma level of melatonin averaged about 40 +/- 2 pg/ml and was not significantly affected by CIP, by central application of L-tryptophan (0.02, 0.2 or 2.0 mg/rat) or by peripheral administration of this melatonin precursor used at doses of 2.5 or 25 mg/kg i.p. Plasma melatonin level was markedly increased by pretreatment of the rats with L-tryptophan given i.p. at dose of 250 mg/kg. We conclude that central administration of melatonin precursor; L-tryptophan, as well as peripheral application of high dose of this melatonin precursor prevented the pancreatic damage produced by CIP. The favorable effect of peripherally administered L-tryptophan could be related to the rise of melatonin plasma level and to pancreatoprotective action of this indoleamine. The beneficial effect of centrally administered L-tryptophan could be mediated through activation of central receptors for locally produced melatonin.

[Familial cleft lip with or without coexisting cleft palate]

Etiopatology of clefts has not been explained yet. It is assumed that the cause of this defect is complex and heterogeneous. Genes which induce the incidence of cleft have not been detected too but clinical observations indicate a familial predisposition. At the Plastic Surgery Clinic of the Łódz Medical Academy, on years 1972-2001, 3180 children with cleft lip or/and palate were being treated. The group under examination consisted of 540 children with positive family histories. Two genetic groups were confirmed and each of them with a different risk of the reoccurrence of the defect. The first group--cleft lip and palate, the second group--an isolated cleft palate. A correlation between the type of cleft and a child's sex and its cleft affected parent was found. Among children of mothers with cleft lip there were 60% of boys and only 15% of girls with the same type of cleft. In mothers with cleft lip and palate the same type of cleft has been detected in 70% of boys and 18% girls. Similar results were obtained when affected fathers were taken into account. However, in case of mothers and fathers who were affected with isolated cleft palate there were significantly more girls than boys who had cleft palate. An in-depth study of cleft inheritance mechanisms will make in the future a more precise prediction of the occurrence of the defect in consecutive generations possible. Perhaps, the chance to work out cleft preventions will emerge and the gathered data will be taken advantage of in genetic counselling.

Inhibition of jack bean urease by N-(n-butyl) thiophosphorictriamide and N-(n-butyl) phosphorictriamide: determination of the inhibition mechanism

N-(n-butyl)thiophosphorictriamide (NBPT) and its oxygen analogue N-(n-butyl)phosphorictriamide (NBPTO) were studied as inhibitors of jack bean urease. NBPTO was obtained by spontaneous conversion of NBPT into NBPTO. The conversion under laboratory conditions was slow and did not affect NBPT studies. The mechanisms of NBPT and NBPTO inhibition were determined by analysis of the reaction progress curves in the presence of different inhibitor concentrations. The obtained plots were time-dependent and characteristic of slow-binding inhibition. The effects of different concentration of NBPT and NBPTO on the initial and steady-state velocities as well as the apparent first-order velocity constants obeyed the relationships for a one-step enzyme-inhibitor interaction, qualified as mechanism A. The inhibition constants of urease by NBPT and NBPTO were found to be 0.15 microM and 2.1 nM, respectively. The inhibition constant for NBPT was also calculated by steady-state analysis and was found to be 0.13 microM. NBPTO was found to be a very strong inhibitor of urease in contrast to NBPT.

Effects of phenothiazine neuroleptics on the rate of caffeine demethylation and hydroxylation in the rat liver

The primary metabolic pathways of caffeine are 3-N-demethylation to paraxanthine (CYP1A2), 1-N-demethylation to theobromine and 7-N-demethylation to theophylline (CYP1A2 and other enzymes), and 8-hydroxylation to 1,3,7-trimethyluric acid (CYP3A). The aim of the present study was to investigate the influence of phenothiazine neuroleptics (chlorpromazine, levomepromazine, thioridazine, perazine) on cytochrome P-450 activity measured by caffeine oxidation in rat liver microsomes. The obtained results showed that all the investigated neuroleptics competitively inhibited caffeine oxidation in the rat liver, though their potency to inhibit particular metabolic pathways was not equal. Levomepromazine exerted the most potent inhibitory effect on caffeine oxidation pathways, the effect on 8-hydroxylation being the most pronounced. This indicates inhibition of CYP 1 A2 (inhibition of 3-N- and 1-N-demethylation; Ki = 36 and 32 microM, respectively), CYP3A2 (inhibition of 8-hydroxylations; Ki = 20 microM), and possibly other CYP isoenzymes (inhibition of 7-N-demethylation; Ki = 58 microM) by the neuroleptics. The potency of inhibition of caffeine oxidation by perazine was similar to levomepromazine. Thioridazine was a weaker inhibitor of caffeine 3-N- and 7-N-demethylation, while chlorpromazine was weaker in inhibiting caffeine 1-N- and 7-N-demethylation, compared to levomepromazine. In summary, the obtained results showed that all the investigated neuroleptics had a broad spectra of CYP inhibition in the rat liver. The isoenzymes CYP1A2 and CYP3A2 were distinctly inhibited by all the investigated neuroleptics, while other CYP isoenzymes (CYP2B and/or 2E1) by perazine and levomepromazine. The CYP3A2 inhibition was most pronounced. (Ki = 20-40 microM).

Speeds of invasion in a model with strong or weak Allee effects

We study an invasion model based on a reaction-diffusion equation with an Allee effect. We use a special, piecewise-linear, population growth rate. This function allows us to obtain traveling wave solutions and to compute wave speeds for a full range of Allee effects, including weak Allee effects. Some investigators claim that linearization fails to give the correct speed of invasion if there is an Allee effect. We show that the minimum speed for a sufficiently weak Allee may, in fact, be the same as that derived by means of linearization.

Involvement of cyclooxygenase-derived prostaglandin E2 and nitric oxide in the protection of rat pancreas afforded by low dose of lipopolysaccharide

Prostaglandins (PG), the products of arachidonate metabolism through cyclooxygenase (COX) pathway, protect the pancreas from the acute damage. The existence of two isoforms of COX was documented including: COX-1, present in normal tissues and COX-2, expressed at the site of inflammation, such as induced by bacterial lipopolysaccharide (LPS). Pretreatment with low dose of LPS and activation of nitric oxide (NO) synthase (NOS) has been shown to prevent the injury caused by caerulein-induced pancreatitis (CIP) in the rat. The aim of this study was to investigate the role of COX-1 and COX-2 in the LPS-induced protection of the pancreas against CIP and the involvement of NOS in the activation of COX-PG system in the rats with CIP. CIP was produced by subcutaneous (s.c.) infusion of caerulein (5 microg/kg-h for 5 h) to the conscious rats. Protective dose of LPS, from Escherichia coli, (1 mg/kg) was given intraperitoneally (i.p.) 15 min prior to the start of CIP. Nonselective inhibitor of COX; indomethacin (5 or 10 mg/kg), selective inhibitor of COX-1: resveratrol, or a highly selective inhibitors of COX-2: rofecoxib or NS-398 (2 or 10 mg/kg) were injected i.p. 15 min prior to the administration of LPS. COX-1 or COX-2 mRNA was determined by reverse transcription-polimerase chain reaction (RT-PCR) in the pancreatic tissue. Pancreatic blood flow (PBF) was measured by a laser Doppler flowmetry. PGE2 content in the pancreas was measured by radioimmunoassay. CIP was manifested by an increase of pancreatic weight and plasma amylase activity (by 500% and 700%, respectively) and it was confirmed by histological examination. CIP slightly increased pancreatic PGE2 generation (by 12%) and diminished PBF (by about 40%). LPS (1 mg/kg i.p.), given prior to the start of CIP, increased PGE2 generation in the pancreas (by 45%), reversed the histological manifestations of pancreatitis, reduced the rise in amylase blood level and improved PBF. Administration of nonselective inhibitor of COX; indomethacin (5 or 10 mg/kg i.p.) prior to the injection of LPS abolished its protective effects on CIP and reduced pancreatic PGE2 generation. Selective inhibitor of COX-1; resveratrol (10 mg/kg i.p.) given prior to the injection of LPS reversed its protective effects against CIP. Pretreatment with a selective inhibitors of COX-2: rofecoxib or NS-398 (10 mg/kg) attenuated LPS-induced pancreatic protection in the CIP rats. COX-1 expression was detected in the intact pancreas and was not significantly changed by CIP, LPS, indomethacin, NS-389 and their combination, while COX-2 mRNA expression appeared in the pancreas of ratssubjected to CIP and was significantly increased after LPS injection to these rats. Addition of selective COX-2 inhibitor; NS-389, or nonselective inhibitor of COX; indomethacin, enhanced COX-2 mRNA expression in the rats with CIP pretreated with LPS. Pretreatment of the rats with inhibitor of NOS; L-NNA (20 mg/kg i.p.), given together with LPS, 15 min prior to the start of caerulein overstimulation, resulted in complete reversion of LPS-induced pancreatic protection and decreased PGE2 generation stimulated by LPS. Addition to L-NNA of the substrate for NOS; L-arginine (100 mg/kg i.p.), restored pancreatic protection afforded by low dose of LPS and increased pancreatic PGE2 level in the rats with CIP. We conclude that: 1. increased pancreatic PGE2 generation, induced by low dose LPS pretreatment, contributes to the pancreatic resistance to acute damage produced by caerulein overstimulation and 2. the NO-system is involved in above stimulation of PGE2 generation and pancreatic protection against acute damage.

Invasion speeds in fluctuating environments

Biological invasions are increasingly frequent and have dramatic ecological and economic consequences. A key to coping with invasive species is our ability to predict their rates of spread. Traditional models of biological invasions assume that the environment is temporally constant. We examine the consequences for invasion speed of periodic and stochastic fluctuations in population growth rates and in dispersal distributions.

The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro

BACKGROUND

Recent studies clearly demonstrate that Helicobacter pylori (H. pylori) infection of the stomach causes persistent elevation of ammonia (NH3) in gastric juice leading to hypergastrinemia and enhanced pancreatic enzyme secretion.

METHODS

The aim of this study is to evaluate the influence of NH4OH on plasma gastrin level and exocrine pancreatic secretion in vivo in conscious dogs equipped with chronic pancreatic fistulas and on secretory activity of in vitro isolated acini obtained from the rat pancreas by collagenase digestion. The effects of NH4OH on amylase release from pancreatic acini were compared with those produced by simple alkalization of these acini with NaOH.

RESULTS

NH4OH given intraduodenally (i.d.) in increasing concentrations (0.5, 1.0, 2.0, 4.0, or 8.0 mM/L) resulted in an increase of pancreatic protein output, reaching respectively 9%, 10%, 19%, 16% and 17% of caerulein maximum in these animals and in a marked increase in plasma gastrin level. NH4OH (8 x 0 mM/L, i.d.) given during intravenous (i.v.) infusion of secretin (50 pmol/kg-h) and cholecystokinin (50 pmol/kg-h) reduced the HCO3 and protein outputs by 35% and 37% respectively, as compared to control obtained with infusion of secretin plus cholecystokinin alone. When pancreatic secretion was stimulated by ordinary feeding the same amount of NH4OH administered i.d. decreased the HCO3- and protein responses by 78% and 47% respectively, and had no significant effect on postprandial plasma gastrin. In isolated pancreatic acini, increasing concentrations of NH4OH (10(-7)-10(-4) M) produced a concentration-dependent stimulation of amylase release, reaching about 43% of caerulein-induced maximum. When various concentrations of NH4OH were added to submaximal concentration of caerulein (10(-12) M) or urecholine (10(-5) M), the enzyme secretion was reduced at a dose 10(-5) M of NH4OH by 38% or 40%, respectively. Simple alkalization with NaOH of the incubation medium up to pH 8.5 markedly stimulated basal amylase secretion from isolated pancreatic acini, whereas the secretory response of these acini to pancreatic secretagogues was significantly diminished by about 30%. LDH release into the incubation medium was not significantly changed in all tests indicating that NH4OH did not produce any apparent damage of pancreatic acini and this was confirmed by histological examination of these acini.

CONCLUSIONS

1. NH4OH affects basal and stimulated pancreatic secretion. 2. The excessive release of gastrin may be responsible for the stimulation of basal pancreatic enzyme secretion in conscious animals, and 3. The inhibitory effects of NH4OH on stimulated secretion might be mediated, at least in part, by its direct action on the isolated pancreatic acini possibly due to the alkalization of these acini.

Rate estimation for a simple movement model

This paper introduces a simple stochastic model for waterfowl movement. After outlining the properties of the model, we focus on parameter estimation. We compare three standard least squares estimation procedures with maximum likelihood (ML) estimates using Monte Carlo simulations. For our model, little is gained by incorporating information about the covariance structure of the process into least squares estimation. In fact, misspecifying the covariance produces worse estimates than ignoring heteroscedasticity and autocorrelation. We also develop a modified least squares procedure that performs as well as ML. We then apply the five estimators to field data and show that differences in the statistical properties of the estimators can greatly affect our interpretation of the data. We conclude by highlighting the effects of density on per capita movement rates.

Protective role of endogenous nitric oxide (NO) in lipopolysaccharide--induced pancreatic damage (a new experimental model of acute pancreatitis)

Lipopolysaccharide (LPS) derived from the bacterial cell wall activates the inflammatory response in the tissue but the role of LPS in the pathogenesis of pancreatic damage and in the activation of NO system in the pancreas has not been fully explained. The aim of this study was to investigate the effect of repeated administration of LPS to the rats on the integrity of the pancreas, on the ability of isolated pancreatic acini to secrete the amylase and on the plasma level of tumor necrosis factor alpha (TNFalpha). The role of NO in the pancreatic resistance to the damage was assessed in animals subjected to repeated administration of LPS. To induce pancreatic damage one group of rats received intraperitoneal (i.p.) injection of LPS (from E. coli) every day during 5 consecutive days (10 mg/kg--day). Another groups of animals were given N(G)-nitro-L-arginine (L-NNA), an inhibitor of NO synthase (NOS) (20 mg/kg i.p.) alone or in combination with L-arginine (100 mg/kg i.p.), 30 min prior to each LPS injection. Plasma level of TNFalpha was determined by ELISA kit. Repeated administration of LPS produced mild pancreatic inflammation that was most pronounced at day 5 of LPS treatment and manifested as edema, neutrophil infiltration and hemorrhage of the pancreas. The survival rate after 5 days treatment with LPS was 87.5%. Pancreatic weight, plasma levels of TNFalpha and amylase, pancreatic blood flow (PBF) and NO generation by pancreatic acini were markedly increased in rats subjected to repeated administration of LPS whereas the amylase response of isolated pancreatic acini to pancreatic secretagogues was significantly attenuated. Suppression of NOS by L-NNA resulted in a dramatic increase in the mortality of the animals reaching 50% and significantly increased inflammatory changes in the pancreatic tissue, decreased PBF, abolished the ability of pancreatic acini to release NO and to secrete amylase. Pancreatic weight and plasma levels of amylase and TNFalpha significantly increased in the group of rats treated with combination of LPS+L-NNA as compared to the animals received LPS alone. Addition of L-arginine to L-NNA+LPS administration reversed all harmful effects produced by L-NNA in the pancreas. We conclude that repeated administration of high doses of bacterial LPS to the rats could induce pancreatic tissue damage by itself, however, it is not able to produce severe pancreatitis. Suppression of NO generation significantly aggravates the pancreatic lesion produced by LPS leading to the dramatic mortality in treated rats. The rise of plasma level of TNFalpha corresponds to the severity of pancreatic inflammation.

[Evaluation of internal nose deformation in patients with unilateral cleft lip and palate]

The methods of assessment of nose deformation in patients with unilateral cleft lip and palate have been presented. The study covered 45 patients with clefts, of 14-20 years of age who had undergone the infant surgery, and 45 patients at the same age serving as controls. The condition of nasal septum has been clinically examined in both groups and the nasal resistance has been measured by means of front and rear rhinomanometry. In the cleft group 80% of patients presented their cartilaginous septum deviated to the non-cleft side, and 85% had their bony septum deviated to the cleft side. In the cleft group, the front rhinomanometry revealed significantly higher resistance on the cleft side than on the non-cleft side and in controls. The rear rhinomanometry showed no significant differences in both groups, except the patients with clefts, who had been submitted to surgery with pharyngeal flap, in whom higher values of resistance had been found.

Inflammatory pseudotumor of the liver treated surgically

This report describes the case of an inflammatory pseudotumor of the liver in a 61 year-old female, diagnosed by an ultrasound scan (USG), computed tomography (CT) and needle biopsy. The right hemihepatectomy has been carried out. There were no complications in the post-operative course.

[Selection of patient age for evaluation of treatment results in cleft lip and palate]

The results of the complex treatment of 125 patients with unilateral and bilateral lip and palate cleft, aged 3-5, 10-12 and 14-18 years, were evaluated by analysis of medical documentation. The study showed that the results of lip, vestibule and palate reconstruction and speech can be evaluated already at 12 years of age. However, final esthetic and functional assessment of the nose and maxillo-occlusional conditions is indicated after 14 years of age, best between 18-20 years.

[Assessment of long-term results in cleft lip and palate]

The study concerned 230 patients (175 UCLP and 55 BCLP) aged 14-20, who had been treated in the years 1972-82 in accordance with the Centre for Congenital Defects programme, at the Department of Plastic Surgery, Medical University of Lódź. The follow-up comprised: aesthetic and functional assessment of the lip, upper vestibule and nose as well as evaluation of occlusion and speech abilities (intelligibility, articulation, nasality). The assessment of lip and vestibule gave good and acceptable results in 97% of UCLP patients and in 89% of BCLP. The external nose appeared aesthetically and functionally good in 67% of UCLP and in 94% of BCLP. The defects of occlusion, mainly various forms of cross-bite, were found in 48% of UCLP, who had undergone orthodontic treatment. The maxillo-occlusal defects with no prior orthodontics were found in 63% of UCLP. Alike the defects of occlusion in untreated BCLP were most frequent. The intelligibility and articulation of speech were significantly better in patients who had undertaken the postoperational speech therapy (95%:75%). The assessment in general presented better results in UCLP patients, who had been submitted not only to surgery but also took up orthodontic treatment and speech therapy.

[Prevention and principles of management in case of cardiac tamponade after catheterisation of the subclavian vein in parenteral nutrition]

The authors described different complications after the subclavian vein catheterisation, focusing on the cardiac tamponade. The authors presented the prevention and treatment principles respectively in case of the cardiac tamponade and reported experiences in this field.

The enthalpimetric determination of inhibition constants for the inhibition of urease by acetohydroxamic acid

The effect of concentration of acetohydroxamic acid (AHA) on inhibition of jack bean urease in phosphate buffer, pH 7.0, at 25 degrees C, was studied. The measurements were performed at urease concentration of 2.5 mg/100 cm3 for concentrations of urea and AHA ranging in the range of 2-50 mmol dm-3 and 0.25-10 mmol dm-3, respectively. The reactions were monitored by two techniques: analytical and enthalpimetric. For the analytical technique the growth of ammonia concentration in the course of the reaction was determined. From the recorded progress curves the following parameters were calculated for each inhibitor concentration: the initial reaction rate, the steady-state rate and the inversion constant. From these parameters the inhibition constants of the initial and steady-state stages of the reaction, Ki and Ki, were calculated. The former constant did not change whereas the latter one proved to decrease quickly with an increase in inhibitor concentration. This behaviour resulted from the fact that the inactive complex EI was not a product of internal inversion but was formed in the reaction: 2/3I + EI-->(EI.2/3I). The dissociation constant of this complex is equal to about 0.3 x 10(-3) (mol dm-3)2/3.

The enthalpimetric determination of inhibition constants for the inhibition of urease by acetohydroxamic acid

The effect of concentration of acetohydroxamic acid (AHA) on inhibition of jack bean urease in phosphate buffer, pH 7.0, at 25 degrees C, was studied. The measurements were performed at urease concentration of 2.5 mg/100 cm3 for concentrations of urea and AHA ranging in the range of 2-50 mmol dm-3 and 0.25-10 mmol dm-3, respectively. The reactions were monitored by two techniques: analytical and enthalpimetric. For the analytical technique the growth of ammonia concentration in the course of the reaction was determined. From the recorded progress curves the following parameters were calculated for each inhibitor concentration: the initial reaction rate, the steady-state rate and the inversion constant. From these parameters the inhibition constants of the initial and steady-state stages of the reaction, Ki and Ki, were calculated. The former constant did not change whereas the latter one proved to decrease quickly with an increase in inhibitor concentration. This behaviour resulted from the fact that the inactive complex EI was not a product of internal inversion but was formed in the reaction: 2/3I + EI-->(EI.2/3I). The dissociation constant of this complex is equal to about 0.3 x 10(-3) (mol dm-3)2/3.

Genetic control of sex-chromosome inactivation during male meiosis

During meiotic prophase in male mammals, the sex chromosomes are transcriptionally inactivated and form a condensed chromatin domain known as the sex body. It is not known how the assumption of this chromatin configuration is determined and regulated. We used various genetic models to test whether a complete sex-chromosome pair, effective sex-chromosome pairing, or an intact X chromosome is required for sex-body formation or transcription inactivation. The sex chromosome aberrations studied did not interfere with sex-body formation, and there is no evidence for inactivation failure or reactivation of the aberrant sex chromosomes. The results of this study suggest that control of sex-body formation is not intrinsic to the sex chromosomes and thus may be at the level of the testis.