Splenic injury as a rare complication of colonoscopy.

Injury resulting from colonoscopy is rare. Bleeding and perforation are the most serious complications. The case history is described of a patient who developed splenic rupture following screening colonoscopy with associated polypectomy.

The metabolic impact of extracellular nitrite on aerobic metabolism of Paracoccus denitrificans.

Nitrite, in equilibrium with free nitrous acid (FNA), can inhibit both aerobic and anaerobic growth of microbial communities through bactericidal activities that have considerable potential for control of microbial growth in a range of water systems. There has been much focus on the effect of nitrite/FNA on anaerobic metabolism and so, to enhance understanding of the metabolic impact of nitrite/FNA on aerobic metabolism, a study was undertaken with a model denitrifying bacterium Paracoccus denitrificans PD1222. Extracellular nitrite inhibits aerobic growth of P. denitrificans in a pH-dependent manner that is likely to be a result of both nitrite and free nitrous acid (pKa = 3.25) and subsequent reactive nitrogen oxides generated from the intracellular passage of FNA into P. denitrificans. Increased expression of a gene encoding a flavohemoglobin protein (Fhp) (Pden_1689) was observed in response to extracellular nitrite. Construction and analysis of a deletion mutant established Fhp to be involved in endowing nitrite/FNA resistance at high extracellular nitrite concentrations. Global transcriptional analysis confirmed nitrite-dependent expression of fhp and indicated that P. denitrificans expressed a number of stress response systems associated with protein, DNA and lipid repair. It is therefore suggested that nitrite causes a pH-dependent stress response that is due to the production of associated reactive nitrogen species, such as nitric oxide from the internalisation of FNA.

Influence of rheological behaviour of particulate/polymer dispersions on liquid-filling characteristics for hard gelatin capsules.

Lactose/poloxamer dispersions were prepared by mixing under vacuum to achieve a de-aerated mix with good capsule filling properties and disperse phase uniformity at 70 degrees C. Satisfactory capsule filling of molten dispersions was achieved up to a limiting concentration of disperse phase, dependent on particle size distribution and continuous phase viscosity. Lactose/poloxamer dispersions exhibited thixotropic shear thinning behaviour with an abrupt increase in apparent viscosity above a limiting concentration of disperse phase. There was a good correlation between satisfactory filling of molten dispersions into capsules and apparent viscosity of the formulation, whereas, the pronounced increase in apparent viscosity resulted in unsatisfactory filling above a critical concentration of disperse phase. The rheological data was analysed in detail using empirical models and also used to identify capsule filling problems at extrudate shear rates for flow from hopper to pump (12 s(-1)) and from nozzle to capsule (340 s(-1)).

Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria: Physiology and Regulatory Mechanisms.

Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nitric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the application of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural efficiency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understanding of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation.

Action of beta-galactosidase on novel synthetic macromolecular substrates. A processive enzymic reaction controlled by coulombic interactions.

Macromolecular beta-galactosidase substrates were prepared by attaching o-nitrophenyl-beta-galactoside to carboxymethyldextran with positively charged linking groups. Almost all of the substituents were susceptible to enzymic hydrolysis by two distinct pathways. Under some conditions, there was random reaction to give a soluble product. In other conditions, in the initial stages of the reaction, most of the substituents of some, but not all, of the substrate polymers were hydrolyzed to give a product which precipitated as a second aqueous phase. Kinetics of hydrolysis were studied with respect to charge and molecular weight of both the enzyme and substrate. Factors that caused a decrease in Km favored formation of the second phase product. The reaction has similarities to the processive catalytic reactions found in naturally occurring enzyme systems with polymeric charged substrates.

First report on UK database of haemophilia B mutations and pedigrees. UK Haemophilia Centres.

In order to obtain complete success in the carrier and prenatal diagnoses required for genetic counselling in haemophilia B a new strategy is being implemented in the UK. This entails the construction of a national confidential database of mutations, pedigrees and haematological data. This will allow the inefficient indirect tests based on the analysis of DNA polymorphisms to be abandoned and direct detection of the gene defect to be used instead. After two and a half years of nationwide collaboration, 702 samples have been collected from 313 families, representing more than half of the UK haemophilia B families, and 217 mutations have been characterised. The 141 diagnostic tests so far performed have clearly indicated that the new strategy not only allows virtually 100% diagnostic success, but also rapid results. This work on haemophilia B may represent a model for other diseases with high mutational heterogeneity.

Determination of hprt mutant and mutation frequencies and the molecular characterization of human derived in vivo T-lymphocyte mutants.

Using a T-lymphocyte clonal assay, 73 6-thioguanine resistant T-lymphocytes were isolated from two blood samples obtained 4 months apart from a 50-year-old male subject. Sixty-six of these mutants were characterized at the DNA sequence level using cDNA. One particular single base substitution was recovered a total of 23 times. The majority of T-cell receptors (TCR) of these mutants all share a common gamma-TCR rearrangement, and thus likely represent a single mutational event that underwent clonal expansion in vivo. Siblings of this clone were recovered in both collections. Three other single base substitutions were also recovered more than once. In two of the three cases, the mutants were also found to be clonally related, while in one case they were not. A number of identical exon loss events were also recovered, yet none of these were clonally related. This probably reflects the multiple pathways by which these mutations can arise. The TCR data was used to correct the observed mutant frequency to produce an estimate of the actual mutation frequency. The two mutant frequencies, 18 x 10(-6) and 19 x 10(-6), obtained from the first and second sampling periods, respectively, can thus be corrected to yield true mutation frequency's of 12 x 10(-6) each.

Molecular analysis of mutations in the hprt gene in circulating lymphocytes from normal and DNA-repair-deficient donors.

Circulating lymphocytes from patients with the DNA-repair-deficient disorders, xeroderma pigmentosum (XP) and ataxia telangiectasia (A-T) have elevated frequencies of mutants at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus. We have analysed the DNA sequence of the hprt gene in mutants from normal donors, and compared them with mutants from XP and A-T individuals. In normal donors we found a range of mutations including principally transitions (40%), transversions (32%) and small deletions (20%). In an excision-deficient XP donor from complementation group C the mutation spectrum was similar to that from normal donors, whereas in an XP variant there was a significantly higher frequency (44%) of small deletions. In the two A-T donors, there was a high frequency of large deletions (22 and 75%) compared with only 4% in normal donors.

Quantifying electrostatic interactions in pharmaceutical solid systems.

Triboelectrification of pharmaceutical powders with stainless steel and polymer contact surfaces was investigated. alpha-Lactose monohydrate, from 90 to 125 up to 355-500 microm, was used to quantify electrostatic interactions with negligible powder adhesion to the contact surface. Size fractions down to 53-75 microm alone and in binary mixtures with <10 microm lactose or micronized salbutamol were used to investigate triboelectrification with powder adhered to the contact surface. Triboelectrification was performed in a cyclone charger fitted with interchangeable contact surfaces of steel and polymers, representing the surfaces of pharmaceutical processing and manufacturing equipment, packaging materials and components of dry powder inhaler devices. The results for single component powders showed charge acquisition was inversely related to particle size, where contact surface contamination was negligible. However, with particulate contamination, triboelectrification was more complex due to particle collisions with clean and contaminated contact surfaces. Analysis of adhered and non-adhered powder provided information about changes in composition of two component powders during triboelectrification. Particle size and chemical analyses showed that composition changes of mixtures may be related to powder/contact surface affinity and interparticulate forces for separation of components in a cohesive mix during triboelectrification.

Comparison of surface modification and solid dispersion techniques for drug dissolution.

Surface modification and solid dispersion formulations using hydrophilic excipients can significantly alter the dissolution behaviour of hydrophobic drug materials. The effect of these techniques used individually and in combination on the dissolution properties of the hydrophobic drug, phenylbutazone (PB), are compared. PB was treated with a poloxamer, Synperonic((R)) F127 by an adsorption method. Solid dispersions (10 and 20% w/w) were prepared with untreated PB or PB previously modified with Synperonic((R)) F127 (PBT) in molten F127. Dissolution tests of capsule formulations of PB, PBT and solid dispersion formulations, in pH 6.4 buffer at 37+/-0.5 degrees C demonstrated that after 140 min, release of PB was 16.7%, but 71.4% from the solid dispersion, whereas from the PBT formulation 85.6% was released. The Synperonic((R)) F127 content of PBT was only 0.05% of that in the solid dispersion formulation which suggests that it is the nature of the drug polymer contact rather than the amount of polymer which is more critical in influencing dissolution behaviour. Comparison of PBT and the 10% w/w solid dispersion of PBT in F127 showed similar amounts of drug in solution after 140 min. However there was a significantly higher release rate for PBT. Both formulation techniques offer significant improvements in drug release over untreated PB, and a combination of techniques changes the rate but not the extent of release in comparison with the surface modification technique alone.

Effect of contamination of pharmaceutical equipment on powder triboelectrification.

Triboelectrification of pharmaceutical powders may cause problems during processing and manufacture due to adhesion/cohesion effects. The aim of this work was to investigate the role of adhered particles and moisture as contact surface contaminants on the electrostatic charging of size fractionated lactose, following contact with a surface, i.e. stainless steel, typically used in pharmaceutical process and manufacturing operations. Replicated experimental runs without cleaning the contact surface showed a successive decrease in the net electronegative charge due to adhered lactose particles. Removal of these contaminating particles by different cleaning methods had a considerable effect on the charge after triboelectrification. The charge on the lactose samples was found to decrease when humidity in the cyclone apparatus was increased from 2 to 100% relative humidity. These results clearly demonstrate that moisture, particulate contamination and method of cleaning of processing equipment during pharmaceutical manufacturing operations may influence the electrostatic behaviour of powders.

Surface modification and electrostatic charge of polystyrene particles.

Particle surface modification by poloxamer adsorption can significantly alter the electrostatic charge, adhesion behaviour and consequently handling properties of a material. The charge reduction on polystyrene spheres achieved by this modification technique is dependent on the concentration, molecular weight and conformation of poloxamer at the particle surface. Adsorption isotherms of poloxamers on polystyrene particles follow a Langmuir profile and there is an apparent correlation between the extent of adsorption and ability of poloxamer to reduce electrostatic charge. Surface analysis techniques, X-ray photoelectron spectroscopy and Time of Flight Secondary Ion Mass Spectrometry have generated data on the thickness of the adsorbed poloxamer layer and provided evidence to suggest that the polypropylene oxide component of the poloxamer adsorbs to the polystyrene surface and there is a polyethylene oxide rich outer surface which may influence the charge alteration.

Triboelectrification of spray-dried lactose prepared from different feedstock concentrations.

Powder systems may acquire electrostatic charge during various pharmaceutical processing operations and may give rise to difficulties in handling and powder flow, mainly due to adhesion/cohesion effects. We have investigated the electrostatic charging of spray-dried lactose prepared from different feedstock concentrations using a laboratory spray-dryer. Triboelectrification of the spray-dried lactose samples was effected through contact with the stainless steel surface of either a mixing vessel or a cyclone separator. Results from both techniques showed differences in charge accumulation and particle-steel adhesion between the spray-dried lactose samples. As the feedstock concentration used to produce the spray-dried lactose was increased in the range 10-50% w/v, the mean charge on the lactose decreased from -20.8 to -1.3 nC g(-1) and -54.9 to -4.1 nC g(-1) for the mixing vessel and cyclone separator, respectively, with a corresponding decrease in adhesion. In addition, as the feedstock concentration was increased from 10 to 50% w/v, decreases were obtained in surface area values (1.06 to 0.56 m2 g(-1)), pore diameter (198.7 to 83.5 microm) and pore volume (1.09 to 0.75 cm3 g(-1)), and together with differences in crystal form correlated with the charge and adhesion results. The results suggested that the feedstock concentration could have a considerable influence on the charging and adhesional properties of spray-dried lactose. This may have relevance during pharmaceutical processing and manufacturing operations.

Protein, glycogen, and water content in schistosomes.

The volume of distribution (= VD) of water was measured in Schistosoma mansoni, S. haematobium, S. japonicum, and Hymenolepis diminuta. In the rat tapeworm, H. diminuta, the volume of distribution of 3H-water was positively correlated with wet weight (r = 0.87, P less than 0.001) and this same phenomenon also was demonstrated in S. mansoni (r = 0.90, P less than 0.001). The 5-sec VDwater was constant over a range of glucose (0.01-50 mM) and phenylalanine (0.01-20 mM) concentrations in both male and female schistosomes. The VD of antipyrine, which permeates by virtue of its lipophilic properties, also was shown to correlate with protein content in S. mansoni. Protein content determined in single, isolated schistosomes was correlated with the volume of distribution of water in S. haematobium, S. japonicum, and S. mansoni males and females. Age-related variations in the protein content (of S. mansoni) and volume of distribution of water (in both S. japonicum and S. mansoni) were also defined, and the use of tritiated water content as an indicator of mass in small tissue samples was thus established. Female blood flukes recovered from mice infected for more than 90 days appeared to be characterized by a slight reduction in size with age. Schistosoma mansoni reared in the golden hamster may be slightly smaller than schistosomes of the same strain raised in outbred mice. These results provide a baseline that should be useful for future physiological and immunological studies.

Quantitation of hyaluronic acid in equine synovia.

An assay for the determination of hyaluronic acid concentration in equine synovia (synovial fluid) was investigated. The method involved the degradation of hyaluronic acid, using a highly specific microbial enzyme. The unsaturated tetra- and hexasaccharide products were oxidized with periodate and caused to react with thiobarbituric acid for form a chromophore which absorbed in the visible range of the spectrum. The method was precise within acceptable limits for synovia and compared favorably with the widely used carbazole method of Bitter and Muir (Anal Biochem 4:330-334, 1962). The between-assay coefficient of variation was 1.7% and the method was found to be linear to 100 microgram of hyaluronic acid. The mean value for hyaluronic acid concentration in synovia of health horses was 127 mg/100 ml.

Hyaluronic acid concentration in synovial fluid from normal and arthritic joints of horses.

A method previously described was used to determine the hyaluronic acid concentration in synovia from normal and arthritic horse joints. The concentration of hyaluronic acid in the synovia from arthritic joints was found to be significantly lower than the concentration in fluid from normal joints.

Changes in the synovia after the intra-articular injection of sodium hyaluronate into normal horse joints and after arthrotomy and experimental cartilage damage.

Sodium hyaluronate was injected into normal horse joints and joints that had undergone an arthrotomy and experimental cartilage damage. The elimination half-life for hyaluronic acid in normal joints was found to be approximately 96 h. The injection caused a non-significant increase (42%) in synovial fluid protein concentration and a fall in the intrinsic viscosity of the fluid. In the arthrotomy group the synovial fluid hyaluronic acid concentration fell after surgery but it was unaffected by the injection of sodium hyaluronate. An initial rise in the intrinsic viscosity of the synovial fluid from the arthrotomy group coincided with an increase in protein concentration. However there was no significant difference between the mean intrinsic viscosity or protein concentration in synovia from the control and treated joints at any time after surgery.

Locus of control of smokers, nonsmokers, and nonpracticing smokers.

In this survey, score analyses of 123 male and female respondents, ages 21 to 33 years, yielded no significant differences between either sex and smokers versus nonsmokers on Rotter's locus of control scale. Of particular interest was that nonpracticing smokers (quitters) scored more internal than either smokers or nonsmokers.

The contribution of nurses' perceptions and actions in defining scope and stabilising professional boundaries of nursing practice.

This paper reports on the findings of a naturalistic inquiry study that explored the scope and boundaries of nursing practice. Findings from interview and observation data suggest that nurses negotiate and adjust professional boundaries on an individual, case-by-case basis, thereby managing the scope of their practice as they see it in that circumstance. The strategies they used are presented in four major categories: 1) maintaining a comfort zone, 2) expanding into safe territory, 3) moving into the grey zone and 4) stepping over the line. Findings show that nurses' efforts to maintain the comfort zone serve to perpetuate the status quo and may threaten holistic care. Expanding nursing actions to include functional roles such as coordinating care, sharing information, advocating (for patients), collaborating and innovating offers the profession critical building blocks for defining the scope of nursing practice. Clarifying the grey zone (or overlapping territory) is an essential task for the profession in determining the boundaries of nursing practice. The data revealed that, partly due to the ambiguity of the grey zone, nurses may step over the line into medical decision-making and outside the legal sanctions for the professional nursing role. The implications of this study highlight the need for nursing to define its scope of practice and in so doing stabilise professional boundaries.