Investigation of diarrhoea in critically ill patients receiving enteral nutrition

The incidence and causes of diarrhoea among critically ill patients receiving enteral tube feeding were investigated. Sixty acutely ill surgical or medical intensive care patients who had had a minimum of 48 hrs bowel rest were entered into the study. They were randomly assigned to receive one of two lactose free liquid formula diets - "Ensure", a commercially available feed containing 825 kCal/L and 34 g/L of protein with an osmolality of 441mOsm/1 or "Casilan Oil", a home-made feed containing 840 kCal /L and 45g/L of protein with an osmolality of 383 mOsm/1. The feeds were administered by constant nasogastric infusion. Patients received 1000ml at a rate of 40ml per hour for the first day and up to 2000ml at 80 ml per hour for the remainder of the study period. Investigations included documentation of medical history, medications administered and clinical details for each patient. Serum albumin was measured and the nutritional status of each patient was assessed using anthropometric measurements. Feeds were tested for bacterial contamination on the three days following the start of feeding and small intestinal bacterial overgrowth was assessed by the 1 g-¹⁴C Xylose breath test of Toskes and King. Twelve of the sixty patients had to be withdrawn from the trial within 24 hours of the start of enteral feeding for medical reasons. The remaining forty eight patients completed at least three days on enteral feeding and thereby became eligible for analysis. In 10/48 patients (21%) diarrhoea was present before enteral feeding began. Four of these 1 O patients continued to pass loose stools when enteral feeding was started while the remaining 6 settled. Diarrhoea developed in a further 10 patients (21%) after enteral feeding began. The overall incidence of diarrhoea in the group of critically ill patients studied was therefore 42% (20/48). However, of the fourteen patients who experienced diarrhoea during enteral feeding four had diarrhoea before feeding began. Therefore, the true incidence of diarrhoea related to enteral feeding was only 10/38 (26%). Furthermore, in 7 of these 10 patients, another possible cause of diarrhoea was present. There was no significant association between diarrhoea and nutritional status, hypoalbuminaemia, sepsis, length of bowel rest, sucralfate and antibiotic therapy other than amikacin. Twenty one patients received Ensure and 27 received Casilan Oil. Despite the differences in the composition of the feeds, the incidence of diarrhoea was similar on the Ensure and the Casilan Oil. No particular factor pertaining to the composition of the feeds was associated with diarrhoea. Significant contamination of feeds was universal but there was no constant relationship between bacterial counts, or types, and the occurrence of diarrhoea. Certain other factors were found to be significantly associated with diarrhoea. Abdominal injury was positively associated with the occurrence of diarrhoea (p<0.05). Diarrhoea could have been attributed to the underlying disease state in 7 of the patients. All three patients who were receiving lactulose as treatment for liver failure developed diarrhoea. While no association was noted between diarrhoea and antibiotic therapy in general, treatment with the antibiotic, amikacin, correlated significantly, albeit marginally, with the occurrence of diarrhoea (p<0.05). Twenty six patients were tested for small intestinal bacterial overgrowth. Only one patient, with an elevated excretion of ¹⁴CO₂, indicative of small intestinal bacterial overgrowth, developed diarrhoea. There was, however, a positive association between diarrhoea and decreased excretion of ¹⁴CO₂. It would appear that the bacterial flora was suppressed in patients with diarrhoea. Amikacin therapy was also associated with decreased excretion of ¹⁴CO₂. This may suggest that amikacin could have altered the bowel flora with resultant development of diarrhoea. While abdominal injury and disease were associated with the development of diarrhoea and amikacin was a possible factor associated with diarrhoea, the results of the present study indicate that enteral tube feeding with either the commercial feed, Ensure or the home-made feed, Casilan Oil was not a cause of diarrhoea in the majority of critically ill patients assessed. Furthermore, in most patients who commenced the trial with diarrhoea, improvement was noted on enteral feeding

Energy-momentum conservation in pre-metric electrodynamics with magnetic charges

A necessary and sufficient condition for energy-momentum conservation is proved within a topological, pre-metric approach to classical electrodynamics including magnetic as well as electric charges. The extended Lorentz force, consisting of mutual actions by F=(E, B) on the electric current and G=(H, D) on the magnetic current, can be derived from an energy-momentum "potential" if and only if the constitutive relation G=G(F) satisfies a certain vanishing condition. The electric-magnetic reciprocity introduced by Hehl and Obukhov is seen to define a complex structure on the tensor product of 2-form pairs (F,G) which is independent of but consistent with the Hodge star operator defined by any Lorentzian metric. Contrary to a recent claim in the literature, it does not define a complex structure on the space of 2-forms itself.Comment: 8 pages, 1 fugur

Prolonged Fever, Hepatosplenomegaly, and Pancytopenia in a 46-Year-Old Woman

Liran Levy and colleagues discuss the differential diagnosis, investigation, and management of a 46-year-old woman with fever, weakness, night sweats, and weight loss

Invariant and polynomial identities for higher rank matrices

We exhibit explicit expressions, in terms of components, of discriminants, determinants, characteristic polynomials and polynomial identities for matrices of higher rank. We define permutation tensors and in term of them we construct discriminants and the determinant as the discriminant of order $d$, where $d$ is the dimension of the matrix. The characteristic polynomials and the Cayley--Hamilton theorem for higher rank matrices are obtained there from

Covariant gauge-natural conservation laws

When a gauge-natural invariant variational principle is assigned, to determine {\em canonical} covariant conservation laws, the vertical part of gauge-natural lifts of infinitesimal principal automorphisms -- defining infinitesimal variations of sections of gauge-natural bundles -- must satisfy generalized Jacobi equations for the gauge-natural invariant Lagrangian. {\em Vice versa} all vertical parts of gauge-natural lifts of infinitesimal principal automorphisms which are in the kernel of generalized Jacobi morphisms are generators of canonical covariant currents and superpotentials. In particular, only a few gauge-natural lifts can be considered as {\em canonical} generators of covariant gauge-natural physical charges.Comment: 16 pages; presented at XXXVI Symposium on Math. Phys., Torun 09/06-12/06/04; the last paragraph of Section 3 has been reformulated, in particular a mistake in the equation governing the vertical part of gauge-natural lifts with respect to prolongations of principal connections (appearing e.g. in the vertical superpotential) has been correcte

Host circadian rhythms are disrupted during malaria infection in parasite genotype-specific manners

Infection can dramatically alter behavioural and physiological traits as hosts become sick and subsequently return to health. Such “sickness behaviours” include disrupted circadian rhythms in both locomotor activity and body temperature. Host sickness behaviours vary in pathogen species-specific manners but the influence of pathogen intraspecific variation is rarely studied. We examine how infection with the murine malaria parasite, Plasmodium chabaudi, shapes sickness in terms of parasite genotype-specific effects on host circadian rhythms. We reveal that circadian rhythms in host locomotor activity patterns and body temperature become differentially disrupted and in parasite genotype-specific manners. Locomotor activity and body temperature in combination provide more sensitive measures of health than commonly used virulence metrics for malaria (e.g. anaemia). Moreover, patterns of host disruption cannot be explained simply by variation in replication rate across parasite genotypes or the severity of anaemia each parasite genotype causes. It is well known that disruption to circadian rhythms is associated with non-infectious diseases, including cancer, type 2 diabetes, and obesity. Our results reveal that disruption of host circadian rhythms is a genetically variable virulence trait of pathogens with implications for host health and disease tolerance

Adaptive periodicity in the infectivity of malaria gametocytes to mosquitoes

Daily rhythms in behaviour, physiology, and molecular processes are expected to enable organisms to appropriately schedule activities according to consequences of the daily rotation of the Earth. For parasites, this includes capitalizing on periodicity in transmission opportunities and for hosts/vectors, this may select for rhythms in immune defence. We examine rhythms in the density and infectivity of transmission forms (gametocytes) of rodent malaria parasites in the host’s blood, parasite development inside mosquito vectors, and potential for onwards transmission. Furthermore, we simultaneously test whether mosquitoes exhibit rhythms in susceptibility. We reveal that at night, gametocytes are twice as infective, despite being less numerous in the blood. Enhanced infectiousness at night interacts with mosquito rhythms to increase sporozoite burdens four-fold when mosquitoes feed during their rest phase. Thus, changes in mosquito biting time (due to bed nets) may render gametocytes less infective, but this is compensated for by the greater mosquito susceptibility

A Characterisation of the Weylian Structure of Space-Time by Means of Low Velocity Tests

The compatibility axiom in Ehlers, Pirani and Schild's (EPS) constructive axiomatics of the space-time geometry that uses light rays and freely falling particles with high velocity, is replaced by several constructions with low velocity particles only. For that purpose we describe in a space-time with a conformal structure and an arbitrary path structure the radial acceleration, a Coriolis acceleration and the zig-zag construction. Each of these quantities give effects whose requirement to vanish can be taken as alternative version of the compatibility axiom of EPS. The procedural advantage lies in the fact, that one can make null-experiments and that one only needs low velocity particles to test the compatibility axiom. We show in addition that Perlick's standard clock can exist in a Weyl space only.Comment: to appear in Gen.Rel.Gra

Multi-transmission-line-beam interactive system

We construct here a Lagrangian field formulation for a system consisting of an electron beam interacting with a slow-wave structure modeled by a possibly non-uniform multiple transmission line (MTL). In the case of a single line we recover the linear model of a traveling wave tube (TWT) due to J.R. Pierce. Since a properly chosen MTL can approximate a real waveguide structure with any desired accuracy, the proposed model can be used in particular for design optimization. Furthermore, the Lagrangian formulation provides for: (i) a clear identification of the mathematical source of amplification, (ii) exact expressions for the conserved energy and its flux distributions obtained from the Noether theorem. In the case of uniform MTLs we carry out an exhaustive analysis of eigenmodes and find sharp conditions on the parameters of the system to provide for amplifying regimes