Methylprednisolone favourably alters plasma and urinary cytokine homeostasis and subclinical renal injury at cardiac surgery

Whilst elevated urinary transforming growth factor beta-1 (TGFbeta) is associated with chronic renal dysfunction its role in acute peri-operative renal dysfunction is unknown. In contrast, peri-operative increases in urinary IL-1 receptor antagonist (IL-1ra) and TNF soluble receptor-2 (TNFsr-2) mirror pro-inflammatory activity in the nephron and correlate with renal complications. Steroids modulate some plasma cytokines (decreasing TNFalpha, IL-8, IL-6 and increasing IL-10), whereas ability to reduce plasma and urinary TNFsr-2 and IL-1ra and peri-operative renal injury is unknown. Patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CPB) were randomised to receive methylprednisolone (n = 18) or placebo (n = 17) before induction of anaesthesia. Plasma and urinary pro- and anti-inflammatory cytokine balance was determined along with subclinical proximal tubular injury and dysfunction, measured by urinary N-acetyl-beta-d-glucosaminidase (NAG)/creatinine and alpha-1-microglobulin/creatinine ratios, respectively. In the control group compared with baseline, plasma IL-8, TNFalpha, IL-10, IL-1ra and TNFsr-2 were significantly elevated along with urinary IL-1ra, TNFsr-2 and TGFbeta1. Urinary NAG/creatinine and alpha-1-microglobulin/creatinine ratios rose from completion of revascularisation until 6 h with recovery at 24 h with a further rise in NAG/creatinine ratio at 48 h. Compared to placebo, the methylprednisolone group showed significantly reduced plasma IL-8, TNFalpha, IL-1ra and TNFsr-2 whereas plasma IL-10 increased. Compared to placebo, the methylprednisolone group demonstrated significantly reduced urinary NAG/creatinine ratio, TNFsr-2 and TGFbeta1 at 24 h whereas urinary alpha-1-microglobulin/creatinine ratios increased.

CONCLUSIONS

Methylprednisolone administration during cardiac surgery significantly reduces plasma and urinary TNFsr-2 and IL-1ra, urinary TGFbeta1 and subclinical renal injury but not dysfunction.

The relationship of falls to injury among hospital in-patients

The need to reduce falls is driven by the need to reduce injury. If patients at risk of injury can be distinguished from the patients at risk of falls, there is the potential for a more effective fall risk management policy by targeting injury prevention measures. We conducted a prospective observational study, with blinded endpoint evaluation of 825 consecutive patients admitted to geriatric rehabilitation wards. We identified 150 fallers (18.2%) contributing 243 falls. Fifty-six patients sustained an injury contributing 73 (30.0%) injurious falls. Only five (6.8%) falls resulted in injury of major severity. We identified no significant differences in demographics between injurious and non-injurious falls. A logistic regression analyses of the independent risk factors of suffering an injurious fall were a history of falls (p=0.036), confusion (p=0.001) and an unsafe gait (p=0.03). However, we identified no significant differences in clinical characteristics between patients suffering injurious and non-injurious falls. None of the characteristics studied can identify patients prone to injury after a fall. Injury is largely unpredictable, and more research is needed to determine how injury can be prevented in patients at risk of falls.

Enhanced removal of organic matter and ammoniacal-nitrogen in a column experiment of tidal flow constructed wetland system

A tidal flow constructed wetland system was investigated for the removal of organic matter and ammoniacal-nitrogen from diluted piggery wastewater. The results demonstrated that the operation of tidal flow enhanced the transfer of oxygen into wetland matrices. The supply of oxygen by the operation (473 gO2/m2d) matched the demand for wastewater treatment. The overall oxygen consumption rate in the system was considerably higher than the typical rate obtainable in conventional wetlands; most oxygen being used for the decomposition of organic matter. Compared with conventional systems, the tidal flow system demonstrated greater efficiency in the removal of organic matter. Significant nitrification did not take place, although 27-48% ammonia was removed from the wastewater. Immobilization by microbial cells and adsorption were the likely routes to remove ammonia under the specific experiment conditions. Percentage removals of BOD5, NH4-N and SS increased after effluent recirculation at a ratio of 1:1 was employed.

A comparative study of the sensitivity of the 3-induction and 9-induction Buehler test procedures for assessing skin sensitisation potential

Assessment of skin sensitization potential is a mandatory requirement for the registration or notification of most types of chemicals and products. Until recently, two methods using the guinea pig as test model were the most widely accepted; the guinea pig maximisation test and the Buehler test. In the case of agrochemical formulations, which constitute the final end use product in contact with operators, industry and also some regulatory authorities consider the Buehler method more appropriate as the methodology is more relevant to likely exposure in the field. However, certain European regulatory authorities have become concerned about the sensitivity of the Buehler test for this purpose and have requested that a modified method is used in which additional applications of test materials are used during the induction phase of the protocol (a total of 9 rather than the normal 3). This study was designed to assess whether this modification was justified. Six reference substances (formaldehyde, alpha-hexylcinnamaldehyde, fragrance mix, thimerosal, mercaptobenzothiazole and phthalic anhydride); all mild to moderate skin sensitizing chemicals, were assessed in a study, which compared the use of 3 and 9 induction applications. The results of this study demonstrated that, although most of these sensitisers were detected by both protocols, the modified method (9 induction applications) was no more sensitive than the standard method (3 induction applications). As the modified protocol is also potentially more stressful to the animals, it is concluded that the use of additional induction applications in the Buehler test cannot be justified from either a scientific or an animal welfare perspective.

Exploring the mechanisms regulating regeneration of deer antlers

Deer antlers are the only mammalian appendages capable of repeated rounds of regeneration; every year they are shed and regrow from a blastema into large branched structures of cartilage and bone that are used for fighting and display. Longitudinal growth is by a process of modified endochondral ossification and in some species this can exceed 2 cm per day, representing the fastest rate of organ growth in the animal kingdom. However, despite their value as a unique model of mammalian regeneration the underlying mechanisms remain poorly understood. We review what is currently known about the local and systemic regulation of antler regeneration and some of the many unsolved questions of antler physiology are discussed. Molecules that we have identified as having potentially important local roles in antlers include parathyroid hormone-related peptide and retinoic acid (RA). Both are present in the blastema and in the rapidly growing antler where they regulate the differentiation of chondrocytes, osteoblasts and osteoclasts in vitro. Recent studies have shown that blockade of RA signalling can alter cellular differentiation in the blastema in vivo. The trigger that regulates the expression of these local signals is likely to be changing levels of sex steroids because the process of antler regeneration is linked to the reproductive cycle. The natural assumption has been that the most important hormone is testosterone, however, at a cellular level oestrogen may be a more significant regulator. Our data suggest that exogenous oestrogen acts as a 'brake', inhibiting the proliferation of progenitor cells in the antler tip while stimulating their differentiation, thus inhibiting continued growth. Deciphering the mechanism(s) by which sex steroids regulate cell-cycle progression and cellular differentiation in antlers may help to address why regeneration is limited in other mammalian tissues.

Direct atomic force microscopy observations of monovalent ion induced binding of DNA to mica

Multivalent ions in solution are known to mediate attraction between two like-charged molecules. Such attraction has proved useful in atomic force microscopy (AFM) where DNA may be immobilized to a mica surface facilitating direct imaging in liquid. Theories of DNA immobilization suggest that either 'salt bridging' or fluctuation in the positions of counter ions about both the mica surface and DNA backbone secure DNA to the mica substrate. Whilst both theoretical and experimental evidence suggest that immobilization is possible in the presence of divalent ions, very few studies identify that such immobilization is possible with monovalent ions. Here we present direct AFM evidence of DNA immobilized to mica in the presence of only monovalent ions. Our data depict E. coli plasmid pBR322 adsorbed onto the negatively charged mica both after short (10 min) and long (24 h) incubation periods. These data suggest the need to re-explore current theories of like-charge attraction to include the possibility of monovalent interactions. We suggest that this DNA immobilization strategy may offer the potential to image natural processes with limited immobilization forces and hence enable maximum conformational freedom of the immobilized biomolecule.

Detection of severe protein-energy malnutrition by nurses in The Gambia

AIM

To test whether nurses can use the WHO integrated management of childhood illness (IMCI) nutrition algorithm to identify reliably severe protein-energy malnutrition in children.

METHODS

Nurses were trained to identify severe protein-energy malnutrition using IMCI training materials. They identified visible severe wasting and bipedal oedema, and categorised weight-for-age using a growth chart, in consecutive children attending outpatient clinics. Their findings were compared with weight for height Z (WHZ) score, bipedal oedema assessed by a trained observer, and weight-for-age Z score.

RESULTS

A total of 352 children were recruited, of whom 34 (9.7%) were severely wasted (WHZ score <-3) and 18 (5.1%) had bipedal oedema. In the detection of severe wasting, the nurses' assessments showed 56% sensitivity, 95% specificity, and 56% positive predictive value (PPV), and for bipedal oedema 22%, 99%, and 57% respectively. Overall, the nurses identified only half of 50 children with severe wasting and/or bipedal oedema and wrongly identified a further 13 children as severely malnourished. Plotting weight for age by the nurses showed 62% sensitivity, 99% specificity, and 89% PPV for the detection of children with very low weight.

CONCLUSIONS

Severe malnutrition was both under-diagnosed and wrongly diagnosed by nurses trained in the use of the IMCI nutrition algorithm in a clinic setting in The Gambia. These guidelines for health workers and the training materials, particularly with respect to calculation of age, need further development to improve the detection of malnourished children.

Recapitulation of the parathyroid hormone-related peptide-Indian hedgehog pathway in the regenerating deer antler

Parathyroid hormone (PTH)-related peptide (PTHrP) and the PTH/PTHrP receptor (PPR) play an essential role in controlling growth plate development. The aim of the present study was to use the deer antler as a model to determine whether PTHrP and PPR may also have a function in regulating cartilage and bone regeneration in an adult mammal. Antlers are the only mammalian appendages that are able to undergo repeated cycles of regeneration, and their growth from a blastema involves a modified endochondral process. Immunohistochemistry was used to establish sites of localization of PTHrP and PPR in antlers at different stages of development. The pattern of Indian Hedgehog (IHH) and transforming growth factor-beta1 (TGF beta1) distribution was also investigated, because PTHrP expression in the developing limb is regulated by IHH and during embryonic growth plate formation TGF beta1 acts upstream of PTHrP to regulate the rate of chondrocyte differentiation. In the antler blastema (<10 days of development), PTHrP, PPR, and TGF beta1 were localized in epidermis, dermis, regenerating epithelium, and in mesenchymal cells but IHH expression was not detected. In the rapidly growing antler (weeks 4-8 of development), PTHrP, PPR, and TGF beta1 were localized in skin, perichondrium, undifferentiated mesenchyme, recently differentiated chondrocytes, and in perivascular cells in cartilage but not in fully differentiated hyperytrophic chondrocytes. IHH was restricted to recently differentiated chondrocytes and to perivascular cells in cartilage. In mineralized cartilage and bone, PTHrP, PPR, IHH, and TGF beta1 were immunolocalized in perivascular cells and differentiated osteoblasts. PTHrP and PPR were also present in the periosteum. TGF beta1 in vitro stimulated PTHrP synthesis by cells from blastema, perichondrium, and cartilage. The findings of this study suggest that molecules which regulate embryonic skeletal development and postnatal epiphyseal growth may also control blastema formation, chondrogenesis, and bone formation in the regenerating deer antler. This finding is further evidence that developmental signaling pathways are recapitulated during adult mammalian bone regeneration.

Evaluation of body weight as a predictive factor for transvenous ventricular defibrillation characteristics

AIMS

To investigate the correlation between body weight and defibrillation threshold (DFT) for transvenous lead systems using a porcine model.

METHODS AND RESULTS

Twenty-eight pigs were anaesthetised and DFTs assessed in single and dual coil configurations using a four-reversal binary search method. DFT was correlated with body weight in the RV --> Can and RV --> SVC + Can configurations. A Pearson correlation coefficient and a two-sided p-value were calculated. A positive correlation exists between body weight and DFT in RV --> Can (r=0.66, p<0.000) and RV --> SVC + Can (r=0.44, p=0.018).

CONCLUSION

There is a significant correlation between body weight and DFT in swine. This tends to be greater in the two-electrode than in the three-electrode configuration. With these and previous human observations, one may predict a higher DFT in heavy individuals and make appropriate procedural adjustments.

Measuring and visualizing single molecular interactions in biology

In recent years, considerable attention has focused upon the biological applications of the atomic force microscope (AFM), and in particular in its ability to explore biomolecular interaction events at the single molecule level. Such measurements can provide considerable advantages, as they remove the data averaging inherent in other biophysical/biochemical approaches that record measurements over large ensembles of molecules. To this end AFM has been used for both the high-resolution imaging of a range of individual biological molecules and their complexes, and to record interaction forces between single interacting molecules. In a recently initiated project we have begun to utilize these approaches to explore the interactions of a range of biologically important peptides with model and cell membrane surfaces. In this review, the potential value of AFM for the investigation of a range of biomolecular interaction events will be discussed, but highlighting in particular its potential for the study of interactions of peptides/proteins with biological membranes.

Adult respiratory distress syndrome as a severe immune reconstitution disease following the commencement of highly active antiretroviral therapy

We report a patient who developed adult respiratory distress syndrome (ARDS) secondary to Mycobacterium tuberculosis as an immune reconstitution disease. This complication occurred 14 days after the commencement of highly active antiretroviral therapy (HAART) for advanced HIV infection. The case emphasises that immune reconstitution can be an extremely aggressive complication of HAART.

Electrostatic interactions observed when imaging proteins with the atomic force microscope

The atomic force microscope (AFM) is now an established and valuable tool for the study of biological macromolecules in aqueous environments. In this paper we form a patterned boundary via the microcontact printing of individually isolated proteins, covalently attached to a solid support. We use this boundary to investigate electrostatic interactions that can occur between an AFM tip and a protein surface during imaging in solution. The observed height variations of the protein film are found to be a combination of not only structural considerations and thickness of the protein film, but also the repulsive contribution from electrostatic interactions between the AFM tip and the sample. These variations in measured heights of the protein surface can be described by Derjaguin, Landau, Verway, Overbeek (DLVO) theory. Our experimental results show that height measurements can be manipulated either negatively or positively by adjusting the pH and concentration of the electrolyte buffer that is utilised.

A review of neurological disorders presenting at a paediatric neurology clinic and response to anticonvulsant therapy in Gambian children

A clinical review of 128 children presenting at the paediatric neurology clinic of the Royal Victoria Hospital, The Gambia was conducted between July 2001 and January 2002. The aim was to assess the spectrum and burden of neurological disease presenting at this tertiary-level clinic and to evaluate the effectiveness of anticonvulsant therapy. The principal clinical diagnoses most frequently made were seizures (57%), neuromotor problems (15%) and developmental delay (11%). Many children also had associated developmental delay or learning difficulties (55%), speech and language problems (42%) and physical disability (36%). Although 65% were considered to need assistance in the community, only 11% were receiving such help. There were 73 children with seizures, 80% of whom had a greater than 50% reduction in seizure frequency following the start of simple anticonvulsant medication. Of the children who had experienced more than 100 convulsions during the previous year, only 50% responded similarly to treatment. This review emphasises the need for improved community services and accessible medical care for children with neurological problems in West Africa.

Postnatal development of the hypothalamic neuropeptide Y system

In the adult rat, arcuate-neuropeptide Y/agouti-related protein neurons have efferent projections throughout the hypothalamus and provide a potent orexigenic stimulus. At birth neuropeptide Y fibers are also present throughout the hypothalamus; however, the source of these fibers has been unknown. The present studies determined the postnatal ontogeny of arcuate-neuropeptide Y fibers into the paraventricular nucleus and dorsomedial hypothalamic nucleus, as well as the ontogeny of neuropeptide Y1 receptor expression within these areas. Agouti-related protein messenger RNA and protein expression was present exclusively in cell bodies in the arcuate throughout postnatal development, starting at P2, and was colocalized in the vast majority of arcuate-neuropeptide Y neurons. This exclusive colocalization of agouti-related protein with arcuate-neuropeptide Y neurons makes it an excellent marker for these neurons and their projections. Even though single-label neuropeptide Y fibers were abundant in the dorsomedial hypothalamic nucleus and paraventricular nucleus as early as P2, arcuate-neuropeptide Y/agouti-related protein fibers did not significantly innervate these areas until P5-6 and P10-11, respectively. In contrast, a portion of the neuropeptide Y fibers within the paraventricular nucleus as early as P2 originated from the brainstem, as indicated by their colocalization with dopamine beta hydroxylase. It remains to be determined if local sources of neuropeptide Y-expressing cells within the dorsomedial hypothalamic nucleus and paraventricular nucleus also contribute to the neuropeptide Y-immunoreactive fibers within these regions prior to the development of arcuate-neuropeptide Y/agouti-related protein projections. In addition to the dramatic change in arcuate-neuropeptide Y/agouti-related protein projections, there is also a striking change in Y1 protein expression in the hypothalamus during the first two postnatal weeks. Taken together these data suggest that the early postnatal period, during which there is a dynamic change in the hypothalamic neuropeptide Y system, may constitute a critical period in the development of this important feeding circuit.

Comparison of coronary venous defibrillation with conventional transvenous internal defibrillation in man

OBJECTIVE

Animal studies have shown that defibrillation in coronary veins is more effective than in the right ventricle. We aimed to assess the feasibility of placing defibrillation electrodes in the middle cardiac vein (MCV) in man and its impact on defibrillation requirements.

METHODS

A prospective randomised study conducted in a tertiary referral centre. 10 patients (9 male) undergoing ICD implantation (65 (12) yrs) for NASPE/BPEG indications were studied. Defibrillation thresholds (DFT) were measured, using a binary search and an external defibrillator after 10 seconds of ventricular fibrillation, for the following configurations in each patient (order of testing randomised): RV + MCV --> Can and RV --> SVC + Can.

INTERVENTIONS

A dual coil defibrillation electrode was placed transvenously in the right ventricle (RV) in the conventional manner. Using a guiding catheter a 3.2 Fr (67.5 mm length) electrode was placed transvenously in MCV. A test-can was placed subcutaneously in the left pectoral region.

RESULTS

Lead placement was possible in 8/10 pts. Time to perform a middle cardiac venogram and place the electrode was 21 (23) mins. No adverse events were observed. Defibrillation current was less (6.7 (2.7) A) with RV + MCV --> Can compared to the conventional RV --> SVC + Can configuration (8.9 (3.4) A, p = 0.03). There was no significant difference in defibrillation voltage or energy. However, shock impedance was higher in the former configuration (57 (10) v. 43 (6) Omega, p = 0.001).

CONCLUSIONS

In the majority of cases placement of a defibrillation lead in MCV is feasible. Defibrillation current requirements are 25% less when the shock is delivered using a MCV electrode.

Fusarium wilt of cotton: a fatal fungal affliction?

Fusarium wilt is one of those uncommon phenomena where something so small does so much and motivates so many. It is a virulent, new fungal pathogen which is afflicting a vibrant modern industry in the Australian rural landscape. In this review, we examine the appearance of Fusarium wilt of cotton and the substantial response by the researchers and farming communities behind Australia?s third biggest rural export commodity.