Effect of a preoperative intervention on preoperative and postoperative outcomes in low-risk patients awaiting elective coronary artery bypass graft surgery. A randomized, controlled trial

BACKGROUND

In publicly funded health care systems, a waiting period for such services as coronary artery bypass graft surgery (CABG) is common. The possibility of using the waiting period to improve patient outcomes should be investigated.

OBJECTIVE

To examine the effect of a multidimensional preoperative intervention on presurgery and postsurgery outcomes in low-risk patients awaiting elective CABG.

DESIGN

Randomized, controlled trial.

SETTING

A regional cardiovascular surgery center in a tertiary care hospital, southwestern Ontario, Canada.

PATIENTS

249 patients on a waiting list for elective CABG whose surgeries were scheduled for a minimum of 10 weeks from the time of study recruitment.

INTERVENTION

During the waiting period, the treatment group received exercise training twice per week, education and reinforcement, and monthly nurse-initiated telephone calls. After surgery, participation in a cardiac rehabilitation program was offered to all patients.

MEASUREMENTS

Postoperative length of stay was the primary outcome. Secondary outcomes were exercise performance, general health-related quality of life, social support, anxiety, and utilization of health care services.

RESULTS

Length of stay differed significantly between groups. Patients who received the preoperative intervention spent 1 less day [95% CI, 0.0 to 1.0 day] in the hospital overall (P = 0.002) and less time in the intensive care unit (median, 2.1 hours [CI, -1.2 to 16 hours]; P = 0.001). During the waiting period, patients in the intervention group had a better quality of life than controls. Improved quality of life continued up to 6 months after surgery. Mortality rates did not differ.

CONCLUSION

The waiting period for elective procedures, such as CABG, may be used to enhance in-hospital and early-phase recovery, improving patients' functional abilities and quality of life while reducing their hospital stay.

The development of the index of complexity, outcome and need (ICON)

This paper is based on the winning submission for the 1998 Chapman prize awarded by the British Orthodontic Society for an essay on a subject promoting the interests of orthodontics. The aim of the investigation is to develop a single index for assessing treatment inputs and outcomes. An international panel of 97 orthodontists gave subjective judgements on the need for treatment, treatment complexity, treatment improvement, and acceptability on a diverse sample of 240 initial and 98 treated study models. The occlusal traits in the study models were scored according to a defined numerical protocol. Five highly predictive occlusal traits were identified (IOTN Aesthetic Component, crossbite, upper arch crowding/ spacing, buccal segment antero-posterior relationships, and anterior vertical relationship) and then used to 'predict' the panelist's decisions using regression analysis. Cut-off values were determined for the dichotomous judgements by plotting specificity sensitivity and overall accuracy. Twenty percentile ranges were used to determine 5 grades of complexity and improvement. The index prediction of decisions for treatment need, had specificity 84.4 per cent, sensitivity 85.2 per cent, and overall accuracy 85 per cent. When used to predict treatment outcomes, the new index had specificity 64.8 per cent, sensitivity 70.1 per cent, and overall accuracy 68.1 per cent. The index could explain 75.6 per cent of the variance in the mean casewise complexity score and 63.5 per cent of the mean casewise improvement score. A new orthodontic index is proposed to assess treatment need, complexity, and outcome. It is based on international orthodontic opinion.

Overexpression and topology of the Shigella flexneri O-antigen polymerase (Rfc/Wzy)

Lipopolysaccharides (LPS), particularly the O-antigen component, are one of many virulence determinants necessary for Shigella flexneri pathogenesis. O-antigen biosynthesis is determined mostly by genes located in the rfb region of the chromosome. The rfc/wzy gene encodes the O-antigen polymerase, an integral membrane protein, which polymerizes the O-antigen repeat units of the LPS. The wild-type rfc/wzy gene has no detectable ribosome-binding site (RBS) and four rare codons in the translation initiation region (TIR). Site-directed mutagenesis of the rare codons at positions 4, 9 and 23 to those corresponding to more abundant tRNAs and introduction of a RBS allowed detection of the rfc/wzy gene product via a T7 promoter/polymerase expression assay. Complementation studies using the rfc/wzy constructs allowed visualization of a novel LPS with unregulated O-antigen chain length distribution, and a modal chain length could be restored by supplying the gene for the O-antigen chain length regulator (Rol/Wzz) on a low-copy-number plasmid. This suggests that the O-antigen chain length distribution is determined by both Rfc/Wzy and Rol/Wzz proteins. The effect on translation of mutating the rare codons was determined using an Rfc::PhoA fusion protein as a reporter. Alkaline phosphatase enzyme assays showed an approximately twofold increase in expression when three of the rare codons were mutated. Analysis of the Rfc/Wzy amino acid sequence using TM-PREDICT indicated that Rfc/Wzy had 10-13 transmembrane segments. The computer prediction models were tested by genetically fusing C-terminal deletions of Rfc/Wzy to alkaline phosphatase and beta-galactosidase. Rfc::PhoA fusion proteins near the amino-terminal end were detected by Coomassie blue staining and Western blotting using anti-PhoA serum. The enzyme activities of cells with the rfc/wzy fusions and the location of the fusions in rfc/wzy indicated that Rfc/Wzy has 12 transmembrane segments with two large periplasmic domains, and that the amino- and carboxy-termini are located on the cytoplasmic face of the membrane.

Voxel-based morphometry shows no decreases in cerebellar gray matter volume in essential tremor

OBJECTIVE

To investigate cerebellar gray matter volume in patients with essential tremor (ET).

METHODS

We used voxel-based morphometry (VBM) based on high-resolution T1-weighted MRI to compare gray and white matter density between 27 patients with ET and 27 age- and sex-matched healthy control subjects. Fourteen patients had only postural tremor, whereas 13 patients showed additional intention tremor.

RESULTS

VBM failed to demonstrate regional decreases in gray and white matter volume in patients with ET. There was, however, an expansion in gray matter depending on the type of tremor. Compared with age-matched control groups, patients with intention tremor showed a relative expansion of gray matter bilaterally in the region of the temporoparietal junction and the right middle occipital cortex.

CONCLUSIONS

The lack of a consistent decrease in gray and white matter density argues against a progressive neurodegenerative process in essential tremor that leads to a substantial decrease in cerebellar gray matter volume. Patients with predominant intention tremor show a relative expansion of gray matter areas involved in higher order visuospatial processing, which might represent a long-term result of adaptive reorganization compensating the higher demands on the visuospatial control of skilled movements in case of trembling.

High-dose rituximab and anti-MAG-associated polyneuropathy

Rituximab has been administered successfully in patients with polyneuropathy associated with antibodies to myelin-associated glycoprotein (anti-MAG). The authors present a follow-up study with high-dose rituximab. Increase of rituximab from 375 mg/m2 to a dose of 750 mg/m2 was well tolerated and led to clinical improvement in four of eight patients, along with improvement of nerve conduction velocities and a reduction of anti-MAG antibody titers.

Rates of hydration of fatty acids bound to unilamellar vesicles of phosphatidylcholine or to albumin

The rates of hydration of naturally occurring fatty acids bound to unilamellar vesicles of dimyristoylphosphatidylcholine were measured by following the rate of quenching of the inherent fluorescence of albumin. Rates of hydration of fatty acids bound to albumin could be estimated from the same data. The data show that these rates depend on the chain length and unsaturation of the fatty acid. Increasing chain length diminishes the rate of hydration whereas increasing unsaturation increases this rate. Rates of hydration of fatty acids bound to lipid vesicles appear to be rapid enough to account for intracellular movement between compartments in the absence of carrier proteins. It is uncertain whether this is true for hydration of fatty acids bound to albumin. Rates for this process are about 100-300 times slower vs. rates of hydration of fatty acids bound to lipid vesicles.

Analysis of Shigella flexneri wzz (Rol) function by mutagenesis and cross-linking: wzz is able to oligomerize

The modal length or degree of polymerization (dp) of the Shigella flexneri O-antigen is determined in an unknown manner by the Wzz/Rol protein. The Wzz protein is anchored into the cytoplasmic membrane by two transmembrane domains (TM1 amino acids 32-52; TM2 amino acids 295-315) with the central loop of the protein located in the periplasm. Plasmids were constructed encoding hybrid Wzz proteins consisting of regions of S. flexneri Wzz (WzzSF) and Salmonella typhimurium Wzz (WzzST). These imparted O-antigen modal chain lengths that implied that the carboxy-terminal region of Wzz was involved in chain length determination. Site-directed mutagenesis was undertaken to investigate the functional significance of highly conserved residues in amino-/carboxy-terminal domains of WzzSF. Some of the WzzSF variants resulted in O-antigen modal chain lengths much shorter than those of wild-type WzzSF, whereas other mutants inactivated WzzSF function entirely and a third class had a longer O-antigen chain length distribution. The data indicate that amino acids throughout the length of the WzzSF protein are important in determination of O-antigen modal chain length. In vivo cross-linking experiments were performed to investigate the interactions between Wzz proteins. The experiments indicated that the WzzSF protein is able to form dimers and oligomers of at least six WzzSF proteins. A carboxy-terminal-truncated WzzSF protein having the amino terminal 194 amino acids was able to oligomerize, indicating that the amino-terminal region is sufficient for the Wzz-Wzz interaction observed. Shortened WzzSF proteins having internal deletions in the amino-terminal region were also able to oligomerize, suggesting that residues 59-194 are not essential for oligomerization. Cross-linking of WzzSF proteins with mutationally altered residues showed that loss of WzzSF function may be correlated to a reduced/altered ability to form oligomers, and that mutational alteration of glycine residues in the TM2 segment affects WzzSF-WzzSF dimer mobility in SDS polyacrylamide gels. These results provide the first evidence of protein-protein interactions for proteins involved in O-antigen polysaccharide biosynthesis.

Three-component-mediated serotype conversion in Pseudomonas aeruginosa by bacteriophage D3

Bacteriophage D3 is capable of lysogenizing Pseudomonas aeruginosa PAO1 (serotype O5), converting the O-antigen from O5 to O16 and O-acetylating the N-acetylfucosamine moiety. To investigate the mechanism of lysogenic conversion, a 3.6 kb fragment from the D3 genome was isolated capable of mediating serotypic conversion identical to the D3 lysogen strain (AK1380). The PAO1 transformants containing this 3.6 kb of D3 DNA exhibited identical lipopolysaccharide (LPS) banding patterns to serotype O16 in silver-stained SDS-PAGE gels and displayed reactivity to an antibody specific for O-acetyl groups. Further analysis led to the identification of three open reading frames (ORFs) required for serotype conversion: an alpha-polymerase inhibitor (iap); an O-acetylase (oac); and a beta-polymerase (wzybeta). The alpha-polymerase inhibitor (Iap) is capable of inhibiting the assembly of the serotype-specific O5 B-band LPS and allows the phage-encoded beta-polymerase (Wzybeta) to form new beta-linked B-band LPS. The D3 phage also alters the LPS by the addition of O-acetyl groups to the FucNAc residue in the O-antigen repeat unit by the action of the D3 O-acetylase (Oac). These three components form a simple yet elegant system by which bacteriophage D3 is capable of altering the surface of P. aeruginosa PAO1.

Sweet taste transduction in hamster: sweeteners and cyclic nucleotides depolarize taste cells by reducing a K+ current

1. The gigaseal voltage-clamp technique was used to record responses of hamster taste receptor cells to synthetic sweeteners and cyclic nucleotides. Voltage-dependent currents and steady-state currents were monitored during bath exchanges of saccharin, two high-potency sweeteners, 8-chlorophenylthio-adenosine 3',5'-cyclic monophosphate (8cpt-cAMP), and dibutyryl-guanosine 3',5'-cyclic monophosphate (db-cGMP). 2. Of the 237 fungiform taste cells studied, only one in eight was sweet responsive. Outward currents, both voltage-dependent and resting, were reduced by all of the sweeteners tested in sweet-responsive taste cells, whereas these currents were unaffected by sweeteners in sweet-unresponsive taste cells. 3. In every sweet-responsive cell tested, 8cpt-cAMP and db-cGMP mimicked the response to the sweeteners, but neither nucleotide elicited responses in sweet-unresponsive cells. Thus there was a one-to-one correlation between sweet responsivity and cyclic nucleotide responsivity. 4. Sweet responses showed cross adaptation with cyclic nucleotide responses. This indicates that the same ion channel is modulated by sweeteners and cyclic nucleotides. 5. The sweetener- and cyclic nucleotide-blocked current had an apparent reversal potential of -50 mV, which was close to the potassium reversal potential in these experiments. In addition, there was no effect of sweeteners and cyclic nucleotides in the presence of the K+ channel blocker tetraethylammonium bromide (TEA). These data suggest that block of a resting, TEA-sensitive K+ current is the final common step leading to taste cell depolarization during sweet transduction. 6. These data, together with data from a previous study (Cummings et al. 1993), suggest that both synthetic sweeteners and sucrose utilize second-messenger pathways that block a resting K+ conductance to depolarize the taste cell membrane.

A comparison of artificial saliva and pilocarpine in the management of xerostomia in patients with advanced cancer

This was a crossover study comparing a mucin-based artificial saliva (Saliva Orthana) and pilocarpine hydrochloride (Salagen) in the management of xerostomia in patients with advanced cancer. The pilocarpine was found to be more effective than the artificial saliva in terms of mean change in visual analogue scale scores for xerostomia (P = 0.003). Furthermore, more patients reported that it had helped their xerostomia, and more patients wanted to continue with it after the study. However, the pilocarpine was found to be associated with more side-effects than the artificial saliva (P < 0.001). These side-effects were usually reported as being mild. Of the patients who used both treatments, 50% preferred the artificial saliva, and 50% preferred the pilocarpine. The commonest reason for preferring the artificial saliva was the fact that it was a spray, rather than a tablet.

The European Multiple System Atrophy-Study Group (EMSA-SG)

Introduction. The European Multiple System Atrophy-Study Group (EMSA-SG) is an academic network comprising 23 centers across Europe and Israel that has constituted itself already in January 1999. This international forum of established experts under the guidance of the University Hospital of Innsbruck as coordinating center is supported by the 5th framework program of the European Union since March 2001 (QLK6-CT-2000-00661). Objectives. Primary goals of the network include (1) a central Registry for European multiple system atrophy (MSA) patients, (2) a decentralized DNA Bank, (3) the development and validation of the novel Unified MSA Rating Scale (UMSARS), (4) the conduction of a Natural History Study (NHS), and (5) the planning or implementation of interventional therapeutic trials. Methods. The EMSA-SG Registry is a computerized data bank localized at the coordinating centre in Innsbruck collecting diagnostic and therapeutic data of MSA patients. Blood samples of patients and controls are recruited into the DNA Bank. The UMSARS is a novel specific rating instrument that has been developed and validated by the EMSA-SG. The NHS comprises assessments of basic anthropometric data as well as a range of scales including the UMSARS, Unified Parkinson's Disease Rating Scale (UPDRS), measures of global disability, Red Flag list, MMSE (Mini Mental State Examination), quality of live measures, i.e. EuroQoL 5D (EQ-5D) and Medical Outcome Study Short Form (SF-36) as well as the Beck Depression Inventory (BDI). In a subgroup of patients dysautonomic features are recorded in detail using the Queen Square Cardiovascular Autonomic Function Test Battery, the Composite Autonomic Symptom Scale (COMPASS) and measurements of residual urinary volume. Most of these measures are repeated at 6-monthly follow up visits for a total study period of 24 months. Surrogate markers of the disease progression are identified by the EMSA-SG using magnetic resonance and diffusion weighted imaging (MRI and DWI, respectively). Results. 412 patients have been recruited into the Registry so far. Probable MSA-P was the most common diagnosis (49% of cases). 507 patients donated DNA for research. 131 patients have been recruited into the NHS. There was a rapid deterioration of the motor disorder (in particular akinesia) by 26.1% of the UMSARS II, and - to a lesser degree - of activities of daily living by 16.8% of the UMSARS I in relation to the respective baseline scores. Motor progression was associated with low motor or global disability as well as low akinesia or cerebellar subscores at baseline. Mental function did not deteriorate during this short follow up period. Conclusion. For the first time, prospective data concerning disease progression are available. Such data about the natural history and prognosis of MSA as well as surrogate markers of disease process allow planning and implementation of multi-centre phase II/III neuroprotective intervention trials within the next years more effectively. Indeed, a trial on growth hormone in MSA has just been completed, and another on minocycline will be completed by the end of this year.

A microsatellite genetic linkage map for Xiphophorus

Interspecies hybrids between distinct species of the genus Xiphophorus are often used in varied research investigations to identify genomic regions associated with the inheritance of complex traits. There are 24 described Xiphophorus species and a greater number of pedigreed strains; thus, the number of potential interspecies hybrid cross combinations is quite large. Previously, select Xiphophorus experimental crosses have been shown to exhibit differing characteristics between parental species and among the hybrid fishes derived from crossing them, such as widely differing susceptibilities to chemical or physical agents. For instance, genomic regions harboring tumor suppressor and oncogenes have been identified via linkage association of these loci with a small set of established genetic markers. The power of this experimental strategy is related to the number of genetic markers available in the Xiphophorus interspecies cross of interest. Thus, we have undertaken the task of expanding the suite of easily scored markers by characterization of Xiphophorus microsatellite sequences. Using a cross between Xiphophorus maculatus and X. andersi, we report a linkage map predominantly composed of microsatellite markers. All 24 acrocentric chromosome sets of Xiphophorus are represented in the assembled linkage map with an average intergenomic distance of 7.5 cM. Since both male and female F1 hybrids were used to produce backcross progeny, these recombination rates were compared between "male" and "female" maps. Although several genomic regions exhibit differences in map length, male- and female-derived maps are similar. Thus Xiphophorus, in contrast to zebrafish, Danio rerio, and several other vertebrate species, does not show sex-specific differences in recombination. The microsatellite markers we report can be easily adapted to any Xiphophorus interspecies and some intraspecies crosses, and thus provide a means to directly compare results derived from independent experiments.

Expression and rescuing of a cloned human tumour necrosis factor gene using an EBV-based shuttle cosmid vector

A cosmid vector carrying the Epstein-Barr virus origin of replication, the EBNA-1 gene, the hygromycin phosphotransferase (hph) gene and pBR322 sequences has been constructed. This cosmid can replicate autonomously in the nucleus of human tissue culture cells, even when it carries a 35-kb long insert. The cosmid can be rescued from the transfected cells by cloning it directly into ampicillin-sensitive Escherichia coli. A gene for human tumour necrosis factor (TNF) cloned into this cosmid vector was introduced in tissue culture cells, where it was transcribed into mature mRNA.

Rate dependency of the human cortical network subserving executive functions during generation of random number series--a functional magnetic resonance imaging study

In a random number generation (RNG) task subjects are instructed to generate the numbers 1-10 in a random fashion. RNG performance is assumed to involve executive functions, as it requires controlled response generation and suppression of habitual responses. To investigate cerebral structures involved in RNG associated executive functions we investigated functional magnetic resonance imaging in eight healthy subjects while performing an RNG task at two different response rates (1 and 2 Hz). During the 1 Hz condition an activation was detected bilaterally in the dorsolateral prefrontal cortex (BA 9/46), the lateral premotor cortex (BA 6), the anterior cingulate (BA 32), the inferior and superior parietal cortex (BA 7/40) and the cerebellar hemispheres. In the 2 Hz condition behavioural data showed higher counting tendencies reflecting poorer executive control. In parallel, a homogenous diminution of the activity in the involved cortical areas was obtained. This finding would support the theory of a cortical network involved in executive functions consisting of distinct brain regions working together rather than a distinct fronto-cortical functional localisation.

A comparison of the index of complexity outcome and need (ICON) with the peer assessment rating (PAR) and the index of orthodontic treatment need (IOTN)

AIM

To evaluate any relationship between ICON, IOTN and PAR. To establish whether or not ICON could replace these indices as a measure of orthodontic treatment complexity, outcome and need.

METHOD

The study models of 55 consecutively treated cases were examined and PAR, IOTN and ICON recorded.

RESULTS

The study showed significant correlations between IOTN and ICON with respect to need and PAR and ICON with respect to outcome.

CONCLUSION

It appears that ICON does reflect UK opinion and the current study provides some evidence that ICON may effectively replace PAR and IOTN as a means of determining need and outcome.

Changes in exercise capacity and lipids after clinic versus home-based aerobic training in coronary artery bypass graft surgery patients

PURPOSE

Despite the documented benefits of participating in rehabilitation programs, access to cardiac rehabilitation is limited for a large number of people with coronary artery disease (CAD). There is potential to increase participation in exercise training if home-based exercise were a viable option.

METHODS

We conducted a retrospective database review of 1,042 patients who took part in exercise rehabilitation following coronary artery bypass graft surgery (CABGS) between 1992 and 1998. Of these, 713 patients took part in supervised exercise, and 329 were in an unsupervised, home-based group. All exercise protocols were based upon American College of Sports Medicine guidelines, and patients in both groups received exercise prescriptions that were similar in intensity, frequency, and duration.

RESULTS

There were no differences between groups at baseline. Following 6 months of exercise training, there were substantial improvements in peak VO2, peak workload, and peak MET levels in both the supervised and unsupervised groups (P < 0.0001). Patients in the supervised group had significant improvements in both LDL and HDL-cholesterol, whereas the home-based group showed improvement in HDL-cholesterol only. When analyzed by sex, men performed better than women for all measures of exercise capacity; however, women in both groups showed approximate 20% improvements (P < 0.05) in exercise capacity as well as improvements in HDL-cholesterol.

CONCLUSION

Stable post CABGS patients who receive a detailed exercise prescription to follow at home do as well as those in supervised rehabilitation.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

PhoP/Q regulated genes in Salmonella typhi identification of melittin sensitive mutants

Many of the genes (pags (phoP activated genes) and prgs (phoP repressed genes)) regulated by the PhoP and PhoQ proteins (PhoP/Q) are necessary for survival of Salmonella typhimurium in murine macrophages and pathogenesis in mice. Although a great deal is known about the S. typhimurium phoP/Q regulon, little has been done with the human specific pathogen S. typhi, prompting us to investigate S. typhi phoP/Q regulated genes. Isogenic phoP12 (null) and phoP24 (constitutive) strains were constructed in S. typhi Ty2 and S. typhimurium C5 strains. Comparison of whole cell proteins from these strains by SDS-PAGE showed differences in both the number and molecular mass of PhoP/Q regulated proteins. This suggested that S. typhi and S. typhimurium may have different PhoP/Q regulated proteins and/or that their regulation may be different. A genetic procedure was developed to isolate mutations in PhoP/Q regulated genes. This involved random MudJ transposon mutagenesis of a phoP12 mutant, creating lacZ-gene fusions, and screening for Lac+ or Lac- colonies. A mobilizable plasmid carrying the phoP24 mutant gene was conjugated into these insertion mutants. Those that changed from Lac- to Lac+ were inferred to be pag::MudJ insertions and those that changed from Lac+ to Lac- were inferred to be prg::MudJ insertions. Five mutants with PhoP/Q regulated MudJ fusions were found by this scheme. The mutations were termed pqa (PhoPQ activated) and pqr (PhoPQ repressed) to distinguish them from other PhoP/Q regulated genes. The pqa/pqr::MudJ mutations were transduced into S. typhi phoP+ and phoP24 strains by Vi-l phage transduction. Characterization of the mutants (Southern blot analysis, beta-galactosidase activity on indicator plates and in liquid cultures) strongly suggested that their MudJ insertion mutations were in five different genes. Further characterization involved determining cationic peptide sensitivity and mouse virulence. Two mutants were found to be sensitive to the antimicrobial peptide melittin.

Olfactory event-related potentials in patients with brain tumors

OBJECTIVE

The aim of the study was to determine how odor processing is altered in patients with unilateral supratentorial brain tumors.

METHODS

Olfactory event-related potentials (OERPs) were evaluated in 10 patients with unilateral brain tumors of the frontal or temporal lobe in response to linalool and allylcaproate. Both odors were presented monorhinally by a constant-flow olfactometer. In addition, 20 healthy subjects were examined. While sniffing, the subjects were asked to discriminate the two odors. EEG was recorded from 7 electrode positions (Fz, Cz, Pz, F3/4, P3/4). Amplitudes and latencies of 3 peaks (N1, P2, P3) were measured. To control for effects of modality-non-specific alterations on the olfactory components acoustic event-related potentials (AERPs) were registered by use of an oddball paradigm.

RESULTS

Patients with right-sided lesions showed distinct deficits in the discrimination task after stimulation of the right and left nostril. In contrast, patients with left-sided lesions only had an attenuation of correct reactions after left-sided stimulation. In the OERPs, patients with right-sided lesions showed P2- and P3-components with decreased amplitudes at parietal electrode positions. These alterations appeared after ipsi- and contralateral stimulation. Patients with left-sided lesions showed a significant effect of the side of stimulation. Their OERP-amplitudes were decreased after left-sided stimulation but not after right-sided stimulation. After right-sided olfactory stimulation a correlation between the olfactory and the acoustic ERP was seen in patients with right-sided lesions.

CONCLUSIONS

Olfactory performance of the participating patients was markedly reduced. Patients with right-sided lesions showed bilateral impairment, which would support the importance of the right hemisphere in olfaction. The alteration of the topographic distribution of P2- and P3-amplitudes in patients with right-sided lesions might reflect an impairment of early and late olfactory processing steps.

The eastern extent of seasonal iron limitation in the high latitude North Atlantic Ocean

The availability of iron (Fe) can seasonally limit phytoplankton growth in the High Latitude North Atlantic (HLNA), greatly reducing the efficiency of the biological carbon pump. However, the spatial extent of seasonal iron limitation is not yet known. We present autumn nutrient and dissolved Fe measurements, combined with microphytoplankton distribution, of waters overlying the Hebridean (Scottish) shelf break. A distinct biogeochemical divide was observed, with Fe deficient surface waters present beyond the shelf break, much further eastwards than previously recognised. Due to along and on-shelf circulation, the Hebridean shelf represents a much-localised source of Fe, which does not fertilise the wider HLNA. Shelf sediments are generally thought to supply large quantities of Fe to overlying waters. However, for this Fe to influence upper-ocean biogeochemical cycling, efficient off-shelf transport mechanisms are required. This work challenges the view that the oceanic surface waters in close proximity to continental margins are iron replete with respect to marine primary production demands.