The stoichiometry of the two photosystems in higher plants revisited

The stoichiometry of Photosystem II (PSII) to Photosystem I (PSI) reaction centres in spinach leaf segments was determined by two methods, each capable of being applied to monitor the presence of both photosystems in a given sample. One method was based on a fast electrochromic (EC) signal, which in the millisecond time scale represents a change in the delocalized electric potential difference across the thylakoid membrane resulting from charge separation in both photosystems. This method was applied to leaf segments, thus avoiding any potential artefacts associated with the isolation of thylakoid membranes. Two variations of this method, suppressing PSII activity by prior photoinactivation (in spinach and poplar leaf segments) or suppressing PSI by photo-oxidation of P700 (the chlorophyll dimer in PSI) with background far-red light (in spinach, poplar and cucumber leaf segments), each gave the separate contribution of each photosystem to the fast EC signal; the PSII/PSI stoichiometry obtained by this method was in the range 1.5-1.9 for the three plant species, and 1.5-1.8 for spinach in particular. A second method, based on electron paramagnetic resonance (EPR), gave values in a comparable range of 1.7-2.1 for spinach. A third method, which consisted of separately determining the content of functional PSII in leaf segments by the oxygen yield per single turnover-flash and that of PSI by photo-oxidation of P700 in thylakoids isolated from the corresponding leaves, gave a PSII/PSI stoichiometry (1.5-1.7) that was consistent with the above values. It is concluded that the ratio of PSII to PSI reaction centres is considerably higher than unity in typical higher plants, in contrast to a surprisingly low PSII/PSI ratio of 0.88, determined by EPR, that was reported for spinach grown in a cabinet under far-red-deficient light in Sweden [Danielsson et al. (2004) Biochim. Biophys. Acta 1608: 53-61]. We suggest that the low PSII/PSI ratio in the Swedish spinach, grown in far-red-deficient light with a lower PSII content, is not due to greater accuracy of the EPR method of measurement, as suggested by the authors, but is rather due to the growth conditions.

Early bactericidal activity of high-dose rifampin in patients with pulmonary tuberculosis evidenced by positive sputum smears

We studied the early bactericidal activity of twice the standard dose of rifampin in subjects with pulmonary tuberculosis evidenced by positive smears. The observed mean 2-day activity was almost double that reported at the standard dose. Further studies are warranted to establish whether higher rifampin doses might assist in shortening tuberculosis treatment.

ProgeniDB: a novel cell lineage database for generation associated phenotypic behavior in cell-based assays

ProgeniDB is a web-accessible cell lineage database, which comprises data derived from time-lapse microscopy image sequences, using our novel encoding software tool called ProgeniTRAK. This database provides information on qualitative and quantitative changes in cellular dynamics in response to anti-cancer drugs variation, which is critical for pharmacodynamic modeling and validation. The lineage data for each progenitor cell centers around the construction of a bifurcation map, locating in both space and time critical cellular events such as cell division and cell death. This database provides the opportunity to select a set of lineages based on different experimental constraints and observe the associated phenotypic behavior of progenitor cells. The output generated from this database depicts the cellular dynamic of selected population which can be downloaded to explore and exploit in relation to hypothesis-driven drug discovery. A case study is presented where we interrogate drug-induced perturbations on ensuing cell lineages. The database is available at http://biodiversity.cs.cf.ac.uk/cymart/progenidb.html.

Transcatheter embolisation of patent ductus arteriosus using an Amplatzer vascular plug in six dogs

OBJECTIVES

The objective of this study was to assess the feasibility of transcatheter embolisation of a patent ductus arteriosus using an Amplatzer vascular plug (Amplatzer Medical UK) in six dogs.

METHODS

The Amplatzer vascular plug is a self-expandable, cylindrical device attached to a delivery cable. In all the dogs, the device was delivered transvenously. Successful device implantation was defined as firm anchorage of the device squarely within the distal part of the ductus arteriosus with no intra- or postoperative dislodgement. Successful occlusion of the ductus arteriosus occurred if a disappearance of the continuous murmur was achieved 24 hours after placement of the Amplatzer vascular plug.

RESULTS

The age of the dogs ranged from 16 weeks to 7.5 years. Their weights ranged from 2.9 to 27.6 kg (median 6 kg). Two dogs had congestive heart failure before embolisation. Successful device implantation was achieved in all dogs. Successful occlusion of the ductus arteriosus was achieved in four of the six dogs. Complications included mild lameness, residual shunting, and bruising and pruritus around the surgical wound site. At follow-up, two dogs had a continuous murmur and one required treatment for congestive heart failure.

CLINICAL SIGNIFICANCE

This technique may represent a clinically effective and less expensive alternative to the use of an Amplatzer duct occluder (Amplatzer Medical UK) in dogs with medium-sized patent ductus arteriosus. Further investigations are required to fully evaluate its efficacy and safety in various sizes and types of patent ductus arteriosus, and to determine the optimal device size in relation to the size of the ductus.

Modification to improve efficiency of sampling schedules for BA/BE testing of FDC anti-tuberculosis drugs

SETTING

The assessment of rifampicin (RMP) containing fixed-dose combination (FDC) formulations using in vivo bioequivalence testing is widely accepted. It would be advantageous for both the drug regulatory authorities and drug manufacturers, for optimum minimum blood testing time intervals that encompass all anti-tuberculosis active constituents in the FDC to be established.

OBJECTIVE

To determine the optimum blood sampling schedule for testing novel FDC anti-tuberculosis drugs, isoniazid, RMP, pyrazinamide and ethambutol

DESIGN

The results of 12 different single-dose, two-way cross-over designs are presented. The studies determined the bioavailability and bioequivalence of RMP-containing FDCs, and conformed with the requirements of the South African national drug regulatory authority for each of the active constituents.

RESULTS

The pharmacokinetic parameters to determine bioavailability and the Hauschke method to determine bioequivalence revealed that a six-point time protocol, namely 0, 1, 2, 4, 6 and 8 h, provides a good approximation of the area under the curve, and that an 11-point time protocol of 0, 0.25, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6 and 8 h provided information comparable to the conventional 15 time-points for FDCs containing up to four drugs.

CONCLUSION

The findings provide concrete economic benefit and convenience for quality assurance testing of existing and novel FDCs.

Cytotoxic action of phorbol esters on human pancreatic cancer cells

We previously showed that phorbol esters are cytotoxic to human thyroid epithelial cells expressing a mutant RAS oncogene. Here we explore the generality of this finding using cells derived from pancreatic cancer, which, like thyroid, shows a high frequency of RAS mutation, but is a much greater cause of cancer mortality. The response to phorbol myristate acetate (PMA) and related agents was assessed on a panel of 9 pancreatic cancer cell lines, using a range of assays for cell growth and death in vitro and in vivo. In most lines, PMA induced non-apoptotic cell death which was, surprisingly, independent of its "classic" target, protein kinase C. With 24 hr exposure, the IC(50) in the most sensitive line (Aspc-1) was <1 ng/ml (1.6 nM), with survival undetectable at concentrations >/=>/=16 nM, and after only 1 hr exposure the IC(50) was still </=</=16 nM. Interestingly, the efficacy of a second phorbol ester, phorbol dibutyrate, was much lower, and the PMA analogue bryostatin-1, which is in clinical trials against other tumour types, was totally inactive. Pre-treatment of Aspc-1 cells with PMA before subcutaneous inoculation into nude mice prevented, or greatly retarded, subsequent xenograft tumour growth. Furthermore, treatment of established tumours with a single peri-tumoral injection of PMA induced extensive cell death and arrested tumour development. Taken together with recent Phase 1 clinical studies, these data suggest that activity against pancreatic cancer will be attainable by systemic administration of PMA, and point to potential novel therapeutic targets for this highly aggressive cancer.

Spectral analysis of the DNA targeting bisalkylaminoanthraquinone DRAQ5 in intact living cells

BACKGROUND

We report on the potential DNA binding modes and spectral characteristics of the cell-permeant far red fluorescent DNA dye, DRAQ5, in solution and bound within intact cells. Our aim was to determine the constraints for its use in flow cytometry and bioimaging.

METHODS

Solution characteristics and quantum yields were determined by spectroscopy. DRAQ5 binding to nuclear DNA was analyzed using fluorescence quenching of Hoechst 33342 dye, emission profiling by flow cytometry, and spectral confocal laser scanning microscopy of the complex DRAQ5 emission spectrum. Cell cycle profiling utilized an EGFP-cyclin B1 reporter as an independent marker of cell age. Molecular modeling was used to explore the modes of DNA binding.

RESULTS

DRAQ5 showed a low quantum yield in solution and a spectral shift upon DNA binding, but no significant fluorescence enhancement. DRAQ5 caused a reduction in the fluorescence intensity of Hoechst 33342 in live cells prelabeled with the UV excitable dye, consistent with molecular modeling that suggests AT preference and an engagement of the minor groove. In vivo spectral analysis of DRAQ5 demonstrated shifts to longer wavelengths upon binding with DNA. Analysis of spectral windows of the dual emission peaks at 681 and 707 nm in cells showed that cell cycle compartment recognition was independent of the far red-near IR emission wavelengths monitored.

CONCLUSIONS

The study provides new clues to modes of DNA binding of the modified anthraquinone molecule in vivo, and its AT base-pair selectivity. The combination of low quantum yield but high DNA affinity explains the favorable signal-to-noise profile of DRAQ5-nuclear fluorescence. The robust nature of cell cycle reporting using DRAQ5, even when restricted spectral windows are selected, facilitates the analysis of encroaching spectral emissions from other fluorescent reporters, including GFP-tagged proteins.

QSAR models based on quantum topological molecular similarity

A new method called quantum topological molecular similarity (QTMS) was fairly recently proposed [J. Chem. Inf. Comp. Sc., 41, 2001, 764] to construct a variety of medicinal, ecological and physical organic QSAR/QSPRs. QTMS method uses quantum chemical topology (QCT) to define electronic descriptors drawn from modern ab initio wave functions of geometry-optimised molecules. It was shown that the current abundance of computing power can be utilised to inject realistic descriptors into QSAR/QSPRs. In this article we study seven datasets of medicinal interest : the dissociation constants (pK(a)) for a set of substituted imidazolines , the pK(a) of imidazoles , the ability of a set of indole derivatives to displace [(3)H] flunitrazepam from binding to bovine cortical membranes , the influenza inhibition constants for a set of benzimidazoles , the interaction constants for a set of amides and the enzyme liver alcohol dehydrogenase , the natriuretic activity of sulphonamide carbonic anhydrase inhibitors and the toxicity of a series of benzyl alcohols. A partial least square analysis in conjunction with a genetic algorithm delivered excellent models. They are also able to highlight the active site, of the ligand or the molecule whose structure determines the activity. The advantages and limitations of QTMS are discussed.

Effect of spinal flexion on the conus medullaris: a case series using magnetic resonance imaging

Anatomy textbooks state that the conus medullaris moves cephalad when the vertebral column is flexed. This could confer protection against spinal cord damage during dural puncture, but has not been demonstrated in vivo. We therefore imaged the spine of 10 volunteers using magnetic resonance imaging to determine if such movement occurs with the spine in the neutral and flexed positions. The position of the conus medullaris in relation to the superior endplate of the L1 vertebra was determined. On spinal flexion, the conus medullaris moved cephalad in three subjects and caudad in three subjects, with no change in the remaining four. The median overall movement (95% CI [range]) was 0 mm (4 mm caudad to 1 mm cephalad [3 mm caudad to 1 mm cephalad]; p = 1.0). Whilst spinal flexion may facilitate needle insertion during dural puncture, it is unlikely to confer extra protection against spinal cord damage.

Pigmented villonodular synovitis of the hip mimicking soft-tissue sarcoma: a case report

Pigmented villonodular synovitis is a rare and benign but potentially locally aggressive disease that should be considered in younger patients who present with monoarticular joint symptoms and pathology. We present a 30-year-old Sudanese woman with a huge mass arising from the right hip joint. A multimodality radiological approach to investigation and diagnosis is demonstrated and discussed. Histopathological examination of the resected specimen confirmed the diagnosis of pigmented villonodular synovitis with the mass consisting of a proliferation of fibrohistiocytic cells, abundant haemosiderin, foamy histiocytes, and occasional giant cells. The patient made a good recovery, with mobility aided by arm crutches and a hip abduction brace.

Technique for measurement of fluorescence lifetime by use of stroboscopic excitation and continuous-wave detection

A study of the practicality a simple technique for obtaining time-domain information that uses continuous wave detection of fluorescence is presented. We show that this technique has potential for use in assays for which a change in the lifetime of an indicator occurs in reaction to an analyte, in fluorescence resonance energy transfer, for example, and could be particularly important when one is carrying out such measurements in the scaled-down environment of a lab on a chip (biochip). A rate-equation model is presented that allows an objective analysis to be made of the relative importance of the key measurement parameters: optical saturation of the fluorophore and period of the excitation pulse. An experimental demonstration of the technique that uses a cuvette-based analysis of a carbocyanine dye and for which the excitation source is a 650 nm wavelength, self-pulsing AlGaInP laser diode is compared with the model.

Treatment of Candida glabrata infection in immunosuppressed mice by using a combination of liposomal amphotericin B with caspofungin or micafungin

While Candida albicans remains the most common Candida isolate, Candida glabrata accounts for approximately 15 to 20% of all Candida infections in the United States. In this study we used immunosuppressed mice infected with C. glabrata to investigate the efficacy of liposomal amphotericin B alone or in combination with the echinocandin caspofungin or micafungin. For monotherapy, mice were given six daily doses of liposomal amphotericin B (3 to 20 mg/kg of body weight), caspofungin (1 to 5 mg/kg), or micafungin (2.5 to 10 mg/kg). With concomitant therapy, mice received liposomal amphotericin B (7.5 mg/kg) in addition to caspofungin (2.5 mg/kg) or micafungin (2.5 mg/kg) for 6 days. For sequential therapy, liposomal amphotericin B was administered on days 1 to 3 and caspofungin or micafungin was given on days 4 to 6; conversely, caspofungin or micafungin was administered on days 1 to 3 and liposomal amphotericin B was given on days 4 to 6. Efficacy was based on the number of CFU per gram of kidney 21 days postchallenge. Monotherapy with liposomal amphotericin B (7.5 to 20 mg/kg) was significantly more effective than no drug treatment (control group) (P < 0.05) and demonstrated a dose-dependent response, with 20 mg/kg lowering the CFU/g from 6.3 to 4.2 (significantly different from the value for the control group [P < 0.001]). Monotherapy with all echinocandin doses lowered the CFU/g from 6.0 to 6.4 to 2.7 to 3.3 (significantly different from the value for the control group [P < 0.001]) with no dose-dependent response. Complete clearance of infection could be achieved only when liposomal amphotericin B was given either concomitantly with caspofungin or micafungin or if liposomal amphotericin B was given sequentially with caspofungin. In conclusion, the combination of liposomal amphotericin B with an echinocandin markedly improved the therapeutic outcome in murine C. glabrata systemic infection.

Application of an automation system and a supervisory control and data acquisition (SCADA) system for the optimal operation of a membrane adsorption hybrid system

The application of automation and supervisory control and data acquisition (SCADA) systems to municipal water and wastewater treatment plants is rapidly increasing. However, the application of these systems is less frequent in the research and development phases of emerging treatment technologies used in these industries. This study involved the implementation of automation and a SCADA system to the submerged membrane adsorption hybrid system for use in a semi-pilot scale research project. An incremental approach was used in the development of the automation and SCADA systems, leading to the development of two new control systems. The first system developed involved closed loop control of the backwash initiation, based upon a pressure increase, leading to productivity improvements as the backwash is only activated when required, not at a fixed time. This system resulted in a 40% reduction in the number of backwashes required and also enabled optimised operations under unsteady concentrations of wastewater. The second system developed involved closed loop control of the backwash duration, whereby the backwash was terminated when the pressure reached a steady state. This system resulted in a reduction of the duration of the backwash of up to 25% and enabled optimised operations as the foulant build-up within the reactor increased.

Monitoring the ingestion of anti-tuberculosis drugs by simple non-invasive methods

This investigation retrospectively assessed inexpensive non-invasive qualitative methods to monitor the ingestion of anti-tuberculosis drugs isoniazid, rifampicin and rifapentine. Results showed that commercial test strips detected the isoniazid metabolites isonicotinic acid and isonicotinylglycine as efficiently as the isonicotinic acid method in 150 urine samples. The presence of rifamycins in urine samples (n=1085) was detected by microbiological assay techniques and the sensitivity compared to the n-butanol extraction colour test in 91 of these specimens. The proportions detected by the two methods were significantly different and the sensitivity of the n-butanol procedure was only 63.8% (95% CL 51.2-76.4%) as compared to that of the superior microbiological method. Final validation (n=691) showed that qualitative assays measure isoniazid and rifamycin ingestion with an efficiency similar to high-performance liquid chromatography. The qualitative procedures may therefore be valuable in clinical trials and in tuberculosis clinics to confirm drug ingestion.

Development of Nonsymmetrical 1,4-Disubstituted Anthraquinones That Are Potently Active against Cisplatin-Resistant Ovarian Cancer Cells

A novel series of 1,4-disubstituted aminoanthraquinones were prepared by ipso-displacement of 1,4-difluoro-5,8-dihydroxyanthraquinones by hydroxylated piperidinyl- or pyrrolidinylalkylamino side chains. One aminoanthraquinone (13) was further derivatized to a chloropropylamino analogue by treatment with triphenylphosphine-carbon tetrachloride. The compounds were evaluated in the A2780 ovarian cancer cell line and its cisplatin-resistant variants (A2780/cp70 and A2780/MCP1). The novel anthraquinones were shown to possess up to 5-fold increased potency against the cisplatin-resistant cells compared to the wild-type cells. Growth curve analysis of the hydroxyethylaminoanthraquinone 8 in the osteosarcoma cell line U-2 OS showed that the cell cycle is not frozen, rather there is a late cell cycle arrest consistent with the action of a DNA-damaging topoisomerase II inhibitor. Accumulative apoptotic events, using time lapse photography, indicate that 8 is capable of fully engaging cell cycle arrest pathways in G2 in the absence of early apoptotic commitment. 8 and its chloropropyl analogue 13 retained significant activity against human A2780/cp70 xenografted tumors in mice.

Quantitative structure-activity relationships of mutagenic activity from quantum topological descriptors: triazenes and halogenated hydroxyfuranones (mutagen-X) derivatives

The mutagenic activity of 23 triazenes and, in a different set, of 24 halogenated hydroxyfuranones (MX derivatives) is quantitatively related to new features of contemporary molecular wave functions. Nowadays affordable computers are powerful enough to rapidly generate geometry-optimised ab initio wave functions at HF/3-21G*, HF/6-31G* and B3LYP/6-311 + G(2d,p) level for all molecules. The bonds of a common molecular skeleton are described by their ab initio bond lengths and local properties provided by the theory of quantum chemical topology (QCT). The chemometric analysis involves two types: one to generate a statistically validated quantitative model, and one to isolate the active center. In the former a genetic algorithm (GA) selects bond descriptors in order to optimise the cross-validation error, q2, followed by a full partial least squares (PLS) analysis, which also yields randomisation statistics. In the latter type principal components (PCs) are constructed from the original bond descriptors and their variables important to the projection (VIPs) are plotted in a histogram. This analysis suggests a preferred mechanistic pathway for the initial hydroxylation of the triazenes, an issue that has remained ambiguous so far. In the case of the hydroxyfuranones the proposed method aids the elucidation of a mechanistic ambivalence.

The complications of Dupuytren's contracture surgery

PURPOSE

To determine the complication rate of a modified Skoog's technique in the surgical treatment of Dupuytren's contracture.

METHODS

A retrospective analysis was performed on 253 patients who had surgery by 1 surgeon using 1 technique with a mean follow-up period of 3.6 years. We studied the complication rate of the modified Skoog's procedure, relating it to a grading system for disease severity. A separate prospective long-term study was performed with an unselected cohort in which disease recurrence producing contracture was investigated prospectively in a group of 75 patients.

RESULTS

Complications occurred in 46 patients. Thirty-five patients had 1 complication and 11 patients had more than 1 complication. Intraoperative complications included 6 patients with nerve injury and 1 patient with an arterial injury. Early postoperative complications before wound healing included 5 patients with digital hematoma, 24 patients with wound infection, 6 patients with sympathetic dystrophy, and 6 patients with skin slough. Late postoperative complications included 3 patients with scar contraction and 2 patients with carpal tunnel syndrome. There were 3 non-hand-related complications: 1 urinary retention, 1 left ventricular failure, and 1 myocardial infarction. Recurrence of Dupuytren's disease occurred in 23 of 75 patients after a mean follow-up period of 9.4 years.

CONCLUSIONS

The complication rate increased with the severity of disease particularly if the proximal interphalangeal joint contracture was 60 degrees or more. There was no difference in the complication rate for patients who had surgery for primary or recurrent disease.

Assignment of the low-temperature fluorescence in oxygen-evolving photosystem II

Low-temperature absorption and fluorescence spectra of fully active cores and membrane-bound PS II preparations are compared. Detailed temperature dependence of fluorescence spectra between 5 and 70 K are presented as well as 1.7-K fluorescence line-narrowed (FLN) spectra of cores, confirming that PS II emission is composite. Spectra are compared to those reported for LHCII, CP43, CP47 and D1/D2/cytit b559 subunits of PS II. A combination of subunit spectra cannot account for emission of active PS II. The complex temperature dependence of PS II fluorescence is interpretable by noting that excitation transfer from CP43 and CP47 to the reaction centre is slow, and strongly dependent on the precise energy at which a 'slow-transfer' pigment in CP43 or CP47 is located within its inhomogeneous distribution. PS II fluorescence arises from CP43 and CP47 'slow-transfer' states, convolved by this dependence. At higher temperatures, thermally activated excitation transfer to the PS II charge-separating system bypasses such bottlenecks. As the charge-separating state of active PS II absorbs at >700 nm, PS II emission in the 680-700 nm region is unlikely to arise from reaction centre pigments. PS II emission at physiological temperatures is discussed in terms of these results.

Key cofactors of photosystem II cores from four organisms identified by 1.7-K absorption, CD and MCD

Active Photosystem II (PS II) cores were prepared from spinach, pea, Synechocystis PCC 6803, and Thermosynechococcus vulcanus, the latter of which has been structurally determined [Kamiya and Shen (2003) Proc Natl Acad Sci USA 100: 98-103]. Electrochromic shifts resulting from QA reduction by 1.7-K illumination were recorded, and the Qx and Qy absorption bands of the redox-active pheophytin a thus identified in the different organisms. The Qx transition is approximately 3 nm (100 cm-1) to higher energy in cyanobacteria than in the plants. The predominant Qy shift appears in the range 683-686 nm depending on species, and does not appear to have a systematic shift. Low-temperature absorption, circular dichroism (CD) and magnetic circular dichroism (MCD) spectra of the chlorophyll Qy region are very similar in spinach and pea, but vary in cyanobacteria. We assigned CP43 and CP47 trap-chlorophyll absorption features in all species, as well as a P680 transition. Each absorption identified has an area of one chlorophyll a. The MCD deficit, introduced previously for spinach as an indicator of P680 activity, occurs in the same spectral region and has the same area in all species, pointing to a robustness of this as a signature for P680. MCD and CD characteristics point towards a significant variance in P680 structure between cyanobacteria, thermophilic cyanobacteria, and higher plants.

Probing the lowest energy chlorophyll a states of photosystem II via selective spectroscopy: new insights on P680

We present the wavelength dependence of homogeneous holewidths of persistent spectral holes burnt in O2-evolving Photosystem II core complexes isolated from spinach, in the temperature range 2.5-8 K. The data supports the assignment that those chlorophylls which undergo persistent spectral hole-burning are specific CP43 and CP47-trap states that transfer their excitation energy to the reaction center. The lifetime-limited holewidths show that when PS II is in the S1(QA -) (closed) state, the CP43/CP47-trap states have excited-state lifetimes in the range from 70 to 270 ps. These lifetimes correspond to excitation transfer rates to the reaction center, and are far slower than required for models in which the PS II reaction center (P680) acts as a 'shallow-trap' for excitations. For wavelengths at which both traps absorb, the hole shape is clearly a composite of two Lorentzians, corresponding to hole-burning in both states simultaneously. The temperature dependence of the homogeneous holewidth does not follow the usual T1.3 dependence found in many chlorophyll-protein systems. Our data indicates T 2 temperature dependence, typically found in crystalline systems where the chromophore is coupled to localized phonon modes.

Efficacy and safety of pimobendan in canine heart failure caused by myxomatous mitral valve disease

OBJECTIVES

To evaluate the clinical efficacy and safety of pimobendan by comparing it with ramipril over a six-month period in dogs with mild to moderate heart failure (HF) caused by myxomatous mitral valve disease (MMVD).

METHODS

This was a prospective randomised, single-blind, parallel-group trial. Client-owned dogs (n = 43) with mild to moderate HF caused by MMVD were randomly assigned to one of two groups, which received either pimobendan (P dogs) or ramipril (R dogs) for six months. The outcome measures studied were: adverse HF outcome, defined as failure to complete the trial as a direct consequence of HF; maximum furosemide dose (mg/kg/day) administered during the study period; and any requirement for additional visits to the clinic as a direct consequence of HF.

RESULTS

Treatment with pimobendan was well tolerated compared with treatment with ramipril. P dogs were 25 per cent as likely as R dogs to have an adverse HF outcome (odds ratio 4.09, 95 per cent confidence interval 1.03 to 16.3, P = 0.046).

CLINICAL SIGNIFICANCE

R dogs had a higher overall score and thus may have had more advanced disease than P dogs at baseline (P = 0.04). These results should be interpreted cautiously but such a high odds ratio warrants further investigation.