The Adipose Organ Is a Unitary Structure in Mice and Humans

Obesity is the fifth leading cause of death worldwide. In mice and humans with obesity, the adipose organ undergoes remarkable morpho-functional alterations. The comprehension of the adipose organ function and organization is of paramount importance to understand its pathology and formulate future therapeutic strategies. In the present study, we performed anatomical dissections, magnetic resonance imaging, computed axial tomography and histological and immunohistochemical assessments of humans and mouse adipose tissues. We demonstrate that most of the two types of adipose tissues (white, WAT and brown, BAT) form a large unitary structure fulfilling all the requirements necessary to be considered as a true organ in both species. A detailed analysis of the gross anatomy of mouse adipose organs in different pathophysiological conditions (normal, cold, pregnancy, obesity) shows that the organ consists of a unitary structure composed of different tissues: WAT, BAT, and glands (pregnancy). Data from autoptic dissection of 8 cadavers, 2 females and 6 males (Age: 37.5 ± 9.7, BMI: 23 ± 2.7 kg/m²) and from detailed digital dissection of 4 digitalized cadavers, 2 females and 2 males (Age: 39 ± 14.2 years, BMI: 22.8 ± 4.3 kg/m²) confirmed the mixed (WAT and BAT) composition and the unitary structure of the adipose organ also in humans. Considering the remarkable endocrine roles of WAT and BAT, the definition of the endocrine adipose organ would be even more appropriate in mice and humans.

Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

A programme to support resilience and clinical excellence in inherited cardiac conditions nurses based in the hospital and charity sector during the COVID-19 pandemic and beyond

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The Burdett Trust for Nursing

Background

The COVID-19 pandemic affected health care systems profoundly. Inherited cardiac condition (ICC) specialist nurses were redeployed to intensive care or acute settings which either left services with no nurse or a single nurse manning a normally busy service (Bueser 2020). An exponential rise in patients reaching out to patient support charities was seen (Charity Today 2020) and at the peak of the pandemic, nurses based at an ICC charity dealt with 599 inquiries which was a 328% increase in activity. The toll on the mental health of nurses during the pandemic is well documented and programmes have been suggested to address this which includes peer support and psychological support by clinical psychologists

Purpose

The aim was to develop and strengthen collaborations between ICC specialist nurses in a tertiary hospital and those working in the community charity sector; and provide peer and psychological support to enable consistent high quality patient care.

Methods

The project was based on Wenger’s (1999) Communities of Practice (COP) framework model of situational learning, collaboration among peers, working to a common purpose. To develop the counselling aspect, a psychotherapist led a scoping exercise with the group. The 4Rs Skilled Helper Programme (SHP) of reflective learning, supervision and continuing professional development was then adapted as a bespoke programme - combining 30 hours of formal counselling, communication and reflective learning skills with equal attention to the normative, formative and restorative components of support and development needed to ensure practitioner health and wellbeing and the safety and quality of patient care

Results

Nine ICC nurses from a tertiary hospital and 3 from the charity sector participated in the project. Nine nurses undertook the tailored 4RS SHP course, adapting Egan's 3 stage problem-solving, decision-making and opportunity development framework as the vehicle for personalised, psychosocial, time-sensitive decision-making and informed consent for patients, and for the identification of support and development strategies that represent the 'best fit' for both clients and practitioners in their particular social and organisational circumstances. Counselling supervision is ongoing on a whole group, team and individual basis and provides opportunities to discuss collaborations, gain support for challenging clinical cases and work situations; and promoting psychological well-being.

Conclusions

The COP established through this project alongside the development of a bespoke counselling course and psychological supervision is an exemplar of how nurses can be empowered to continue to provide excellent care despite challenging circumstances. The 4RS SHP course also specifically addresses the competency needs for ICC nurses as move towards a genomics-driven, personalised health care delivery model.

The use of portable XRF as a forensic geoscience non-destructive trace evidence tool for environmental and criminal investigations

Hand-held, portable X-Ray fluorescence instruments (pXRF) provide a means of rapid, in-situ chemical characterisation that has considerable application as a rapid trace evidence characterisation tool in forensic geoscience. This study presents both a control test study which demonstrates optimisation of the data collection process, alongside a range of individual forensic case studies, including heavy metal contamination, conflict archaeology, forensic soil characterisation, and verification of human remains, which together validate the technique and provide some comparison between field-based and laboratory-based pXRF applications. Results highlight the time-efficiency and cost-effectiveness of in-situ, field-based pXRF analyses for material characterisation when compared with other trace evidence methods. Analytical precision of various analytes during in-situ analysis was sufficient to demonstrate considerable application of field-based pXRF as a tool for rapid identification of specific areas of interest to be further investigated. Laboratory-based pXRF analyses yielded greater accuracy which could provide an efficient compromise between field-based pXRF and traditional laboratory-based analytical techniques (e.g. WD-XRF, ICP-MS). Further studies should collect more advanced datasets in more diverse locations to further validate the techniques capability to rapidly conduct geochemical surveys in a range of environments.

94 What are the Components of Care Offered By POPS (Perioperative Medicine for Older People Undergoing Surgery) Services Across the UK; A Targeted National Survey

Introduction

Over the past five years the number of Perioperative medicine for Older People undergoing Surgery (POPS) services in the UK has increased.1,2 This expansion has occurred in response to the needs of an older, multimorbid surgical population with drivers for change coming from national reports and audit results. Different models of care have emerged; this study aimed to describe in detail the surgical specialties, components of care and staffing as delivered by current UK POPS services.3,4

Methods

An electronic ten-question survey was sent to 31 acute NHS trusts, purposively selected from the British Geriatrics Society POPS network and previous survey respondents.

Results

Responses were received from 23 of 31 trusts (71%) with key results in Table 1. Eighty-three percent of respondents provided a geriatric-consult service, 13% a shared-care model and 4% had ceased their service due to inadequate funding. The surgical specialties covered included; general surgery (18/23), vascular (12/23) and other including urology, trauma, gynaecology (9/23). Team structures varied with 26% of geriatricians working independently and only 23% having dedicated allied health support. Forty-one percent of services were surgically funded, 36% medically funded and 23% from both directorates.

Conclusions

The predominant model of care remains a geriatric-consult service. The evidenced-based ‘shared-care’ model previously only in operation at a large teaching hospital has now been replicated in two smaller hospitals. A previously described model involving patients transitioning from surgical to geriatric medicine teams was not seen in practice in this study.4 In line with the NHS’ vision of rationalising and scaling innovation, this survey highlights the growing need to establish a standardised POPS model across the UK.

References

1. Partridge J. Age and Ageing. 2014; 43: 721–4.

2. Joughlin A. Age and Ageing. 2019; 48: 458–62.

3. Shipway D. Reviews in Clinical Gerontology. 2014; 24: 78–92.

4. Howie S. Clinical Medicine. 2018; 19: 189.

Dopamine increases NMDA-stimulated calcium flux in striatopallidal neurons through a matrix metalloproteinase-dependent mechanism

Dopamine (DA) is a potent neuromodulator known to influence glutamatergic transmission in striatal medium spiny neurons (MSNs). It acts on D1- and D2-like DA receptors that are expressed on two distinct subpopulations. MSNs projecting to the substantia nigra express D1 receptors (D1Rs), while those projecting to the lateral globus pallidus express D2 receptors (D2Rs). D1R signalling in particular can increase excitatory transmission through varied protein kinase A-dependent, cell-autonomous pathways. Mechanisms by which D1R signalling could increase excitatory transmission in D2R-bearing MSNs have been relatively less explored. Herein, the possibility is considered that D1R agonists increase levels of soluble factors that subsequently influence N-methyl-D-aspartate (NMDA)-stimulated calcium flux in D2R neurons. This study focuses on matrix metalloproteinases (MMPs) and MMP-generated integrin binding ligands, important soluble effectors of glutamatergic transmission that may be elevated in the setting of excess DA. It was observed that DA and a D1R agonist, SKF81297, increase MMP activity in extracts from striatal slices, as determined by cleavage of the substrate β-dystroglycan. Using mice engineered to express the calcium indicator GCaMP3 in striatopallidal D2R-bearing neurons, it was also observed that SKF81297 pretreatment of slices (60 min) potentiates NMDA-stimulated calcium increases in this subpopulation. Effects are diminished by pretreatment with an antagonist of MMP activity or an inhibitor of integrin-dependent signalling. Together, results suggest that DA signalling can increase excitatory transmission in D2R neurons through an MMP-dependent mechanism. Future studies may be warranted to determine whether D1R-stimulated MMP-dependent processes contribute to behaviours in which increased activity in striatopallidal MSNs plays a role.

A mathematical model of the mechanical link between shortening of the cardiomyocytes and systolic deformation of the left ventricular myocardium

BACKGROUND

Left ventricular myocytes are arranged in a complex three-dimensional mesh. Since all myocytes contract approximately to the same degree, mechanisms must exist to enable force transfer from each of these onto the framework as a whole, despite the transmural differences in deformation strain. This process has hitherto not been clarified in detail.

OBJECTIVE

To present a geometrical model that establishes a mechanical link between the three-dimensional architecture and the function of the left ventricular myocardium.

METHODS

The left ventricular equator was modeled as a cylindrical tube of deformable but incompressible material, composed of virtual cardiomyocytes with known diastolic helical and transmural angles. By imposing reference circumferential, longitudinal, and torsional strains onto the model, we created a three-dimensional deformation field to calculate passive shortening of the myocyte surrogates. We tested two diastolic architectures: 1) a simple model with longitudinal myocyte surrogates in the endo- and epicardium, and circular ones in the midwall, and 2) a more accurate architecture, with progressive helical angle distribution varying from -60° in the epicardium to 60° in the endocardium, with or without torsion and transmural cardiomyocyte angulation.

RESULTS

The simple model caused great transmural unevenness in cardiomyocyte shortening; longitudinal surrogates shortened by 15% at all depths equal to the imposed longitudinal strain, whereas circular surrogates exhibited a maximum shortening of 23.0%. The accurate model exhibited a smooth transmural distribution of cardiomyocyte shortening, with a mean (range) of 17.0 (13.2-20.8)%. Torsion caused a shortening of 17.0 (15.2-18.9)% and transmural angulation caused a shortening of 15.2 (12.4-18.2)%. Combining the effects of transmural angulation and torsion caused a change of 15.2 (13.2-16.5)%.

CONCLUSION

A continuous transmural distribution of the helical angle is obligatory for smooth shortening of the cardiomyocytes, but a combination of torsional and transmural angulation changes is necessary to execute systolic mural thickening whilst keeping shortening of the cardiomyocytes within its physiological range.

Soluble ICAM-5, a product of activity dependent proteolysis, increases mEPSC frequency and dendritic expression of GluA1

Matrix metalloproteinases (MMPs) are zinc dependent endopeptidases that can be released from neurons in an activity dependent manner to play a role in varied forms of learning and memory. MMP inhibitors impair hippocampal long term potentiation (LTP), spatial memory, and behavioral correlates of drug addiction. Since MMPs are thought to influence LTP through a β₁ integrin dependent mechanism, it has been suggested that these enzymes cleave specific substrates to generate integrin binding ligands. In previously published work, we have shown that neuronal activity stimulates rapid MMP dependent shedding of intercellular adhesion molecule-5 (ICAM-5), a synaptic adhesion molecule expressed on dendrites of the telencephalon. We have also shown that the ICAM-5 ectodomain can interact with β₁ integrins to stimulate integrin dependent phosphorylation of cofilin, an event that occurs with dendritic spine maturation and LTP. In the current study, we investigate the potential for the ICAM-5 ectodomain to stimulate changes in α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptor (AMPAR) dependent glutamatergic transmission. Single cell recordings show that the ICAM-5 ectodomain stimulates an increase in the frequency, but not the amplitude, of AMPA mini excitatory post synaptic currents (mEPSCs). With biotinylation and precipitation assays, we also show that the ICAM-5 ectodomain stimulates an increase in membrane levels of GluA1, but not GluA2, AMPAR subunits. In addition, we observe an ICAM-5 associated increase in GluA1 phosphorylation at serine 845. Concomitantly, ICAM-5 affects an increase in GluA1 surface staining along dendrites without affecting an increase in dendritic spine number. Together these data are consistent with the possibility that soluble ICAM-5 increases glutamatergic transmission and that post-synaptic changes, including increased phosphorylation and dendritic insertion of GluA1, could contribute. We suggest that future studies are warranted to determine whether ICAM-5 is one of a select group of synaptic CAMs whose shedding contributes to MMP dependent effects on learning and memory.

Total Anomalous Pulmonary Venous Connection

Background—

Late mortality after repair of total anomalous pulmonary venous connection is frequently associated with pulmonary venous obstruction (PVO). We aimed to describe the morphological spectrum of total anomalous pulmonary venous connection and identify risk factors for death and postoperative PVO.

Methods and Results—

We conducted a retrospective, international, collaborative, population-based study involving all 19 pediatric cardiac centers in the United Kingdom, Ireland, and Sweden. All infants with total anomalous pulmonary venous connection born between 1998 and 2004 were identified. Cases with functionally univentricular circulations or atrial isomerism were excluded. All available data and imaging were reviewed. Of 422 live-born cases, 205 (48.6%) had supracardiac, 110 (26.1%) had infracardiac, 67 (15.9%) had cardiac, and 37 (8.8%) had mixed connections. There were 2 cases (0.5%) of common pulmonary vein atresia. Some patients had extremely hypoplastic veins or, rarely, discrete stenosis of the individual veins. Sixty (14.2%) had associated cardiac anomalies. Sixteen died before intervention. Three-year survival for surgically treated patients was 85.2% (95% confidence interval 81.3% to 88.4%). Risk factors for death in multivariable analysis comprised earlier age at surgery, hypoplastic/stenotic pulmonary veins, associated complex cardiac lesions, postoperative pulmonary hypertension, and postoperative PVO. Sixty (14.8%) of the 406 patients undergoing total anomalous pulmonary venous connection repair had postoperative PVO that required reintervention. Three-year survival after initial surgery for patients with postoperative PVO was 58.7% (95% confidence interval 46.2% to 69.2%). Risk factors for postoperative PVO comprised preoperative hypoplastic/stenotic pulmonary veins and absence of a common confluence.

Conclusions—

Preoperative clinical and morphological features are important risk factors for postoperative PVO and survival.

Vitamin D receptor gene polymorphism is associated with reduced disability in multiple sclerosis

Ultraviolet radiation (UVR) may contribute to multiple sclerosis (MS) outcome by a mechanism involving vitamin D and the vitamin D receptor (VDR). In 512 patients with MS duration of 10 or more years, we studied the association of VDR single nucleotide polymorphisms (A/G1229, C/G3444, G/A3944, CC20965, CC30056, F/f30875, C/T48200, T/t65013) with outcome or disability. ff30875 frequency was lower in cases with EDSS ≥ 6.0 than with scores < 6.0 (odds ratio = 0.38, 95% CI = 0.20–0.70). The association of ff30875 with outcome was not mediated by cumulative exposure to UVR as assessed by questionnaire; low exposure (odds ratio = 0.42, 95% CI = 0.14–1.34) and high exposure (odds ratio = 0.34, 95% CI = 0.16–0.73).

Structure of oxidized bismuth nanoclusters

Synchrotron X-ray diffraction has determined that β-Bi2O3 is the dominant oxide phase covering hexagonal bismuth nanoclusters produced in an inert gas aggregation source. Simulated Debye–Scherrer patterns have indicated that the oxide is 20 ± 5 Å thick on average, at the surface of 320 ± 40 Å diameter clusters. A Williamson–Hall analysis of the peak broadening was used to measure the non-uniform strain in clusters. The oxidized clusters were in −0.11 ± 0.06% uniform compressive strain compared with other clusters without oxides detectable by X-ray diffraction which only have a small tensile uniform strain. High-resolution transmission electron microscopy (HRTEM) and multislice image simulations indicated a β-Bi2O3 thickness of 20–50 Å. The HRTEM micrographs show the relative orientation between the oxide and the cluster core.

Post-embryonic expression of C. elegans microRNAs belonging to the lin-4 and let-7 families in the hypodermis and the reproductive system

MicroRNAs (miRNAs) are regulatory molecules that negatively control gene expression by binding to complementary sequences on target mRNAs. The most thoroughly characterized miRNAs, lin-4 and let-7, direct cell fate determination during the larval transitions in C. elegans and act as key regulators of temporal gene expression. lin-4 and let-7 are founding members of two distinct families of miRNA genes sharing strong sequence homology primarily in the 5' end of the mature miRNAs. In this report, we characterize the temporal and spatial expression patterns of lin-4 and let-7 family members using northern blot analysis and mir::gfp fusion studies. Our results show that lin-4 and let-7 homologues possess distinct temporal and spatial expression patterns during nematode development and that known heterochronic genes regulate their expression. We find that certain lin-4 and let-7 family members display overlapping expression patterns in the hypodermis and the reproductive system, suggesting that combinations of miRNAs from across families may control common developmental events.

Radiation dose reduction without compromise of image quality in cardiac angiography and intervention with the use of a flat panel detector without an antiscatter grid

OBJECTIVE

To test the hypothesis that replacing the antiscatter grid with an air gap will reduce patient radiation exposure without significant compromise of image quality.

METHODS

457 patients having either uncomplicated diagnostic studies or a single vessel angioplasty (percutaneous transluminal coronary angioplasty (PTCA)) on a flat plate system (GE Innova) were studied. For two months their total dose-area product score was recorded on standard gridded images and then for two months on images made with the grid out, with an air gap used to reduce scatter. Detector magnification was reduced one step when an air gap was used to achieve the same final image size. A sample set of studies was reviewed blind by five observers, who scored sharpness and contrast on a non-linear scale.

RESULTS

The average dose-area product was significantly reduced, both in the diagnostic group (n = 276), from a mean (SD) of 26.2 (14.7) Gy.cm2 with the grid in to 16.1 (12) Gy.cm2 with the grid out (p = 0.01), and in the PTCA group (n = 181), from 48.2 (36.2) to 37 (27.5) (p = 0.01). The mean image quality scores of the gridless cohort were not significantly different from those of the gridded cohort.

CONCLUSION

With the use of a flat plate detector, air gap gridless angiography reduces the radiation dose to the patient and, in consequence, to the operator without significantly affecting image quality. It is proposed that gridless imaging should be the default technique for adults and children and in most installations.

Coronary calcification score: the coronary-risk impact factor

CONTEXT

Identification of asymptomatic high-risk individuals is integral to current policies for preventing coronary heart disease, but existing methods of estimating risk lack sensitivity. To overcome this limitation increasing use is being made of non-invasive methods to detect subclinical coronary artery disease--eg, computed tomography (CT) to scan for coronary artery calcification. The location and extent of calcification correlate closely with pathological and angiographic abnormalities, but whether such calcification predicts clinical events, especially in younger individuals, is equivocal. Most data on coronary calcification have been obtained with electron-beam CT, but recently multislice CT, which is more versatile, less expensive, and available in most large hospitals, has been increasingly used.

STARTING POINT

Leslee Shaw and colleagues (Radiology 2003; 228: 826-33) showed that the coronary calcification score predicted total mortality within subsets of patients classified at low, intermediate, or high risk according to Framingham criteria. In a cohort of over 10000 individuals, 5-year risk-adjusted survival was 95% when the score was over 1000 compared with 99% for scores of 10 or less. These results agree with other recent studies showing strong correlations between coronary calcification and coronary heart disease events. WHERE NEXT? The increasing use of multislice CT scanners should generate more data for comparison with those obtained from electron-beam CT. Radiation dose, which is higher with multislice than with electron-beam procedures, needs to be reduced, and calcification in scans needs to be quantified more accurately than with existing computer-based analyses. Further studies are needed to establish the predictive power of the coronary calcification score for clinical events and the effects of therapeutic intervention on both these outcomes. It would also be worth investigating the relation between coronary calcification and risk factors not quantified in Framingham-based estimates, including familial and racial predisposition to premature coronary heart disease.

Aortic-left ventricular discontinuity of noninfectious origin

The existence of a cavity of noninfectious origin between the annulus of the ascending aorta and the left ventricle is described. Aortic-left ventricular discontinuity occurred as a late complication of aortic valve replacement in an octogenarian. A patient with severe symptomatic aortic valve stenosis underwent aortic valve replacement and aortic root enlargement into the noncoronary sinus with pericardial tissue. Four months after her valve surgery the patient presented with shortness of breath. Angiocardiography and transoesophageal echocardiography revealed a complex, irregular pouch at the right coronary cusp side of the valve with paravalvular leakage back into the left ventricular outflow tract. Reoperation was performed, the disconnection between the aortic annulus and the left ventricle was repaired and the valve was replaced. The aortic-left ventricular discontinuity did not involve the area where aortic root enlargement was performed. No evidence of infection was found and the most likely cause of the reported complication is mechanical in nature.

The role of the PTPRC (CD45) mutation in the development of multiple sclerosis in the North West region of the United Kingdom

BACKGROUND

A point mutation in protein tyrosine phosphatase receptor, type c polypeptide (PTPRC) has been associated with familial multiple sclerosis. This CG mutation at position 77 of exon 4 results in altered expression of CD45 isoforms on immune cells.

OBJECTIVE

To study the incidence of PTPRC mutations in subjects with multiple sclerosis in the North West region of the United Kingdom.

METHODS

Affected and unaffected subjects from five pedigrees with familial multiple sclerosis, 330 non-familial cases of multiple sclerosis, and 197 controls were studied. Genomic DNA was amplified using CD45IE34 and CD45IE44 primers, digested with Mspl, and run on an agarose gel. Polymerase chain reaction products were sequenced to exclude any other mutations.

RESULTS

No PTPRC exon 4 genomic mutations were seen in any of the five families. In the non-familial cases the incidence of mutation was 4.1% in 197 controls and 5.1% in 330 multiple sclerosis patients. No significant association was found in this study with this mutation and disease susceptibility, sex, or an extended disability scale score of < 5.5.

CONCLUSIONS

This candidate does not appear to influence the development of familial multiple sclerosis in this population. The negative result could arise from a type II error owing to the number of families and non-familial cases screened. Alternatively it might suggest that the contribution of the PTPRC mutation depends upon the genetic background.

Left ventricular function during support with an asynchronous pulsatile left ventricular assist device

BACKGROUND

Left ventricular assist devices (LVADs) are frequently used to maintain patients with severe heart failure until heart transplantation becomes possible. Some patients may experience recovery of LV function during such support. Therefore, it is essential to be able to monitor changes in LV function in this setting.

METHODS

We studied LV function in 10 patients (median age 34 years, 9 male) who had LVADs implanted because of severe heart failure due to dilated cardiomyopathy a median of 4 months previously. Median pre-implant ejection fraction was 27% and all patients had been on maximal medical therapy, including intravenous inotropic support, prior to insertion of the LVAD.

RESULTS

During LVAD support there were cyclical variations in LV dimensions, fractional shortening (FS) and transmitral flow, related to changes in the phase relationship of the LV and the LVAD. The "best" FS occurred when LV systole coincided with device filling and the "worst" FS when LV systole coincided with device ejection. Median FS with the pump switched off was 18% (10% to 32%). Pump-off FS was significantly greater than the "worst" FS with the pump on (5%, p = 0.002), and similar to the "best" pump-on FS (19%, p = NS).

CONCLUSIONS

LV function could be studied echocardiographically during LV support and brief periods of interruption in support. Function varied according to the phase relationship of the LV and LVAD. The "best" FS measured during LVAD support was more closely related to the FS with the device switched off than the "worst" pump on FS. The "best" pump-on LV function is therefore most representative of intrinsic LV performance and can be used as a guide to recovery and the potential need for pump-off studies.

Tuning of the product spectrum of vanillyl-alcohol oxidase by medium engineering

The flavoenzyme vanillyl-alcohol oxidase (VAO) catalyzes the conversion of 4-alkylphenols through the initial formation of p-quinone methide intermediates. These electrophilic species are stereospecifically attacked by water to yield (R)-1-(4'-hydroxyphenyl)alcohols or rearranged in a competing reaction to 1-(4'-hydroxyphenyl)alkenes. Here, we show that the product spectrum of VAO can be controlled by medium engineering. When the enzymatic conversion of 4-propylphenol was performed in organic solvent, the concentration of the alcohol decreased and the concentration of the cis-alkene, but not the trans-alkene, increased. This change in selectivity occurred in both toluene and acetonitrile and was dependent on the water activity of the reaction medium. A similar shift in alcohol/cis-alkene product ratio was observed when the VAO-mediated conversion of 4-propylphenol was performed in the presence of monovalent anions that bind specifically near the enzyme active site.

Supercritical fluids are superior media for catalysis by cross-linked enzyme microcrystals of subtilisin Carlsberg

We report on the performance of cross-linked enzyme microcrystals (CLECs) of subtilisin Carlsberg in supercritical fluids (SC-fluids). The catalytic activity of CLECs in SC-ethane was found to be 2- to 10-fold greater than in hexane under the same conditions, using CLECs dried by propanol washing. Air-dried CLECs and lyophilized powders showed much lower activities, reflecting the same hydration hysteresis effects as in organic solvents. Reaction rates were much lower in SC-CO(2), especially at higher water activity, probably as a result of acid-base effects of carbonic acid on the enzyme.