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Biomedical subjects

Alex Brown

Publications and source records attributed to Alex Brown.

At least 19 recordsLinked to original sources
PubMed2026

Structured robotic colorectal training in a non-tertiary NHS hospital: a 502-case consecutive cohort implementation study.

Robotic-assisted colorectal surgery has expanded rapidly across NHS practice in the UK. Structured unit-wide training pathways are essential for safe technology adoption, yet published outcome data from non-tertiary hospitals remain limited. This study describes the implementation and feasibility of a unit-wide robotic colorectal program at a high-volume non-tertiary hospital, reporting outcomes across 502 consecutive resections performed by eight consultant surgeons and presenting these in the context of nationally published benchmarks. A retrospective cohort study of 502 consecutive robotic colorectal resections performed at York Teaching Hospital between May 2022 and December 2025. Eight consultant surgeons (A-H) participated in a structured four-phase training pathway incorporating simulation training, proctored cases, complexity-based case progression, and formal credentialing. Primary outcomes were 30-day mortality, unplanned return to theatre (RTT), and anastomotic leak (AL). Anastomotic leak was calculated using only patients who underwent anastomosis as the denominator. Procedure-stratified and individual surgeon outcomes with 95% confidence intervals were reported. Risk-adjusted cumulative sum (RA-CUSUM) analysis was performed to evaluate learning curves. Outcomes are presented descriptively alongside nationally published reference data; no formal statistical comparison against national benchmarks was performed. 502 robotic colorectal resections were performed. Mean patient age was 70.0 ± 11.3 years; 58.4% were male. Median ASA grade was III. The indication was malignancy in 89.2% of cases. Length of stay was non-normally distributed and is therefore reported using median and interquartile range in the revised analysis. Key outcomes: - 30-day mortality: 1.0% (5/502; 95% CI 0.4-2.3%) - Unplanned return to theatre (RTT): 5.2% (26/502; 95% CI 3.6-7.5%) - Anastomotic leak (AL): 3.3% (15/450; 95% CI 2.0-5.5%; denominator = patients with anastomosis) - 30-day unplanned readmission: 5.0% (25/502; 95% CI 3.4-7.2%) - Conversion to open surgery: 3.6% (18/502; 95% CI 2.3-5.6%) - Lymph node yield ≥12: 91.3% of cancer resections - R0 resection rate: 95.1% of cancer resections All primary outcomes fell within or below the published reference ranges used for descriptive context. RA-CUSUM trajectories were heterogeneous: no surgeon crossed the predefined upper control limit, but several curves showed later upward movement. Accordingly, the analysis is interpreted as safety surveillance rather than evidence of uniform performance improvement. RA-CUSUM monitoring showed that no surgeon crossed the predefined upper control limit; however, heterogeneous trajectories precluded a claim of uniform performance improvement.

Humans↗
PubMed2024

Translation of culturally and contextually informed diabetes training for Aboriginal primary health care providers on Aboriginal client outcomes: Protocol of a cluster randomized crossover trial of effectiveness.

BACKGROUND: Indigenous populations globally have significantly high rates of type 2 diabetes compared to their non-Indigenous counterparts. This study aims to implement and evaluate the effectiveness of a culturally and contextually informed Aboriginal Diabetes Workforce Training Program on Aboriginal primary health care workforce knowledge, attitude, confidence, skill and practice relating to diabetes care. METHODS: A Cluster Randomised Crossover Control Trial with two arms (Group A and Group B) will be conducted with Aboriginal primary health care services in South Australia. These services primarily provide primary health care to Aboriginal and Torres Strait Islander people. All healthcare service sites will be randomised into groups A and B to receive the training program. The training program consists of three components: 1) Peer support network, 2) E-Learning modules and 3) onsite support. Aboriginal Health Workers of participating sites will be invited to participate in the monthly online peer support network and all chronic disease staff are eligible to participate in the E-Learning modules and onsite support. The Peer Support Network runs for the entirety of the study, 17 months. Training components 2 and 3 occur simultaneously and are 2.5 months in length, with a six-month washout period between the two randomised groups undertaking the training. All primary outcomes of the study relate to diabetes management in a primary health care settings and measure participants' knowledge, attitude, confidence, practice and skills. These will be collected at seven time points across the entire study. Secondary outcomes measure satisfaction of the peer support network using a survey, interviews to understand enablers and barriers to participation, health service systems characteristics through focus groups, and medical record review to ascertain diabetes patients' care received and their clinical outcomes up to 12 months post training intervention. DISCUSSION: The findings will explore the effectiveness of the training program on Aboriginal primary health care provider knowledge, attitude, confidence, skill and practice relating to diabetes care. The final findings will be published in 2027. TRIAL REGISTRATION: The study was prospectively registered in The Australian New Zealand Clinical Trials Registry (ANZCTR), with registration number ACTRN12623000749606 at ANZCTR - Registration. Universal Trial Number (UTN) U1111-1283-5257.

Humans↗
PubMed2006

LMSD: LIPID MAPS structure database.

The LIPID MAPS Structure Database (LMSD) is a relational database encompassing structures and annotations of biologically relevant lipids. Structures of lipids in the database come from four sources: (i) LIPID MAPS Consortium's core laboratories and partners; (ii) lipids identified by LIPID MAPS experiments; (iii) computationally generated structures for appropriate lipid classes; (iv) biologically relevant lipids manually curated from LIPID BANK, LIPIDAT and other public sources. All the lipid structures in LMSD are drawn in a consistent fashion. In addition to a classification-based retrieval of lipids, users can search LMSD using either text-based or structure-based search options. The text-based search implementation supports data retrieval by any combination of these data fields: LIPID MAPS ID, systematic or common name, mass, formula, category, main class, and subclass data fields. The structure-based search, in conjunction with optional data fields, provides the capability to perform a substructure search or exact match for the structure drawn by the user. Search results, in addition to structure and annotations, also include relevant links to external databases. The LMSD is publicly available at www.lipidmaps.org/data/structure/.

Databases, Factual↗
PubMed2006

Mastery, perceived stress and health-related behaviour in northeast Arnhem Land: a cross-sectional study.

BACKGROUND: Indigenous peoples in Australia are disadvantaged on all markers of health and social status across the life course. Psychosocial factors are implicated in the aetiology of chronic diseases and in pathways underpinning social health disparities. Minimal research has investigated psychosocial factors and health in Indigenous peoples. This study evaluated associations between mastery, perceived stress, and health-related behaviour for a remote Indigenous population in Australia. METHODS: Complete data on mastery (the degree to which individuals feel in control of their lives), perceived stress, physical activity, and fruit and vegetable consumption were obtained for 177 participants in a community-based chronic disease risk factor survey. Psychosocial questionnaires were completed as an option during community screening (response rate = 61.9%). Extensive consultation facilitated the cross-cultural adaptation of measures. RESULTS: Mastery was inversely correlated with perceived stress measures (p < 0.009): recent stress, r = -0.47; chronic stress, r = -0.41; and youth stress, r = -0.30. Relationships between mastery and behaviour varied according to age group (<25 or > or =25 years) for physical activity (p = 0.001) and vegetable consumption (p = 0.005). Individuals aged > or =25 years engaging in < or =2 bouts of physical activity/week had lower mastery than individuals engaging in > or =3 bouts/week, with means (95% CI) of 14.8 (13.7-15.8) and 17.1 (15.3-19.0), respectively (p = 0.026). Individuals aged > or =25 years eating vegetables < or =3 times/week had lower mastery than those eating vegetables > or =4 times/week (p = 0.009) [means 14.7 (13.8-15.5) and 17.3 (15.5-19.1), respectively]. Individuals <25 years engaging in < or =2 bouts of physical activity/week had greater mastery than individuals engaging in > or =3 bouts/week (p = 0.022) [means 17.2 (15.2-19.2) and 13.8 (11.9-15.7), respectively]. For men > or =25 years and women > or =15 years, mastery was inversely related to age (p < 0.002). Men <25 years had less mastery than women of equivalent age (p = 0.001) [means 13.4 (12.1-14.7) and 17.5 (15.3-19.8), respectively]. CONCLUSION: Consistent with previous research, this study provides additional support for a link between mastery and health-related behaviour, and extends evidence of this association to a remote Indigenous population. Mastery's association with perceived stress, its age-specific association with health behaviour, and findings of low mastery amongst young men, highlights a need for life course research accounting for contextual factors affecting Indigenous peoples.

Journal Article↗
PubMed2006

Practical challenges of conducting research into rheumatic fever in remote Aboriginal communities.

Before embarking on an epidemiological study of acute rheumatic fever in remote Aboriginal communities, researchers engaged in the processes of community consultation, consent and household enrollment. Community expectations and time constraints are not necessarily those of the funding bodies, and a considerable investment of time and local engagement was required before the project proceeded with local support. The remoteness of the communities, harsh climate and limited infrastructure made working conditions difficult. Nevertheless, the study was completed and the results are being returned to the local councils and households. The research team continues to maintain its relationship with each study community.

Community Participation↗
PubMed2006

Photodissociation of HBr. 1. Electronic structure, photodissociation dynamics, and vector correlation coefficients.

Ab initio potential energy curves, transition dipole moments, and spin-orbit coupling matrix elements are computed for HBr. These are then used, within the framework of time-dependent quantum-mechanical wave-packet calculations, to study the photodissociation dynamics of the molecule. Total and partial integral cross sections, the branching fraction for the formation of excited-state bromine atoms Br(2P(1/2)), and the lowest order anisotropy parameters, beta, for both ground and excited-state bromine are calculated as a function of photolysis energy and compared to experimental and theoretical data determined previously. Higher order anisotropy parameters are computed for the first time for HBr and compared to recent experimental measurements. A new expression for the Re[a1(3) (parallel, perpendicular)] parameter describing coherent parallel and perpendicular production of ground-state bromine in terms of the dynamical functions is given. Although good agreement is obtained between the theoretical predictions and the experimental measurements, the discrepancies are analyzed to establish how improvements might be achieved. Insight is obtained into the nonadiabatic dynamics by comparing the results of diabatic and fully adiabatic calculations.

Anisotropy↗
PubMed2006

Pulse shaping for optimal control of molecular processes.

In this paper, a new method is proposed to design optimized control fields with desired temporal and/or spectral properties. The method is based on penalizing the difference between an optimized field obtained from an iterative scheme and a reference field with desired temporal and/or spectral properties. Compared with the standard optimal control theory, the current method allows a simple, experimentally accessible field be found on the fly; while compared with parameter space searching optimization, the iterative nature of this method allows automatic exploration of the intrinsic mechanism of the population transfer. The method is illustrated by examing the optimal control of vibrational excitation of the Cl-O bond with both temporally and spectrally restricted pulses.

Journal Article↗
PubMed2006

Quantum computing based on vibrational eigenstates: pulse area theorem analysis.

In a recent paper [D. Babikov, J. Chem. Phys. 121, 7577 (2004)], quantum optimal control theory was applied to analyze the accuracy of quantum gates in a quantum computer based on molecular vibrational eigenstates. The effects of the anharmonicity parameter of the molecule, the target time of the pulse, and the penalty function on the accuracy of the qubit transformations were investigated. We demonstrate that the effects of all the molecular and laser-pulse parameters can be explained utilizing the analytical pulse area theorem, which originates from the standard two-level model. Moreover, by analyzing the difference between the optimal control theory results and those obtained using the pulse area theorem, it is shown that extremely high quantum gate fidelity can be achieved for a qubit system based on vibrational eigenstates.

Comment↗
PubMed2005

Photodissociation of HI and DI: testing models for electronic structure via polarization of atomic photofragments.

The photodissociation dynamics of HI and DI are examined using time-dependent wave-packet techniques. The orientation and alignment parameters aQ(K) (p) are determined as a function of photolysis energy for the resulting ground-state I(2P(3/2)) and excited-state I(2P(1/2)) atoms. The aQ(K) (p) parameters describe the coherent and incoherent contributions to the angular momentum distributions from the A 1pi(1), a 3pi(1), and t 3sigma(1) electronic states accessed by perpendicular excitation and the a 3pi(0+) state accessed by a parallel transition. The outcomes of the dynamics based on both shifted ab initio results and three empirical models for the potential-energy curves and transition dipole moments are compared and contrasted. It is demonstrated that experimental measurement of the aQ(K) (p) parameters for the excitation from the vibrational ground state (upsilon=0) would be able to distinguish between the available models for the HI potential-energy curves and transition dipole moments. The differences between the aQ(K) (p) parameters for the excitation from upsilon=0 stand in sharp contrast to the scalar properties, i.e., total cross section and I* branching fraction, which require experimental measurement of photodissociation from excited vibrational states (upsilon>0) to distinguish between the models.

Journal Article↗
PubMed2005

Photodissociation of HI and DI: polarization of atomic photofragments.

The complete angular momentum distributions and vector correlation coefficients (orientation and alignment) of ground state I((2)P(32)) and excited state I((2)P(12)) atoms resulting from the photodissociation of HI have been computed as a function of photolysis energy. The orientation and alignment parameters a(Q) ((K))(p) that describe the coherent and incoherent contributions to the angular momentum distributions from the multiple electronic states accessed by parallel and perpendicular transitions are determined using a time-dependent wave packet treatment of the dissociation dynamics. The dynamics are based on potential energy curves and transition dipole moments that have been reported previously [R. J. LeRoy, G. T. Kraemer, and S. Manzhos, J. Chem. Phys. 117, 9353 (2002)] and used to successfully model the scalar (total cross section and branching fraction) and lowest order vector (anisotropy parameter beta) properties of the photodissociation. Predictions of the a(Q) ((K))(p), parameters for the isotopically substituted species DI are reported and contrasted to the analogous HI results. The resulting polarization for the corresponding H/D partners are also determined and demonstrate that both H and D atoms produced can be highly spin polarized. Comparison of these predictions for HI and DI with experimental measurement will provide the most stringent test of the current model for the electronic structure and the interpretation of the dissociation based on noncoupled excited state dynamics.

Journal Article↗
PubMed2005

Ab initio potential energy surfaces, total absorption cross sections, and product quantum state distributions for the low-lying electronic states of N(2)O.

Adiabatic potential energy surfaces for the six lowest singlet electronic states of N(2)O (X (1)A('), 2 (1)A('), 3 (1)A('), 1 (1)A("), 2 (1)A(") and 3 (1)A(")) have been computed using an ab initio multireference configuration interaction (MRCI) method and a large orbital basis set (aug-cc-pVQZ). The potential energy surfaces display several symmetry related and some nonsymmetry related conical intersections. Total photodissociation cross sections and product rotational state distributions have been calculated for the first ultraviolet absorption band of the system using the adiabatic ab initio potential energy and transition dipole moment surfaces corresponding to the lowest three excited electronic states. In the Franck-Condon region the potential energy curves corresponding to these three states lie very close in energy and they all contribute to the absorption cross section in the first ultraviolet band. The total angular momentum is treated correctly in both the initial and final states. The total photodissociation spectra and product rotational distributions are determined for N(2)O initially in its ground vibrational state (0,0,0) and in the vibrationally excited (0,1,0) (bending) state. The resulting total absorption spectra are in good quantitative agreement with the experimental results over the region of the first ultraviolet absorption band, from 150 to 220 nm. All of the lowest three electronically excited states [(1)Sigma(-)(1 (1)A(")), (1)Delta(2 (1)A(')), and (1)Delta(2 (1)A("))] have zero transition dipole moments from the ground state [(1)Sigma(+)(1 (1)A('))] in its equilibrium linear configuration. The absorption becomes possible only through the bending motion of the molecule. The (1)Delta(2 (1)A('))<--X (1)Sigma(+)((1)A(')) absorption dominates the absorption cross section with absorption to the other two electronic states contributing to the shape and diffuse structure of the band. It is suggested that absorption to the bound (1)Delta(2 (1)A(")) state makes an important contribution to the experimentally observed diffuse structure in the first ultraviolet absorption band. The predicted product rotational quantum state distribution at 203 nm agrees well with experimental observations.

Journal Article↗
PubMed2005

Calcium, phosphorus and vitamin D disorders in uremia.

BACKGROUND: Alterations in calcium, phosphate (P) and vitamin D metabolism play a critical role in the development of secondary hyperparathyroidism (SH), parathyroid hyperplasia and soft tissue and vascular calcification. METHODOLOGY: Studies were performed in uremic dogs and rats fed a low and high P diet over a period of 1-4 months. In addition, in vitro studies were performed in normal parathyroid glands incubated in culture media containing 0.2 mM P (low) or 2.0 mM P (high). RESULTS: Uremic rats maintained on a low P diet did not develop SH or parathyroid hyperplasia. There was an enhancement of p21, the suppressor of the cell cycle, in these parathyroid glands. Opposite results were obtained using a high P diet. There was an enhancement of transforming growth factor-alpha and epidermal growth factor receptor, known enhancers of cell proliferation. In vitro studies demonstrated the direct effect of P on parathyroid hormone secretion. CONCLUSIONS: Early dietary P restriction prevents the development of SH and parathyroid hyperplasia. If dietary P restriction is applied to rats with established SH, there is a significant amelioration of SH and parathyroid hyperplasia. In addition, control of serum P in uremic patients is crucial in the prevention of vascular calcification.

Animals↗
PubMed2005

Indigenous male health disadvantage--linking the heart and mind.

BACKGROUND: Aboriginal men experience unacceptably high morbidity and mortality rates for almost all medical conditions. Heart disease and depression in particular are common, inter-linked, and potentially amendable to interventions delivered through primary care. OBJECTIVE: This article aims to raise awareness of mental illness and heart disease in Aboriginal men, to explore the links between these disease groups, and to encourage general practitioners to do all they can to help reduce morbidity and mortality, in particular through active secondary prevention. DISCUSSION: It would be simplistic to think that these problems can be adequately addressed merely through improved general practice services, but improved recognition of illness by GPs, improved accessibility and acceptability of health services, active follow up and management of depression and heart disease, and ongoing engagement with communities is likely to improve the current situation.

Australia↗
PubMed2004

Normal mode analysis using the driven molecular dynamics method. II. An application to biological macromolecules.

The driven molecular-dynamics (DMD) method, recently proposed by Bowman, Zhang, and Brown [J. Chem. Phys. 119, 646 (2003)], has been implemented into the TINKER molecular modeling program package. The DMD method yields frequencies and normal modes without evaluation of the Hessian matrix. It employs an external harmonic driving term that can be used to scan the spectrum and determine resonant absorptions. The molecular motions, induced by driving at resonant frequencies, correspond to the normal-mode vibrations. In the current work we apply the method to a 20-residue protein, Trp-cage, that has been reported by Neidigh, Fesinmeyer, and Andersen [Nature Struct. Biol. 9, 425 (2002)]. The structural and dynamical properties of this molecule, such as B-factors, root-mean square fluctuations, anisotropies, vibrational entropy, and cross-correlations coefficients, are calculated using the DMD method. The results are in very good agreement with ones calculated using standard normal-mode analysis method. Thus, the DMD method provides a viable alternative to the standard Hessian-based method and has considerable potential for the study of large systems, where the Hessian-based method is not feasible.

Algorithms↗
PubMed2004

Quantum and classical studies of vibrational motion of CH5+ on a global potential energy surface obtained from a novel ab initio direct dynamics approach.

We report a full dimensional, ab initio based potential energy surface for CH(5) (+). The ab initio electronic energies and gradients are obtained in direct-dynamics calculations using second-order Møller-Plesset perturbation theory with the correlation consistent polarized valence triple zeta basis. The potential energy and the dipole moment surfaces are fit using novel procedures that ensure the full permutational symmetry of the system. The fitted potential energy surface is tested by comparing it against additional electronic energy calculations and by comparing normal mode frequencies at the three lowest-lying stationary points obtained from the fit against ab initio ones. Well-converged diffusion Monte Carlo zero-point energies, rotational constants, and projections along the CH and HH bond lengths and the tunneling coordinates are presented and compared with the corresponding harmonic oscillator and standard classical molecular dynamics ones. The delocalization of the wave function is analyzed through comparison of the CH(5) (+) distributions with those obtained when all of the hydrogen atoms are replaced by (2)H and (3)H. The classical dipole correlation function is examined as a function of the total energy. This provides a further probe of the delocalization of CH(5) (+).

Journal Article↗
PubMed2004

Long-term surveillance of cefotaxime and piperacillin-tazobactam prescribing and incidence of Clostridium difficile diarrhoea.

OBJECTIVES: We followed the effects of changes to a new antibiotic policy favouring a ureidopenicillin as opposed to a third-generation cephalosporin on the long-term incidence of Clostridium difficile diarrhoea (CDD) and antibiotic utilization in a large Elderly Medicine Unit. PATIENTS AND METHODS: In 1999, piperacillin-tazobactam was added to the formulary in Elderly Medicine and its use promoted in preference to cefotaxime. Following review and feedback to clinicians of surveillance data, cefotaxime prescribing was actively restricted during 2000-2001. An audit of prescriber adherence to antibiotic policy was carried out by reviewing the records of 159 patients during February-April 2001. In December 2001, due to manufacturer production problems, supply of piperacillin-tazobactam was stopped. We performed standardized period prevalence surveillance (February-April) allowing comparisons of antibiotic utilization and CDD incidence during the 5 year study period (1998-2002). RESULTS: CDD incidence did not change significantly (P>0.1) during 1998-1999 despite a marked increase in piperacillin-tazobactam prescribing. However, when cefotaxime prescribing was curtailed in 2001, CDD rates decreased (in four of five wards) and overall by 52% (P=0.008). When piperacillin-tazobactam became unavailable in 2002, despite advice to the contrary cefotaxime prescribing rose five-fold, and CDD rates increased in four of five wards and by 232% (P<0.01) overall. Adherence to antibiotic policy introduced in 2000 was good (81% accordance); 94%, 88% and 73% of patients with cellulitis, urinary tract and respiratory tract infection, respectively, received appropriate antibiotics. CONCLUSIONS: Long-term prescribing of piperacillin-tazobactam in Elderly Medicine in preference to cefotaxime is associated with reduced rates of CDD. However, unless cephalosporin prescribing is curtailed, the beneficial effects on CDD rates may be missed. This is one of few studies to document adverse effects due to loss of antibiotic supply.

Aged↗
PubMed2003

Spin-polarized hydrogen atoms from molecular photodissociation.

The production of spin-polarized hydrogen atoms from the photodissociation of hydrogen chloride with circularly polarized 193-nanometer light is inferred from the measurement of the complete angular momentum distributions of ground state Cl(2P3/2)and excited state Cl(2P1/2)cofragments by slice imaging. The experimentally measured and ab initio predicted a q(k) (p)parameters, which describe the single-surface and multiple-surface-interference contributions to the angular momentum distributions, are in excellent agreement. For laser pulses longer than about 0.7 ns, the polarization of the electron and the proton are both 36%.

Journal Article↗