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1.
Diabet Med ; 37(12): 2027-2034, 2020 12.
Article in English | MEDLINE | ID: mdl-32592220

ABSTRACT

AIMS: To describe the use and validation of a survey tool to elicit the opinion of hospital pharmacists and medicines safety officers in the UK regarding the perceived effectiveness of strategies to improve insulin prescribing safety in hospitals. METHODS: One respondent from each participating organization completed the survey on behalf of the main acute hospital in their trust (n = 92). A five-point Likert scale was used to determine opinion on how effective 22 different interventions were at promoting insulin safety at the respondent's trust. The tool, the Perception of Effectiveness of Prescribing Safety Interventions for Insulin (PEPSII) questionnaire, underwent content validity testing. The reliability was estimated using Cronbach's alpha (α). RESULTS: The PEPSII questionnaire demonstrated good reliability (α = 0.867). Outreach team review and mandatory insulin education were the highest-scoring interventions; the insulin passport was amongst the lowest scoring interventions. Most interventions were considered more effective by trusts using them compared to those who didn't, except for self-administration policies, electronic prescribing and the insulin passport. CONCLUSIONS: The perceived effectiveness of a variety of insulin prescribing safety strategies in UK hospitals was described by leveraging a purposely developed survey tool. The results describe current levels of support for recommended interventions, and may facilitate the direction of both local and national insulin prescribing safety improvement efforts.


Subject(s)
Attitude of Health Personnel , Diabetes Mellitus/drug therapy , Hospitals , Hypoglycemic Agents/therapeutic use , Insulin/therapeutic use , Medication Errors/prevention & control , Pharmacists , Decision Support Systems, Clinical , Education, Medical , Humans , Hypoglycemia/chemically induced , Hypoglycemia/prevention & control , Organizational Policy , Patient Safety , Surveys and Questionnaires , United Kingdom
2.
Diabet Med ; 37(7): 1176-1184, 2020 07.
Article in English | MEDLINE | ID: mdl-31845373

ABSTRACT

AIM: To describe insulin prescribing practice in National Health Service hospitals in the UK and the current use of interventions and strategies to reduce insulin prescribing errors. METHODS: We sent a cross-sectional questionnaire to chief pharmacists in all National Health Service hospital trusts in the UK in January 2019. Questions concerned the use and functionality of electronic and paper systems used to prescribe subcutaneous insulin, along with features and interventions designed to reduce insulin prescribing errors. RESULTS: Ninety-five hospital trusts responded (54%). Electronic prescribing of insulin was reported in 40% of hospitals, most of which were teaching hospitals in England. We found a wide variation in the functionality of both electronic prescribing and paper-based systems to enable the safe prescribing of insulin for inpatients. The availability of specialist diabetes pharmacists to support the safe prescribing of insulin was low (29%), but was positively associated with the use of a greater number of insulin prescribing error reduction strategies (P=0.002). The use of specific interventions to improve insulin prescribing quality (e.g. self-administration policies) varied greatly between respondent hospitals. CONCLUSIONS: There is potential to optimize the functionality of both electronic and paper-based prescribing systems to improve the safe prescribing of insulin in hospitals in the UK. The wide variation in the use of insulin error reduction strategies may be improved by the availability of specialist diabetes pharmacists who can support the implementation of insulin-prescribing interventions.


Subject(s)
Electronic Prescribing/statistics & numerical data , Hospitals , Hypoglycemic Agents/therapeutic use , Insulin/therapeutic use , Medication Errors/prevention & control , Pharmacists , Pharmacy Service, Hospital/methods , Practice Patterns, Physicians' , Cross-Sectional Studies , Hospitals, Teaching , Humans , Injections, Subcutaneous , State Medicine , Surveys and Questionnaires , United Kingdom
3.
Diabet Med ; 36(8): 948-960, 2019 08.
Article in English | MEDLINE | ID: mdl-31050037

ABSTRACT

AIM: To conduct a systematic review of literature to identify interventions that are effective in improving insulin prescribing for people with diabetes in the hospital setting. METHODS: Computerized bibliographic databases were searched for studies published in English that described the effectiveness of interventions to improve insulin prescribing within the hospital setting. Studies were eligible for inclusion if they reported data that compared insulin prescribing practice after an intervention or compared with a control group. Studies were not excluded on the basis of publication date, geographical location or risk of bias assessment. RESULTS: We identified 35 studies for inclusion in the review, including two cluster randomized controlled trials, two cohort studies, and 31 uncontrolled before-after studies. Studies reported a variety of interventions that aimed to increase insulin prescribing accuracy or completeness or decrease the use of discouraged subcutaneous sliding scale insulin regimens. Differences in definition of insulin prescribing error, terminology and common practice based on geographical location was evident, and quality issues with respect to study design and reporting somewhat limited the interpretation of conclusions. CONCLUSIONS: Implementing strategies that are sensitive to local context and designed to increase adherence to insulin prescribing guidelines are associated with a reduction in prescribing errors. Future implementation should build on effective approaches including multifaceted interventions involving multiple stakeholders at various institutional levels. Future studies in insulin prescribing errors would benefit from the use of standardized approaches, terminology and outcome measures to enable greater comparison.


Subject(s)
Diabetes Mellitus/drug therapy , Hospitalization , Hypoglycemic Agents/therapeutic use , Insulin/therapeutic use , Practice Patterns, Physicians'/standards , Drug Prescriptions/standards , Guideline Adherence , Humans , Practice Guidelines as Topic , Quality Improvement
4.
Cancer Lett ; 439: 14-23, 2018 12 28.
Article in English | MEDLINE | ID: mdl-30240587

ABSTRACT

RNA interference (RNAi) therapy is an emerging class of biopharmaceutical that has immense potential in cancer medicine. RNAi medicines are based on synthetic oligonucleotides that can suppress a target protein in tumour cells with high specificity. This review explores the attractive prospect of using RNAi as a radiosensitiser by targeting the DNA damage response. There are a multitude of molecular targets involved in the detection and repair of DNA damage that are suitable for this purpose. Recent developments in delivery technologies such nanoparticle carriers and conjugation strategies have allowed RNAi therapeutics to enter clinical trials in the treatment of cancer. With further progress, RNAi targeting of the DNA damage response may hold great promise in guiding radiation oncology into the era of precision medicine.


Subject(s)
DNA Damage , Neoplasms/radiotherapy , RNA Interference , Radiation Tolerance/genetics , Drug Delivery Systems/methods , Gene Expression Regulation, Neoplastic/genetics , Gene Expression Regulation, Neoplastic/radiation effects , Humans , Nanoparticles , Neoplasms/genetics , RNA, Small Interfering/administration & dosage , RNA, Small Interfering/genetics
5.
J Chem Phys ; 148(13): 134312, 2018 Apr 07.
Article in English | MEDLINE | ID: mdl-29626854

ABSTRACT

Time and polarization-resolved stimulated emission depletion (STED) measurements are used to investigate excited state evolution following the two-photon excitation of enhanced green fluorescent protein (EGFP). We employ a new approach for the accurate STED measurement of the hitherto unmeasured degree of hexadecapolar transition dipole moment alignment α40 present at a given excitation-depletion (pump-dump) pulse separation. Time-resolved polarized fluorescence measurements as a function of pump-dump delay reveal the time evolution of α40 to be considerably more rapid than predicted for isotropic rotational diffusion in EGFP. Additional depolarization by homo-Förster resonance energy transfer is investigated for both α20 (quadrupolar) and α40 transition dipole alignments. These results point to the utility of higher order dipole correlation measurements in the investigation of resonance energy transfer processes.


Subject(s)
Green Fluorescent Proteins/chemistry , Green Fluorescent Proteins/radiation effects , Photons , Fluorescence Polarization , Fluorescence Resonance Energy Transfer , Light , Models, Chemical , Thermodynamics
6.
J Chem Phys ; 148(13): 134311, 2018 Apr 07.
Article in English | MEDLINE | ID: mdl-29626864

ABSTRACT

In this work, we present a complete theoretical description of the excited state order created by two-photon photoselection from an isotropic ground state; this encompasses both the conventionally measured quadrupolar (K = 2) and the "hidden" degree of hexadecapolar (K = 4) transition dipole alignment, their dependence on the two-photon transition tensor and emission transition dipole moment orientation. Linearly and circularly polarized two-photon absorption (TPA) and time-resolved single- and two-photon fluorescence anisotropy measurements are used to determine the structure of the transition tensor in the deprotonated form of enhanced green fluorescent protein. For excitation wavelengths between 800 nm and 900 nm, TPA is best described by a single element, almost completely diagonal, two-dimensional (planar) transition tensor whose principal axis is collinear to that of the single-photon S0 → S1 transition moment. These observations are in accordance with assignments of the near-infrared two-photon absorption band in fluorescent proteins to a vibronically enhanced S0 → S1 transition.


Subject(s)
Green Fluorescent Proteins/chemistry , Green Fluorescent Proteins/radiation effects , Photons , Fluorescence Polarization , Infrared Rays , Models, Chemical
7.
Exp Physiol ; 102(12): 1635-1646, 2017 12 01.
Article in English | MEDLINE | ID: mdl-28901662

ABSTRACT

NEW FINDINGS: What is the central question of this study? Endothelium-dependent flow-mediated dilatation (FMD) is impaired during acute (60 min) exposure to moderate hypoxia. We examined whether FMD is impaired to the same degree during exposure to milder hypoxia. Additionally, we assessed whether smooth muscle vasodilatory capacity [glyceryl trinitrate (GTN)-induced dilatation] is impaired during acute hypoxic exposure. What is the main finding and its importance? A graded impairment in FMD and GTN-induced dilatation was evident during acute (≤60 min) exposure to mild and moderate hypoxia. This study is the first to document these graded impairments, and provides rationale to examine the relationship between graded increases in sympathetic nerve activity with hypoxia on FMD and GTN-induced dilatation. Endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent dilatation [induced with glyceryl trinitrate (GTN)] are impaired at high altitude (5050 m), and FMD is impaired after acute exposure (<60 min) to normobaric hypoxia equivalent to ∼5050 m (inspired oxygen fraction âˆ¼0.11). Whether GTN-induced dilatation is impaired acutely and whether FMD is impaired during milder hypoxia are unknown. Therefore, we assessed brachial FMD at baseline and after 30 min of mild (end-tidal PO2 74 ± 2 mmHg) and moderate (end-tidal PO2 50 ± 3 mmHg) normobaric hypoxia (n = 12) or normoxia (time-control trial; n = 10). We also assessed GTN-induced dilatation after the hypoxic FMD tests and in normoxia on a separate control day (n = 8). Compared with the normoxic baseline, reductions during mild and moderate hypoxic exposure were evident in FMD (mild versus moderate, -1.2 ± 1.1 versus -3.1 ± 1.7%; P = 0.01) and GTN-induced dilatation (-2.1 ± 1.0 versus -4.2 ± 2.0%; P = 0.01); the declines in FMD and GTN-induced dilatation were greater during moderate hypoxia (P < 0.01). When allometrically corrected for baseline diameter and FMD shear rate under the curve, FMD was attenuated in both conditions (mild versus moderate, 0.6 ± 0.9 versus 0.8 ± 0.7%; P ≤ 0.01). After 30 min of normoxic time control, FMD was reduced (-0.6 ± 0.3%; P = 0.02). In summary, there was a graded impairment in FMD during mild and moderate hypoxic exposure, which appears to be influenced by shear patterns and incremental decline in smooth muscle vasodilator capacity (impaired GTN-induced dilatation). Our findings from the normoxic control study suggest the decline in FMD in acute hypoxia also appears to be influenced by 30 min of supine rest/inactivity.


Subject(s)
Endothelium, Vascular/physiopathology , Hypoxia/physiopathology , Muscle, Smooth, Vascular/physiopathology , Vasodilation , Acute Disease , Adult , Blood Flow Velocity , Brachial Artery/drug effects , Brachial Artery/physiopathology , British Columbia , Female , Healthy Volunteers , Humans , Male , Muscle, Smooth, Vascular/drug effects , Nitroglycerin/pharmacology , Regional Blood Flow , Time Factors , Vasodilation/drug effects , Vasodilator Agents/pharmacology , Young Adult
8.
Anal Chem ; 86(21): 10591-9, 2014 Nov 04.
Article in English | MEDLINE | ID: mdl-25260090

ABSTRACT

We introduce a fast computational method for feature selection that facilitates the accurate spectral analysis of a chemical species of interest in the presence of overlapping uncorrelated variance. Using a genetic algorithm in a data-driven approach, our method assigns predictors according to a template determined to minimize prediction variance in a calibration space. This template-oriented genetic algorithm (TOGA) efficiently establishes features of greatest significance and determines their optimal combination. We demonstrate the efficacy of TOGA using an elementary model system in which we seek to quantify a target monosaccharide in mixtures containing other sugars added in random amounts. The results establish TOGA as an effective and reliable technique for isolating signature spectra of targeted substances in complex mixtures.


Subject(s)
Algorithms , Monosaccharides/analysis , Spectrum Analysis, Raman/methods , Calibration , Carbohydrates/analysis , Monosaccharides/isolation & purification , Multivariate Analysis
9.
Acta Physiol (Oxf) ; 206(2): 98-108, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22574769

ABSTRACT

AIM: To assess whether, under conditions permitting full evaporation, body heat storage during physical activity measured by partitional calorimetry would be lower with warm relative to cold fluid ingestion because of a disproportionate increase in evaporative heat loss potential relative to internal heat transfer with the ingested fluid. METHODS: Nine males cycled at 50% VO(2max) for 75 min at 23.6 ± 0.6 °C and 23 ± 11% RH while consuming water of either 1.5 °C, 10 °C, 37 °C or 50 °C in four 3.2 mL kg(-1) boluses. The water was administered 5 min before and 15, 30 and 45 min following the onset of exercise. RESULTS: No differences in metabolic heat production, sensible or respiratory heat losses (all P > 0.05) were observed between fluid temperatures. However, while the increased internal heat loss with cold fluid ingestion was paralleled by similar reductions in evaporative heat loss potential at the skin (E(sk) ) with 10 °C (P = 0.08) and 1.5 °C (P = 0.55) fluid, the increased heat load with warm (50 °C) fluid ingestion was accompanied by a significantly greater E(sk) (P = 0.04). The resultant calorimetric heat storage was lower with 50 °C water ingestion in comparison to 1.5 °C, 10 °C and 37 °C (all P < 0.05). In contrast, heat storage derived conventionally using thermometry yielded higher values following 50 °C fluid ingestion compared to 1.5 °C (P = 0.025). CONCLUSION: Under conditions permitting full sweat evaporation, body heat storage is lower with warm water ingestion, likely because of disproportionate modulations in sweat output arising from warm-sensitive thermosensors in the esophagus/stomach. Local temperature changes of the rectum following fluid ingestion exacerbate the previously identified error of thermometric heat storage estimations.


Subject(s)
Bicycling , Body Temperature Regulation , Drinking , Exercise , Hot Temperature , Sweating , Analysis of Variance , Calorimetry , Cold Temperature , Heart Rate , Humans , Male , Models, Biological , Oxygen Consumption , Skin Temperature , Thermogenesis , Time Factors , Young Adult
10.
Solid State Nucl Magn Reson ; 42: 26-32, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22336040

ABSTRACT

The effectiveness of two different selective inversion methods is investigated to determine timescales of Li ion mobility in paramagnetic Li intercalation materials. The first method is 1D exchange spectroscopy, which employs a 90°-τ(1)-90° sequence for selective inversion of a Li resonance undergoing site exchange. The experiment is most easily applied when the first delay period, τ(1), is set to the frequency difference between two resonances undergoing ion exchange. This enables the determination of ion hopping timescales for single exchange pair systems only. To measure ion dynamics in systems having more than one exchange process, a second selective inversion method was tested on two paramagnetic Li intercalation materials. This second technique, replaces the 90°-τ(1)-90° portion of 1D EXSY with a long, selective shaped pulse (SP). Two paramagnetic solid-state materials, which are both cathode materials for lithion ion batteries, were chosen as model compounds to test the effectiveness of both the selective inversion methods. The first compound, Li(2)VPO(4)F, was chosen as it hosts two Li sites with 1-exchange process. The second model compound is a 3-site, 3-exchange process system, Li(2)VOPO(4). For the 2-site material, Li(2)VPO(4)F, the timescales of the single A-B exchange process were found to be within error of one another regardless of the inversion method. For the 3 Li-site material Li(2)VOPO(4), the three exchange processes, AB, BC, and AC, were found to be on the millisecond timescale as revealed using the SP method. These timescales were determined over a variable temperature range where activation energies extended from 0.6 ± 0.1 eV up to 0.9 ± 0.2 eV.


Subject(s)
Electric Power Supplies , Electrodes , Lithium/chemistry , Magnetic Resonance Spectroscopy/methods , Materials Testing/methods , Energy Transfer , Ions
11.
Biochem Soc Trans ; 31(Pt 5): 1047-51, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14505477

ABSTRACT

A new approach to time-resolved fluorescence spectroscopy based on stimulated emission depletion (STED) of two-photon excited states is presented. Combined with time-resolved detection, STED can circumvent orientational averaging constraints and spontaneous emission selection rules inherent in all conventional techniques. Applications of STED to the study of molecular probe dynamics are presented, together with studies of STED dynamics in a new push-push two-photon chromophore.


Subject(s)
Photons , Spectrometry, Fluorescence/methods , Humans , Models, Chemical , Time Factors
12.
J Neurotrauma ; 18(5): 499-511, 2001 May.
Article in English | MEDLINE | ID: mdl-11393253

ABSTRACT

In this investigation, the relationships between stretch and both morphological and electrophysiological signs of axonal injury were examined in the guinea pig optic nerve stretch model. Additionally, the relationship between axonal morphology and electrophysiological impairment was assessed. Axonal injury was produced in vivo by elongating the guinea pig optic nerve between 0 and 8 mm (Ntotal = 70). Morphological damage was detected using neurofilament immunohistochemistry (SMI 32). Electrophysiological impairment was determined using changes in visual evoked potentials (VEPs) measured prior to injury, every 5 min for 40 min following injury, and at sacrifice (72 h). All nerves subjected to ocular displacements greater than 6 mm demonstrated axonal swellings and retraction bulbs, while nerves subjected to displacements below 4 mm did not show any signs of morphological injury. Planned comparisons of latency shifts of the N35 peak in the VEPs showed that ocular displacements greater than 5 mm produced electrophysiological impairment that was significantly different from sham animals. Logit analysis demonstrated that less stretch was required to elicit electrophysiological changes (5.5 mm) than morphological signs of damage (6.8 mm). Moreover, Student t tests indicated that the mean latency shift measured in animals exhibiting morphological injury was significantly greater than that calculated from animals lacking morphological injury (p < 0.01). These data show that distinct mechanical thresholds exist for both morphological and electrophysiological damage to the white matter. In a larger context, the distinct injury thresholds presented in the report will aid in the biomechanical assessment of animate models of head injury, as well as assist in extending these findings to predict the conditions that cause white matter injury in humans.


Subject(s)
Diffuse Axonal Injury/pathology , Diffuse Axonal Injury/physiopathology , Optic Nerve Injuries/pathology , Optic Nerve Injuries/physiopathology , Animals , Biomechanical Phenomena , Electrophysiology , Evoked Potentials, Visual/physiology , Guinea Pigs , Male
13.
Ann Emerg Med ; 37(1): 5-12, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11145764

ABSTRACT

STUDY OBJECTIVE: The efficacy of a shock waveform for external defibrillation depends on the waveform characteristics. Recently, design principles based on cardiac electrophysiology have been developed to determine optimal waveform characteristics. The objective of this clinical trial was to evaluate the efficacy of principles-based monophasic and biphasic waveforms for external defibrillation. METHODS: A prospective, randomized, blinded, multicenter study of 118 patients undergoing electrophysiologic testing or receiving an implantable defibrillator was conducted. Ventricular fibrillation was induced, and defibrillation was attempted in each patient with a biphasic and a monophasic waveform. Patients were randomly placed into 2 groups: group 1 received shocks of escalating energy, and group 2 received only high-energy shocks. RESULTS: The biphasic waveform achieved a first-shock success rate of 100% in group 1 (95% confidence interval [CI] 95.1% to 100%) and group 2 (95% CI 94.6% to 100%), with average delivered energies of 201+/-17 J and 295+/-28 J, respectively. The monophasic waveform demonstrated a 96.7% (95% CI 89.1% to 100%) first-shock success rate and average delivered energy of 215+/-12 J for group 1 and a 98.2% (95% CI 91.7% to 100%) first-shock success rate and average delivered energy of 352+/-13 J for group 2. CONCLUSION: Using principles of electrophysiology, it is possible to design both biphasic and monophasic waveforms for external defibrillation that achieve a high first-shock efficacy.


Subject(s)
Electric Countershock/methods , Ventricular Fibrillation/therapy , Aged , Confidence Intervals , Defibrillators, Implantable , Female , Humans , Intraoperative Period , Male , Middle Aged , Prospective Studies , Treatment Outcome , United States
14.
J Biomech Eng ; 122(6): 615-22, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11192383

ABSTRACT

In vivo, tissue-level, mechanical thresholds for axonal injury were determined by comparing morphological injury and electrophysiological impairment to estimated tissue strain in an in vivo model of axonal injury. Axonal injury was produced by dynamically stretching the right optic nerve of an adult male guinea pig to one of seven levels of ocular displacement (Nlevel = 10; Ntotal = 70). Morphological injury was detected with neurofilament immunohistochemical staining (NF68, SM132). Simultaneously, functional injury was determined by the magnitude of the latency shift of the N35 peak of the visual evoked potentials (VEPs) recorded before and after stretch. A companion set of in situ experiments (Nlevel = 5) was used to determine the empirical relationship between the applied ocular displacement and the magnitude of optic nerve stretch. Logistic regression analysis, combined with sensitivity and specificity measures and receiver operating characteristic (ROC) curves were used to predict strain thresholds for axonal injury. From this analysis, we determined three Lagrangian strain-based thresholds for morphological damage to white matter. The liberal threshold, intended to minimize the detection of false positives, was a strain of 0.34, and the conservative threshold strain that minimized the false negative rate was 0.14. The optimal threshold strain criterion that balanced the specificity and sensitivity measures was 0.21. Similar comparisons for electrophysiological impairment produced liberal, conservative, and optimal strain thresholds of 0.28, 0.13, and 0.18, respectively. With these threshold data, it is now possible to predict more accurately the conditions that cause axonal injury in human white matter.


Subject(s)
Optic Nerve Injuries/pathology , Optic Nerve Injuries/physiopathology , Wounds, Nonpenetrating/pathology , Wounds, Nonpenetrating/physiopathology , Analysis of Variance , Animals , Axons/pathology , Axons/physiology , Disease Models, Animal , Evoked Potentials, Visual , Guinea Pigs , Male , ROC Curve , Reaction Time , Regression Analysis , Sensitivity and Specificity , Stress, Mechanical
15.
Biophys J ; 76(4): 2198-207, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10096914

ABSTRACT

Ligand-dependent structural changes in serum albumin are suggested to underlie its role in physiological solute transport and receptor-mediated cellular selection. Evidence of ligand-induced (oleic acid) structural changes in serum albumin are shown in both time-resolved and steady-state fluorescence quenching and anisotropy measurements of tryptophan 214 (Trp214). These studies were augmented with column chromatography separations. It was found that both the steady-state and time-resolved Stern-Volmer collisional quenching studies of Trp214 with acrylamide pointed to the existence of an oleate-dependent structural transformation. The bimolecular quenching rate constant of defatted human serum albumin, 1.96 x 10(9) M-1 s-1, decreased to 0.94 x 10(9) M-1 s-1 after incubation with oleic acid (9:1). Furthermore, Stern-Volmer quenching studies following fractionation of the structural forms by hydrophobic interaction chromatography were in accordance with this interpretation. Time-resolved fluorescence anisotropy measurements of the Trp214 residue yielded information of motion within the protein together with the whole protein molecule. Characteristic changes in these motions were observed after the binding of oleate to albumin. The addition of oleate was accompanied by an increase in the rotational diffusion time of the albumin molecule from approximately 22 to 33.6 ns. Within the body of the protein, however, the rotational diffusion time for Trp214 exhibited a slight decrease from 191 to 182 ps and was accompanied by a decrease in the extent of the angular motion of Trp214, indicating a transition after oleate binding to a more spatially restricted but less viscous environment.


Subject(s)
Serum Albumin/chemistry , Acrylamide , Biophysical Phenomena , Biophysics , Chromatography, Gel , Fluorescence Polarization , Humans , In Vitro Techniques , Iodides , Kinetics , Ligands , Oleic Acid , Protein Conformation , Spectrometry, Fluorescence , Tryptophan/chemistry
16.
J Neuropathol Exp Neurol ; 58(2): 153-64, 1999 Feb.
Article in English | MEDLINE | ID: mdl-10029098

ABSTRACT

We used a new approach, termed dynamic cortical deformation (DCD), to study the neuronal, vascular, and glial responses that occur in focal cerebral contusions. DCD produces experimental contusion by rapidly deforming the cerebral cortex with a transient, nonablative vacuum pulse of short duration (25 milliseconds) to mimic the circumstances of traumatic injury. A neuropathological evaluation was performed on brain tissue from adult rats sacrificed 3 days following induction of either moderate (4 psi, n = 6) or high (8 psi, n = 6) severity DCD. In all animals, DCD produced focal hemorrhagic lesions at the vacuum site without overt damage to other regions. Examination of histological sections showed localized gross tissue and neuronal loss in the cortex at the injury site, with the volume of cell loss dependent upon the mechanical loading (p < 0.001). Axonal pathology shown with neurofilament immunostaining (SMI-31 and SMI-32) was observed in the subcortical white matter inferior to the injury site and in the ipsilateral internal capsule. No axonal injury was observed in the contralateral hemisphere or in any remote regions. Glial fibrillary acidic protein (GFAP) immunostaining revealed widespread reactive astrocytosis surrounding the necrotic region in the ipsilateral cortex. This analysis confirms that rapid mechanical deformation of the cortex induces focal contusions in the absence of primary damage to remote areas 3 days following injury. Although it is suggested that massive release of neurotoxic substances from a contusion may cause damage throughout the brain, these data emphasize the importance of combined injury mechanisms, e.g. mechanical distortion and excitatory amino acid mediated damage, that underlie the complex pathology patterns observed in traumatic brain injury.


Subject(s)
Brain Chemistry/physiology , Brain Concussion/pathology , Brain Concussion/physiopathology , Cerebral Cortex/pathology , Animals , Astrocytes/chemistry , Biomechanical Phenomena , Cerebral Cortex/cytology , Cerebral Hemorrhage/pathology , Cerebral Hemorrhage/physiopathology , Disease Models, Animal , Glial Fibrillary Acidic Protein/analysis , Male , Necrosis , Neurofilament Proteins/analysis , Neurons/chemistry , Rats , Rats, Sprague-Dawley
17.
Biochem Cell Biol ; 76(2-3): 171-6, 1998.
Article in English | MEDLINE | ID: mdl-9923686

ABSTRACT

NMR is a vital tool for measuring the dynamics of biological macromolecules in solution. The chemical exchange observed is often divided into slow or intermediate exchange. Slow exchange affects principally the z magnetizations of the system and is observed in modified spin-lattice relaxation experiments. Intermediate exchange gives rise to broadening and coalescence in the spectrum itself. This broadened spectrum is often considered as a whole, but we have shown that it is better to regard it as a sum of transitions, with a generalized picture of the transition probability. In this paper, we give explicit expressions for the lineshape for two sites and review some of the recent applications of chemical exchange in biochemical NMR.


Subject(s)
Magnetic Resonance Spectroscopy/methods , Models, Chemical , Macromolecular Substances , Solutions , Time Factors
18.
J Surg Res ; 69(2): 344-8, 1997 May.
Article in English | MEDLINE | ID: mdl-9224404

ABSTRACT

The short-chain fatty acid butyrate (NaBu) selectively increases colonic crypt base proliferation and inhibits "premalignant" crypt surface hyperproliferation while the secondary bile acid deoxycholate (DCA) induces surface hyperproliferation, in vitro. We hypothesized that NaBu and DCA have similar selective and antagonistic effects on the colonic crypt proliferative pattern, in vivo. Fifty-six adult SD rats underwent surgical isolation of the colon and 24-hr intraluminal instillation with physiological (10 mM) and pharmacological (25 mM) levels of butyrate alone or combined with a physiological DCA level (5 microM). Bromodeoxyuridine-labeling indices (LI) were determined as labeled cells divided by total cells, for the whole crypt and five crypt compartments from base to surface. Treatment with NaBu increased total LI when compared to NaCl. This effect was significant only at the crypt base. Both doses of NaBu resulted in similar LI with no further response at the higher concentration. In contrast to prior in vitro studies, DCA alone at this concentration did not affect LI, but when combined with NaBu, DCA inhibited the effects of NaBu at the crypt base and surface. The conclusions are: (1) the in vivo proliferative effects of NaBu are selective to the crypt base, (2) an in vivo low physiological DCA level does not promote crypt surface hyperproliferation but does inhibit butyrate's proliferative effect, and (3) NaBu and DCA interact in a complex and antagonistic manner to selectively modulate crypt base and surface proliferation, in the rat colon, in vivo. These findings may have clinical relevance since colonic levels of NaBu and DCA are affected by diet.


Subject(s)
Butyrates/antagonists & inhibitors , Cell Division/drug effects , Colon/cytology , Deoxycholic Acid/pharmacology , Intestinal Mucosa/cytology , Animals , Bromodeoxyuridine , Colon/anatomy & histology , Intestinal Mucosa/drug effects , Male , Rats , Rats, Sprague-Dawley
19.
J Surg Res ; 73(1): 90-4, 1997 Nov.
Article in English | MEDLINE | ID: mdl-9441799

ABSTRACT

BACKGROUND: Improved organ preservation is essential for the success of small bowel transplantation. Small bowel is usually preserved in UW (University of Wisconsin) solution which does not contain glutamine (Gln), the principal fuel for the enterocyte. We hypothesized that Gln-supplemented UW would improve mucosal function and structure of cold preserved small intestine. MATERIALS AND METHODS: Jejunum (40 cm) was harvested from Lewis rats and preserved for 18 hr at 4 degrees C in saline; UW solution only; UW with 1, 2, or 4% Gln; and UW containing 1, 2, or 4% isonitrogenous balanced nonessential amino acids (NEAA). 14C glucose transport, mucosal protein, mucosal maltase and alkaline phosphatase, jejunal villous height, and histologic damage were measured. RESULTS: UW with 2% Gln significantly increased glucose transport and mucosal protein when compared to the 2% NEAA and UW-only groups. Two percent Gln significantly decreased histologic damage of jejunum following cold preservation. Increasing Gln to 4% did not significantly increase its efficacy when compared to the UW with 2% Gln group. There were no significant differences in the activities of mucosal maltase and alkaline phosphatase among the various treatment groups. CONCLUSIONS: The addition of Gln, optimally provided at a concentration of 2%, to UW solution may protect the preserved small bowel segments from cold ischemic injury and improve mucosal function.


Subject(s)
Glutamine/pharmacology , Intestine, Small/physiology , Intestine, Small/transplantation , Organ Preservation , Alkaline Phosphatase/metabolism , Animals , Biological Transport , Cold Temperature , Glucose/metabolism , Intestinal Mucosa/anatomy & histology , Intestinal Mucosa/physiology , Intestine, Small/anatomy & histology , Jejunum/anatomy & histology , Jejunum/physiology , Male , Organ Size , Proteins/metabolism , Rats , Rats, Inbred Lew , alpha-Glucosidases/metabolism
20.
Am J Physiol ; 269(6 Pt 1): G974-80, 1995 Dec.
Article in English | MEDLINE | ID: mdl-8572229

ABSTRACT

The effects of exogenous insulin-like growth factor-I (IGF-I) on colonic adaptation were examined in male Sprague-Dawley rats (n = 60, 225-275 mg) after either a 60% small bowel and cecal resection (RX) or mid-small bowel transection with reanastomosis (TX). Animals received a 7-day treatment with either IGF-I (2.4 mg.kg-1.day-1) or vehicle (V; 0.1 mol/l acetic acid). Body weight decreased significantly after resection (-25.6 +/- 4.0 g; P < 0.05 vs. TX/V). IGF-I treatment significantly reduced weight loss after resection (-12.4 +/- 3.8 g; P < 0.01 vs. RX/V) and induced significant weight gain after transection (15.6 +/- 4.0 g; P < 0.05 vs. TX/V). Plasma IGF-I decreased with resection (526 +/- 41 TX/V vs. 344 +/- 17 ng/ml RX/V; P < 0.01). IGF-I treatment significantly increased plasma IGF-I levels (805 +/- 100 ng/ml TX/IGF, 677 +/- 56 ng/ml RX/IGF). After resection, IGF-I treatment significantly increased colonic mucosal weight, DNA, protein content, and crypt depth when compared with resection alone (P < 0.05). Colonic water absorption, measured by an in vivo [3H]polyethylene glycol assay, was significantly increased by IGF-I treatment in resected animals (399 +/- 23 RX/IGF vs. 306 +/- 32 microliter.cm-1.h-1 RX/V; P < 0.05). Resection resulted in increased steady-state colonic IGF-I mRNA (182% of TX/V; P < 0.01) without significantly affecting IGF-I receptor mRNA expression. Regulation of IGF binding protein (BP)-3 and -4 was discoordinate, with IGFBP-3 mRNA tending to decrease with resection (67% of TX/V; P is not significant) and IGFBP-4 increasing significantly (191% of TX/V; P < 0.05). An important role for IGF-I in colonic adaptation after massive intestinal resection is indicated by 1) significantly enhanced colonic mucosal growth and water absorption with IGF-I treatment and 2) postresection upregulation of colonic IGF-I mRNA and alteration of IGFBP-3 and IGFBP-4 mRNA expression.


Subject(s)
Adaptation, Physiological , Colon/physiopathology , Insulin-Like Growth Factor I/genetics , Insulin-Like Growth Factor I/physiology , RNA, Messenger/metabolism , Short Bowel Syndrome/physiopathology , Animals , Intestinal Absorption , Intestinal Mucosa/physiopathology , Male , Rats , Rats, Sprague-Dawley
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