Biomedical subjects

J P Hart

Publications and source records attributed to J P Hart.

At least 19 recordsLinked to original sources

PubMed2005

Development of a screen-printed carbon electrochemical immunosensor for picomolar concentrations of estradiol in human serum extracts.

Investigations into the development of a prototype electrochemical immunosensor for estradiol (E(2)) are described. After optimising reagent loadings in a 96-well enzyme-linked immunosorbent assay (ELISA), antibodies (rabbit anti-mouse IgG and monoclonal mouse anti-E(2)) were immobilised by passive adsorption onto the surface of screen-printed carbon electrodes (SPCEs). A competitive immunoassay was then performed using an alkaline-phosphatase (ALP)-labelled E(2) conjugate. Calibration plots for E(2) buffer standards, performed colorimetrically on the SPCEs using a para-nitrophenyl phosphate substrate solution, were in good agreement with ELISA calibration plots. Electrochemical measurements were then performed using differential pulse voltammetry (DPV) following the production of 1-naphthol from 1-naphthyl phosphate. The calibration plot of DPV peak current versus E(2) concentration showed a measurable range of 25-500 pg/ml with a detection limit of 50 pg/ml. A coefficient of variation of between 13.0 and 15.6% was obtained for repeat measurements. The immunosensor was applied to the determination of E(2) in spiked serum, following an extraction step with diethyl ether. A mean recovery for the method of 102.5% was obtained with a CV of 19.1%. The options available for further development of the sensor regarding precision, limit of detection and direct sample analysis are discussed.

Antibodies, Monoclonal↗

PubMed2003

Development of an electrochemical assay for 2,6-dinitrotoluene, based on a screen-printed carbon electrode, and its potential application in bioanalysis, occupational and public health.

Screen-printed carbon electrodes (SPCEs) have been successfully exploited as disposable sensors for the measurement of 2,6-dinitrotoluene (2,6-DNT) using a stripping voltammetric method. Initial investigations were undertaken using cyclic voltammetry (CV) to characterise the redox behaviour at the SPCEs. Further studies were then performed to deduce the optimum applied potential and accumulation time for the stripping voltammetric procedure. In addition, a study was carried out to ascertain whether small volumes of samples could be reliably used for analysis. From these studies it was shown that a 100 microl aliquot of sample could be analysed and the calibration plot was linear from 161 ng ml(-1) to 137 microg ml(-1) (R(2)=0.9991), the former concentration being the detection limit. The effects of the major components of human saliva at concentrations normally present were investigated. Of the individual components tested, only Cl(-) and albumen were found to interfere. The presence of the latter could be easily overcome by the addition of (NH(4))(2)SO(4). An interference study was also carried out on some inorganic and organic species that may be present in water samples. The sensors were evaluated by carrying out 2,6-DNT determinations on spiked and unspiked human saliva, dust wipe and potable water samples. Mean recoveries of 47.5, 73.4 and 102.4% were obtained; coefficients of variation of 7.88, 6.63 and 6.42% were calculated for a concentration of 9.1 microg ml(-1) in water, 10.6 microg ml(-1) saliva samples, and 141.1 ng cm(-2) for dust wipe samples, respectively. The performance characteristics show that the method holds promise and reliable data may be obtained for 2,6-DNT in bioanalysis and public health.

Carbon↗

PubMed2003

Endovascular exclusion of iliac artery to iliac vein fistula after lumbar disk surgery.

Iliac arteriovenous (AV) fistula is rare after lumbar disk surgery. Traditionally, open repair through the arterial lumen was performed. We report endovascular exclusion of an iliac AV fistula in a 41-year-old woman 8 years after lumbar diskectomy. An angiogram showed an AV fistula connecting the right common iliac artery and vein. This was repaired with placement of two covered wall stents in the right common artery and external iliac artery, and embolization of the right internal iliac artery. Contrast medium-enhanced computed tomography scan at 5 months confirmed elimination of the AV fistula and right iliac artery patency. This technique should be considered in management of iliac AV fistulas.

Adult↗

PubMed2002

Development of disposable amperometric sulfur dioxide biosensors based on screen printed electrodes.

The possibility of developing amperometric biosensors for the measurement of SO(2) in flowing gas streams has been examined. Screen-printed carbon electrodes (SPCEs) were tailored with the enzyme sulfite oxidase and cytochrome c and the response is generated through the resulting enzymatic and electrocatalytic reactions involving SO(3)(2-), formed when SO(2) gas is dissolved in the supporting electrolyte. Two methods of integrating the enzyme and cytochrome c with the SPCE were investigated. In one design (b-type biosensor), the components were mixed thoroughly with the same ink used to produce the SPCEs, then the modified ink was spread over the working electrode. In the second approach the bio-components were dissolved in the supporting electrolyte and simply deposited on top of the transducer (s-type biosensor). Both devices gave linear responses over the range 4--50 ppm but the sensitivity of the s-type was approximately twice that of the b-type biosensor. In addition, the time taken to reach 90% of the maximum response (t(90%)) was 110 s for the s-type biosensor compared with 200 s for the b-type biosensor. These studies illustrate the successful use of biosensors for the detection of sulfur dioxide at the relatively low potential of +0.3 V versus Ag.AgCl and should provide useful alternatives for decentralised environmental studies.

Biosensing Techniques↗

PubMed2001

Kinetics of nonproteolytic incorporation of a protein ligand into thermally activated alpha 2-macroglobulin: evidence for a novel nascent state.

We have previously shown that antigens complexed to the receptor-recognized form of alpha(2)-macroglobulin (alpha(2)M*) demonstrate enhanced immune responsiveness mediated by the low density lipoprotein receptor-related protein LRP/CD91. Recently, we developed a proteinase-independent method to covalently bind antigens to alpha(2)M*. Given the potential applications of this chemistry, we analyzed the kinetics, thermodynamics, and pH dependence of this reaction. The incorporation of lysozyme into alpha(2)M* was a mixed bimolecular second-order reaction with a specific rate constant of 91.0 +/- 6.9 m(-1) s(-1), 50.0 degrees C, pH 7.4. The activation energy, activation entropy, and Gibbs' free energy at 50.0 degrees C were 156 kJ mol(-1), 266 J mol(-1) K(-1), and 70 kJ mol(-1), respectively. The rate of incorporation increased as a function of pH from pH 5.0 to 7.0 and was unchanged thereafter. Furthermore, the reaction between alpha(2)M* and lysozyme was irreversible. The data are consistent with a two-step mechanism. In the first step, alpha(2)M* reforms its thiol ester bond, entering a reactive state that mimics the proteolytically induced "nascent state." In the rate-limiting second step, the reformed bond quickly undergoes nucleophilic attack by lysozyme. The kinetic equations derived in this study are the basis for optimizing the formation of stable alpha(2)M*.antigen complexes.

Humans↗

PubMed2001

The non-specific inhibition of enzymes by environmental pollutants: a study of a model system towards the development of electrochemical biosensor arrays.

Previous research has shown that lactate dehydrogenase (LDH) was competitively inhibited by pentachlorophenol (PCP) and a modified assay produced a detection limit of 1 microM (270 microg l(-1)). This work used spectrophotometric rate-determination but in order to move towards biosensor development the selected detection method was electrochemical. The linkage of LDH to lactate oxidase (LOD) provided the electroactive species, hydrogen peroxide. This could be monitored using a screen-printed carbon electrode (SPCE) incorporating the mediator, cobalt phthalocyanine, at a potential of +300 mV (vs. Ag/AgCl). A linked LDH/LOD system was optimised with respect to inhibition by PCP. It was found that the SPCE support material, PVC, acted to reduce inhibition, possibly by combining with PCP. A cellulose acetate membrane removed this effect. Inhibition of the system was greatest at enzyme activities of 5 U ml(-1) LDH and 0.8 U ml(-1) LOD in reactions containing 246 microM pyruvate and 7.5 microM NADPH. PCP detection limits were an EC(10) of 800 nM (213 microg l(-1)) and a minimum inhibition detectable (MID) limit of 650 nM (173 microg l(-1)). The inclusion of a third enzyme, glucose dehydrogenase (GDH), provided cofactor recycling to enable low concentrations of NADPH to be incorporated within the assay. NADPH was reduced from 7.5 to 2 microM. PCP detection limits were obtained for an assay containing 5 U ml(-1) LDH, 0.8 U ml(-1) LOD and 0.1 U ml(-1) GDH with 246 microM pyruvate, 400 mM glucose and 2 microM NADPH. The EC(10) limit was 150 nM (39.9 microg l(-1)) and the MID was 100 nM (26.6 microg l(-1)). The design of the inhibition assays discussed has significance as a model for other enzymes and moves forward the possibility of an electrochemical biosensor array for pollution monitoring.

Biosensing Techniques↗

PubMed2001

An electrochemical immunosensor for milk progesterone using a continuous flow system.

An electrochemical biosensor for cow's milk progesterone has been developed and used in a competitive immunoassay under thin-layer, continuous-flow conditions. Single-use biosensors were fabricated by depositing anti-progesterone monoclonal antibody (mAb) onto screen-printed carbon electrodes (SPCEs). Three operational steps could be identified: (1) Competitive binding of sample/conjugate (alkaline-phosphatase-labelled progesterone, AP-prog) mixture, (2) establishment of a steady-state amperometric baseline current and (3), measurement of an amperometric signal in the presence of enzyme substrate (1-naphthyl phosphate, 1-NP). In the thin-layer cell, the enzyme product, 1-naphthol, showed electrochemical behaviour consistent with bulk conditions and gave a linear amperometric response under continuous-flow conditions (E(app)=+0.3 V vs. Ag/AgCl) over the range 0.1-1.0 microg/ml. After pre-incubating biosensors with progesterone standards, signal generation within the cell (substrate concentration=5 mM) was recorded amperometrically as rate (nA/s) or maximum current (i(max), nA). Response values for milk standards were approximately 50% of those prepared in buffer. In both cases, calibration plots over the range 0-50 ng/ml progesterone were obtained. By conducting sample binding under flowing conditions, only 7% of the previous response was obtained, even at a substrate concentration of 50 mM, resulting in low signal:noise ratio. Using a stop-flow arrangement (i.e. quiescent sample binding, followed by continuous flow), low-noise amperograms were obtained at [1-NP]=5 mM. Calibration plots were obtained over the range 0-25 ng/ml, with a coefficient of variation of 12.5% for five replicate real milk samples.

Animals↗

PubMed2001

An assay for the enzyme N-acetyl-beta-D-glucosaminidase (NAGase) based on electrochemical detection using screen-printed carbon electrodes (SPCEs).

An electrochemical assay for the enzyme N-acetyl-beta-D-glucosaminidase (NAGase) is described, using bare screen-printed carbon electrodes (SPCEs). The enzyme substrate, 1-naphthyl-N-acetyl-beta-D-glucosaminide, was added to the NAGase-containing sample under hydrodynamic conditions and was hydrolysed to 1-naphthol, which was monitored amperometrically at an Eapp of +650 mV versus SCE. A pH study revealed the apparent Vmax for the assay to occur at pH 4.5. corresponding to an apparent substrate Km of 0.28 mM. In order to be compatible with the analysis of biological fluids, a final operating pH of 5.4 was selected, and, using a data recording time of 100 s post-substrate addition, the assay gave a linear response (r2 = 0.988) over the range 3.1 to 108 mU ml(-1) NAGase (RSD = 15.4%). This assay has the potential to monitor NAGase levels in a number of application areas.

Acetylglucosaminidase↗

PubMed2001

Uncertainty estimation on the quantification of major milk proteins by liquid chromatography.

A detailed uncertainty budget is evaluated for the quantification of major milk proteins separated by reversed phase ion-pair high performance liquid chromatography (RP-IP HPLC). Recommendations from the International Organisation for Standardisation, Guide to the Expression of Uncertainty and the EURACHEM/CITAC Guide "Quantifying Uncertainty in Analytical Measurement" were followed resulting in the expression of combined uncertainties as an expanded uncertainty. The authors have identified the lack of a detailed description on all possible sources of uncertainty on chromatographic milk protein separations. Up to now, uncertainty has only been expressed as a random chromatographic variability, being exclusively measured by regression equations. On the contrary, the establishment of a full uncertainty budget permits a complete identification of all sources of uncertainty associated with the measurement. Thus, a better comprehension of the method is obtained. Having identified all sources of uncertainty, to the best of our knowledge, they are minimised (whenever possible) and combined. The importance of this identification is crucial, in particular, concerning previously neglected sources, in this example the combination of the interpolated injected mass of protein and its purity, having a dominant influence on the total combined uncertainty. The quality of the measurement (measured by its associated uncertainty statement, which should be based on a full uncertainty budget evaluation) is demonstrated. Moreover, due to the high precision of the proposed method, the total protein content, in addition to the group protein composition (i.e. total casein and whey protein content) is calculated with high reliability, which is an extremely useful factor regarding the establishment of milk provenance/adulteration. Combined relative standard uncertainties ranging from 3.3 up to 12.5% for individual protein concentration were found, whereas for total protein content, an overall combined relative standard uncertainty of 2.7% (liquid) and 3.3% (powdered samples) was achieved.

Animals↗

PubMed2001

Towards the development of molecularly imprinted polymer based screen-printed sensors for metabolites of PAHs.

This paper describes the fabrication of a sensor for 1-hydroxypyrene (1-OHP) based on a screen-printed carbon electrode (SPCE) modified with a molecularly imprinted polymer (MIP); 1-OHP was chosen as a model metabolite of polyaromatic hydrocarbons (PAHs). It was shown that 1-OHP could be readily oxidised at a plain SPCE and the electrochemical mechanism was found to involve an ECE (electron transfer-chemical reaction-electron transfer) process. The MIP for 1-OHP was prepared using only divinylbenzene (DVB) and styrene as monomers and the binding was only based on hydrophobic interactions. Batch binding studies revealed that optimum uptake of 1-OHP by the MIP occurred from solutions containing 35% water in methanol. Selectivity of the binding sites in the MIP was examined by performing uptake studies in the same solution containing either phenol or 1-naphthol; the specific binding of 1-OHP was twenty times greater than the former and five times greater than the latter. Preliminary calibration studies were performed with the MIP-SPCE using a two-step approach; accumulation was carried out in 35% water in methanol followed by measurement in 50% methanol-0.025 mol dm(-3) phosphate buffer pH 12. This two-step non-competitive affinity assay gave encouraging results and indicated potential for use in pollution studies.

Journal Article↗

PubMed2000

Development of a disposable ethanol biosensor based on a chemically modified screen-printed electrode coated with alcohol oxidase for the analysis of beer.

A disposable amperometric biosensor for the measurement of ethanol has been developed. It comprises a screen-printed carbon electrode doped with 5% cobalt phthalocyanine (CoPC-SPCE), and coated with alcohol oxidase; a permselective membrane on the surface acts as a barrier to interferents. The measurement of ethanol is based on the signal produced by H2O2, the product of the enzymatic reaction. Optimisation studies were performed using amperometry in stirred solution and the magnitude of the signal was found to be dependent on pH, enzyme loading, type of membrane and applied potential. The same technique was used to evaluate the biosensor for the determination of ethanol in samples. The results obtained compared well with the manufacturers specifications. In order to test the possibility of using the devices in the field, chronoamperometry was also used to determine ethanol in the same beer samples. The precision and recovery data again indicated that the biosensor should give reliable results under the conditions described.

Alcohol Oxidoreductases↗

PubMed2000

Improvement of rejection-induced diastolic abnormalities in rat cardiac allografts with inducible nitric oxide synthase inhibition.

OBJECTIVE: Inhibition of inducible nitric oxide synthase (nitric oxide II) activity has been proposed as a method to attenuate capillary leak and edema during rejection of heterotopically transplanted rat hearts. Myocardial edema has previously been implicated in diastolic dysfunction during allograft rejection. Accordingly, we tested the hypothesis that inducible nitric oxide synthase inhibition with aminoguanidine would alleviate left ventricular stiffening and myocardial edema formation in 4-day heterotopic rat heart allografts. METHODS: Passive left ventricular filling was studied in American Cancer Institute Lewis rats receiving heterotopic heart transplants receiving either aminoguanidine, a selective nitric oxide synthase inhibitor (n = 6); dexamethasone (1 mg. kg(-1). d(-1) administered subcutaneously) for 4 days after transplantation (n = 6); or intravenous saline solution (n = 6). American Cancer Institute-to-American Cancer Institute isografts (n = 6) were used as controls. RESULTS: Serum nitrite/nitrate levels in the aminoguanidine group (18 +/- 3 mmol/L) and dexamethasone group (22 +/- 4 mmol/L) were reduced versus the intravenous saline group (144 +/- 36 mmol/L [SEM]) to levels seen in controls (25 +/- 9 mmol/L). Left ventricular volume at 15 mm Hg for the aminoguanidine group was increased versus that for the intravenous saline solution group, similar to that for controls, and reduced versus dexamethasone-treated animals. Myocardial water content for the aminoguanidine-treated animals (78.3% +/- 0.4%) was similar to those of intravenous saline-treated animals (78.0% +/- 0. 3%) but greater than those of controls (77.1% +/- 0.2%) and dexamethasone-treated animals (76.7% +/- 0.3%). CONCLUSIONS: Nitric oxide II inhibition with aminoguanidine minimizes the reduction in left ventricular filling that is seen with allograft rejection through a mechanism that is not associated with attenuation of myocardial edema.

Animals↗

PubMed1999

A comparison of 1-naphthyl phosphate and 4 aminophenyl phosphate as enzyme substrates for use with a screen-printed amperometric immunosensor for progesterone in cows' milk.

4-Aminophenyl phosphate (4-APP) and 1-naphthyl phosphate (1-NP) were compared as enzyme substrates for an amperometric milk progesterone biosensor utilising progesterone-conjugated alkaline phosphatase in a competitive immunoassay format. Cyclic voltammetry of the corresponding hydrolysis products, 4-aminophenol and 1-naphthol, at the surface of screen-printed carbon base transducers, uncoated or coated with anti-progesterone monoclonal antibody (mAb) showed well-defined anodic responses for both species, with the more sensitive being 4-aminophenol. Scan rate studies produced evidence that surface mAb could impede the diffusion of 4-aminophenol, but not 1-naphthol, toward the electrode surface. This was supported by computer simulation for the electrochemical rate constant (khet) using 4-aminophenol, which gave values at uncoated and mAb-coated electrodes of 6.5 x 10(-4) and 3.0 x 10(-4) cm s-1, respectively. The applied potential for oxidation of 4-aminophenol was 230 mV lower than for 1-naphthol. Nevertheless, by operating below +400 mV versus a saturated calomel reference electrode, it was possible to obtain a chronoamperometric signal for 1-naphthol in the absence of electrochemical interference from milk. Using mAb-coated SPCEs, calibration curves were obtained for progesterone in oestrus whole cow's milk spiked with standard concentrations over the range 0-50 ng/ml, using either 4-APP or 1NP as enzyme substrate. Precision values for triplicate sensors were 5.3-18.3% for 4-APP and 4.1-12.4% for 1-NP. An assay of real whole milk samples from different cows at various stages of the oestrus cycle produced correlations against a commercial EIA of r = 0.840 and 0.946 for 4-APP and 1-NP, respectively, 1-NP possesses the advantages over 4-APP of being inexpensive, easy to obtain and soluble (1-naphthol cf. 4-aminophenol) at high pH. From these observations, it is concluded that 1-NP is the preferred substrate for use with our proposed milk progesterone biosensor.

Alkaline Phosphatase↗

PubMed1999

Pressure volume curves in arrested heterotopic rat heart isografts: role of improved myocardial protection.

BACKGROUND: To minimize decreases in left ventricular (LV) compliance immediately after rat heart transplantation, we tested several different methods of myocardial protection. MATERIALS AND METHODS: Five groups of ACI rat hearts (n = 6 each) were arrested by coronary perfusion with 5 ml of UW (University of Wisconsin), UW-BDM (UW with 2,3-butanedione monoxime), CU (Columbia University), or CU-BDM solution or by LV injection of potassium chloride and Ringer's lactate immersion (KCl/RL). After abdominal isografting and blood reperfusion for 15 min, transplanted hearts (TxH) were arrested and excised. Diastolic LV pressure-volume curves (LVPVCs) were correlated with myocardial water content (MWC). Native hearts (NH) were arrested identically to TxH and maintained at 4 degrees C by immersion. LVPVCs were measured at 15-min intervals for 90 min. RESULTS: In three of four pressure intervals at Time 0, normalized LV volume (LVV) was smaller (P < 0.05, ANOVA) in KCl/RL native hearts than in the four perfusion groups. LVV decreased significantly in NH after 45-75 min; LVV decreased similarly with time in all groups. In TxH, postarrest LVVs were higher with UW-BDM, CU-BDM, and CU than with UW or KCl/RL (P < 0.05, ANOVA). Expressing LVV of TxH as a percentage of NH, UW-BDM, CU, and CU-BDM provided qualitatively better diastolic properties than KCl/RL and UW. CONCLUSIONS: Thus rat LVPVCs can be improved after heart transplantation with alternative strategies of myocardial protection. KCl arrest decreases LV filling volume in this model and should be avoided.

Abdomen↗

PubMed1999

Coronary perfusate composition influences diastolic properties, myocardial water content, and histologic characteristics of the rat left ventricle.

BACKGROUND: Recent studies found that edema, histology, and left ventricular diastolic compliance exhibit quantitative relationships in rats. Edema due to low osmolarity coronary perfusates increases myocardial water content and histologic edema score and decreases left ventricular filling. The present study examined effects of perfusate osmolarity and chemical composition on rat hearts. METHODS: Arrested American Cancer Institute (ACI) rat hearts (4 degrees C) were perfused with different cardioplegia solutions, including Plegisol (289 mOsm/L), dilute Plegisol (172 mOsm/L), Stanford solution (409 mOsm/L), and University of Wisconsin solution (315 mOsm/L). Controls had blood perfusion (310 mOsm/L). Postmortem left ventricular pressure-volume curves and myocardial water content were measured. After glutaraldehyde or formalin fixation, dehydration, and paraffin embedding, edema was graded subjectively. RESULTS: Myocardial water content reflected perfusate osmolarity, being lowest in Stanford and University of Wisconsin solutions (p<0.05 versus other groups) and highest in dilute Plegisol (p<0.05). Left ventricular filling volumes were smallest in dilute Plegisol and Plegisol (p<0.05). Osmolarity was not a major determinant of myocardial edema grade, which was highest with University of Wisconsin solution and dilute Plegisol (p<0.05 versus other groups). CONCLUSIONS: Perfusate osmolarity determined myocardial water content and left ventricular filling volume. However, perfusate chemical composition influenced the histologic appearance of edema. Pathologic grading of edema can be influenced by factors other than osmolarity alone.

Adenosine↗

PubMed1999

The changing landscape of health care financing and delivery: how are rural communities and providers responding?

Rural communities have not kept pace with the recent dramatic changes in health care financing and organization. However, the Medicare provisions in the Balanced Budget Act of 1997 will require rural providers to participate in the new systems. Case studies revealed the degree of readiness for change in six rural communities and charted their progress along a continuum, as reflected in three sets of activities: the development of networking; the creation of new strategies for managing patient care; and the adoption of new methods for contracting with health insurers. Some communities had constructed highly integrated systems, whereas others were just beginning to change their billing practices; a few were signing contracts for capitated care, in contrast to those that were resisting discounts in current fee structures. These six rural areas still have considerable ground to cover before their health care organization and financing reach the levels achieved by urban communities.

Aged↗

PubMed1998

A novel arresting solution for study of postmortem pressure--volume curves of the rat left ventricle.

OBJECTIVE: We have found diastolic properties of the rat heart extremely sensitive to the method used to induce arrest. Accordingly, we sought to develop a reliable solution for measuring the LV pressure-volume relationship (LVPVR) in the rat. MATERIALS AND METHODS: The study had five phases: (i) K120Na100, consisting of KCl (120 mEq/L) in NaCl (100 mEq/L) diluted with distilled water was developed in preliminary experiments. (ii) ACI rats were arrested with 3 cc of 4 degreesC KCl (n = 6) or K120Na100 (n = 6) infused into the aortic root. The LVPVR was expressed as normalized volume (Vn) at standardized pressures. Myocardial water content (%MWC) was determined. (iii) Six hearts were arrested with K120Na100 and LVPVRs observed over 1 h. (iv) Four hearts were instrumented with sonomicrometry crystals to compare in vivo and postmortem pressure diameter data. (v) The relation between body weight and dry heart weight was determined in 48 animals. RESULTS: In hearts arrested with KCl, mean Vn at pressures of 10, 15, and 20 mmHg (206 +/- 26, 306 +/- 21, and 336 +/- 25 microl, respectively) was significantly reduced vs K120Na100 hearts (345 +/- 11, 407 +/- 12, and 472 +/- 18 microl) (P < 0.05). Mean %MWC changed insignificantly. Vn at 20 mm Hg became significantly smaller vs initial data 60 min after arrest with K120Na100 (P < 0.05, ANOVA). No differences between in vivo and postmortem mean normalized diameter were observed. The correlation coefficient for the relation between body weight and dry heart weight was 0.80. Conclusions. K120Na100 at 4 degreesC reliably preserves LV diastolic properties in the rat heart for 30 min. Normalization of LV volume to body weight is justified.

Animals↗

PubMed1998

Intraoperative echocardiography: interpretation of changes in left ventricular wall thickness.

Quantitative two-dimensional echocardiography (Q2-DE) may be used to detect intraoperative changes in left ventricular (LV) mass (M) and wall thickness (h). Potential causes of change in h include physiological redistribution of myocardium, myocardial edema, reactive hyperemia, and intramyocardial hemorrhage. Changes in h, in the absence of changes in LV shape and volume, generally indicate increased LVM. When changes in h are accompanied by changes in shape or volume, changes in LVM can only be detected by mathematical modeling, unless the direction of the observed changes is opposite that expected with physiological redistribution. Histological observations essential to understanding current mathematical models are presented and related to the inherent solid geometry. Technical considerations in determination of LV mass by Q2-DE are discussed. New procedures that alter LV volume and geometry, such as the Batista operation, defy modeling by conventional methods. Modeling techniques that allow an experimental approach to understanding LVM and h under such conditions are presented.

Cardiomyopathies↗