What is optimal flow using a mini-bypass system?

The purpose of this study is to determine the appropriate arterial pump flow /cardiac index (CI) utilizing a mini-bypass system. The unique feature of most mini-bypass systems is that the centrifugal pump combines the function of kinetic venous drainage with arterial pump flow. Therefore, if drainage is reduced, arterial pump flow is also reduced. Managing this system can present challenges to the clinical perfusionist. We reviewed fifteen cases, using the Medtronic Resting Heart System (RHS). This retrospective study examined the arterial pump flow, measured as cardiac index (CI), mean arterial pressure, inlet venous saturation, urine output, vasopressor use, and lactate production during routine cardiac surgery. The mean cardiac index for all patients was 1.90 +/- 0.14, range 1.63-2.08 L/min/m(2). The mean hemoglobin on cardiopulmonary bypass (CPB) was 10.6 +/- 1.2, with a range of 9.2-13.3 g/dL. The lactate produced on CPB was 2.03 +/-0.67 with a range of 1.5-3.5 mmol/L. The mean change in lactate measured from pre CPB to post CPB was 0.85 +/- 0.71 with a median lactate of 0.6 mmol/L. The venous saturation was 65.53 +/- 6.03% with a median of 65% and a range of 57-82%. The mean arterial pressure was 67.04 +/- 10.45 mmHg with a median of 62.5 mmHg. The median urine output was 125 mls. The vasopressor median was 2200 microg. All patients were maintained on CPB with a mean nasopharyngeal temperature of 35.43 degrees Celsius. Despite using lower than predicted flows, it would appear that adequate perfusion is provided. The higher hemoglobin content achieved through reduced hemodilution and reduced inflammation appears to enable this system to deliver adequate flow and perfusion at reduced cardiac indices. This research provides evidence which challenges longstanding beliefs that a cardiac index of 2.4 L/min/m(2) is required for all cases.

The use of a mini bypass circuit for minimally invasive mitral valve surgery

Introduction: The purpose of the study is to clinically evaluate minimally invasive mitral valve surgeries (MIMVS) using a mini bypass circuit. The challenge to perfusion is to keep pace with MIMVS, with demonstrated improvements in perfusion-related technologies.

Methods: From October 28, 2005 to September 10, 2008, we retrospectively evaluated thirty-four elective cases which used the mini-circuit (Medtronic Resting Heart System®), with respect to safety, efficacy, cannulation technique, blood usage, resultant hemoglobin, length of ICU and hospital stay, and complications.

Conclusion: The Medtronic Resting Heart System® alleviates many factors, such as high shear stress, turbulence, air to blood interface and decreased oncotic pressure caused by hemodilution, providing more efficient perfusion to our MIMVS patients. We demonstrate, with minor circuit modifications and attention to venous air issues, that this mini-circuit can be used safely and effectively, while being associated with improvements in patient outcomes.

A differential thermal expansion approach to crystal structure determination from powder diffraction data

Differential thermal expansion over the range 90–210 K has been applied successfully to determine the crystal structure of chlorothiazide from synchrotron powder diffraction data using direct methods. Key to the success of the approach is the use of a multi-data-set Pawley refinement to extract a set of reflection intensities that is more `single-crystal-like' than those extracted from a single data set. The improvement in reflection intensity estimates is quantified by comparison with reference single-crystal intensities.

Immobilization of mycobacterial cells onto silicone--assessing the feasibility of the immobilized biocatalyst in the production of androstenedione from sitosterol

Silicone rubbers are hydrophobic, a feature that may prove advantageous if this material is to be used as immobilization matrix in bioconversion systems where hydrophobic species are present, such as sterols and mycobacterial cells. Mycobacterium sp. cells with sitosterol side chain cleavage activity were accordingly effectively adsorbed onto silicone and the potential application of the concept was assessed by matching the behavior of the resulting immobilized biocatalyst with free cells and Celite immobilized cells. Mass transfer, kinetics, thermal and storage stability characterization of a biotransformation system based in the use of the silicone immobilized biocatalyst was performed. The feasibility of biocatalyst reutilization was tentatively explored.

Technical note: a comparison of central and peripheral intraocular pressure using rebound tonometry

PURPOSE

To compare central and peripheral intraocular pressure (IOP) readings obtained with rebound tonometry.

METHODS

Intraocular pressure was measured on the right eye of 153 patients (65 males, 88 females), aged from 21 to 85 years (mean +/- S.D., 55.5 +/- 15.2 years) with the ICare rebound tonometer at centre, and 2 mm from the limbus (in the nasal and temporal regions along the 0-180 degrees corneal meridian).

RESULTS

Intraocular pressure values obtained with the ICare were 14.9 +/- 2.8; 14.1 +/- 2.5 and 14.5 +/- 2.7 mmHg at centre, nasal and temporal corneal locations, respectively. On average, nasal and temporal IOP readings were 0.75 and 0.37 mmHg lower than the central reading (p < 0.05 and p > 0.05, respectively). A highly significant correlation was found between central and peripheral measurements in nasal (r(2) = 0.905; p < 0.001) and temporal (r(2) = 0.879; p < 0.001) regions along the horizontal meridian. Almost 80% of patients presented nasal IOP values within +/-1 mmHg of the central value.

CONCLUSIONS

Intraocular pressure values measured with the ICare rebound tonometer on the nasal corneal region is slightly lower on average and highly correlated with IOP values recorded at corneal centre. Both nasal and temporal readings are in good agreement with central IOP, and could be used to obtain a reliable estimate of rebound IOP in corneas where central readings cannot be taken.

Polarization studies of resonant forbidden reflections in liquid crystals

We report the results of resonant x-ray diffraction experiments performed on thick films of a biaxial liquid crystal made of achiral bent-core molecules. Polarization properties of forbidden reflections are observed as a function of the sample rotation angle phi about the scattering vector Q for the first time on a fluid material. The experimental data are successfully analyzed within a tensor structure factor model by taking the nonperfect alignment of the liquid crystal into account. The local structure of the B2 mesophase is hence determined to be SmC_{S}P_{A}.

Phytosterols: applications and recovery methods

Phytosterols, or plant sterols, are compounds that occur naturally and bear close structural resemblance to cholesterol, but have different side-chain configurations. Phytosterols are relevant in pharmaceuticals (production of therapeutic steroids), nutrition (anti-cholesterol additives in functional foods, anti-cancer properties), and cosmetics (creams, lipstick). Phytosterols can be obtained from vegetable oils or from industrial wastes, which gives an added value to the latter. Considerable efforts have been recently dedicated to the development of efficient processes for phytosterol isolation from natural sources. The present work aims to summarize information on the applications of phytosterols and to review recent approaches, mainly from the industry, for the large-scale recovery of phytosterols.

Unique pitch evolution in the smectic-C+alpha phase

Employing resonant x-ray diffraction, we observed unique pitch evolutions in the smectic-C*(alpha) phase in mixtures of two antiferroelectric liquid crystals. Our results show that the pitch in this phase continuously evolves across 4 layers, contradicting a theoretical model that predicts that the smectic-C*(FI2) phase intervenes in the smectic-C*(alpha) phase. The phase sequences we found can be explained by another model that includes one type of long-range interaction among smectic layers.

Technical Note: Accuracy and repeatability of a new portable ultrasound pachymeter

PURPOSE

To assess the accuracy and repeatability of central corneal thickness (CCT) measurements taken with a new portable ultrasound (US) pachymeter.

METHODS

Central thickness measurements were taken with a portable pachymeter (SP-100 Handy; Tomey, Nagoya, Japan) and a conventional US pachymeter (Nidek UP-1000; Nidek Technologies, Gamagori, Japan) from 57 right corneas of 57 young adults (19 males, 38 females) aged 18-44 years (mean +/- S.D., 22.95 +/- 3.92). Three repeated measures were obtained and then compared to obtain the repeatability of each instrument and the agreement between the pachymeters. The three readings taken with the portable pachymeter were compared against each other in order to evaluate intra-session repeatability and bias of each individual measurement with respect to the mean of three.

RESULTS

Mean values of CCT were 537 +/- 35 microm for conventional and 534 +/- 35 microm for the new portable pachymeter. A high agreement was found between the two instruments (mean difference = 2.58 microm; 95% CI 1.41-3.75 microm) with only two eyes presenting differences larger than +/-8.6 microm which represents 95% CI in the Bland-Altman plots which represents 1.6% of the mean CCT. The first reading taken showed the highest agreement with the mean value for the portable pachymeter.

CONCLUSIONS

The instrument tested in this study is able to take reliable measurements of corneal thickness even if a single reading is considered. Intra-session repeatability was very high, as was also the agreement between the average of three readings taken with the two US pachymeters.

Magnetic reconnection and plasma dynamics in two-beam laser-solid interactions

We present measurements of a magnetic reconnection in a plasma created by two laser beams (1 ns pulse duration, 1 x 10(15) W cm(-2)) focused in close proximity on a planar solid target. Simultaneous optical probing and proton grid deflectometry reveal two high velocity, collimated outflowing jets and 0.7-1.3 MG magnetic fields at the focal spot edges. Thomson scattering measurements from the reconnection layer are consistent with high electron temperatures in this region.

Applied microbiology and biotechnology in the conservation of stone cultural heritage materials

The contribution of applied microbiology and biotechnology for the preservation and restoration of culturally relevant stoneworks has been used only to a minor extent. Until recently it only involved the identification of the living organisms accountable for the deterioration of those materials by classic phenotypic identification methods. This seems to be changing, given the amount of work recently published that focuses in the introduction of molecular-based techniques for the detection of microorganisms in historic stone. Such techniques complement and expand the information up till now gathered by conventional identification methods. Along with this, efforts are being made to develop and implement bio-based methodologies that may actively contribute to the bioremediation of weathered historic stoneworks. The present mini-review aims to provide an overview of recent findings on these matters.

Noncompaction of ventricular myocardium

Noncompaction of ventricular myocardium is a rare cardiomyopathy thought to be caused by arrest of normal embryogenesis of the endocardium and myocardium; its true prevalence is still uncertain. A strong association between noncompaction and neuromuscular disorders has been described. Its major clinical manifestations are heart failure, arrhythmias and systemic embolic events. Diagnosis of noncompaction of ventricular myocardium can be made by conventional two-dimensional and color Doppler echocardiography. Recently contrast echocardiography has been used to provide a definitive diagnosis in most cases in which conventional echocardiography could not do so. We describe the case of a patient with clinical suspicion of noncompaction of ventricular myocardium established by conventional two-dimensional and color Doppler echocardiography and definitive diagnosis, as well as additional information, obtained by cardiac magnetic resonance imaging. We also discuss the difficulties in defining the therapeutic approach.

Age differences in central and peripheral intraocular pressure using a rebound tonometer

AIM

To evaluate the influence of age on the measurements and relationships among central and peripheral intraocular pressure (IOP) readings taken with a rebound tonometer.

METHODS

The IOPs were measured using the ICare rebound tonometer on the right eyes of 217 patients (88 men and 129 women) aged 18-85 years (mean 45.9 (SD 19.8) years), at the centre and at 2 mm from the nasal and temporal limbus along the horizontal meridian. Three age groups were established: young (< or =30 years old; n = 75), middle aged (31-60 years old; n = 77) and old patients (>60 years old; n = 65).

RESULTS

A high correlation was found between the central and peripheral IOP readings, with the central readings being higher than the peripheral ones. Higher IOP values for the central location were found in the younger patients. Older patients had significantly lower temporal IOP readings than those for the remaining two groups (p<0.001), whereas no significant differences were found among groups when IOP was measured at the central and nasal locations. A significant decrease was observed in the nasal and temporal IOP readings as the age increased (p = 0.011 and 0.006, respectively).

CONCLUSION

Older patients had lower IOP values than the middle-aged and younger patients in the temporal peripheral location. A negative correlation was found between age and IOP by rebound tonometry in the corneal periphery but not in its centre.