Rational approach to combined carotid and ischaemic heart disease

BACKGROUND

The management of patients with concomitant coronary and carotid artery disease remains a controversial subject. The aim of this review was to develop a rational plan for the management of such patients based on a review of the literature.

METHOD AND RESULTS

A retrospective review was carried out of relevant papers derived from the Medline database from 1964 to 1996.

CONCLUSION

The management of patients with concomitant coronary and carotid artery disease has not yet been put to the test in a properly designed and randomized multicentre trial. It is suggested that, until the results of such a trial are available, the rational approach to combined symptomatic disease is combined carotid endarterectomy and coronary artery bypass grafting (CABG). Combined surgery is also appropriate for patients with symptomatic carotid artery disease and significant but asymptomatic cardiac disease. At present there is inadequate evidence to promote carotid endarterectomy for asymptomatic disease in combination with CABG.

Optimizing a limiting dilution culture system for quantifying the frequency of interleukin-2-producing alloreactive T helper lymphocytes

BACKGROUND

The development of sensitive, specific, and reproducible techniques to quantify T cells with direct allospecificity has potential applications in the selection of bone marrow donors and in the monitoring of the antidonor alloresponse in patients after organ transplantation. Such data may provide an objective basis for altering existing immunosuppression, monitoring novel antirejection therapies, and predicting long-term graft outcome. We have previously published a correlation between donor antirecipient T helper frequencies (HTLf) and the severity of acute graft-versus-host disease after bone marrow transplantation. Using the same assay protocol, we have described the development of donor-specific hyporesponsiveness in a proportion of renal transplant recipients. However, several imperfections existed in the protocols used in these studies. Cellular interactions within the stimulator and the responder cell populations, and back stimulation of T cells within the stimulator cell population, could give rise to extraneous interleukin-2 and alter the validity or estimation of derived recipient antidonor HTLf.

METHODS

Using peripheral blood mononuclear cells as the responding population and splenic mononuclear cells as the stimulating population, we have examined the possible effects of these cellular interactions on the results of limiting dilution analysis assays for HTLf measurement.

RESULTS

These interactions have the ability to alter the validity or estimation of HTLf. We show that by depleting the responder population of HLA class II+ cells and depleting T cells from the stimulating population, these interactions are effectively abrogated.

CONCLUSIONS

On the basis of the findings reported here, we describe an optimized HTLf assay which is sensitive, specific, and reproducible. This has obvious applications in the analysis of alloimmune responses in transplantation.

Effect of cardiopulmonary bypass perfusion protocols on gut tissue oxygenation and blood flow

BACKGROUND

Previous studies in patients undergoing cardiopulmonary bypass (CPB) have documented gastric mucosal hypoperfusion and hypoxia. This study examines the influence of the CPB protocol on the adequacy of gut blood flow and oxygenation.

METHODS

Twenty-four patients were prospectively randomized into one of four CPB groups: nonpulsatile hypothermic (NP 28); pulsatile hypothermic (P 28); non-pulsatile normothermic (NP 37); and pulsatile normothermic (P 37). Gastric wall blood flow was assessed using laser Doppler flow measurement and gastric mucosal oxygenation (intramucosal pH), using tonometry.

RESULTS

After 10 minutes of CPB, the NP 28 group had the greatest reduction in gastric wall blood flow (-60.6% +/- 3.8%) compared with baseline (p < 0.05). Thirty minutes into CPB, the P 37 group had less gastric mucosal hypoperfusion (-9.7% +/- 10.3%) than the NP 28 patients (-53.0% +/- 8.6%; p < 0.05). All groups showed a hyperemic response immediately after CPB. No significant differences between the four groups were found for gastric mucosal oxygenation during or after CPB. A progressive decline occurred in this variable during the period 3 to 4 hours after CPB. At this time, total-body oxygen consumption and extraction were at their maximum.

CONCLUSIONS

This study found that perfusion protocol can influence mucosal blood flow, but other overriding factors that operate during and after CPB act to cause mucosal hypoxia. These findings, particularly the timing of mucosal hypoxia, may have implications for centers contemplating early extubation or "fast tracking" of patients after CPB.

Mutation of recombinant complement component C9 reveals the significance of the N-terminal region for polymerization

Complement component C9 binds to C5b-8 sites on target cells and polymerizes to form the membrane attack complex (MAC). The aim of the work reported here was to discover which region within C9 was responsible for protecting the globular protein against self-polymerization. Computer prediction modelling highlighted the domain at the N-terminus of C9, which was then investigated by site-directed mutagenesis. The mutated proteins were expressed using insect cells infected with baculovirus. Removal of 16, 20 or 23 amino acids at the N-terminus of C9 resulted in inactivation due to self-polymerization. In contrast, removal of 4, 8 or 12 amino acids resulted in a C9 that did not polymerize spontaneously, had two to threefold enhanced lytic activity on erythrocytes, and had increased binding to C5b-8 sites on rat neutrophils. These results suggest that the domain within the first 16 amino acids at the N-terminus of C9 is crucial in preventing the self-polymerization of the globular protein. We have also found that C9 contains a motif (27WSEWS31) common to a family of cytokine receptors that is similar to a tryptophan-rich motif (WEWWR) of the membrane pore formers, thiol-activated cytolysins. Mutation of this motif in C9 resulted in polymerized protein, consistent with this site keeping the N-terminus in a protected conformation and preventing premature self-polymerization.

Survival and cause of death after mitral valve replacement in patients aged 80 years and over: collective results from the UK heart valve registry

OBJECTIVE

Over the last decade there has been an increasing number of patients aged 80 years and over undergoing heart valve replacement. However, literature on the outcome of mitral valve replacement (MVR) in this age group is still limited.

METHODS

We conducted the present study by analysing data extracted from the UK Heart Valve Registry. From January 1986 to December 1994, 86 patients underwent isolated MVR and 10 underwent combined MVR with aortic valve replacement (AVR) and were reported to the Registry.

RESULTS

The 30 day mortality was 10.4% (9/86) in the MVR group and 10% (1/10) in the MVR and AVR group. The actuarial survival was 79.8, 64.1 and 40.7% at 1, 3 and 5 years, respectively, in the MVR group. Of the 10 early (30 day) deaths, 8 were due to cardiac reasons and 19 of the 28 late deaths were due to non-cardiac reasons. A total of 55 (57.2%) patients received a bioprosthetic valve implant and 41 (42.8%) patients received a mechanical valve implant. There was no difference in survival between the two groups.

CONCLUSIONS

The above results suggest that MVR in octogenarians produces a satisfactory early postoperative outcome and moderate medium-term benefit. There is no difference in survival between patients receiving bioprosthetic and patients receiving mechanical valve implants.

EEG changes during cardiopulmonary bypass surgery and postoperative neuropsychological deficit: the effect of bubble and membrane oxygenators

OBJECTIVE

Quantitative electroencephalography was used during cardiopulmonary bypass surgery to determine the point in time of most neuronal functional change which may result in postoperative neuropsychological deficit. It was also used to determine any relationship between quantitative electroencephalography changes and type of oxygenator used in surgery.

METHODS

We studied 61 coronary artery bypass graft patients. Anaesthesia included thiopental, fentanyl and N2O. Surgery was performed with hypothermic bypass (28 degrees C), arterial pressure of 50-70 mmHg, and alpha-stat, using bubble (Harvey 1700), or membrane (Cobe CML) oxygenators, both with arterial line filters (Pall 40 microns).

RESULTS

The main finding was a significant increase in delta power at the end of perfusion (P < 0.01), which showed a positive association with delta power before the start of perfusion. Marked quantitative electroencephalography change at the end of perfusion was not related to systemic hypotension, temperature, type of oxygenator, bypass time, or patient age. Intraoperative quantitative electroencephalography changes found in most patients were transient and could not be related to postoperative cerebral function. However, 16 of the 18 patients who had neuropsychological deficit 2 months after surgery, also had a significant quantitative electroencephalography change at the end of perfusion.

CONCLUSIONS

While no difference in anaesthetic technique was found between patients, the variation in quantitative electroencephalography power before perfusion may indicate a difference in individual response to anaesthetic. Usefulness of quantitative electroencephalography to predict postoperative cerebral functional deficit remains doubtful.

A pharmacokinetic study of sublingual aerosolized morphine in healthy volunteers

A pharmacokinetic study was undertaken to compare the pharmacokinetics of morphine after an intravenous dose with the pharmacokinetics after a sublingual dose administered from an aerosol. Plasma levels of morphine, morphine-3-glucuronide and morphine-6-glucuronide were measured in five normal volunteers after morphine administration by the intravenous route and from a novel sublingual pressurized aerosol formulation. The mean (+/- s.d.) bioavailability of the sublingual aerosol morphine was 19.7 +/- 6.7%. The morphine-3-glucuronide/morphine and the morphine-6-glucuronide/morphine ratios were 5.1 +/- 1.6 and 1.2 +/- 0.4, respectively, for the intravenous route and 28.3 +/- 11.3 and 5.2 +/- 1.4, respectively, for the sublingual route. The combined total areas under the plots of systemic concentration against time (AUC) for the metabolites after the two routes was not significantly different. When compared with published data for oral administration the results demonstrate that the sublingual aerosol morphine might provide an alternative to conventional methods of morphine delivery, and has similar pharmacokinetics to a sublingual morphine tablet. It has no particular pharmacokinetic advantages over oral morphine, except a potential for a faster onset of analgesia. Bioavailability, maximum plasma concentration, Cpmax, and the time at which the maximum plasma concentration is reached, Tmax, are equivalent to those for orally administered morphine.

Inhibition of proliferation and induction of apoptosis in juvenile myelomonocytic leukemic cells by the granulocyte-macrophage colony-stimulating factor analogue E21R

Juvenile myelomonocytic leukemia (JMML) is a malignancy that almost inevitably leads to death before adulthood. Chemotherapy has given disappointing results and a substantial number of patients relapse after bone marrow transplantation. A salient feature of this disease is that the JMML cells produce granulocyte-macrophage colony-stimulating factor (GM-CSF) spontaneously and survive and proliferate without exogeneous GM-CSF. Furthermore, JMML cells are hypersensitive to GM-CSF with addition of this cytokine leading to enhanced proliferation. We have recently generated a human GM-CSF analogue, E21R, that acts as a complete and selective GM-CSF receptor antagonist. We have now tested this molecule as a potential new agent to control the leukemic cell load in JMML with particular emphasis on its role in JMML cell survival. We found that E21R inhibited the spontaneous growth of JMML cells in vitro and caused their apoptosis in a dose- and time-dependent manner in seven of seven cases. In contrast, neither a neutralizing anti-GM-CSF monoclonal antibody (MoAb) nor a selective interleukin-1 (IL-1) receptor antagonist affected JMML cell survival. Furthermore, the apoptotic effect of E21R was seen even in the presence of interleukin-1 beta and tumor necrosis factor-alpha, which have also been implicated in the pathogenesis of JMML. The inhibitory effects of E21R on JMML cell growth and viability offer a novel approach to therapy in this lethal childhood leukemia.

Localization and targeting of isocitrate lyases in Saccharomyces cerevisiae

Native isocitrate lyase from castor bean and a C-terminally truncated variant were expressed in Saccharomyces cerevisiae under the control of a galactose-inducible promoter. Both forms of isocitrate lyase were targeted to the yeast peroxisomes. They co-fractionated with catalase on sucrose-density-gradient centrifugation of a post-nuclear supernatant prepared from cells grown on oleic acid plus galactose, but were found in the cytosolic fractions when the cells were grown under conditions that repress peroxisome formation. The endogenous S. cerevisiae isocitrate lyase was found solely in the cytoplasmic fractions, even under growth conditions that induce peroxisome proliferation. This result shows that the presence of isocitrate lyase in peroxisomes is not essential for a functional glyoxylate cycle. Although the heterologous enzyme was transported to peroxisomes it was not enzymically active. Immunocytochemical studies provide independent evidence that the plant enzyme is imported into the matrix of yeast peroxisomes.

Validation of the Applied Biosystems Prism 377 automated sequencer for the forensic short tandem repeat analysis

The Applied Biosystems (ABI) Prism 377 DNA sequencer has been evaluated in an attempt to increase the throughput of samples for short tandem repeat (STR) analysis, in both forensic casework and the UK National Criminal Intelligence DNA Database. The gel system assessed consisted of 0.2 mm, 4% acrylamide 6 M urea gels, with a well-to-read distance of 36 cm. Gels were run at a constant voltage of 3 kV and constant temperature of 51 degrees C. The run time of our second generation multiplex (SGM) STR system was achieved in less than 2 h. Rigorous validation has been performed on the instrument hardware and software. Complete resolution of 1 base differences was obtained, up to and beyond 350 bases; sizing precision across gels was more than 2-fold higher than the 373A and the sensitivity was increased by one third.

The therapeutic significance of pulse reverse osmosis

Pulse reverse osmosis (1) is a new theory of fluid balance and exchange which suggests that the mean blood pressure and osmotic gradient control fluid balance and that the pulse controls fluid exchange. In vitro testing has confirmed some of the physico chemical principles underlying the theory (2). The hypothesis suggests a relationship between mean capillary blood pressure and osmotic gradient. Imbalance in this relationship can be related to the development of hypertension, hypotension, oedema and shock. In an attempt to test this concept mean blood pressures and colloid osmotic pressures were measured and compared in a group of 50 healthy human volunteers. The results suggest a curvilinear correlation between the mean blood pressure and the COP.