Use of Telemetered Electrograms in the Assessment of Normal Pacemaker Function

The facility of direct real-time endocardial electrogram recording offered by newer pacemaker models can be helpful in the assessment of normal pacemaker function. Confirmation of the main hallmarks of sensing (amplitude, slew rate, and timing of the electrogram) can be achieved. Assessment of pacing capture also can be made; techniques for further analysis using external signal averaging can enhance this. The measurement of atrial and ventricular electrograms by telemetry has led to alterations in the protocol used at implantation to allow for the input impedance of the sensing circuit of the pacemaker. Accurate measurements of retrograde VA conduction times and confirmation of normal upper rate limit behavior of ODD pacemakers can be achieved simply and reliably using telemetered electrograms from the permanent pacemaker system.     

Inadequate Erythropoietin Response to Anaemia in HIV Patients: Relationship to Serum Levels of Tumour Necrosis Factor-Alpha, Interleukin-6 and Their Soluble receptors

Severe anaemia is a frequent complication in advanced HIV infection. In our study we investigated the interaction between cytokine network, HIV infection and erythropoietin (Epo) response with increasing anaemia levels. No correlations could be established between circulating tumour necrosis factor (TNF)-alpha and any of the examined parameters. However, a negative correlation was found between haemoglobin values and soluble TNF receptor levels (sTNF-R-I: r  = −0.54; P  < 0.001; sTNF-R II: r  = −0.47; P  < 0.001) as well as interleukin-6 levels ( r  = −0.29; P  < 0.001). In contrast, no significant increase in log[Epo], counterbalancing haemoglobin decline and paralleling the rise in sTNF receptors, was found. In patients classified as stage III, according to the Centers for Disease Control (CDC) classification, the erythropoietin response was significantly more impaired than in patients from CDC groups I and II ( P  < 0.001). The results of this study suggest that similar to its action in vitro , activation of the TNF/TNF-R system may impair erythropoietin production in HIV-associated anaemia. Due to the brief half-life of TNF-α, this activation is particularly reflected by elevations of soluble TNF receptor levels.     

Incremental Value of Three-Dimensional Echocardiography Over Transesophageal Multiplane Two-Dimensional Echocardiography in Qualitative and Quantitative Assessment of Cardiac Masses and Defects

In the present study, we compared three-dimensionally (3-D) reconstructed images with multiplane two-dimensional (2-D) transesophageal echocardiographic (TEE) images in 17 patients with various cardiac masses and defects. To overcome the problem of making measurements from 3-D reconstructed images, we carefully "dissected" the 3-D dataset using paraplane and anyplane 2-D sections, which were then used to obtain the maximum sizes of the cardiac masses and defects. Of the 15 vegetations and 9 abscesses detected by 3-D TEE in 7 patients, only 8 (53%) vegetations and 4 (44%) abscesses were detected by multiplane 2-D TEE (P < 0.02). Also, the exact anatomical location, shape, geometry, and extent of various cardiac masses and defects were more clearly delineated by 3-D than 2-D TEE. The maximum dimensions of cardiac masses and defects were larger by 3-D than by 2-D TEE in 17 (89%) of the 19 lesions available for comparison (P < 0.002). In addition, 3-D TEE correlated more closely than 2-D TEE when compared to surgical measurements in three patients in whom they were available. Thus, it would appear that in several instances, the exact size of the cardiac lesion could only be assessed by analysis of the 3-D volumetric dataset. Out preliminary study has demonstrated the superiority of transesophageal 3-D reconstruction over multiplane 2-D TEE in both qualitative and quantitative assessment of various cardiac mass lesions and pathological defects.     

Surgical Treatment of Double Inlet Ventricle ("Single Ventricle")

The surgical techniques described are the result of an evolution over a number of years in the performance of the septation operation and the modified Fontan-Kreutzer repair for patients with double inlet ventricles. Those with associated pulmonary stenosis are best palliated by a classical Blalock-Taussig or Goretex shunt if an operation is required during the first few years of life and later, between two and four years of age, definitive repair by the modified Fontan-Kreutzer operation is advised. Although controversial, we prefer the use of a large nonvalved right atrial-pulmonary artery connection. Ventricular septation remains the best definitive surgical option when pulmonary stenosis is absent or mild. It is contraindicated by severe pulmonary vascular disease and also by less than moderate ventricular enlargement. The need for concomitant AV valve replacement and the use of an extracardiac conduit are associated with increased hospital mortality in our experience. Infants identified during the first year of life who do not have pulmonary stenosis are a difficult subset to manage. If the VSD and subaortic area is large and unobstructed, pulmonary artery banding early in life will control pulmonary vascular resistance and from this standpoint, permit these patients to become ultimately suited to a modified Fontan-Kreutzer repair. Unfortunately, ventricular hypertrophy usually results from pulmonary artery banding and has been associated with higher hospital mortality at the time of definitive repair. When pulmonary artery banding is undertaken for this subset, debanding and definitive repair seems best advised at about two years of age. Pulmonary artery banding is well known to accelerate the development of subaortic stenosis by spontaneous progressive restriction of the VSD. This results in small ventricular cavity size and increased ventricular hypertrophy, which are incremental risk factors for increased hospital mortality by either definitive procedure. When the VSD or subaortic area is narrow and the patient is identified during the first year of life, isolated pulmonary artery banding is inappropriate. The surgical options for these patients include Ebert's two-stage management program consisting of the initial placement of a loose partial septation patch with concomitant pulmonary artery banding, and later debanding and complete septation. Alternatively, a trial of primary complete septation may be warranted, or the use of a procedure consisting of division of the main pulmonary artery with distal closure and anastomosis of the proximal portion to the side of the ascending aorta, coupled with a systemic-pulmonary artery shunt.     

Scintigraphic visualization of intrathecal liposome biodistribution

Background: Liposomes containing local anaesthetics have been administered intrathecally and in the epidural space. Poor attention has been given to the pharmacokinetics of liposomes as drug carriers. Therefore, we observed the biodistribution of liposomes after intrathecal injection in rats by scintigraphic imaging during 24 h.
Methods: We administered ⁹⁹Tc-labeled multilamellar (MLV) and small unilamellar vesicles (SUV) of defined size and volume dispersities into the cerebrospinal fluid at the lumbar level. Those vesicles were free of contamination by radiolabeled colloids as visualized by light and electron microscopy and of neurotoxic products from phosphatidylcholine hydrolysis and peroxidation, both during the preparation process and after 24 h incubation in cerebrospinal fluid at 37°C in vitro.
Results: SUV immediately diffused from the lumbar site of injection to the head and were cleared between 1 and 24 h after injection. MLV were cleared more slowly from the spinal space and appeared in the head region 1 h after injection where they accumulated up to 24 h. These differences were explained in terms of vesicle sizes and volumes. SUV with 0.05 μm diameters were rapidly absorbed into the blood through the arachnoid granulations. In contrast, particles larger than the upper size limit of the arachnoid granulations permeability (±8 μm) could accumulate in the head with a slow elimination rate.
Conclusion: This difference in clearance from the intrathecal space outlines the importance of defining the size of the liposomes, the distribution of a tracer or a drug inside the liposomal preparation, the chemical stability and the absence of toxic degradation products of liposome formulations before clinical use.     

Platelet size analysis in the quality assurance of platelet concentrates for transfusion

Summary The platelet distribution width (PDW) as analysed on standard haematology cell counters is an indicator of size dispersion in the platelet population. Using a Sysmex® E-2500 analyser platelet concentrates prepared for transfusion showed an increase in PDW over storage. This increase correlated strongly with in vitro indicators of platelet viability (pH and response to osmotic stress). PDW may thus be useful for clinical haematology laboratories as a predictor of the viability of transfused platelets. The same instrument gave a measure of the largest platelets in the platelet population as a large cell ratio (P-LCR). For platelet concentrates with less than 8 × 10¹⁰ platelets/unit, the P-LCR at preparation was negatively associated with the end of storage pH, indicating that the presence of large platelets increases the production of lactic acid and accelerates the platelets’ metabolic storage lesion. This information may be useful in determining storage conditions for single donor platelets harvested by apheresis.     

Rapid steady-state analysis of blood-brain glucose transfer in rat

A new kinetic analysis of blood-brain glucose transport is described, based on a steady-state model that takes account of cerebral blood flow, mean capillary glucose concentration, and cerebral metabolic rate. The maximal rate (T_max) and half-saturation constant (K_m) of glucose transport from blood to brain were determined in rats by measuring the rate of blood-to-brain glucose transfer at different blood glucose concentrations. Each determination lasted 20 seconds. For whole-brain, T_max and K_m averaged 258±33 (S.E.) μmol (100 g)^-1 min^-1 and 5.9±1.6 (S.E.) mmol 1^-1, respectively. The regional variations were insignificant. The new approach permits kinetic parameters to be measured locally in brain in rapidly changing functional states.     

A NOVEL DRB1*0801 HAPLOTYPE CARRYING DRB3*0202 FOUND IN A GERMAN PEDIGREE

DRB1*08 haplotypes have not been known to carry a DRB3 gene. We have found a patient suffering from liver disease who has a novel HLA haplotype of DRB1*0801 with DRB3*0202 as established by family segregation. These two genes were confirmed by sequencing. DR8 and DR52 antigen specificities were serologically detected, indicating expression of these genes.     

Serology and Genetics of Te58(W18) and Other Specificities Included in the 4c Complex

In order to clarify the distinction between three antigens included in the 4c complex, correlation coefficients, gene frequencies, haplotype frequencies and linkage disequilibrium parameters are given for HL-A5, Te50 = W5 and Te58 = W18 in three different ethnic groups.
Te58 = W18 is shown to be an allele of the second segregant series by data from family studies by correlation coefficients, by the lack of triplets, and by the goodness of fit according to the Hardy-Weinberg law.