Isoimmunity to Blood Platelets in the Rabbit

The occurrence of platelet isoimmunity was studied in rabbits sensitized by3 to 12 transfusions of homologous blood. Platelet isoimmunity in the transfused animals was detected and measured by two different technics: (1)determination of the survival of homologous platelets labeled in vivo withP³² and infused in the sensitized recipient rabbits; and (2) study of plateletagglutinins in the serum of the multitransfused animals.

It was found that:

1. After 3 to 12 blood transfusions, platelet sensitization, as determined byreduction in survival of homologous platelets in the transfused rabbits, occurred in most animals.

2. Survival of homologous specific platelets, i.e., platelets collected fromthe sensitizing donor and infused in the respective recipient, usually had lowervalues than the survival of homologous non-specific platelets.

3. Higher degrees of depression in survival of homologous platelets werefound in the rabbits which had received larger numbers of blood transfusions.

4. Platelet isoagglutinins could be found only in three of the five rabbitswhich had been sensitized with 12 blood transfusions and the test was stronglypositive in only one rabbit.

5. Repeat studies performed 2 months after the transfusions demonstratedpersistence of platelet isosensitization, while after 15 months isosensitizationhad greatly decreased; although in one rabbit a good degree of depression inhomologous platelet survival wa still present after this time interval.

These studies mainly demonstrate the high frequency of platelet isoimmunity in multitransfused rabbits and the inadequacy of the agglutinintest in the detection of even relatively severe degrees of platelet isosensitization.

Submitted on November 30, 1962 Accepted on February 9, 1963     

Evaluation of the Pulmonary Effects of HCl Using CO2 Challenges in Guinea Pigs

Evalution of the Pulmonary Effects of HCl Using CO₂ Challengesin Guinea Pigs. BURLEIGH-FLAYER, H., WONG, K.-L., AND ALARIE,Y. (1985). Fundam. Appl. Toxicol.. 5,97-985. Pulmonary effectsof inhalation exposures to hydrogen chloride were evaluatedduring and following exposure in male guinea pigs. During exposure,the respiratory rate and the time of onset of sensory or pulmonaryirritation as evidenced by the change in respiratory patternwere measured. HCl inhalation resulted in both sensory and pulmonaryirritation. The onset of sensory irritation took 6 min duringHCl exposures at 320 ppm but less than 1 min at 680, 1040, and1380 ppm. The onset of pulmonary irritation showed a concentration-responserelationship, the higher the concentration the earlier the onset.Following exposure to HCl, animals were evaluated using a pulmonaryperformance test based on their ventilatory response (respiratoryrate and tidal volume) during challenge with 10% CO₂. The maximalrespiratory frequency achieved during the CO₂ challenge waslower in the HCl-exposed animals than in the controls in a HOconcentration-dependent fashion, but HCl had no apparent effecton the maximal tidal volume achieved during CO₂ challenges.HCl exposure also affected baseline respiratory rate and tidalvolume of the animals after exposure. Impairments of the respiratoryfunction were also supported by evidence of morphological injuryin both the airways and the alveolar region.     

Ultrasonic Evaluation of the Carotid Bifurcation

Noninvasive tests for the detection of carotid occlusive disease have focused primarily on the indirect assessment of the internal carotid artery by the analysis of arterial pressure and flow. These tests can only detect the presence of flow-reducing lesions and occlusions; they cannot differentiate between these two entities. Also, the assessment of bilateral disease is difficult using these techniques. The introduction of ultrasonic methods has widened the diagnostic capabilities of noninvasive testing. Analysis of the velocity waveform envelope using zero-crossing detectors allows highly accurate identification of normal and severely diseased arteries. Used alone, however, this technique is limited in its ability to detect occlusions and provides no information on the energy content of the velocity spectrum. Furthermore, because it is often difficult to identify the sampling site with precision, the method does have limitations. The development of imaging techniques has helped to overcome this difficulty. While B-mode scanning appears promising, reliance on the image alone may be misleading. By producing an acoustic shadow, calcification may in fact hide a lesion of interest. Also, the similar acoustic characteristics shared by soft plaques, thrombi, and blood make it difficult to identify accurately soft plaques and occlusions. The addition of Doppler devices to ultrasonic imaging techniques has provided instruments that produce an image of the artery from which the flow information is collected. Methods involving the combination of a pulsed Doppler unit and an imaging system are particularly useful in detecting flow from discrete points within the vessel and prevent errors associated with flow disturbances near the wall. Errors associated with these techniques are usually the result of misidentification of vessels and tend to decrease as the examiner gains experience. Although auditory interpretation of the Doppler signal has produced good results, the quantitative analysis of the spectra represents a considerable improvement in diagnostic accuracy. Correct vessel identification and more precise quantification of the degree of narrowing can be achieved with this technique. In a research setting, the duplex technique provides a useful means of assessing the natural history of carotid artery disease before and after endarterectomy. Further improvements, such as the computer-based velocity waveform pattern recognition technique, have shown great potential in the objective evaluation of carotid disease. Although a great deal of work remains to be done, such techniques should provide us with a better understanding of and a more rational approach to the management of atherosclerotic disease at the carotid bifurcation.     

Expression of Complement Regulatory Proteins on Human Eggs and Preimplantation Embryos

PROBLEM : To investigate the relation between the complement system and reproduction, expression of complement regulatory proteins (C3b receptors and inhibitor of the membrane attack complex) were screened on unfixed human eggs and preimplantation embryos. METHODS : Unfixed unfertilized oocytes and preimplantation embryos obtained from an in vitro fertilization program were stained by indirect immunofluorescence using monoclonal antibodies raised against membrane cofactor protein, (MCP or CD46), decay accelerating factor (DAF or CD55), protectin (CD59), human C3b/C4b receptor (CR1 or CD35), and major histocompatibility complex class I antigen (MHC class I). RESULTS : CD55 and CD59 were both expressed by the plasma membrane of unfertilized oocytes and pre-implantation embryos. CD46 was not expressed by unfertilized oocytes but appeared at the 6-to-8 cell stage embryo when human gene expression first occurs. CD35 and MHC class I antigens were not expressed at all on oocytes and preimplantation embryos. CONCLUSIONS : Selective expression of complement regulatory proteins (DAF and protectin) associated with the lack of MHC class I antigens may represent an immune protective mechanism by which human oocytes and preimplantation embryos escape complement-mediated damage during their travel through the female genital tract. Furthermore, participation of these complement regulatory proteins including MCP in cell to cell interaction during fertilization and/or implantation cannot be excluded.     

Contribution of a Pacemaker Bradycardia Detection Algorithm in the Study of Patients with Carotid Sinus Syndrome

While carotid sinus syndrome (CSS) is often suspected as a cause of syncope in the elderly, whether it represents an indication for cardiac pacing may remain uncertain. Bradycardia algorithms included in pacemakers are now able to establish a precise relationship between spontaneous asystole and occurrence of symptoms and strengthen the indication for permanent pacing. This study included seven men and three women (70.5 +/- 7.3 years of age) who, over an average period of 54.1 +/- 17 months, had suffered from syncope (12.6 episodes/patient) and presyncope (11.2 episodes/patient) attributed to pure cardioinhibition (2 patients) or mixed CSS (8 patients). Other sources of symptoms were excluded by thorough clinical evaluations, including Holter monitoring, echocardiography, and electrophysiological testing. All patients received a CHORUS 6234 pacemaker, the memory of which includes a dedicated bradycardia detection algorithm capable of storing atrial and ventricular chains, and date and time of the last ten pauses and/or bradycardic events. After a initial period of 14.7 +/- 8 months, during which symptoms were suppressed, the bradycardia algorithm was activated. From then on, a cumulative increase in the number of patients presenting with diurnal pauses was measured (1 month, n = 0; 3 months, n = 6; 9 months, n = 7; 2 years, n = 8). Fourteen episodes of diurnal asystole were recorded. The mean duration of the longest episodes of spontaneous ventricular standstill was 6,319 +/- 1,615 ms and was due to sinoatrial block (n = 7), atrioventricular block (n = 5), and a combination of both (n = 2). In conclusion, activation of the CHORUS bradycardia algorithm allowed confirmation of the appropriateness of permanent pacing in a majority of patients suffering from CSS.     

Impact of Radiofrequency Characteristics on Acute Pulmonary Vein Reconnection and Clinical Outcome After PVAC Ablation

Impact of Radiofrequency Characteristics . Objective: The objective was to study the impact of radiofrequency (RF) characteristics on acute pulmonary vein reconnection (PVR) and outcome after PVAC ablation. PVI with additional ablation of PVR (PVI + PVR) was compared to PVI‐only. Methods: In 40 consecutive patients, after PVAC‐guided PVI, adenosine and a 1‐hour waiting time were used to unmask and ablate acute PVR (PVI + PVR group). RF‐characteristics and 1‐year AF freedom were compared post hoc to 40 clinically matched patients undergoing PVI only (PVI‐only group). Custom‐made software was used to assess RF characteristics of the PVAC applications needed to obtain baseline PVI. Results: There was no difference in clinical characteristics or baseline RF‐profile between both groups. Acute PVR was observed and ablated in 38 of 160 veins (24%). AF‐freedom after PVI + PVR was higher than PVI (85% vs 65%, P < 0.05). Within the PVI group, comparing patients with and without AF‐recurrence, the percentage of PVAC applications with high T° (>48°) but low power (<3W) was higher (28 ± 18% vs 11 ± 11%, P < 0.0001). Within the PVI + PVR group, when comparing PVs with and without PVR, the percentage of low power/high T° PVAC applications was also higher (27 ± 13% vs 13 ± 15%, P < 0.0001). Conclusions: (1) After PVAC ablation, 24% of PVs exhibit acute reconnection. Additional ablation of reconnection improves clinical outcome. (2) Acute reconnection as well as clinical recurrence of AF are characterized by PVAC ablation with a considerable number of applications with high temperature but low power. (3) If PV isolation is obtained with low power applications, a consistent use of both adenosine and waiting time is required. (J Cardiovasc Electrophysiol, Vol. 24, pp. 290‐296, March 2013)     

Individual Variability of the Cutaneous Larva Migrans (CLM) Incubation Period

Abstract: Whether the high variable incubation period of cutaneous larva migrans depends on the parasite or other host factors remains unknown. Two brothers were contaminated simultaneously, but had 15‐ and 165‐day incubation periods, respectively, suggesting a possible influence of host factors. A long incubation period does not rule out cutaneous larva migrans in patients with creeping eruption.     

Surgical Interruption of a Left Inferior Vena Cava Following the Transfemoral Implantation of a Permanent Pacing Lead

This report describes the case of a patient in whom, after an unsuccessful attempt through the subclavian vein, a permanent pacing lead was inserted through the femoral vein and a left inferior vena cava with azygos continuation. The procedure was followed 4 months later by a pulmonary embolism complicating a right femoroiliac thrombosis. The patient was successfully treated by a percutaneous lead extraction procedure combined with an inferior vena caval surgical interruption. (PACE 1997; 20[Pt. I]:1365-1366)     

Transcranial Measurement of Cerebral Microembolic Signals During Endocardial Pulmonary Vein Isolation: Comparison of Three Different Ablation Techniques

Introduction: Isolation of the pulmonary veins (PVI) using high ablation energy is an effective treatment for atrial fibrillation (AF) with a success rate of 50–95%; however, postoperative neurological complications still occur in 0.5–10%. In this study the incidence of cerebral microembolic signals (MES) as a risk factor for neurological complications is examined during 3 percutaneous endocardial ablation procedure strategies: segmental PVI using a conventional radiofrequency (RF) ablation catheter, segmental PVI using an irrigated RF tip catheter, and circumferential PVI with a cryoballoon catheter (CB).
Methods and Results: Thirty patients underwent percutaneous endocardial PVI. Ostial isolation was performed in 10 patients with a conventional 4-mm RF catheter (CRF) and in 10 patients with a 4-mm irrigated RF catheter (IRF). A circumferential PVI was performed in 10 patients with a CB. Transcranial Doppler (TCD) monitoring was used to detect MES in the middle cerebral arteries.
The total number of cerebral MES differs significantly among the 3 PVI groups; 3,908 cerebral MES were measured with use of the CRF catheter, 1,404 cerebral MES with use of the IRF catheter, and 935 cerebral MES with use of the CB catheter.
Conclusion: This study demonstrates a significant difference in cerebral MES during PVI with 3 different ablation procedures. The use of an irrigated RF and a cryoballoon produces significantly fewer cerebral MES than the use of conventional RF for a PVI procedure, suggesting a higher risk for neurologic complications using conventional RF energy during a percutaneous PVI procedure.     

Removal of Endocardial Defibrillation Leads

Two patients, each with an endocardial defibrillation lead system (Endotak O62), required lead removal; one because of chronic lead infection and the second because of spurious shocks caused by lead insulation damage. Neither lead could be removed by simple traction. The defective lead was removed by a combination of catheterization techniques including a steerable ablation catheter and traction, both under general anesthesia. The lead with the insulation defect was rapidly removed with a locking stylet, suggesting that endocardial lead defibrillating leads can be removed similarly to pacemaker leads, thus avoid thoracotomy.