Evaluation of the polarographic technique for assay of the viability of freeze-dried BCG vaccine: I. The polarographic technique.

In this paper, a new assay based on oxygen uptake assessed by polarography was evaluated with the aim of establishing the viability of freeze-dried BCG vaccine. An oxygen electrode possessing a temperature sensor was designed for this purpose. The polarographic method used had several advantages, particularly its rapidity and use of small amounts of biological material. These advantages are ideal for quality control of BCG vaccine.

Evaluation of the polarographic technique for assay of the viability of freeze-dried BCG vaccine: II. Viability of the vaccine assessed by polarography, Warburg respirometry and colony counting.

A comparative study of the viability of 34 lots of freeze-dried BCG vaccine has been carried out using an oxygen electrode polarographic technique, Warburg respirometry and colony counting. There were no statistical differences between the results obtained with the polarographic and Warburg techniques. Both methods gave reliable and similar results and showed a positive correlation (r = 0.8615). Comparison between the polarographic and colony-counting methods showed a positive correlation (r = 0.6530); for comparison between the Warburg and colony-counting methods, the correlation value was r = 0.6868. All the tests were significant at the level of alpha = 0.05. The advantages of the polarographic technique are that it is much less time- and material-consuming than other methods. It is a reliable, inexpensive and convenient method for BCG vaccine quality control.

Does the oxygen tension of coronary sinus blood reflect myocardial oxygen tension?

Coronary sinus blood oxygen tension (CSpO2) and myocardial oxygen tension (MpO2) were measured simultaneously during cardiac ischemia and reperfusion. Oxygen tension was measured using a polarographic method. Myocardial ischemia caused a reduction (5 +/- 1.5%; P less than 0.05) in CSpO2 and a decrease (56.5 +/- 10.1%; P less than 0.001) in MpO2. Reperfusion induced a rapid but transient increase (35.9 +/- 4.3%; P less than 0.001) in CSpO2 above the basal state while MpO2 returned gradually to the basal state. These results indicate that CSpO2 is of little value for the detection of changes in myocardial oxygen metabolism during the initial phase (seconds) of cardiac reperfusion.

[Influence of proximal gastric vagotomy on the esophageal high pressure zone in dogs]. / Influência da vagotomia gástrica proximal sobre a zona de alta pressão esofagogástrica do cão.

The influence of parietal cell vagotomy (PCV) on esophagogastric high pressure zone (HPZ) (pressure and length) was studied in 30 dogs. The animals were divided in 3 groups: group 1, 10 dogs submitted to PCV with gastric denervation until the esophagogastric junction; group 2, 10 dogs submitted to PCV with gastric denervation into esophagogastric junction and 3 cm above this; group 3 (control), 10 dogs submitted to laparotomy only. In the postoperative period (immediate and later) it wasn't observed any alteration of pressure and length of esophagogastric HPZ in three studied groups.

Is coronary sinus blood oxygen tension behavior determined by myocardial oxygen tension variation during cardiac reperfusion?

The relationship between coronary sinus blood oxygen tension (CSPO2) and myocardial oxygen tension (MPO2) variations during cardiac ischemia and reperfusion was studied in anesthetized open-chest dogs. Oxygen tension was measured by a polarographic method. Ischemia resulted in a slightly decreased CSPO2 and a more pronounced reduction of MPO2. After reperfusion the CSPO2 rose rapidly and transiently before it returned gradually to the control level. By contrast, during the recovery period, the MPO2 increased slowly, with recovery occurring long after the peak of CSPO2. These data suggest that during the reperfusion phase, the CSPO2 variation is probably due to opening of the myocardial arteriovenous shunts instead of an increase of flow through the myocardial capillary bed.

Changes in myocardial and coronary sinus blood oxygen tension induced by asphyxia and reoxygenation.

1. This study analyzes variations of oxygen tension induced by asphyxia in the myocardium (MpO2) and coronary sinus blood (CSpO2) of the anesthetized open-chest dog. Oxygen tension was measured polarographically and arterial blood pressure and coronary blood flow were recorded simultaneously. 2. Asphyxia increased arterial pressure and coronary blood flow but decreased both MpO2 and CSpO2. 3. During the reoxygenation phase, arterial pressure and coronary flow decreased gradually. Reoxygenation induced a rapid but transient increase in CSpO2 above control levels. In contrast, MpO2 returned gradually to the basal state. 4. The mechanism(s) involved in the differential effects of asphyxia followed by reoxygenation on MpO2 and CSpO2 remain to be elucidated.

Polarography of Walker tumor submitted to radiotherapy.

A polarographic study of oxygen was done in 57 rats inoculated with Walker 256 tumor and platinum electrode implanted in muscle and in tumor. The goal of the research was the study of oxygen in tumor before and after irradiation. Tumor growth caused a decrease in tumoral oxygen. Oxygen was always lower in the tumor than in the muscle. Radiotherapy with 2000 rad (but not with 1000 rad) increased oxygen in the tumor.

A technique for the determination of the available oxygen in living carp (Cyprinus carpio) muscle.

A polarographic method for the measurement of the available oxygen in the muscle of living carp by the use of a platinum microelectrode is proposed. The oxygen and the reference electrodes were assembled in a single insertion piece which was implanted in the muscle of a living carp maintained in a special experimental chamber. Curves for normal oxygen levels corresponding to air-saturated water, as well as to a carbogene-saturated water, were obtained. The method can be considered adequate for the measurement of tissue oxygen in living fishes.

[Variability of pHmetric parameters in the esophagogastric junction in dogs]. / Variabilidade de parámetros pHmétricos na junção gastroesofágica do cão.

The authors studied the variability of pHmetric parameters of the gastroesophageal junction in dog. The research was done in six dogs, that studied in five sections, according to four techniques (intermittent pull-through technique, continuous pull-through technique, continuous push-through technique and rapid pull-through technique), with four determinations in each of them. The pHmetric determinations of stomach, oesophagus and gradient of esophagogastric pH presented little variability (coefficient of variation less than 50%). The constituent parameters of the pHmetric profile and the pHmetric lenght of the gastroesophageal junction presented high variability (coefficient of variation bigger than 100%), except the C2 segment. Taking into consideration the little variability the authors propose the study of C2 segment in the analysis of the pHmetric profile of the gastroesophageal junction.

[Esophagogastric junction in the dog. Study of some pHmetric technics]. / Junção gastroesofágica no cão. Estudo de algumas técnicas pHmétricas.

The authors' carried out a pHmetric study of stomach, esophagus and gastroesophageal junction in dog, using four techniques: intermittent pull-through technique, continuous pull-through technique, continuous push-through technique and rapid pull-through technique. The study was done in six adult male dogs. Each animal was studied in five sessions, having been undergone 16 examinations and having been done 4 examinations of each technique. The intermittent pull-through technique (TPI) proved to be the most adequate for the pHmetric study, because it propitiates better interaction conditions between electrode and environment. Of the techniques of continuous dislocation, the continuous push-through technique (TEC) presented the most satisfactory results, having the electrode presented little latency. The continuous pull-through technique (TPC) has its application on the dependence of the pull speed; it was observed that the less the speed the less the latency of the electrode. The rapid pull-through technique (TPCR) doesn't permit an adequate interaction between electrode-environment, in consideration of the rapidity of the examination.