Perfusion fixation of the newborn opossum: equipment and techniques.

A 30-gauge cannula was used to perfuse fixative through the fragile heart of a newborn opossum. The cannula was gently maneuvered into the heart and held in place with a specially designed manipulator. The flow rate of the fixative was regulated with an infusion set connected to the cannula.     

Comparison of two techniques for obtaining endometrial bacteriologic cultures in the mare

The endometria of 39 mares were cultured simultaneously using a swab guarded with a double cannula and distal, teflon plug and an unguarded swab with a single, open cannula. Sheep blood (5%) agar, Mac-Conkey's agar, and Sabourad's agar media were innoculated with each swab. The presence of bacterial or fungal growth was determined after 24 and 48 hours of aerobic incubation at 37 C. There were significantly more plates that failed to yield bacterial or fungal growth when streaked with swab specimens obtained with the guarded cannula than when streaked with those obtained with the unguarded cannula. It was concluded that while culturing the endometrium of mares for bacteria or fungi, the use of a guarded instrument consisting of a double cannula with a closed end will result in the recovery of fewer contaminants; therefore, it will be more likely to result in a more accurate representation of uterine bacterial and fungal flora.     

Improved method for bile collection in unrestrained conscious rats.

We describe an improved method for continuous collection of bile from unrestrained rats. Use of an externally accessible, continuous-loop cannula when cannulating the common bile duct allows for full recovery from anesthetic effects and maintenance of a normal bile salt pool until the cannula loop is cut. Bile resulting from the cut cannula is diverted into a surgically implanted glass collection vessel and removed periodically via an externalized sampling port. Bile flow over a 24-hour collection period averaged 0.98 +/- 0.04 ml/hr (Mean +/- SEM, n = 9) with no gross pathological changes noted upon necropsy. This technique offers the capability of reestablishing conditions as close to physiologic as possible postsurgery to minimize potential artifacts during bile collection.     

A simple non-surgical method of intrabronchial instillation for the establishment of respiratory infections in the rat.

A technique involving intubation of weanling rats for intrabronchial instillation of infectious material has been developed to produce a respiratory infection model suitable for experimental infection studies. The technique is performed simply with the use of a metal cannula and an intravenous plastic cannula, and dispenses with the need for illumination, laryngoscopy and extensive manipulation of the animal.     

Ultrasound-guided cannulation of the caudal vena cava in the bovine for selective sampling of ovarian effluent

The accuracy of real-time, B-mode ultrasonography was assessed in the visualization and placement of the cannula tip, cranial to the entrance of the ovarian veins as they enter the caudal vena cava of the bovine. A cannula containing a wire guide was introduced into the coccygeal vein via a 14-gauge needle, and was then directed cranially into the caudal vena cava. Once the caudal vena cava was successfully cannulated (7 of 14 cows), ultrasonography allowed for the visualization of the cannula in 7 out of 7 cows. The tip of the cannula was successfully placed cranial to the entrance of the ovarian effuent into the vena cava in 6 of these 7 animals using ultrasound guidance. This was confirmed using progesterone or prostaglandin F(2alpha) radioimmunoassay (RIA). The primary limitation to this technique was the initial catherization of the coccygeal vein which was not achieved in 7 of 14 cows attempted in this study. Successful cannulation was limited to large framed Holstein cows that had at least one calf. Results from this study indicate that real-time, B-mode, ultrasonography is an effective tool for the visualization and accurate placement of the cannula tip within the caudal vena cava. This finding could have implications for research in ovarian hormonal physiology in the cyclic, postpartum or anestrous cow.     

Reformative cannula electrodes for His bundle electrogram recording in isolated rat hearts

His bundle electrogram (HBE) recording is an important method for the study of the atrioventricular conduction system. However, the current HBE recording methods in isolated animal hearts have some disadvantages, such as unstable recording due to the difficulty in fixing electrodes as a result of intense heart beat, the small amplitude of the His signal or the possibility to destroy the integrity of heart structure. To overcome these disadvantages, we designed and manufactured reliable, inexpensive and easy-made bipolar cannula electrodes, which combine the functions of Langendorff-perfusion aortic cannula and recording electrodes. With the cannula electrodes, the operation of HBE recording becomes easier and clearer; hence, more stable recordings can be obtained in isolated rat hearts.     

Cannulation of the jugular vein in mice: a method for serial withdrawal of blood samples

We have developed and validated a method that allows serial drawing of blood samples in freely moving mice using a cannula that is inserted via the jugular vein into the right atrium of the heart. The cannula was tunnelled subcutaneously to the head of the animal and attached to the skin by sutures, together with a metal spring, which was covered with PVC tubing for protection of the outer part of the cannula. Samples of blood up to 250 micro l could be taken at serial time points. The blood volume in the circulation was maintained by replacement with an equal volume of blood obtained from donor animals. The applicability of this method of blood sampling for pharmacokinetic purposes was validated by comparing plasma concentrations-time curves in six cannulated animals after receiving an intravenous bolus dose of 10 mg/kg of the anti-cancer agent docetaxel versus the results in plasma samples obtained by cardiac puncture of non-cannulated mice. The presented method may lead to improved pharmacokinetic data produced from a reduced number of mice.     

Variability in intraosseous pressure induced by saline flush of an intraosseous cannula by multiple practitioners

Intraosseous cannulation is an accepted means to achieve vascular access when peripheral venous access is not available. It is common practice to flush the intraosseous cannula with saline prior to establishing infusions. The objective of this study was to evaluate changes in intraosseous pressure during the flush procedure and to assess the variability of pressure changes induced by different practitioners. Two intraosseous cannulas were placed in an isolated cadaveric femur collected from a swine. Intraosseous pressure and the rate of change in pressure were recorded continuously during a series of saline flushes into a distal femoral intraosseous cannula by 21 members of the veterinary research staff at the authors' institution. Median peak intraosseous pressures exceeded 600 mmHg, and an inverse relationship was noted between peak intraosseous pressure and the duration of flush. Bone marrow fat emboli were grossly evident in flush effluents and their presence was confirmed by microscopic examination. Until the practitioners were informed of the pressure changes induced by the intraosseous cannula flush, few had appreciated the magnitude of the pressures that they had generated, suggesting that an instrumented intraosseous flush preparation like the one used in this study may prove useful as a training tool for flush procedures.     

The use of cerebral ventriculography for verification of intracerebroventricular cannula placement in the live rat

A technique using cerebral ventriculography for verification of intracerebroventricular cannula placement in the live rat is described. A radiopaque contrast medium, diatrizoate meglumine, was injected into the right lateral ventricle through a cannula stereotaxically implanted into the brain. Radiographic visualization of the radiopaque contrast material in the lateral ventricle and the subarachnoid space verified cannula placement. Transient muscular spasms were observed in about 38% of the injected rats but no lasting changes were observed in the behavior or appearance of these rats.     

A simple method for intragastric administration of powdered materials to rats

A simple technique was used for administration of powdered material directly into the stomach of rats. A commerically available positive displacement pipetting device was filled by tamping the cannula tip into the powder. The contents of the cannula could then be discharged into the stomach by insertion of the cannula via the esophagus. The device required only minor modifications prior to its use in this manner. The technique provided a means of accurate dosing of insoluble materials and eliminated the difficulties encountered in the oral administration of suspensions.     

The effect of sampling technique on acid-base balance and other blood parameters in the sheep.

The effect of 4 sampling routines--venipuncture, intravenous cannula, intravenous cannula following the administration of a tranquiliser (xylidino dihydrothiazine hydrochloride), intravenous cannula following exercise--were compared. Blood pH and base excess values were similar after venipuncture and cannula sampling, but higher (P less than 0 with 05) after the administration of the tranquiliser and lower (P less than 3 with 05) following exercise. Blood haemoglobin, haematocrit and lactate levels followed this pattern, while plasma protein levels were similar for all treatments except after exercise, where they were higher (P less than 0 with 05). The recovery of various blood parameters to normal values after a period of exercise was also studied: acid-base balance had returned to near normal within 60 min, while haemoglobin and haematocrit levels had returned to normal within 10 min.     

Characterization of In Vivo Dopamine Release as Determined by Brain Microdialysis After Acute and Subchronic Implantations: Methodological Aspects

Infusion of tetrodotoxin (TTX) through the dialysis membrane and perfusion with calcium-free Ringer solution (calcium depletion) were used to evaluate the dopamine release determined by in vivo brain dialysis. Several hours after implantation, the dopamine release recorded by the U-shaped cannula did not respond to calcium depletion and was only partly (approximately 50%) TTX dependent. The half-life of the TTX-independent dopamine overflow was determined to be 2 h. In contrast, when a transstriatal cannula was used, the dopamine output displayed calcium and TTX dependency. Differences in the dimensions of the two types of probes are a likely explanation for the observed effects. Twenty-four hours after implantation, both types of cannula fulfilled the criteria of calcium and TTX dependency. The results indicate that infusion of TTX-containing or calcium-free Ringer solution can be used to estimate the functional damage caused by the implantation of the cannula.     

Adrenergic activation of the liberation of corticotropin-releasing hormone (CRH41) in the median eminence of unanesthetized rats

To shed light on the persistent controversy concerning the role of central adrenergic systems in the corticotropic axis, we measured the effects of adrenaline on the release of IR-rCRH41 into a push-pull cannula stereotaxically implanted in the median eminence. Eight days before experimentation, the cannula was implanted, under deep anesthesia, at which time a standard cannula was additionally placed in the lateral ventricle (i.c.v.). The rats were not anesthetized during the main experiment. An i.c.v. injection of 5 microliter of solvent only slightly affected the release of CRH41, whereas an i.c.v. infusion of 1.4 micrograms adrenaline bitartrate under the same conditions led to an instantaneous, but short-lived, 8-fold rise in the CRH41 release above baseline. The data provide the first demonstration of a central stimulatory effect of adrenaline on the secretory activity of CRH41 producing neurons, in unanesthetized, free-moving rats.     

Chronic intratumoral chemotherapy of a rat tumor with cisplatin and fluorouracil

In order to demonstrate the feasibility and efficacy of intratumoral chemotherapy, brain tumors in rats were treated by direct infusion of cisplatin or fluorouracil. Each animal was initially implanted in the midline cerebellum with a chronic stainless-steel cannula, and 2 weeks later 1 X 10(5) 9L cells were injected through the cannula. 8 days after tumor cell transplantation, a small implantable pump containing drug, or saline as a control, was connected up to the same cannula, and the solution was pumped into the tumor region for 7 days. The results showed that both drugs produced statistically significant increases in survival as compared to the controls.     

Quinton-Scribner Cannulas for Hemodialysis—Review of Four Years' Experience

Data on a study group of 52 maintenance hemodialysis patients cannulated with Quinton-Scribner cannula in a four-year period were analyzed. The average period of dialysis was 11.8 months with either a pumped coil or a pumpless Kiil artificial kidney system. One hundred and forty-five cannulations were performed. The mean arterial cannula survival was 7.8 months and the mean venous cannula survival was 7.2 months. The exceptional longevity of cannula survival occurred despite the high incidence of atherosclerotic changes at operation and the advanced mean age (47 years) of the patients. The cannula longevity may be partially related to the technique used and to meticulous surgical care given the patient before and after cannulation.Complications from cannulation included two deaths, one from septic pulmonary embolism of Staphylococcus origin, and one from acute Pseudomonas endocarditis. A total of 36 infections of cannulas were recognized, the majority being due to Staphylococcus aureus, but 28 percent being secondary to Gram-negative bacteria.     

A technique for chronic intragastric drug administration in the rat

An improved method for chronic intragastric delivery of drug solutions in the rat is described. The cannula can be easily constructed while the implantation is a simple and a problem-free procedure. Animals suffered no ill effects and resumed normal weight gain profiles after the operation. Since this is a direct stomach cannulation technique, the problems associated with the nasopharyngeal method are avoided. The cannula was tested by administering methadone and observing the characteristic depression of operant responding for food reinforcement. Using the cumulative records, it was possible to detect the onset of drug effect which was found to be about 10 minutes. The cannula is relatively durable and has remained patent in some animals for as long as 10 months without maintenance.     

The use of a silastic shield to protect an externalized biliary cannula

A simple shield made of a folded silastic sheet is described for the protection of the externalized portion of a permanent biliary cannula in rats. Advantages of this shield are its light weight, flexibility, transparency, and ease of resealing for repeated interruption of hepatobiliary circulation. Since the shield is positioned around rather than being a segment of the cannula, a single length of tubing can be used.     

Special cannulas for the puncture of implanted catheter port systems

The Huber-Point cannula is generally recommended for portal puncture. Two comparative studies are published that show no advantage in using Huber-point cannulas. This has been verified by technical investigations. A new type of non-coring cannula is described.     

Gynecomastia: suction lipectomy as a contemporary solution

Suction lipectomy is adapted for the correction of gynecomastia. Previous attempts using suction lipectomy for gynecomastia still required the use of sharp dissection for removal of the glandular breast tissue as well as excision of redundant skin. With this new technique, gynecomastia is corrected solely with the use of suction lipectomy. The technique is successful if the gynecomastia is due to excess fat or parenchymal hypertrophy. A 7-mm cannula is inserted first, to remove the adipose tissue. Then a 2.4-mm cannula is used to remove the glandular and ductal tissue. The 7-mm cannula is then reinserted to remove subareolar parenchyma and to make final contour adjustments. The surrounding subcutaneous tissue is easily undermined to avoid a saucer deformity and to allow for skin contraction. Patients return to full activities in 48 hours. A compressive garment is worn for 4 to 6 weeks. The results of 10 patients are discussed.     

Three Years' Experience with Bypass Cannulae for Chronic Hemodialysis

In 14 patients over the past three years, “bypass” cannulae have been inserted to relieve obstruction in cannulae used for chronic hemodialyses. Experience with these patients has prompted changes resulting in improved technique.Clotting was the major cause of cannulae failure and infection was the second most important cause. Other causes of failure included: venous atheroma, cannulae extrusion, aneurysms of the vessel at the cannulae tips, obstructive vegetation on the vessel wall, calcium deposits on the vessel wall, and thrombi on the vein walls.The mean survival time was improved from 1.9 months in 1963-1964 to over 9.0 months in 1965-1966. The longest surviving cannula set was two years and the shortest one week.It is considered that the most important factors contributing to increased cannula survival are improved cannula care by patients and staff, the use of angiography for accurate diagnosis, and prompt anticoagulation if atheromatous stenosis of the venous component is encountered.