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.     

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.     

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.     

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.     

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.     

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.     

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.     

The metabolism of dopamine in rat caudate nucleus can be increased by in vivo “dialysis” perfusion cannulae

The development of dialysis cannula techniques coupled with high performance liquid chromatography and electrochemical detection (HPLC-EC) has provided a means to continuously sample extracellular fluid from deep brain structures $\text{in vivo}$. The present studies show that with HPLC-EC analysis of the acid metabolites of dopamine (DA) and 5-hydroxytryptamine (5-HT) in samples from dialysis cannulae implanted in the caudate nucleus of anaesthetized rats, it is possible to determine the time course of the response of dopamine- and 5-HT containing neurones to administration of monoamine oxidase inhibitors and haloperidol. The tissue concentrations of the DA and 5-HT metabolites were also determined at the conclusion of each individual experiment in both the caudate nucleus containing a cannula and in that without a cannula. In perfusion experiments where no drug was administered the content of the DA metabolites, but not that of the 5-HT metabolite, were significantly elevated in the caudate nucleus containing the cannula as compared with the contralateral tissue. These increases occurred whether the cannula was perfused or not, suggesting that the presence of the cannula may have been causing a lesion which altered the activity of the DA neurones. These results emphasize the importance of tissue analysis in conjunction with the dialysis experiments, especially where perfusion sample contents of the monoamine metabolites are being measured as a reflection of the effects of behavioural manipulation or drug treatment on endogenous neuronal activity.     

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.     

A simple technique for rapid implantation of a permanent cannula into the rat brain ventricular system.

A simple, rapid method of implantation of a permanent cannula into the ventricular system of the rat brain was developed using polyethylene tubing. Intraventricular injections were performed on nonrestrained, conscious animals. This cannula was used repeatedly during several weeks.     

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 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.     

Maintenance of silastic–teflon shunts for intermittent haemodialysis

The occurrence of infection in the tissues surrounding external arteriovenous shunts was studied and die important relationship of pyogenic infection to clotting was confirmed. The local application of fusidic add tulle and lanolin greatly reduced the occurrence of both infection and clotting and the need for cannula replacement.Urokinase used for declotting shunts when standard procedures had failed, restored blood flow whether dotting was related to infection or to local vascular factors. This treatment is not advised when clotting is associated with a local abscess, as it may make cannula replacement necessary. Severe local vascular factors, such as metastatic calcification, Raynaud''s phenomenon, and venous stenosis, may lead to poor blood flow, so that despite clot lysis elective cannula replacement or the creation of a subcutaneous arteriovenous fistula is required.     

A technique for repeated sampling of pure cerebrospinal fluid from the conscious rabbit

For the study of drug pharmacokinetics' a reliable method for repeated sampling of uncontaminated cerebrospinal fluid (CSF) from a conscious rabbit was established. The subdural space was punctured between a spinous processes of the lumbar vertebrae. A catheter was inserted through a cannula and pushed up to the region of the cisterna magna. After removing the cannula, the distal end of the catheter was sealed and placed subcutaneously until the onset of the experiments. Ten days after the insertion, samples of clear and colorless CSF up to 1 ml could be withdrawn.     

Effect of outflow pressure on lung lymph flow in unanesthetized sheep

Studies in anesthetized animals have shown that the flow rate from lung lymphatics (QL) depends on the pressure at the outflow end of the vessels (Po). We tested this in unanesthetized sheep prepared with chronic lung lymph cannula. We measured QL with the lymph cannula held at various heights above the olecranon and calculated Po as the height + QL X cannula resistance. QL decreased with increases in Po (delta QL/delta Po = -8.2 +/- 6.4 microliter X min-1 X cmH2O-1, mean +/- SD). We increased QL by raising left atrial pressure or infusing Ringer solution or Escherichia coli endotoxin and found that QL was even more sensitive to Po (delta QL/delta Po = -32 +/- 22). Cannula resistance caused a 9-70% reduction in QL. Changes in QL caused by increasing Po were not associated with changes in lymph protein concentration for up to 330 min. This indicates that increases in Po shunt lymph away from cannulated vessels but do not substantially effect microvascular filtration rate. The shunted lymph may flow into other vessels or collect in the lung. We conclude that QL does not accurately represent microvascular filtration rate because it depends on the cannula resistance and position at which the investigator chooses to place the cannula.     

Long-term infusion of nonphysiologic solutions into brain parenchyma: effects of pH, osmolarity, and flow rate

The effects of long-term (3-day) infusion of nonphysiologic solutions into brain parenchyma were investigated in male Fischer (F344) 344 rats. Two weeks prior to infusion, a guide cannula was placed into the striatum, substantia nigra, or hippocampus. Solutions were infused continually for 3 days at flow rates of 0.03 (129.6 microl total) or 0.10 (432 microl total) microl/min. Four days after infusion, rats were euthanized and the brain was removed and processed for histologic evaluation. Rats that received cannula implants alone had the usual mechanical damage induced by implantation of the cannula. The brain regions that received 0.9% saline, pH 5.0 or pH 9.0 buffer at the two aforementioned flow rates had only minor evidence of tissue damage adjacent to the infusion site that was similar to that attributable to mechanical damage from the cannula implants. Brain tissue infused with distilled water or 1.8% saline also had modest effects of the solutions similar to the usual mechanical damage induced by the infusion cannulae. In contrast, contamination of the infusion sites was seen to induce inflammation. Data from these studies support the hypothesis that nonphysiologic solutions can be used to deliver compounds into brain parenchyma, without the infusion solutions themselves causing excess damage to brain tissue.     

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.     

Role of the pulvinar-lateralis posterior nucleus complex (P-LP) in the experimental epilepsy of the cat

The ability of the pulvinar-lateralis posterior nucleus complex (P-LP) to evoke epileptic activity when stimulated, was studied in 20 adult cats. Twelve animals were analyzed after they recovered from the surgical procedure (chronic model). In seven of them a cannula with electrodes was implanted in the P-LP and one twisted bipolar electrode was placed ipsilaterally in the following structures: hippocampus, superior colliculus, caudate nucleus and cerebral cortex. Through the cannula Na penicillin was injected. The electrodes allowed both to stimulate and to record the electrical activity. In the remaining five cats, the cannula was implanted in hippocampus in order to compare its sensitivity to generate epileptic activity to that of P-LP. Another group of eight cats were surgically implanted and studied in the same day (acute model). In four of them the cannula was placed in the P-LP through the temporal pathway, to avoid crossing the hippocampus and the ventricle. In another four, penicillin was injected in the P-LP after suctioning the cerebral cortex and the hippocampus overlying the former structure. Epileptic activity could be induced in P-LP and it spread rapidly to hippocampus and after a while to the other implanted structures. This was observed both with penicillin and electrical stimulation. The sensitivity of P-LP to generate epileptic activity was lower than that of the hippocampus. In particular, it was necessary to use two to ten times more penicillin and three times the electrical current intensity in the P-LP as compared to the values needed in the hippocampus. These results are discussed in view of the controversial problem about the ability of the thalamus to generate and spread epileptic activity.     

A Novel Rat Model to Study the Role of Intracranial Pressure Modulation on Optic Neuropathies

Reduced intracranial pressure is considered a risk factor for glaucomatous optic neuropathies. All current data supporting intracranial pressure as a glaucoma risk factor comes from retrospective and prospective studies. Unfortunately, there are no relevant animal models for investigating this link experimentally. Here we report a novel rat model that can be used to study the role of intracranial pressure modulation on optic neuropathies. Stainless steel cannulae were inserted into the cisterna magna or the lateral ventricle of Sprague-Dawley and Brown Norway rats. The cannula was attached to a pressure transducer connected to a computer that recorded intracranial pressure in real-time. Intracranial pressure was modulated manually by adjusting the height of a column filled with artificial cerebrospinal fluid in relation to the animal’s head. After data collection the morphological appearance of the brain tissue was analyzed. Based on ease of surgery and ability to retain the cannula, Brown Norway rats with the cannula implanted in the lateral ventricle were selected for further studies. Baseline intracranial pressure for rats was 5.5±1.5 cm water (n=5). Lowering of the artificial cerebrospinal fluid column by 2 cm and 4 cm below head level reduced ICP to 3.7±1.0 cm water (n=5) and 1.5±0.6 cm water (n=4), a reduction of 33.0% and 72.7% below baseline. Raising the cerebrospinal fluid column by 4 cm increased ICP to 7.5±1.4 cm water (n=2) corresponding to a 38.3% increase in intracranial pressure. Histological studies confirmed correct cannula placement and indicated minimal invasive damage to brain tissues. Our data suggests that the intraventricular cannula model is a unique and viable model that can be used to study the effect of altered intracranial pressure on glaucomatous optic neuropathies.     

Simple validation for the hepatic venous cannula implanted chronically in conscious rats

A method for the detection of vena caval contamination in blood taken from hepatic venous cannulas in conscious rats was described. The procedures included 1) bolus injection of tritiated water (50 microCi) through a cannula into the abdominal inferior vena cava and 2) continuous blood sampling (less than 0.2 ml) from the hepatic venous cannula for 2 min into a 180-cm piece of Tygon tubing, starting concurrently with tracer injection. The washout of tritium was determined from samples in 15-cm sections of Tygon tubing. Because circulation from the inferior vena cava to the hepatic vein is interceded by the systemic circulation, the washout of tritium from a valid hepatic venous cannula should resemble the pattern determined elsewhere in the systemic circulation. In the current study, the reference systemic washout was determined in the superior vena cava of a group of rats similarly injected with tritiated water in the inferior vena cava. The maximum of tritium washout derived from a valid hepatic venous cannula should fall in the range encompassed by one standard deviation of the mean of the maximum of the reference (1,400 to 1,930 cpm/sample). The maximum of the washout pattern derived from the invalid cannula, which lay adjacent to the site of injection, was expected to exceed this range. On the basis of these criteria, hepatic blood flow (HBF) was determined by sulfbromophthalein (BSP) extraction in groups of rats with valid and invalid cannulas. HBF in rats with valid hepatic venous cannulas was 2.58 +/- 0.15 in the conscious state and 2.76 +/- 0.26 ml.min-1.g wet wt-1 in the ketamine-anesthetized state.(ABSTRACT TRUNCATED AT 250 WORDS)