Acute choke zone effects: Lessons from radioactive and fluorescent microspheres in a pig model muscle flap.

BACKGROUND: Choke vessels dilate and contract to regulate blood flow between adjacent arterial angiosomes. In skin flap surgery, when arterial inflow to an angiosome is ligated, choke vessels allow blood supply from an adjacent angiosome. In muscle flap surgery, the vascular anatomy is analogous to skin flaps; however, while it is established that the choke vessels will fully dilate irreversibly after two to three days, no study has yet analyzed the acute changes in each vascular region immediately following ligation of one pedicle. OBJECTIVE: To establish whether the choke vessels open or close immediately following ligation of a pedicle, and how this change affects blood flow in the adjacent proximal and distal vascular regions. METHODS: Radioactive and fluorescent microspheres in a pig model were used to study the regional intramuscular blood flow in each anatomical zone of a rectus abdominis flap. Blood flow measurements for each zone were calculated relative to the entire muscle at preligation, ligation and various times (15 min to 90 min) postligation. RESULTS: There was no statistically significant difference in blood flow across choke zones as a result of ligation. This signifies that the choke vessels do not significantly dilate to produce a statistically significant measureable change in blood flow. CONCLUSIONS: Given these results and previous literature findings, the anatomical presence of choke vessels in a muscle is the strongest determining factor for acute flap viability in surgery.

HISTORIQUE: Les vaisseaux anastomotiques se dilatent et se contractent pour réguler le débit sanguin entre les angiosomes artériels adjacents. Dans le cadre d'une chirurgie par lambeau cutané, lors de la ligature du débit artériel vers un angiosome, les vaisseaux anastomotiques assurent un débit sanguin en provenance d'un angiosome adjacent. L'anatomie vasculaire est alors analogue aux lambeaux cutanés. Cependant, bien qu'il soit établi que les vaisseaux anastomotiques se dilatent pleinement et de manière irréversible au bout de deux ou trois jours, aucune étude n'a encore analysé les changements aigus de chaque région vasculaire immédiatement après la ligature d'un pédicule. OBJECTIF: Établir si les vaisseaux anastomotiques s'ouvrent ou se ferment immédiatement après la ligature d'un pédicule et examiner l'effet de ce changement sur le débit sanguin des régions proximales et distales adjacentes. MÉTHODOLOGIE: Les chercheurs ont utilisé les microsphères radioactives et fluorescentes d'un porc pour étudier le débit sanguin intramusculaire régional de chaque zone anatomique d'un lambeau du grand droit. Ils ont mesuré le débit sanguin de chaque zone par rapport au muscle entier avant la ligature, au moment de la ligature et à divers moments (de 15 à 90 minutes) après la ligature. RÉSULTATS: Il n'y avait pas de différence statistiquement significative du débit sanguin dans les diverses zones anastomotiques après une ligature. Ainsi, les vaisseaux anastomotiques ne se dilatent pas au point de produire un changement du débit sanguin pouvant être mesuré de manière statistiquement significative. CONCLUSIONS: Compte tenu de ces résultats et des conclusions de publications scientifiques, la présence anatomique de vaisseaux anastomotiques dans un muscle est le principal déterminant de viabilité aiguë d'un lambeau lors d'une chirurgie.

99mTc-bioquin-7CA, a potential new hepatobiliary scanning agent.

The complex 99mTc-Sn-8-hydroxyquinoline-7-carboxylate (99mTc-bioquin-7CA) was investigated in animals as a potential hepatobiliary scanning agent. Following intravenous injection, the complex was found to localize in the liver rapidly and in the gallbladder in 5--15 min; after 15 min it was excreted into the biliary tract with a high degree of specificity. Urinary excretion was negligible, reducing scan interference from the kidneys. Distribution studies in mice compared well withe localization of activity observed in rabbit scans. Preparation of the complex was rapid and simple; stannous ion was used as the reducing agent.

Evaluation of formamidine sulfinic acid and other reducing agents for use in the preparation of Tc-99m labeled radiopharmaceuticals.

Various reducing agents have been evaluated for their potential usefulness in the preparation of 99mTc labeled radiopharmaceuticals for use in nuclear medicine. Adequate labeling of various radiopharmaceuticals was accomplished using formamidine sulfinic acid. Nitrogen-purging of solutions is not required, which is an advantage for in-house preparation. Tagging requires heating, however, so heat-labile material cannot be used. Various compounds that could not be labeled when stannous chloride was used, could be tagged with 99mTc when formanidine sulfinic acid was used as the reducing agent.

Multiple line source array for SPECT transmission scans: simulation, phantom and patient studies.

UNLABELLED: Accurate attenuation and scatter corrections in quantitative SPECT studies require attenuation maps of the density distribution in the scanned object. These can be obtained from simultaneous emission/transmission scans. METHODS: A new method has been developed using a multiple line source array (MLA) for transmission scans, and its performance has been investigated using computer simulations and experimental data. The activity in the central lines of the MLA was higher than at the edges of the system, so that more transmission photons would be directed toward the thicker parts of the human body. A series of transmission-only and simultaneous emission/transmission studies were performed for different phantom configurations and human subjects. Attenuation maps were generated and used in reconstruction of attenuation-corrected emission images. RESULTS: The mu coefficients for attenuation maps obtained using the MLA system and simulated and experimental data display no artifacts and are qualitatively and quantitatively correct. For phantoms, the agreement between the measured and the true value of mu for water was found to be better than 4%. The attenuation-corrected emission images for the phantom studies demonstrate that the activity in the heart can be accurately reconstructed. A significant qualitative improvement was also obtained when the attenuation correction was used on patient data. CONCLUSION: Our results indicate that the MLA transmission source can be used in simultaneous transmission/emission imaging to generate accurate attenuation maps. These maps allow for performing an object-specific, attenuation correction of the emission images.

An evaluation of radiocolloid sizing techniques.

Techniques for sizing radiocolloids are reviewed. The small size range (1-100 nm) of many radiocolloids and their polydispersity limit the choice of the technique used. To compare several techniques directly, the particle size of Technetium-99m sulfide colloid was studied using Nuclepore filtration, ultracentrifugation and electron microscopy. The last of these was adopted as the method of choice. Using this technique, the particle size and shape of colloids below 100 nm can be accurately determined. Technetium-99m antimony sulfide colloid and indium-113m hydroxide were then examined by electron microscopy, and the chemical nature of the particles was determined by x-ray fluorescence analysis. Results resolved the size discrepancies reported in the literature and demonstrated the importance of identifying the chemical nature of the particles under examination.

Pharmacologic interventions for prevention of spinal cord injury caused by aortic crossclamping.

The efficacy of pharmacologic agents for prevention and control of oxygen-derived free radical damage in ischemia-reperfusion injury of the spinal cord was assessed in a swine model of thoracic and thoracoabdominal aortic crossclamping. Animals were exposed to 30 minutes of ischemia that induced lethal, irreversible injury and paraplegia. The experimental groups were as follows: group A (n = 7), control group, receiving no pharmacologic intervention; group B (n = 7), deferoxamine 50 mg/kg/day administered intravenously over 3 to 4 hours before ischemia; group C (n = 7), allopurinol pretreatment 50 mg/kg/day for 3 days; and group D (n = 7), superoxide dismutase 60,000 units administered with 50,000 units before removal of the aortic crossclamp and 10,000 units over 10 minutes of reperfusion. Proximal hypertension was controlled with sodium nitroprusside and volume depletion. The methods of assessment were neurologic by a modified Tarlov criteria and blood flow by radiolabeled microspheres. Results of blood flow assessment confirmed a true ischemic episode of 30 minutes for all animals in all groups. The blood flow fell significantly during ischemia (p less than 0.01) and a hyperemic response was evident in the early reperfusion period. All animals in control group A were paraplegic. The group B (deferoxamine) results were superior; 85% had grade III function on a modified Tarlov scale, with animals in the group standing and even walking with difficulty. Only one animal in this group had good movements of hind limbs but was unable to stand or walk. Neurologic recovery was limited in the allopurinol group (group C), with 85% showing slight neurologic recovery with limited movement of the hind limbs. The animals in the superoxide dismutase group (group D) all had good recovery, with strong motor response of hind limbs, but were not able to stand. In summary, the results of this experimental protocol confirmed the possible role of oxygen-derived free radicals in the pathophysiology of spinal cord injury, induced by aortic crossclamping. Moreover, it proved that ischemia-reperfusion injury could be altered by pharmacologic interventions.

Additive effect of allopurinol and deferoxamine in the prevention of spinal cord injury caused by aortic crossclamping.

Fourteen domestic swine were divided into two groups. Group A (n = 7) was the control group, in which no pharmacologic intervention was applied. In group B (n = 7), the ischemic-reperfused spinal cord was treated with the combination of allopurinol (50 mg/kg/day for 3 days before the day of operation) and deferoxamine (Desferal, 50 mg/kg administered intravenously over 3 to 4 hours). The administration of deferoxamine was completed 1 hour before crossclamping. The crossclamp was placed on the descending aorta just distal to the left subclavian artery for 30 minutes. Proximal hypertension was controlled with sodium nitroprusside and volume depletion. Methods of assessment included an evaluation of the neurologic status of the animals by quantitative Tarlov criteria, blood flow by radiolabeled microspheres, and histologic examination of the spinal cord. All animals in the control group, group A, were completely paraplegic with 0% recovery by Tarlov criteria at 24 hours after the removal of the crossclamp. In contrast, all animals in group B, in which the combination of allopurinol and deferoxamine was used, completely recovered (100% recovery by Tarlov criteria), and at 24 hours after the ischemic episode they were able to walk with no difficulty and had intact sensation. Functional parameters of these animals fully correlated with the morphologic findings. Widespread acute neuronal injury and vacuolation of neuropil were observed in the control group of animals. In contrast, animals in group B showed much less pronounced morphologic changes after the same period of ischemia. In summary, the combined use of these agents significantly (p < 0.001) reduced the incidence of paraplegia induced by aortic crossclamping with 82% additivity.

Assessment of myocardial metabolic state after hypothermic heart preservation for transplantation utilizing radioiodinated free fatty acid imaging.

Myocardial turnover of 15-p-iodo(123I)-phenylpentadecanoic acid (123I-IPPA) was assessed in 14 swine experiments before and after orthotopic heart transplantation. Two preservation techniques were used: simple hypothermic storage (group 1; n = 7) and a perfusion technique (group 2; n = 7) with pressure maintained at 28 cm H2O (20 mm Hg) and a myocardial temperature of 8 to 10 degrees C. Hearts in both groups were initially perfused with hypothermic isosmolar potassium cardioplegic solution to acquire immediate diastolic arrest. The perfusate in group 2 was an extracellular formulation supplemented with glucose, mannitol, insulin, and oxygen. The ischemic interval for both groups was 6 hours including orthoptic transplantation. Pretransplant and posttransplant planar gamma imaging was performed using 3 to 5 mCi 123I-IPPA. Fatty acid turnover was assessed using time-activity curves analyzed by monoexponential least squares curve fitting generating t1/2 (half-lives in minutes). Increases in t1/2 were observed in hearts of both groups after transplantation, that is, lateral (290% +/- 72% and 104% +/- 49% increase, p = 0.03), septal (140% +/- 34% and 39% +/- 29% increase, p = 0.02), and apical (273% +/- 111% and 133% +/- 44% increase, p = 0.06) walls within groups 1 and 2, respectively. We conclude that 123I-IPPA turnover is useful in assessing the immediate metabolic state of posttransplant myocardium. It can also be concluded that preservation techniques based on continuous hypothermic perfusion are better able to maintain normal metabolic substrate utilization immediately after transplantation than are simple hypothermic storage techniques.

Presence of WBC, decreased strength, and delayed soreness in muscle after eccentric exercise.

The purposes of this study were to assess the presence of 99mTc-labeled white blood cells (WBC) in exercised muscle compared with nonexercised muscle over time and to determine the time course of delayed onset muscle soreness (DOMS) and eccentric torque in 10 female subjects. A pretest was followed by 300 eccentric repetitions of the right quadriceps. DOMS and eccentric torque were measured at 2, 4, 20, 24, 48, and 72 h postexercise. Eccentric torque was also tested at 0 h. Radionuclide images of both quadriceps were taken at 2, 4, 20, and 24 h postexercise. The presence of 99mTc-WBC in the exercised muscle was significantly greater (P < 0.001) than in the nonexercised muscle. Eccentric torque declined at 0 and 24 h postexercise. DOMS peaked at 24 h postexercise. The presence of 99mTc-WBC in the exercised muscle in the first 24 h suggests that acute inflammation occurs as a result of exercise-induced muscle injury. The bimodal pattern of eccentric torque supports the hypothesis that more than one mechanism is involved.

Kinetic analysis and comparison of uptake, distribution, and excretion of 48V-labeled compounds in rats.

Vanadium has been found to be orally active in lowering plasma glucose levels; thus it provides a potential treatment for diabetes mellitus. Bis(maltolato)oxovanadium(IV) (BMOV) is a well-characterized organovanadium compound that has been shown in preliminary studies to have a potentially useful absorption profile. Tissue distributions of BMOV compared with those of vanadyl sulfate (VS) were studied in Wistar rats by using 48V as a tracer. In this study, the compounds were administered in carrier-added forms by either oral gavage or intraperitoneal injection. Data analyzed by a compartmental model, by using simulation, analysis, and modeling (i.e., SAAM II) software, showed a pattern of increased tissue uptake with use of 48V-BMOV compared with 48VS. The highest 48V concentrations at 24 h after gavage were in bone, followed by kidney and liver. Most ingested 48V was eliminated unabsorbed by fecal excretion. On average, 48V concentrations in bone, kidney, and liver 24 h after oral administration of 48V-BMOV were two to three times higher than those of 48VS, which is consistent with the increased glucose-lowering potency of BMOV in acute glucose lowering compared with VS.

Colonic migrating motor complexes (CMMCs) in the isolated mouse colon.

Spontaneous contractions were recorded from the circular muscle layer at three sites along the isolated mouse colon. The interval between contractions was approximately 4.5 min. The mean duration of the contractions ranged from 26 sec in the distal colon to 45 sec in the proximal colon. Contractions migrating more than half the length of the colon were termed colonic migrating motor complexes (CMMCs). Over 90% of tissues demonstrated migration predominantly in an aboral direction. Hyoscine (10(-6) M) decreased the amplitude of the CMMCs by at least 40% but had no significant effect on the interval or duration of the CMMCs. Nifedipine (10(-6) M) significantly decreased the amplitude of the CMMCs by 95% but did not alter the duration or the interval between the CMMCs. Hexamethonium (5 x 10(-4) M) and tetrodotoxin (TTX; 2 x 10(-6) M) abolished all CMMC activity. TTX increased the resting tone of the preparations. Nitro-L-arginine (10(-4) M) increased the resting tone of the preparations and significantly decreased the interval between the CMMCs by approximately 80% but had no significant effect on the duration of the CMMCs. The results suggest CMMCs migrate predominantly in an aboral direction and are neurogenic in origin. Nitric oxide may be involved in maintaining inhibition of the muscle between CMMCs.

Electrophysiological analysis of the actions of pituitary adenylyl cyclase activating peptide in the taenia of the guinea-pig caecum.

The actions of pituitary adenylyl cyclase activating peptide (PACAP) on membrane potential and conductance were investigated in the taenia of the guinea-pig caecum. The possible role of PACAP in inhibitory transmission was also investigated. Membrane potentials of smooth muscle cells were measured by intracellular microelectrodes, in the presence of hyoscine and nifidepine (both 10(-6)M. To determine conductance changes, current was passed from external plate electrodes using the technique of Abe and Tomita (1968). PACAP-27 caused a concentration dependent hyperpolarization of the muscle with a maximum of 12-15 mV at 10(-6)M. The hyperpolarization caused by PACAP was associated with a substantial increase in membrane conductance. The hyperpolarization was abolished by apamin (10(-6)M), a blocker of small conductance, calcium-dependent, potassium channels, and was reduced to about 50% by suramin (10(-4)M), which is an antagonist of P2 receptors for purines. The hyperpolarization was not reduced by tetrodotoxin (2 x 10(-6)M), suggesting PACAP acts directly on the muscle. With continued exposure to PACAP, the hyperpolarization decayed back to resting membrane potential after several minutes, possibly due to receptor desensitization. Inhibitory junction potentials (IJPs) were markedly reduced in amplitude in the period of presumed receptor desensitization to PACAP, were abolished by tetrodotoxin, but were not affected by suramin. Apamin abolished the IJP and revealed a small excitatory junction potential. This study implies that PACAP released from nerve fibres in the taenia caeci hyperpolarizes the muscle via an opening of apamin-sensitive potassium channels. The action is probably through type I PACAP receptors.

In vitro evaluation of the effect of metered-dose inhaler administration technique on aerosolized drug delivery.

The administration of aerosolized metered-dose inhalers (MDIs) to mechanically ventilated patients is labor intensive due to the large number of activations required and the currently recommended 30- to 60-second "wait and shake" between each puff. No studies have been published that assess the relationship between this delay between puffs and drug delivery. To address this issue, we conducted an in vitro, randomized, single-blind study using fenoterol MDI containing technetium-99m pertechnetate. Four modes of MDI administration were tested in triplicate by random sequence. Eight activations of the MDI were performed for each mode according to the following procedures: rapid succession (5 sec apart); 30-second intervals and shaking MDI between two rapid activations; 30-second intervals and shaking between each activation; and 60-second intervals and shaking between each activation. Two closed in vitro systems were designed to collect and measure the radiolabeled aerosol. In the first system, the MDI was activated into a plastic collection container; with the second system, the MDI was administered through an aerosol holding chamber with attached circuit filter positioned on the inspiratory line of the ventilator circuit. Sixty-second intervals between each activation were not tested with the second system. Radioactivity was measured before and after each mode of testing. No difference was found between the various modes of administration other than a 14% decrease in the amount of radioactivity released with the 60-second waiting period between puffs, compared with their rapid succession when using the plastic collection container system. Our results support the hypothesis that the delay after each activation of a MDI may not be necessary.

Biological evaluation of 2-fluoro-2-[123I]iodo-mannose (FIM): biological evaluation of FIM.

This paper describes the biodistribution of a radio-iodinated analog of fluorodeoxyglucose (FDG). 123I-2-fluoro-2-iodo-mannose (FIM) was investigated as a potential single photon emission tomography (SPECT) imaging agent. We also compare the results with the observed distribution of the classical PET agent 18F-FDG and newly developed 18F-difluorodeoxyglucose (DFDG). Following radioiodination, the final product was stable in-vitro for 24 hrs. Mice showed a rapid blood clearance and deiodination of the 123I-FIM reflected by high stomach and thyroid uptake. Comparison with 18F-FDG and 18F-DFDG revealed a large discrepancy between the 18F labeled sugars and the 123I-FIM biological distribution. The iodinated product was not found to be a metabolic marker for in-vivo studies.

Extending the lifetime of anticoagulant oligodeoxynucleotide aptamers in blood.

We have investigated (123)I and (125)I DNA aptamer analogs of anticoagulant DNA aptamers to thrombin exosite 1 and exosite 2 for thrombus imaging potential. Two severe problems are rapid clearance from circulating blood and blood nuclease. With aptamers (unlike antisense) the nucleotide analogs used in polymerase chain reaction-selection cycles also must be used in the radiotracer. We investigated 3'-biotin-streptavidin (SA) bioconjugates of the aptamers to alleviate these problems. Blood nuclease assays and biodistribution analysis were used in the mouse and rabbit. We found that 3'-biotin protected the aptamers significantly from blood nuclease in vitro, but it did not slow in vivo clearance. In contrast, the 3'-biotin-SA bioconjugates were resistant to blood nuclease in vitro and were also longer-lived (10-20 times) in vivo. Bioconjugate aptamers retained affinity for thrombin. Two solutions emerge: 1) In noncirculating blood (within a thrombus) 3'-biotin extends aptamer lifetime, whereas 2) in circulating blood (the transport medium), where more aggressive clearance is encountered, 3'-SA extends aptamer lifetime.

Potential 99mTc radiopharmaceuticals for renal imaging: tris(N-substituted-3-hydroxy-2-methyl-4-pyridinonato)technetium(IV) cations.

A series of monocationic complexes of N-substituted-3-hydroxy-2-methyl-4-pyridinones labeled with technetium(IV)-99m have been evaluated in vivo as potential radiopharmaceuticals. The pyridinones have different substituents at the ring nitrogen atom: ethyl, i-propyl, i-butyl, benzyl, phenyl, p-methoxyphenyl, 3-butoxypropyl and cyclohexyl. Biodistribution studies of the 99mTc complexes have been carried out in rabbits and mice. High kidney uptake and retention of the radionuclide has been shown in rabbits and mice with the cationic complexes of 3-hydroxy-1-(p-methoxyphenyl)-2-methyl-4-pyridinone and 1-(cyclohexyl)-3-hydroxy-2-methyl-4-pyridinone. These 99mTcL3+ compounds appear to be morphologic renal agents.

Performance of the dynamic single photon emission computed tomography (dSPECT) method for decreasing or increasing activity changes.

Radionuclide imaging is now widely used whenever functional information is required. We present a new approach to dynamic SPECT imaging (dSPECT method) that uses a single slow rotation of a conventional camera and allows us to reconstruct a series of 3D images corresponding to the radiotracer distribution in the body at various times. Using simulations of various camera configurations and acquisition protocols, we have shown that this method is able to reconstruct washout half-lives with an accuracy greater than 90% when used with triple-head SPECT cameras. Accuracy decreases when using fewer camera heads, but dual-head geometries still give an accuracy greater than 80% for short and 90% for long half-lives and about 50-75% for single-head systems. Dynamic phantom experiments have yielded similar results. Presence of attenuation and background activity does not affect the accuracy of the dSPECT reconstructions. In all situations investigated satisfactory dynamic images were produced. A preliminary normal volunteer study measuring renal function was performed. The reconstructed dynamic images may be presented as a three-dimensional movie showing movement of the tracer through the kidneys and the measurement of the regional renal function can be performed. The time-activity curves determined from this dSPECT data are very similar to those obtained from dynamic planar scans.

Beta-methyl-15-P-[123I] iodophenyl-pentadecanoic acid and thallium-201 in the assessment of myocardial perfusion defects.

The purpose of this investigation was to examine the ability of beta-methyl-15-P-[123I]-iodophenyl-pentadecanoic acid (beta 123IPPA) and thallium-201 to assess the ischemic risk zone associated with myocardial infarction. The hearts of mongrel dogs were infarcted by ligating the left anterior descending coronary artery and at 6 h post infarction injected with thallium-201 (2 mCi; scanning time 30 mins) followed by beta 123IPPA (3 to 5 mCi; scanning time 30 mins). Scintigraphic assessment of the perfusion defect yielded perfusion defect size (percentage of whole slice), which was then compared to the defect when assessed by tetrazolium staining. Myocardial ratios were calculated to assess differences in localization between tracers. Any differences noted may affect identification of the area at risk following acute myocardial infarction. A slice-by-slice comparison of perfusion defect size for scintigraphic methods and histochemical method showed no significant difference between beta 123IPPA and thallium-201. The mean ratio for myocardial defect size expressed as beta 123IPPA/thallium-201 was 1.03 +/- 1.29. Enzymatic analysis demonstrated significant increases in creatine kinase (160.33 +/- 46.44 to 5030.6 +/- 2238 U) and creatine kinase-MB% (31.85 +/- 15.11 to 82.99 +/- 8.14%) post infarction (P less than 0.05 in both cases). Elevated ST segments were also seen in all dogs post infarction. It can be concluded that the combined use of beta 123IPPA and thallium-201 does not allow the identification of the ischemic risk zone (percentage area at risk) often associated with myocardial perfusion defects. Problems continue to exist with image resolution and border demarcation.

Interstitial lymphoscintigraphy for lymphatic mapping in surgical practice and research.

Lymphoscintigraphy is a nuclear medicine technique that gives morphologic and functional information about the lymphatic system. The size of radiopharmaceutical used is a critical factor for it to have acceptable characteristics of uptake by the lymphatics and migration to lymph nodes. A small particle (10-100 nm) with opsonins or a unique surface is required for uptake by lymph-node macrophages. It can be prepared for application with a simple filtering process producing a predictable size distribution and number of particles for the scan. The radiation dose is safe for the patient and staff. Technetium-99m sulfur colloid is readily available and approved for use. The injection can be performed by anyone with certification in handling radiopharmaceuticals. Imaging is done with standard gamma cameras available in any nuclear medicine department. The addition of the hand-held gamma probe adds a new dimension to application of the technique of lymphatic mapping and identification of areas that retain radiopharmaceuticals. Its use is simple and reproducible. The application of lymphoscintigraphy and gamma-probe localization techniques in clinical medicine is best exemplified with the now commonly used sentinel node approach to staging and treating intermediate-thickness malignant melanoma. A number of other malignant diseases such as breast cancer may have their treatments altered with these techniques as well. As a research and diagnostic tool, the creative application of interstitial lymphoscintigraphy can give important qualitative information regarding the morphology and physiology of the lymphatic system. The development of these techniques for surgical research and practice is reviewed.

Animal model for investigation of spinal cord injury caused by aortic cross-clamping.

The objective of this experimental protocol was to design a large animal model that could simulate the ischemic condition caused by aortic cross-clamping during the operation for intrathoracic and thoraco-abdominal aneurysm. Domestic swine weighing 25 to 30 kg were used for this model. The thoracic cavity was opened through the fourth intercostal space. Cross-clamp was applied below the left subclavian artery. Duration of cross-clamp was 30 min and the reperfusion period was 24 h. Methods of assessment included Tarlov's criteria, histology transmission electron microscopy, and spinal cord perfusion with microspheres. This model is reproducible. The results of experimental protocols completed using this model are referenced. This article discusses the details of the experimental protocol with steps toward reproduction of the model and rationalization. This animal model can be used for the evaluation of the pathophysiology of spinal cord injury and sensory- and motor-evoked potentials, and most importantly it can also be used for the examination of pharmacological interventions for prevention and treatment of ischemia reperfusion injury caused by aortic cross-clamping.