Cuff Technique Research Articles

ORTHOTOPIC LIVER TRANSPLANTATION IN THE MOUSE

Heart and kidney transplantation in the mouse has been well established (1, 2), but orthotopic liver transplantation has not been reported. Although the mouse is one-tenth the size of the rat, there are many advantages to using the mouse for immunologic research. The mouse genome has been more thoroughly characterized than the rat or any other species of mammal. The mouse H-2 system also bears a striking resemblance to the human HLA system. In addition, there are numerous genetically defined inbred strains and wealth of monoclonal antibodies that are commercially available for mouse investigations. A key development in rat orthotopic liver transplantation (3) was the introduction by Zimmerman et al. (4) and Kamada and Caine (5), of the cuff technique instead of suture for some of the venous vascular anastomoses. This method shortened the clamping time of the portal vein and increased survival. We have applied this principle to mouse orthotopic liver transplantation. In our pilot studies, more than 40 syngeneic mouse liver replacements were performed before 6 long-term survivors were obtained. The experience reported here is with the next 48 attempts, in which the surgical success rate was 83%. Male inbred syngeneic mice 10–12 weeks old (25–32 g), from Jackson Laboratory, Bar Harbor, ME, were used as size-matched donors and recipients under methoxyflurane (2.2-dichloro-1,1-difluoroethyl methyl ether) anesthesia. The strains used were B6AF1 (27 pairs), C57BL/6 (11 pairs), and BALB/c (10 pairs). Clean but not sterile operative technique was used, and all procedures were performed under the operating microscope with 4–6.4× magnification.

LEUKOCYTE ADHESION AND CELL DEATH FOLLOWING ORTHOTOPIC LIVER TRANSPLANTATION IN THE RAT

The purpose of these experiments was to employ video microscopy to identify early pathological changes after orthotopic liver transplantation in the rat. Liver transplantation was performed using the cuff technique. Survival was greater than 90% when livers were stored for 1 hr in Ringer's solution prior to transplantation (survival conditions), whereas all rats died following storage of grafts for 4 hr in cold Euro-Collins solution (nonsurvival conditions). Postoperatively, each recipient animal was anesthetized, the abdomen was opened, and the liver was placed on the stage of an inverted fluorescence microscope equipped with a low-light ISIT video camera. Precautions were taken to prevent the liver surface from drying. The fluorescent dyes fluorescein sodium (1.0 mumol/kg), acridine orange (2.5 mumol/kg), and propidium iodide (1 mumol/kg) were injected intravenously to label hepatocytes, polymorphonuclear leukocytes, and the nuclei of irreversibly damaged cells, respectively. In livers from untransplanted rats, movement of labeled leukocytes through the hepatic sinusoids was smooth and rapid (velocity, 500-550 microns/sec) and margination (adhesion) of cells was minimal (less than 1%). After transplantation, however, velocity was diminished 2-3-fold, and margination was increased to 10% of leukocytes in survival groups and to 40% in nonsurvival groups 4 hr postoperatively. In the nonsurvival groups, irreversible cell death detected by propidium iodide fluorescence was minimal 15 min after transplantation--however, massive cell damage was detected 4 hr postoperatively. In addition, serum transaminases and necrosis were higher at 4 hr than 15 min postoperatively. Taken together, these data demonstrate that leukocyte margination increases following orthotopic liver transplantation and is followed rapidly by cell death. These events likely play a role in the mechanism of early graft failure following transplantation.

Effect of Rearterialization on Short-Term Graft Function in Orthotopic Rat Liver Transplantation

The orthotopic liver transplant model in rats has been very useful for immunological studies. However, differing opinions exist as to whether rearterialization of the graft is necessary for such experiments. Therefore, in this study we evaluated the short-term allograft function when rearterialized was compared to restored venous portal flow only and in situ hepatic artery ligation. The technique of orthotopic liver transplantation in the rat with and without rearterialization of the graft is described in detail. In addition, we evaluated the technical feasibility of sutured vascular anastomosis as compared to the traditional cuff technique. Urea synthesis rate was used as a sensitive marker of integrated liver function, including uptake, synthesis and excretion. Standard liver test of bilirubin, plasma aspergine aminotransferase and alanine aminotransferase were measured. We found no significant differences in the biochemical markers between allografts with portal venous flow only compared to the combination with arterial flow. Autopsy was performed after the biochemical studies at day 14. Histopathological analyses revealed no differences between the two groups of transplanted rats. The patency of sutured anastomoses was in our hands found to be superior to that of the cuff technique, with a success rate of more than 90% in rats with portal venous flow. This rat model in which vascular anastomosis is performed with a running suture technique and without rearterialization seems to be excellent for short-term studies of preservation and liver function after orthotopic liver transplantation.

Ammonia elimination as a rapid index of viability in liver grafts in dogs

We examined intraoperative changes in blood ammonia levels and the correlation with graft viability in orthotopic liver transplantation (OLTx) in 29 dogs. Blood ammonia levels following total hepatectomy were examined using five dogs. These levels immediately following hepatectomy (15 min) were significantly higher (212 ± 29 μg/dl) over values noted before hepatectomy (93 ± 11 μg/dl, P < 0.05). OLTx was performed using the cuff technique. The animals were divided into two groups: Group A ( n − 6 pairs), OLTx with a nonpreserved fresh graft; Group B ( n = 6 pairs), OLTx with an 8-hr preserved graft with lactated Ringer (4°C). In both groups, the blood ammonia levels before the surgery and at the anhepatic phase data did not differ; however, following reperfusion, the levels in Group B were significantly higher (211 ± 26 at 15 min, 200 ± 50 μg/dl at 30 min) than those in Group A (121 ± 10 at 15 min; P < 0.01, 109 ± 9 μg/dl at 30 min; P < 0.05). The blood ammonia level highly correlated with adenosine triphosphate contents in the liver tissue, blood level of lactic acid, and amount of bile output, all pertinent indicators of the graft viability. Thus, the potential to eliminate ammonia immediately after reperfusion can serve as an indicator of graft viability. The intraoperative monitoring of blood ammonia levels can be included in management guidelines in cases of liver transplantation.

A nerve cuff technique for selective excitation of peripheral nerve trunk regions

Numerical modeling and experimental testing of a nerve cuff technique for selective stimulation of superficial peripheral nerve trunk regions is presented. Two basic electrode configurations ("snug" cuff monopolar and tripolar longitudinally aligned dots) have been considered. In addition, the feasibility of "steering" excitation into superficial nerve trunk regions using subthreshold levels of current flow from an electrode dot located on the opposite side of the nerve has been tested. Modeling objectives were to solve for the electric field that would be generated within a representative nerve trunk by each electrode configuration; and to use a simple nerve cable model to predict the effectiveness of each configuration in producing localized excitation. In three acute experiments on cat sciatic nerve the objective was to characterize the effectiveness of each electrode configuration in selectively activating only the medial gastrocnemius muscle. Modeling and experimentation both suggest that longitudinally aligned tripolar dot electrodes on the surface of a nerve trunk, and bounded by a layer of insulation (such as a nerve cuff), will restrict excitation to superficial nerve trunk regions more successfully than will monopolar dot electrodes. Excitation "steering" will improve the spatial selectivity of both monopolar and tripolar electrode configurations.

Simplified rat lung transplantation using a cuff technique

A cuff technique is introduced to anastomose pulmonary vein and pulmonary artery in rat lung transplantation. In 11 consecutive cases, the average graft ischemic time was 13.5 +/- 2.0 minutes and operating time 100.7 +/- 4.8 minutes: The time for ischemia was less than one third of previous reports and the time for operation one half of previous reports. Excluding two operative deaths, the survival rate was 88.8% (8/9) on postoperative day 11, when contralateral pneumonectomy revealed excellent graft function supporting the oxygenation of the animals.

A modified technique of orthotopic transplant of the kidney in rabbits.

In this study kidneys were harvested from bred-for-research cats weighing 4 to 5 kg. General principles of donor bilateral nephrectomy en bloc with aorta, vena cava, renal vessels, and ureters were followed. After the harvest the grafts were placed in lactated Ringer slush. A cuff was prepared on the renal vein over a 10 French plastic tube. The aorta was divided and left in connection with the renal artery at each side. Twenty female checkered Flemish giant rabbits weighing 4.0-6.0 kg served as recipients. After premedication with 40 mg/kg of ketamine, anesthesia was maintained with repeated doses (every 10-15 min) of a 0.1-mL mixture of 5 parts ketamine and 1 part acepromazine diluted 50% in a normal saline. Arterial pressure, CVP, blood gases, and temperature were monitored. Through a limited midline incision a native left nephrectomy was performed. The venous anastomosis was performed with a cuff technique without clamping the vena cava (which causes severe hemodynamic instability); the anastomotic time was 2-3 min. The arterial anastomosis was performed with an end-to-side aorta-to-aorta anastomosis; the anastomotic time was 5 to 7 min. There were no episodes of venous or arterial thrombosis. The donor procedure took approximately 40 min, and the backtable preparation of the graft an additional 45 to 60 min. Preparation of the recipient for the anastomosis took 15 min and the anastomotic time (warm ischemia) was 13 +/- 5 min. In this model suitable for xenograft research the duration of the surgery in the recipient has been greatly reduced because of (1) the previous backtable preparation of the graft, and (2) the cuff technique used for venous anastomosis. The present anesthesia regimen and careful hemodynamic monitoring were also important in the success of this model.

Small-bowel transplantation in the rat with a nonsuture cuff technique. Technical and immunological considerations.

Small-bowel transplantation (SBT) using an nonsuture cuff technique was carried out on 137 rats. Preparation of the donor graft was carried out according to conventional procedures. Graft perfusion was done at a fixed pressure of 35 cm water. The left renal vessels of the recipient were dissected, the native kidney removed, and the graft was connected to the vessels by a nonsuture cuff technique. Of the animals, 92% survived for at least 5 days posttransplant. Three different combinations were investigated: (1) isografts; (2) semisyngeneic grafts from nontreated Lewis----(Lewis x DA) F1 hybrids; and (3) semisyngeneic grafts from rabbit antilymphocyte globulin (ALG)-pretreated Lewis----(Lewis x DA) F1. In group 1, 80% of the grafts were unaffected after 1 month; flow studies showed slight or no impairment of circulation in the graft. In group 2, the recipients developed clinical signs of graft-versus-host disease (GVHD) after 1 week, and at the end of the 2nd week the animals showed signs of severe illness, leading to death due to GVHD. There was also a higher percentage of complications in this group. In group 3, 65% of the animals died. However, 27% showed intact grafts and no signs of GVDH after 1 month, indicating that antibody pretreatment of the donor may successfully prevent GVHD SBT.

A four-technique comparative study of orthotopic liver transplantation in the rat

A four-technique controlled study was conducted on rat liver isografting to compare the microsurgical technique (Group 1), the two-cuff technique (Group 2), the three-cuff technique (Group 3), and a newly developed splinting suture technique (Group 4). The 60 day survival rates were significantly better in Groups 2 and 4 than in Groups 1 and 3. The anhepatic phase was significantly shorter with the cuff and splinting techniques than with the microsurgical technique, and total hepatic ischemic time was significantly shorter in the splint group than in the other three groups. Hepatic failure and shock had a higher incidence in those groups displaying a longer total hepatic ischemia time and a longer anhepatic phase. The results of this study show that the two-cuff technique and the splinting technique have substantial advantages over the microsurgical technique and the three-cuff technique. In particular, the splinting technique is preferable to the two-cuff technique because total hepatic ischemia time is shorter, and it is faster for a well-trained microsurgeon to learn this procedure than to learn the cuff technique de novo.

Micro-arterial anastomosis using only two sutures and an autogenous cuff

Microvascular anastomosis using only two sutures and an autogenous cuff was carried out in an experimental model of Wistar albino rats. 40 femoral and 40 epigastric arteries were used for this cuff technique and compared with conventional technique in the same number of vessels. The cuff technique is simple, quick, causes less trauma to the vessel wall and gives a good patency rate. Anastomosis of an artery 0.5mm in diameter is very easy with the cuff technique (98% patency) which remains difficult using conventional technique (0% patency). The disadvantage of this technique may be leakage of blood just after releasing the clamps due to restoration of blood flow, but this is easily controlled within few minutes by mild compression.

Micro-arterial anastomosis using only two sutures and an autogenous cuff.

Microvascular anastomosis using only two sutures and an autogenous cuff was carried out in an experimental model of Wistar albino rats. 40 femoral and 40 epigastric arteries were used for this cuff technique and compared with conventional technique in the same number of vessels. The cuff technique is simple, quick, causes less trauma to the vessel wall and gives a good patency rate. Anastomosis of an artery 0.5mm in diameter is very easy with the cuff technique (98% patency) which remains difficult using conventional technique (0% patency). The disadvantage of this technique may be leakage of blood just after releasing the clamps due to restoration of blood flow, but this is easily controlled within few minutes by mild compression.

Vasoconstrictor response to cold in forestry workers: a prospective study.

In a five year prospective study of the vasoconstrictor response to cold 37 forestry workers were investigated in 1978 and again in 1983. The subjects were classified into three groups: group A (n = 13): no subjective finger symptoms in 1978 and continued sawing until 1983; group B (n = 12): no symptoms in 1978 and stopped sawing before 1983; group C (n = 12): vibration induced white finger (VWF) in 1978. A cold provocation test measuring the finger systolic blood pressure with a cuff and strain gauge technique during combined body cooling and finger cooling to 30 degrees, 15 degrees, and 6 degrees C was applied to all subjects at both investigations. In 1978 all groups had an increased cold response when compared with that of 20 non-exposed controls (p less than 0.05), and the response was more exaggerated in group C than in groups A and B (p less than 0.01). From 1978 to 1983 the vasoconstrictor response increased in group A (p less than 0.05), was in group B (p greater than 0.10), and improved in group C (p less than 0.05). The changes in cold response in groups A and C were significantly larger than the within day variation of the method (p less than 0.01). The aggravation of group A indicates that a further five years use of anti-vibration chain saws induced an increased hyperreactivity in the vasoconstrictor mechanisms but led to subjective symptoms of VWF in only one subject. The improvement in group C was in accordance with the improvements of subjective finger symptoms and was associated with a previous shift from saws without vibration damping devices to anti-vibration saws and with cessation of work. The results of group C indicate that VWF may improve or subjectively disappear if exposure to vibration is reduced or stopped. The cold provocation test was more sensitive than the Taylor-Pelmear stage assessments (p<0.05). The test may be of guidance in evaluation preventive measures.

Small-bowel transplantation in the rat with a nonsuture cuff technique: Technical and immunological considerations

Abstract. Small-bowel transplantation (SBT) using an nonsuture cuff technique was carried out on 137 rats. Preparation of the donor graft was carried out according to conventional procedures. Graft perfusion was done at a fixed pressure of 35 cm water. The left renal vessels of the recipient were dissected, the native kidney removed, and the graft was connected to the vessels by a nonsuture cuff technique. Of the animals, 92% survived for at least 5 days posttransplant. Three different combinations were investigated: (1) isografts; (2) semisyngeneic grafts from nontreated Lewis(LewisDA) Fl hybrids; and (3) semisyngeneic grafts from rabbit antilymphocyte globulin (ALG)-pretreated Lewis(LewisDA) Fl. In group 1, 80% of the grafts were unaffected after 1 month; flow studies showed slight or no impairment of circulation in the graft. In group 2, the recipients developed clinical signs of graft-versus-host disease (GVHD) after 1 week, and at the end of the 2nd week the animals showed signs of severe illness, leading to death due to GVHD. There was also a higher percentage of complications in this group. In group 3, 65% of the animals died. However, 27% showed intact grafts and no signs of GVDH after 1 month, indicating that antibody pretreatment of the donor may successfully prevent GVHD SBT.

Monitoring the occurrence and duration of electroconvulsive fits.

During 100 routine psychiatric hospital electroconvulsive treatments the medical staff administering treatment experienced little difficulty in deciding that a fit had occurred. The judgement was based on simple clinical observation of a succession of clonic bodily movements, and high inter-rater agreement was found for the measurement of fit duration. The cuff technique was also used, but it tended to underestimate fit duration and is not recommended for routine ECT practice.

Electrodermal response as a monitor in electroconvulsive therapy.

A study comparing the use of electrodermal response with the cuff technique and clinical judgment as monitors in electroconvulsive therapy is reported. A sensitivity of 90.5% and a specificity of 41.7% were found and it is, therefore, suggested that this method is not used routinely.

Application of the medical anti-shock trouser (MAST) increases cardiac output and tissue perfusion in simulated, mild hypovolaemia.

We have studied the haemodynamic effects of the application of the medical anti-shock trouser (MAST) in 10 healthy subjects in the semi-upright position in order to simulate mild hypovolaemia. Left ventricular end diastolic dimension (EDD) was measured by M-mode echocardiography and cardiac output (CO) by the Doppler ultrasound technique. Forearm blood flow (FBF) was measured by plethysmography and blood pressure (BP) by the standard cuff technique. Systematic increases in MAST pressure of up to 80 mm Hg were applied. EDD increased to a maximum of 9.3% (p less than or equal to 0.01) which was associated with a maximum increase in CO of 31.7% (p less than or equal to 0.05). FBF increased by a maximum of 54.2% (p less than or equal to 0.001) whilst BP increased by a maximum of 12% (p less than or equal to 0.001). These results demonstrate that the application of the MAST is an effective means of transferring blood to the central circulation by compression of the capacitance vessels resulting in significant increases in cardiac output and tissue perfusion. At high pressures there was evidence of compression of resistance vessels, which may be useful in reducing blood loss. The ease and rapidity with which his suit can be applied suggests that it may be useful in the short term treatment of hypovolaemia.

Axons regenerated through silicone tube splices: I. Conduction properties

Changes in conduction properties of axons regenerating across a 10-mm gap bridged by a silicone cuff were investigated from compound action potential responses. Compound action potentials were detected as early as 6 weeks after surgery, and were small and slowly conducted at maximum velocities of about 3 m/s. With longer regeneration time, the potentials increased in size, velocity, and complexity. Conduction velocities increased rapidly at first then slowly and asymptotically approached rates that were approximately 40% below normal after 10 months. One component of the compound action potential, the refractory period, decreased from 5 ms to near normal value after only 3 months. The time constant of excitation changed more rapidly, and after 2 months approximated values near those for controls. The properties of axons regenerated through silicone tube splices were comparable to those observed in axons regenerating across an epineural suture with no gaps. The database for the time course of events established here will be useful in guiding studies using the silicone cuff technique as an in situ experimental chamber for studies of regeneration and remyelination.

Effect of prolactin on blood pressure and cardiovascular responsiveness in the rat.

The effects of chronic ovine PRL (oPRL) infusion on resting systolic blood pressure (BP), heart rate, and pressor responsiveness to acute administration of norepinephrine and angiotensin were studied in adult male Sprague-Dawley rats. oPRL was administered over 7 days, via osmotic pump implanted ip on Day 1, at rates of 0, 0.15, 0.30, 0.60, 1.20, and 4.80 micrograms/hr. Resting BP and heart rate were indirectly determined in conscious rats by tail cuff technique on Days 1, 4, and 7 following pump implantation. In addition, acute pressor responses to ia norepinephrine (4.3 micrograms) and angiotensin (1.25 micrograms) were directly measured via arterial cannula in halothane-anesthetized rats on Day 7 of oPRL administration. oPRL infusion did not alter resting BP or heart rate over the 7 days. However, oPRL increased the BP response to norepinephrine at infusion rates of 0.60 and 4.80 micrograms/hr (P less than 0.01 vs controls). Body weight increases during the study were also greater in groups receiving 0.15, 0.30, 0.60, and 4.80 micrograms oPRL/hr (P less than 0.05) than those in control animals. oPRL decreased pressor responses to angiotensin at infusion rates of 0.30 and 1.20 micrograms/hr (P less than 0.01). These data suggest that, although the vascular effects of oPRL may not be evident under resting conditions, oPRL enhances vascular reactivity to norepinephrine infusion and depresses vascular reactivity to angiotensin infusion. Furthermore, at oPRL infusion rates which affect pressor responses to norepinephrine, oPRL increases body weight gain. These findings support a role for PRL in cardiovascular regulation during conditions of altered sympathetic activity.

Points: Ethics and politics

Tracheostomy tubes are used to administer positive-pressure ventilation, to provide a patent airway, and to provide access to the lower respiratory tract for airway clearance. They are available in a variety of sizes and styles from several manufacturers. The dimensions of tracheostomy tubes are given by their inner diameter, outer diameter, length, and curvature. Differences in dimensions between tubes with the same inner diameter from different manufacturers are not commonly appreciated but may have important clinical implications. Tracheostomy tubes can be cuffed or uncuffed and may be fenestrated. Some tracheostomy tubes are designed with an inner cannula. It is important for clinicians caring for patients with a tracheostomy tube to appreciate the nuances of various tracheostomy tube designs and to select a tube that appropriately fits the patient. The optimal frequency of changing a chronic tracheostomy tube is controversial. Specialized teams may be useful in managing patients with a tracheostomy. Speech can be facilitated with a speaking valve in patients with a tracheostomy tube who are breathing spontaneously. In mechanically ventilated patients with a tracheostomy, a talking tracheostomy tube, a deflated cuff technique with a speaking valve, or a deflated cuff technique without a speaking valve can be used to facilitate speech.

Gamma linolenic acid attenuates cardiovascular responses to stress in borderline hypertensive rats.

The purpose of the present study was to investigate the effects of gamma linolenic acid (GLA) on cardiovascular responses to psychosocial stress (isolation) and to pressor hormones in the genetically borderline hypertensive rat (SHR X WKY). Adult male SHR X WKY were divided into two groups following five weeks of group housing. One group (GLA) received eight weeks constant flow osmotic pumps releasing 0.04 mg GLA in olive oil/kg-hr, while the second group received dummy pumps (DUM). One week following pump implantation, each group was divided into two subgroups and exposed to a four-week experimental period of either continued group housing (no stress) or isolation (stress). A two-week recovery period of group housing followed the experimental period. Blood pressure and heart rate were determined weekly by the tail cuff technique. At the end of the recovery period, animals in the no stress condition were anesthetized and received an arterial cannula for NOR and ANG infusion and direct BP recording. Then the responses to an ED50 of NOR and ANG were determined. All animals were then killed for determination of heart weight and adrenal weight. All groups had mean control period systolic BP values ranging from 143-146 mm Hg. In the no stress condition, neither GLA nor DUM altered BP over the course of the study. However, BP increased in the DUM group during all four weeks of the isolation period vs the control period (p less than 0.01), whereas BP increased only in week 1 in the GLA group (p less than 0.05). Heart rate increased during stress in the DUM group (p less than 0.05), but not in the GLA group. Vascular reactivity to NOR was unaffected by GLA administration.(ABSTRACT TRUNCATED AT 250 WORDS)