Transport of viral-size particulate matter after intravenous versus intralymphatic entry.

OBJECTIVE: Investigation of the transport of viral-size particles after intravenous versus intralymphatic injection and the functional validity of lymphatico-venous communications. METHODS: In the canine model, [99mTc] sulfur colloid particles (100-200 nm) were injected into either the principal vein or into the main lymphatic channel exposed at the paw. Samples of blood and lymph were collected at the groin from the cannulated femoral vein and from a major lymphatic vessel. Parameters including particle arrival time, concentration, flux, and accumulation were determined for a 45-minute period using gamma counting. RESULTS: After intralymphatic injection, particles arrived in the venous blood in an average of 4 seconds. The mean arrival time of particles in the lymph after intravenous injection was 25.4 +/- 6.44 minutes. Intralymphatic injection increased lymph flow and enhanced particle transport. Concentration values in the venous blood after intralymphatic injection and in lymph after intravenous injection were comparable. Flux values depended primarily on flow conditions. Particle accumulation in the lymph after intravenous injection was delayed, but continued to increase throughout the experiment. CONCLUSIONS: There are functional lymphatico-venous communications at the very peripheral level under physiological conditions, which allow rapid transport of viral-size particulate matter between the two pathways and may contribute to the spread of viral infection.

Inhibition of needlestick-induced simulated viremia by local measures.

BACKGROUND: The possibility of confinement of simulated retrovirus to the inoculation site after needlestick injuries to enhance chances of local intervention and function of lymphaticovenous communications was investigated. METHODS: Using the canine model, technetium-99 m sulfur colloid particles were injected subcutaneously and into the vein and lymphatics. Blood and lymph were collected at a higher level from the femoral vein and the major lymphatic. Flow rates, particle arrival times, concentrations, and other variables were evaluated for 45 minutes by gamma counting. A tourniquet was used to slow dissemination after subcutaneous injection. RESULTS: After subcutaneous inoculation, particles arrived in the blood at 2.81 +/- 0.54 minutes and in the lymph at 6.0 +/- 1.47 minutes. Application of a tourniquet delayed appearance in the blood to 7.11 +/- 1.5 minutes and in the lymph to 40.0 +/- 5.1 minutes. Concentration of particles in lymph was 1,000 times higher than in the blood. Flux values were comparable in both pathways, but accumulation patterns were different. After intravenous injection, particles arrived in lymph at 25.4 +/- 6.44 minutes. After intralymphatic injection particles arrived in the blood within 4 seconds. CONCLUSIONS: There are functional lymphaticovenous communications at the peripheral level. The period between virus inoculation and blood and lymph invasion may be extended by application of a tourniquet; therefore, time could be gained for local intervention.

Propagation of viral-size particles in lymph and blood after subcutaneous inoculation.

OBJECTIVE: We investigated the propagation of viral-size particles by lymph and blood after subcutaneous injection. METHODS: In the canine model, transport of [99mTc] sulfur colloid particles of different sizes was studied in different settings in venous blood and lymph for 45 minutes after inoculation. RESULTS: The mean arrival time of particles in the blood was 2.10+/-0.46 minutes and 8.87+/-1.72 minutes in the lymph. Lymph flow in the canine leg was 28.79 +/-2.09) microl/min and was increased by leg massage. The particle concentration was 1000 times higher in the lymph fluid than in blood. Particle flux values were comparable in blood and lymph. The accumulation of particles in blood initially rose faster than in lymph. Accumulation in lymph rises slower but continues longer and reaches higher values. Ninety percent of the inoculum remains at the injection site for at least 45 minutes. Particle size matters more in blood distribution. Leg massage enhances particle transport by lymph. CONCLUSIONS: After subcutaneous injection, viral-size particles initially arrive in the blood and later in the lymph. Accumulation in lymph and blood increases for a prolonged time after inoculation. Results suggest possibilities for limiting the spread of infectious matter by early local antiviral treatment.

Apoptosis is initiated by myocardial ischemia and executed during reperfusion.

Ischemia/reperfusion leading to myocyte cell death has been reported as either necrotic or apoptotic or a combination of both. The importance of necrosis is well established but the role of apoptosis and the time of initiation are still unknown. Normothermic global ischemia of either 45 or 90 min duration followed by 6 h of reperfusion were induced in isolated canine hearts. After 45 min of ischemia, left ventricular function and adenine nucleotide (AN) content had recovered during reperfusion indicating reversible injury. DNA fragmentation determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) was absent as was the 85 kDa fragment of poly-(ADP-ribose) polymerase (PARP). After 90 min of ischemia, electron microscopy indicated necrotic cell death in 90% of myocytes. Recovery of function and AN content during reperfusion was minimal. At the end of ischemia, caspase-3 was activated in 30% of all myocytes and PARP 85 kDa fragments were present by Western blot, indicating initiation of the apoptotic cascade. Lamin-B(1)labeling was significantly reduced from 90% in myocytes in control and ischemia to 30% in early reperfusion. Completion of apoptosis seen by TUNEL was evident in late reperfusion (7.6% of myocytes and 8.3% of non-myocytes). Experiments with 6 h ischemia without reperfusion showed absence of DNA fragmentation. We conclude that apoptotic cell death is initiated by ischemia but that reperfusion is needed for completion of the apoptotic cascade. Furthermore, it is concluded that cell death in acute global ischemia followed by reperfusion occurs predominantly by necrosis and that apoptosis is of minor importance in this pathophysiological situation.

Accidental injuries by HIV-contaminated instruments in health provider or research environments: can seroconversion be prevented?

The rate of seroconversion from percutaneous needlestick exposure to HIV infection is approximately 0.3 per cent. To investigate the possibility of local confinement of HIV, 100 to 200 nm Tc-99m sulfur colloid particles were injected in the canine model subcutaneously at the knee level and collected proximally at the groin from the cannulated femoral vein and lymphatic channel. Tourniquet compression (250 mm Hg) was used as an intervention to possibly restrict particle spread. It was found that particles arrived in the blood at 2.81 +/- 0.54 minutes, with later arrival in the lymph at 6.0 +/- 1.47 minutes. Tourniquet application delayed the appearance of the particulate matter in the blood up to 7.11 +/- 1.5 minutes and in lymph up to 40.0 +/- 5.10 minutes. The concentration of radioactivity in the lymph was higher than in the venous blood. The distribution of the particles reflected by flux was comparable in both pathways. The accumulation curves did not reach plateaus during 45 minutes in lymph and 15 minutes in blood. Radioactive scanning revealed that about 90 per cent of the injected particles remained locally with gradual release for at least 45 minutes. Our results suggest that HIV, introduced by needlestick injury, can be contained for possible viricidal treatment if the response includes rapid immobilization and tourniquet of the area.

Extending myocardial viability during heart preservation with cyclosporine A.

BACKGROUND AND AIM OF STUDY: Hypothermic preservation (PRES) of donor hearts is limited to 12-14 hours for complete functional recovery after reperfusion. In a canine heterotopic heart transplant model, 50% to 60% functional recovery returned after 18 hours of PRES with University of Wisconsin (UW) solution. Concomitant with functional changes were marked increases in apoptotic cells at 2 (2.69%) and 6 (5.98%) hours of reperfusion with a concomitant decrease in lamin B1 (2% and 7.6%, respectively) with no evidence of necrotic cells. These results suggested that blockade of apoptosis may prolong myocardial viability during PRES and reperfusion. METHODS: Donor hearts were subjected to 18 and 24 hours of PRES (2 degrees C to 4 degrees C) with and without cyclosporine A (CyS) treatment (apoptosis blocker). CyS was given to the donor animal (10 mg/kg), in the PRES solution (10(-5) mol/L), slowly infused during the PRES period (1 mL/min), and also to the recipient animal (2.5 mg/kg). RESULTS: After 18 hours of PRES with CyS, function returned to 100% within 1 hour and stayed at this level throughout a 6-hour recovery period. Apoptotic myocytes were reduced (55%) after 18 hours PRES with CyS treatment, and 6-hour reperfusion lamin B1 was reduced to only 3.7%. Twenty-four hour PRES in UW resulted in no functional recovery. However, after CyS treatment, functional recovery returned to 100% after 4 hours of reperfusion. Adenosine triphosphate (ATP) and creatine phosphate (CP) concentrations were surprisingly the same with or without CyS treatment at 18 hours and lower with 24 hours. CONCLUSIONS: Use of CyS in the PRES solution prolongs myocardial viability during donor heart PRES. The mechanism of action may be associated with the mitochondrial permeability transition (MPT) pore via cyclophilin D binding.

Transport of colloidal particles in lymphatics and vasculature after subcutaneous injection.

This study was designed to determine the transport of subcutaneously injected viral-size colloid particles into the lymph and the vascular system in the hind leg of the dog. Transport of two colloid particles, with average size approximately 1 and 0.41 microm, respectively, and with and without leg rotation, was tested. Leg rotation serves to enhance the lymph flow rates. The right femoral vein, lymph vessel, and left femoral artery were cannulated while the animal was under anesthesia, and samples were collected at regular intervals after subcutaneous injection of the particles at the right knee level. The number of particles in the samples were counted under fluorescence microscopy by using a hemocytometer. With and without leg rotation, both particle sets were rapidly taken up into the venous blood and into the lymph fluid. The number of particles carried away from the injection site within the first 5 min was <5% of the injected pool. Particles were also seen in arterial blood samples; this suggests reflow and a prolonged residence time in the blood. These results show that particles the size of viruses are rapidly taken up into the lymphatics and blood vessels after subcutaneous deposition.

Comparison of intermittent warm and cold blood perfusion during hypothermic myocardial preservation on functional and metabolic recovery.

Numerous techniques are used to maintain intraoperative heart viability. The studies presented here evaluated heart function and metabolism after various periods of preservation up to 4 hours with intermittent warm and cold blood perfusion. Using a heterotopic heart model cooled to 10 degrees C and maintained for 1, 2, 3, and 4 hours, various preservation techniques were compared. Changes in myocardial metabolism were determined from substrate uptakes and biopsy samples of the left ventricular muscle for high-energy phosphates. Preservation techniques included: (1) sustained hypothermia, (2) 1 or 2 hours of sustained warm blood perfusion with fibrillation, (3) intermittent cold blood perfusion during 2, 3, and 4 hours of preservation, (4) intermittent warm blood perfusion during 2, 3, and 4 hours of preservation and (5) a control group (no preservation). Normothermic fibrillation had no effect on postpreservation functional or metabolic parameters. Sustained hypothermia reduced functional recovery proportional to the length of ischemia. The cold intermittent procedures maintained function and metabolism better than sustained hypothermia, while warm intermittent preservation maintained function and metabolism at control levels throughout the recovery period for all preservation techniques. Changes in ATP mirrored the functional changes. Creatine phosphate (CP) was markedly reduced during heart isolation and preservation and exceeded the control by 100% during reperfusion. For operative procedures of 2 hours or less, functional and metabolic recovery was not affected by the various preservation methods applied. Warm intermittent perfusion during hypothermic preservation offered the best protection for the myocardium. The warming cycles during hypothermia may provide some degree of preconditioning and protect the myocardium during reperfusion.

Cardiomyocyte apoptosis in acute and chronic conditions.

Myocytes can die by necrosis or by apoptosis and the characteristics of both kinds of cell death are so typical that a differentiation can be made by histological and molecular-biological methods using electron microscopy, dUTP labeling with fluorescence or peroxidase staining (TUNEL) and the DNA laddering method. However, the problem of quantification of apoptotic cells has not been completely solved because of lack of standardization as well as uncritical use and interpretation of the TUNEL method. Equally, quantification of apoptotic cells is not optimal until now because of three reasons: methodological (overinterpretation of results, no differentiation between myocytes and non-myocytes), experimental (global or regional acute ischemia, chronic conditions such as heart failure or hibernating myocardium), and interpretation (unknown time period for the completion of apoptosis). This problem is reflected in the large differences in incidence of apoptosis reported. Our own data show that in dog myocardium made globally ischemic for 90 min, 8% of the myocytes showed a positive staining for apoptosis (TUNEL method) after 6 h of reperfusion. Despite these results the question of reperfusion injury and the influence of apoptosis still remains open, because it can not be excluded until now that the apoptotic process is initiated during the ischemic period. Studies in hibernating myocardium and chronic heart failure show a similar situation, because of a wide variation of numbers of apoptotic cells and the limited possibility to investigate human tissue. There is no doubt that apoptosis plays an important role in chronic pathophysiological situations such as heart failure and hibernating myocardium but the importance of apoptosis in the acute situation of ischemia/reperfusion still has to be clarified.

Ischemia affects cardiac proteins in healthy animals less severely than in human patients.

BACKGROUND: Recently, our group showed that in human hearts proteins are extremely sensitive to ischemic injury. The purpose of this investigation was to evaluate the effects of ischemia on contractile and cytoskeletal proteins in rabbit and pig hearts and to compare these findings with those obtained in humans. METHODS: Rabbit hearts were arrested by perfusion with Euro-Collins solution at different temperatures. Hearts perfused with buffer served as controls. Tissue samples were incubated for varying time intervals and processed for immunohistochemistry and electron microscopy. Porcine hearts were treated in the same manner. Changes in the localization of myosin, desmin, and tropomyosin antibodies were evaluated and the degree of ischemic injury was determined by electron microscopy. RESULTS: Healthy animal hearts tolerate ischemia better than human hearts. Cardiac proteins are more sensitive to ischemia than the ultrastructural cellular organelles. Temperatures as low as 0 degree C produce more cell damage than 4 degrees C and should therefore be avoided. The Euro-Collins solution protects the myocardium better than buffer. CONCLUSIONS: We conclude that healthy animal hearts are more resistant to ischemia than diseased human hearts and that results from experimental studies should be interpreted with caution with regard to the human situation.

Effects of canine donor heart preservation temperature on posttransplant left ventricular function and myocardial metabolism.

The generally accepted method of preserving donor heart integrity during transfer is to arrest it with cold cardioplegic solution, then store it in a plastic bag immersed in an iced electrolyte solution. Temperatures between 0 degree C and 4 degrees C are maintained by this method until the heart is transplanted. Although profound hyperthermia best inhibits metabolic processes, it may damage the myocardium. Higher myocardial temperatures may be more advantageous and may result in better preservation. The efficacy of this hypothesis has been investigated in a canine model. The hearts of 40 dogs were isolated, arrested with cold cardioplegia, removed from the animal, and stored at different temperature ranges from 0-3 degree C to 12-15 degrees C for 4 hr. After this time period, the hearts were transplanted into a recipient animal in the cervical heterotopic position. The degree and speed of myocardial functional recovery were monitored by measuring end-systolic elastance generated from pressure-diameter loops using sonomicrometry techniques. Myocardial metabolism was studied simultaneously by monitoring coronary flow, O2, glucose, lactate, pyruvate, and free fatty acid uptakes. The results were compared with those from a control group of hearts transplanted immediately after their removal. Our results indicate that donor heart function was significantly depressed 30 min after heterotopic transplantation, but returned to "control" levels after 2 hr when stored between 0 degrees C and 6 degrees C. Myocardial function remained significantly depressed throughout the 2-hr recovery period in hearts stored at higher (6-15 degrees C) temperatures. Hearts stored at all temperatures continued to extract glucose, lactate, and free fatty acids, but produced significantly higher levels of pyruvate at higher storage temperatures, which may be related to the favored use of free fatty acids. In conclusion, donor hearts stored at colder temperatures for 4 hr regain complete left ventricular function faster than hearts stored at higher temperatures. Our experiments support the presently applied methods of donor heart preservation for 4 hr.

Bench coronary cineangiography. A possible way to increase the number of hearts available for transplantation.

The method of "bench coronary cineangiography," that is, ex vivo contrast examination of the donor heart before implantation, is presented. The procedure appears to be most effective in detecting pathologic changes in the coronary arterial system of the explanted heart and thus would allow substantial extension of the age limits of donor hearts that may be acceptable for transplantation.

Prevention of retrovirus infection after injury with contaminated instruments: an experimental study.

Owing to similarities between human immunodeficiency virus and feline retroviruses, the feline model was chosen for the study to investigate the efficacy of timely topical treatment of accidental human immunodeficiency virus infection in the operating room. Cats were subcutaneously inoculated with either feline leukemia virus or feline immunodeficiency virus. An effort was made to neutralize the virus in loco either by infiltration of the inoculation site with povidone-iodine or with monoclonal antibodies, or by cauterization and excision. The animals were periodically monitored for feline leukemia virus antigens or for feline immunodeficiency virus antibodies. The results indicated that in the feline model, the development of generalized virus infection may be prevented by local measures if applied immediately.

Enhancing the applicability and effectiveness of intraaortic balloon counterpulsation.

Severe maneuvers designed to enhance the applicability and effectiveness of intraaortic balloon pulsation are presented. (1) Insertion of balloon catheter directly into the ascending aorta. The technique uses an indwelling silastic snare that allows direct insertion of a balloon catheter into the ascending aorta in the course of open heart operations without the necessity of returning the patient to the operating room and reopening the chest at the time of balloon catheter removal. (2) Elimination of electric artifacts in the course of intraaortic balloon assist. A method is presented that utilizes optical rather than electric signals to operate the intraaortic balloon pump and eliminates pacer interference as well as other electrical artifacts. (3) Enhancing assist effectiveness by balloon positioning. In a series of clinical observations, it was found that the effectiveness of balloon assist may be enhanced by as much as 75% by appropriate positioning. The previously held concept that placing the balloon in a subclavian location is optimal is challenged and it is recommended that the proper position of the balloon catheter be determined by using appropriate hemodynamic measurements in different locations. (4) Control of bleeding following removal of percutaneously inserted transfemoral balloon catheter. The technique utilizes a balloon catheter which is introduced into the puncture hole of the femoral artery after minimal surgical dissection and allows direct suturing of the bleeding source.

Can AIDS be prevented after injury with contaminated instruments?

Particulate matter comparable in size with that of human immunodeficiency virus was subcutaneously injected into experimental animals. Such matter remained at the inoculation site long enough to suggest the possibility that human immunodeficiency virus can be destroyed in loco before it invades the host's circulation. These findings may be useful in developing a method to prevent acquired immunodeficiency syndrome after accidental injury with human immunodeficiency virus-contaminated instruments.

Rapidly growing nontuberculous mycobacteria: a new enemy of the cardiac surgeon.

A review of atypical mycobacterial infections complicating cardiac operations is presented. Proven sources of infections at different institutions include contaminated porcine valves and municipal water supply, but the mode of transmission in the great majority of patients remains unclear. There are two principal clinical forms of atypical mycobacterial infections after cardiac operations--endocarditis and sternal osteomyelitis. The latter has characteristics resembling tuberculotic "cold abscess." Specialized laboratory testing is necessary to confirm the diagnosis, and surgeons may have to take the initiative to request special microbiological investigation in cases where infection is clinically suspected but routine cultures are reported as "negative." The prognosis for patients who have any atypical mycobacterial infection after a heart operation is severe. Those infected with the strain chelonei and those whose cardiac chambers were entered during operation fare worse. This dim clinical prognosis may be improved by appropriate and aggressive antibiotic and surgical therapy. Awareness of the urgency of special bacteriological studies is the key to successful management.

Inherent dangers of simultaneous application of microfibrillar collagen hemostat and blood-saving devices.

Microfibrillar collagen hemostat is a topically applicable hemostatic agent that has been introduced relatively recently. Because of the possibility that this substance may pass through different blood-collecting circuits and cause organ damage if reintroduced into the patient's circulation, we performed a series of in vitro and in vivo experiments. The results of these experiments suggest that such a passage may indeed occur and could cause organ damage, either by direct or by induced embolization that cannot be completely prevented even with the application of commercially used filters. We therefore recommend that the substance should not be used if the shed blood is intended to be collected and returned into the patient's circulation.

An autoperfused heart-lung-preparation: metabolism and function.

The number of heart transplantations performed in the United States is increasing, and better preservation techniques are needed for distant transport and improved organ viability. Earlier experiments demonstrated that the autoperfused heart-lung preparation maintains adequate function for six to seven hours without exogenous substrates or medications. The present study evaluated the metabolic alterations at normothermia in an autoperfused heart-lung preparation and if its longevity can be extended by satisfying metabolic requirements. Thirty autoperfused heart-lung preservations were tested with an elevated buffer-bag that maintained left ventricle pressure between 75 mm Hg and 80 mm Hg. The entry and exit ports of the buffer-bag were fitted with one-way valves to insure blood circulation. Left ventricle and arterial pressure, blood pH, PCO2, PO2, glucose, free fatty acids, pyruvate and lactate were measured at regular intervals. In a first series of experiments, myocardial biopsies were taken for ATP determinations. The autoperfused heart-lung preparations were found to consume preferentially free fatty acids until their arterial level dropped to 350 +/- 24 microEq/L. Glucose then became the perferred substrate. After six to seven hours, when the glucose level dropped to 10 mg/dL, the cardiac activity stopped. In a second series, a 10% glucose solution containing 25 IU/dL of insulin was infused at a rate of 0.1 mL/min, extending the longevity of the preparation up to 18 hours. Then, the heart dilated and abruptly stopped. Massive bacterial contamination was found. When aseptic techniques were used in conjunction with antibiotics, the longevity was extended to 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

The value of thermography in the early diagnosis of postoperative sternal wound infections.

Peristernal skin temperatures were recorded postoperatively by infrared thermography in 150 patients. Persistent elevation of peristernal skin temperature during the 3rd and 4th post-operative week was found in 5 patients, all of whom developed sternal wound infection. A further group of 18 patients, all suspected to have occult wound infection, showed persistent temperature elevation in 7 patients, 6 of these patients were proven later to have manifest infection and needed treatment. Close thermographic scruting of the incision in patients with suspected but not proven infection appears to be useful in deleting early stages of deep seated infections.