Immersion Hypothermia Research Articles

The Ang-(1-7)/MasR axis ameliorates neuroinflammation in hypothermic traumatic brain injury in mice by modulating phenotypic transformation of microglia.

The Ang-(1-7)/MasR axis is critically involved in treating several diseases; For example, Ang-(1-7) improves inflammatory response and neurological function after traumatic brain injury and inhibits post-inflammatory hypothermia. However, its function in traumatic brain injury (TBI) combined with seawater immersion hypothermia remains unclear. Here, we used a mice model of hypothermic TBI and a BV2 cell model of hypothermic inflammation to investigate whether the Ang-(1-7)/MasR axis is involved in ameliorating hypothermic TBI. Quantitative reverse transcription PCR, western blotting assay, and immunofluorescence assay were performed to confirm microglia polarization and cytokine regulation. Hematoxylin-eosin staining, Nissl staining, and immunohistochemical assay were conducted to assess the extent of hypothermic TBI-induced damage and the ameliorative effect of Ang-(1-7) in mice. An open field experiment and neurological function scoring with two approaches were used to assess the degree of recovery and prognosis in mice. After hypothermic TBI establishment in BV2 cells, the Ang-(1-7)/MasR axis induced phenotypic transformation of microglia from M1 to M2, inhibited IL-6 and IL-1β release, and upregulated IL-4 and IL-10 levels. After hypothermic TBI development in mice, intraperitoneally administered Ang-(1-7) attenuated histological damage and promoted neurological recovery. These findings suggest that hypothermia exacerbates TBI-induced damage and that the Ang-(1-7)/MasR axis can ameliorate hypothermic TBI and directly affect prognosis.

Immersion hypothermia activates proteolitic reactions in rat tissues

Immersion hypothermia activates proteolitic reactions in rat tissues

Functional recovery after accidental deep hypothermic cardiac arrest: Comparison of different cardiopulmonary bypass rewarming strategies.

Introduction: Using a porcine model of accidental immersion hypothermia and hypothermic cardiac arrest (HCA), the aim of the present study was to compare effects of different rewarming strategies on CPB on need for vascular fluid supply, level of cardiac restitution, and cerebral metabolism and pressures. Materials and Methods: Totally sixteen healthy, anesthetized castrated male pigs were immersion cooled to 20°C to induce HCA, maintained for 75 min and then randomized into two groups: 1) animals receiving CPB rewarming to 30°C followed by immersion rewarming to 36°C (CPB30, n = 8), or 2) animals receiving CPB rewarming to 36°C (CPB36, n = 8). Measurements of cerebral metabolism were collected using a microdialysis catheter. After rewarming to 36°C, surviving animals in both groups were further warmed by immersion to 38°C and observed for 2 h. Results: Survival rate at 2 h after rewarming was 5 out of 8 animals in the CPB30 group, and 8 out of 8 in the CPB36 group. All surviving animals displayed significant acute cardiac dysfunction irrespective of rewarming method. Differences between groups in CPB exposure time or rewarming rate created no differences in need for vascular volume supply, in variables of cerebral metabolism, or in cerebral pressures and blood flow. Conclusion: As 3 out of 8 animals did not survive weaning from CPB at 30°C, early weaning gave no advantages over weaning at 36°C. Further, in surviving animals, the results showed no differences between groups in the need for vascular volume replacement, nor any differences in cerebral blood flow or pressures. Most prominent, after weaning from CPB, was the existence of acute cardiac failure which was responsible for the inability to create an adequate perfusion irrespective of rewarming strategy.

Стимулювання системи протеїназа-інгібітор протеїназ у результаті імерсійної гіпотермії

The effect of immersion hypothermia (IН) on proteolysis activity in adult male rats, which was performed at 0 °C for 5 min in the “forced swimming” test, studied; the body temperature decreased to 27.5 ± 0.5°C. In blood serum and non-nuclear fractions of homogenates of cerebral cortex, hypothalamus, cerebellum, brainstem, lungs, heart, liver and kidneys tissues were determined the total proteinase activity (TPA), non-trypsin-like proteinases (NTPs), such as chymase, prostate-specific antigen, partially tonin, kallikrein rK9, as well as trypsin-inhibitory activity of α-1-proteinase inhibitor (α-1-PI), α-2-macroglobulin (α-2-MG) by highly sensitive (10-9–10-10 g) enzymatic methods. It is noted that IH led to the TPA increase in all studied tissues (4-84 times), which corresponds to the psycho-emotional effects and the phenomenon of hormesis. After 24 h, TPA decreased, remaining above the control level, and in the kidneys increased further (90 times). NTLP activity as a result of IH increased in blood serum and cerebellum, decreased in the hypothalamus, and after 24 h increased further in serum (7 times), cerebellum, and heart. The activity of α-1-PI also increased in the brainstem, lungs, heart and kidneys, and decreased after 24 h in serum below the control level, and in the brainstem remained high, protecting against proteolytic attack. The activity of α-2-MG increased in the hypothalamus, heart, and cerebral cortex, maximum in the brainstem (2-5 times), and after 24 h - more significantly (24 times), but there were no changes in the cerebellum, where its initial level is the biggest. Thus, the development of IG as a result of swimming in cold water for 5 min at 0oC has a stimulating effect on the body and leads to a significant activation of the reactions of limited proteolysis.

Water Rewarming After Seawater Hypothermia Mitigates IL-1β in Both Intestinal Tissue and Blood.

In this study, the rat models of severe hypothermia induced by seawater immersion were established in artificial seawater immersion at 15°C for 5 hours. With the rewarming measurement of 37°C water bath, the rewarming effects were evaluated by monitoring basic vital signs and dynamically detecting intestinal inflammation cytokines. Fifty Sprague-Dawley rats were randomly divided into five groups including the control group (group C), hypothermia group (group H), 2-hour rewarming group (group R2), 6-hour rewarming group (group R6), and 12-hour rewarming group (group R12), with 10 in each group. The basic vital signs of rats (i.e., core temperature, respiration, heart rate, and muscle tremor) were constantly recorded. The inflammatory factors were detected in the intestinal tissue via a protein chip GSR-CAA-67 of Innopsys, and the verification by reverse transcription-quantitative polymerase chain reaction. The levels of cytokines (interleukin IL-1β, IL-6, and IL-10) were detected from blood samples collected at the end of the observation period via enzyme-linked immunosorbent assay. The expression landscape of IL-1β in the intestinal tissue was validated by immunohistochemistry. Five hours of immersion in artificial seawater at 15°C successfully induced severe hypothermia of rats. After 2 hours of constant water bath rewarming at 37°C, the basic vital signs recovered to the normal level and maintained stably as well as the acute inflammatory reaction alleviated effectively, which indicated that 37°C of water immersion rewarming had the potential to be a suitable method for early treatment of water immersion hypothermia. After the process of hypothermia, several inflammatory cytokines of rats in rewarming groups changed distinctly with IL-1β, showing the most significant variations compared with group C, which confirmed IL-1β as a potential monitoring biomarker referring to the therapeutic effect of rewarming for severe hypothermia caused by seawater immersion.

Dive Performance and Aquatic Thermoregulation of the World's Smallest Mammalian Diver, the American Water Shrew (Sorex palustris).

Allometry predicts that the 12-17-g American water shrew (Sorex palustris)-the world's smallest mammalian diver-will have the highest diving metabolic rate coupled with the lowest total body oxygen storage capacity, skeletal muscle buffering capacity, and glycolytic potential of any endothermic diver. Consistent with expectations, and potentially owing to their low thermal inertia, water shrews had a significantly higher diving metabolic rate in 10°C water (8.77 mL O2 g-1 h-1) compared with 30°C water (6.57 mL O2 g-1 h-1). Unlike larger-bodied divers, muscle myoglobin contributed minimally (7.7%-12.4%) to total onboard O2 stores of juvenile and adult water shrews, respectively, but was offset by high blood O2 carrying capacities (26.4%-26.9% v/v). Diving was predominantly aerobic, as only 1.2%-2.3% of dives in 10°C and 30°C water, respectively, exceeded the calculated aerobic dive limits at these temperatures (10.8-14.4 s). The mean voluntary dive time of water shrews during 20-min trials in 3°C-30°C water was s (, ), with a mean maximum dive time of s. However, the average dive duration ( s, ) of radio-telemetered shrews exclusively foraging in a simulated riparian environment (3°C water) for 12-28 h suggests that mean (but not maximum) dive times of water shrews in the wild may be longer. Mean dive duration, duration of the longest dive, and total time in water all decreased significantly as water temperature declined, suggesting that shrews employed behavioral thermoregulation to defend against immersion hypothermia. Additionally, free-diving shrews in the 24-h trials consistently elevated core body temperature by ∼1°C immediately before initiating aquatic foraging bouts and ended these bouts when body temperature was still at or above normal resting levels (∼37.8°C). We suggest that this observed predive hyperthermia aids to heighten the impressive somatosensory physiology, and hence foraging efficiency, of this diminutive predator while submerged.

Влияние разных режимов охлаждения (краниоцеребральной и иммерсионной гипотермии, поверхностных ритмических и экстремальных холодовых воздействий) на лейкоцитарные показатели крови крыс

A comparative analysis of leukocyte types number in rat blood smears at the craniocerebral (CCH 32°C) and immersion (IH 27°C) hypothermia, surface rhythmic cold exposures (RCEs 5°C) and whole body cryostimulation (WBC –120°C), as well as in 24 hrs revealed the leukocytosis (at IH and 24 hrs after CCH and IH), leukopenia (at CCH, RCEs and 24 hrs after WBC), lymphopenia, an increase in band and segmented cells (under all conditions except IH) and eosinophils (only at CCH and 24 hrs after WBC). Plasmatic cells (except WBC), polychromatophilic and immature cells (immediately and in 24 hrs after CCH and IH), cytoplasm plasmatization in some leukocytes (24 hrs after CCH and IH) were observed. Leukocyte indices showed the immunoreactivity disorder, decreased allergization, activation of cell immunity, nonspecific cell protection and inflammation (under all conditions, except IH), as well as microphages (at WBC and 24 hrs after CCH and IH), an effector component of immunity (at CCH, RCEs and 24 hrs after WBC), immediatetype hypersensitivity responses (except at CCH and 24 hrs after WBC). The nuclear shift index was increased (except RCEs and WBC). The adaptation index was raised only at IH. Probl Cryobiol Cryomed 2018; 28(4): 293-310

ВЛИЯНИЕ ОБЩЕГО ОХЛАЖДЕНИЯ ГОМОЙОТЕРМНОГО ОРГАНИЗМА НА ЭРИТРО- И ЛЕЙКОЦИТАРНЫЕ ПОКАЗАТЕЛИ КРОВИ

The objectives of the study were the investigation of reactions of the erythrocyte and leukocyte links of rat’s blood under general immersion hypothermia (IH). Methods. The IH was simulated by “forced swimming” test in cold water (0°C, 5 min, down to 27°C). The dynamics of erythrocyte transformation and distribution of their shapes were studied by a small-angle light scattering method. The types and number of leukocytes were determined in blood smears. The transformation indices of erythrocytes (ITE) and integral leukocyte indices (ILI) were calculated. Results. Under IH a decrease in the number of discocytes and an increase in erythrocytes altered forms were observed; the values of transformation indices, reversible and irreversible transformations were increased. The development of IH was accompanied by leukocytosis and a decrease in the number of segmented neutrophils on the background of the stab cells increase. The young, plasmatic and polychromatophilic cells as well as cytoplasm plasmatization in single leukocytes were noted. Calculation of ILI revealed activation in tissue destruction processes, immediate type of hypersensitivity and an increase in the Garkavi adaptation index. On the contrary, 24 hrs after the IH, the proportion of the discocytes increased on the expense of highly resistant flattened discocytes appearance, and the proportion of altered cells decreased due to their elimination from the blood. The values of the indices of transformation, reversibility and reversible transformation were decreased, but the index of irreversible transformation has increased by an order of magnitude. Twenty four hrs after the IH, the leukocytosis and the increase in the stab neutrophils against the background of lymphopenia as well as the appearance of young cell forms, polychromatophils and plasmatic cells were noted. Changes in ILI indicated the activation of the cellular link of the immune system, specific defense cells, delayed type hypersensitivity processes and macrophage system components, tissue decay processes, intoxication and allergisation. Conclusions. General immersion hypothermia significantly altered the quantitative and qualitative ratios of the shapes and types of blood cells in rats, affected the processes of erythrocyte transformation and the activation of distinct immunity links (according to the calculation of ITE and ILI, respectively). The direction and intensity of these changes depend on the terms of observation (immediately and 24 hrs after cooling).

Influence of cooling medium on rat hemostatic system

The purpose of the article is to study the effect of air and water-immersion cooling media on the hemostatic system in the pre-active period of cold trauma. Material and methods. The study was performed on 43 laboratory Wistar rats. Single air hypothermia was modeled by placing animals in individual cells into a cooling chamber at a temperature –25 °С. The animals were in the chamber until the rectal temperature reached 30 °C, which corresponded to a moderate degree of hypothermia in rats. Water immersion hypothermia was modeled by placing animals in individual cells into water with a temperature 5 °C and air 7 °C. The criterion for cessation of exposure was a rectal temperature of 27–30 °C, which also corresponded to a moderate degree of hypothermia. We assessed the state of vascularplatelet and plasma hemostasis, as well as the physiological state of anticoagulant and fibrinolytic systems. The study was performed by using routine techniques and an integral method - thromboelastography. Results. It was established that during water immersion cooling, experimental animals developed thrombocytosis and activated their aggregation function. Laboratory indicators characterizing the initial stages of plasma hemostasis, and external and internal ways of activation did not change at this intensity of hypothermic exposure. At the same time, at the final stage of coagulation, pronounced thrombinemia was recorded, which was confirmed by a significant increase in the concentration of soluble fibrin-monomer complexes and a decrease in the time of their self-assembly. In addition, inhibition of fibrinolytic activity of plasma associated with a decrease in the concentration of antithrombin III was observed. In this case, single air hypothermia, accompanied by the rise in a rectal temperature up to 30 ° C, also caused significant changes in the hemostatic system. Vascular-platelet hemostasis responded to a significant decrease in aggregation activity of platelets. In plasma hemostasis, the final stage of coagulation was involved the most, which was manifested in hypocoagulant shifts. Along with this, pronounced inhibition of fibrinolytic activity of blood plasma was recorded. Thus, the described hemostasiological pictures indicate a pronounced influence of the environment causing supercooling on the response of an organism with hypothermia. In case of immersion hypothermia an increase in a rectal temperature up to 30 oС is accompanied by a pronounced activation of the coagulation processes and the thrombotic state of readiness. When supercooling with air after reaching a rectal temperature of 30 ° C, secondary hypocoagulation shifts are recorded.

Effect of Hypothermia-Induced Respiratory Arrest on Cerebral Circulation in Rats.

Intravital microscopy was employed to examine cerebral circulation in rats assessed by blood flow in the venules with diameter of 10-30 μ during immersion hypothermia continued to the moment of respiratory arrest and for 10 min thereafter. Circulation in the cerebral microvessels continued during severe hypothermia, and it went on even after hypothermic respiratory arrest while the heart was beating. In pial venules, the blood continued to fl ow for 8-10 min after respiratory arrest.

Motor and sensory effects of ipsilesional upper extremity hypothermia and contralesional sensory training for chronic stroke patients

As hypothermia by immersion can reduce the sensory nerve conduction velocity, this study hypothesized that the reduction of sensory input to the ipsilesional upper extremity (UE) using cryotherapy would reduce the inhibitory activity of the contralesional hemisphere in chronic stroke subjects.Objective:In this study, hypothermia was applied by immersing the ipsilesional UE in association with sensory training of the contralesional UE of stroke patients to assess the immediate (e.g. sensorimotor function, hemodynamics, and levels of comfort) and long-term (sensory and motor performances of the UEs) effects.Methods:The sample included 27 stroke patients allocated into group 1 (n = 14), which received conventional physiotherapy for the affected UE, and group 2 (n = 13), which underwent 10 sessions of immersion hypothermia of the ipsilesional wrist and hand. Assessments were performed pre- and post-treatment and at follow-up using esthesiometry, the Fugl–Meyer Assessment (FMA), the Nottingham Sensory Assessment, functional tests, tactile and weight discrimination, motor sequence, level of comfort, and hemodynamic parameters.Results:The immediate effects of hypothermia using immersion of the ipsilesional UE in association with sensory training of the contralesional UE were hemodynamic stability during and after hypothermia, the absence of sensory abnormalities in the contralesional UE, hypoesthesia in the ipsilesional extremity (dermatomes C6 and C8) (P < 0.05), the maintenance of acceptable levels of comfort, and good patient compliance to the technique. The long-term effects included significant increases in scores on tests performed without functional vision, in scores on blindfolded functional tests, and in tactile localization and joint position sense for the contralesional hand in group 2 as well as the maintenance of these gains at long-term follow-up (5 weeks). Improvement was also found in the tactile function of the C6 and C7 dermatomes of the contralesional hand (P < 0.05).Conclusions:The use of immersion hypothermia on the ipsilesional UE in association with sensory training of the contralesional UE improved motor function and sensitivity in the contralesional UE of individuals with chronic stroke. Immersion hypothermia of the ipsilesional UE in chronic stroke patients is a safe, practical, inexpensive, and easily applied technique.

Erythrocytes of hetero- and homoiothermic animals under natural and artificial hypothermia

Using low-angle light scattering technique, the features of erythrocyte transformation dynamics (osmotic fragility, the hemolysis level and ratio of different cell forms determined by the spherical index) were revealed in hetero- (golden hamsters Mesocricetus auratus) and homoiothermic (white rats Rattus norvegicus) animals under natural (hibernation) and artificial (suspended animation) hypometabolic states, craniocerebral and immersion hypothermia. In control, golden hamsters exhibited higher levels of erythrocyte osmotic fragility and hemolysis than rats, with transformed erythrocytes (especially stomatocytes) being prevalent. Under artificial hypothermia, regardless of the way of its attaining, depth and duration, the changes were observed that were similar in their directionality but dissimilar in the degree of manifestation: increased osmotic fragility and hemolysis, reduced portion of discocytes (particularly sharp in golden hamsters under suspended animation), increased number of transformed erythrocytes. In contrast, under hibernation the osmotic fragility, hemolysis and number of stomatocytes decreased, the portion of discocytes increased, while the number of prehemolytic forms (spherocytes) also increased. In 24 h, both the osmotic fragility (stronger in hamsters after suspended animation) and the level of hemolysis (particularly after immersion hypothermia) decreased, the portion of discocytes recovered (even exceeding the control level in hamsters after suspended animation and in rats after immersion hypothermia), spherocytes were not detectable in hamsters but elevated in rats. It is likely that the qualitative changes in the erythrocyte population towards its homogeneity detected 24 hours after hypothermia may be mediated not only by the elimination of old and defective cells, erythropoiesis activation and production of high-resistant erythrocytes but also by the fine membrane-stabilizing mechanisms.

The Oldest Anaesthesiologist on the Balkan Peninsula, Dr. Risto Ivanovski, Died

Dr. Risto Ivanovski died on 17 of June 2013 in his 100-th year of life. He was the first anaesthesiologist in Republic of Macedonia and one of the founders of modern anaesthesiology in ex-Yugoslavia. He was born in Prilep, Macedonia. He started to make his way in the field of anaesthesiology in 1946. Then, Yugoslavia, as a part of the antifascist coalition, received aid in medical personnel and equipment through UNRRA. Dr. Patrick Shackleton, and Dr. Rasel Davies from Great Britain educated the first group Yugoslav doctors in the field of anaesthesiology. Then, the Army sent him to organize the anaesthesiology service at the Military Hospital in Zagreb, but because he was the only one anaesthesiologist in Croatia, numerous well-known surgeons addressed him to work together in different hospitals in Zagreb, Osijek and Rovinj). From 1954, Dr. Ivanovski worked at the Military Hospital in Skopje. He was the teacher of the first generation of Macedonian anaesthesiologists. In 1959 he was elected as an Associate Professor at the Medical Faculty in Skopje. He was also a visiting anaesthesiologist in Prishtina, Kosovo. Dr. Risto Ivanovski was the first president of the Macedonian Society of Anaesthesiology founded in 1962. His professional opus contains about 20 works where he spoke about current problems of his time; the beginnings of endotracheal intubation, the use of Viadril cyclopropane and plasma expanders, immersion hypothermia as an addition to general anaesthesia in high-risk patients, organization problems of anaesthesiology services in war etc. Dr Risto Ivanovski left numerous admirers. The generations that followed his time, respect his efforts and work.

Cognitive Function During Lower Body Water Immersion and Post-Immersion Afterdrop

The physiological effects of immersion hypothermia and afterdrop are well-characterized, but the psychological effects are less clear. The purpose of this study was to quantify changes in cognitive function during and after lower body water immersion. On separate mornings, nine young healthy men participated in both neutral (35 +/- 1 degree C) and cold (13 +/- 1 degree C) water immersion. Subjects rested in neutral air for 30 min followed by 60 min water immersion to the iliac crest and 15 min of recovery in neutral air. Rectal temperature and mean skin temperature were continuously monitored. Metabolic rate, the Stroop Color Word Test (SCWT), and the Profile of Mood State (POMS) were quantified at predetermined intervals. During immersion in cold water, rectal temperature was reduced, but SCWT and POMS scores were unchanged relative to baseline. Despite the reduced rectal temperature, little to no shivering was observed during immersion and metabolic rate did not change. During recovery from cold immersion, rectal temperature was further reduced by approximately 0.5 degree C, shivering was noted, and metabolic rate increased. Coincident with this acute afterdrop, SCWT Color-Word performance (delta = -4 +/- 8 vs. 7 +/- 6 correct responses) and Interference score (delta = -2 +/- 7 vs. 4 +/- 8) was impaired relative to recovery from neutral immersion (i.e., when core temperature and metabolic rate did not change). These results suggest that recovery from lower body cold water immersion elicits the afterdrop phenomenon and shivering, which together impair selective attention as measured by the SCWT.

Respiration Restitution in Rats Following Its Termination in Immersion Hypothermia

Rats were cooled in water until attaining profound hypothermia and respiratory arrest. After removal from water, 0.5% solution of Na2EDTA was administered intravenously. This led to a drop of blood [Ca2+] by 20-30% from the baseline and promoted recovery of respiration following its arrest lasting 10.3±1.4 min. By the 30th minute of Na2EDTA administration, respiration rate increased to 32.3±5.2 cycles per minute and respiration amplitude reached 68±4% of the baseline level. This effect was observed without special warming of the rats. It was concluded that the period during which the organism maintains viability in respiration arrest and disturbances in respiratory center are still reversible is prolonged under conditions of profound hypothermia.

Ultrastructural Organization of Capillaries in Various Compartments of the Dog Heart in Artificial Immersion Hypothermia

Similarity of the structural characteristics of perfusion capacity of right-atrial and left-ventricular capillaries of the dog heart in health were detected, the capillaries differing significantly by size and by the majority of the morphometrical values. Exposure of animals to hypothermia induces different ultrastructural responses of the capillaries in two compartments of the heart: the perfusion characteristics of the right atrium deteriorate and the morphometrical parameters of endotheliocytes change, while in the left ventricle the population composition of endothelial cells changes significantly (the percentage of cells of the main type reduces, while the share of dark cells increases).

Body cooling and the diving capabilities of muskrats ( Ondatra zibethicus): A test of the adaptive hypothermia hypothesis

We tested the hypothesis that immersion hypothermia enhances the diving capabilities of adult and juvenile muskrats by reducing rates of oxygen consumption (V˙O 2). Declines in abdominal body temperature ( T b) comparable to those observed in nature (0.5–3.5 °C) were induced by pre-chilling animals in 6 °C water. Pre-chilling did not reduce diving V˙O 2 of any animal tested in 10 °C or 30 °C water, irrespective of the nature of the dive. Most behavioural indices of dive performance, including average and cumulative dive times, were unaffected by T b reduction in adults, but depressed in hypothermic juveniles (200–400 g). Hypothermia reduced diving heart rate only on short (< 25 s) dives (16% reduction, P = 0.01), but did not affect the temporal onset of diving bradycardia. Post-immersion V˙O 2 was higher for pre-chilled than for normothermic muskrats, but the difference became insignificant on longer (> 90 s) dives. Our findings suggest that the mild hypothermia experienced by muskrats in nature has minimal effect on diving and post-immersion metabolic costs, and thus has little impact on the dive performance of this northern semi-aquatic mammal.

Surgical palliation of hypoplastic left heart syndrome: is there a role for hypothermic circulatory arrest?

The technique of deep hypothermia with circulatory arrest has been important in the history of the evolution of cardiac surgery. Wilfred G. Bigelow, working in Toronto in the late 1940s, performed pioneering research on hypothermia, and developed a workable technique of hypothermia in human cardiac surgery.1Based upon Bigelow's experimental premises, F. John Lewis, at the University of Minnesota, also conducted a number of experiments utilizing hypothermia. On September 2, 1942, Lewis operated on a 5-year-old girl with an atrial septal defect under general hypothermia with inflow occlusion. He was assisted by Richard Varco, Mansur Taufic, and C. Walton Lillehei. Rubberized refrigerated blankets were used to cool the patient to 28°C. The septal defect was closed during five and a half minutes of inflow occlusion. This was the world's first successful open operation on the human heart performed under direct vision, and marked the beginning of the era of open heart surgery. Now, as amazing and as primitive as that methodology may seem, those of you who read Life magazine, or watch the Discovery Channel on television, are aware that, in parts of the Soviet Union, a large fraction of today's open heart surgery is performed not using the technique of cardiopulmonary bypass, but rather using the methodology of immersion hypothermia from the 1950s, with surprisingly good results.

In vivo high-efficiency transcoronary gene delivery and Cre-LoxP gene switching in the adult mouse heart.

High-efficiency somatic gene transfer in adult mouse heart has not yet been achieved in vivo. Here, we demonstrate high-efficiency in vivo transcoronary gene delivery to the adult murine myocardium using a catheter-based technique with recombinant adenovirus (AdV) and adeno-associated virus (AAV) vectors in normal and genetically engineered mice. The method involves immersion hypothermia followed by transient aortic and pulmonary artery occlusion with proximal intra-aortic segmental injection of cardioplegic solution containing substance P and viral vectors. Gene expression measured using a LacZ marker gene was observed throughout both ventricles. The expression efficiency of a cytoplasmic LacZ marker gene in the left ventricular myocardium was 56.4+/-14.5% (mean+/-s.d.) at 4 days with an AdV vector, and with an AAV vector it was 81.0+/-5.9% at 4 weeks. Following AAV gene transfer, no gene expression was found in kidney, brain, lung, and spleen, but there was slight expression in liver. In addition, we demonstrate temporally controlled genetic manipulation in the heart with an efficiency of 54.6+/-5.2%, by transferring an AdV vector carrying Cre recombinase in ROSA26 flox-LacZ reporter mice. Procedure-related mortality was 16% for AdV and zero for AAV transfer. Thus, this method provides efficient, relatively homogeneous gene expression in both ventricles of the adult mouse heart, and offers a novel approach for conditional gene rescue or ablation in genetically engineered mouse models.

Cardiopulmonary resuscitation following profound immersion hypothermia.

A case is presented in which prolonged resuscitation and rewarming was performed following post-rescue cardiopulmonary arrest in severe immersion hypothermia. The rescue and resuscitation techniques necessary to optimise outcome in...