Inter-species differences in hematocrit to blood viscosity ratio.

Hematocrit (Hct) is the major determinant of whole blood viscosity and of its oxygen binding capacity: with increasing Hct, viscosity increases exponentially and oxygen capacity increases linearly. Thus, the theoretical oxygen transport potential of blood, as indexed by the ratio of Hct to viscosity (Hct/viscosity), generally yields a curve concave to the Hct axis with a maximum at an "optimal hematocrit" value. This study analyzed relations between Hct, blood viscosity and shear rate for rats and dogs to explore whether different optima exist for Hct or Hct/viscosity. Our results reveal differences depending on both shear rate and species: at equal Hct, rats had higher blood viscosity and thus lower Hct/viscosity levels. Optimum values for Hct/viscosity were markedly different between the two species at shear rates of 90 and 200 s-1. Conversely, Hct/viscosity data at 10 s-1 did not exhibit an optimum but rather a linear decrease of the ratio with increasing hematocrit. Relations between Hct and blood viscosity thus differ among animal species. Inasmuch as animal studies are often utilized as an aid to understanding hemorheological aspects of clinical conditions and/or therapy, evaluating Hct/viscosity ratios may be a useful supplementary tool for research focused on various physiological and patho-physiological processes.

Hemorheological changes caused by intermittent Pringle (Baron) maneuver in beagle canine model.

In liver resection operations the Pringle (Baron) maneuver can be used for temporary ischemia by clamping the hepatoduodenal ligament intermittently. In this beagle canine model we investigated whether hemorheological parameters may alter in systemic, portal and hepatic venous blood and in arterial samples during-after Pringle maneuvers. In Pringle Group unilateral femoral artery and external jugular vein were cannulated. From median laparotomy the hepatoduodenal ligament was exposed. The portal venous system was catheterized via a mesenteric vein and through the inferior caval vein a catheter was led to the hepatic veins. After stabilization, a 15-minute Pringle maneuver was carried out three times with 5-minute interpolated reperfusion periods. In Control Group Pringle maneuvers were not made. Before and after Pringle maneuvers parallel blood samples were taken from the cannulated vessels for determining hematological parameters and erythrocyte aggregation. Following Pringle maneuvers erythrocyte deformability, blood and plasma viscosity were also tested. The results showed that besides systemic hemorheological effects of the intermittent Pringle maneuver local leukocyte count, hematocrit and erythrocyte aggregation index altered mainly in portal venous blood, depending on the repeating number of the maneuvers. Thus, investigations of hemorheological parameters might be useful to determine the optimal duration of the Pringle maneuver.

The effects of renal ischemia-reperfusion on hemorheological factors: preventive role of allopurinol.

Changes in hemorheological parameters were studied in dogs following unilateral renal artery clamping (45-minute ischemia then reperfusion), with and without preoperative administration of allopurinol. Sham-operated animals were also evaluated. Blood samples were collected preoperatively, at beginning and at 30, 60 and 120 minutes of reperfusion, then on the 1st, 3rd, 5th and 7th days. Filtration properties of erythrocytes (relative cell transit time, RCTT), whole blood and plasma viscosity (WBV, PV), fibrinogen level and hematology parameter were determined. RCTT significantly increased for both ischemic groups at 30 minutes of reperfusion, and remained elevated on the 1st and 2nd postoperative days; these changes were abolished by allopurinol pretreatment. WBV and hematocrit increased on the 1st day, and PV and fibrinogen level showed elevation on 1st-5th postoperative days. We thus conclude that decreases of RBC deformability (i.e., higher RCTT) were characteristic and specific on early postoperative days after renal ischemia-reperfusion and that these alterations were prevented by pre-ischemia administration of allopurinol.

Adhesion formation with open versus laparoscopic cholecystectomy: an immunologic and histologic study.

BACKGROUND: This randomized study aimed to compare the reaction of the immune system to the process of postoperative adhesion formation after open and laparoscopic cholecystectomy. METHODS: In this study, 20 mongrel dogs were used: 10 each in the laparoscopic and open cholecystectomy groups. Blood and peritoneal lavage samples were taken up to postoperative day 14, followed by second-look laparoscopy and reoperation to detect the rate of adhesion formation. Also, specimens were obtained from the liver bed for histology. RESULTS: In the open cholecystectomy group, the white blood cell count was higher in blood samples and lower in lavage specimens. Adhesion formation was extensive, and the histologic immune reaction was more intensive in the open cholecystectomy group. CONCLUSION: This randomized study proved that laparoscopic cholecystectomy was associated with less immune suppression, less inflammatory reaction, and therefore less adhesion formation than open cholecystectomy.

Local and systemic hemorheological effects of cerebral hyper- and hypoperfusion in a porcine model.

Using a well defined pig model, we investigated whether cerebral hypertension and hypotension influence hemorheological factors. After surgical preparation and stabilization, periods of hyperventilation, controlled periods of cerebral perfusion pressure increases and decreases were utilized. After each period, blood samples were collected from the cannulated femoral artery and vein, and from the superior sagittal sinus. Erythrocyte deformability, whole blood and plasma viscosity and hematological parameters were determined. Erythrocyte deformability significantly worsened in arterial samples after hypertension and hypotension, and in sinus samples it was impaired after hypotension period. Hematocrit significantly increased in arterial and sinus samples during hypertensive period, accompanied by similar alterations in whole blood viscosity. We conclude that hemodynamic changes caused by hyperventilation, hyper- or hypotension can influence hemorheological factors, and suggest that the rheological alterations can affect local hemodynamic and metabolic conditions.

A new concept for esophageal resection--prevascularization: an experimental study.

We aim to elaborate upon a basically new animal model for esophageal resection. A total of 17 operations on 10 dogs were performed in order to develop a model in which resection of the cervical part of the esophagus involves two steps. The first step comprises omental flap transplantation from the abdomen to the cervical region by a microsurgical method, this omental flap improving the blood supply to the organ (prevascularization). The second step is segmental resection of the esophagus 14 days later. Of the five transplanted grafts, four still survived one week after the operation; for technical reasons, one flap had thrombotized. In the two long-term survival cases with esophageal resection after prevascularizastion, there were no major complications: the resections were successful, and the omental flap 'grew into' the tissue structure of the esophagus, assisting the healing of the anastomosis. Segmental resection of the cervical part of the esophagus was performed successfully via a new type of operation on dogs.

Systemic and regional hemorheological consequences of warm and cold hind limb ischemia-reperfusion in a canine model.

We have studied systemic and regional changes in hemorheological parameters after complete acute limb ischemia and reperfusion (I/R) in 24 mongrel dogs. Unilateral cooled and non-cooled vascular ischemia (3 h)-reperfusion (4 h), and sham-operations were performed. Blood samples were collected from the excluded region, during reperfusion and for 5 days. Whole blood and plasma viscosity (WBV, PV), relative cell transit time (RCTT) of erythrocytes, fibrinogen level and hematological parameters were determined. In I/R groups WBV of excluded blood was significantly higher compared to the base (p < 0.05), and RCTT increased during the reperfusion. On 2nd-3rd days RCTT increased significantly in both I/R groups. In each group PV and fibrinogen showed continuous increase during the postoperative period, prominently in cooled I/R group, and furthermore WBV corrected for hematocrit (40%) was the highest in cooled I/R group. These suggest that surgical acute limb I/R may cause hemorheological changes, which are more serious after cooling. (Grants: OTKA-T032571, 6003/1/2001/ETT.)

Basic teaching in microsurgery.

We summarize our 15 years of educational experience in the field of teaching microsurgery. The students can be divided into three groups: (1) medical students, (2) researchers, (3) medical doctors and specialists. Characteristics of our method include the following: activity, synchronism, video-assistance, self-controlling, individualization, analysis. The Furka microsurgical educational method, named after one of the authors, is 20 hours long (five 4-hour sessions). The first lesson allows students to become acquainted with the microsurgical instruments. The next lesson consists of learning the probe of layer-feeling. The third lesson is to learn how to produce stitches under the microscope. The fourth lesson includes arterial anastomosis preparation on fresh arterial pieces of animal origin. The fifth lesson means a quality change from previous classes, as practice is performed on living animals, generally rats. The teaching of microsurgical basics requires both patience and empathy. The teaching process is most successful if one teacher deals with a maximum of two students.

Spleen autotransplantation in mice: a novel experimental model for immunology study.

The aim of the experimental model to develop a spleen transplant model in mice to study the role of spleen in autoimmune and transplant rejection. After a midline incision, splenectomy was performed. Four tiny segments were cut from the removed spleen and were rinsed at room temperature in physiological salt solution. The greater omentum was lifted and four omental pockets were created; four thin segments were then placed into the "nests," subsequently marked, and fixed using 8-0 suture. The abdomen was then closed. The duration of the survival time was different among the nine groups (n = 3-3). Tissue samples were taken from the marked areas for histological examination stained with hematoxylin and eosin (H&E). H&E staining demonstrated large, well-circumscribed splenic nests with lymphoid zone and red pulp and well-formed trabecules in the spleen. Among the possible applications of this novel model is the ability to study the role of spleen in autoimmune and organ rejection.

The influence of intraoperative complications on adhesion formation during laparoscopic and conventional cholecystectomy in an animal model.

BACKGROUND: The aim of this study was to evaluate the extent of postoperative adhesion formation after laparoscopic and open cholecystectomy. MATERIALS AND METHODS: Qualified surgeons performed 60 experimental laparoscopic cholecystectomies (LC) in dogs with the aim to acquire the laparoscopic technique. To assess the relation between the complications during the operation (bleeding, laceration of the liver bed, or gallbladder perforation) and the formation of adhesions, surviving animals were divided into four groups according to the type of complication occurred. Assessment of the results was made by second-look laparoscopy 4 weeks after LC using the adhesion index (AI; score range, 0-4). The animals then were killed so the extent of adhesion formation could be measured. As a control, open cholecystectomy was performed in 15 dogs without intraoperative complications. The Mann-Whitney rank-sum test and Dunn's method were used for statistical analysis. RESULTS: No adhesion formation or intraoperative complications were registered in the laparoscopic group I. In all the cases wherein bleeding or laceration of the liver bed occurred and was managed with electrocoagulation, adhesions formed. Adhesion formation in these groups was significantly higher than in "ideal LC" or cases of gallbladder perforation alone (p < 0.01). All the animals in the control group developed significantly more adhesions than those in the experimental group (p < 0.05). CONCLUSIONS: It seems that LC has a lower rate of adhesion formation than the conventional open technique. Complications such as bleeding or laceration of the liver bed during LC can enhance adhesion formation. No adhesion formation can be mentioned in relation to gallbladder perforation during LC.

[Effect of pentoxifylline on the healing of experimental anastomosis of the left colon in rats]. / A pentoxifyllinum hatása a kísérletes bal colonfél anasztomózis gyógyulására.

The healing of colonic anastomoses is determined by several factors such as microcirculation, the strength of the inflammatory response, and the time required for regeneration. We investigated the effects of pentoxifylline--a drug which improves microcirculation and modulates leukocyte functions--on the healing of experimental anastomosis on the left colon of rats. As a result of drug treatment (0.25 mg/100 g, i.p.) in Group I anastomosis bursting pressure (ABP) was by 56 +/- 17% higher at day 2 than in controls with no pentoxifylline treatment. On the 5th postoperative day in Group I, ABP reached 80 +/- 8% the value for the intact colon (218 +/- 21 mmHg), whereas respective value in the control (untreated) group was only 47 +/- 7%. In Group II (pentoxifylline: 2 mg/100 g, i.p.) ABP was by 55 +/- 10% and by 73 +/- 8% higher than control values at postoperative days 1 and 2, respectively. At day 2, in Group I colonic blood flow measured at the anastomosis line by 86Rb uptake technique was significantly higher than in the untreated controls (0.18 +/- 0.01 ml/min vs. 0.14 +/- 0.01 ml/min, (p < 0.02). Blood flow measured in colon tissue above and below the anastomosis changed differently. Pentoxifylline treatment also suppressed the peritoneal inflammatory response assessed with peritoneal reaction index (2.0 +/- 0.3 vs. 1.1 +/- 0.2, p < 0.01). The results of the present study show that pentoxifylline treatment shortens the time needed for the healing of colonic anastomosis. These observations suggest that pentoxifylline medication can prevent failure of colonic anastomoses.

[How do intraoperative complications effect adhesion formation after laparoscopic cholecystectomy: a comparative animal study]. / Az intraoperatív szövódmények hatása a posztoperatív hasúri adhesiók kialakulására laparoszkópos cholecystectomiát követóen: összehasonlító állatkísérlet.

BACKGROUND: The aim of this study was to evaluate the extent of postoperative formation of adhesions following laparoscopic and open cholecystectomy. MATERIAL AND METHODS: 60 experimental laparoscopic cholecystectomies (LC) were performed in dogs by qualified surgeons to learn laparoscopic technique. To assess the relationship between complications occurred during the operation (bleeding, laceration of the liver bed or gallbladder perforation) and the formation of adhesions surviving animals were divided into 4 groups according to the type of complication. We assessed the results during second-look laparoscopy 4 weeks following LC using the adhesion index (AI: 0-4 score). Animals were then sacrificed to measure the extent of adhesions. As a control group open cholecystectomy was performed in 15 dogs without intraoperative complications. Mann-Whitney Rank Sum test and Dunn's Method were used for statistical analysis. RESULTS: No adhesions were observed in the laparoscopic group without intraoperative complications. In all dogs with bleeding or laceration of the liver bed maintained by electrocoagulation, adhesions developed. Formation of adhesion in these groups was significantly higher than in "ideal LC" or in case of gallbladder perforation (P < 0.01). All animals in the control group developed significantly more adhesions compared to the experimental group (p < 0.05). CONCLUSION: LC produces less adhesion compared to conventional open technique. Complications such as bleeding or laceration of the liver bed during LC can increase the formation of adhesions. No formation of adhesions can be related to gallbladder perforation during LC.

Effects of electrical stimulation of the Gasserian ganglion on regional cerebral blood flow after induced subarachnoid hemorrhage in pigs evaluated by 99mTc-HMPAO-SPECT.

It could be demonstrated that cervical spinal cord stimulation increases cerebral blood flow. The effects of electrical stimulation of the trigeminal ganglion in the acute phase of SAH in pigs were investigated. The experiments were carried out on 11 domestic pigs divided in two groups (group I: SAH [n = 5]; group II: SAH and trigeminal stimulation [n = 6]). In all animals a native SPECT was performed. The Gasserian ganglion was exposed for inserting the stimulation electrode. SAH was induced by injecting 10 ml autologous blood through a catheter placed in the suprasellar cistern. 30 minutes after SAH-induction electrical stimulation was started for two hours in group II (2.8-4.5 V, 50 Hz, 300 microseconds). 99mTc-HMPAO (400-540 MBq) was injected intravenously 110 minutes later. In group I 99mTc-HMPAO was applied after the same time interval. 80 minutes later SPECT was performed. Data were processed to calculate the uptake of radioactivity (%/kg tissue weight). The mean values were calculated for the different groups: native animal examination (%/kg tissue weight): 0.6343; group I: 0.468; group II: 0.6533. Comparing the mean values a highly significant difference between group I and group II (p < 0.01) and between native examination and group I (p < 0.01) could be found. No statistical significance could be detected on comparing the left/right-ratio in any ROI. The electrical stimulation of the Gasserian ganglion leads to a significantly increased uptake of 99mTc-HMPAO after induced SAH. Maybe the stimulation of the Gasserian ganglion constitutes a new therapeutic modality treating disturbed rCBF after SAH.

Cerebrovenous blood temperature-influence of cerebral perfusion pressure changes and hyperventilation: evaluation in a porcine study and in man.

The objective of the first part of this study was to use an animal model to investigate the relationship between temperature in the cerebrovenous compartment and cerebral perfusion pressure. In the second part of the study, the objective was to examine the influence of hyperventilation and hypothermia on jugular bulb temperature and body temperature in patients undergoing elective neurosurgery. Intracranial pressure was increased artificially by inflating an infratentorial supracerebellar placed balloon catheter in nine pigs under general anesthesia. Temperature was monitored by thermocouples inserted in the sagittal sinus, white matter of the left lobe and abdominal aorta during the ensuing decrease in cerebral profusion pressure (CPP). Cerebrovenous blood temperature (jugular bulb) and body temperature (urinary bladder) were simultaneously monitored in 24 patients undergoing craniotomy. Moderate hyperventilation was performed in all patients. Cerebrovenous blood and core body temperature were recorded and differences between these two temperatures calculated at the beginning and the end of hyperventilation. At the beginning of the intracranial pressure (ICP), increase mean temperatures of cerebrovenous blood and cerebral tissue (left lobe) were lower than core body temperature. During CPP reduction the difference between core body temperature and cerebrovenous blood temperature increased significantly from 0.86+/-0.44 degrees C prior to ICP rise to 1.19+/-0.58 degrees C at maximum ICP. Before hyperventilation, cerebrovenous blood temperature was higher in 19 patients (+/- difference: 0.34 degrees C +/- 0.27) and equal or lower in five patients (difference: -0.08 degrees C +/- 0.11), than core body temperature. At the end of hyperventilation, the difference between cerebrovenous blood temperature and core body temperature increased (+0.42 degrees C +/- 0.24) in those 19 patients who had started with a higher cerebrovenous blood temperature and decreased (-0.10 degrees C +/- 0. 18) in the other five patients. Both studies demonstrated that the temperature of cerebrovenous blood is influenced by maneuvers which are supposed to decrease cerebral blood flow.

The judgement of adhesion formation following laparoscopic and conventional cholecystectomy in an animal model.

INTRODUCTION: The development of postoperative adhesions remains an almost inevitable consequence of visceral and gynaecologic surgery, appearing in 50-95% of all patients. Although decreased adhesion formation is one of the accepted advantages of laparoscopic surgery, only a small number of prospective studies have been done to support this claim. AIMS OF THE STUDY: To evaluate the extent of postoperative adhesion formation after laparoscopic and open cholecystectomy. MATERIAL AND METHOD: 60 experimental laparoscopic cholecystectomies (LC) were performed by qualified surgeons in dogs with the aim to acquire the laparoscopic technique. To assess the relation between the complications during the operation (bleeding, injury to the liver substance or gallbladder perforation) and the formation of adhesions, the surviving animals were divided into 4 groups according to the complications occurred. The assessment of the results was made by second--look laparoscopy 4 weeks following LC using the adhesion index. As a control group open cholecystectomy was then performed in 5 dogs without intraoperative complications. RESULTS: No adhesion formation was observed in the groups where no intraoperative complications occurred. In all the cases where bleeding or injury to the liver bed occurred adhesion formation occurred. No adhesion formation was observed in case of gallbladder perforation. In all the animals of the control group adhesion formation was observed. CONCLUSION: It seems that LC has a reduced rate of adhesion formation when compared with the open technique. Complications such as bleeding or injury to the liver substance during LC can enhance adhesion formation. No adhesion formation can be mentioned in relation with gallbladder perforation when the laparoscopic technique is applied.

The history and the future of teaching and training of laparoscopic surgery in Hungary.

INTRODUCTION: Laparoscopic biliary surgery was introduced in Hungary at the end of the 1990. A variety of experimental training and teaching courses had been performed in basic techniques and the human field, which was followed by laparoscopic biliary surgery and various advanced fields. AIMS OF THE STUDY: To review the history of teaching and training of laparoscopic surgery in Hungary in both the experimental and the human field, and to draw the consequences of this experience. MATERIAL AND METHODS: In a period of 6 years 704 qualified surgeons received a full hands--on hands experimental training in laparoscopic biliary surgery, laparoscopic advanced surgery, laparoscopic gynaecologic and laparoscopic urology surgery. DISCUSSION: The courses performed in the first and the second phase were of theoretical and practical components. The theoretical knowledge was based with emphasise to the new instruments and equipment, the indications, the new surgical technique. The practical knowledge gave every participant the full time to acquire this new type of surgery. At the end of the courses the successful participants received certificates to shift for training to the human field. Each institution needs to wrestle with issues concerning credentialling in advanced laparoscopic surgery. Like many technical skills, proficiency is maintained through repetition. A philosophy must be developed to determine whether each surgeon will perform this highly specialised type of surgery or whether it will be considered a general skill.

Is it useful to measure supratentorial ICP in the presence of a posterior fossa lesion? Absence of transtentorial pressure gradients in an animal model.

Previous studies with animal models of supratentorial ICP elevation have demonstrated a pressure gradient between the supratentorial and the infratentorial compartments. The present study was designed to investigate the possible presence of such a gradient in the case of infratentorial ICP elevation. An inflatable infratentorial balloon catheter was implanted in seven domestic pigs. The infratentorial ICP (ICPi) was measured in the left cerebellar hemisphere, and the supratentorial ICP (ICPs) was measured in the left cerebral hemisphere. The corresponding pulse amplitudes (ICPi-PA, ICPs-PA) were recorded in both compartments, and the cerebral perfusion pressure (CPP) was calculated. ICPi and ICPs values prior to balloon inflation were 4.4 (SD 2.2) and 4.1 (SD 2.3) mm Hg, respectively, and increased to 63.1 (SD 32.6) and 62.3 (SD 28.1) mmHg after balloon inflation. ICPi-PA rose from 3.1 (SD 0.43) to 12.8 (SD 8.0) mmHg, and ICPs-PA rose from 3.2 (SD 0.63) to 13.0 (SD 7.1) mmHg. CPP decreased from 86.1 (SD 12.0) to 55.4 (SD 14.6) mm Hg. The paired difference between ICPi and ICPs values was 0.44 (SD 1.96) mmHg, and the paired difference of ICP amplitudes was 0.03 (SD 1.19) mmHg. All these differences in infratentorial and supratentorial values were statistically not significant. In conclusion, infratentorial ICP elevation in the presented pig model leads to a uniform ICP elevation in the intracranial space without development of a considerable pressure gradient below and above the tentorium. In the low pressure part of the ICP curve, cerebrospinal fluid connects the compartments and contributes to the pressure equilibrium. The early obstruction of the foramen magnum by intruding cerebellar tissue seems to isolate the infratentorial from the spinal compartment. In the high-pressure part of the curve, the upwards cerebellar transtentorial herniation takes over the pressure transfer, and the whole intracranial space can be considered as a single compartment in the pig.

Simultaneous continuous measurement of pO2, pCO2, pH and temperature in brain tissue and sagittal sinus in a porcine model.

INTRODUCTION: The clinical use of brain tissue oxygen measurement in patients with severe head injury is increasing. It is important to compare the findings in brain tissue with cerebrovenous blood oximetry, to obtain normal values and to find out limitations of the method. We evaluated a newly available multisensor probe simultaneously in the brain tissue and in the sagittal sinus in a porcine animal model. METHODS: We placed the Paratrend 7-probe (BSL, High Wycombe, UK) in the left frontoparietal white matter and measured pO2 (PtiO2), pCO2 (ptiCO2), pH and temperature while simultaneously measuring these parameters (pcvO2, pcvCO2) in the sagittal sinus in 7 pigs under general anaesthesia during oxygen enhancement. RESULTS: The relation between oxygen increase in brain tissue and in the sagittal sinus showed a coefficient of correlation (CCmean) rmean = 0.96. The quantitative response in brain tissue was much more sensitive than in the sinus. A close correlation between pCO2 in brain tissue and sagittal sinus and the increase of the inspired oxygen was seen: CC ptiCO2 to arterial oxygen pressure (paO2) - rmean = 0.67, CC pcvCO2 to paO2 - rmean = 0.88. CONCLUSIONS: Measuring partial oxygen pressure in brain tissue is more responsive to physiological variations, and the absolute values are more sensitive than oxygen measurement in the cerebrovenous compartment. This is important for interpreting measured values and introducing new coefficients for patient monitoring.

Temperature of the cerebrovenous blood in a model of increased intracranial pressure.

UNLABELLED: Hypothermia has a considerable protective effect during brain ischemia. On the other hand small increases of brain temperature have a remarkable effect on the exacerbation of neurological damage following an ischemic event. Hyperthermia of the brain tissue after severe head injury is described. The effect of acutely increased intracranial pressure on cerebrovenous blood temperature is not described yet. The aim of this study was to investigate the relationship between temperature in the cerebrovenous compartment (Tcv) and changes of the CPP in an animal model of raised intracranial pressure. METHODS: A thermocouple was inserted in the sagittal sinus in 9 pigs under general anesthesia. By stepwise inflating a supracerebral and infratentorial placed balloon catheter intracranial pressure (ICP) was increased and CPP concomitantly decreased. The central body temperature was measured simultaneously in the abdominal aorta (Ta) with a second thermocouple. RESULTS: In our model th Tcv was lower than Ta at the beginning of the ICP increase. The mean difference between Ta and Tcv, (delta Ta-cv) was 0.86 degree C (+/- 0.44) prior to ICP increase and 1.19 degrees C (0.58) at the maximum ICP increase. Thus, delta Tav increased during CPP reduction. This relation was represented by an adjusted R(square) of r2 = 0.89 (p < 0.001). CONCLUSIONS: The CPP decrease, caused by an increasing ICP, results in changes of the cerebrovenous blood temperature. Interpreting the present results the experimental situation of a relative colder cerebral compartment in comparison to the central body temperature has to be considered. However, the results imply, that simultaneous temperature monitoring of the central body temperature and the cerebrovenous blood temperature is an additional source of information about relative changes of the CBF.

Effect of omental angiogenic lipid factor on revascularization of autotransplanted spleen in dogs.

Since the turn of the century, studies have been carried out showing that the omentum contains a factor which enhances revascularization of ischemic tissues. This study was conducted for a period of 3 months and was designed to evaluate the effect of an omental lipid fraction on neovascularization of autotransplanted spleen chips in dogs. Twelve dogs underwent splenectomy and autotransplantation of 5 splenic chips into an omental pouch. In 4 dogs, the splenic chips were immersed in omental angiogenic lipid factor (OAF), while on another 4 dogs, an intramuscular injection of 4 cm3 of OAF was given each day for 7 days postoperatively. A further 4 dogs were not given any of the above treatments (control group). Serial angiographies and histologic examinations demonstrated better neovascularization and regeneration of the transplanted spleen in the dogs from the immersion plus injection group. These data suggest that the omental lipid fraction contains a factor which induces a better regeneration of splenic transplants.