Ueli Moehrlen

Impact of carbon dioxide versus air pneumoperitoneum on peritoneal cell migration and cell fate

BackgroundPostoperative systemic immune function is suppressed after open abdominal surgery, as compared with that after minimally invasive abdominal surgery. As a first line of defense, peritoneal macrophages (PMo) and polymorphonuclear neutrophil granulocytes (PMNs) are of primary importance in protecting the body from microorganisms. Previous studies have shown changes in these cell populations over time after open versus laparoscopic surgery. This study aimed to investigate the dynamics of cell recruitment and clearance of peritoneal cells.MethodsFemale NMRI mice (33 ± 2 g) were randomly assigned to carbon dioxide (CO2) or air insufflation. Intravasal cells with phagocytic capabilities were selectively stained by intravenous injection of the fluorescent dye PKH26 24 h before surgery. Gas was insufflated into the peritoneal cavity through a catheter, and the pneumoperitoneum was maintained for 30 min. Peritoneal lavage was performed 1, 3, 8, or 24 h after surgery. Apoptotic cells were assessed by flow cytometry using a general caspase substrate.ResultsThe total peritoneal cell count did not differ between groups. The PKH26-positive PMo level was significantly increased after CO2, as compared with air, at 1 h and 24 h. The ratio of apoptotic PMo did not differ between the groups. In the peritoneal lavage, polymorphonuclear leukocytes (PMNs) were tripled in the air group, as compared with the CO2 group, whereas the ratio of apoptotic PMNs was significantly decreased. There was a higher fraction of PKH26-positive PMNs after air exposure, as compared with that after CO2.ConclusionsAir exposure triggered a higher transmigration rate of PMNs from the blood compartment into the peritoneal cavity and decreased PMN apoptosis, as compared with CO2. The lower proportion of PKH26-positive peritoneal macrophages in the air group might have been attributable to a higher inflammatory stimulation than in the CO2 group, leading to increased emigration of PMo to draining lymph nodes. All the findings underscore a complex cell-specific regulation of cell recruitment and clearance in the peritoneal compartment.

Fetal surgery for myelomeningocele is effective: a critical look at the whys

Formerly, the disastrous cluster of neurologic deficits and associated neurogenic problems in patients with myelomeningocele (MMC) was generally thought to solely result from the primary malformation, i.e., failure of neurulation. Today, however, there is no doubt that a dimensional additional pathogenic mechanism exists. Most likely, it contributes much more to loss of neurologic function than non-neurulation does. Today, there is a large body of compelling experimental and clinical evidence confirming that the exposed part of the non-neurulated spinal cord is progressively destroyed during gestation, particularly so in the third trimester. These considerations gave rise to the two-hit-pathogenesis of MMC with non-neurulation being the first and consecutive in utero acquired neural tissue destruction being the second hit. This novel pathophysiologic understanding has obviously triggered the question whether the serious and irreversible functional loss caused by the second hit could not be prevented or, at least, significantly alleviated by timely protecting the exposed spinal cord segments, i.e., by early in utero repair of the MMC lesion. Based on this intriguing hypothesis and the above-mentioned data, human fetal surgery for MMC was born in the late nineties of the last century and has made its way to become a novel standard of care, particularly after the so-called “MOMS Trial”. This trial, published in the New England Journal of Medicine, has indisputably shown that overall, open prenatal repair is distinctly better than postnatal care alone. Finally, a number of important other topics deserve being mentioned, including the necessity to work on the up till now immature endoscopic fetal repair technique and the need for concentration of these extremely challenging cases to a small number of really qualified fetal surgery centers worldwide. In conclusion, despite the fact that in utero repair of MMC is not a complete cure and not free of risk for both mother and fetus, current data clearly demonstrate that open fetal–maternal surgery is to be recommended as novel standard of care when pregnancy is to be continued and when respective criteria for the intervention before birth are met. Undoubtedly, it is imperative to inform expecting mothers about the option of prenatal surgery once their fetus is diagnosed with open spina bifida.

Early peritoneal macrophage function after laparoscopic surgery compared with laparotomy in a mouse model

BackgroundThe authors previously demonstrated postoperative preservation of the immune function measured by delayed-type skin reaction and tumor growth after laparoscopic surgery, as compared with laparotomy. For further elucidation of the origin of the demonstrated immune preservation, peritoneal macrophage (PMo) function was investigated 1 h after different surgical procedures.MethodsFemale NMRI mice were divided into five groups: anesthesia only, abdominal skin incision, laparotomy, peritoneal carbon dioxide (CO2) insufflation, and peritoneal air insufflation. Escherichia Coli phagocytosis, tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), and interleukin-10 (IL-10) release of isolated PMo were investigated.ResultsAll invasive interventions reduced the PMo phagocytosis by factors of approximately 2 to 4.7, as compared with the sham control group. Spontaneous ex vivo TNF-α release was significantly increased whenever the abdominal cavity was exposed to ambient air. The macrophage’s ability to release TNF-α after E. coli exposure was diminished in the abdominal air exposure groups, as compared with the CO2 insufflation group.ConclusionReduced phagocytosis 1 h after surgical interventions suggests a contribution of PMo to the altered immune function. When exposed to CO2, PMo show a decreased basal TNF-α release. However, PMo also show an increased TNF-α release after a second immune stimulation (E. coli), suggesting a greater competency of interaction in an immune defense reaction after CO2 exposure.

No transuterine migration of fertilised ova after unilateral embryo transfer in mice

Transuterine migration is the passage of fertilised ova from one uterine horn into the other. The phenomenon has been described for animals of different species with a bicornuate type of uterus. Whether or not it occurs in rodents is questionable, but could have an impact on the way embryo transfers are carried out, i.e. unilaterally or bilaterally. The aim of this study was to examine the occurrence of transuterine migrations in nulliparous and multiparous mice after unilateral embryo transfer. Sixteen two-cell embryos were transferred into either the left or the right oviduct of mice with different genetic origin. With the exception of one reabsorption site in the opposite uterine horn, we never found evidence for the occurrence of transuterine migration. This is also true for embryo transfers carried out after parturition of the surrogate mother. Even the successful development of up to 13 embryos in one uterine horn did not result in transmigration but may be the reason for the widespread assumption that transuterine migration occurs after unilateral embryo transfers. The separation of the uterine body and the prevaginal portion of the uterine cervix into two canals by a septum seems to be the main reason for the absence of successful transuterine migration in mice.

Incidence of metachronous contralateral inguinal hernias in children following unilateral repair — A meta-analysis of prospective studies

PURPOSE The objective of this review was to systematically evaluate the incidence of a metachronous contralateral inguinal hernia (MCIH) in children with unilateral inguinal hernia and therefore to propose or to reject routine contralateral groin exploration. METHODS Electronic searches restricted to prospective studies with a minimal follow-up of 1year included MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. RESULTS Six studies involving 1669 children were included. Overall MCIH was 6% (95% CI from 4% to 8%). The odds for MCIH development were significantly larger in children with an initial left-sided hernia (OR 2.66 with 95% CI from 1.56 to 4.53) and in children with open contralateral processus vaginalis (CPV) (OR 4.17 with 95% CI from 1.25 to 13.9). CONCLUSIONS The overall incidence of MCIH following unilateral inguinal hernia repair in children is 6%. Initial left-sided hernia (8.5%) and open CPV (13.8%) are risk factors for MCIH development. Female gender (8.2%) and younger age (<1year) (6.9%) non-significantly increase the risk of MCIH.

Premiere use of Integra™ artificial skin to close an extensive fetal skin defect during open in utero repair of myelomeningocele.

BackgroundThere are fetuses demonstrating very large myelomeningocele lesion which can not be covered with autochothonous skin.Material and MethodsWe use Integra™ artifical skin for intrauterine coverage of the back lesion. A reverse latissimus dorsi flap was used postnataly to reinforce the repair site.ConclusionIntegra™ appears to be a suitable coverage for large soft tissue defects in utero. Moreover, a postnatal reverse latissimus dorsi flap appears to markedly strengthen tissue coverage over a spinal cord rescued in utero.

Experimental tissue engineering of fetal skin.

PurposeIn some human fetuses undergoing prenatal spina bifida repair, the skin defect is too large for primary closure. The aim of this study was to engineer an autologous fetal skin analogue suitable for in utero skin reconstruction during spina bifida repair.MethodsKeratinocytes (KC) and fibroblasts (FB) isolated from skin biopsies of 90-day-old sheep fetuses were cultured. Thereafter, plastically compressed collagen hydrogels and fibrin gels containing FB were prepared. KC were seeded onto these dermal constructs and allowed to proliferate using different culture media. Constructs were analyzed histologically and by immunohistochemistry and compared to normal ovine fetal skin.ResultsDevelopment of a stratified epidermis covering the entire surface of the collagen gel was observed. The number of KC layers and degree of organization was dependent on the cell culture media used. The collagen hydrogels exhibited a strong tendency to shrink after eight to ten days of culture in vitro. On fibrin gels, we did not observe the formation of a physiologically organized epidermis.ConclusionCollagen-gel-based ovine fetal cell-derived skin analogues with near normal anatomy can be engineered in vitro and may be suitable for autologous fetal transplantation.

Left-sided mouse intubation: description and evaluation

ABSTRACT A method of left main bronchus intubation was developed based on a wire guide–based microscopic endotrachael mouse intubation technique. The authors used a 22 G × 1 inch catheter elongated by a 38-mm silicone tube, and a wire guide with a tag to assign the length of the wire completely covered by the silicon tube. The isoflurane-anesthetized mouse was hung perpendicularly with its incisors on a thread and transorally intubated under strict vision with the wire guide tip advanced 3 mm out of the catheter. Then the catheter was advanced about 6 to 8 mm into the trachea. Afterwards the wire guide was redrawn to the level of the catheter tip (blue tag on the wire guide appeared at the upper end of catheter) to prevent injury. Then the neck was pushed into a right lateral flexion with one finger against a foam block fixed on the vertical plate, causing a straight distance between mouth and left main bronchus. This positioning allows to gently advance the catheter into the left main bronchus by another about 20 mm, using the wire guide with its tip just within the tube, to achieve there a wedge position with gentle pressure.The technique had a success rate of more than 80%% in 81 mice weighing 23 to 48 g. It may be of interest for unilateral lung intervention, e.g., with injurious substances or with drugs.

Partial cardiopulmonary bypass in rats using a hollow fibre oxygenator

Despite new minimally invasive techniques, cardiopulmonary bypass (CPB) is still necessary for many major operations in the field of cardiac surgery. Unwanted side effects of CPB are well known but poorly understood. We therefore developed a rodent model to study the pathophysiology of these potential complications. Male Fischer rats were anaesthetized, intubated and ventilated. The carotid artery and jugular vein were cannulated. The blood was actively drained from the venous circulation and further transferred by a miniaturized roller pump to a hollow fibre oxygenator and back to the animal via the carotid artery. The roller pump produces a pulsatile blood flow between 5 and 40 ml/min. The surface of the hollow fibre oxygenator is 0.025 m2. The priming volume (Ringer solution) of the whole system is 12 ml. Animals were catheterized and brought in partial bypass for a mean of 50+/-15 min. Normal cardiac function after successful weaning was confirmed by electrocardiography and blood pressure measurements. This technical study demonstrates the feasibility of a small animal model of CPB. The main improvement over existing techniques is the use of a highly effective hollow fibre oxygenator with a minimized priming volume. Therefore, no additional animals are needed as blood donors.

Trauma mechanisms and injury patterns in pediatric burn patients

The objective of this study was to evaluate the frequency, severity, exact patterns and mechanisms of burn injuries in children. The patient records of children with acute burns admitted to the University Childrens Hospital of Zurich were retrospectively reviewed over an 11year period. The age group with the highest risk, were children under the age of five (69%). Boys were overrepresented in all age groups, but the gender imbalance increased with age. Infants and toddlers were mainly injured by scalds and contact burns. Conversely, almost three quarters of injuries over the age of 9 were caused by flame. The majority of scald injuries was a result of pulling down hot liquids. The typical distribution of this accident scenario involved mainly the face, trunk and arms. More than half of all flame injuries occurred due to fire accelerants. 55% of children were passively involved while other children throwing flammable substances into a fire. Most of these injuries involved the face and arms. This study shows that burn etiology is age dependent. Additionally, our results demonstrate the diversity of burn accidents and their resulting injuries. These findings may help better specify target groups and subjects for prevention.