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Biomedical subjects

T M Krummel

Publications and source records attributed to T M Krummel.

At least 37 records · Page 2Linked to original sources
PubMed1999

Effects of dexamethasone, growth factors, and tracheal ligation on the development of nitrofen-exposed hypoplastic murine fetal lungs in organ culture.

BACKGROUND/PURPOSE: The addition of growth factors EGF (epidermal growth factor) plus TGFbeta1 (transforming growth factor beta1; E + T) or dexamethasone (DEX) to normal murine fetal lungs in culture enhances lung development. In addition, ligation of the airway in lungs in organ culture, enhances lung development. Nitrofen (2,4-dichlorophenyl-p-nitrophenylether) administration to pregnant mice results in pulmonary hypoplasia in the offspring with many similarities to human hypoplastic lung conditions. This study investigates the effects of growth factors, dexamethasone, and airway ligation on the development of hypoplastic fetal murine lungs in whole-organ culture. We hypothesized that E+T, DEX, or airway ligation will enhance the development and maturation of hypoplastic murine fetal lungs in vitro. METHODS: Time-dated pregnant CD-1 mice were given nitrofen, 25 mg, intragastrically at gestational day (Gd) 8. The dams were killed on Gd 14, and the fetuses were removed. The hypoplastic fetal lungs were excised, and the tracheae were transected. The lungs were cultured in serum-free BGJb media in the presence or absence of E+T (10 ng/mL + 2 ng/mL, respectively) or DEX (10 nmol/L). Some lungs were cultured for 7 days with the tracheae ligated. RESULTS: Gross morphology under a dissecting stereomicroscope showed that the lungs were larger after E+T, DEX, or tracheal ligation. Histologically, the untreated lungs had progressed from the pseudoglandular stage to a canalicular-like stage with poorly differentiated airways. The E+T-treated lungs had better developed airway branching and small acini; however, thick mesenchyme persisted. The ligated lungs had well-developed airway branching and acinar structures. After DEX treatment the lungs were most developed with very well defined airway branching and expanded acinar structures; however, there was no secondary septation. Ultrastructurally, the hypoplastic lungs at Gd 14 and after 7 days in culture had no glycogen in their epithelial cells, no defined acinar formation, and had damaged mitochondria. The E+T-treated or tracheally ligated lungs had abundant type II cells, secreted lamellar bodies (LBs), and showed infrequent tubular myelin. Mitochondrial damage was noted in these lungs as in the untreated lungs. DEX-treated hypoplastic lungs showed large acini. The acinar walls were thick; however, they had type II cells with abundant LBs and intact mitochondria. The airways were noted to have differentiated cell types. Surfactant secretions in acinar spaces showed tubular myelin structures. CONCLUSIONS: E+T, tracheal ligation, or DEX accelerates lung development and maturation of hypoplastic fetal murine lungs compared with untreated controls. DEX had a greater effect with special reference to repair of mitochondrial damage. DEX not only accelerated lung development, but it may have reversed some of the effects nitrofen.

Animals↗
PubMed1999

Postnatal pulmonary hypertension after repair of congenital diaphragmatic hernia: predicting risk and outcome.

BACKGROUND: Pulmonary hypertension (PH) after congenital diaphragmatic hernia (CDH) repair remains a significant cause of morbidity and mortality. Although treatment advances have improved overall survival, a new cohort of patients is surviving with PH beyond the postnatal period. Because the clinical entity of postnatal persistent pulmonary hypertension (PPHTN) in CDH patients has not been published, the authors undertook a retrospective study of our neonatal CDH experience to characterize this group of infants. METHODS: Charts of all infants with CDH treated at this institution from January 1991 to June 1997 were reviewed (n = 51). Persistent pulmonary hypertension by echocardiographic (Echo) measurements at the time of discharge identified PPHTN patients. Control survivors had normal pulmonary artery pressures at discharge. Physiological parameters and the results of therapeutic interventions were analyzed to predict PPHTN. RESULTS: Seven infants (four boys, three girls) had PPHTN at discharge. Significant differences with the control group were noted in length of stay, duration of intubation, and duration of nitric oxide therapy. Extracorporeal membrane oxygenation (ECMO) duration was not significantly different between the groups. By 12 months of age, PPHTN resolved in six patients (87%), and one died at 13 months. Regardless of therapy, two parameters showed 100% positive predictive value for identifying patients with PPHTN (P < .001): an Echo demonstrating PH at 2 months of age or continued oxygen requirement at 3 months. Oxygen requirement at 2 months had a 67% predictive value of PPHTN. CONCLUSIONS: With current treatment strategies for CDH, infants can survive with persistent pulmonary hypertension beyond the newborn period. The long-term survival rate is excellent, and normalization of pulmonary artery pressures can be expected. PPHTN can be predicted in those infants with Echo-defined pulmonary hypertension at 2 months.

Chi-Square Distribution↗
PubMed1999

Measuring and developing suturing technique with a virtual reality surgical simulator.

BACKGROUND: We have developed an interactive virtual reality (VR) surgical simulator for the training and assessment of suturing technique. The surgical simulator is comprised of surgical tools with force feedback, a 3-dimensional graphics visual display of the simulated surgical field, physics-based computer simulations of the tissues and tools, and software to measure and evaluate the trainee's performance. STUDY DESIGN: This study uses the simulator to measure and compare the skills of 8 experienced vascular surgeons versus 12 medical students when performing a virtual reality suturing task. Eight parameters of the suturing task were measured: total tissue damage, accuracy of needle puncture, peak tissue tearing force, time to complete the task, damage to the surface of the tissue, angular error in needle technique, total distance traveled by the tool tip, and a measure of overall error. Three test conditions (dominant hand, nondominant hand, and 3-dimensional needle guide) were tested. Statistical significance was defined as a univariate two-sided p value < or = 0.05. RESULTS: The surgeons' average performance was significantly better than the students' average performance for three of the measured parameters (total tissue damage, time to complete the task, and total distance traveled by the tool tip) for each of the test conditions. For the test condition most similar to surgery (using the dominant hand to suture) one additional parameter was also significantly different (the measure of overall error). The medical students showed improvements for 6 of the 7 parameters for which the users received feedback during the training process. The surgeons also had significant improvement for 4 of the 7 parameters. The students had a larger improvement than the surgeons for 6 of the parameters, but these differences were not statistically significant. CONCLUSIONS: Data indicate differences between surgeon and nonsurgeon performance and in improvement in performance with training. One possible explanation for the superior performance of the surgeons is that their suturing skills applied well to the simulated suturing task. Additional research is required to confirm or deny the similarity between actual and simulated surgical tasks and the relevance of virtual reality surgical simulation to surgical skill assessment and training.

Computer Simulation↗
PubMed1999

Tactile feedback is present during minimally invasive surgery.

BACKGROUND: The applications of minimally invasive surgery (MIS) and laparoscopy are rapidly expanding. Despite this expansion, our understanding of the importance of haptic feedback during laparoscopic surgery is incomplete. Although many surgeons believe that the use of minimally invasive techniques eliminates force feedback and tactile sensation (haptics), the importance of haptics in MIS has not been fully evaluated. There is considerable interest in the development of simulators for MIS even though the importance of force feedback remains poorly understood. This study was designed to determine the ability of experienced surgeons to interpret haptic feedback with respect to texture, shape, and consistency of an object. STUDY DESIGN: A randomized, single-blinded study was designed. Twenty surgeons were presented objects in a random order, with participants blinded as to their identity. Inspection by direct palpation, conventional instruments, and laparoscopic instruments was performed on all objects. Statistic analysis of the data was performed using chi-square analysis and, when appropriate, a Fischer exact probability test. RESULTS: Direct palpation was associated with the highest accuracy for shape identification and was superior to both conventional instruments (p < 0.001) and laparoscopic instruments (p<0.001). Fine texture analysis with either a conventional instrument or a laparoscopic instrument was superior to direct palpation (p < 0.05). Finally, the three methods of analysis were comparable for consistency analysis. CONCLUSIONS: These data indicate that laparoscopic instruments do, in fact, provide surgeons with haptic feedback. Interpretation of the texture, shape, and consistency of objects can be performed. In some situations, laparoscopic instruments appear to amplify the haptic information available. Our ongoing work is directed at further defining force interactions.

Adult↗
PubMed1999

Differences between scar and dermal cultured fibroblasts derived from a patient with recurrent abdominal incision wound herniation.

Fibroblasts were derived from dermis and scar of a 47-year-old white man with a recurrent incisional hernia as a result of fractured ribs. The scar was thin and stretched, suggesting a defect in the maturation of granulation tissue. After surgical repair, biopsy specimens of discarded scar and skin were used to generate fibroblast cell lines. Fibroblasts maintained in medium containing 10% fetal bovine serum and antibiotic were studied between their third and eighth passage. By phase contrast microscopy, no structural differences were obvious, but it was noted that to pass scar fibroblasts, a more aggressive trypsin regimen was required. Immunohistologic and Western blot analysis of patient scar fibroblasts showed (1) more a smooth muscle actin within stress fibers, (2) increased expression of the vitronectin integrin receptor alpha(v) (CD 51), and (3) reduced expression of the collagen integrin receptor alpha2 (CD 49b). The expression of vinculin from focal adhesions or a tubulin from microtubules was the same among cell lines. Contractions of scar and dermal fibroblast-populated collagen lattice were compared. At 24 hours, contractions were 69 percent with newborn fibroblasts (normal); 68 percent for patient dermal fibroblasts; and only 48 percent for patient scar fibroblasts. The retarded contraction of scar fibroblast-populated collagen lattice was significant (p > or = 0.002). Myosin ATPase activity, critical for lattice contraction, and cell migration were equivalent among all cell lines. A plausible mechanism for the retardation of scar lattice contraction is disruption of fibroblasts and collagen interactions, for which the attachment of cells to collagen is altered. It is proposed that either the decrease in the expression of collagen integrin receptor alpha2 (CD 49b), an increase in the expression of the vitronectin receptor alpha(v) (CD 51), or a combination of both is responsible for disruption of collagen fibroblast interactions.

Actins↗
PubMed1999

Virtual reality and women's health: a breast biopsy system.

Minimally invasive procedures are becoming much more common in surgical practice because of the many advantages for patient comfort and convenience, and improved surgical access. However some of the major problems leading to occasional surgical errors with this minimal access method are restricted vision, limited sense of touch, difficulties in identification in 3D space of the position of the instrument tips, and their handling during delicate, short-distance movements toward the surgical target area. These factors emphasize the need for computer simulated training in surgical manipulations and procedures in preparation for conducting them in patients. The key new feature of our proof-of-concept training simulator is a preventive mechanism that serves at least two functions. As the surgical target (or a critical structure) is approached, a haptically generated preventive force forewarns the surgeon, making it possible to abort those maneuvers that may lead to adverse results. By announcing a potential collision of a virtual instrument tip with a surgical target, the time used for searching for the target is shortened, and the haptic signal minimizes the potential of tissue damage. This real-time, interactive, virtual reality based, haptic breast biopsy-training simulation is a PC/NT based multitasking, multithreading system. It is based upon an advanced force feedback device. The system monitors and indirectly guides the surgeon's movements, while providing high fidelity visual and force feedback cues as the area of surgical interest is approached. Our first application is with human breast.

Algorithms↗
PubMed1999

Defining the role of haptic feedback in minimally invasive surgery.

INTRODUCTION: The applications of Minimally Invasive Surgery (MIS) and Laparoscopy are rapidly expanding. Despite this expansion, the technology related to our understanding of the importance of haptic feedback related to laparoscopic surgery remains in its infancy. While many surgeons feel that the use of minimally invasive techniques eliminates force feedback and tactile sensation, the importance of haptics in MIS has not been fully evaluated. Moreover, there is considerable interest in the development of haptic simulators for MIS even though the importance of force feedback remains poorly understood. This study was designed to determine the ability of novice surgeons to interpret haptic feedback with respect to texture, shape and consistency of an object. METHOD: Subjects were presented objects in a random order and participants were blinded as to their identity. Inspection by direct palpation, palpation with conventional instruments, and palpation with laparoscopic instruments was performed on all objects. Statistical analysis of the data was performed using a Fischer exact probability test. RESULTS: Direct palpation provided the greatest degree of haptic feedback and was associated with the highest accuracy for texture discrimination, shape discrimination, and consistency discrimination. A significant decrease in the ability to identify shapes was noted with both CI and LI. A significant decrease in the ability to differentiate consistency was noted for LI only. When comparing palpation with conventional instruments to palpation with laparoscopic instruments, there was no significant difference in shape or texture discrimination. There was, however, a significant decrease in consistency discrimination. CONCLUSION: This data indicates that laparoscopic instruments do in fact provide the surgeon with haptic feedback. While the instruments change the information available to the surgeon, interpretation of the texture, shape and consistency of objects can be performed. Our ongoing work is directed at further defining force interactions. Through the use of force feedback impulse devices in VR simulators, one should be able to create a more realistic theatre in which the novice surgeon can learn operative skills that will readily translate into the operating room.

Feedback↗
PubMed1999

Simulation and virtual reality for surgical education.

Rapid advancements in technology have dramatically changed the way our daily activities are conducted. In the practice of medicine and surgery, technological advances over the past few decades have had an enormous impact on the diagnosis and treatment of disease. In contrast, our methods of teaching surgeons to perform operations remain mired in the 100 year old Halstedian apprenticeship model. In this system, surgeons often learn to operate based on the principle of "see one, do one, teach one." Educational opportunities are largely dependent on chance as a patient with a particular disease pattern must present to the surgeon in order to achieve specific educational goals. Live patients are often used as the initial "practice session" for the learning surgeon in this model of education.

Journal Article↗
PubMed1998

Influence of epidermal growth factor and transforming growth factor beta-1 on patterns of fetal mouse lung branching morphogenesis in organ culture.

Transforming growth factor-beta (TGF-beta), a potent inhibitor of epithelial cell proliferation, and epidermal growth factor (EGF), a mitogenic polypeptide that binds to cell surface receptors, are important regulators of cell differentiation; however, their distinct role(s) in lung development and their mechanisms of action are not well understood. We evaluated the effects of these factors on lung morphogenesis in murine fetal lungs at gestational day 14 (time:zero) and again after 7 days in culture. Baseline controls were cultured after tracheal transection in supplemented BGJb medium, and other tracheally transected lungs were cultured following addition of EGF (10 ng/ml BGJb), TGF-beta1 (2 ng/ml BFJb), or with both in combination added to the medium. The control lungs in culture had poorly developed airways and an absence of defined acinar structures. The addition of EGF resulted in hyperplasia of primary airways with stunted outgrowths, monopodial branching, and absence of distinct acinar structures. Addition of TGF-beta1 alone, led to significant elongation of primary airways, without normal airway branching; however, terminal dipodial branching was seen and the prospective pulmonary acini were well defined. Combination of these growth factors (GF) resulted in a more normal branching pattern and differentiation, suggesting their epigenetic role in lung morphogenesis and mutual interactive mechanisms that regulate lung development. These lungs had more abundant and larger lamellar bodies than those after other treatments. Control lungs remained immature with prominent glycogen aggregates with occasional dense lamellar bodies. The total protein and DNA contents were highest with EGF treatment, followed by combination treatment; these observations were supported by immunohistochemical localization of proliferating cell nuclear antigen, an indication of the proliferative state of tissues. All the surfactant proteins were relatively unaltered and their messages were up-regulated for SP-A, but down-regulated for SP-B and SP-C in the lungs treated with growth factors. In conclusion, we have demonstrated enhanced biochemical and structural development of lungs treated in vitro with GF, and propose that further research in this area may lead to therapeutic uses of GF alone or in combination with other agents for the treatment of newborn respiratory distress due to lung immaturity or hypoplastic lung development.

Animals↗
PubMed1998

Differential gene expression at gestational days 14 and 16 in normal and nitrogen-induced hypoplastic murine fetal lungs with coexistent diaphragmatic hernia.

The purpose of this study was to identify differentially expressed genes in normal and nitrofen-induced hypoplastic lungs in fetal mice. Such genes may play a role in the regulation of lung development. CD-1 pregnant dams were gavaged with 25 mg of nitrofen on gestational day (Gd) 8 to induce pulmonary hypoplasia and diaphragmatic hernia (DH). Normal and nitrofen-treated fetuses were removed on Gd 14 and Gd 16. Lungs were examined in all nitrofen-exposed fetuses and only those that had developed severely hypoplastic lungs with coexistent diaphragmatic hernia were taken for molecular analyses. RNA was extracted from normal and nitrofen-treated lungs, reverse transcribed, and PCR-amplified using 48 combinations of anchor and arbitrary primers for each condition. The resulting cDNAs from normal and hypoplastic lungs were run on 6% polyacrylamide differential display gels. In Gd 14 lungs, we observed 10 differentially expressed cDNA bands, of which 6 were identified to be inhibited and 4 were reduced in the hypoplastic lungs compared to normal fetal lungs. From the Gd 16 lungs, a total of 29 differentially expressed cDNA bands were found, of which 11 were reduced, 4 were inhibited, 11 were enhanced, and 3 were induced in the hypoplastic compared to the normal lungs. All 39 differentially expressed cDNAs were cloned, sequenced, and identified through BLAST searches. Among the sequences that were identified, results were as follows: 1) Hypoplastic Gd 14 lungs had two unknown cDNA sequences with reduced/inhibited expressions, whereas one was a known sequence having 77% similarity with a promoter region regulating various cytokines such as IL-1, IL-2, and IL-11. The expression of this sequence was inhibited in the hypoplastic lungs. This sequence also had similarity to lipid-binding proteins. 2) On Gd 16, hypoplastic lungs had one cDNA sequence with reduced expression which had 82% similarity with thyroid hormone receptor gene exon 1 and two other cDNA sequences with enhanced expressions. One of these enhanced cDNA sequences in hypoplastic lungs had 98% similarity with the fibroblast growth factor receptor-3 gene, and the other was an unknown sequence. Northern blot hybridizations were performed to confirm the differential expression of the two sequences of interest, which were identified as thyroid hormone receptor and fibroblast growth factor (FGF) receptor-3. Overall, out of a total of 39 RT-PCR products (i.e., cDNAs), the abundance of which was altered by nitrofen, 6 were found to be homologous to sequences in Gen Bank through BLAST searches. These 6 sequences became the products of interest, and 3 of these 6 products were similar to previously identified genes. Our results may shed some light on regulatory aspects of lung development and open avenues for treatment of hypoplastic lungs and other respiratory problems in human neonates.

Animals↗
PubMed1998

Inhibiting the differentiation of myocardiocytes by hyaluronic acid.

BACKGROUND: In vitro experimentation found that wounded midgestation fetal mouse hearts heal scarlessly. Scarless repair occurs in an environment enriched in hyaluronic acid (HA), while in the absence of HA and the inclusion of hyaluronidase (HAdase), repair by scarring occurs. Excess HA downregulates the expression of the specific HA receptor, RHAMM (receptor for HA-mediated motility). The expression of RHAMM and the migration of cardiac cells from fetal heart explants were investigated in the presence of excess HA and added HAdase. METHOD: Hearts from Gestational Day 15 fetal mice (term = 20) were cut into four fragments, established as explant cultures, and assigned to one of three treatment groups: 400 micrograms/ml HA, 50 U/ml HAdase, or saline. Cellular outgrow was recorded at Day 7. The character of the migrating cells (fibroblast-like or myocardiocyte) was determined by immunostaining for filamentous actin (f-actin, microfilaments) or desmin (intermediate filaments). The expression of RHAMM was documented also. RESULTS: The inclusions of HA stimulated cell migration and proliferation, perpetuated cells as immature myocardiocytes, and blocked the expression of RHAMM. The inclusion of HAdase limited cell migration and proliferation, promoted the differentiation of cells into myocardiocytes, and increased the number of cells expressing RHAMM. CONCLUSION: Increased concentrations of HA promoted the proliferation and migration of an immature population of myocardiocytes. On the other hand the inclusion of HAdase inhibits the migration and proliferation of cells and promotes the appearance of myocardiocytes with a fibroblast-like morphology. The speculation is that excess HA may promote proliferation and migration of immature myocardiocytes into a heart defect, leading to replacement of lost myocardium with contractile tissue rather than dysfunctional scar.

Animals↗
PubMed1998

Esophageal/pyloric ligation enhances development of the murine fetal stomach in organ culture.

PURPOSE: The authors hypothesized that increased intraluminal pressure in the fetal stomach would enhance development in a murine organ culture model. METHODS: Gestation day 14 (Gd14) fetal stomachs from time-dated pregnant CD-1 mice (term, 20 days) were maintained in organ culture for 7 days. Some stomachs were ligated at the gastroesophageal (GE) and pyloroduodenal (PD) junctions. Others were left unligated. Gd14, Gd16, and Gd18 stomachs were taken as well to compare organogenesis in vivo. Tissues were processed for histological, morphometric, and immunohistochemical analysis, as well as total protein and DNA determination. RESULTS: The ligated stomachs were visibly distended compared with unligated stomachs in organ culture after 7 days. The length and width of the 7-day in vitro ligated stomachs were significantly increased compared with unligated (2.97+/-0.04 mm v 2.48+/-0.05 mm and 2.14+/-0.04 mm v 1.57+/-0.08 mm, respectively, P < .05). Mucosal epithelial cells showed nuclear polarization, and there was a distinct outer muscle layer in the ligated stomachs, but not in the unligated stomachs, which demonstrated pseudostratified epithelial cells in the mucosa. The ligated stomachs had increased in mucosal thickness compared with unligated (31.4+/-1.3 microm vs 24.9+/-0.9 microm, p < 0.05). The ligated stomachs also had significantly increased protein and DNA content when compared with unligated stomachs (65.8+/-3.1 microg and 23.3+/-1.2 microg v 55.0+/-2.7 microg and 19.0+/-1.2 microg, respectively, P < .05). However, there were no significant differences noted between the protein to DNA ratios. Immunohistochemical staining for proliferating cell nuclear antigen (PCNA), a marker for cell proliferation, demonstrated increased proliferative activity of the mucosal epithelial cells in the ligated stomachs. CONCLUSIONS: Esophageal and pyloric ligation enhanced the development of the fetal stomach in vitro in comparison with unligated stomachs cultured under similar conditions. Developmental characteristics of the ligated stomachs paralleled that of Gd16 stomachs in vivo.

Animals↗
PubMed1998

Hyaluronan induces scarless repair in mouse limb organ culture.

BACKGROUND/PURPOSE: Wounded fetal mouse limbs harvested from two distinct time points in gestation heal differently in organ culture. The healing of a gestational day 14 limb is by scarless repair, whereas gestational day 18 (gd 18) limbs heal by scarring. The persistence of elevated levels of hyaluronic acid (HA) is a major difference in the extracellular matrix of scarless repair. The purpose of this study was to demonstrate that chronic additions of HA to incisional wounds of gd 18 limbs induces scarless repair. METHODS: Time-dated pregnant CD-1 mice (term, 20 days) were killed on gestational day 18 and fetuses were harvested via laparotomy. A through and through stab wound was made in each forelimb with a 1-mm microscapel, and the wound was closed with a single 10-0 nylon suture. The forelimbs were amputated at the level of the shoulder and placed in organ culture. Daily medium changes with 1 mL of BGJb (devoid of serum) were made. Half the cultures received 10 microL of HA (4 mg/mL) directly to the wound site with each medium change. The other half of the cultures received 10 microL of phosphate-buffered saline (PBS-control). At day 7, the limbs were harvested, fixed in methyl Carnoys solution, paraffin embedded, and 5-microm serial sections cut. The sections were stained with H&E or Sirius red/fast green. The sections were viewed in a blinded fashion by two observers. Suture defined the wound site, and the sections were graded for healing by scarring. RESULTS: Minimal limb growth occurred in both control and HA-treated limbs. Grossly, both control and treated limbs healed incisional wounds by 7 days in culture. Limbs from both treatment and control groups showed viability by microscopic analysis. The limbs treated with HA had no appreciable scar morphologically in sections in which epithelial dimpling and suture were evident. The orientation of the collagen fiber bundles in the control wounds were in parallel arrays perpendicular to the incision. The orientation of the collagen fiber bundles in the HA-treated limbs had a basket weave pattern that was indistinguishable from unwounded dermis. The direct repeated additions of HA to healing organ cultured limb explants of gestational day 18 fetal mice promoted scarless repair. CONCLUSIONS: This result demonstrates that chronic elevation of HA in the microenvironment of a wound affects healing by promoting the deposition of a more dermal-like connective tissue matrix in the wound site. The maintenance of elevated levels of HA could have utility in the clinical setting to improve the organization of connective tissue, leading to the reduction of scar complications.

Animals↗
PubMed1998

Growth factors and dexamethasone regulate Hoxb5 protein in cultured murine fetal lungs.

Studies on lung morphogenesis have indicated a role of homeobox (Hox) genes in the regulation of lung development. In the present study, we attempted to modulate the synthesis of Hoxb5 protein in cultured murine fetal lungs after mechanical or chemical stimuli. Murine fetuses at gestational day 14 (GD14) were removed from pregnant CD-1 mice, and lungs were excised and cultured for 7 days in BGJb media. The experimental groups were 1) untreated, unligated; 2) tracheal ligation; 3) supplemented media with either epidermal growth factor (EGF; 10 ng/ml), transforming growth factor (TGF)-beta 1 (2 ng/ml), dexamethasone (10 nM), EGF + TGF-beta 1, or EGF + TGF-beta 1 + dexamethasone. After 3 or 7 days, the cultured lungs were compared with in vivo lungs. Immunoblotting signals at 3 days in culture were stronger than those at 7 days. Western blot analyses showed that ligation, EGF, TGF-beta 1, and EGF + TGF-beta 1 downregulated Hoxb5 protein to approximately 20-70% of Hoxb5 protein levels in unligated, untreated cultured lungs. Furthermore, dexamethasone alone or in combination with EGF and TGF-beta 1 downregulated Hoxb5 protein by > 90% (P < 0.05) signal strength, similar to that seen in GD19 or in neonatal lungs. Immunostaining showed that Hoxb5 protein was expressed strongly in the lung mesenchyme at early stages in gestation. However, by GD19 and in neonates, it was present only in specific epithelial cells. A persistent level of Hoxb5 protein in the mesenchyme after EGF or TGF-beta 1 treatments or tracheal ligation was noted. Hoxb5 protein was significantly downregulated by EGF + TGF-beta 1, and it was least in lungs after dexamethasone or EGF + TGF-beta 1 + dexamethasone treatment. The decrease in Hoxb5 protein was significant only in the groups with dexamethasone added to the media. Thus immunostaining results parallel those of immunoblotting. The degree of Hoxb5 downregulation by dexamethasone or EGF + TGF-beta 1 + dexamethasone was similar to that seen in vivo in very late gestation, which correlated to the advancing structural development of the lung.

Animals↗
PubMed1998

Colovesical fistula resulting from a perforated colonic duplication.

Colovesical fistulas in children are most often associated with high anorectal imperforations. Acquired enterovesical fistulas in children only rarely have been reported as a consequence of an inflammatory process. We present a case of an acquired colovesical fistula formed by the erosion of an abscess at the distal end of a colonic duplication in a child who presented with fever of unknown origin.

Abdominal Abscess↗