Prospectives In Cleft Lip And Palate Repair

Lhx6 and Lhx8 promote palate development through negative regulation of a cell cycle inhibitor gene, p57Kip2

Cleft palate is a common birth defect in humans. Therefore, understanding the molecular genetics of palate development is important from both scientific and medical perspectives. Lhx6 and Lhx8 encode LIM homeodomain transcription factors, and inactivation of both genes in mice resulted in profound craniofacial defects including cleft secondary palate. The initial outgrowth of the palate was severely impaired in the mutant embryos, due to decreased cell proliferation. Through genome-wide transcriptional profiling, we discovered that p57(Kip2) (Cdkn1c), encoding a cell cycle inhibitor, was up-regulated in the prospective palate of Lhx6(-/-);Lhx8(-/-) mutants. p57(Kip2) has been linked to Beckwith-Wiedemann syndrome and IMAGe syndrome in humans, which are developmental disorders with increased incidents of palate defects among the patients. To determine the molecular mechanism underlying the regulation of p57(Kip2) by the Lhx genes, we combined chromatin immunoprecipitation, in silico search for transcription factor-binding motifs, and in vitro reporter assays with putative cis-regulatory elements. The results of these experiments indicated that LHX6 and LHX8 regulated p57(Kip2) via both direct and indirect mechanisms, with the latter mediated by Forkhead box (FOX) family transcription factors. Together, our findings uncovered a novel connection between the initiation of palate development and a cell cycle inhibitor via LHX. We propose a model in which Lhx6 and Lhx8 negatively regulate p57(Kip2) expression in the prospective palate area to allow adequate levels of cell proliferation and thereby promote normal palate development. This is the first report elucidating a molecular genetic pathway downstream of Lhx in palate development.

Fetal operations in the head and neck area: current state

BACKGROUND

Fetal surgery is defined as prenatal surgical intervention. Such intervention is currently considered in selected cases of fetal malformations that endanger the child's life prenatally or postnatally, such as death or severe impairment.

METHODS

Current indications are reviewed, with special emphasis on success rates and complications, including concomitant ethical problems. Data sources are based on personal experience and medical information systems (especially MEDLINE).

RESULTS AND CONCLUSIONS

In the head and neck areas, especially the upper respiratory tract, such procedures can be indicated in selected cases. They include exposure and temporary obstruction of the fetal trachea to reduce the viscera and to prevent pulmonary hypoplasia in congenital diaphragmatic hernia, prenatal tracheotomy in laryngeal atresia, and intranatal establishment of an airway in airway-obstructing embryonic tumors. The latter surgery can be performed after delivery of the fetal head and neck and before umbilical cord severance. This method ensures oxygenation of the fetus by the maternofetal circulation until completion of the surgical intervention (so called EXIT procedure = Ex-Utero Intrapartum Treatment). The relatively high surgical risk of fetal surgery, in particular postoperative preterm labor, may be reduced by the use of minimally invasive endoscopic techniques. By reducing operative risks even further, prenatal surgical interventions may even be used in nonlethal conditions. Consequently, more diseases of the head and neck area could thus be included in the spectrum of indications, such as prenatal correction of the cleft lip palate. Because fetal wound healing incurs no scarring up to a certain stage in pregnancy, such fetal surgical correction could be a perspective.

Neonatal rat cartilage has the capacity for tissue regeneration

One of the most relevant issues in future medicine is tissue regeneration. Transplantation medicine alone cannot solve the problem of incurable conditions of vital organs. One approach to this might be the replication of the spontaneous regeneration that is found in embryonic/neonatal tissue. In this study, a tissue model for basic investigation of regeneration mechanisms in vivo was established. We demonstrated by histology and immunohistochemical staining for types I and II collagen that neonatal rat cartilage unlike adult cartilage has the capacity for rapid scarfree regeneration after full-thickness incision. The underlying mechanism was identified in the preserved proliferative capacity of neonatal chondrocytes. This in vivo model should prove useful in further studies of the role of cellular (e.g., GA cell cycle regulators) and extracellular (e.g., cytokines) factors in tissue regeneration and wound healing.

Patency and flow characteristics using stapled vascular anastomoses in dialysis grafts

BACKGROUND

Improving patency of hemodialysis grafts is challenging. Vascular stapling creates nonpenetrating anastomoses, possibly decreasing intimal hyperplasia. We investigated patency and flow characteristics of stapled hemodialysis grafts.

METHODS

Eighty-six grafts (41 stapled, 45 sewn) were placed in 84 patients (prospective, randomized). The groups had comparable demographics.

RESULTS

Thirty-six grafts were functioning at the study endpoint. Complications in both groups were similar. The primary patency (stapled, 342 days versus sewn, 382 days; P = 0.67) and secondary patency (stapled, 513 days versus sewn, 507 days; P = 0.76) had no significant differences. Flow characteristics were similar between the groups. Thrombectomies per patient-year were 1.01 for stapled grafts and 1.12 for sewn grafts (not significant). Stapling decreased the average operating time by 4.5 minutes.

CONCLUSIONS

Stapled and sewn anastomoses have similar primary and secondary patency and flow characteristics, with minimal operative time differences. Stapled anastomoses are safe but had no advantage over sewn anastomoses in this study.

Neonatal care of infants with head and neck anomalies

This article reviews the most common serious head and neck congenital anomalies and traumatic injuries that present at or around the time of birth from the perspective of neonatal caregivers. The focus is on the steps necessary to manage these infants in the delivery room and during the first days of life. An organized multidisciplinary team approach is critical to success.

Fetal unilateral cleft lip and palate: detection of enzymic anomalies in the amniotic fluid

Aims of this study were to evaluate whether it is possible to determine, by means of isoelectric focusing, an enzymic differentiation in human amniotic fluid, and whether the onset of fetal cleft lip and palate is accompanied by a pathologic enzymatic differentiation pattern in amniotic fluid. From January of 1993 to June of 1996, amniotic fluid samples from 315 healthy pregnant women (ages 22 to 43 years, mean 37 years; gestational age 14 to 22 weeks, mean 17 weeks) were examined. The normality of all pregnancies was confirmed at birth. Moreover, amniotic fluid samples were examined from three pregnancies (ages 36, 35, and 30 years; gestational ages 16, 18, 24 weeks) with fetal unilateral cleft lip and palate (confirmed at birth), diagnosed by ultrasound. The authors have tested as "metabolic" markers the enzymes lactate dehydrogenase and creatine phosphokinase. For the concentration rates of both the tested enzymes, a statistically significant difference (p = 0.003) was found between amniotic fluid samples obtained from normal and affected pregnancies. These data, in the authors' opinion, corroborate the hypothesis that a local metabolic impairment is somehow involved in the pathogenesis of cleft lip and palate.

Intra-uterine and juxtanatal repair of syndactyly in foetal mice

39 foetal mice with genetic syndactyly were identified in utero at 17 days of gestation, and the right hindfoot extruded through the uterus. The syndactylous digits were separated by simple incisions. In one group (n = 25) digit separation was maintained during wound healing by the interdigital application of a silver microclip. Digit separation was also assessed in a second group of newborn mice less than 24 hours old (juxtanatal population, n = 24). Two foetuses (5%) and six newborns (25%) developed digital necrosis following microclip application. In the remaining microclipped animals (23 intrauterine and 10 juxtanatal), microclip application maintained digit separation, allowing wound healing to occur with epithelialization of the separated digits. No inflammation or scar formation occurred. In the third group (n = 22) without microclip application, the digital skin reapproximated and webbing recurred during wound healing. These studies demonstrate the need to maintain digit separation during wound healing following intra-uterine or juxtanatal syndactyly repair.