Fertility preservation in prepubertal girls prior to chemotherapy and radiotherapy--review of the literature.

Significant improvement in the survival rates of children with pediatric cancers has been achieved over the last 25 years, so the number of long-term survivors is increasing and their subsequent quality of life is of increasing importance. One of the most serious side effects of chemotherapy or radiotherapy is damage to the ovarian function, which can lead to loss of fertility. The degree of this damage depends on the substances used, the dose of radiotherapy reaching the ovaries, and the age of the girl at the time of treatment. Up to now, the only established method of fertility preservation has been cryoconservation of fertilized egg cells or embryos, but this is not possible in prepubertal girls because of their sexual immaturity. Removal of ovarian tissue and subsequent cryoconservation with the option of later orthotopic retransplantation is therefore an option to these girls. This method can lead to pregnancy and birth in adult women. Up to now there are no studies about the retransplantation of ovarian tissue which was removed before puberty. Displacement of the ovaries away from the radiation field before radiation to the pelvic area can be considered; however, the data is controversial. One problem in the use of fertility preservation methods in these very young patients is that they undergo procedures which, because of their age, they mostly do not understand and the parents must make a decision based on the assumed later wishes of their daughter.

Analysis of the value of imaging as part of the follow-up of splenic injury in children.

OBJECTIVE: A recent article suggested that routine follow-up imaging is still frequently used in the conservative management of splenic trauma in children. The purpose of this study was to use decision analysis to assess the value of routine imaging as part of the long-term follow-up of splenic injury in children managed nonoperatively. METHODS: A literature review (1970-1999) on the management of blunt splenic trauma in children was performed. Data, including the use of follow-up imaging and the occurrence of delayed splenic rupture and death, on those patients managed nonoperatively were collected. The data were used to construct a decision tree. A Poisson distribution was used to determine the risk of delayed splenic rupture. RESULTS: Information was extracted from 26 cohort studies. Nineteen of these studies were retrospective and six were prospective. One study had both retrospective and prospective arms. The study population consisted of 1,083 children. Of these patients, 920 (85 %) underwent routine follow-up imaging (US, CT, or scintigraphy). Follow-up imaging was either not performed or selectively performed in 163 patients (15 %). No cases of post-discharge splenic rupture or death were encountered in any of these groups. The maximum risk of delayed splenic rupture in the entire group was 0.3 % (0-3.7 cases). CONCLUSION: The risk of delayed splenic rupture following blunt injury in children is very low, and is apparently unaffected by imaging protocols. No deaths, even in cases of delayed presentation, were identified in our study. These findings do not support the use of routine follow-up imaging of children with blunt splenic trauma.

EDTA-induced self-assembly of cationic lipid-DNA multilayers near a monolayer-covered air-water interface.

The presence of EDTA in the suspending buffer can induce the formation of multilayer structures from a mixture of the cationic lipid 3beta[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol and the zwitterionic 'helper' lipid 1, 2-dimyristoyl-sn-glycero-3-phosphocholine with DNA. The resulting structures consist of stacks of alternating sheets of lipid bilayer with intercalated DNA. In the absence of EDTA, only a single layer of DNA adsorbs to the lipid membrane. The buffer composition therefore influences the morphology of the lipid-aggregate/DNA assembly, which was not known to date.

Lipid-DNA complex formation: reorganization and rupture of lipid vesicles in the presence of DNA as observed by cryoelectron microscopy.

Cryoelectron microscopy has been used to study the reorganization of unilamellar cationic lipid vesicles upon the addition of DNA. Unilamellar DNA-coated vesicles, as well as multilamellar DNA lipid complexes, could be observed. Also, DNA induced fusion of unilamellar vesicles was found. DNA appears to adsorb to the oppositely charged lipid bilayer in a monolayer of parallel helices and can act as a molecular "glue" enforcing close apposition of neighboring vesicle membranes. In samples with relatively high DNA content, there is evidence for DNA-induced aggregation and flattening of unilamellar vesicles. In these samples, multilamellar complexes are rare and contain only a small number of lamellae. At lower DNA contents, large multilamellar CL-DNA complexes, often with >10 bilayers, are formed. The multilamellar complexes in both types of sample frequently exhibit partially open bilayer segments on their outside surfaces. DNA seems to accumulate or coil near the edges of such unusually terminated membranes. Multilamellar lipid-DNA complexes appear to form by a mechanism that involves the rupture of an approaching vesicle and subsequent adsorption of its membrane to a "template" vesicle or a lipid-DNA complex.

Signals mediating nuclear targeting and their regulation: application in drug delivery.

The recent progress with respect to understanding the signals mediating the transport of proteins in both directions through the NPC, and cellular proteins interacting with these signals to effect the transport process has made possible a number of advances in terms of the use of this information in a clinical setting. In particular, our knowledge of the mechanism of regulation of the process, and of how we may exploit the cellular transport machinery itself in a therapeutic situation, especially where there may be transport pathways specific to particular viruses, has advanced considerably. In this context, this review expounds current understanding of the signals conferring targeting to the nucleus, and their practical and potential use in delivering molecules of interest to the nucleus in a clinical context. It also deals with targeting signals conferring nuclear protein export/ shuttling between nuclear and cytoplasmic compartments as well as with those conferring nuclear or cytoplasmic retention, and with the specific mechanisms regulating the activity of these signals, and in particular those regulating signal-dependent nuclear protein import. Detailed understanding of the processes of signal-mediated nuclear protein import/export and its regulation enables the considered application and optimization of approaches to target molecules of interest, such as plasmid DNA or toxic molecules, efficiently to the nucleus according to need in a clinical or research context, and enhance the expression or efficiency of their action, respectively. The use of nuclear targeting signals in this context is reviewed, and future possibilities in terms of the application of our growing understanding of nuclear transport and its regulation are discussed.

Evidence for three-dimensional interlayer correlations in cationic lipid-DNA complexes as observed by cryo-electron microscopy.

A fingerprint-like pattern across multilamellar, lipid-DNA complexes is attributed to DNA condensed as parallel helices between lipid bilayers. It is argued that the patterning indicates the existence of 3-D correlation forces between DNA-covered bilayers, following the DNA-driven formation of multilamellar liposomes from unilamellar vesicles.