Optimal pregnancy outcome in a minimal-stimulation in vitro fertilization program

Delivery of peptide and protein drugs over the blood-brain barrier

Peptide and protein (P/P) drugs have been identified as showing great promises for the treatment of various neurodegenerative diseases. A major challenge in this regard, however, is the delivery of P/P drugs over the blood-brain barrier (BBB). Intense research over the last 25 years has enabled a better understanding of the cellular and molecular transport mechanisms at the BBB, and several strategies for enhanced P/P drug delivery over the BBB have been developed and tested in preclinical and clinical-experimental research. Among them, technology-based approaches (comprising functionalized nanocarriers and liposomes) and pharmacological strategies (such as the use of carrier systems and chimeric peptide technology) appear to be the most promising ones. This review combines a comprehensive overview on the current understanding of the transport mechanisms at the BBB with promising selected strategies published so far that can be applied to facilitate enhanced P/P drug delivery over the BBB.

Comparison of outcomes and direct cost between minimal stimulation and conventional protocols on ovarian stimulation in in vitro fertilization

AIM

To determine whether minimal stimulation with clomiphene and gonadotropin provides outcomes and direct costs comparable with those of a conventional GnRHa-gonadotropin stimulation protocol for infertile patients undergoing in vitro fertilization.

METHODS

A non-randomized clinical trial was conducted from 1 July 1996 to 31 March 2003 at the Infertility and Assisted Reproductive Unit, Ramathibodi Hospital, Faculty of Medicine, Mahidol University, Thailand. A total of 192 patients were recruited of whom 96 cases underwent ovarian stimulated cycles with minimal stimulation protocol, and 96 controls underwent ovarian stimulated cycles with GnRHa-gonadotropin protocol, with cases and controls matched for age and infertility cause.

RESULTS

The median patient age was 35 years. Endometriosis was the most frequent infertility cause (28.1%). The conventional GnRHa-gonadotropin protocol could give more oocyte numbers than the minimal stimulation protocol (7.3 +/- 4.9 vs 4.5 +/- 3.3 oocytes). The fertilization rate and cleavage rate were similar (73.4 +/- 31.9 and 84.9 +/- 32.6 in minimal stimulation protocol, 69.3 +/- 29.6 and 88.4 +/- 28.0 in GnRHa-gonadotropin protocol, respectively). The pregnancy rate per oocyte retrieval cycle in the GnRHa-gonadotropin protocol was similar to the minimal stimulation protocol. (13.1%vs 13.0%, P = 1.000). However, the cost per pregnancy of minimal stimulation protocol was less than that of GnRHa-gonadotropin protocol. (6021.95 US dollars for minimal stimulation protocol per pregnancy, 10,785.65 US dollars for GnRHa-gonadotropin protocol per pregnancy, P < 0.000).

CONCLUSION

Minimal stimulation was less effective than conventional GnRHa-gonadotropin on the ovarian stimulation. However, the total costs of minimal stimulation were cheaper than the conventional GnRHa-gonadotropin protocol. The decreased costs of minimal stimulation justifies further evaluation of its role in the treatment of infertility in selected cases.

Gonadotropin-releasing hormone and reproductive medicine

The hypothalamic gonadotropin-releasing hormone (GnRH) is a key regulator of the reproductive system, mainly through its effects on pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release. Gonadotropin-releasing hormone analogues are modifications of the natural decapeptide, being either agonists (GnRHa) or antagonists. GnRHa may imitate the native hormone and induce an endogenous LH surge; however, sustained treatment with GnRHa results in complete refractoriness of LH and FSH production. This aspect of GnRHa action is the main application of the GnRHa in reproduction today. The hypogonadotropic hypogonadal state that results from the sustained treatment is the basis for additional applications of the GnRHa. The agonists appear to be effective, to some extent, for the treatment of endometriosis and were proved to be beneficial prior to surgery for fibroma uteri. GnRHa is used in assisted reproduction for both induction of an endogenous LH surge and for induction of ovulation, and its capacity to cause refractoriness of the pituitary may be used to avoid a premature LH surge. It is suggested that the GnRHa have a direct effect on ovarian steroidogenesis, which is independent of its action on the pituitary. This unwanted effect and other possible drawbacks of the agonists are thought to be eliminated with the use of the antagonists. The mechanism of action of these antagonists is through competitive blocking of the GnRH receptor, which results in a rapid but reversible suppression of gonadotropin secretion. As for GnRHa, GnRH antagonists have been proven effective to prevent the LH surge and to reduce the incidence of severe ovarian hyperstimulation syndrome in controlled ovarian stimulation cycles.

Neuroprotective peptide drug delivery and development: potential new therapeutics

Alzheimer's disease and related neurodegenerative disorders are prevalent among the elderly and might be considered as the plague of the 21st century. It is thus imperative to find cures for these conditions. The use of nerve growth factor proteins as neuroprotective therapeutics is limited by their hindered mobility through the blood-brain barrier. Peptides provide an attractive alternative. However, do peptide derivatives retain the activity of the entire protein? Are they stable? Would peptides cross the blood-brain barrier and what are the potential side effects? Examples are put forth to strengthen our opinion that peptides are important candidates for future drug development.