Neuroectodermal ovarian tumors: a brief overview

Primary neuroectodermal tumors of the ovary are rare monophasic teratomas composed exclusively or almost exclusively of neuroectodemal tissue. Approximately 60 neuroectodermal tumors of the ovary have been reported in the literature. These tumors were classified as ependymoma, astrocytoma, glioblastoma multiforme, ependymoblastoma or as primitive neuroepithelial tumors such as medullo-blastoma, medulloepithelioma and neuroblastoma. Most tumors were diagnosed in the third and fourth decades of life, but occasionally they were first discovered in children, adolescents or older women. Microscopically, they are identical to equivalent neuroectodermal tumors of the central nervous system. The review of the literature shows that most patients with clinical stage I and II were treated surgically, whereas those with stage III or IV tumors received additional radiation or chemotherapy, or both. The clinical stage at the time of diagnosis is the most important prognostic parameter of these tumors.     

Cell fractionation of parasitic protozoa: a review

Cell fractionation, a methodological strategy for obtaining purified organelle preparations, has been applied successfully to parasitic protozoa by a number of investigators. Here we present and discuss the work of several groups that have obtained highly purified subcellular fractions from trypanosomatids, Apicomplexa and trichomonads, and whose work have added substantially to our knowledge of the cell biology of these parasites.     

Transport ATPases in biological systems and relationship to human disease: a brief overview

Interest in the field of transport ATPases has grown dramatically during the past 20 years and gained considerable visibility for several reasons. First, it was shown that most transport ATPases can be lumped into only a few categories designated simply as P, V, F, and ABC types, the latter consisting of a large superfamily. Second, it has been shown that many transport ATPases have a clear relevance to human disease. Third, the field of transport ATPases has become rather advanced in the study of the reaction mechanisms and structure–function relationships associated with several of these enzymes. Finally, the Nobel committee recently recognized major accomplishments in this field of research. Here, the author provides a brief discussion of transport ATPases that are present in biological systems and their relevance or possible relevance to human disease.     

Matrix metalloproteinases in plants: a brief overview

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases belonging to the metzincin clan. MMPs have been characterized in detail in mammals, and they have been shown to play key roles in many physiological and pathological processes. Plant MMP-like proteases exist, but relatively few have been characterized. It has been speculated that plant MMPs are involved in remodeling of the plant extracellular matrix during growth, development and stress response. However, the precise functions and physiological substrates in higher plants remain to be determined. In this brief overview, we summarize the current knowledge of MMPs in higher plants and algae.     

In vitro fertilization and embryo transfer: a brief overview

The in vitro fertilization process breaks down into three essential components: induction of ovulation, fertilization of the oocyte, and development of embryos that are transferred into the uterus. Problems may arise resulting in failure at any one of these junctions. In 1984, the World Congress on In Vitro Fertilization was held, looking at 9,641 laparoscopies yielding 1,101 clinical pregnancies, with an overall pregnancy rate of 11 percent--clearly indicating that in vitro fertilization/embryo transfer (IVF/ET) was an idea whose time had come. Ovulation induction is monitored by both the use of ultrasound and daily estradiol levels, ultrasound indicating the number of oocytes that will be available for capture, and estradiol indicating in an indirect way the quality of those oocytes. It is a major aim in each patient to obtain at least four embryos, since this optimizes success rates. Ovulation induction at Yale is carried out with a high-dose human menopausal gonadotropin (HMG)/human chorionic gonadotropin (HCG) regimen. This regimen has insured us a success rate of 17 percent clinical pregnancies per laparoscopy. In the future, modification will occur in the process with cryopreservation of oocytes and embryos, and gamete manipulation. The modifications will be effected primarily to increase pregnancy rates. Research will continue mainly to delineate better biochemical markers for oocyte quality, but also to further explain the mystery of implantation.     

Polymeric aspects of protein folding: a brief overview

Regardless of the differences in primary amino acid sequences, protein molecules in a number of conformational states behave as polymer homologues, allowing speculations as to the volume interactions being a driving force in formation of equilibrium structures. For instance, both native and molten globules exhibit key features of polymer globules, where the fluctuations of the molecular density are expected to be much less than the molecular density itself. Protein molecules in the compact denatured (pre-molten globule) states possess properties of squeezed coils. In fact, even high concentrations of strong denaturants (e.g., urea and GdmCl) more likely constitute bad solvents for protein chains. Thus, globular proteins are probably never random coils without positional correlations and biological polypeptide chains represent the macromolecular coils below a critical point even under harsh denaturing conditions. Several implications of these findings to protein folding are discussed.     

Side effects of atypical antipsychotics: a brief overview

This paper reviews the available evidence concerning the side effects of atypical antipsychotics, including weight gain, type II diabetes mellitus, hyperlipidemia, QTc interval prolongation, myocarditis, sexual side effects, extrapyramidal side effects and cataract. Some recommendations about how to prevent and manage these side effects are also provided. It is concluded that atypical antipsychotics do not represent a homogeneous class, and that differences in side effects should be taken into account by clinicians when choosing an antipsychotic for an individual patient.     

Iron and bacterial virulence — a brief overview

Summary Iron is now recognized as playing a vital role in infection. Not only does its restricted availability in tissue fluids present microbial pathogens with the problem of acquiring sufficient for multiplication in vivo, but it also constitutes a major environmental signal which co-ordinately regulates the expression of a number of virulence and metabolic genes. Progress in understanding the strategies used by pathogens for acquiring iron in vivo, and their responses to iron restriction, is providing a fresh insight into microbial pathogenicity.     

Cell death pathology: perspective for human diseases

Apoptosis, a genetically regulated form of cell death with distinct biochemical and morphological features, plays a relevant physiological and pathological role in the organism, being pivotal in the maintenance of tissue development and homeostasis in the adult as well as in the regulation of immune responses. Deregulation of this process causes several human disorders including cancer, autoimmune and neurodegenerative diseases. Thus, modulation of the apoptotic process and of cell death in general, is a potential therapeutic approach for the treatment of several human pathologies.     

Cell death induced by vincristine in the intestinal crypts of mice and in a human Burkitt's lymphoma cell line

Abstract. Although vincristine is widely used clinically in the treatment of some human cancers, its mechanism of action has not been clearly established. In this study, the patterns of cell death induced y vincristine in the intestinal crypts of mice and in a human Burkitt's lymphoma cell line were investigated by light and electron microscopy. Vincristine was found to enhance apoptosis of interphase cells in both systems and also to cause the arrest of cells in mitosis, the latter effect being ore pronounced in the intestinal crypts. Arrested mitotic cells went on to die by a process that had a number of features in common with apoptosis. These include compaction of chromatin (following coalescence of chromosomes), condensation of the cytoplasm, initial preservation of organelle integrity, and eventually the fragmentation of the cell into a number of membrane-enclosed bodies which are morphologically similar to conventional apoptotic bodies. The results suggest that the cytocidal effect of vincristine is not solely dependent on metaphase arrest but is a cumulative one, resulting both from apoptosis of interphase cells and the 'apoptotic-like' death of cells arrested in metaphase.     

Photosystem 2 and the oxygen evolving complex: a brief overview

These special issues of photosynthesis research present papers documenting progress in revealing the many aspects of photosystem 2, a unique, one-of-a-kind complex system that can reduce a plastoquinone to a plastoquinol on every second flash of light and oxidize 2 H₂O to an O₂ on every fourth flash. This overview is a brief personal assessment of the progress observed by the author over a four-decade research career, including a discussion of some remaining unsolved issues. It will come as no surprise to readers that there are remaining questions given the complexity of PS2, and the efforts that have been needed so far to uncover its secrets. In fact, most readers will have their own lists of outstanding questions.

     

Prenatal effects of alcohol on growth: a brief overview

Intrauterine growth retardation is the most reliable consequence of prenatal exposure to alcohol in both humans and animals. The decrease in fetal growth is caused by alcohol, not by congeners present in alcoholic beverages. The most likely hypothesis whereby alcohol decreases growth is via hypoxia, which interferes with cellular processes that require oxygen to function adequately, e.g., placental transport and protein synthesis. The third trimester of pregnancy is when alcohol exerts its greatest impact on fetal growth.     

DNA topoisomerases in life and death: implications in kinetoplastid protozoa

Current biomedical research has its focus on the search for newer intervention strategies to control public health impact of parasitic diseases. The dramatic advances of molecular and cellular biology in recent times have provided opportunities for discovering and evaluating molecular targets for drug designing, which now form a rational basis for the development of improved anti parasitic therapy. DNA topoisomerases, the "cellular magicians" involved in nearly all biological processes governing DNA, have emerged as one such biological target. Over the last two decades, interest in topoisomerases has expanded beyond the realm of the basic science laboratory into the clinical arena. This review aims at providing a comprehensive insight into the biology of DNA topoisomerases and also focus on its evolution as a drug target in the unicellular kinetoplastids.