Endometrial carcinoma in high‐risk populations: is it time to consider a screening policy?

Endometrial carcinoma (EC) is the leading female genital tract malignancy in industrialized countries. It will become an important public health problem in the coming years in the USA and Europe, where its incidence is increasing, and next‐generation interventions should include periodical screening in high‐risk women. In this review, we discuss the importance to gynaecologists of detecting women at high risk and offering an adequate screening programme. Screening for EC is particularly challenging and there is currently no proven programme for the surveillance of women estimated to be at an increased risk of developing this form of cancer. The data in the literature, including this and previous issues of Cytopathology, and personal experience suggest that endometrial liquid‐based cytology (LBC) might play an essential role in a screening policy for EC. LBC may enable practitioners to reduce age‐adjusted mortality for women at high risk for EC.     

Two vicinal cysteines confer a peculiar redox regulation to low molecular weight protein tyrosine phosphatase in response to platelet-derived growth factor receptor stimulation.

Low molecular weight protein tyrosine phosphatase (LMW-PTP) is an enzyme involved in platelet-derived growth factor (PDGF)-induced mitogenesis and cytoskeleton rearrangement because it is able to bind and dephosphorylate the activated receptor. LMW-PTP presents two cysteines in positions 12 and 17, both belonging to the catalytic pocket; this is a unique feature of LMW-PTP among all protein tyrosine phosphatases. Our previous results demonstrated that in vitro LMW-PTP is oxidized by either H(2)O(2) or nitric oxide with the formation of a disulfide bond between Cys-12 and Cys-17. This oxidation leads to reversible enzyme inactivation because treatment with reductants permits catalytic activity rescue. In the present study we investigated the in vivo inactivation of LMW-PTP by either extracellularly or intracellularly generated H(2)O(2), evaluating its action directly on its natural substrate, PDGF receptor. LMW-PTP is oxidized and inactivated by exogenous oxidative stress and recovers its activity after oxidant removal. LMW-PTP is oxidized also during PDGF signaling, very likely upon PDGF-induced H(2)O(2) production, and recovers its activity within 40 min. Our results strongly suggest that reversibility of in vivo LMW-PTP oxidation is glutathione-dependent. In addition, we propose an intriguing and peculiar role of Cys-17 in the formation of a S-S intramolecular bond, which protects the catalytic Cys-12 from further and irreversible oxidation. On the basis of our results we propose that the presence of an additional cysteine near the catalytic cysteine could confer to LMW-PTP the ability to rapidly recover its activity and finely regulate PDGF receptor activation during both extracellularly and intracellularly generated oxidative stress.     

Genetic analysis of mutagenesis in aging Escherichia coli colonies

Bacteria live in unstructured and structured environments, experiencing feast and famine lifestyles. Bacterial colonies can be viewed as model structured environments. SOS induction and mutagenesis have been observed in aging Escherichia coli colonies, in the absence of exogenous sources of DNA damage. This cAMP-dependent mutagenesis occurring in Resting Organisms in a Structured Environment (ROSE) is unaffected by a umuC mutation and therefore differs from both targeted UV mutagenesis and recA730 (SOS constitutive) untargeted mutagenesis. As a recB mutation has only a minor effect on ROSE mutagenesis it also differs from both adaptive reversion of the lacI33 allele and from iSDR (inducible Stable DNA Replication) mutagenesis. Besides its recA and lexA dependence, ROSE mutagenesis is also uvrB and polA dependent. These genetic requirements are reminiscent of the untargeted mutagenesis in λ phage observed when unirradiated λ infects UV-irradiated E. coli. These mutations, which are not observed in aging liquid cultures, accumulate linearly with the age of the colonies. ROSE mutagenesis might offer a good model for bacterial mutagenesis in structured environments such as biofilms and for mutagenesis of quiescent eukaryotic cells. Received: 30 April 1997 / Accepted: 1 July 1997     

Male gonads morphology,spermatogenesis and sperm ultrastructure of the seahorse Hippocampus guttulatus (Syngnathidae)

Testes morphology, spermatogenetic process and mature sperm ultrastructure were analysed in Hippocampus guttulatus, using both light and transmission electron microscopy. Both testes were organized in a single large germinal compartment, with a central lumen. Spermatocysts only contained spermatogonia and primary spermatocytes. Inside the testis lumen, together with mature sperm, two types of large mono‐nucleate cells, flagellate and aflagellate, were present. Both types of cells were interpreted as developing germ cells precociously released inside the testis lumen, where their maturation was completed. According to the different morphological features of the nuclei, such as chromatin condensation degree, aspect of the nuclear fossa and others, the flagellate cells were unquestionably developing spermatids. On the contrary, the developmental stage of the aflagellate was more difficult to interpreted. They could be secondary spermatocytes or young spermatids. No dimorphic sperm were recognizable, the only sperm type observed have features typical of the intro‐sperm reports in other syngnathids species. They had a cylindrical head, a short midpiece, characterized by two mitochondrial rings housed inside a cytoplasmic collar, and a long flagellum. These and previous data about the same topic reported on other syngnathids species were compared and discussed.     

A histological and immunohistochemical study of the effects of N-acetyl cysteine on retinopathy of prematurity by modifying insulin-like growth factor-1

Retinopathy of prematurity (ROP) is a vasoproliferative disorder that occurs in premature infants and may lead to permanent visual impairment. We investigated both the possible protective role of N-acetyl cysteine (NAC) for preventing ROP and the role of IGF-1 in the disorder. Forty-five newborn rats were divided into three groups. Group 1 was raised in room air as controls. Group 2 was exposed to 60% oxygen for 14 days after birth, then transferred to room air. Group 3 was exposed to the same conditions as group 2, but received intraperitoneal injections of NAC on postnatal days 7–17. After 35 days, both eyes of all rats were processed for histology. Some sections were stained with hematoxylin and eosin to assess structural changes and other sections were immunostained to determine the location of IGF-1. Frozen sections also were prepared and stained for adenosine triphosphatase to detect retinal blood vessels. Compared to the controls, more blood vessels, many of which were abnormal, and increased IGF-1 expression were observed in group 2. In group 3, abnormal blood vessels and IGF-1 expression were less evident. NAC appeared to be an effective vascular-protective agent for ROP by decreasing IGF-1 expression.     

3D Reconstruction of the Human Airway Mucosa In Vitro as an Experimental Model to Study NTHi Infections

We have established an in vitro 3D system which recapitulates the human tracheo-bronchial mucosa comprehensive of the pseudostratified epithelium and the underlying stromal tissue. In particular, we reported that the mature model, entirely constituted of primary cells of human origin, develops key markers proper of the native tissue such as the mucociliary differentiation of the epithelial sheet and the formation of the basement membrane. The infection of the pseudo-tissue with a strain of NonTypeable Haemophilus influenzae results in bacteria association and crossing of the mucus layer leading to an apparent targeting of the stromal space where they release large amounts of vesicles and form macro-structures. In summary, we propose our in vitro model as a reliable and potentially customizable system to study mid/long term host-pathogen processes.     

Conserved sequences in enzymes of the UDP-GlcNAc/MurNAc family are essential in hamster UDP-GlcNAc:dolichol-P GlcNAc-1-P transferase

The UDP-GlcNAc/MurNAc family of eukaryotic and prokaryotic enzymes use UDP-GlcNAc or UDP-MurNAc-pentapeptide as donors, dolichol-P or polyprenol-P as acceptors, and generate sugar-P-P-polyisoprenols. A series of six conserved sequences, designated A through F and ranging from 5 to 13 amino acid residues, has been identified in this family. To determine whether these conserved sequences are required for enzyme function, various mutations were examined in hamster UDP- GlcNAc:dolichol-P GlcNAc-1-P transferase (GPT). Scramble mutations of sequences B-F, generated by scrambling the residues within each sequence, demonstrated that each is important in GPT. While E and F scrambles appeared to prevent stable expression of GPT, scrambling of B- D resulted in GPT mutants that could be stably expressed and bound tunicamycin, but lacked enzymatic activity. Further, the C and D scramble mutants had an unexpected sorting defect. Replacement of sequences B-F with prokaryotic counterparts from either the B.subtilis mraY or E.coli rfe genes also affected GPT by preventing expression of the mutant protein (B, F) or inhibiting its enzymatic activity (C-E). For the C-E replacements, no acquisition of acceptor activity for polyprenol-P, the fully unsaturated natural bacterial acceptor, was detected. These studies show that the conserved sequences of the UDP- GlcNAc/MurNAc family are important, and that the eukaryotic and prokaryotic counterparts are not freely interchangeable. Since several mutants were efficiently expressed and bound tunicamycin, yet lacked enzymatic activity, the data are consistent with these sequences having a direct role in product formation.      

Genetic Architecture Promotes the Evolution and Maintenance of Cooperation

When cooperation has a direct cost and an indirect benefit, a selfish behavior is more likely to be selected for than an altruistic one. Kin and group selection do provide evolutionary explanations for the stability of cooperation in nature, but we still lack the full understanding of the genomic mechanisms that can prevent cheater invasion. In our study we used Aevol, an agent-based, in silico genomic platform to evolve populations of digital organisms that compete, reproduce, and cooperate by secreting a public good for tens of thousands of generations. We found that cooperating individuals may share a phenotype, defined as the amount of public good produced, but have very different abilities to resist cheater invasion. To understand the underlying genetic differences between cooperator types, we performed bio-inspired genomics analyses of our digital organisms by recording and comparing the locations of metabolic and secretion genes, as well as the relevant promoters and terminators. Association between metabolic and secretion genes (promoter sharing, overlap via frame shift or sense-antisense encoding) was characteristic for populations with robust cooperation and was more likely to evolve when secretion was costly. In mutational analysis experiments, we demonstrated the potential evolutionary consequences of the genetic association by performing a large number of mutations and measuring their phenotypic and fitness effects. The non-cooperating mutants arising from the individuals with genetic association were more likely to have metabolic deleterious mutations that eventually lead to selection eliminating such mutants from the population due to the accompanying fitness decrease. Effectively, cooperation evolved to be protected and robust to mutations through entangled genetic architecture. Our results confirm the importance of second-order selection on evolutionary outcomes, uncover an important genetic mechanism for the evolution and maintenance of cooperation, and suggest promising methods for preventing gene loss in synthetically engineered organisms.