Dimitrios Nikolopoulos

Local and systemic toxicity of nanoscale debris particles in total hip arthroplasty

Over the past 30 years joint replacement prostheses have been developed and refined to enhance durability and reproducibility. Total hip joint arthroplasty is being performed in an increasing number of younger patients; therefore orthopaedic surgeons seek implants with a longer life span. With regards to the progress of mechanical behaviour of the biomaterials used in an arthroplasty, little is known about the long‐term biological effects of wear debris. Owing to the composition of the prostheses currently in use, systemic exposure to chromium (Cr), cobalt (Co), nickel (Ni) and aluminium (Al) alloys occurs as a result of the formation of metal wear nano‐particles that are released both from metal‐on‐metal and polyethylene‐on‐metal bearings, resulting in a postoperative increase in metal ion levels at different organ sites. These particles circulate both locally and systemically, penetrate cell plasma membranes, bind to cellular proteins and enzymes and modulate cytokine expression. Their physiologic effects are poorly understood and their potential toxicity, hypersensitivity and carcinogenicity remain a cause for concern. In this article we will address the issue of whether these nanoscale degradation products are associated with adverse, clinically significant local or systemic toxicologic sequelae. Copyright

Ghrelin: A potential therapeutic target for cancer

Ghrelin is a recently identified 28-amino-acid peptide, capable of stimulating pituitary growth hormone release in humans and other mammals. It is mainly secreted from the gastric mucosa, but it is also widely expressed in a variety of tissues, in both normal and malignant conditions. Ghrelin has a multiplicity of physiological functions in gastrointestinal, cardiovascular, pulmonary and immune system, and also exerts a variety of roles, from increasing food intake (orexigenic effect) to affecting cell proliferation. The actions of ghrelin are mediated by the ghrelin receptor, also known as the growth hormone secretagogue receptor (GHS-R). The purpose of this review is to provide an overview of the expression and putative role of ghrelin and its receptor in cancer. Ghrelin and its receptor are detected in tumor tissues, and evidence is emerging that ghrelin plays an autocrine/paracrine role in cancer and could serve as a diagnostic or prognostic tool or as therapeutic target.

Ghrelin's role on gastrointestinal tract cancer

Ghrelin is a recently identified 28-amino-acid peptide, with pituitary growth hormone releasing activities in humans and other mammals. In mammals, ghrelin plays a variety of roles, including influence on food intake, gastric motility, and acid secretion of the gastrointestinal tract. It is mainly secreted from the stomach mucosa, but it is also expressed widely in other tissues - in normal and malignant conditions - and, therefore, ghrelin may exert such variable endocrine and paracrine effects, as autocrine and/or paracrine function in cancer. Ghrelins actions are mediated via its receptor, known as growth hormone secretagogue receptor (GHS-R), type 1a and 1b. Several endocrine and non-endocrine cancers, such as gastro-entero-pancreatic carcinoids, colorectal neoplasms, pituitary adenomas, pulmonary and thyroid tumours, as well as lung, breast, and pancreatic carcinomas express ghrelin at both mRNA and protein levels. In the current review, we summarise the available so far data with regard to: (a) the structure of the ghrelin molecule and its receptor; (b) its tissue contribution in physiologic and neoplasmatic conditions; and (c) ghrelins possible role in carcinogenesis; specifically, in the area of gastrointestinal tract cancer. The aim of the present study is to determine whether or not ghrelin promotes the proliferation rate of the gastrointestinal tract (GIT) tumours.

Radon survey in Greece—risk assesment

A large scale radon survey using track etch detectors has been carried out from 1995 to 1998 in Greece in order to estimate the radon concentrations in Greek dwellings and the exposure of the Greek population to radon. The total data set consisted of 1,277 samples. Residential potential alpha energy concentration values ranged between (0.024 +/- 0.009) and (8 +/- 1) WLM per year (P < 0.05) and effective doses between (0.09 +/- 0.04) and (28 +/- 4) mSv (P < 0.05). The mean lifetime risk for the Greek population due to radon was found to be 0.4%.

Doping and musculoskeletal system: short‐term and long‐lasting effects of doping agents

Doping is a problem that has plagued the world of competition and sports for ages. Even before the dawn of Olympic history in ancient Greece, competitors have looked for artificial means to improve athletic performance. Since ancient times, athletes have attempted to gain an unfair competitive advantage through the use of doping substances. A Prohibited List of doping substances and methods banned in sports is published yearly by the World Anti‐Doping Agency. Among the substances included are steroidal and peptide hormones and their modulators, stimulants, glucocorticosteroids, β2‐agonists, diuretics and masking agents, narcotics, and cannabinoids. Blood doping, tampering, infusions, and gene doping are examples of prohibited methods indicated on the List. Apart from the unethical aspect of doping, as it abrogates fair‐play’s principle, it is extremely important to consider the hazards it presents to the health and well‐being of athletes. The referred negative effects for the athlete’s health have to do, on the one hand, by the high doses of the performance‐enhancing agents and on the other hand, by the relentless, superhuman strict training that the elite or amateur athletes put their muscles, bones, and joints. The purpose of this article is to highlight the early and the long‐lasting consequences of the doping abuse on bone and muscle metabolism.

Obturator internus pyomyositis in a young adult: a case report and review of the literature

IntroductionThere has been a recent increase in the incidence of myositis worldwide. To this date, myositis has been described almost exclusively in children and adolescents. In most cases the causative agents are Gram-positive bacteria. When it involves muscles around the hip, other differential diagnoses such as septic arthritis and transient synovitis need to be excluded amongst others.Case presentationWe present the case of a 16 year old Caucasian male who suffered from pyomyositis of his left obturator internus muscle. He was pyrexial at 41°C with rigors and severe hip pain, whilst range of motion of his left hip was severely limited. Tenderness over the left pubic bone was significant. After clinical examination and relevant laboratory investigations, it was decided to treat him conservatively with intravenous antibiotics. Blood cultures grew Staphylococcus aureus resistant to amoxicillin and ampicillin. The patient was discharged fifteen days later. At the time of discharge, he was symptom-free.ConclusionThis form of pyomyositis is a rare pyogenic infection, which may be difficult to diagnose and can easily be missed. Therefore, physicians should familiarise themselves with this condition and consider it as a possible differential diagnosis in patients presenting with an acutely painful hip.

Comprehensive Review on the Biodiesel Production using Solid Acid Heterogeneous Catalysts

Biodiesel can be produced by domestic resources like straight vegetable oil, animal oil/fats, tallow and waste cooking oil. Its use, instead of the conventional diesel, contributes to the reduction of the CO2 emissions. Production of biodiesel occurring from base catalyzed transesterification of the oil, direct acid catalyzed transesterification of the oil and/or conversion of the oil to its fatty acids and then to biodiesel. Two types of catalytic mechanisms can be used for the biodiesel production. These are the homogenous and heterogeneous catalytic processes. However, heterogeneous catalysis can be identified as solid and enzymatic. In addition solid heterogeneous catalysts can be classified as acid or base. Ηeterogeneous solid acid catalysts are of a great importance for biodiesel production. The most known catalysts of this type are zeolites, mixed oxides, sulfonic acid group catalysts, sulfonic acid modified mesoporus silica, heteropoly acids and polyoxonetalates, supported and substituted heteropoly acids and solid acids catalysts based in waste carbon. The major advantages of this type of catalysts are their reusability, their non-toxic and non-corrosive attributes as well as decrement of the biodiesel production cost.

Self-organised critical features in soil radon and MHz electromagnetic disturbances: Results from environmental monitoring in Greece

This paper addresses the issues of self-organised critical behaviour of soil-radon and MHz-electromagnetic disorders during intense seismic activity in SW Greece. A significant radon signal is re-analysed for environmental influences with Fast Fourier Transform and multivariate statistics. Self-organisation of signals is investigated via fractal evolving techniques and detrended fluctuation analysis. New lengthy radon data are presented and analysed accordingly. The data did not show self-similarities. Similar analysis applied to new important concurrent MHz-electromagnetic signals revealed analogous behaviour to radon. The signals precursory value is discussed.

Current surgical strategies for total arthroplasty in valgus knee.

The majority of orthopaedic surgeons even currently agree that primary total arthroplasty in valgus knees with a deformity of more than ten degrees may prove challenging. The unique sets of bone and soft tissue abnormalities that must be addressed at the time of the operation make accurate axis restoration, component orientation and joint stability attainment a difficult task. Understanding the specific pathologic anatomic changes associated with the valgus knee is a prerequisite so as to select the proper surgical method, to optimize component position and restore soft-tissue balance. The purpose of this article is to review the valgus knee anatomical variations, to assess the best pre-operative planning and to evaluate how to choose the grade of constraint of the implant. It will also be underlying the up-to-date main approaches and surgical techniques be proposed in the English literature both for bone cuts and soft tissue management of valgus knees.

Radon Sources and Associated Risk in Terms of Exposure and Dose

Radon concerns the international scientific community from the early twentieth century, initially as radium emanation and nearly the second half of the century as a significant hazard to human health. The initial brilliant period of its use as medicine was followed by a period of intense concern for its health effects. Miners in Europe and later in the U.S were the primary target groups surveyed. Nowadays, there is a concrete evidence that radon and its progeny can cause lung cancer (1). Human activities may create or modify pathways increasing indoor radon concentration compared to outdoor background. These pathways can be controlled by preventive and corrective actions (2). Indoor radon and its short-lived progeny either attached on aerosol particles or free, compose an air mixture that carries a significant energy amount [Potential Alpha-Energy Concentration (PAEC)]. Prior research at that topic focused on the exposure on PAEC and the dose delivered by the human body or tissues. Special mention was made to the case of water workers due to inadequate data. Furthermore, radon risk assessment and relevant legislation for the dose delivered by man from radon and its progeny has been also reviewed.