Addressing the Challenges of Tuberculosis: A Brief Historical Account

Tuberculosis (TB) is a highly contagious disease that still poses a threat to human health. Mycobacterium tuberculosis (MTB), the pathogen responsible for TB, uses diverse ways in order to survive in a variety of host lesions and to subsequently evade immune surveillance; as a result, fighting TB and its associated multidrug resistance has been an ongoing challenge. The aim of this review article is to summarize the historical sequence of drug development and use in the fight against TB, with a particular emphasis on the decades between World War II and the dawn of the twenty first century (2000)

Η συμμετοχή της δίαιτας ανεπαρκούς σε χολίνη στην πειραματικά επαγώμενη πρόκληση κίρρωσης σε επίμυες

Choline is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions, in both humans and rodents (Blusztajin, 1998; Zeisel and Blusztajin, 1994). Besides being a component of various important biological compounds (including the membrane phospholipids lecithin, sphingomyelin and plasmalogen, the neurotransmitter acetylcholine and the platelet activating factor), Choline is also involved in many physiological functions (such as the metabolism of methyl groups and the lipid transport) (Zeisel., 1981; Buchman et al., 1992; Canty and Zeisel., 1994; Zeisel., 2000; Zeisel., 2003; Liapi et al., 2007). Moreover, being a component of certain phospholipids, Choline plays a critical role in generating second messengers for cell membrane signal transduction (Canty and Zeisel., 1994). The state of Choline-deficiency can be observed in various pathological (e.g. alcoholism, malnutrition) or physiological states (e.g. pregnancy, lactation), and may lead to hepatocellular modifications and fatty-liver induction (da Costa et al, 1993; Lombardi et al, 1968). It is well-established that dietary Choline-deprivation can result to decreased tissue S-adenosyl-L-methionine (SAM) levels, global DNA hypomethylation, hepatic steatosis, cirrhosis, and, ultimately, hepatic tumorigenesis in rodents (even in the absence of known carcinogens) (Buchman et al, 1995; Davis and Uthus, 2004). The administration of Choline deficient diet (CDD) has been used for the experimental induction of CD in animals, it provokes uncomplicated steatosis to the progressive inflammation and fibrinogenesis (Vetelainen et al, 2007). Thioacetamide (TAA) is a carcinogen and a hepatotoxicant that is also used for the experimental induction of hepatic lesions in rats (mainly, through the administration of large doses in the drinking water). Our current study focuses on the idea of the induction of prolonged CD in rats receiving TAA (through drinking water), as a novel approach and a potential experimental model of mild progressive hepatotoxicity that could simulate commonly presented cases in clinical practice (in which states of malnutrition and/or alcoholism are complicated by the development of other liver-associated diseases, as mentioned above). In this respect, we aimed to investigate the time-dependent effects of a 30-, a 60- and a 90-day dietary CDD and/or TAA administration (through drinking water) on the adult rat liver histological state and the serum markers of hepatic functional integrity. In particular, we aimed to evaluate: (a) the liver steatosis, fibrosis and hepatic cell-cycle turnover/mitosis (through histological evaluation), (b) the immunohistochemical expression of alpha-smooth muscle actin (α-SMA) as an important marker for the detection of activated stellate cells in response to liver injury (leading to collagen deposition and liver fibrosis), (c) the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for the assessment of liver parenchymal injury and/or inflammation, as well as (d) the serum levels of gammaglutamyltransferase (γ-GT) and alkaline phosphatase (ALP) for the assessment of liver injury and/or cholestatic liver injury, (d) mRNA expression of Matrix Metalloproteinases (MMP2 and MMP-9, and their tissue inhibitors TIMP-1and TIMP-2. (e) Serum inflammatory cytokines (¬-IFN, TNFα, IL-6, IL-10 and IL-4). […]Η χολίνη είναι μια λιποτρόπος ουσία (τεταρτοταγής αμίνη) που ανήκει στο σύμπλεγμα των βιταμινών Β και έχει χαρακτηρισθεί απαραίτητο συστατικό διατροφής. Αποτελεί βασικό συστατικών πολλών σημαντικών βιολογικών παραγόντων (συμπεριλαμβανομένων των φωσφολιπιδίων της μεμβράνης λεκιθίνη και σφιγγομυελίνη- της ακετυλοχολίνης και του PAF) και ως απαραίτητο συστατικό εμπλέκεται σε πολλές φυσιολογικές λειτουργίες όπως στο μεταβολισμό των μεθυλομάδων και τη μεταφορά των λιπιδίων χολίνης. Ως συστατικό ορισμένων φωσφολιπιδίων έχει ιδιαίτερα κριτικό ρόλο στον καταρράκτη μεταβίβασης σήματος. Έλλειψη χολίνης παρατηρείται σε διάφορες παθολογικές (αλκοολισμός, υποθρεψία) και φυσιολογικές καταστάσεις (κύηση-θηλασμός) μπορεί να οδηγήσει σε ηπατοκυτταρικές βλάβες και τη δημιουργία λιπώδους ήπατος ρόλο στ αποκτά συνεχώς αυξανόμενο κλινικό ενδιαφέρον δεδομένου ότι τα παράγωγα της συμμετέχουν σε πολλές φυσιολογικές λειτουργίες του οργανισμού. Δεδομένου ότι η διατροφή αποτελεί την κυριότερη πηγή της χολίνης για τον οργανισμό η χρόνια λήψη δίαιτας ανεπαρκούς σε χολίνη επιφέρει ηπατική δυσλειτουργία η οποία οφείλεται στη ηπατοκυτταρική συγκέντρωση της τριακυλογλυκερόλης και οδηγεί σε λιπώδη εκφύλιση του ήπατος, ενεργοποίηση της πρωτεϊνικής κινάσης C, απόπτωση και στις περιπτώσεις που η έλλειψη χολίνης είναι μακροχρόνια, την έναρξη καρκινογένεσης. Η χολίνη είναι ο μοναδικός διαιτητικός παράγων η έλλειψη του οποίου σχετίζεται με την ανάπτυξη νεοπλασιών και ειδικά ηπατικών χωρίς την παρουσία οποιασδήποτε ουσίας με γνωστή καρκινογόνο δράση. Σε επίμυς η χορήγηση δίαιτας ανεπαρκούς σε χολίνη όχι μόνο προάγει την έναρξη της νεοπλασματικής διεργασίας και αυξάνει την συχνότητα των ηπατοκαρκινωμάτων αλλά ευαισθητοποιεί και την κυτταρική εξαλλαγή από τις άλλες γνωστές καρκινογόνες ουσίες. Η θειοακεταμίδη (ΤΑΑ) είναι ισχυρή ηπατοτοξική ουσία και η οξεία χορήγηση της συνδέεται με κεντρολοβιώδη νέκρωση του ήπατος. Η παρατεταμένη χορήγησή της μπορεί να προκαλέσει υπερπλασία των χοληφόρων οδών καθώς και κίρρωση του ήπατος ιστολογικά όμοια με την προκαλούμενη από ιογενή ηπατίτιδα. Ο μεταβολισμός της ΤΑΑ έχει συνδεθεί με την οξειδωτική καταστροφή στην ηπατική βλάβη. Η ΤΑΑ επηρεάζει την έκφραση ορισμένων γονίδιων καθώς και πρωτεϊνών συμπεριλαμβανομένων της αλβουμίνης της β-ακτίνης της RNΑ-πολυμεράσης και της Ρ450 μονοξυγενάσης. Κατά τον μεταβολισμό της ΤΑΑ με τη δράση της φλαβινικής μονοξυγενάσης (flavin-containing monooxygenase FMO) και του κυτοχρώματος Ρ450 παράγονται ανιόντα υπεροξειδίου τα οποία τελικά οδηγούν στην παραγωγή υπεροξειδίου του υδρογόνου. Σκοπός της διατριβής είναι η μελέτη των δομικών λειτουργικών χημικών μεταβολών και βλαβών στο ήπαρ που προκαλεί η λήψη ΔΕΧ στην πειραματικώς επαγόμενη με θειοακεταμίδη (ΤΑΑ) πρόκληση κίρρωσης στους επίμυες. […

Genetic basis and gene therapy trials for thyroid cancer

Gene therapy is regarded as one of the most promising novel therapeutic approaches for hopeless cases of thyroid cancer and those not responding to traditional treatment. In the last two decades, many studies have focused on the genetic factors behind the origin and the development of thyroid cancer, in order to investigate and shed more light on the molecular pathways implicated in different differentiated or undifferentiated types of thyroid tumors. We, herein, review the current data on the main genes that have been proven to (or thought to) be implicated in thyroid cancer etiology, and which are involved in several well-known signaling pathways (such as the mitogen-activated protein kinase and phosphatidylinositol-3-kinase/Akt pathways). Moreover, we review the results of the efforts made through multiple gene therapy trials, via several gene therapy approaches/strategies, on different thyroid carcinomas. Our review leads to the conclusion that future research efforts should seriously consider gene therapy for the treatment of thyroid cancer, and, thus, should: (a) shed more light on the molecular basis of thyroid cancer tumorigenesis, (b) focus on the development of novel gene therapy approaches that can achieve the required antitumoral efficacy with minimum normal tissue toxicity, as well as (c) perform more gene therapy clinical trials, in order to acquire more data on the efficacy of the examined approaches and to record the provoked adverse effects

Choline deprivation: an overview of the major hepatic metabolic response pathways

Choline (Ch) is an important nutrient that is involved in many physiological functions. Deprivation of Ch (CD) may lead to hepatocellular modifications and/or even hepatic tumorigenesis and it can be a frequent problem in clinical settings; it can accompany various common pathological (alcoholism and malnutrition) or physiological states (pregnancy and lactation). The aim of this review is to provide an up-to-date overview of the major metabolic pathways involved in the hepatic response toward the experimentally or clinically induced CD, and to shed more light on the implicated (and probably interrelated) mechanisms responsible for the observed hepatocellular modifications and/or carcinogenesis

Oral Candida in Patients with Fixed Orthodontic Appliance: In Vitro Combination Therapy

Background. Fixed orthodontic appliance (FOA) increases the cariogenic microorganisms of mouth including candida. The aim was to evaluate the pharmacodynamic effects of some antibacterial drugs in combination with most applicable antifungal agents on candida isolated from patients with FOA. Methods. Three antifungal agents (amphotericin B (AMB), ketoconazole (KET), and itraconazole (ITZ)) and three antibacterial drugs (ciprofloxacin (CIP), doxycycline (DOX), and metronidazole (MET)) with serial concentrations have been used and microdilution broth method has been done for single and combination therapy, then fungal growth was assessed spectrophotometrically, and the combinations were evaluated by bliss independent analysis. Results. According to bliss independent interaction, the synergistic interactions depended on ΔE values that showed the best for CIP was with AMB (ΔE=55.14) followed with KET (ΔE=41.23) and lastly ITR (ΔE=39.67) at CIP = 150 mg/L. DOX was optimal with KET (ΔE=42.11) followed with AMB (ΔE=40.77) and the lowest with ITR (ΔE=9.12) at DOX = 75 mg/L. MET is the best with AMB (ΔE=40.95) and then with ITR (ΔE=35.45) and finally KET (ΔE=15.15) at MET 200 mg/L. Moreover, usage of higher concentrations of antibacterial agents revealed inhibitory effects. Conclusion. This study uncovers the optimum antibiotic combination therapy against cariogenic candida with FOA by usage of low therapeutic concentrations

Gestational exposure to cadmium alters crucial offspring rat brain enzyme activities: the role of cadmium-free lactation

The present study aimed to shed more light on the effects of gestational (in utero) exposure to cadmium (Cd) on crucial brain enzyme activities of Wistar rat offspring, as well as to assess the potential protective/restorative role that a Cd-free lactation might have on these effects. In contrast to earlier findings of ours regarding the pattern of effects that adult-onset exposure to Cd has on brain AChE, Na(+),K(+)- and Mg(2+)-ATPase activities, as well as in contrast to similar experimental approaches implementing the sacrificing mode of anaesthesia, in utero exposure to Cd-chloride results in increased AChE and Na(+),K(+)-ATPase activities in the newborn rat brain homogenates that were ameliorated through a Cd-free lactation (as assessed in the brain of 21-day-old offspring). Mg(2+)-ATPase activity was not found to be significantly modified under the examined experimental conditions. These findings could provide the basis for a further evaluation of the herein discussed neurotoxic effects of in utero exposure to Cd, in a brain region-specific manner

Hepatic injury due to combined choline-deprivation and thioacetamide administration: an experimental approach to liver diseases

Background: The induction of prolonged choline-deprivation (CD) in rats receiving thioacetamide (TAA) is an experimental approach of mild hepatotoxicity that could resemble commonly presented cases in clinical practice (in which states of malnutrition and/or alcoholism are complicated by the development of other liver-associated diseases). Aim: The present study aimed to investigate the time-dependent effects of a 30-, a 60- and a 90-day dietary CD and/or TAA administration on the adult rat liver histopathology and the serum markers of hepatic functional integrity. Methods: Rats were divided into four main groups: (a) control, (b) CD, (c) TAA and (d) CD + TAA. Dietary CD was provoked through the administration of choline-deficient diet, while TAA administration was performed ad libitum through the drinking water (300 mg/l of drinking water). Results: Histological examination of the CD + TAA liver sections revealed micro- and macro-vesicular steatosis with degeneration and primary fibrosis at day 30, to extensive steatosis and fibrosis at day 90. Steatosis was mostly of the macrovesicular type, involving all zones of the lobule, while inflammatory infiltrate consisted of foci of acute and chronic inflammatory cells randomly distributed in the lobule. These changes were accompanied by gradually increasing mitotic activity, as well as by a constantly high alpha-smooth muscle actin immunohistochemical staining. The determination of hepatocellular injury markers such as the serum enzyme levels’ of alanine aminotransferase and aspartate aminotransferase demonstrated a decrease at day 30 (they returned to control levels at days 60 and 90). However, the determination of those serum enzymes used for the assessment of cholestatic liver injury (gamma-glutamyltransferase, alkaline phosphatase) revealed a constant (time-independent) statistically-significant increase versus control values. Conclusions: Long-term combined dietary CD and TAA administration could be a more realistic experimental approach to human liver diseases involving severe steatosis, fibrosis, stellate cell activation and significant regenerative hepatocellular response

Choline-deprivation alters crucial brain enzyme activities in a rat model of diabetic encephalopathy

Diabetic encephalopathy describes the moderate cognitive deficits, neurophysiological and structural central nervous system changes associated with untreated diabetes. It involves neurotoxic effects such as the generation of oxidative stress, the enhanced formation of advanced glycation end-products, as well as the disturbance of calcium homeostasis. Due to the direct connection of choline (Ch) with acetylcholine availability and signal transduction, a background of Ch-deficiency might be unfavorable for the pathology and subsequently for the treatment of several metabolic brain diseases, including that of diabetic encephalopathy. The aim of this study was to shed more light on the effects of adult-onset streptozotocin (STZ)-induced diabetes and/or Ch-deprivation on the activities of acetylcholinesterase (AChE) and two important adenosinetriphosphatases, namely Na+,K+-ATPase and Mg2+-ATPase. Male adult Wistar rats were divided into four main groups, as follows: control (C), diabetic (D), Ch-deprived (CD), and Ch-deprived diabetic (D+CD). Deprivation of Ch was provoked through the administration of Ch-deficient diet. Both the induction of diabetes and the beginning of dietary-mediated provoking of Ch-deprivation occurred at the same day, and rats were killed by decapitation after 30 days (1 month; groups C1, D1, CD1 and D1+CD1) and 60 days (2 months; groups C2, D2, CD2 and D2+CD2, respectively). The adult rat brain AChE activity was found to be significantly increased by both diabetes (+10%, p < 0.001 and +11%, p < 0.01) and Ch-deprivation (+19%, p < 0.001 and +14%, p < 0.001) when compared to the control group by the end of the first (C1) and the second month (C2), respectively. However, the Ch-deprived diabetic rats’ brain AChE activity was significantly altered only after a 60-day period of exposure, resulting in a +27% increase (D2+CD2 vs. C2, p < 0.001). Although the only significant change recorded in the brain Na+,K+-ATPase activity after the end of the first month is attributed to Ch-deprivation (+21%, p < 0.05, CD1 vs. C1), all groups of the second month exhibited a statistically significant decrease in brain Na+,K+-ATPase activity (−24%, p < 0.01, D2 vs. C2; −21%, p < 0.01, CD2 vs. C2; −22%, p < 0.01, D2+CD2 vs. C2). As concerns Mg2+-ATPase, the enzyme’s activity demonstrates no significant changes, with the sole exception of the D2+CD2 group (+21%, p < 0.05, D2+CD2 vs. C2). In addition, statistically significant time-dependent changes concerning the brain Mg2+-ATPase activity were recorded within the diabetic (p < 0.05, D2 vs. D1) and the Ch-deprived (p < 0.05, CD2 vs. CD1) rat groups. Our data indicate that Ch-deprivation seems to be an undesirable background for the above-mentioned enzymatic activities under untreated diabetes, in a time-evolving way. Further studies on the issue should focus on a region-specific reevaluation of these crucial enzymes’ activities as well as on the possible oxidative mechanisms involved

Effects of experimentally-induced maternal hypothyroidism on crucial offspring rat brain enzyme activities

Hypothyroidism is known to exert significant structural and functional changes to the developing central nervous system, and can lead to the establishment of serious mental retardation and neurological problems. The aim of the present study was to shed more light on the effects of gestational and/or lactational maternal exposure to propylthiouracil-induced experimental hypothyroidism on crucial brain enzyme activities of Wistar rat offspring, at two time-points of their lives: at birth (day-1) and at 21 days of age (end of lactation). Under all studied experimental conditions, offspring brain acetylcholinesterase (AChE) activity was found to be significantly decreased due to maternal hypothyroidism, in contrast to the two studied adenosinetriphosphatase (Na(+),K(+)-ATPase and Mg(2+)-ATPase) activities that were only found to be significantly altered right after birth (increased and decreased, respectively, following an exposure to gestational maternal hypothyroidism) and were restored to control levels by the end of lactation. As our findings regarding the pattern of effects that maternal hypothyroidism has on the above-mentioned crucial offspring brain enzyme activities are compared to those reported in the literature, several differences are revealed that could be attributed to both the mode of the experimental simulation approach followed as well as to the time-frames examined. These findings could provide the basis for a debate on the need of a more consistent experimental approach to hypothyroidism during neurodevelopment as well as for a further evaluation of the herein presented and discussed neurochemical (and, ultimately, neurodevelopmental) effects of experimentally-induced maternal hypothyroidism, in a brain region-specific manner

Experimentally-induced Wernicke's encephalopathy modifies crucial rat brain parameters: the importance of Na+,K+-ATPase and a potentially neuroprotective role for antioxidant supplementation

Wernicke's encephalopathy (WE) is a serious neuropsychiatric syndrome caused by chronic alcoholism and thiamine (T) deficiency. Our aim was to shed more light on the pathophysiology of WE, by introducing a modified in vivo experimental model of WE and by focusing on changes provoked in the total antioxidant status (TAS) and three crucial brain enzyme activities in adult rats. Rats were placed on ethanol (EtOH) consumption (20 % v/v) for a total of 5 weeks. By the end of the third week, rats were fed a T-deficient diet (TDD) and were treated with pyrithiamine (PT; 0.25 mg/kg) for the remaining 2 weeks. Following the induction of WE symptomatology, rats were treated with three consecutive (every 8 h) injections of saline or T (100 mg/kg) and were sacrificed. Brain homogenates were generated and used for spectrophotometrical evaluation of TAS and enzymatic activities. Additionally, in vitro experiments were conducted on brain homogenates or pure enzymes incubated with T or neuromodulatory antioxidants. Pre-exposure to EtOH provided a successful protocol modification that did not affect the expected time of WE symptomatology onset. Administration of T ameliorated this symptomatology. WE provoked oxidative stress that was partially limited by T administration, while T itself also caused oxidative stress to a smaller extent. Brain acetylcholinesterase (AChE) was found inhibited by WE and was further inhibited by T administration. In vitro experiments demonstrated a potential neuroprotective role for L-carnitine (Carn). Brain sodium-potassium adenosine triphosphatase (Na(+),K(+)-ATPase) activity was found increased in WE and was reduced to control levels by in vivo T administration; this increase was also evident in groups exposed to PT or to TDD, but not to EtOH. In vitro experiments demonstrated a potential neuroprotective role for this Na(+),K(+)-ATPase stimulation through T or L-cysteine (Cys) administration. Brain magnesium adenosine triphosphatase (Mg(2+)-ATPase) activity was found decreased by prolonged exposure to EtOH, but was not affected by the experimental induction of WE. Our data suggest that T administration inhibits AChE, which is also found inhibited in WE. Moreover, increased brain Na(+),K(+)-ATPase activity could be a marker of T deficiency in WE, while combined T and antioxidant co-supplementation of Cys and/or Carn could be neuroprotective in terms of restoring the examined crucial brain enzyme activities to control levels