Antonios Koutselinis

Metallothionein: A multifunctional protein from toxicity to cancer

The metallothionein (MT) family is a class of low molecular weight, intracellular and cysteine-rich proteins presenting high affinity for metal ions. Although the members of this family were discovered nearly 40 years ago, their functional significance remains obscure. Four major MT isoforms, MT-1, MT-2, MT-3 and MT-4, have been identified in mammals. MTs are involved in many pathophysiological processes such as metal ion homeostasis and detoxification, protection against oxidative damage, cell proliferation and apoptosis, chemoresistance and radiotherapy resistance. MT isoforms have been shown to be involved in several aspects of the carcinogenic process, cancer development and progression. MT expression has been implicated as a transient response to any form of stress or injury providing cytoprotective action. Although MT participates in the carcinogenic process, its use as a potential marker of tumor differentiation or cell proliferation, or as a predictor of poor prognosis remains unclear. In the present review the involvement of MT in defense mechanisms to toxicity and in carcinogenicity is discussed.

Expression of peroxisome proliferator activated receptor-gamma in non-small cell lung carcinoma: correlation with histological type and grade

Peroxisome Proliferator Activated Receptor-gamma (PPAR-gamma) is a ligand-activated transcription factor belonging to the steroid receptor superfamily. It is a key regulator of adipogenic differentiation and glucose homeostasis, the ligands of which have also been demonstrated to induce differentiation in human breast, lung and colon cancer cell lines. In the present study, PPAR-gamma expression in cases of non-small cell lung carcinoma (NSCLC) was examined immunohistochemically and was correlated with tumor histological type and grade. Primary tumor samples from 147 patients with NSCLC were immunostained using a monoclonal antibody against PPAR-gamma. Positive PPAR-gamma immunostaining was prominent in 61 out of 147 cases (42%) and negative in the rest. PPAR-gamma positivity was prominent in 37 out of 79 cases (47%) of squamous cell lung carcinoma and in 24 out of 68 ones (35%) of lung adenocarcinoma. PPAR-gamma positivity was most frequently observed in squamous cell tumors (P=0.021) and in tumors of high histological grade of both histological types (P=0.041). Well-differentiated adenocarcinoma cases presented increased frequency for PPAR-gamma positivity compared with moderately and poorly differentiated ones (P=0.001). The intensity and pattern of PPAR-gamma staining in tumor cells were not correlated with histopathological parameters in PPAR-gamma positive cases of NSCLC examined. Our findings support evidence for participation of this protein in the biological mechanisms underlying the carcinogenic evolution in the lung, suggesting also the importance of specific PPAR-gamma ligands as future therapeutic approach in lung cancer.

Induction of metallothionein in the liver of carbon tetrachloride intoxicated rats: an immunohistochemical study.

Metallothioneins (MTs), are low molecular weight proteins, mainly implicated in metal ion detoxification. In the present study, we investigated the expression of hepatic MT in a rat model of injury and regeneration, induced by carbon tetrachloride (CCl(4)) administration. A single intraperitoneal injection of 1 ml CCl(4)/kg body weight was performed in male Wistar rats, killed at different time points post-administration. The enzymatic activities of aspartate and alanine aminotransferases in serum were determined, in addition to the liver histological findings, to estimate hepatotoxicity. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of thymidine kinase in liver tissue and the assessment of the mitotic index in hepatocytes, were used as indices of regeneration. MT was detected immunohistochemically in liver tissue sections. CCl(4) administration caused severe hepatic injury, followed by regeneration. MT expression became prominent as early as 12 h after the administration of CCl(4), in the nuclei of hepatocytes, while at 24 and 36 h intense cytoplasmic staining for MT appeared in the hepatocytes in the vicinity of necrotic areas. The peak of hepatocyte proliferative capacity, occurring at 48 h post-CCl(4) administration coincides with the maximum nuclear and cytoplasmic MT expression. At further time points MT expression presented a decreasing trend. Induction of MT expression was observed in the liver after a single administration of CCl(4), being more prominent at the time of maximum hepatocellular proliferation, participating actively in the replication of hepatocytes.

Clinical diagnoses and autopsy findings: a retrospective analysis of 252 cases in Greece.

CONTEXT Despite medical and technologic advances, clinicians may misdiagnose a patients situation and the cause of death. Autopsy may be valuable in uncovering the most frequent diagnostic pitfalls and helping clinicians to learn and to develop the medical art and science. OBJECTIVE To compare the clinical diagnoses with postmortem findings and evaluate the frequency of diagnostic errors assessed by autopsies. DESIGN Retrospective analysis of the protocols of 252 consecutive cases of adult patients autopsied in the Department of Forensic Medicine and Toxicology of Athens Medical School during the period 1999-2003. The outcome measures included concordance between diagnosis before death and at autopsy, sex, age, and length of hospitalization of the patient. RESULTS In 73 cases (29%), the autopsy findings confirmed the clinical diagnosis and the cause of death suggested by the clinicians. In 45 cases (19%), the clinical diagnosis and the cause of death suggested by the clinicians were discordant with the autopsy findings. In 105 cases (42%), the autopsy requests did not include any suggestion about the cause of the patients death. In 7 cases (3%), several diagnoses were suggested by the clinicians, and in 16 cases (6%), the comparison between clinical and postmortem diagnosis was not possible. The most frequently misdiagnosed diseases were coronary disease and pulmonary embolism. CONCLUSIONS It is concluded from this study that autopsies may reveal unexpected findings that are of critical importance and that a continued emphasis on autopsy evaluation is necessary to improve the quality of patient care.

Focal adhesion kinase expression is not a prognostic predictor in colon adenocarcinoma patients.

AIM Focal adhesion kinase (FAK) is an enzyme of the tyrosine kinase group linked to signaling pathways between cells and their extracellular matrix. FAK expression in tumor cells in vitro may correlate with their ability for invasion and metastasis. METHODS FAK protein expression was examined immunohistochemically in 80 cases of colon adenocarcinoma, and correlated with clinicopathological parameters; tumor proliferative capacity, reflected by Ki-67 antigen expression; and survival. RESULTS All tumor samples were FAK positive compared to normal colonic mucosa. FAK protein overexpression was seen in 32 out of 80 cases. FAK protein overexpression did not correlated with tumor histological grade, stage, Ki-67 positivity or survival. CONCLUSIONS Raised FAK protein expression was noted by immunohistochemistry in human colon carcinoma cases. The implication are discussed.

Expression of metallothionein in lung carcinoma: correlation with histological type and grade

Expression of metallothionein in lung carcinoma: correlation with histological type and grade

Metallothionein and heat shock protein expression during acute liver injury and regeneration in rats.

Abstract Metallothioneins (MT) are cytosolic proteins rich in cysteine which play a physiological role in metal ion homeostasis. Heat shock proteins (HSPs) are expressed in various organs in response to different stress stimuli. The purpose of the present study was to examine the intrahepatic distribution of MT and HSP-27, -70 and -90 in two different experimental models of acute liver injury and regeneration, induced by either thioacetamide, or carbon tetrachloride administration in male Wistar rats. Toxicological endpoints and markers of hepatocellular regeneration were assessed at various time points following toxin administration. The enzymatic activities of aspartate and alanine aminotransferases in serum, and histological findings in the liver were used to estimate toxin-induced injury. Tritiated thymidine incorporation into hepatic DNA, liver thymidine kinase activity and hepatocyte mitotic index were used to estimate liver regeneration. MT and HSPs were detected immunohistochemically. At the time of maximum liver injury, moderate MT and intense HSPs expression was prominent in hepatocytes in the vicinity of necrotic areas. At the time of maximum hepatocellular proliferation, intense MT and HSP-90 staining was evident in all hepatocytes, while at the same time, mild HSP-27 and HSP-70 immunoreactivity was noted. Our findings indicate that the differential distribution of MT and HSPs in the liver after toxin-induced injury, in common with the observed pattern of staining, reflect liver proliferating capacity.

The use of alcohol and other psychoactive substances by victims of traffic accidents in Greece

Alcohol is one of the main causes of traffic accidents worldwide. Its use decreases significantly the driving ability of an individual as well as the reflexes of a pedestrian increasing in this way the possibilities of their involvement in motor-vehicle accidents. The above possibilities are increased when a psychoactive substance has been taken in combination with alcohol due to their synergistic effect. The Laboratory of Forensic Medicine and Toxicology of the University of Athens is authorized to perform the toxicological investigation of traffic accidents that happen in the major part of Greece. The findings of the toxicological analyses that were performed in our laboratory during the years 1995 to 1997 are classified according to the alcohol concentration and the kind of psychoactive substance detected as well as to the gender and the age of the victims, drivers or pedestrians. The results of the above classification are evaluated and the conclusions regarding alcohol, drugs and traffic accidents in Greece are discussed thoroughly.

Metallothionein expression during liver regeneration after partial hepatectomy in cadmium-pretreated rats

Metallothionein is a low molecular mass protein inducible mainly by heavy metals, having high affinity for binding cadmium, zinc and copper. In the present study we investigated the expression of metallothionein in regenerating liver, at different time intervals, in cadmium pretreated partially hepatectomized rats. Liver metallothionein is highly expressed during regeneration in-duced by partial hepatectomy in rats, providing zinc within the rapidly growing tissue. Cadmium pretreatment caused inhibition of the first peak of liver regeneration, while metallothionein expression was markedly more prominent in the liver residues of cadmium-pretreated rats. These results demonstrate that although metallothionein able to bind temporarily metal ions as zinc and cadmium has been highly expressed, the liver regenerative process was inhibited possibly due to the effects of cadmium on other pivotal events necessary to the DNA replication.

The inferiorly based gastrocnemius muscle flap: anatomic aspects.

&NA; The arterial communication between the gastrocnemius muscle heads through their lowest anastomotic arteriole bundle alone was examined in specimens from 14 fresh cadavers. In 3 specimens, the larger vessels in close vicinity to the lowest vessels were preserved as well. Distinct communication between the arterial networks of the heads was demonstrated in all cases after injecting dyes through both sural arteries or into the lateral sural artery and the lowest anastomotic arteriole in 11 and 3 specimens, respectively. Therefore, it seems that one head can be adequately supplied from the contralateral one through their lowest anastomotic arteriole(s); nevertheless, the location of this vessel varies significantly and cannot be detected preoperatively. Measurements demonstrated that although this vessel is not found at a constant level, it is invariably detected in the lower third of the medial gastrocnemius heads length and, in 93 percent of cases, in the lower fourth. Thus, rough preoperative planning becomes feasible. Given that the venous communication between the heads has been documented as well, the authors think that an inferiorly based flap of the medial gastrocnemius head for defects of the middle third of the tibia might be both reliable and applicable; however, for reasons of safety, the muscle heads should remain attached along their lower third. (Plast. Reconstr. Surg. 106: 1312, 2000.)