An application of the density standard and scaled-pixel-counting protocol to assess the radiodensity of equine incisor teeth affected by resorption and hypercementosis: preliminary advancement in dental radiography.

BACKGROUND: Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) syndrome is a dental disease where the radiographic signs may be quantified using radiographic texture features. This study aimed to implement the scaled-pixel-counting protocol to quantify and compare the image structure of teeth and the density standard in order to improve the identification of the radiographic signs of tooth resorption and hypercementosis using the EOTRH syndrome model. METHODS AND RESULTS: A detailed examination of the oral cavity was performed in 80 horses and maxillary incisor teeth were evaluated radiographically, including an assessment of the density standard. On each of the radiographs, pixel brightness (PB) was extracted for each of the ten steps of the density standard (S1-S10). Then, each evaluated incisor tooth was assigned to one of 0-3 EOTRH grade-related groups and annotated using region of interest (ROI). For each ROI, the number of pixels (NP) from each range was calculated. The linear relation between an original X-ray beam attenuation and PB was confirmed for the density standard. The NP values increased with the number of steps of the density standard as well as with EOTRH degrees. Similar accuracy of the EOTRH grade differentiation was noted for data pairs EOTRH 0-3 and EOTRH 0-1, allowing for the differentiation of both late and early radiographic signs of EOTRH. CONCLUSION: The scaled-pixel-counting protocol based on the use of density standard has been successfully implemented for the differentiation of radiographic signs of EOTRH degrees.

Optical Spectra of Oligofurans: A Theoretical Approach to the Transition Energies, Reorganization Energies, and the Vibronic Activity.

There is experimental evidence of high vibronic activity that accompanies the allowed transition between the ground state and the lowest electronic singlet excited state of oligofurans that contain two, three, and four furan rings. The absorption and emission spectra of the three lowest oligofurans measured at liquid nitrogen temperature show distinct fine structures that are reproduced using the projection-based model of vibronic coupling (with Dushinsky rotation included) parameterized utilizing either Density Functional Theory (DFT, with several different exchange-correlation functionals) or ab initio (CC2) quantum chemistry calculations. Using as a reference the experimental data concerning the electronic absorption and fluorescence for the eight lowest oligofurans, we first analyzed the performance of the exchange-correlation functionals for the electronic transition energies and the reorganization energies. Subsequently, we used the best functionals alongside with the CC2 method to explore how the reorganization energies are distributed among the totally symmetric vibrations, identify the normal modes that dominate in the fine structures present in the absorption and emission bands, and trace their evolution with the increasing number of rings in the oligofuran series. Confrontation of the simulated spectra with the experiment allows for the verification of the performance of the selected DFT functionals and the CC2 method.

[Dehumanizacja wspólczesnej medycyny: przyczyny i przeciwdzialanie].

A discussion of causes of dehumanisation in contemporary medicine and possible methods of preventing this situation. The causes can be divided into external, associated with the influence of the environment of civilisation, and internal, which constitute a form of aunwanted side effects" of the rapid progress of civilisation. The latter include reductionist thinking and axiological neutrality typical of natural sciences, increased import_ance of technology, and excessive specialisation combined with poor coordination of diagnostic work-up and treatment or the lack of such coordination. Possible preventive measures include a change in the model of medical education, consisting for instance in the inclusion of humanistic elements and a more holistic view of the patient, as well as a change in the health care model so that the diagnostic work-up and treatment would be coordinated mainly by the primary health care doctor.

An experimental and theoretical investigation on the hyper-viscoelasticity of polyamide 12 produced by selective laser sintering.

Polyamide 12 (PA12) is vastly utilized in many additive manufacturing methods, such as Selective Laser Sintering (SLS), and a better understanding of its mechanical behaviors promotes available knowledge on the behaviors of 3D-printed parts made from this polymer. In this paper, SLS-produced standard tensile specimens are studied under monotonic and cyclic tension tests, as well as stress relaxation experiments, and the obtained force-displacement responses are shown to be consistent with a hyper-viscoelastic material model. This finding is also observed in typical pantographic structures produced by the same manufacturing parameters. To propose a constitutive model for predicting these behaviors, the convolution integral of a strain-dependent function and a time-dependent function is developed where the material parameters are determined with the use of both short-term and long-term responses of the specimens. Numerical results of the presented model for standard test specimens are shown to be in good agreements with the experimental ones under various loading conditions. To prove the capabilities of the proposed model in studying any SLS-produced part, finite element implementation of the constitutive equations is shown to provide numerical results in agreement with the empirical findings for tensile loading of the 3D-printed pantographic structure.

The involvement of angiotensin type 1 and type 2 receptors in estrogen-induced cell proliferation and vascular endothelial growth factor expression in the rat anterior pituitary.

The aim of our study was to examine the involvement of renin-angiotensin system (RAS) in estrogen-induced lactotropes proliferation and vascular endothelial growth factor (VEGF) expression in rat pituitary. The study was performed on Fisher 344 rats underwent 8-day treatment with diethylstilboestrol (DES). The proliferation index (PCNA) and VEGF expression in pituitary sections were estimated using immunohistochemical methods. Treatment with DES increased the number of PCNA-positive cells, VEGF-positive cells, and VEGF-positive blood vessels in pituitary. Stimulatory effect of estrogen on cell proliferation and VEGF expression in blood vessels was attenuated by losartan, PD123319, and captopril. VEGF immunoreactivity in pituitary cells of DES-treated rats was decreased by AT1 antagonist and not changed by AT2 blocker and ACE inhibitor. Our findings suggest the involvement of RAS in DES-induced cell proliferation and VEGF expression in pituitary. Both the AT1 and AT2 receptors appear to mediate the estrogen-dependent mitogenic and proangiogenic effects in rat pituitary.

Angiotensins inhibit cell growth in GH3 lactosomatotroph pituitary tumor cell culture: a possible involvement of the p44/42 and p38 MAPK pathways.

The local renin-angiotensin system is present in the pituitary. We investigated the effects of angiotensins on GH3 lactosomatotroph cells proliferation in vitro and the involvement of p44/42 and p38 MAPK inhibitors in the growth-regulatory effects of angiotensins. Materials and Methods. Cell viability using the Mosmann method and proliferation by the measurement of BrdU incorporation during DNA synthesis were estimated. Results. Ang II and ang IV decreased the viability and proliferation of GH3 cells. Inhibitor of p44/42 MAPK attenuated the effects of ang II on cell viability and proliferation but did not affect the ang 5-8-dependent actions. Inhibitor of p38 MAPK prevented the decrease in the number of GH3 cells in ang-II- and ang-IV-treated groups. Conclusions. The growth-inhibitory effect of ang II is possibly mediated by the p44/42 MAPK. The p38 MAPK appears to mediate the inhibitory effects of both ang II and ang 5-8 upon cell survival.

Comparative analyses of blood flow through mechanical trileaflet and bileaflet aortic valves.

PURPOSE: The primary aim of the present study was to compare the bileaflet and trileaflet aortic valves' performance during uniform blood flow model and boundary conditions. The secondary aim of the study was to determine the effect of Newtonian/non-Newtonian fluid flow assumption on blood flow directly behind the trileaflet valve. METHODS: The geometrical model of the whole system consist of the left ventricle, fragment of the aorta and mechanical valves. A representation of pulsatile flow was obtained by measuring blood flow velocity (Doppler ultrasound examination). We have assumed turbulent blood flow. We considered two blood models, Newtonian and non-Newtonian (Carreau model). The valves' performance was assessed using the reduced stress in the valves, the shear stress in the aortic wall, flow velocity field and the effective orifice area. RESULTS: The maximum von Mises stress for the bileaflet valve leaflets was 0.3 MPa and for the trileaflet valve - 0.06 MPa. The maximum flow velocity for the bileaflet valve was 4.52 m/s for 40° and for the trileaflet valve - 5.74 m/s. Higher shear stress was present in the bileaflet (151.5 Pa) than for the trileaflet valve (49.64 Pa). CONCLUSIONS: The results indicate that central blood jet for the trileaflet valve contributes to more physiological blood flow and decreases the risk of haemolysis. The central flow minimises the risk of leaflet dislocation. In addition, lower stresses extend the durability of the valve. However, the trileaflet valve geometry has also disadvantages, for instance, small peripheral streams or relatively low effective orifice area.

Some aspects related to the indentation-based viscoelastic modelling of trabecular bone tissue.

PURPOSE: The aim of this research was to verify to what extent the shape of an indenter tip influences the final form of the constitutive equation for the trabecular bone. METHODS: Trabecular bone was formulated as a non-linear viscoelastic material with Mooney-Rivlin hyperelastic model to describe the purely elastic response of the bone tissue. Tests of the mechanical properties of the trabecular bone, resected from the femoral head of a 56-year-old patient, were carried out with two types of indenter: the spherical tip of a diameter of 200 µm and pyramid Vickers tip with 136° between plane faces. Tests with both indenters included loading and unloading phases with no hold at peak force and with hold time t = 20 s and were conducted with a maximum load Pmax = 500 mN and loading/unloading rate V = 500 mN/min. RESULTS: The formulated constitutive model describes the trabecula behaviour very well. The model curves match the experimental results in the loading phase, holding period and most of the unloading ramp. The purely viscoelastic material constants are very close in value for both considered tips, but purely elastic constants differ. CONCLUSIONS: The results indicate that the constitutive model based on the indentation with the Vickers tip does not cover the plastic residual deformation. When a viscoelastic response of bone is expected, a model with constants calibrated for the spherical tip should be used, and the other set of parameters values (Vickers tip) when trabeculae may undergo plastic deformation.

Serum testosterone level correlates with left ventricular hypertrophy in older women.

Introduction: Sex hormones may play an important role in age-related cardiac remodeling. However, their impact on cardiac structure and function in females of advanced age still remains unclear. The aim of this study is to evaluate the relationship between sex hormones level and echocardiographic parameters in older women with concomitant cardiovascular diseases. Materials and Methods: The study group included 52 community-dwelling women with mean age 79.5 ± 2.8 years, consecutive patients of an outpatient geriatric clinic. In all the subjects, a transthoracic echocardiogram was performed and serum testosterone, estradiol, follicle-stimulating hormone, luteinising hormone, dehydroepiandrosterone sulphate, and cortisol levels were determined. Results: Testosterone level correlated positively with interventricular septum diastolic dimension (IVSd) (rS=0.293, p<0.05), left ventricular mass index (rS=0.285, p<0.05), E/E' ratio (rS=0.301, p<0.05), and negatively with E' (rS=-0.301, p<0.05). Estradiol level showed a positive correlation with the posterior wall dimension (rS=0.28, p<0.05). Besides, no significant correlations between clinical or echocardiographic parameters and other hormones were observed. Female subjects with diagnosed left ventricular hypertrophy (LVH) (n=34) were characterized by a significantly higher rate of hypertension (p=0.011), higher waist-to-height ratio (p=0.009), higher testosterone level (0.82 vs. 0.48 nmol/L, p=0.024), higher testosterone/estradiol ratio (16.4 vs. 9.9, p=0.021), and received more anti-hypertensive drugs (p=0.030). In a multiple stepwise logistic regression, the best determinants of LVH were the presence of hypertension (OR=6.51; 95% CI 1.62-26.1), and testosterone level (OR= 6.6; 95% CI 1.19-36.6). Conclusions: Higher serum testosterone levels may contribute to pathological cardiac remodeling, especially in hypertensive women. Estradiol, gonadotropins, DHEAS, and cortisol were not related to echocardiographic parameters.

Hormones and depression in the advanced age.

INTRODUCTION: In older people, depression and mental disability are more frequently present than in younger subjects. It is found that depressionis a risk factor for dementia, just as dementia is a risk factor for depression. In turn, both disturbances are known to be influenced by hormones. The present study aimed to see whether the hormonal changes in subjects over 75 years old correlate with the symptoms of depression measured using the Geriatric Depression Scale (GDS). MATERIAL AND METHODS: In a group of patients aged over 75 years, concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), oestradiol, testosterone, dehydroepiandrosterone sulphate (DHEAs), and cortisol were measured in serum with the use of chemiluminescence. The symptoms of depression were estimated by GDS, and the mental functions were assessed by the Mini-Mental State Examination (MMSE). The correlations between the obtained results were estimated by Spearman's test. RESULTS AND CONCLUSIONS: A significant correlation between GDS and MMSE scores was observed in the investigated patients. Some statistically significant correlations concerning cortisol and testosterone with GDS were observed in women, but not in men. On the other hand, no significant correlations between concentrations of FSH, LH, DHEAs, and oestradiol with GDS were noticed. Our data support the role of cortisol (possibly secreted during chronic stress) in the risk of depression. The gender difference in the mechanism of depression and stress in older age could be also hypothesized.

Expression of somatostatin receptor subtypes in primary and recurrent gonadotropinomas: are somatostatin receptors involved in pituitary adenoma recurrence?

OBJECTIVE: Surgical treatment of pituitary macroadenomas often fails because of tumor recurrence after the operation. The causes of tumor recurrence are complex, but one of them may be the high growth potential of the adenoma. As somatostatin receptors mediate antiproliferative, anti-angiogenic and pro-apoptotic actions, it seemed reasonable to investigate their expression in dependence on the adenoma recurrence. METHODS: Samples of primary and recurrent gonadotropinomas excised surgically from patients were examined. This type of pituitary adenomas was chosen because of its relatively high recurrence rate. The adenoma phenotype and expression of somatostatin receptor subtypes 1-5 (SSTR 1-5) were investigated by immunohistochemistry, and the level of SSTR expression was semiquantitatively scored. RESULTS: It was found that the adenomas undergoing the early recurrence have lower expression of SSTR 2A and 3 in comparison to those which did not recur during 5 years lasting observation. On the other hand, the recurrent tumors show higher expression of SSTR 1, 2A, 3 and 5 subtypes than their primary counterparts. CONCLUSIONS: It is hypothesized that SSTR may, at least in part, counteract adenoma recurrence. On the other hand, it can be also presumed that the recurrent gonadotropinomas may be more sensitive to somatostatin analog treatment than primary ones. These hypotheses need to be confirmed in further studies.

Endocrine and metabolic aspects of COVID-19.

The paper presents the theoretical considerations on the role of endocrine and metabolic alterations accompanying COVID-19 infection. These alterations may be presumed on the basis of the following two observations. Firstly, the virus SARS-CoV-2 responsible for the COVID-19 infection uses an important renin-angiotensin system (RAS) element - angiotensin-converting enzyme 2 (ACE2) - as a receptor protein for entry into target cells and, in consequence, disturbs the function of the main (circulating) renin-angiotensin-aldosterone system (RAAS) and of the local renin-angiotensin system localized in different tissues and organs. The binding of SARS-CoV-2 to ACE2 leads to the downregulation of this enzyme and, in the aftermath, to the excess of angiotensin II and aldosterone. Thus, in the later stage of COVID-19 infection, the beneficial effects of ACEI and ARB could be presumed. It is hypothesized that the local RAS dysregulation in the adipose tissue is the main cause of the negative role of obesity as a risk factor of severe outcome of the COVID-19 infection. Secondly, the outcome of COVID-19 strongly depends on the age of the patient. Age-related hormonal deficiencies, especially those of melatonin and dehydroepiandrosterone, may contribute to morbidity/mortality in older people. The usefulness of melatonin and angiotensin converting enzyme inhibitors/angiotensin receptor 1 blockers (the latter only in later phases of the infection) as adjuvant drugs is probable but needs thorough clinical trials.

Gonadotropins at Advanced Age - Perhaps They Are Not So Bad? Correlations Between Gonadotropins and Sarcopenia Indicators in Older Adults.

Many hormones fluctuate during the aging process. It has been suggested that gonadotropins, which increase with age, contribute to the occurrence of many diseases and syndromes in older life, such as cardiovascular diseases, obesity, frailty syndrome and osteoporosis. This study aims to assess the relationship between circulating gonadotropins and other hormones potentially contributing to age-related functional decline and sarcopenia indicators in 39 male and 61 female community-dwelling seniors, mean age 80 years. According to the definition developed by the second European Working Group on Sarcopenia in Older People (EWGSOP2), the following indicators of the sarcopenia were assessed: bioimpedance-measured body composition, gait speed, handgrip strength, timed up and go test (TUG), chair stand test, Short Physical Performance Battery (SPPB). Blood levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, testosterone, dehydroepiandrosterone sulphate (DHEAS) and cortisol were also measured. In the men, FSH and partially LH correlated positively with muscle mass percentage, gait speed, handgrip strength and SPPB, and negatively with percent body fat. Additionally, testosterone and DHEAS correlated negatively with the percentage of fat mass in men. Whereas in the women, FSH and LH were mainly negatively associated with body mass and adipose tissue measures. Cortisol did not show any relationship with the examined indicators. The study shows that the indicators of sarcopenia are strongly associated with levels of gonadotropins, sex hormones and DHEAS, especially in older men. The obtained results, after being confirmed in a larger group, may modify prevention and treatment strategies of sarcopenia.

Plurihormonality of pituitary adenomas in light of immunohistochemical studies.

INTRODUCTION: Plurihormonality of pituitary adenomas can be defined as the ability of an adenoma to express more than one pituitary hormone. The application of immunohistochemistry to diagnose surgically removed pituitary tumours revealed that a great number of pituitary adenomas are in fact plurihormonal. However, data on the incidence and the clinical relevance of the pituitary adenoma plurihormonality are still scarce and controversial. MATERIAL AND METHODS: Hundred fifty-five pituitary adenomas, surgically removed, were studied immunohistochemically with the antibodies against pituitary hormones or their subunits. Additionally, 40 adenomas were immunostained with Ki-67 antibody to evaluate the proliferative potential. RESULTS: According to the World Health Organization (WHO) recommendations, we did not consider tumours expressing both FSH and LH (gonadotropinomas) or somatoprolactinomas expressing both GH and prolactin as plurihormonal. Even with this limitation, plurihormonality was found to be a frequent finding in both hormonally active and clinically non-functioning pituitary adenomas. It was shown that over one-third (36.1%) of the investigated adenomas expressed more than one hormone. Plurihormonality, especially that which is connected with co-expression of ACTH, seems to be more frequent in the recurrent tumours. Plurihormonal adenomas also possess higher Ki-67 indices, as compared to monohormonal tumours. CONCLUSIONS: Plurihormonality is a frequent phenomenon in both hormonally active and clinically non-functioning pituitary adenomas. It also seems to predict a higher risk of tumour recurrence. (Pol J Endocrinol 2010; 61 (1): 63-66).

Does the response of GH-secreting pituitary adenomas to octreotide depend on the cellular localization of the somatostatin receptor subtypes SSTR2 and SSTR5?

INTRODUCTION: The immunohistochemical examination of somatostatin receptor (SSTR) subtypes expression in different endocrine tumours, including pituitary adenomas, revealed membranous or cytoplasmic distribution of SSTR1-5. Currently used long-acting somatostatin analogue octreotide prefers SSTR2 and SSTR5 subtypes. In an earlier study a positive correlation between the summarized score of SSTR2A + SSTR2B expressions and growth hormone (GH) response to octreotide administration was found, independently of receptor distribution within the cell. In this study we searched for the relationship between the GH inhibitory response to acute octreotide administration and SSTR2A, SSTR2B, and SSTR5 cellular localization. MATERIAL AND METHODS: Thirteen acromegalic patients underwent a test of acute administration of octreotide before surgery. The drop in GH was defined as the percentage of the basal value. The pituitary adenomas from these patients were immunostained to determine the hormonal phenotype and expression of SSTR subtypes. The subcellular distribution pattern of SSTR subtypes - membranous or cytoplasmic - was determined. RESULTS: In the majority of specimens, cytoplasmic localization of receptor subtypes was observed, although membrane or mixed cytoplasmicmembranous localized immunopositivity also occurred. The drop in GH after octreotide administration varied between 57.1-96.7% (mean 82.1%). Among the patients with the cytoplasmic localization of SSTR5, the decrease in GH was significantly higher (92.0 +/- 7.0%). A tendency towards the higher response in patients with cytoplasmic localization of SSTR2A and 2B was also observed (86.8% and 87.0%, respectively). CONCLUSIONS: It seems that cytoplasmic localization of SSTR5, SSTR2A, and SSTR2B is connected with enhanced GH inhibition after octreotide administration. It is possible that this somatostatin analogue alters the localization of subtypes SSTR2A and SSTR2B through the receptor internalization. As a consequence, the SSTR-immunopositivity in cell cytoplasm is increased. The cytoplasmic but not the membranous localization is connected with the higher responsiveness to the octreotide in somatotropinomas.

Possible role of gonadotropin excess in age-related diseases - return to the old hypothesis in the light of current data.

The paper presents the evaluation of a hypothesis assuming that the elevated levels of gonadotropins which occur physiologically in older persons are involved by their direct extra-gonadal action in the pathogenesis of age-related disorders. The data on the possibilities of the direct action of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and their possible deleterious effects in the brain, bone, cardiovascular system and cancer in older persons are reviewed. A proposal of a new approach to the hormonal prevention treatment of age-related disorders (suppression of gonadotropins by means of gonadotropin releasing hormone analogs) is discussed.

Immunohistochemical detection of prolactin in clinically non-functioning pituitary adenomas.

INTRODUCTION: Approximately one third of pituitary adenomas are manifested neither by specific symptoms of hormone overproduction nor by elevated blood levels of pituitary hormones. However, these tumours, diagnosed before surgical intervention as clinically non-functioning pituitary adenomas (CNFPAs) express in majority different pituitary hormones, as can be revealed by means of immunohistochemical examination. One of the pituitary hormones which may be expressed in CNFPAs is prolactin (PRL) but the clinical and pathological data on this condition are very scarce. MATERIAL AND METHODS: Sixty two pituitary adenomas, diagnosed before surgery as CNFPAs, were immunoassayed with antibodies against PRL, growth hormone (GH), luteinizing hormone (LH), follicle stimulating hormone (FSH), thyrotropin (TSH), alpha subunit (alpha-SU), corticotropin (ACTH) and dopamine receptor type 2. In a proportion of the patients the presurgical concentrations of insulin-like growth factor 1 (IGF-1) were estimated by means of enzyme-amplified chemiluminescence assay. RESULTS: Twenty-three (37.1%) of the examined CNFPAs presented the positive immunoreaction with anti-PRL antibody. Most cases concerned women. Only in two cases (one woman and one man), PRL was the unique hormone expressed in the tumour. In the remaining adenomas PRL immunopositivity was accompanied by GH expression - 17, LH or free bLH - 13, FSH - 2, free a subunit - 4 or by ACTH - 5 tumours. Seven (30.43%) of them were recurrent in comparison with 12.8% PRL-immunonegative recurrent CNFPAs. Dopamine receptors were positively immunostained in all the investigated PRL-immunopositive and all PRL-immunonegative adenomas. CONCLUSIONS: Our data confirm the observations that monohormonal silent prolactinomas are very rare but frequently silent PRL often co-expressed with GH or LH. Although in the whole population of patients with CNFPAs both sexes are equally represented, in the case of silent prolactinomas the female sex is prevalent. The observation of the higher rate of recurrent tumours within PRL-immunopositive adenomas versus PRL-immunonegative CNFPAs has to be confirmed on the larger material.

Are physical and mental abilities of older people related to gonadotropins and steroid hormones levels?

BACKGROUND: Aging is characterized by deep alterations of hormone secretion. In majority, hormone secretion, except gonadotropins, undergoes a pronounced decrease which is thought to contribute to the progression of aging. The recent data indicate that gonadotropin excess may also by itself influence the aging process. The aim of the present study was to investigate the relations between gonadotropins and steroid hormones with physical and mental abilities of older people. MATERIAL AND METHODS: In a group of patients aged over 75 years, concentrations of FSH, LH, estradiol, testosterone, DHEAs and cortisol were measured. The mental ability was estimated by MMSE and CDT and the physical ability by TUG and SPPB tests. RESULTS AND CONCLUSIONS: The positive correlation between SPPB scores and FSH and the negative correlations of SPPB with LH/FSH ratio were observed in men. The correlation of TUG scores and estradiol levels was also noted in men. The positive correlation between CDT scores and FSH in women and the negative correlation between CDT and LH/FSH ratio in men were found. The correlation between the results of CDT and cortisol levels in men was also observed. Thus, we did not confirm the simple deleterious effect of gonadotropins on cognitive abilities. FSH and LH seem exert different (antagonistic?) effects on cognitive functions, but this hypothesis needs further studies.

Angiotensin receptors in hormone-independent prostate cancer cell line DU145: presence of two variants of angiotensin type 1 receptor.

BACKGROUND: Recently, the involvement of the renin-angiotensin system in the proliferation of prostate cancer has been suggested. There is increasing evidence that angiotensin II receptor type 1 (AT1) is expressed in a variety of cancer cells and tissues and may have a role in tumor growth, angiogenesis, and invasive activity of malignant lesions in vivo. The implications of data referring to an angiotensin receptor in hormone-independent human prostate cancer DU145 cells are unclear. Angiotensin II has been shown to inhibit the proliferation of DU145 cell lines. However, it is known that AT1 stimulates cell proliferation and that angiotensin II receptor type 2 (AT2) induces apoptosis and inhibits cell proliferation. MATERIAL/METHODS: The aim of our study was to investigate, by means of immunohistochemical and reverse transcriptase polymerase chain reaction assays, the type of angiotensin II receptor that is present in DU145 cells. RESULTS: In DU145-derived complementary deoxyribonucleic acid (cDNA), a polymerase chain reaction assay revealed 2 AT1-specific PCR products (93 bp and 126 bp). DU145-derived cDNA did not reveal AT2 expression at a level sufficient for detection by PCR. In cultured cells, immunohistochemical testing revealed a positive reaction in cultures immunostained with anti-AT1 antibody but not in those immunostained with AT2 antibody. CONCLUSIONS: The inhibitory effect of angiotensin II on the proliferation of DU145 cells is exerted via AT1. It is possible that presence of 2 variants of AT1 in that cancer cell line is essential to produce the biological effects of angiotensin.

Luzindole but not 4-phenyl-2- propionamidotetralin (4P-PDOT) diminishes the inhibitory effect of melatonin on murine Colon 38 cancer growth in vitro.

OBJECTIVE: Our earlier studies have shown that MLT exerts the inhibitory effect on murine cancer via membrane and nuclear receptors. We have found that the antagonist of MT1 receptors does not diminish the antiproliferative effect of MLT on Colon 38 cells, and the contribution of MT2 receptors has been suggested to be responsible. Therefore, in the present study we have examined the influence of the 4-phenyl-2-propionamidotetralin (4P-PDOT), which is a selective antagonist of MT2 membrane receptor, and luzindole - an antagonist of both membrane receptors, on an oncostatic action of MLT. MATERIALS AND METHODS: The murine cancer cell line Colon 38 was used in the experiments. In 48 hrs cell culture the effects of MLT, 4P-PDOT and luzindole administered alone and MLT applied jointly with either 4P-PDOT or luzindole were examined. The growth of cancer cells was assessed using the modified colorimetric Mosmann method. RESULTS: Melatonin at both examined concentrations (10-7, 10-9 M) significantly decreased the viability of cancer cells. The selective antagonist of MT2 membrane receptor, namely 4P-PDOT and luzindole applied separately did not have an effect on the growth of Colon 38 cells. The addition of 4P-PDOT to MLT did not change the inhibitory effect of MLT, whereas luzindole given together with MLT diminished, but failed to block totally, the oncostatic properties of MLT. CONCLUSIONS: The obtained data and our previous studies conducted on Colon 38 cancer indicate that membrane melatonin receptors are not indispensable to the oncostatic action of melatonin and thus other pathways such as nuclear signaling and receptor-independent mechanism may be also involved.