Ochratoxin a content of urine samples of healthy humans in Hungary

The ochratoxin A (OTA) content of urine samples from 88 healthy humans living at five settlements in three counties of Hungary was determined by immunoaffinity column cleanup and high-performance liquid chromatography (HPLC). OTA was detected in 61% of the samples in an average concentration of 0.013 ng/ml (range: 0.006-0.065 ng/ml). OTA concentrations measured in urine samples from men and women were not significantly different. The OTA concentration of samples from Heves county was significantly (t-test; p < 0.003) higher than that of samples from Hajdú-Bihar and Somogy counties. The regional differences in OTA concentration of urine samples indicate regional differences in the OTA exposure of the human population. Further studies are necessary to determine the cause of the regional differences in the OTA intake. The studies allow us to conclude that the OTA intake of the majority of the Hungarian population is low (< 1 ng/kg of body weight per day) but a certain part of the rural population may take up higher levels of OTA.

[Nutritional health aspects of mycotoxins]

Mycotoxins produced by mould fungi can enter into the human food chain directly through foods of plant origin (cereal grains), consumer goods (coffee and bear) and indirectly through foods of animal origin (kidney, liver, milk and eggs). Mycotoxins occur in small amount in the foods; however their continuous intake even in microdoses can result in accumulation in the organism. Synergic effects of the mycotoxins as well as their possible additive multi-toxic effects seem to be especially dangerous. Mycotoxin problems are very important in Hungary because these natural toxins occur mainly in those cereals (e.g. wheat, maize) that amount to high proportion of the sowing area in Hungary and provide the main foods to the inhabitants. Public health risks of the toxins accumulating in the human and animal bodies during the long term consumption of the mycotoxins containing foods--even in small doses--have not been evaluated yet as thoroughly as their importance would require. However, there are more and more direct and indirect expressions of the danger resulting from the toxins. The most frequently observed human health effects are carcinogen effects (aflatoxin, ochratoxin A, fumonisins, patulin); effects causing developmental abnormalities (zearalenon, ochratoxin); effects harmful to the reproduction (zearalenon, and trichotecenes), effects decreasing the resistance; immunosuppressive effects (trichotecenes), and effects causing injury of the nervous system (ochratoxin A, fumonisins). Prevention of the injury of the health caused by mycotoxins can be completed by joint and integrated activity of the various disciplines only and requires a comprehensive interdisciplinary cooperation. This paper gives a discussion on health injuring effects of the most frequently occurring mycotoxins that are very important from human health aspects in Hungary; on their occurrence in the foods and on their human risk.

Cavernous transformation of the portal vein causing jaundice, presenting in the form of Wilson's disease

The following is a case review of portal vein cavernous malformation presenting with intermittent cholestasis and jaundice in a 4 year old child. Correct assessment was supported by radiology, later laparoscopy, yet hindered by histopathology representative Wilson's disease and elevated urinary copper excretion. During surgical procedure the stenosis of the common bile duct secondary to extremely dilated portal vein reticulation was solved by Roux-en-Y choledochojejunostomy. After a one-year follow up the child remains asymptomatic.

Turbinate atrophy evaluation in pigs by computed tomography

Computed tomography (CT), a non-invasive visualisation technique was applied for imaging the bony structures of the nasal cavity of pigs, and compared to the traditional scoring system of turbinate atrophy in swine. Twenty-three 27-week-old pigs representing various stages of turbinate atrophy were used. Nasal structures were visually scored on CT scans and transversal cuts of the noses at the level of the first upper premolar teeth using the same scoring system in both cases. A tissue/air area ratio was also determined based on density differences. A highly significant correlation was found between visual scoring of CT images and transversal cuts of pig noses (r = 0.98, p < 0.0001) as well as between visual scoring of CT images and tissue/air area ratio determination (r = -0.82, p < 0.0001).

Residue formation of fumonisin B1 in porcine tissues

The residues derived from the uptake of fumonisin B1, a toxic metabolite of Fusarium verticillioides frequently occurring in corn and corn products, were determined in growing pigs. After oral administration of 100 mg FB(1)/animal/day for 5-11 days, serum, bile, lung, liver, kidney, brain, spleen, pancreas, heart, muscle, eye, and fat samples were collected immediately and analysed by LC-MS. The highest values were measured in kidney (833 +/- 1329 microg kg(-1), mean +/- SD), liver (231 +/- 163 microg kg(-1)), lung (170 +/- 311 microg kg(-1)) and spleen (854 +/- 2212 microg kg(-1)). Muscle contained 26 +/- 41 microg kg(-1), while in fat only 2 +/- 3 microg kg(-1) were traceable. Despite the potential accumulation over extended feeding periods as well as the large variations in the residue formation of FB(1), a carry-over in edible tissues from swine was considered not to be of toxicological relevance.

Effect of dietary fumonisin B1 on certain immune parameters of weaned pigs

Only few data are available on the effect of fumonisins on the immune response. The aim of the present study was to examine whether dietary fumonisin B1 (FB1) has any effect on the humoral and cellular immune response in weaned pigs, depending on the dose and the time of toxin exposure. Fusarium moniliforme fungal culture was added to the experimental animals' diet to ensure an FB1 intake of 1, 5 and 10 ppm (first experiment) or 100 mg per animal per day (second experiment). The control animals were fed a toxin-free diet. In order to determine the immune response, the animals were vaccinated against Aujeszky's disease with inactivated vaccine (Aujesping K, Phylaxia-Sanofi, Budapest, Hungary). Specific and nonspecific in vitro cellular immune response was measured by the lymphocyte stimulation test (LST) induced by PHA-P, Con A, LPS and inactivated suspension of the Aujeszky's disease virus. Humoral immune response, e.g. specific antibody titre, was measured by the virus neutralisation (VN) test. None of the immunological parameters examined showed significant differences between groups. It could be concluded that fumonisin B1 had no significant effect on the humoral and cellular specific and nonspecific immune response when fed in a high dose (100 mg/animal/day for 8 days) or in a low concentration even for a longer period (1, 5 and 10 ppm for 3-4 months).

Role of tumour necrosis factor-alpha in insulin resistance during normal pregnancy

OBJECTIVE

Role of tumour necrosis factor-alpha (TNF-alpha) was studied in insulin resistance during pregnancy.

STUDY DESIGN

Serum TNF-alpha (ELISA) and fasting C-peptide (Cp) (RIA) concentrations were measured in 40 healthy pregnant women (15, 12 and 13 of them in the 1st, 2nd and 3rd trimesters, respectively) and in 25 healthy non-pregnant women in a case-control study.

RESULTS

TNF-alpha (X+/-S.D.: 5.33+/-0.46 pg/ml) and Cp levels (3.37+/-1.30 ng/ml) were significantly higher in the 3rd trimester as compared with matched healthy controls (TNF: 4.07+/-0.26, Cp: 1.05+/-0.36) and to the pregnant women in 1st (TNF: 4.04+/-0.26, Cp: 1.34+/-0.59) and 2nd (TNF: 4.35+/-0.32, Cp: 1.11+/-0.35) trimesters. Significant positive linear correlation was calculated among TNF-alpha, Cp, Cp/blood glucose ratio (indirect parameters of insulin resistance) and body mass indexes (BMIs) of pregnant women (P<0.01).

CONCLUSION

TNF-alpha may contribute to the insulin resistance during the course of normal pregnancy.

The pathophysiological influence of leptin and the tumor necrosis factor system on maternal insulin resistance: negative correlation with anthropometric parameters of neonates in gestational diabetes

The contribution of the tumor necrosis factor (TNF) system and leptin was studied in insulin resistance and neonatal development during the course of normal pregnancy and gestational diabetes mellitus (GDM). Thirty patients with GDM and their neonates (n = 30), 35 healthy pregnant women (15 in the first, nine in the second and 11 in the third trimester) and their neonates (n = 20), and 25 healthy matched non-pregnant women participated in the study. Significantly elevated levels of maternal TNF-alpha, sTNF receptor (R)-1 and R-2, leptin (detected by enzyme-linked immunosorbent assay) and fasting C-peptide (measured by radioimmunossay and raised body mass index (BMI) were found in GDM patients and in the third trimester of normal pregnancies. TNF-alpha, sTNFR-2, C-peptide, leptin concentrations and BMI positively correlated with each other in GDM. An inverse relationship between the body length, head circumference and body weight of the newborns, and maternal TNF-alpha, leptin and C-peptide concentrations was shown in GDM. In healthy pregnancies the maternal serum leptin level was in a negative linear correlation with the head circumference of the newborns. In conclusion, increased TNF-alpha and leptin levels may contribute to insulin resistance in GDM and in the third trimester of normal pregnancy and may negatively influence the anthropometric parameters of the newborns.

Increased frequency of the C3*F allele and the Leiden mutation of coagulation factor V in patients with severe coronary heart disease who survived myocardial infarction

The aim of the present study was to compare the frequencies of the F allele of C3 complement component and the Leiden mutation of coagulation factor V in patients with severe coronary heart disease (CHD) who survived myocardial infarction (MI; group A), and those who had no MI in their case history (group B). We have determined the C3 allele frequencies by electrophoresis, and Leiden mutation by PCR in 338 patients with severe CHD and in 490 and 523 healthy controls, respectively. The C3*F allele frequency was significantly (p = 0.006) higher in group A (0.213) that in group B (0.132). A significant (p = 0.045) difference was found between < or = 60-year group A (0.077) and group B (0.029) patients in the frequency of Leiden mutation. These findings indicate that the C3*F allele and the Leiden mutation may be associated with an increased risk of developing myocardial infarction in CHD patients.

Role of TNF-alpha and its 55 and 75 kDa receptors in bronchial hyperreactivity

The pathophysiological role of the tumour necrosis factor (TNF) system was studied in adults (n=37) and children (n=43) non asthmatic offspring of asthmatic parents with and without bronchial hyperreactivity proved by methacholine airway challenge test. SerumTNFalpha and its soluble receptors (sTNF-R1 and R2) were determined by enzyme-linked immunosorbent assay (ELISA). Significantly elevated TNFalpha (adults: mean +/- SD=5.18 +/- 0.87 pg ml(-1), children: 5.08 +/- 1.78) vs. non-hyperreactives (adults: 4.12 +/- 0.43, P < 0.0001, children: 3.75 +/- 0.68, P=0.0084), sTNF-R1 (adults: 144 +/- 0.31 ng ml(-1), children: 1.30 +/- 0 25 vs. adults: 1.21 +/- 0.14, P=0.0305, children: 1.13+/-0.11 ng ml(-1), P=0.0042) and sTNF-R2 (adults: 0.85 +/- 0.40ng ml(-1), children: 0.70 +/- 0.46 vs. adults: 0.56 +/- 0.56 P=0.0084, children: 0.33 +/- 0.17, P=0.0048) and decreased sTNF-R1/R2 ratio (adults: mean +/- SD=0.96 +/- 0.73, children: 2.85 +/- 2.06 vs. adults: 4.82+/-3.40, P=0.0272, children: 4 42 +/- 2 30, P=0.0167) were measured in patients with bronchial hyperreactivityThe provocation doses of methacholine causing a 20% reduction (PD20) in forced expiratory volume in 1 sec (FEV1) were found to be in a significant negative linear correlation with TNFalpha sTNF-R1 and R2 levels in hyperreactive adults and with TNFalpha, sTNF-R2 in hyperreactive children. TNFalpha correlated significantly with its receptors both in hyperreactive adults and children and with the body mass index (BMI) values of adults. The TNF system may contribute to the pathophysiology of bronchial hyperreactivity Altered shedding of sTNF-R1 seems to occur in hyperreactive patients.

Kinetic resolution of a conformational transition and the ATP hydrolysis step using relaxation methods with a Dictyostelium myosin II mutant containing a single tryptophan residue

The fluorescence emission intensity from a conserved tryptophan residue (W501) located in the relay loop (F466 to L516) of the Dicytostelium discoideum myosin II motor domain is sensitive to ATP binding and hydrolysis. The initial binding process is accompanied by a small quench in fluorescence, and this is followed by a large enhancement that appears coincident with the hydrolysis step. Using temperature and pressure jump methods, we show that the enhancement process is kinetically distinct from but coupled to the hydrolysis step. The fluorescence enhancement corresponds to the open-closed transition (k(obs) approximately 1000 s(-1) at 20 degrees C). From the overall steady-state fluorescence signal and the presence or absence of a relaxation transient, we conclude that the ADP state is largely in the open state, while the ADP.AlF(4) state is largely closed. At 20 degrees C the open-closed equilibria for the AMP.PNP and ADP.BeF(x) complexes are close to unity and are readily perturbed by temperature and pressure. In the case of ATP, the equilibrium of this step slightly favors the open state, but coupling to the subsequent hydrolysis step gives rise to a predominantly closed state in the steady state. Pressure jump during steady-state ATP turnover reveals the distinct transients for the rapid open-closed transition and the slower hydrolysis step.

Anti-cholesterol antibodies (ACHA) in patients with different atherosclerotic vascular diseases and healthy individuals. Characterization of human ACHA

In animal experiments the protective role of anti-cholesterol antibodies (ACHA) in the development of atherosclerosis has been demonstrated. Despite the fact that ACHA are present in the serum of healthy humans, no data on the occurrence of these antibodies in human diseases are available. We determined serum concentrations of IgG type ACHA by an enzyme immunosorbent assay in 600 patients with atherosclerotic vascular diseases (86 patients with peripheral occlusive atherosclerosis, 146 patients with cerebrovascular diseases, 341 patients with severe coronary heart disease (CHD) who received aorto-coronary by-pass, 27 patients with myocardial infarction who did not undergo by-pass operation), in 57 patient controls (complaints of CHD, without coronarographic alterations) and in 218 healthy individuals. ACHA were present in the sera of all persons tested. No serum cofactor is needed for the binding of human ACHA to solid phase cholesterol, binding can be inhibited dose-dependently by LDL and even more strongly with LDL/VLDL preparations purified from human serum. ACHA levels were found to be considerably lower in patients with peripheral occlusive atherosclerosis and cerebrovascular diseases compared with the levels in healthy individuals. By contrast, the ACHA levels of patients with CHD were considerably higher. No differences in the IgG subclass distribution and binding efficiency of ACHA in the sera of CHD patients and controls were found. Thus, our present findings indicate that both low and high ACHA production may be associated with different atherosclerotic vascular diseases.

[Synthesis and analytical characterization of the dansyl derivatives of 6,14-ethenomorphinans]

The synthesis of the dansyl derivatives of the pharmacologically important 6,14-ethenomorphinans has not been reported. The authors realized the preparation of the dansyl derivatives (2a-i) of some 20-alkyl(aralkyl)-orvinols (1a-i). The authors unequivocally proved the structure of the parent compounds, and their dansyl derivatives. The authors also investigated certain analitical characteristics (thin-layer chromatography, UV-spectral data and reversed-phase HPLC purity tests) for the detection if necessary of these compound in biological fluid. Namely, due to the fluorescent properties of the dansyl derivatives, the sensitivity and selectivity of the analytical determinations of the parent compounds are significantly enhanced.

Elevated serum TNF-alpha level as a link between endothelial dysfunction and insulin resistance in normotensive obese patients

AIMS

The aim of the study was to analyse the role of tumour necrosis factor-alpha (TNF-alpha) in insulin resistance and endothelial dysfunction in patients with different types of obesity.

PATIENTS AND METHODS

Fasting serum TNF-alpha immunoreactive concentration (enzyme-linked immunosorbent assay, ELISA) and bioactivity (L929 cell cytotoxicity assay), endothelin-1 and C-peptide levels (radioimmunoassay, RIA) were measured in 15 patients with android- and 13 patients with gynoid-type obesity and 15 lean healthy controls with normal glucose tolerance and blood pressure.

RESULTS

Significantly (P<0.01) higher TNF-alpha concentration (8.92 +/- 0.44 pg/ml) and bioactivity (3.12 +/- 0.48 U/ml) were found in patients with android obesity as compared to patients with gynoid obesity (7.01 +/- 0.30 pg/ml, 0.97 +/- 0.11 U/ml) and to the lean controls (6.88 +/- 0.26 pg/ml, 0.88 +/- 0.08 U/ml). Serum endothelin-1 (5.38 +/- 0.30 pg/ml) and C-peptide levels (4.82 +/- 0.71 ng/ml) were also significantly higher (P < 0.01) in patients with android-type obesity than in controls (3.89 +/- 0.43 pg/ml, 1.46 +/- 0.25 ng/ml, respectively). In patients with gynoid-type obesity, only the C-peptide levels proved to be significantly higher (2.84 +/- 0.29 ng/ ml). Endothelin-1 levels, although were found to be slightly higher, did not differ statistically from in controls (4.56 +/- 0.31 pg/ml). There were significant positive linear correlations only in patients with android-type obesity between TNF-alpha, body mass index (BMI), serum endothelin-1 and C-peptide levels.

CONCLUSIONS

TNF-alpha may be one of the factors contributing to insulin resistance and vascular dysfunction in patients with android obesity.

Elevated serum tumor necrosis factor-alpha concentrations and bioactivity in Type 2 diabetics and patients with android type obesity

The role of tumor necrosis factor-alpha in insulin resistance has been studied in 59 patients with Type 2 diabetes, 28 with android type obesity and 35 healthy lean controls. Immunoreactive concentrations and bioactivity of serum tumor necrosis factor-alpha have repeatedly been determined in 8 weeks intervals for 12 months, five times per patients, by using ELISA and L929 cell cytotoxicity bioassay. Significantly higher immunoreactive tumor necrosis factor-alpha concentrations and bioactivity have been found in both, the Type 2 diabetic and obese groups as compared to the healthy persons. Tumor necrosis factor-alpha concentrations and bioactivity have showed a significant positive linear correlation with the elevated basal serum C-peptide levels and body mass indexes in both groups of patients. According to these data the cytokine might play a role in insulin resistance in obesity as well in Type 2 diabetes.

Direct anticancer activity of gonadotropin-releasing hormone-III

In previous studies GnRH-III, a variant of the hypothalamic neurohormone GnRH, was isolated from the brain of the sea lamprey and structurally characterized. GnRH-III is a hypothalamic neurohormone in both female and male sea lampreys. In the present work biological activities of GnRH-III in mammalian systems were examined. In superfused rat pituitary cells, GnRH-III at 1 nM to 100 nM neither induced LH-secretion nor inhibited the LH-secretion elicited by native GnRH and elicited LH release only at 1 microM. At high dose (500 microg/day) in vivo, GnRH-III behaved as a GnRH agonist, though, it was 1000-fold less active than ovurelin. The in vitro and in vivo results were in good agreement in showing that GnRH-III is only a weak agonist of the endocrine activity of GnRH. GnRH-III specifically bound to receptors on cancer cells and recognized not only the high-, but also the low-affinity binding sites. GnRH-III significantly suppressed growth of human cancer cells which have GnRH receptors. The inhibitory effect of GnRH-III on growth of cancer cells was specific and direct since the peptide did not have endocrine activity in the concentration range found to be effective in anticancer assays. GnRH-III inhibited equally the growth of ER-positive and -negative breast and TeR-positive and negative prostate cells.

Pancreatic leiomyosarcoma. Case report with immunohistochemical and flow cytometric studies

A leiomyosarcoma originating from the pancreas of a 57-year-old man is presented. A 6x5x4 cm tumour was located in the head region, and the patient underwent surgical palliation. Immunohistochemical studies excluded an epithelial origin; a myogenic origin was suggested by strong vimentin and smooth muscle actin positivity. Flow cytometric analysis revealed an aneuploid pattern (DNA index: 1,561). The patient died with widespread metastases 7 month after the operation.

[Incidence of familial defective apolipoprotein B-100 in cases of patients diagnosed with familial hypercholesterolemia]

Familial Hypercholesterolemia (FH) and Familial Defective Apolipoprotein B-100 (FDB) are monogenic, autosome, dominantly inherited diseases appearing as type II/a primary hypercholesterolemia. The frequency of the heterozygositic forms is 1:700-1:500 in European population. Both forms of hypercholesterolemia causes early onset coronary heart diseases (CHD). According to the recommendations of the international MED-PED program (Make Early Diagnoses--Prevent Early Death), we found 73 FH cases and their 377 first relatives (parents, siblings, children) were also assessed. 156 patients were diagnosed clinically FH (131 alive and 25 deceased), and 31.8% of the males and 32.4% of females suffered from early onset CHD. One family with FH consists of 5.46 members on the average and there are 2.39 FH patients in one family. In our FH cohort four patients with FDB (R3500Q mutation) were diagnosed with allelspecific PCR, and the mutation was detectable also in 9 cases out of 11 living family members. The plasma total cholesterol level of the FDB patients--especially at younger age--was very close to the normal values, which is in contrast to the findings in FH patients. Nevertheless, FDB can be one of the independent causes of the early onset CHD. Therefore, in families with high frequency of cardiovascular diseases the R3500Q mutation has to be considered.

Electrochemical stimulation of the median eminence evokes FSH but not LH release after LHRH antagonist treatment in vivo and in vitro

Experimental data suggest that a follicle stimulating hormone-releasing factor (FSH-RF) distinct from luteinizing hormone-releasing hormone (LHRH) exists. In the present study, we investigated, in short-term ovariectomized (OVX) rats, whether FSH-RF(s) can be released from nerve terminals by electrochemical stimulation (ECS) of the median eminence. To prevent the effect of LHRH liberated by ECS, 100 microg of a potent LHRH antagonist (MI-1544) was administered to one group of OVX rats 60 min before ECS. Two groups of OVX rats were used as controls. One group was treated with the solvent of the LHRH antagonist 60 min before the ECS; the other group received sham-ECS only. In-vitro experiments using a hypothalamus-pituitary coperifusion system were also performed to investigate the direct effect of ECS of the median eminence on LH and FSH release from pituitary cells. ECS in vivo induced 4.6-fold (P<0.01) and 10.2-fold (P<0.01) elevation of serum LH concentration, measured by RIA at 10 min and 60 min after ECS, respectively. Serum FSH concentrations increased 1.35-fold at 10 min (P<0.01) and 1.50-fold at 60 min (P<0.01) after ECS, compared with sham-stimulated controls. Administration of LHRH antagonist attenuated the ECS-induced release of LH by 44% at 10 min and prevented it entirely at 60 min after ECS. However, the ECS-induced release of FSH was not modified by the antagonist at 10 min and was diminished by only 17% at 60 min after ECS, compared with solvent-treated and stimulated controls. Immunohistological examination of the hypothalami showed that LHRH-immunoreactivity was depleted in the region of ECS. In the study in vitro, substances released from the fragments of mediobasal hypothalami bearing ECS in the median eminence induced significant release of both LH and FSH, and the induced release of LH, but not FSH, was prevented by the LHRH antagonist. The present study suggests that FSH-releasing factor(s) different from LHRH can be released from the median eminence and that a significant portion of FSH secretion is independent of the control of LHRH.

Synthesis and biological evaluation of cytotoxic analogs of somatostatin containing doxorubicin or its intensely potent derivative, 2-pyrrolinodoxorubicin

To create cytotoxic hybrid analogs of somatostatin (SST), octapeptides RC-160 (D-Phe-Cys-Tyr-D-Trp- Lys-Val-Cys-Trp-NH2) and RC-121 (D-Phe-Cys-Tyr-D-Trp- Lys-Val-Cys-Thr-NH2) were linked to doxorubicin (DOX) or its superactive derivative, 2-pyrrolino-DOX (AN-201). The conjugation was performed by coupling N-9-fluorenylmethoxycarbonyl (N-Fmoc)-DOX-14-O-hemiglutarate or 2-pyrrolino-DOX-14-O-hemiglutarate to the amino terminus of [Lys(Fmoc)5]RC-160 yielding AN-163 and AN-258, respectively, after deprotection. The respective cytotoxic conjugates of RC-121 (AN-162 and AN-238) were prepared similarly. In vitro tests on human cancer cell lines-MKN-45 gastric cancer, MDA-MB-231 breast cancer, PC-3 prostate cancer, and MIA PaCa-2 pancreatic cancer-demonstrated that the antiproliferative activity of the cytotoxic radicals in these conjugates was virtually retained. In H-345 human small cell lung carcinoma cell line, conjugates of RC-121 preserved the cytotoxic activity of their radicals, but the hybrids with RC-160 showed approximately 10 times lower activity. The ability of the carriers and the hybrids to inhibit the binding of 125I-labeled RC-160 to receptors for SST on rat pituitary membrane preparation was also determined. The cytotoxic conjugates inhibited 50% of the specific binding of the radioligand in the nanomolar concentration range (IC50 < 80 nM). When SST-like activities of AN-238 and its carrier, RC-121, were compared in the rat pituitary superfusion system, both compounds were found to suppress a stimulated growth hormone release at nanomolar concentrations. Preliminary studies in animal models of breast and prostate cancers showed that AN-238 is less toxic than AN-201 and more potent in inhibiting tumor growth. These highly active cytotoxic analogs of SST have been designed as targeted antitumor agents for the treatment of various cancers expressing receptors for SST octapeptides.

Synthesis of GnRH analogs having direct antitumor and low LH-releasing activity

New chicken I GnRH agonists and antagonists have been synthesized and tested for their biological activities. The common feature of these analogs was that the molecules had a beta-L-aspartyl residue inserted in position 6. The agonist bound to the pituitary still had low endocrinological activity. On the other hand, it exhibited direct antitumor effect in in vitro assays. The endocrinological activity of the antagonist was low; however, it showed potent, direct antitumor activity. These observations might lead to the development of new GnRH analogs with selective antitumor effect.

Inhibition of GH release of rats by new potent antagonists of growth hormone-releasing hormone (GH-RH)

Biological activity of a new series of potent GH-RH antagonists containing formyl or phenylacetyl group at the N-terminus of the sequence [D-Arg2,Phe(4-Cl)6,Nle27]hGH-RH(1-29)NH2, as well as various substitutions in positions 8, 15, or 28, and in some cases Agm in position 29, was evaluated in vivo. All five antagonists, administered at a 27-fold molar excess to rats, suppressed the GH-releasing effect of exogenous GH-RH(1-29)-NH2 by 64-75%. The inhibitory effects lasted for more than 15 min. The most potent analogue, PhAc-[D-Arg2,Phe(4-Cl)6,Abu15,Nle27]hGH-RH(1-28)Agm (MZ-5-156), showed an in vivo potency 7-16 times higher than the early antagonist [Ac-Tyr1,D-Arg2]hGH-RH(1-29)-NH2, which was used as standard. MZ-5-156 was capable of decreasing serum GH levels after intravenous, intraperitoneal, or intramuscular administration. In vitro, in the superfused rat pituitary cell system, MZ-5-156 induced a prolonged inhibition of GH release after continuous long-term administration and showed a potency more than 100 times greater than the standard antagonist. These results show that N-terminal acylation with phenylacetic acid of the sequence [D-Arg2,Phe(4-Cl)6,Nle27]hGH-RH(1-29)-NH2, containing modifications in positions 8, 15, 28, or 29, results in antagonists with high and protracted potency both in vivo and in vitro. In view of high antagonistic activity and prolonged duration of action, some of these antagonists of GH-RH may find clinical application for the treatment of IGF-dependent cancers.