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This paper is devoted to the analysis of the covariant canonical formalism of $F(R)$ gravity in Einstein frame. We also find canonical transformation between covariant canonical formulation of F(R) gravity in Jordan frame and Einstein frames and we also determine corresponding generating function., Comment: 17 pages, reference added

In this short note we perform covariant Hamiltonian analysis of F(R)-gravity., Comment: 12 pages,v2:references added

Polyclonal antibodies to hamster melanoma tyrosinase were raised in rabbits, and series of immunoinhibition experiments with a purified enzyme and specific immunoglobulins were carried out. Tyrosinase activity was determined by a set of radiochemical and spectrophotometric methods utilizing tyrosine, dopa, dopamine, or dihydroxyindole (DHI) as substrates. The quantitative data obtained indicated that the complexing of tyrosinase with its specific antibody inhibited melanogenesis in a specific manner: dopachrome formation from dopa and dopamine conversion to melanin were not affected and all other enzyme activities comprising the DHI oxidation step were inhibited to various degrees. Additionally, tyrosine hydroxylation was also slightly inhibited. The data obtained implied that melanogenesis was restricted at the point of DHI oxidation. From observations on the immunoinhibition of a DHI oxidation at varying dopa-cofactor concentrations, we propose that dopa-cofactor may be bound at separate site than DHI and thus may act as a positive allosteric effector for DHI oxidation by tyrosinase. Study of tyrosinase immunoinhibition by the antibodies against the enzyme thus seems to provide a valuable system for investigating the tyrosinase-mediated melanogenesis.

Two tyrosinase isozymes were purified from pigmented hamster melanoma and injected i.v. into rats. It was shown that while T1 (sialylated) isozyme survived in the circulation, native asialo (T2) isozyme and neuraminidase-desialylated T1 isozyme disappeared from the circulation in a few minutes. Desialylated fetuin had a marked inhibitory effect on the removal of asialo-T1 tyrosinase. These data indicate that the enzyme tyrosinase shares the common pattern of clearance from circulation known for the majority of serum glycoproteins. The electrophoretic pattern of tyrosinase isozymes partially purified from the sera of melanoma-bearing animals were compared with those from the soluble fraction of the tumors. In hamsters, melanoma tissue revealed both T1 and T2 isozymes while serum exhibited T1 and very weak T2, supporting the mechanism of clearance demonstrated in rats. In mice bearing Cloudman S-91 or B-16 melanomas, only T1 isozyme was seen in sera and in tumors.

Little has been known about the excretion of melanogens (melanogenuria) in animals with experimental melanoma. In this report the first information about melanogenuria in hamsters with transplantable melanotic and amelanotic melanoma is given. In hamsters with melanotic melanoma apparently increased concentration and excretion of so called Thormahlen positive melanogens in urine was found in comparison with hamsters with amelanotic melanoma or hamsters without tumours. Similar results were obtained when the excretion of all diazo positive compounds in urine was measured. Thin-layer chromatography of ethyl acetate extracts of hamster urine proved the presence of at least 15 phenolic or indolic acids. Some of them remained unidentified. However, such compounds as p-hydroxyphenylacetic acid, homovanillic acid, vanilmandelic acid or 5-hydroxyindole-acetic acid were identified. Only in the urine of hamsters with melanotic melanoma were we able to detect the isomeric 5-hydroxy-6-methoxyindolyl-2-carboxylic and 6-hydroxy-5-methoxyindolyl-2-carboxylic acids.

Thormahlen positive melanogens (TPM) were determined in the urine of 585 primary and/or metastatic cutaneous melanoma patients, in 105 primary and/or metastatic ocular melanoma patients, in 100 patients suffering from other diseases with the exception of melanoma and in 72 healthly persons. On the basis of our results we can recommend the determination of the sum of TPM as sufficient for routine monitoring of patients in the course of malignant melanoma. The determination of TPM urinary excretion cannot substitute histological and clinical examinations in an early diagnosis of malignant melanoma, but it is very important and useful for a differential diagnosis and prognosis of malignant melanoma. TPM urinary excretion can be followed in melanoma patients also for the indication of further treatment and the evaluation of the response on chemotherapy or immunotherapy.

Two new isomeric metabolites, 5-hydroxy-6-methoxyindole-2-carboxylic (a) and 5-methoxy-6-hydroxyindole-2-carboxylic (b) acids have been identified in melanotic urine: Their constitution was identified by Chromatographic and spectral comparison of the two isomers isolated from urine with the same compounds prepared synthetically.

A simple screening test for estimation of some phenolic and indolic compounds in urine is described. The method is rapid, simple and able to detect all the indolic and phenolic compounds observed, including o-dihydroxy compounds. The method is based on the color reaction with reagent solution composed of sodium tungstate, trichloroacetic acid, hydrochloric acid and sodium nitrite. After alkalinization by sodium hydroxide the optical density is measured at 405 and 490 nm. The latter is specific for o-dihydroxy compounds. This test seems to be useful for estimation of phenolic and indolic compounds in urine of patients with increased production of compounds of this nature, particularly in some tumors.

1. Tyrosinase was purified from melanosomal fraction of hamster melanoma. 2. A radioimmunoassay was developed to quantitate the tyrosinase protein in hamster serum and hamster melanoma tissue using polyclonal anti-tyrosinase antibodies and 125I-labeled enzyme. 3. The serum tyrosinase levels were found to be about 0.24 micrograms and 1.14-4.48 micrograms/ml in normal hamsters and melanoma-bearing hamsters, respectively. 4. Tyrosinase protein in serum correlated significantly with the enzyme activity in hamsters with melanoma (r = 0.733). 5. In the cytosol fraction of hamster melanoma, a level of 2.2 micrograms of tyrosinase/mg protein was determined. 6. The usefulness and possible applications of the tyrosinase radioimmunoassay are discussed.

A simple spectrophotometric method for a rapid determination of tyrosinase (EC 1.14.18.1) is described. The basis of the assay is the incubation of the enzyme with L-dopa in the presence of an optimal concentration of Zn2+ ions and the measurement of the formation of melanochrome, as indicated by the rise in absorbance at 540 nm. Final absorbance change reflects probably two activities of tyrosinase: the oxidation of dopa to dopaquinone and the conversion of 5,6-dihydroxyindole to melanochrome. Using a purified preparation from hamster melanoma, the assay was found to be more sensitive than the commonly used dopachrome assay. Comparison with some other currently available methods for assaying tyrosinase is presented and potential applications of the assay are discussed.

Malignant melanomas are tumours in which one metabolic pathway — such as that used for the formation of a pigment — is conspicuously accentuated in comparison with normal homologous tissues. This accentuation has been investigated by many authors who studied mainly the relation to the final product — melanin — and to the main catalyst of its formation — tyrosinase. However, it is surprising that little attention has been devoted to the actual course of the reaction and to the formation of the intermediates in vivo. Almost all the existing conclusions in this direction were in fact based only on analogies with model reactions in vitro. Nevertheless, already in the past century the socalled melanogens — precursors of melanin — or their metabolites were described in the malignant melanoma in urine 1). There is no doubt that the elucidation of the chemical structure, biogenesis and metabolism of these compounds can contribute substantially to the more detailed knowledge of melanogenesis in vivo and thus to a better knowledge of the biochemistry of malignant melanoma in general.

Germline mutations in two major susceptibility genes BRCA1 and BRCA2 contribute to the majority of inherited breast and ovarian cancers. Besides the germline mutation, tumor progression depends on the loss of a wild-type allele. Allelic losses in the BRCA1 and BRCA2 loci have also been detected in a high proportion of sporadic breast tumors, suggesting the role of these genes in the development of non-inherited breast cancer. Forty unselected breast tumors were analyzed for the loss of heterozygosity (LOH) at BRCA1 and BRCA2 regions and tumors with allelic deletions were screened for the presence of acquired genetic alterations in respective genes. 21.1% of 38 informative tumor samples carried LOH at the BRCA1 locus whereas 33.3% of 39 informative samples showed LOH at the BRCA2 locus. Pathogenic truncating mutations in the BRCA1 gene were found in two tumor samples with allelic losses, whereas no mutations were identified in the BRCA2 gene. Mutations were not detected in non-tumor samples from the same individuals, which indicated that the BRCA1 allele was inactivated by somatic mutations in tumor tissue. The c.1116G>A (1235G>A) nonsense mutation (p.W372X) belongs to the genetic abnormalities detected infrequently in hereditary tumors; the c.3862delG (3981delG) frameshift mutation (p.E1288fsX1306) is a novel gene alteration. The occurrence of inactivating somatic mutations in sporadic breast tumors suggested the role of the BRCA1 gene in tumorigenesis in at least a minor group of patients with non-familial breast cancer. © 2005 Wiley-Liss, Inc.