Maria Bistocchi

[3H]Ro 15-1788 binding sites to brain membrane of the saltwater Mugil cephalus

The equilibrium binding parameters of the benzodiazepine antagonist [3H]Ro 15-1788 (8-fluoro-3-carboethoxy-5,6-dihydro-5-methyl-6-oxo-4H-imidazol-[1,5-a]-1,4 benzodiazepine) were evaluated in brain membranes of the saltwater teleost fish, Mugil cephalus. To test receptor subtype specificity, displacement studies were carried out by competitive binding of [3H]Ro 15-1788 against six benzodiazepine receptor ligands, flunitrazepam [5-(2-fluoro-phenyl)-1,3-dihydro-1-methyl-7-nitro-2H-1,4-benzodiazepin-2-one], alpidem [N,N-dipropyl-6-chloro-2-(4-chlorophenyl)imidazo[1,2-a]pyridine-3-acetamide], zolpidem [N,N-6 trimethyl-2-(4-methyl-phenyl)imidazo[1,2-a]pyridine-3-acetamide hemitartrate], and beta-CCM (methyl beta-carboline-3-carboxylate). Saturation studies showed that [3H]Ro 15-1788 bound saturatably, reversibly and with a high affinity to a single class of binding sites (Kd value of 1.18-1.5 nM and Bmax values of 124-1671 fmol/mg of protein, depending on brain regions). The highest concentration of benzodiazepine recognition sites labeled with [3H]Ro 15-1788 was present in the optic lobe and the olfactory bulb and the lowest concentration was found in the medulla oblongata, cerebellum and spinal cord. The rank order of displacement efficacy of unlabelled ligands observed suggested that central-type benzodiazepine receptors are present in one class of binding sites (Type I-like) in brain membranes of Mugil cephalus. Moreover, the uptake of 36Cl- into M. cephalus brain membrane vesicles was only marginally stimulated by concentrations of GABA that significantly enhanced the 36Cl- uptake into mammalian brain membrane vesicles. The results may indicate a different functional activity of the GABA-coupled chloride ionophore in the fish brain as compared with the mammalian brain.

Early Pathologic Changes in Experimental and Human Breast Cancer: Facts and Commentsa

All morphologic structures or pathophysiologic changes in the mammary glandular tree develop as a result of the hormonal stimuli that the gland receives. In this respect the breast represents the most typical example in the body of a dynamic structure. In fact, this end organ of the endocrine system converts the hormonal stimuli into morphologic structures, thus almost continuously changing its size, boundaries, and gross and histologic features. This paper deals with the earliest pathologic changes that may be observed in experimental and in human breast cancer, with particular emphasis on the biologic background and progression of these changes. However, only a few points and problems in the biology and pathology of breast carcinogenesis will be raised and commented upon in order to stimulate fruitful speculation and discussion.

Quantitative determination of mammary tumor virus in individual samples of mouse milk.

The possibility to determine quantitatively the intact mammary tumor virus (MTV) in milk of mice carrying milk-transmitted MTV has been assayed by a method that allows direct comparison between individual milk samples. The method is based on (a) the measure of light scattering of partially purified MTV preparations, (b) the use of milk from genetically identical MTV free mice as blank and (c) the quantitative reference to the total protein content of whole milk. The sensitivity, specificity and reproducibility of the procedure, as well as the requirement of appropriate quantitative references, are illustrated and discussed. BALB/c (MTV free), BALB/cfC3H, and BALB/cfRIII mice have been used.

p53 Mutations and Histologie Type of Invasive Breast Carcinoma

A polymerase chain reaction-single strand conformation polymorphism assay was used to assess p53 mutations in 148 invasive breast carcinomas, selected on the basis of their histotype. They comprised 56 lobular, 47 ductal, 19 mucinous, 18 medullary, and 8 papillary carcinomas. The distribution of p53 mutations was significantly different (P = 0.006) in the histotypes examined: mutations were frequent in medullary (39%) and ductal (26%), less common in lobular (12%), and absent in mucinous and papillary carcinomas. The frequency of mutations in the exon 5 of the p53 gene was significantly higher in medullary carcinomas than in the other histotypes: 5 (63%) of the mutations found in exon 5 were observed in medullary carcinomas (P = 0.012). One hundred twenty-two tumors from the total were also examined by immunohistochemistry for p53 overexpression using antibody PAb 1801. A specific immunostaining in neoplastic cells was present in 12 tumors. A strong correlation (P < 0.001) was observed between p53 mutations and nuclear accumulation of the p53 protein: 10 tumors were scored positive for both p53 mutation and overexpression. However, in 9 cases having a mutated p53 gene we failed to find a positive immunoreaction. A significant association (P = 0.01) was present between mutations in the p53 gene and high proliferative activity of the tumors determined by immunohistochemistry with monoclonal antibody Ki-67. Moreover, a significantly higher expression of the Ki-67 antigen was found in medullary carcinomas compared to the other histotypes. Our findings indicate that in invasive breast carcinomas structural abnormalities of the p53 gene are mainly seen in medullary and ductal tumors and that the other histological types, especially those associated with a high level of differentiation and favorable prognosis, show a very low incidence of p53 mutations.

Quantitative comparison of milk-released C3H and RIII mammary tumor viruses in infected BALB/c hosts.

The C3H and RIII mammary tumor viruses (MTV) carried by BALB/cfC3H and BALB/cfRIII breeding females have been quantified and compared in milk samples, after partial purification with a sucrose density gradient. The samples were collected at identical times during the first 3 lactation periods from individual mice (6 per strain), standardized for age at delivery and size of litter. Milk samples from 6 MTV negative BALB/c controls have also been analyzed. Data for comparison are expressed in optical density units (ODU) and refer to the protein content of the whole milk using MTV-negative BALB/c milk as blank. The results have shown 1) an increase of MTV released through milk in each MTV-carrying female from the first (average ODU, 0.542) to the second (1.351) and third (2.105) lactation, 2) individual variations, and 3) a significant difference in release between C3H and RIIl MTV, the latter being more than double (average ODU, 1.801) in respect to the former (0.847). The apparent discrepancy between these results and the bioactivity in BALB/c mice of C3H and RIII MTV, significantly lower for the latter, is discussed.

Autoradiographic distribution of peripheral benzodiazepine receptors in the retina of the albino rabbit, Lepus cunicula

The distribution of peripheral benzodiazepine receptors (PBRs) in the retina of the albino rabbit, Lepus cunicula, was studied by autoradiography using [3H]-PK11195, a isoquinoline carboxamide, as a tracer. Autoradiograms obtained by directly placing the slides containing the retina sections on tritium-sensitive film provide evidence for the presence of PBRs in rabbit retina. Furthermore, the dark field examination of photomicrographs taken from autoradiograms showed two dense horizontal bands corresponding to the outer and inner photoreceptor segments, and to the inner plexiform layer. The retinal regions where [3H]-PK11195 binding was more dense are rich in mitochondria, suggesting that as in other neuronal tissues, retinal PBRs are involved in the mitochondrial activity.