Iris Ferrari

Some observations on genetic factors in urolithiasis

In an attempt to detect genetic factors linked with urolithiasis, a study based on medical and genetic data and on several biochemical procedures was done on 50 stone formers and on 50 controls. Genetic factors likely to be related to stone forming were found in 4 patients: 2 cases of incomplete renal tubular acidosis, and 2 cases of heterozygous cystinuria. A study of the families of 3 of these individuals revealed 4 additional cases of genetically determined metabolic diseases. Despite the small number of patients for whom genetic factors were determined and the fact that the lithiasis cases with and without family recurrence showed similar behavior with respect to the different biochemical parameters studied, the presence of genetic factors is suggested by the significantly more frequent family history of lithiasis found for stone formers than for the controls. Identifying the cases with family recurrence, in which stone formation occurs earlier and is more frequently recurrent, and the stone-forming patients with genetically determined metabolic disorders, which may benefit from specific measures, will probably contribute to a better prognosis for these patients.

Clastogenic effect of the plant alkaloid ellipticine on bone marrow cells of Wistar rats and on human peripheral blood lymphocytes

Ellipticine (EPC), a natural alkaloid extracted from Aspidosperma williansii (Apocynaceae), is known to have antitumor and cytotoxic activities on various types of tumors. This drug showed a strong clastogenic effect on bone marrow cells of Wistar rats treated in vivo (7.75-31.00 mg/kg body weight). EPC was also tested in vitro using the human peripheral blood lymphocyte system, at concentrations 100 times lower than those used in the in vivo test on rats, since the cytotoxic effect on lymphocytes was very strong. At the 2 highest concentrations used (7.75 X 10(-1) and 1.55 X 10(-1) micrograms/ml culture medium), EPC induced a statistically significant increase in the frequency of chromosome aberrations and sister-chromatid exchanges in lymphocytes. Based on data reported in the literature, we have tried to establish relationships between the clastogenic effect observed and the process of EPC intercalation into DNA and the formation of protein-associated DNA-strand breaks probably promoted by topoisomerase enzymes.

An evaluation of four methods for the detection of heterozygous cystinuria

Heterozygotes for cystinuria (types II and III) may be detected on the basis of slight to moderate elevations in urinary cystine, lysine and sometimes arginine. This seems to be a common genetic trait, and there are indications of an increased risk of urinary stone disease. In order to test the sensitivity and reliability of the procedures normally used for screening and diagnosis of heterozygous cystinuria, we studied 32 heterozygotes previously diagnosed by ion-exchange chromatography of urinary amino acids, and 23 healthy individuals. A random urine sample from each subject was analysed using the cyanide-nitroprusside test, thin-layer amino acid chromatography, colorimetric estimations of cystine and lysine, and ion-exchange amino acid chromatography. Thin-layer chromatography provided the highest sensitivity. Thus the frequency of heterozygotes calculated in previous studies, based on screening by the cyanide-nitroprusside test, may be under-estimated. The colorimetric estimations of cystine and lysine provided low sensitivity as screening tests and, compared with the ion-exchange chromatography, were unreliable diagnostic methods.

Metabolic Factors in Urolithiasis: A Study in Brazil

Clinical and biochemical data were obtained from 50 patients in whom stones form and 20 controls to set up and test a screening procedure for detecting metabolic abnormalities related to the formation of urinary calculi and to provide a preliminary estimate of the frequency of these disorders in our area. A comparison between patients in whom stones form and controls in terms of the quantitative biochemical parameters evaluated (serum calcium, uric acid and inorganic phosphate, and urine calcium, uric acid, inorganic phosphate, oxalic acid, xanthine and alpha-amino-nitrogen) showed a significant difference only with respect to excretion of urinary oxalate by adults, which was higher in patients in whom stones form. Metabolic disorders were detected in 15 adult patients with stones. Of these patients 9 had isolated hyperoxaluria, 3 had incomplete renal tubular acidosis, 1 had idiopathic hypercalciuria, 1 had heterozygous cystinuria and 1 had idiopathic hypercalciuria associated with heterozygous cystinuria. These results suggest a high frequency of metabolic abnormalities in patients in whom stones form in our area, so that the wider use of the screening used here may benefit a large number of patients with preventive and therapeutic measures.

Sex Determination of the « Pseudo-XO/XX » Type in the Brazilian Lizard Polychrus Sp. (Sauria, Iguanidae)

SUMMARYThe karyotype of the Brazilian lizard Polychrus sp showed 2n=20 chromosomes for the female and 2n=19 chromosomes for the male. The meiotic cells of the male in diakinesis and metaphase I showed 8 bivalents and 1 trivalent. In metaphase II there were cells with n=9 chromosomes, and cells with n = 10 chromosomes. The sex determining mechanism was interpreted as belonging to the « pseudo XO/XX » type, which differs from the X1X2Y/X1X1X2X2 type because the Y is morphologically indistinguishable from the X2 chromosome. This is the second occurrence of this case to be described in the vertebrates.

Frequency of cystinuria among stone-forming patients in region of Brazil☆

Occasional urine samples from 200 stone-forming individuals were screened by the successive application of the cyanide-nitroprusside test, qualitative-semiquantitative thin-layer amino acid chromatography, and quantitative ion-exchange amino acid analysis to determine the frequency of cystinuria in this region of Brazil. Only 1 homozygous cystinuria patient was detected, a lower frequency than 1 to 6 per cent reported in other countries. The patients family showed a I/I genotype. Since 6 heterozygotes for cystinuria +/II or +/III were also detected, the relative rarity of homozygotes in this sample supports the view of the relatively greater contribution of etiologic factors other than gene frequency to stone formation. The importance of diagnosis based on quantitative amino acid analysis is emphasized because of the different therapeutic and prognostic implications of the homozygote and heterozygote forms of the disease.

ESTUDO CARIOTÍPICO EM DUAS ESPÉCIES DE CUCULIFORMES AMERICANOS (Aves) ()

Two species of birds of the Cuculidae Family, Playa cayana (Phaenicophaeinae) and Crotophaga major (Crotophaginae), captured in Manaus (AM, Brazil) region have been cytogenetically studied. The chromosomes were preparared for 4 hours in culture using bone narrow cells. The karyotypic analyses were done by convencional methods from which numerical, morphological and metrical data of the chromosomes were drawn. The mean size of the macrochromosomes, the Relative Lengths (PR) and Arm Ratlos (B) were calculated on the basis of the measurements obtained. A system on decreasing order of size was used to arrange the chromosomes, designating each chromosome individually. The macrochromosomes were morphologically classified according to Levan et al. (1964). All chromosomes that had PR equal or bigger than 4% were considered as macrochromosomes. P. cayana has 2n complement of 76 chromosomes, from which 22 are considered as macrochromosomes. The Z chromosome is submetacentric and the second of the karyotype, however the W is subtelocentric and the eleventh in size. C. major has 64 chromosomes, from which 22 are macro-chromosomes. The Z chromosome is metacentric and the fourth of the karyotype, but the W chromosome is submetacentric and the sixth in size.