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Distortions of the sqrt[3]x sqrt[3] Sn/Ge(111) and Sn/Si(111) surfaces are shown to reflect a disproportionation of an integer pseudocharge, Q, related to the surface band occupancy. A novel understanding of the (3 x 3)-1U ("1 up, 2 down") and 2U ("2 up, 1 down") distortions of Sn/Ge(111) is obtained by a theoretical study of the phase diagram under strain. Positive strain keeps the unstrained value Q=3 but removes distortions. Negative strain attracts pseudocharge from the valence band causing first a (3 x 3)-2U distortion (Q=4) on both Sn/Ge and Sn/Si, and eventually a (sqrt[3] x sqrt[3])-3U ("all up") state with Q=6. The possibility of a fluctuating phase in unstrained Sn/Si(111) is discussed.

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DNA topoisomerases, nuclear enzymes that regulate DNA topology, are recognized as the primary targets of effective anti-tumor drugs. These enzymes may also have a role in the repair of DNA damage induced by alkylating agents and platinum compounds; therefore, their expression may be a determinant of tumor response to chemotherapy. Our study was undertaken in an attempt to establish a correlation between the enzyme expression and response of ovarian cancer to cisplatin-based chemotherapy. The expression of topoisomerase I, II alpha and II beta genes was assessed by RNase protection assay in tumor specimens obtained from 37 untreated patients with advanced epithelial ovarian cancer at initial surgery and from 13 pre-treated patients at subsequent laparotomy. The expression levels were compared with those found in 5 specimens from benign ovarian tissue and 5 specimens from normal ovarian tissue. The expression levels in untreated patients were used to establish a correlation with response to high-dose cisplatin therapy. A significant intertumor variability of mRNA expression was noted for all the genes examined. However, a comparison of median values indicated a remarkable increase of expression in malignant tumors over benign or normal tissues only for topoisomerase II alpha. This change is not related to alterations or amplification of topoisomerase II alpha gene. Interestingly, a correlation was found between tumor response to chemotherapy and the expression level of the isoform alpha (but not of topoisomerase II beta and topoisomerase I). The observed correlation suggests a contribution of the enzyme in determining tumor sensitivity. Alternatively, increased expression levels of the alpha isoenzyme gene in responsive tumors might reflect higher fractions of proliferating tumor cells that may be more drug-sensitive than resting cells.

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Since its identification in seminal fluid in 1971, much new information has been obtained about the biology and expression of prostate-specific antigen (PSA). PSA is a glycoprotein composed of 93% amino acids and 7% carbohydrates, with a molecular weight of about 30,000 Da. Functionally and structurally PSA is a kallikrein-like serine protease, and its physiologic role is degradation of the major proteins of seminal coagulum (semenogelin I and II, fibronectin), which leads to semen liquefaction. The PSA gene is located on the 13q region of chromosome 19, and it has a high degree of homology (more than 80%) with genes of the human glandular kallikrein (hKGK1). PSA production and expression are preferentially but not exclusively associated to the normal, benign hyperplastic and cancerous tissues of the prostate. In fact, it has been demonstrated that PSA is also present in accessory male sex glands and breast cancer. It was recently reported that PSA was also present in milk of lactating women. Many factors may influence PSA synthesis and production, and among them the most important are androgen, retinoic acid and growth factor stimulation. Significant advances have been recently made as regards the molecular isoforms of PSA. In the seminal fluid PSA seems partially bound to a serpine (protein C inhibitor), whereas in serum it is predominantly associated to alpha-1-antichymotrypsin and in a small quantity to alpha-2-macroglobulin. These new findings will have implications for the clinical application of PSA as a tumor marker for prostate cancer.

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Statural growth and its relation to growth potential, renal function, blood urea nitrogen (BUN), mineral metabolism hormones and dietary intake were studied in 17 prepubertal children (aged 1.6-9.3 years) on conservative treatment for chronic renal failure due to tubulo-interstitial nephropathy. Statural growth (height SDS) was related to the degree of renal failure, was more retarded than ossification, and was independent of the chronological age of the patients. We observed that the lower the glomerular filtration rate (GFR), the lower was the growth potential (increased bone age/statural age ratio). Growth velocity may be normal regardless of statural and bone maturation delay and the degree of renal insufficiency. Impaired growth rate correlated with parathyroid hormone levels, caloric intake and increased blood urea nitrogen during the year of observation. These data show that comprehensive monitoring and suitable treatment must be performed in order to prevent growth retardation at any GFR level.

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Haemophilia is a bleeding disorder characterized by decreased activity of the circulating antihemophilic factor, with different degrees of severity. The prognosis of the disease for an useful normal life is good, providing an adeguate follow-up. We think that the auxological determinants of growth and nutritional status must enter as points of a multicentre follow-up sheet of haemophilia in the pediatric age. We have tried such an approach in 13 patients; preliminary results have shown that all patients are growing well with some degrees of discrete malnutrition (arm circumference less than -1.6 SD). From costitutional point of view, haemophilic boys show a discrete "lean" body pattern (W/H2 less than or equal to O SD(with their trunk longer than legs. Data from other studies are wellcome for confirming our first impressions.

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Chronic hepatitis in children seems to have a better prognosis than in adults, with a discrete trend to spontaneous remission. Actually biopsy and liver enzymes are mandatory for a correct follow up of the disease, while few authors are interested in the assessment of growth and nutritional status. We think that an auxological approach is one of the main points in every chronic disease of the pediatric age, chiefly when some anabolic step might be affected. Our first result in a cross sectional study of growth and nutritional status in a selected group of untreated HBsAg+ chronic hepatitis children are as follows. According to enzyme values in the range of 16-171 UI/1 SGOT all patients are growing very well with a good-discrete nutritional status. Though anthropometric proteic nutritional status (muscle circumference) was in the range of normal distribution, we were able to show a moderate correlation between SGOT and muscle circumference (r = -0,50). Our impression is that some patients with a worse hepatic damage can be exposed at risk of proteic malnutrition which is a negative element in the prognosis of every chronic disease. Anthropometric auxology can detect degrees of proteic malnutrition, and can follow its development. So we recommend routine auxological assessment in all pediatric patients with chronic hepatitis.

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