Outcome impact of PIK3CA mutations in HER2-positive breast cancer patients treated with trastuzumab.

BACKGROUND: Phosphatidylinositol 3-kinase (PI3K) pathway activation has been suggested to negatively influence response to anti-HER2 therapy in breast cancer patients. The present study focused on mutations of the PIK3CA gene, encoding one of the two PI3K subunits. METHODS: PIK3CA mutations were assessed by direct sequencing in 80 HER2-positive patients treated with 1 year of trastuzumab. All patients preoperatively received four cycles of anthracycline-based chemotherapy, followed by four cycles of docetaxel and 1 year of trastuzumab, starting either before surgery with the first cycle of docetaxel and continuing after surgery (neoadjuvant trastuzumab arm, n=43), or only after surgery (adjuvant trastuzumab arm, n=37). RESULTS: PIK3CA mutations were found in 17 tumours (21.3%). Better disease-free survival (DFS) was observed in patients with PIK3CA wild-type compared with mutated tumours (P=0.0063). By combining PIK3CA status and treatment arms, four separate prognostic groups with significantly different DFS (P=0.0013) were identified. CONCLUSION: These results confirm that the outcome of HER2-positive patients treated with trastuzumab is significantly worse in patients with PIK3CA-mutated compared with wild-type tumours.

CDKA and CDKB kinases from Chlamydomonas reinhardtii are able to complement cdc28 temperature-sensitive mutants of Saccharomyces cerevisiae.

Cyclin-dependent kinases (CDK) play a key role in coordinating cell division in all eukaryotes. We investigated the capability of cyclin-dependent kinases CDKA and CDKB from the green alga Chlamydomonas reinhardtii to complement a Saccharomyces cerevisiae cdc28 temperature-sensitive mutant. The full-length coding regions of algal CDKA and CDKB cDNA were amplified by RT-PCR and cloned into the yeast expression vector pYES-DEST52, yielding pYD52-CDKA and pYD52-CDKB. The S. cerevisiae cdc28-1N strain transformed with these constructs exhibited growth at 36 degrees C in inducing (galactose) medium, but not in repressing (glucose) medium. Microscopic observation showed that the complemented cells had the irregular cylindrical shape typical for G2 phase-arrested cells when grown on glucose at 36 degrees C, but appeared as normal budded cells when grown on galactose at 36 degrees C. Sequence analysis and complementation tests proved that both CDKA and CDKB are functional CDC28/cdc2 homologs in C. reinhardtii. The complementation of the mitotic phenotype of the S. cerevisiae cdc28-1N mutant suggests a mitotic role for both of the kinases.

Determination of isoprene in human expired breath using solid-phase microextraction and gas chromatography-mass spectrometry.

An analytical method for determination of isoprene in expired breath as a marker of body cholesterol synthesis was developed with a special emphasis on breath sampling. Patients were breathing controlled air using respiratory masks for 2 min (washout period) and then their expired breath was collected in 8-1 Tedlar bags. The bags were heated to 40 degrees C and the solid-phase microextraction fiber Carboxen-polydimethylsiloxane 75 microm was inserted through the septum. Extraction time was 10 min. Analytes were desorbed in the GC injector for 2 min at 270 degrees C. Analyses were performed on a Q-PLOT column and fragment ions 68, 67 and 53 were quantified. The concentration range was 1-40 nmol/l, limit of detection was 0.25 nmol/l, the calibration curve was linear. Precision, expressed as RSD, was 5.5-12.5%. These tests are non-invasive, feasible and relatively inexpensive.

Nephrotoxic effects of unleaded petrol in female rats.

Female Wistar rats were exposed to 4 g m-3 unleaded petrol for 8 h a day, 5 days a week for 60 days. Urinary beta 2-microglobulin (beta 2-m), lactate dehydrogenase (LDH) and lysozyme were used as markers of tubular dysfunction. Urinary excretion of albumin and the glomerular filtration rate (GFR) were used as indicators of glomerular impairment. There were no statistically significant changes in the GFR or urinary albumin concentrations in the exposed group. Petrol exposure induced an increase of beta 2-m, total proteins, lysozyme and LDH excretion, but only beta 2-m was increased significantly. Our results show that subchronic exposure to high levels of unleaded petrol induced only a mild proximal tubular dysfunction in female rats.

Distribution of nickel in body fluids and organs of rats chronically exposed to nickel sulphate.

1. Male and female rats were given 100 mg Ni L-1 (as nickel sulphate) in drinking water for 6 months. 2. The feeding of nickel was associated with an increased concentration of nickel in body fluids and organs. The highest concentrations of nickel were found in the liver of both male and female rats. In male rats nickel levels decreased in the order: liver > kidney = whole blood = serum > testes > urine. In female rats the decreasing order was similar: liver > kidney = whole blood = serum = plasma > urine > ovaries. 3. No significant differences were found between nickel concentrations in organs (except ovaries), blood and urine of rats exposed for 3 months and those exposed for 6 months indicating the reaching of a steady state of nickel in the rat during long-term exposure. 4. The urinary excretion of the orally administered nickel was only 2% of absorbed dose (supposing 1% Ni absorption).

Renal alterations in female rats following subchronic lead exposure.

Female Wistar rats were given 1% or 0.1% lead acetate in drinking water for 2 or 4 months, respectively. Urinary beta 2-microglobulin, N-acetyl-beta-D-glucosaminidase, lactate dehydrogenase and lysozyme were used as markers of tubular dysfunction. Excretion of albumin and glomerular filtration rate were used as indicators of glomerular impairment. Kidney and body weights and morphological changes in the kidney were also studied. Exposure to 1% lead acetate induced a mean blood lead level of 1730 micrograms l-1 and caused only an increase of beta 2-microglobulin excretion and relative kidney weight. Light microscopy of kidney revealed morphological changes mainly in the epithelial cells of the proximal tubules. The role of acetate or reduced water intake on kidney function was excluded because 1% sodium acetate or the restriction of water intake to the volume consumed by the rats of the lead-exposed group was ineffective. Exposure to 0.1% lead acetate induced a blood lead level of 376 micrograms l-1, corresponding to the current level in industry workers, without any sign of nephrotoxicity. Comparison of this study with the results of a previous study on male rats indicates no sex difference in the nephrotoxicity of lead.

Effect of prenatal and postnatal exposure to lead on kidney function in male and female rats.

The effect of 5 months' exposure to 0.5% lead acetate in drinking water on the kidney function of developing rats was studied. In both sexes, lead exposure produced a significant elevation of the kidney weight and after 3 months' treatment both male and female rats showed signs of tubular impairment. In male rats increased beta 2-microglobulin and lactate dehydrogenase excretion was observed. Lysozyme was increased after 5 months of exposure. No changes were observed in total proteins and albumin excretion. Female rats showed a significantly increased excretion of beta 2-microglobulin from 3 months onwards, while lactate dehydrogenase increased only at the end of 3 months and total proteins after 5 months of exposure. No changes were observed in lysozyme and albumin excretion. Thus, the results suggest that lead exposure produces changes in the renal tubular function of developing rat. There is no sex difference in the nephrotoxicity of lead. Comparison with our previous studies suggests that exposure to lead starting at weaning is more renotoxic than exposure starting 2 months later. However, prenatal exposure might also have been a contributory factor.

Chronic nephrotoxicity of soluble nickel in rats.

1. Male and female Wistar rats were given 100 mg L-1 of nickel (as nickel sulfate) in drinking water for 6 months. Lactate dehydrogenase, total proteins, N-acetyl-beta-D-glucosaminidase (NAG), albumin and beta 2-microglobulin were measured in 24 h urine after 3 and 6 months of exposure. Body and kidney weights were also recorded. 2. After 6 months, urinary excretion of albumin in control and exposed rats was 354 and 1319 micrograms 24 h-1 for female rats (P < 0.05) and 989 and 2065 micrograms 24 h-1 for male rats (P = non significant). Kidney weights were significantly increased in the exposed groups. No significant changes were observed in other parameters. 3. The results suggest that low-level oral exposure to soluble nickel either induces changes of glomerular permeability in female and possibly in male rats, or enhances the normal age-related glomerular nephritis lesions of ageing rats. The intake was probably not high enough to induce significant tubular changes. The female rat seems to be more sensitive to the nephrotoxic effect of nickel than the male rat.

Biochemical renal changes in workers exposed to soluble nickel compounds.

1. Biochemical markers of kidney damage were examined in 14 male and 12 female workers highly exposed to soluble nickel compounds in a chemical plant. The results were compared to those obtained in 12 male and 12 female matched controls. 2. The concentration of nickel in urine of male and female workers averaged 5.0 and 10.3 micrograms g-1 creatinine, respectively. The mean duration of exposure in male and female workers was 25 and 15 years. 3. No difference was found in the mean urinary excretion of lactate dehydrogenase, albumin and transferrin in both sexes, total proteins, beta 2-microglobulin (beta 2-m) and retinol-binding protein (RBP) in males and lysozyme in females. Lysozyme and N-acetyl-beta-D-glucosaminidase (NAG) were increased in male and total proteins, beta 2-m, NAG and RBP in female exposed workers. Significant correlations between urinary concentrations of nickel on one side and that of beta 2-m in women (r = 0.462, P = 0.022) and men (r = 0.41, P = 0.018) and of NAG in men (r = 0.405, P = 0.019) on the other side were found in exposed subjects. 4. Results indicate adverse effects of soluble nickel compounds on the kidney tubular function. In agreement with literature data it seems that those effects occur only at high exposure levels.

Kidney function in male and female rats chronically exposed to potassium dichromate.

Male and female Wistar rats were given 25 mg l-1 chromium (as potassium dichromate) in drinking water for 6 months. Lactate dehydrogenase, lysozyme, total proteins, N-acetyl-beta-D-glucosaminidase, albumin and beta 2-microglobulin (beta 2-m) were measured in 24-h urine after 3 and 6 months of exposure. Body and kidney weight and chromium excretion were also examined. Except for the chromium excretion, no statistically significant changes were observed in the exposed male rats. In female rats there were significant increases in the urinary excretion of albumin after 3 and 6 months of exposure and the urinary excretion of beta 2-m after 3 months of exposure.

[Lactic acidosis as a complication of treatment with biguanides]. / Laktátová acidóza jako komplikace lécby biguanidy.

In the course of two and a half years we treated six diabetic women on account of lactate acidosis during concurrent biguanide administration. The patients were given an average dose of 290 mg Buformin/24 hours. Their mean age was 71 years. Three patients died, i.e. the mortality was 50%. All patients reported nausea, vomiting and abdominal pain. Two suffered from diarrhoea. Two patients suffered from renal failure and one from cardiac weakness. One patient was in coma. The mean lactate concentration was 14.7 mmol/l, pH on admission was 6.84. The patients were given on average 550 mmol bicarbonate. In two instances bicarbonate dialysis was used. The authors discuss the pathophysiology, clinical aspects and importance for treatment and prevention of lactate acidosis during biguanide treatment.