A molecular model for the control of cell size has been developed. It is based on two molecules, one (I) acts as an inhibitor of the entrance into S phase, and it is synthetised just after cell separation in a fixed amount per nucleus. The other (A) is an activator of the S phase, and it is synthetised at a ratio proportional to the overall protein accumulation. The activator reacts stoichiometrically with (I), and after all the (I) molecules have been titrated, (A) begins to accumulate. When it reaches a threshold value, it triggers the onset of DNA replication. This model was tested by simulation and when applied to the case of unequal division explains a number of features of an exponentially growing yeast cell population: (a) the lengths of TP (cycle time of parent cells) and TD (cycle time of daughter cells) verify the condition exp(- KTP ) + exp(- KTD ) = 1; (b) the changes of the average cell size of populations at different growth rates; (c) the frequency of parents and daughters at various growth rates; (d) the increase of cell size at bud initiation for cells of increasing genealogical age; (e) the existence of a TP - TB period (difference between the cycle time of parents and the length of budded phase) that depends linearly upon the doubling time of the population.

Cell Cycle↗

PubMedDate not supplied

The aromatase inhibitor letrozole in advanced breast cancer: effects on serum insulin-like growth factor (IGF)-I and IGF-binding protein-3 levels.

Serum insulin-like growth factor (IGF)-I and IGF-binding protein-3 levels were measured in two groups of postmenopausal women with advanced breast cancer, who received the aromatase inhibitor letrozole 0.5 or 2.5 mg p.o. once daily. Blood samples were obtained from 15 patients in each dose group at baseline, and one and three months after starting therapy. Circulating IGF-I and IGFBP-3 concentrations were determined by means of radioimmunoassay. In both dosage groups a statistically significant increase in the IGF-I levels was observed during three months of letrozole treatment (P=0.003). In addition, the multiple testing procedure yielded in the whole patient population a significant result in the comparison between mean IGF-I values after three months of therapy and those observed at baseline (P=0.004), the estimated average increase being of 24%. No significant result was obtained in the analysis for the dose effect (P=0.077) and for the time x dose interaction (P=0.208). Circulating IGFBP-3 levels did not appear to be affected by letrozole treatment in either of the dose groups. This is the first report concerning the short-term effects of letrozole on components of the IGF system in breast cancer patients; further investigations are warranted in order to confirm these preliminary data.

Aged↗

PubMedDate not supplied

Perioperative total parenteral nutrition in malnourished, gastrointestinal cancer patients: a randomized, clinical trial.

BACKGROUND: Clinical trials investigating the potential benefits of perioperative total parenteral nutrition (TPN) for reducing the risk of surgery in malnourished cancer patients have yielded controversial results. METHODS: Ninety elective surgical patients with gastric or colorectal tumors and weight loss of 10% or more of usual body weight were randomly assigned to 10 days of preoperative and 9 days of postoperative nutrition vs a simple control group. The daily per kilogram body weight TPN regimen included 34.6 +/- 6.3 kcal nonprotein and 0.25 +/- 0.04 g nitrogen per kilogram in a volume of 42.6 +/- 7.3 mL of fluid. The glucose-to-fat calorie ratio was 70:30. Control patients did not receive preoperative nutrition but received 940 kcal nonprotein plus 85 g amino acids postoperatively. RESULTS: Complications occurred in 37% of the patients receiving TPN vs 57% of the control patients (p = .03). Noninfectious complications mainly accounted for this difference, which was 12% vs 34%, respectively (p = .02). Mortality occurred in only 5 of the control group patients (p = .05). The total length of hospitalization for TPN patients was longer than for control (p = .00), whereas the length of postoperative stay in the two groups did not differ significantly. CONCLUSIONS: This study shows that 10 days of preoperative TPN that is continued postoperatively is able to reduce the complication rate by approximately one third and to prevent mortality in severely malnourished patients with gastrointestinal cancer.

Aged↗

PubMedDate not supplied

Double-contrast barium enema and computerised tomography in the pre-operative evaluation of rectal carcinoma: are they still useful diagnostic procedures?

PURPOSE: In modern management of rectal carcinoma, the preoperative evaluation of disease parameters is important for selection of therapeutic options. Such parameters are currently defined through endorectal ultrasonography or endoscopic ultrasonography. A retrospective analysis of the parameters obtained with double-contrast barium enema (DCBE) and endorectal balloon computed tomography (CT) was conducted to verify the diagnostic reliability of the radiological techniques and to establish whether there is still an indication for their use. METHODS: 53 consecutive patients with adenocarcinoma of the distal half of the rectal ampulla underwent double contrast barium enema examination and CT of the pelvis with endorectal balloon. On the basis of the DCBE and CT assessment we evaluated: 1) the distance between the cranial extremity of the anal canal and the distal margin of the neoplasm; 2) the radial diffusion of the tumor; 3) the metastatic involvement of the perirectal and inferior mesenteric lymph nodes. RESULTS: 1) CT and DBCE measurements of the distal margin tended to coincide, but both tended to overestimate the measurement when compared to the pathologic examination; 2) in the identification of neoplastic infiltration of perirectal fat (T3) CT had 100% sensitivity, 78.7% specificity and 86.8% accuracy; 3) the CT sensitivity for detecting lymph node metastasis was 52.6%, specificity 85.3% and accuracy 73.6%. CONCLUSIONS: The diagnostic information provided by the radiological examinations is comparable to that of clinical and instrumental methods currently employed for staging of rectal carcinoma, although the latter are preferred because they are more readily accessible and less costly. DCBE and CT can therefore be usefully employed for staging of cancer of the rectum in those cases in which there are limitations of the current standard methods.

Adenocarcinoma↗

PubMedDate not supplied

Chemoprevention of breast cancer with fenretinide (4-HPR): study of long-term visual and ophthalmologic tolerability.

BACKGROUND: Fenretinide (4-HPR) is a synthetic retinoid being clinically tested in the chemoprevention of different tumors and precancerous lesions. Though safer than many other retinoids in experimental models, in humans 4-HPR may induce adverse effects that mainly affect the eye and visual function. Such effects are thought to be caused by the reduction of plasma retinol levels, which occurs after administration of the retinoid. METHODS: A series of 826 women treated with 4-HPR was studied to quantify the incidence and temporal pattern of occurrence of visual (dark adaptation) and ophthalmologic complaints (ocular dryness, lacrimation, conjunctivitis or photophobia) and to investigate the possible association between their occurrence and plasma retinol levels. RESULTS: The cumulative incidence of visual complaints reached nearly 20% at 5 years. The occurrence of these symptoms was more frequent at the start of treatment. The probability of developing visual complaints was significantly higher in patients with lower plasma retinol concentrations following 4-HPR treatment. The cumulative incidence of ophthalmologic complaints was 8% at 5 years. The occurrence of these complaints was evenly distributed during treatment. Ophthalmologic complaints were not associated with a greater degree of reduction of plasma retinol concentrations, but rather with the patient's age, since symptomatic patients were generally older than asymptomatic patients. CONCLUSIONS: Visual and ophthalmologic complaints are common during 4-HPR treatment; their estimated 5-year cumulative incidence is close to 20% and 8%, respectively. However, the pattern of occurrence over time and the underlying mechanisms of these two types of complaints seem different.

Adult↗

PubMedDate not supplied

Chemoprevention trial of contralateral breast cancer with fenretinide. Rationale, design, methodology, organization, data management, statistics and accrual.

The Fenretinide (4-HPR) Breast Cancer Study is a randomized multicenter clinical trial originally designed and conducted by the investigators of the Istituto Nazionale Tumori of Milan. The study is sponsored by the National Cancer Institute of Bethesda and by the Italian National Research Council. The trial was designed to evaluate the effectiveness of the synthetic retinoid 4-HPR, at a dose of 200 mg per os every day for 5 years, in reducing the incidence of contralateral breast cancer in a population of patients previously operated on for breast cancer. Between 1987 and 1993, the Istituto Nazionale Tumori of Milan and 9 other collaborating Centers enrolled 2,972 women between the ages of 30 and 70 years who had been previously operated on for T1-T2 N- M0 breast cancer. This paper describes the rationale, design, methodology, organization, data management, statistics and accrual of the participating population.

Adult↗

PubMedDate not supplied

Impact of distal clearance margin on oncologic outcome after restorative resection of the rectum.

There is considerable controversy about the distal clearance margin that needs to be maintained beyond the extent of a rectal tumor in order to reduce the risk of local recurrence. We investigated the rate of local recurrence, distant metastases and survival in 87 patients who had undergone radical restorative resection of the rectum for cancer and had been followed up for a median period of over 6 years, and we analyzed the statistical relation (log-rank test for trend) with the length of the distal margin. The distal margin length was divided into three categories: 1 cm, 2 cm, and > or = 3 cm. No significant correlation was found between the length of the distal clearance margin and the oncologic outcome. Taken together, our data suggest that if the resection line distally falls on healthy tissue, there is no need to resect additional rectum in order to achieve a better outcome.

Adult↗

PubMedDate not supplied

Accrual issues for chemoprevention trials: the example of the 4-HPR study for the prevention of contralateral breast cancer.

This paper describes the accrual of the controlled clinical trial with fenretinide for the prevention of contralateral breast cancer. Accrual screened 4,030 potentially eligible patients of whom 1,815 were randomized. Two strategies of recruitment were used, i.e. retrospective and prospective. In the retrospective accrual, the medical staff reviewed the records of breast cancer patients who had received curative surgery to select those who fulfilled the eligibility criteria of the study. For the prospective recruitment operated, patients were contacted after the beginning of the trial. The study started in March 1987 and accrual closed on July 31, 1993. The planned accrual period was extended by 19 months. The yearly accrual tended to decrease with time. This was mainly due to the end of the retrospective recruitment and to the introduction of adjuvant chemotherapy, a reason for exclusion from the trial, also for patients with negative axillary nodes. The known accrual difficulties of chemoprevention studies proved also to be true for the high-risk population of this trial.

Antineoplastic Agents↗

PubMedDate not supplied

Evaluation of reactive oxygen metabolites in frozen serum samples. Effect of storage and repeated thawing.

Measuring the free radical activity in serum samples from prospective studies is the best way to investigate the association between oxidative stress and human diseases. Prospective studies require the analysis of serum samples that have often been stored for a long time. Our study was designed to determine the effect of storage at -30 degrees C and -80 degrees C for two years on free radical activity. We analyzed the free radical activity by measuring circulating hydroperoxides in a pool of sera at baseline and after one day, one week, one month and 25 months of storage, using a photometric method (d-ROMs test). Measurements were performed in aliquots thawed only once at each time point and in aliquots frozen and thawed repeatedly over the study period. After two years we observed a small but statistically significant 4% decrease in the hydroperoxide concentration, which was substantially unaffected by storage temperatures and repeated freeze-thaw cycles. We also carried out the d-ROMs test in sera from ten apparently healthy volunteers at 2, 8, 24, and 48 hours after collection and storage at 4 degrees C and did not observe any significant variation. In conclusion, the d-ROMs test is a simple method suitable to evaluate the free radical activity in frozen serum samples after long-term storage.

Adult↗

PubMedDate not supplied

[Drugs for "well-being". Drugs and biotechnology as instruments of self-programming?].

New drugs are being released on the market with the alluring promise of a better quality of life. Together with the "magic" pills already available, as amphetamines, benzodiazepines and antidepressants, Viagra and new compounds to control lipid metabolism, appear to open new avenues to individual self-determination and self-improvement. Also new biotechnological resources allow today a far more manipulated control of procreation. Designed to target specific groups of patients with well-defined psycho-physiological problems, these new drugs and biotechnologies are becoming available to the larger public. Incorrect information by the mass media, insufficient control by some physicians and self-promoting attitudes in healthy subjects may combine into a powerful cocktail, creating confusion and leading to an incorrect use of these drugs. Can individuals really improve themselves in this fashion or are they just abusing drugs for their own purposes? Are the costs of these drugs and procedures socially justified?

Biotechnology↗

PubMedDate not supplied

Premenopausal breast cancer patients treated with a gonadotropin-releasing hormone analog alone or in combination with an aromatase inhibitor: a comparative endocrine study.

BACKGROUND: The combination of a GnRH analogue and an aromatase inhibitor can induce a complete estrogen blockade in premenopausal breast cancer patients. MATERIAL AND METHODS: Twenty-one premenopausal women with advanced breast cancer were randomised to receive the GnRH analog triptorelin (3.75 mg i.m. monthly; n = 10) alone or in combination with the aromatase inhibitor formestane (4-OHA, 500 mg i.m. fortnightly; n = 11) to compare the effect of both treatments on the patients' estrogenic milieu. Therefore, serum estrogen, gonadotropin and sex hormone-binding globulin (SHBG) levels were investigated before the start of treatment and subsequently over a three-month period. RESULTS: There was a significant between-group difference in estrogen suppression during therapy. In comparison with baseline values, after four weeks of treatment the estradiol levels decreased by an average of 86.9% (95% CI, 70.5-94.2%) in the group treated with triptorelin alone and by 97.3% (95% CI, 94.1-98.8%; P = 0.0422) in the combination group; the respective figures for estrone were 48.5% (95% CI, 27.5-63.5%) and 70.4% (95% CI, 52.3-81.6%; P = 0.0007) and for estrone sulfate 56.7% (95% CI, 40-68.8%) and 80.5% (95% CI, 69.4-87.6%; P = 0.0055). No difference was observed between the groups in terms of gonadotropin suppression; both treatment modalities led to a slight but delayed decrease in SHBG levels. Three of the patients treated with triptorelin alone experienced tumor regression compared with four patients in the combination group. No appreciable side effects of the combination therapy were observed. CONCLUSION: The treatment of premenopausal patients with triptorelin plus 4-OHA is feasible and leads to a much greater inhibition of main circulating estrogens than treatment with the analog alone. Since the combination of a GnRH analog and an aromatase inhibitor might potentially enhance the anti-tumor efficacy of the analog alone owing to more favorable endocrine effects, such a therapeutic approach deserves more extensive evaluation in the clinical setting.

Adult↗

PubMedDate not supplied

Serum evaluation of P53 protein in patients with gynaecological cancer.

Sera from patients with gynaecological cancer including the ovary, endometrium or cervix were examined for p53 protein, using the Pantropic p53 quantitative ELISA. Patients with benign gynaecological pathologies were included as a control group. p53 values ranged from undetectable to high levels of the protein (range: 0-531 pg/ml). Using the value of 200 pg/ml as the cut-off, p53 serum levels were found to be elevated in 23% of the patients with ovarian cancer, in 16% of the patients with endometrial cancer and in 14% of the patients with cervical cancer. In the control group, increased serum p53 levels were found in 3.3% of patients. No differences were observed among the groups with different types of cancer or at different stages, but the differences between the cancer groups and the control group were statistically significant. Our results suggest that serum p53 evaluation could be an adjunctive tool to the diagnostic laboratory tests for preoperatively gynaecological cancers and both a competitive and alternative useful procedure for the detection of p53 gene mutations.

Adult↗