Neural network analysis in predicting 2-year survival in elderly people: a new statistical-mathematical approach

We designed this study to test the usefulness of artificial neural networks (ANN) in assessing 2-year survival in elderly persons, and to understand the net's logical functioning, thus determining the relative importance of the single biological and clinical variables which influence survival. ANN are statistical-mathematical tools able to determine the existence of a correlation between series of data and, once 'trained', to predict output data given input data. Although ANN have been applied in various areas of medical research, they have only very recently been applied in geriatrics (Cacciafesta et al., 2000. Arch. Gerontol. Geriatr. 31 (in press)). We built up an ANN to investigate how 17 clinical variables relating to a sample of 159 elderly people affect survival, and the possibility of predicting 2-year survival or non-survival for each single subject. When tested on a sample of 20 elderly people, the trained network gave the correct answer in 85% of the cases. We then extracted the mathematical function that the net used for calculating the output (survival) for each set of input data (clinical variables). Using this formula, we investigated how some clinical variables influence 2-year survival: we found that a low serum cholesterol level is an unfavourable characteristic in relation to survival. We conclude-despite the fact that the sample studied was relatively small-that ANN are useful in predicting 2-year survival in elderly people. The mathematical function we obtained from the net seems useful in determining the relative importance of single variables related to survival.     

The use of Percoll gradients for the preparation of subpopulations of human spermatozoa

Centrifugation of human spermatozoa on BWW- or HEPES-Krebs-Ringer-buffered media containing Percoll as a method to prepare pure gamete populations or subpopulations has been studied in detail. Application of this technique (Gorus & Pipeleers 1981) allowed us to obtain uncontaminated, motile spermatozoa and, after a subsequent Percoll gradient step, resulted in the enrichment of motile cells able to readily penetrate in vitro into AB-serum filled capillaries. The gradient sedimentation patterns of 25 different sperm samples with normal seminal parameters were found to be strongly influenced by the characteristics of the sample itself and also by the buffer used for filtration. However, the present study also revealed that ultrastructural changes and the release of intraspermatozoal enzymes were induced by the procedure. It is concluded that, although of interest clinically, the Percoll filtration technique in its present form is probably of limited value for cell biological and/or ultrastructural studies.     

Salvage treatment for local or local-regional recurrence after initial breast conservation treatment with radiation for ductal carcinoma in situ

The present study evaluated the outcome of salvage treatment for women with local or local-regional recurrence after initial breast conservation treatment with radiation for mammographically detected ductal carcinoma in situ (DCIS; intraductal carcinoma) of the breast. The study cohort consisted of 90 women with local only first failure (n=85) or local-regional only first failure (n=5). The histology at the time of recurrence was invasive carcinoma for 53 patients (59%), non-invasive carcinoma for 34 patients (38%), angiosarcoma for one patient (1%), and unknown for two patients (2%). The median follow-up after salvage treatment was 5.5 years (mean=5.8 years; range=0.2-14.2 years). The 10-year rates of overall survival, cause-specific survival, and freedom from distant metastases after salvage treatment were 83%, 95%, and 91%, respectively. Adverse prognostic factors for the development of subsequent distant metastases after salvage treatment were invasive histology of the local recurrence and pathologically positive axillary lymph nodes. These results demonstrate that local and local-regional recurrences can be salvaged with high rates of survival and freedom from distant metastases. Close follow-up after initial breast conservation treatment with radiation is warranted for the early detection of potentially salvageable local and local-regional recurrences.     

Behavioral differences between subgroups of rats with high and low threshold to clonic convulsions induced by DMCM, a benzodiazepine inverse agonist

In epileptic patients, there is a high incidence of psychiatric comorbidities, such as anxiety. Gamma-aminobutyric acid (GABA) ionotropic receptor GABA(A)/benzodiazepine allosteric site is involved in both epilepsy and anxiety. This involvement is based on the fact that benzodiazepine allosteric site agonists are anticonvulsant and anxiolytic drugs; on the other hand, benzodiazepine inverse agonists are potent convulsant and anxiogenic drugs. The aim of this work was to determine if subgroups of rats selected according to their susceptibility to clonic convulsions induced by a convulsant dose 50% (CD50) of DMCM, a benzodiazepine inverse agonist, would differ in behavioral tests commonly used to measure anxiety (elevated plus-maze, open field) and depression (forced swimming test). In the first experiment, subgroups of adult male Wistar rats were selected after a single dose of DMCM and in the second experiment they were selected after two injections of DMCM given after an interval of 1 week. Those rats presenting full clonic convulsions were termed Low Threshold rats to DMCM-induced clonic convulsions (LTR) and those not having clonic convulsions High Threshold rats to DMCM-induced clonic convulsions (HTR). In both experiments, only those rats presenting full clonic convulsions induced by DMCM and those not showing any signs of motor disturbances were used in the behavioral tests. The results showed that the LTR subgroup selected after two injections of a CD50 of DMCM spent a significantly lower time in the open arms of the elevated plus-maze and in the off the walls area of the open field; moreover, this group also presented a higher number of rearings in the open field. There were no significant differences between HTR and LTR subgroups in the forced swimming test. LTR and HTR subgroups selected after only one injection of DMCM did not differ in the three behavioral tests. To verify if the behavioral differences between HTR and LTR subgroups of rats selected after two injections of DMCM were due to the clonic convulsion, another experiment was carried out in which subgroups of rats susceptible and nonsusceptible to clonic convulsions induced by a CD50 of picrotoxin, a GABA(A) receptor channel blocker, were selected and submitted to the elevated plus-maze and open field tests. The results obtained did not show any significant differences between these two subgroups in the elevated plus-maze and open field tests. In another approach to determine the relation between fear/anxiety and susceptibility to clonic convulsions, subgroups of rats were selected in the elevated plus-maze as more or less fearful/anxious. The CD50 for clonic convulsions induced by DMCM was determined for each of these two subgroups. The results showed a significantly lower CD50 for the more fearful/anxious subgroup, which means a higher susceptibility to clonic convulsions induced by DMCM. The present findings show a relation between susceptibility to clonic convulsions and fear/anxiety and vice versa which may be due to differences in the assembly of GABA(A)/allosteric benzodiazepine site receptors in regions of the brain.     

Long-term outcome after breast-conservation treatment with radiation for mammographically detected ductal carcinoma in situ of the breast

BACKGROUND: Ductal carcinoma in situ (DCIS) is detected most commonly on routine screening mammography in the asymptomatic patient, and has a long natural history. The objective of the current study was to determine the long-term outcome after breast-conservation surgery followed by definitive breast irradiation for women with mammographically detected DCIS of the breast. METHODS: In total, 1003 women with unilateral, mammographically detected DCIS of the breast underwent breast-conserving surgery followed by definitive breast irradiation. These women were treated in 10 institutions in North America and Europe. The median follow-up was 8.5 years (mean, 9.0 years; range, 0.2-24.6 years). RESULTS: The 15-year overall survival rate was 89%, and the 15-year cause-specific survival rate was 98%. The 15-year rate of freedom from distant metastases was 97%. In total, there were 100 local failures (10%) in the treated breast. The 15-year rate of any local failure was 19%, and the 15-year rate of local only first failure was 16%. Patient age > or = 50 years at the time of treatment and negative final pathology margins from the primary tumor excision both were associated independently with a lower risk of local failure in univariate analysis (P = 0.00062 and P = 0.024, respectively) and in multivariate analysis (P = 0.00057 and P = 0.0026, respectively). For favorable subgroups of patients age > or = 50 years or with negative resection margins, the 10-year risk of local failure was < or = 8%. CONCLUSIONS: The current results support the use of breast-conserving surgery followed by definitive breast irradiation for the treatment of patients with mammographically detected DCIS of the breast. Patient age > or = 50 years at the time of treatment and negative resection margins both were associated independently with a decreased risk of local failure.     

Randomized study on oral administration of calcitriol to prevent symptomatic hypocalcemia after total thyroidectomy

BACKGROUND: Symptomatic hypocalcemia remains the main postoperative complication after total thyroidectomy. The aim of the present study was to evaluate the role of oral supplementation of calcitriol and calcium salts in preventing severe postoperative hypocalcemia after total thyroidectomy. METHODS: A consecutive series of patients undergoing total thyroidectomy followed by administration of 500 mg of calcium salts 3 times per day were randomized to 3 different postoperative medical treatments: in group A, .5 microg of calcitriol twice per day was administered to 104 patients; in group B, 1 mmicrog of calcitriol twice per day was administered to 111 patients; and in group C, 202 patients did not receive calcitriol. RESULTS: The rate of postoperative tetany in group A was 2.9%, in group B was 0%, and in group C was 7.4% (P=.03) and the rate of paresthesias was 28.8%, 17.1%, and 22.3%, respectively (P=.19). At discontinuation of calcitriol/calcium salts treatment, intact parathyroid hormone levels did not significantly differ from the preoperative levels. Receiver operating characteristic (ROC) curve analysis showed that the area under the curve for serum concentration of calcium in predicting postoperative tetany was .749, .858 and .862 on the first, second, and third postoperative day, respectively. The best cut-off value of calcemia for prediction tetany was 7.5 mg/dL, and the rate of severe hypocalcemia on the third postoperative day was 23.1% in group A, 9.9% in group B, and 27.2% in group C (P=.001). CONCLUSIONS: Oral administration of 1 microg of calcitriol twice per day and 500 mg of calcium salts 3 times per day after total thyroidectomy significantly decreases the risk of severe postoperative hypocalcemia.