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Biomedical subjects

A Arak

Publications and source records attributed to A Arak.

6 recordsLinked to original sources
PubMed1996

Gastric cancer: surgical management and prognosis.

The experience of the Department of Surgery of Oulu University Hospital, Finland, in the treatment of 203 consecutive patients (129 men and 74 women, mean age 64.9 years) with primary gastric cancer during the five-year period from 1983 to 1987 is reviewed. 196 (96.6%) patients underwent surgery; radical gastrectomy with limited lymphadenectomy in 88 (43.3%) cases, palliative gastric resections in 47 (23.3%) cases and symptomatic bypass procedures in 27 (13.3%) cases. Postoperative complications occurred more frequently after total than after subtotal gastrectomy. Overall postoperative mortality was 9.2%. The five-year survival was 21.1% for all patients and 45.5% for curatively operated patients. Univariate analysis indicated that tumour size, location, gross appearance, degree of gastric wall invasion, presence of lymph node and/or distant metastases, and operative procedures were the significant prognostic factors of survival. In a Cox multivariate analysis on the T stage and presence of distal metastases independently affected survival. Our results show that besides early detection, the standardisation of surgical procedures (extent of gastrectomy and lymphadenectomy) as well as substantial decrease in postoperative complications and mortality rates are of importance in the improvement of the outcome of surgery for gastric cancer.

Adult↗
PubMed1995

Conflict, receiver bias and the evolution of signal form.

In a model, conflicts of interest between communicating individuals are shown to have an important influence on the cost and form of signals that evolve. Two types of conflict are considered: competition between senders to obtain a response from the receiver, and conflict between the sender and the receiver. The receiver system is modelled as an artificial neural network whose 'resistance' to signals is represented as a motivational factor that varies independently of the signal. Biases in the receiver system act as the selective force on signals, causing them to become more costly and conspicuous as the intensity of conflict increases. There is some evidence that competition between senders and sender-receiver conflict may have qualitatively different outcomes. We give examples of some situations to which the model might be applied and point out some predictions that could be tested empirically.

Animal Communication↗
PubMed1994

Symmetry, beauty and evolution.

Humans and certain other species find symmetrical patterns more attractive than asymmetrical ones. These preferences may appear in response to biological signals, or in situations where there is no obvious signalling context, such as exploratory behaviour and human aesthetic response to pattern. It has been proposed that preferences for symmetry have evolved in animals because the degree of symmetry in signals indicates the signaller's quality. By contrast, we show here that symmetry preferences may arise as a by-product of the need to recognize objects irrespective of their position and orientation in the visual field. The existence of sensory biases for symmetry may have been exploited independently by natural selection acting on biological signals and by human artistic innovation. This may account for the observed convergence on symmetrical forms in nature and decorative art.

Animals↗
PubMed1994

Factors influencing survival of patients after radical surgery for gastric cancer. A regional study of 406 patients over a 10-year period.

The present retrospective report presents a review of prognostic factors influencing the survival of 406 gastric cancer patients radically operated on in the Tartu Oncology Hospital, Estonia in 1978-1987. All patients underwent total (n = 170) or subtotal (n = 236) gastrectomies with extensive lymphadenectomy (260 R2- and 146 R3-resections) according to the General Rules for the Gastric Cancer Study in Surgery and Pathology established by the Japanese Research Society for Gastric Cancer, introduced in our hospital at the end of the 1970s and now used as the unavoidable procedure for curative gastric cancer surgery. The 30-day postoperative mortality was 5.9% and the overall 5-year survival 46.1%. The male:female ratio was 0.95 and the mean age 62.4 years. Only 7.6% of all our patients operated on had early gastric cancer with a 5-year survival of 80.7% whereas 76.8% had T3-T4 tumours with a 5-year survival of 41.0%. Lymph node involvement was found in 44.6% of the patients. Independent favourable prognostic factors were (the 5-year survivals are presented within parentheses): limited (N0-N1) lymph node involvement (56.4 vs. 22.6%), pT 1-2 stage (62.8 vs. 41.0%), papillary, tubular or poorly differentiated histological pattern (51.9 vs. 33.1%), subtotal gastrectomy (55.9 vs. 32.4%) and age below 70 years (51.9 vs. 35.2%). Sex of patients, Borrmann type, size and site of tumour were not statistically associated with prognosis at multivariate analysis. Our results also suggested that besides predetermined prognostic factors, the surgical policy had a great impact on the prognosis of gastric cancer patients. We conclude that gastrectomy with combined resections of neighbouring organs directly invaded and with extensive lymphadenectomy at least up to the second node group might be the procedure of choice for advanced gastric cancer.

Adult↗
PubMed1993

Selection of exaggerated male traits by female aesthetic senses.

Darwin suggested that many apparently deleterious secondary sexual characters in males, such as bright colours, elaborate ornaments and conspicuous displays, evolved as a result of female choice. Darwin never tried to explain the crucial agent of selection, that females have preferences for exaggerated male traits. Rather, he took it for granted that females of many species possess a 'sense of the beautiful', akin to the aesthetic sense in humans. The question of why such preferences evolve remains a controversial issue. Here we report that mechanisms concerned with signal recognition possess inevitable biases in response that act as important agents of selection on signal form. The existence of such biases may be sufficient to explain the evolution of exaggerated male secondary sexual traits, and elaborate signals in general.

Animals↗