Induced attack was studied under three conditions: (1) paired experimentally naive rats were exposed to intense electrical shock; (2) experimental subjects, previously trained to respond on a fixed vii ratio of six responses for liquid food reinforcement, were paired with target animals with the reinforcement contingency in effect; (3) experimental subjects were given a history of responding on a fixed ratio of six responses for positive reinforcement in the presence of shock, and finally this group was paired with experimentally naive targets when both the reinforcement and shock variables were present. Pairing experimental animals without shock did not cause attack, nor was bar-pressing behavior appreciably disrupted. Only when electrical shock was imposed upon pairs did attack occur. Furthermore, attack behavior severely reduced operant responding and there appeared to be no recovery of response rates over several sessions.

<p>Sprovedena studija po prvi put izve&scaron;tava o prisustvu patulina, sekundarnog metabolita određenih vrsta plesni, u proizvodima od jabuka, kao i proceni rizika usled unosa patulina od strane odojčadi, dece, adolescenata i odrasle populacije u Republici Srbiji. Ukupno 356 uzoraka sokova i ka&scaron;ica za odojčad i malu decu (48 i 66, redom), sokova za decu (mala pakovanja sa cevčicom, 100) i sokova u porodičnom pakovanju (142), sakupljeno je sa trži&scaron;ta tokom tri godine i analizirano primenom tečne hromatografije sa ultraljubičastom detekcijom, metodom koja je predhodno validirana. Prisustvo patulina je detektovano u 44% i 17% uzoraka sokova i ka&scaron;ica za odojčad i malu decu, redom, u količinama nižim od zakonskog ograničenja od 10 &mu;g/kg (maksimalno 8,3 i 7,7 &mu;g/kg, redom). Udeo kontaminiranih uzoraka među sokovima za decu iznosio je 43%, sa najvi&scaron;om koncentracijom patulina od 30,2 &mu;g/kg ispod maksimalno dozvoljenog nivoa od 50 &mu;g/kg. Patulin je detektovan u 51% sokova u porodičnom pakovanju, sa 0,7% uzoraka iznad zakonske granice od 50 &mu;g/kg (prosečna koncentracija 4,3 &mu;g/kg). Sokovi od jabuka su pokazali značajno vi&scaron;i udeo kontaminiranih uzoraka (74% u odnosu na 28%), kao i vi&scaron;i prosečni sadržaj patulina (6,4 u odnosu na 2,1 &mu;g/kg) u poređenju sa sokovima od me&scaron;anog voća. Procena rizika usled unosa patulina od strane odojčadi, dece, adolescenata i odrasle populacije u Republici Srbiji, sprovedena primenom determinističkog i probabilističkog pristupa, uključujući rezultate biodostupnosti patulina, pokazala je da je odnos između procenjenog dnevnog unosa i toksikolo&scaron;ke referentne doze za patulin od 0,4 &mu;g/kg telesne mase, koji se označava kao &ldquo;hazard quotient&rdquo;, znatno ispod 1, &scaron;to ukazuje na tolerantan nivo izloženosti i nepostojanje razloga za zabrinutost za zdravlje populacije. Dodatno, analiza ostataka pesticida i toksičnih metala potvrdila je bezbednost proizvoda od jabuka na trži&scaron;tu. Međutim, identifikacija vi&scaron;estrukih ostataka pesticida je razlog za aktivan pristup i pažljivo planiranje i sprovođenje monitoringa bezbednosti hrane, posebno hrane za odojčad i malu decu, kao najosetljivije populacione grupe.</p> / <p>This study reports for the first time the occurrence of patulin, a secondary metabolite of certain fungi, in apple-based food, as well as risk assessment related to patulin intake by infants, children, adolescents and adults in Serbia. In total, 356 samples of infant fruit juices (48), infant pur&eacute;e (66), juices for children (small package with straw, 100), and juices in family package (142) were collected from the market over three years (2013&ndash;15) and analysed using validated method based on liquid chromatography with ultraviolet detection. Patulin was found in 44% of infant juices and 17% of infant pur&eacute;e, with all values below the legal limit of 10 &mu;g/kg (maximum 8.3 and 7.7 &mu;g/kg, respectively). The proportion of contaminated samples among fruit juices for children was 43%, with the highest patulin concentration at 30.2 &mu;g/kg, not exceeding the maximum allowed level of 50 &mu;g/kg. Patulin was found in 51% of juices in family package, with 0.7% of the samples in excess of the legal limit of 50 &mu;g/kg (mean 4.3 &mu;g/kg). Apple juices showed significantly higher percentage of contaminated samples (74% versus 28%), as well as higher mean patulin content (6.4 versus 2.1 &mu;g/kg) when compared with the multifruit ones. Risk assessment of patulin intake by Serbian infants, children, adolescents and adults, conducted by deterministic and probabilistic approaches and including the bioaccessibility results, revealed a ratio between exposure and toxicological reference dose for patulin of 0,4 &mu;g/kg body weigth, called hazard quotients, well below 1, indicating a tolerable exposure level and no health concern. Furthermore, analysis of pesticide residues and toxic metals confirmed safety of apple products on the market. However, identification of multiple pesticide residues is a reason for an active attitude and carefully planned and conducted monitoring of food safety, expecialy in the case of food for infants and young children, as they are the most susceptible population group.</p>