bluuebunny/crossref_metadata_2025 huggingface dataset:
A estabilidade do avanço mandibular cirúrgico por meio da osteotomia bilateral sagital: uma revisão
Authors: Siqueira Danilo Furquim , Castro Aline Maria Alencar de , Santos Júnior José Antônio dos , Maltagliati Liliana Ávila , Angelieri Fernanda
Published: November 2007

INTRODUÇÃO: a Osteotomia Sagital Bilateral Mandibular (OSBM) é a cirurgia de escolha da maior parte dos cirurgiões para a correção de discrepâncias esqueléticas mandibulares no sentido sagital. Contudo, sua estabilidade permanece controversa na literatura. OBJETIVO: neste trabalho, analisaram-se criteriosamente os vários fatores relacionados com a sua estabilidade em longo prazo, como a quantidade de avanço mandibular, o tipo de fixação, a utilização ou não de splints cirúrgicos, o posicionamento condilar, além de outros itens. CONCLUSÃO: baseado na literatura consultada, concluiu-se que a magnitude dos movimentos sagitais mandibulares deverá ser menor do que 10mm; que a fixação rígida deverá ser escolhida em vez da semi-rígida; que a utilização de splints deverá ser evitada ou feita por tempo reduzido; e que os tratamentos ortodônticos pré e pós-cirúrgicos são essenciais para a obtenção de resultados satisfatórios.
Análise genética de problemas craniofaciais: revisão da literatura e diretrizes para investigações clínico-laboratoriais (parte 2)
Authors: Cruz Ricardo Machado , Oliveira Silviene Fabiana de
Published: November 2007

OBJETIVO: esse artigo tem como objetivo ser uma fonte de informação acerca das técnicas e análises genéticas mais utilizadas em investigações clínicas e laboratoriais visando a identificação e a caracterização de genes relacionados a doenças ou distúrbios complexos, especialmente os que atingem as estruturas do crânio e da face. METODOLOGIA: são traçadas algumas diretrizes para guiar os futuros pesquisadores nos processos de seleção de amostras e obtenção de heredogramas para estudos genéticos e fornecidos conceitos e princípios gerais que norteiam métodos de análises genéticas. Tais métodos exigem conhecimento a respeito de transmissão gênica, genética molecular e utilização de marcadores moleculares, assim como envolvem o domínio de técnicas laboratoriais como, por exemplo, reações de polimerização em cadeia (PCR), eletroforese e seqüenciamento de DNA. RESULTADOS E CONCLUSÕES: as análises genéticas, em especial as análises de segregação e de ligação, representam importantes ferramentas à disposição dos pesquisadores na tentativa de relacionar fenótipos a genes específicos e na busca da exata localização cromossômica dos mesmos. Espera-se com esse artigo que os cirurgiões-dentistas clínicos possam começar a perceber a importância do assunto e buscar se aprofundar nessa área.
Cirurgia ortognática de modelos: protocolo para mandíbula
Authors: Sant'Ana Eduardo , Rodrigues Moacyr Tadeu Vicente , Ferreira Gabriel Ramalho , Gurgel Júlio de Araújo
Published: November 2007

INTRODUÇÃO: o ensaio em modelos de gesso tem grande importância para o planejamento em cirurgia ortognática. OBJETIVO: neste artigo, será apresentado, passo-a-passo, uma técnica de cirurgia de modelos iniciando pela mandíbula, destacando aspectos importantes e as vantagens deste procedimento.
Gastos em saúde e incidência de benefício no município de Senhor do Bonfim (BA) em 2003
Authors: Aragão Erika , Santos Luciano Damasceno , Loureiro Sebastião , Nunes Mônica , Almeida Isaura F. Gottschall de , Souza Ricardo Luciano Silva Pereira de
Published: November 2007

O objetivo deste artigo é analisar a desigualdade no acesso e utilização dos serviços de saúde no município de Senhor do Bonfim (BA). O método utilizado é o "benefit incidence", ou incidência de benefício, que permite identificar quais os grupos sociais que se beneficiam dos gastos do Governo. A incidência de benefício no município de Senhor do Bonfim, para 2003, foi estimada por grupos da população previamente definidos (renda, gênero e cor da pele), com o objetivo de avaliar o grau de iniqüidade dos gastos públicos em saúde. Os gastos públicos foram desagregados por nível de complexidade. Combinando os dados referentes aos subsídios com os resultados da pesquisa domiciliar, observou-se iniqüidade da distribuição dos gastos públicos com saúde em Senhor do Bonfim.
Taxa de juros e prêmio de risco: investigando a hipótese Bresser-Nakano para a economia brasileira, 1995-2005
Authors: Marques André M. , Fochezatto Adelar
Published: November 2007

A proposta Bresser-Nakano deflagrou uma forte discussão sobre a política de juros no Brasil, suscitando uma série de críticas e contribuições para o seu aperfeiçoamento. Seu argumento central baseia-se na suposição de que o sentido da causalidade vai da taxa de juros para o prêmio de risco, e não o contrário. Com isso, a autoridade monetária, ao reduzi-la, promove um círculo virtuoso na economia, reduzindo o prêmio de risco e, através da taxa de câmbio, a própria inflação. Essa hipótese, no entanto, continua controversa e carece de estudos empíricos visando à sua verificação. O objetivo principal deste trabalho é investigar a sua validade para a economia brasileira nos últimos 10 anos de política monetária. Aplicando testes de causalidade de Granger, os resultados encontrados apóiam a hipótese Bresser-Nakano.
Histeria e feminilidade
Authors: Michels André
Published: November 2007

Discute-se a feminilidade nos dias de hoje a partir da abertura discursiva introduzida pelos estudos sobre a histeria, de Freud. A própria definição da clínica psicanalítica é remetida às modalidades de defesa contra a posição feminina e ao que ela veicula de diferença radical, aqui associada à castração. Mediante apresentação de uma "nota" clínica, aborda-se a feminilidade frente à inscrição e à relação dos sexos, evidenciando-se a função simbólica de uma mãe. A posição feminina na transmissão é tratada pelo viés da nomeação. A pesquisa clínica sobre a histeria indica que a posição feminina submetida à castração simbólica revela-se condição da flexão do nome e produção de diferença.
Freud, Jung e o Homem dos Lobos: percalços da psicanálise aplicada
Authors: Endo Paulo
Published: November 2007

Pretende-se examinar o papel da analogia no pensamento freudiano, através de um período fértil e tumultuado do movimento psicanalítico, marcado pela intensificação das divergências entre Freud e seu dileto (Jung), e também pelo crescimento do movimento da psicanálise aplicada entre Freud e seus discípulos e pelo trabalho analítico daquele que é, talvez, o mais importante caso clínico escrito por Freud: o caso do Homem dos Lobos. Este período marca um imenso campo de debates clínicos e teóricos, entre os quais se inclui, sem dúvida, o problema da analogia na teoria e na clínica psicanalíticas.
Objeto a e privação: Um caso de retroação significante na teoria psicanalítica
Authors: Pellion Frédéric
Published: November 2007

Desenvolve-se a hipótese de que a elaboração da "categoria" particular de "falta de objeto" que é a privação, feita por Lacan ao longo do quarto ano de seu Seminário, não apenas antecipa a "invenção" ulterior do objeto a, como também se revela, a posteriori, algo que lhe é necessariamente prévio.
A maternidade sob a ótica da teoria pulsional
Authors: Gómez Graciela Quintana
Published: November 2007

Pretende-se demonstrar que os diversos modos de entendimento da origem do psiquismo, presentes em determinados textos da metapsicologia freudiana, vinculam-se a diferentes formas de compreensão do tema da maternidade. Assim, em "Pulsões e seus destinos" (1915), a maternidade é associada a uma excitação externa que desorganiza o psiquismo do recém-nascido; por sua vez, em "Além do princípio do prazer" (1920) e "O problema econômico do masoquismo" (1924), há elementos de análise que possibilitam uma leitura alternativa sobre o tema, a partir das noções de masoquismo erógeno, pulsão de vida e de morte.
Apresentação de pacientes: (re)descobrindo a dimensão clínica
Authors: Ferreira Cristiana Miranda Ramos
Published: November 2007

Nos últimos anos, a prática da apresentação de pacientes vem crescendo no campo psicanalítico, e isto se deve, sem dúvida, aos incontestáveis efeitos clínicos por ela produzidos. Para se fazer uma análise crítica e avançar nas elaborações e sistematizações acerca da apresentação, é preciso conhecer as bases conceituais sobre as quais o processo se deu. Procura-se, aqui, esboçar um mapeamento histórico, procurando identificar as circunstâncias de seu surgimento, transformações pelas quais passou, até seu uso no momento atual.
Differential capacity of nitrogen assimilation between apical and basal leaf portions of a tank epiphytic bromeliad
Authors: Takahashi Cassia A. , Ceccantini Gregório C.T. , Mercier Helenice
Published: November 2007

The leaf is the main organ of the vegetative body of tank epiphytic bromeliads, which may be subdivided into apical and basal parts. Little is known about the existence of morphological, anatomical or physiological differences between these two leaf portions. The objective of this study was to verify the existence of a differential capacity to assimilate nitrogen from urea between basal and apical leaf portions of Vriesea gigantea, a tank epiphytic bromeliad. Plants were cultivated in vitro in the presence of 5 mM urea for 15 days. During this period, the activities of the enzymes glutamine synthetase (GS, EC 6.3.1.2) and NADH-dependent glutamate dehydrogenase (NADH-GDH, EC 1.4.1.2) were quantified, as well as the densities of trichomes and stomata found at the leaf surface of both regions. The highest activities of GS and NADH-GDH were always detected at the top portion, and on the 3rd day of in vitro cultivation an increase in these activities was detected. An inverse correlation between number of trichomes and stomata in these two leaf portions was verified: the top region presented 30% less trichomes and twice as many stomata as the basal region. This suggests that the upper region of the leaf may be preferentially involved with the assimilation of nitrogen from urea via GS and NADH-GDH, whereas the basal region may be involved with its absorption. This is the first study to report that ammonium assimilation may take place preferentially in a specific portion of tank-forming bromeliad leaves.
Presence of the cytolytic protein enterolobin in different developmental stages of Enterolobium contortisiliquum seeds
Authors: Lima Consuelo M. R. de , Zanotta Pedro J. P. , Ricart Carlos A. O. , Sousa Marcelo V. de
Published: November 2007

Enterolobin is a 52.9 kDa, cytolytic, inflammatory and insecticidal protein present in Enterolobium contortisiliquum (Vell.) Morong, a Brazilian large-sized tree. This protein was previously described to occur in different forms of association (monomeric and oligomeric forms). In the current work, we investigated the presence of enterolobin forms of association and hemolytic activity in maturing, germinating and germinated seeds. Immunoblotting analysis revealed the presence of the monomeric form of enterolobin in all phases under study, whereas the dimer was detected in developing seeds in the second half of the maturation period, during germination and in the early post-germination phase. The trimeric form of enterolobin appeared one week after the dimer and could be detected up to half of the average germination time of the E. contortisiliquum seeds. The highest hemolytic titers due to enterolobin activity were found in mature and germinating seeds. Apparently, there was no modification in molecular mass of the enterolobin monomer during seed maturation and germination, suggesting the absence of a precursor form. The results also show that enterolobin was not utilized in germination and initial post-germination phases, which are critical in development and seedling establishment. Enterolobin availability could enable it to perform an important physiological role, including plant defense.
A fossil loricariid catfish (Siluriformes: Loricarioidea) from the Taubaté Basin, eastern Brazil
Authors: Malabarba Maria Claudia , Lundberg John G.
Published: November 2007

A new loricariid catfish is described from the Tremembé Formation (Late Oligocene to Early Miocene) sediments of the Taubaté Basin in eastern São Paulo State, Brazil. Taubateia paraiba, new genus and species, is based on a single specimen preserved as a ventral-side impression of an articulated partial neurocranium, dorsal elements of the pectoral girdle and anterior vertebrae. The fossil is identified as belonging to family Loricariidae based on obvious overall similarity and the presence of diagnostic derived characters such as: odontodes, dorsal margin of metapterygoid contacting lateral ethmoid, presence of mesethmoid disk (condyle), and compound pterotic-supracleithrum bone. Also, as in most loricariids, the ossified transcapular (Baudelot's) ligament plus basiocciptal lateral process form a prominent transverse wall at the occiput. Other derived characters preserved in Taubateia are synapomorphies at different levels within Loricariidae, including a wide and low parasphenoid, form of pterotic-supracleithrum, shape and position of the mesethmoid disk, a triangular lateral ethmoid with expanded posterolateral corner and a rounded and low ridge articulating with the metapterygoid, and a pointed distal margin of transverse process of the Weberian compound centrum. The derived characters recognized in this fossil are a distinctive combination for diagnosing a new genus and species but not for its unambiguous placements in any of the currently recognized loricariid subfamilies.
Corydoras ortegai, a new species of corydoradine catfish from the lower río Putumayo in Peru (Ostariophysi: Siluriformes: Callichthyidae)
Authors: Britto Marcelo R. , Lima Flávio C. T. , Hidalgo Max H.
Published: November 2007

A new species of Corydoras, C. ortegai, is described from tributaries of the lower course of río Putumayo in Peru, close to the border with Brazil and Colombia. The new species seems to be related to Corydoras reynoldsi, C. weitzmani, C. panda, and C. tukano, all of which share a pattern composed of uniform light ground color on body, dark bar ("mask") across orbit, and one or two large rounded blotches midlaterally on trunk. Corydoras ortegai is easily distinguished from these species, except C. panda, mainly by the absence of a midlateral trunk blotch at the dorsal-fin level, and the rounded shape of the midlateral trunk blotch at the adipose-fin level. Corydoras ortegai differs from C. panda by its greater number of lateral body plates, lack of dorsal-fin blotch, scattered chromatophores surrounding midregion of cleithrum, caudal fin with series of small blotches restricted to rays, slenderer body, and narrower intercleithral area. Corydoras ortegai belongs to a putatively monophyletic assemblage of Corydoras that occurs mainly in the Western Amazon basin, C. tukano excepted. The occurrence of Corydoras tukano in the rio Tiquié (upper Negro basin) and its putative sister species, C. ortegai, in the western Amazon, together with similar distribution patterns shared by other groups of fishes, suggest a biogeographic relationship between these areas.
Comparative analysis of spermiogenesis and sperm ultrastructure in Callichthyidae (Teleostei: Ostariophysi: Siluriformes)
Authors: Spadella Maria A. , Oliveira Claudio , Quagio-Grassiotto Irani
Published: November 2007

In Corydoradinae, the presence of spermatids in the lumen of the testicular tubules together with spermatozoa suggests that spermatogenesis is of the semicystic type, whereas in Callichthyinae, sperm production occurs entirely within spermatocysts in the germinal epithelium, characterizing cystic spermatogenesis. Spermiogenesis in Callichthyinae is characterized by an initial lateral development of the flagellum, the presence of nuclear rotation to different degrees, an eccentric or medial formation of a nuclear fossa, formation of a cytoplasmic channel, and presence of centriolar migration, being more similar to type I spermiogenesis. In Corydoradinae, spermiogenesis is characterized by eccentric development of the flagellum, the absence of nuclear rotation, an eccentric nuclear fossa formation, formation of a cytoplasmic channel, and absence of centriolar migration, differing from the types previously described. The process of spermatogenesis and spermiogenesis in Corydoradinae and Callichthyinae revealed unique characters for each of these subfamilies, corroborating the hypotheses that they constitute monophyletic groups. In relation to sperm ultrastructure, the comparative analysis of the callichthyid species shows that the general characteristics found in the spermatozoa were similar, thus, reinforcing the hypothesis that the family is monophyletic.
The fish fauna of Brokopondo Reservoir, Suriname, during 40 years of impoundment
Authors: Mol Jan H. , Mérona Bernard de , Ouboter Paul E. , Sahdew Shamita
Published: November 2007

We investigated long-term changes in the fish fauna of Brokopondo Reservoir, Suriname, the first large reservoir (1560 km²) that was created in tropical rainforest. Before closure of the dam in 1964, the fish fauna of Suriname River had 172 species, high diversity and high evenness. The riverine fauna was dominated by small-sized species, but no single species was dominant in numbers. Large catfishes were dominant in biomass. Species were evenly distributed over riverine habitats: rapids, tributaries and main channel. Four years after closure of the dam, only 62 fish species were collected from Brokopondo Reservoir, but the composition of the fish fauna was still changing. The reservoir fauna in 1978 was very similar to the reservoir fauna in 2005, indicating that a stable equilibrium had been reached 14 years after closure of the dam. The reservoir fauna had 41 species, low diversity and low evenness. Most species of Suriname River and its tributaries with strict habitat requirements did not survive in Brokopondo Reservoir. Fish community structure was different among four habitats of Brokopondo Reservoir. The open-water habitat (10 species) was dominated by the piscivores Serrasalmus rhombeus, Acestrorhynchus microlepis and Cichla ocellaris and their prey Bryconops melanurus and two Hemiodus species. B. melanurus fed on zooplankton, Culicinae pupae and terrestrial invertebrates. Hemiodus fed on fine flocculent detritus, demonstrating that the detritus-based food chain was still important in late stages of reservoir development. Serrasalmus rhombeus also fed on peccaries that drowned when swimming across the large reservoir in rough weather. The shore community (27 species) was dominated by seven cichlids, but early stages and juveniles of the open-water species S. rhombeus and B. melanurus also occurred in the shore habitat. Fish biomass in the shore habitat was 66.5±59.9 kg ha-1. The cichlid Geophagus surinamensis and the characid B. melanurus had a lower biomass in Brokopondo Reservoir than in Suriname River. Serrasalmus rhombeus showed reduced body length in Brokopondo Reservoir as compared to riverine populations.
Activity, habitat use, feeding behavior, and diet of four sympatric species of Serranidae (Actinopterygii: Perciformes) in southeastern Brazil
Authors: Gibran Fernando Zaniolo
Published: November 2007

Diplectrum formosum (the sand perch), Diplectrum radiale (the aquavina), Epinephelus marginatus (the dusky grouper) and Mycteroperca acutirostris (the comb grouper) are four sympatric serranid of remarkable ecological and commercial importance. This study investigated the feeding of these four species in the São Sebastião Channel, São Paulo State (southeastern Brazil), comparing their diet, habitat utilization and morphological features related to foraging. These four serranids are opportunistic visual predators that use a total of nine different tactics to capture their preys, feed mostly on crustaceans during the day and twilight, and keep stationary and quiescent at night. The ecomorphological study was conducted to test its predictive value to infer lifestyles. It was verified that such analysis should be used carefully and must be complemented by field observations. Although morphologically and behaviorally very similar, D. formosum and D. radiale showed different preferences to the substratum type used by large individuals, which are exclusively sit-and-wait predators. On the other hand, E. marginatus displayed more sedentary habits than M. acutirostris, the most versatile predator from the studied species. The studied species of Diplectrum and E. marginatus can be regarded as benthic serranids, while M. acutirostris could be viewed as a nektobenthic species.
Trophic guilds of fishes in sandbank habitats of a Neotropical river
Authors: Pereira Poliana Ribeiro , Agostinho Carlos Sérgio , Oliveira Rafael José de , Marques Elineide Eugênio
Published: November 2007

The objective of this study was to characterize the trophic structure of the community of fishes exploiting riverine sandbank habitats. Collections were carried out during the period of October 1999 to December 2003, on six sand banks in the upper and middle portions of the Tocantins River drainage basin in central Brazil. The availability of food resources was evaluated based on the volume of the items present in the stomachs of all species. A total of 2,127 stomachs of fish belonging to 50 species were analyzed. Nine main trophic guilds grouped the local ichthyofauna according to diet. Aquatic-origin items were the preferred source for 55.5% of the groups analyzed, whereas terrestrial-origin items composed 44.4%. Items of undetermined origin (detritus and sediment), although present in 89% of the guilds, were the predominant food in only one trophic group. Terrestrial insects and fish were the food sources with the largest biomass available in the environment. Sandbank environments are homogeneous, with little shelter and food available; as a rule, the species that occupy these environments are generalists.
Population characteristics, space use and habitat associations of the seahorse Hippocampus reidi (Teleostei: Syngnathidae)
Authors: Rosa Ierecê Lucena , Oliveira Tacyana P. R. , Castro André L. C. , Moraes Luiz E. de Souza , Xavier Josias H. A. , Nottingham Mara C. , Dias Thelma L. P. , Bruto-Costa Leonardo V. , Araújo Maria E. , Birolo Alesandra B. , Mai Ana C. G. , Monteiro-Neto Cassiano
Published: November 2007

This paper provides a case study of a threatened seahorse species, Hippocampus reidi, highlighting the importance of using ecological information to assist conservation and management initiatives. Underwater visual sighting data (50 x 2m transect) gathered along the NE, SE and S portions of the Brazilian coast revealed an unequal distribution across localities, perhaps related to harvesting pressure, and a mean density of 0.026 ind.m-2. Our findings suggest some restricted spatial use by H. reidi, which was consistent with its estimated home range, and with re-sighting of specimens. Reproduction was recorded year-round, however productive peaks may exist. Components of habitat structure mostly used as anchoring points were mangrove plants, macroalgae, cnidarians, seagrass, sponges, and bryozoans. Conservation recommendations include: further characterization and mapping of habitats; assessment of availability and condition of microhabitats in selected areas, and studies on dispersal routes during initial life stages.
Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials
Authors: Casemiro Luciana Assirati , Martins Carlos Henrique Gomes , Souza Fernanda de Carvalho Panzeri Pires de , Panzeri Heitor , Ito Isabel Yoko
Published: November 2007

This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37°C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate - 389 CFU/g; Jeltrate Plus - 516 CFU/g; Jeltrate Chromatic - 135 CFU/g; Hydrogum - 1,455 CFU/g; Kromopan - 840 CFU/g; and Greengel - 59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients.
Organic micropollutants in the assessment of groundwater quality
Authors: Ivancev-Tumbas I. , Maljevic E. , Tamas Z. , Karlovic E. , Dalmacija B.
Published: November 2007

The better the quality of raw water resources, the higher the safety of drinking water supply. In the Danube river basin more than 60% of the population depends on groundwater sources. Organic micropollutants play an important role in quality assessment since they might cause different toxic effects in humans. There are two groups of organic micropollutants: regulated and non-regulated. In recent years, a lot of scientific effort was made to quantify their risks. Their occurrence is site specific and depends on social and economic factors, industry, population density, environmental conditions etc. That is why legislation intervention is required both at national and international level. This paper presents a literature review on the presence and fate of organic micropollutants that have been recently investigated in numerous projects worldwide. Special attention is paid to their mobility and risk for groundwater resources. Data on Serbian groundwater quality is presented for the period 2004–2005. In comparison with knowledge in developed countries, one can conclude that there is a general lack of data. More data about organic micropollutants presence is required, as well as identification of the pressures which lead to quality deterioration. Future quality assessment should be based on evaluated risks made considering both experience from developed countries and local conditions.
The Origin and Significance of Hyperplastic Hepatocellular Islands and Nodules in Hepatic Carcinogenesis
Authors: Goldfarb Stanley , Pugh Thomas D.
Published: November 2007

Results of many studies, summarized in this review, support the hypothesis that carcinogen-induced hepatocellular carcinomas develop from phenotypically-altered hyperplastic hepatocellular nodules; these in turn apparently arise from smaller focal collections of hyperplastic cells referred to as hepatocellular islands. The very recent recognition that phenobarbital, when administered after carcinogens, fosters the outgrowth of hepatocellular islands and carcinomas, now provides the means for studying stages of initiation and promotion in hep-atocarcinogenesis. In addition, the recognition that enzymatic alterations, particularly the acquisition of canalicular gamma glutamyl transpeptidase activity, loss of ATP'ase activity, and loss of glucose-6-phosphatase activity that characterize many islands, have been particularly useful for measuring and evaluating the growth kinetics and heterogeneity of the islands. Evidence is presented that periportal gamma glutamyl transpeptidase positive hepatocytes are considerably more abundant after four weeks of feeding .02% 2-acetyl-aminofluorene to young rats than in control animals, and that the outgrowth of these cells is fostered by a distinctive type of periportal reparative hyperplasia. The cells appear to arise from a pool of cells that are normally abundant in periportal location in young growing rats. The studies suggest that it may now be possible to develop short term in vivo bioassays for initiators, promoters, and complete carcinogens in the rodent liver.
Pathologic Effects of Purified Polybrominated Biphenyl Congeners in Rats
Authors: Akoso B. T. , Sleight S. D. , Aust S. D. , Stowe H. D.
Published: November 2007

Young male rats were fed diets containing 0, 1, 10, or 100 ppm of Firemaster (FM) BP-6 for 30 days, and the effects were compared with those caused by feeding diets containing identical amounts of either 2, 2', 4, 4', 5, 5-hexabromobiphenyl (HBB) or 2, 3', 4, 4', 5, 5'-HBB, two of the congeners contained in FM BP-6. In addition, rats were fed diets containing 0, 1, or 10 ppm of 3, 3', 4, 4', 5, 5'-HBB, a congener not in FM BP-6 but used because it is strictly a 3-methylcholanthrene (MC)-type inducer of hepatic drug metabolizing enzymes. Feed efficiency and weight gains were reduced only by 3, 3', 4, 4', 5, 5'-HBB at 10 ppm. Hepatomegaly occurred in rats given any of the chemicals. Vacuolation and enlargement of hepatocytes were observed in rats fed diets containing FM BP-6 or any of the congeners but were most prominent with 3, 3', 4, 4', 5, 5-HBB. Proliferation of smooth endoplasmic reticulum (SER), decreased rough endoplasmic reticulum (RER), and increased fat droplets were seen in hepatocytes of rats given FM BP-6. Similar but less severe changes were seen with 2, 3', 4, 4', 5, 5-HBB or 2, 2', 4, 4', 5, 5-HBB. The latter chemical produced the least severe changes. Hepatocytes of rats fed 10 ppm 3, 3', 4, 4', 5, 5'-HBB had extensive proliferation and disorganization of RER, increased fat droplets, and some proliferation of SER. Thymic and splenic atrophy associated with cortical lymphocytic depletion were observed only in rats fed 3, 3', 4, 4', 5, 5-HBB. 3, 3', 4, 4', 5, 5-HBB, which is an MC-type inducer, was the most toxic congener among the congeners studied. Apparently, 2, 2', 4, 4', 5, 5-HBB, which is the major congener in FM BP-6 and a phenobarbital (PB)-type inducer, contributes little to its toxicity. FM BP-6, a mixed (MC and PB)-type inducer, is more toxic than either 2, 2', 4, 4', 5, 5-HBB or 2, 3', 4, 4', 5, 5-HBB. However, 2, 3', 4, 4', 5, 5-HBB, a mixed-type inducer, is more toxic than 2, 2', 4, 4', 5, 5-HBB. Toxicity of FM BP-6 can be mostly attributed to its congeners with MC-type induction capability.
Effects of Purified Polybrominated Biphenyl Congeners on the Thyroid and Pituitary Glands in Rats
Authors: Akoso B. T. , Sleight S. D. , Nachreiner R. F. , Aust S. D.
Published: November 2007

Young male rats were fed diets containing 0, 1, 10, or 100 ppm of Firemaster (FM) BP-6 for 30 days and thyroidal and hypophyseal effects were compared with those caused by feeding identical amounts of either 2, 2', 4, 4', 5, 5'-hexabromobiphenyl (HBB) or 2, 3', 4, 4',5,5'-HBB, two of the congeners in FM BP-6. In addition, rats were given dietary levels of 0,1, or 10 ppm of 3,3', 4,4', 5, 5-HBB, a congener not in FM BP-6, but used because it is a 3-methylcholanthrene (MC)-type inducer of hepatic drug metabolizing enzymes. Thyroid weight was increased by 100 ppm FM BP-6 and by 1 and 10 ppm 3, 3', 4, 4', 5, 5'-HBB. Serum thyroxine concentrations were decreased by the highest dose of the same two chemicals. Extensive hyperplasia and hypertrophy of follicular cells and a lack of colloid were prominent lesions at the highest doses of each of the chemicals. The most severe ultrastructural alterations were seen at 10 ppm 3, 3', 4, 4', 5, 5'-HBB and 100 ppm FM BP-6. A dramatic increase in lysosomal bodies was seen at these doses. In addition, cytoplasmic colloid droplets were increased and microvilli were decreased. The Golgi apparatus was hypertrophied and the cisternae of the reticulum were dilated. Lesions were less severe with 2, 2', 4, 4', 5, 5-HBB and 2, 3', 4, 4', 5, 5-HBB, although more lysosomal bodies were seen with 2, 3', 4, 4', 5, 5-HBB than with 2, 2', 4, 4', 5, 5-HBB. Chromophobe cells in the pars anterior of the pituitary gland were swollen and vacuolated in rats fed diets containing 10 ppm 3, 3', 4, 4', 5, 5'-HBB. The results indicate that histologic and ultrastructural changes can occur with any of the chemicals used but the major functional and ultrastructural thyroidal changes seen in rats given FM BP-6 are most likely caused by congeners other than 2, 2', 4, 4', 5, 5-HBB or 2, 3', 4, 4, 5, 5-HBB.
Inhibition of Adenosine Triphosphatases in Vitro by Silver Nitrate and Silver Sulfadiazine
Authors: Nechay B. R. , Saunders J. P.
Published: November 2007

Inhibition of adenosine triphosphatase (ATPase) by silver nitrate (AgNO3) in vitro was studied in microsomal fractions or tissue homogenates of canine brain and kidney and human kidney. In microsomal fractions, AgNO3 was an indiscriminate inhibitor of ouabain-sensitive (Na+ + K+ ATPase) and ouabain-insensitive (Mg2+ ATPase) activities, with 50% inhibition obtaining at concentrations on the order of 10–7 to 10–6 M. Changing the concentrations of Na+, K+, H+, Mg2+, and ATP did not alter the fractional inhibition of Na+ + K+ ATPase by a constant concentration of AgNO3. An aqueous suspension of silver sulfadiazine had an inhibitory potency similar to AgNO3. It was concluded that silver gives a different pattern of Na+ + K+ ATPase inhibition than other metallic inhibitors of the enzyme so far examined.
Altered Development of Immunocompetence Following Prenatal or Combined Prenatal-Postnatal Insult: A Timely Review
Authors: Schmidt R. R.
Published: November 2007

There is an unequal distribution of interest between assessment of immunocompetence at the adult level following the administration of various agents/protocols and evaluation of immunocompetence postnatally subsequent to prenatal insult. This paper reviews the effects of dietary manipulation, selected pharmaceuticals, and certain environmental agents on the functional status of the postnatal immune system after in utero exposure to these agents and protocols. These data are discussed in light of what has also been observed for adult exposure to the same or similar experimental design. A discussion of congenital disorders of immunocompetence is also provided. Alteration in the development of postnatal immunocompetence following prenatal insult may manifest itself in several ways, some of which may reflect a permanent defect while others may be of a transient nature. In either instance, however, it behooves scientists in all arenas to (1) determine the precise nature and magnitude of such developmentally related immunologic deficits and (2) focus on the selection and standardization of the most relevant procedures to be employed in the assessment of immunocompetence.
Polypropylene: A Literature Review of the Thermal Decomposition Products and Toxicity
Authors: Purohit V. , Orzel R.A.
Published: November 2007

This report presents a comprehensive literature review of the thermal decomposition products of polypropylene evolved under pyrolytic and oxidative conditions and the acute toxicity of combustion products of this polymer. Generally, the pyrolysis products of polypropylene (300–700°C) were aliphatic saturated and unsaturated hydrocarbons. The combustion of polypropylene in air (200–600°C) produced oxygenated hydrocarbons, aromatic hydrocarbons, aliphatic hydrocarbons, CO, CO2, and H2O. In general, as combustion temperature and time increased, the proportions of oxygenated and aliphatic hydrocarbons decreased, whereas the proportion of aromatic hydrocarbons increased. Using the University of San Francisco/National Aeronautical and Space Administration (USF/NASA) method under the fixed temperature program, time to death in mice caused by the combustion products of polypropylene decreased as the temperature was increased. Under the rising temperature mode, time to death decreased when polypropylene was combusted under airflow as compared to no airflow conditions. CO levels generated by the combustion of polypropylene were sufficient to produce the lethal effects observed. Using a test method developed at the University of Michigan, the combustion products of polypropylene were found to be 26 times more toxic under dynamic conditions (rising temperature) than under static conditions (fixed temperature).
A Straightforward Method for the Study of Drug Interactions: An Isobolographic Analysis Primer
Authors: Gessner Peter K.
Published: November 2007

The study of drug interactions presents investigators with questions about both experimental design and interpretation of results that easily can become complex and confusing. Among the advantages of the isobolographic method is that it leads to rational experimental design and renders both the descriptive and analytical considerations of results obtained relatively simple and straightforward. In particular, the descriptive use of the method is such that it permits experimenters to express compactly and unambiguously the salient features of the observed interaction.
Cancer Risk Assessment Strategies Based on Mechanisms of Action
Authors: Weisburger John H.
Published: November 2007

The induction of cancer by chemicals is a complex process that involves a series of steps, proceeding from the neoplastic conversion of a normal cell, i.e., the discrete mechanistically distinct initiation of a neoplastic cell, through the steps involving promotion, development, and progression. Chemicals can act in each of these stages as initiators, cocarcinogens, promoters, or inhibitors of carcinogenesis. Chemicals must be classified as operating by genotoxic or epigenetic mechanisms. Appropriate short-term in vitro tests used as a battery can be applied to detect such properties. These abbreviated and economic tests have good qualitative decision-making potential, since they are based on mechanisms of action. Advances in molecular biology may provide additional tests to detect cancer risk. Quantitative data available from in vivo dose-response studies demonstrate that carcinogenic effects are dose dependent, and, therefore, a threshold or no-effect level probably exists that is low for potent carcinogens, especially genotoxins, and high for weaker ones, particularly epigenetic agents. A set of mechanism-oriented data must be acquired systematically to serve as basis for realistic and effective risk assessment and management.
USDA's Perspective on Education
Authors: Glosser James W. , York Phyllis B.
Published: November 2007

Our increased knowledge of animals has led to an increased awareness and respect for animal life and a change in our ethical values. The Animal Welfare Act balances the importance and value of animal use and required education for those using animals. This knowledge of animals is just as important as the ability to use modern instrumentation for the validity of research and the future and vigor of the scientific enterprise. Training involves the teaching of skills, whereas education also includes broadening one's knowledge base and changing attitudes. Changing attitudes will be required, and the most effective means of accomplishing this is through human modeling. The United States Department of Agriculture (USDA) will provide a general map of the program but not the details. A certification or registration program for attending veterinarians is being developed with the American Veterinary Medical Association, and a training and reference manual is to be prepared.
Planning a Training Program
Authors: Ewald B. H.
Published: November 2007

The Public Health Service and the USDA now require animal welfare training programs. In planning an animal welfare training program, three questions must be answered: Who? What? and How? An analysis of the groups and individuals required to participate can provide information for eventual course development. The determination of what is to be taught can occur only after an evaluation of existing programs, animal testing activities, and audits. The use of educational objectives can provide the basis for developing a course syllabus.
Training the Toxicologist in Animal Welfare Needs
Authors: Christian Mildred S.
Published: November 2007

Critical factors to be considered when training scientists in regulations, concerns, and methods to ensure humane animal use are the level of education and the social awareness of the individuals. The success of the training is dependent on the awareness and concern of the participating people and the ability of the instructor to address these factors. The scientists (toxicologists) who design, conduct, and evaluate safety studies represent a highly diverse population of individuals whose only common interest may be their governmental, industrial, or academic work group. Reflecting these divergencies in background, experience, and interest, effective training of the toxicologist in animal welfare requirements necessary to his or her work depends on the toxicologist's accepting the need for such education to occur and being given rational reasons for requiring that he or she comply with such regulations. The toxicologist may have concerns regarding animal use that range from guilt to absence of conscious concern. If we recognize that the objective of this training is not only to instruct the toxicologist in the humane use of animals and supply references documenting current requirements but also to convince the toxicologist that this instruction is pertinent to his or her personal goals, such training will be accepted and used.
Animal Alternatives in Toxicology
Authors: Green Sidney
Published: November 2007

Methods using animals have been accepted by toxicologists and other investigators as necessary to provide assurance of safety for environmental agents. The development of alternative approaches to the use of animals focuses on reducing and, in some instances, eliminating the use of animals. It will be easier to develop alternative tests for certain methods in toxicology than for others. The most difficult areas will be those of systemic toxicology, i.e., subchronic and chronic toxicity. There are a number of points that should be considered in the development of alternative tests. Among these are the biological or physiological relevance of the end-point used in the alternative test, where the test fits into a testing scheme, i.e., replacement or as a complement to the animal test, and the necessary quantitative and qualitative validational steps.
Current Problems in Devices Evaluation: Some Solutions
Authors: Wallin Richard F.
Published: November 2007

Medical devices and their component materials are potential sources of toxins that may produce undesirable local or systemic effects when used clinically. Federal regulations thus require manufacturers to establish the safety of their products. Until 1987, FDA provided few specific guidelines for testing medical devices, although many standardized testing methods had been placed in use by industry. Now, proposed guidelines exist, but device manufacturers still face significant problems that are similar to those encountered when testing drugs and chemicals: (1) a strategy for testing must be established to make best use of screening methods, to develop parallel information about various families of products, and to make best use of resources, (2) test articles must be selected to represent finished products, not prototype formulations, (3) sample preparation must be appropriate and relate to product use conditions, (4) test methods that are inappropriate based on end use of a product must be avoided, (5) all potential sources of toxins must be taken into account, including raw materials, processing and manufacturing aids, and sterilization processes, and (6) Good Laboratory Practices must receive appropriate attention. In vitro alternatives to animal test methods are used widely for primary evaluation of biocompatibility, but suitable animal models are not yet available for preclinical evaluation of some devices.
Uses of Toxicology Data for Medical Devices: The FDA Perspective
Authors: West David L.
Published: November 2007

The Tripartite Biocompatibility Guidance for Medical Devices is reviewed, and the toxicity data needed by the Food and Drug Administration to evaluate medical devices is discussed. Some of the types of data required, the rationale for their need, and the legal requirements and processes are emphasized.
Data Requirements for Assessment of Device Risks
Authors: Rodricks Joseph V. , Brown Stephen L.
Published: November 2007

The tools of risk assessment are now applied in the regulation of most classes of commercially produced chemicals, and there appear to be good reasons to apply the technique to potentially hazardous chemical constituents of medical devices. If it is to be applied, several sets of issues and data requirements almost unique to device constituents risk assessment need to be explored. Most important of these are the issues of inter-route extrapolation and assessment of human exposure to device constituents. An example of the latter problem, involving residues of the device sterilant ethylene oxide, is provided to reveal the types of data needed to assess human exposure to device constituents. It also reveals the type of device usage database that has been developed to assist exposure assessment. Several suggestions for dealing with data gaps in all types of device risk assessment are provided.
Origins of Risk Assessment in Food Safety Decision Making
Authors: Rodricks Joseph V.
Published: November 2007

FDA's efforts during the early 1970s to establish acceptable food exposure levels for carcinogenic animal drugs such as diethylstilbestrol (DES) led the agency to incorporate quantitative risk assessment into its decision-making process. During the nearly two decades since FDA first introduced risk assessment as a regulatory tool, its uses have been expanded to almost all areas of chemical regulation. The major driving forces behind this expansion have been (1) the need to deal systematically with the large number of commercially important chemicals that have been identified as animal carcinogens and that have been found to occur widely in the environment and (2) the large number of laws that now require regulatory agencies to establish limits on human exposure to these substances.
Risk Assessment/Risk Management Is a Three-Step Process: In Defense of EPA's Risk Assessment Guidelines
Authors: Goldstein Bernard D.
Published: November 2007

The purpose of this article is to focus on the appropriate use and development of risk assessment and to point out that many of the perceived shortcomings, in fact, represent limitations imposed by the framework in which it is being used and failure to understand the situations for which risk assessment is suited. Risk assessment/risk management is really a three-step not a two-step process. The first step, preceding risk assessment, is science policy, in which the guidelines for the generic performance of risk assessments are established. The benefits of risk assessment to appropriate environmental regulation not only are direct, in terms of improved decision making and priority setting, but also they have the major indirect value of focusing research efforts on crucial uncertainties in a manner that has not been possible in the past.
Life Table Analysis of Carcinogenicity Experiments
Authors: Portier C.J.
Published: November 2007

Recent methods for the analysis of carcinogenicity experiments are summarized and discussed. The discussion centers around survival models aimed at estimating tumor incidence. Practical applications of these models to typical carcinogenicity experiments and to historical control data are discussed. In addition, a simple survival adjustment to the usual trend test in proportions is presented.