RESUMO
OBJECTIVES: The objectives are determine the optimal combination of MR parameters for discriminating tumour within the prostate using linear discriminant analysis (LDA) and to compare model accuracy with that of an experienced radiologist. METHODS: Multiparameter MRIs in 24 patients before prostatectomy were acquired. Tumour outlines from whole-mount histology, T2-defined peripheral zone (PZ), and central gland (CG) were superimposed onto slice-matched parametric maps. T2, Apparent Diffusion Coefficient, initial area under the gadolinium curve, vascular parameters (K(trans),Kep,Ve), and (choline+polyamines+creatine)/citrate were compared between tumour and non-tumour tissues. Receiver operating characteristic (ROC) curves determined sensitivity and specificity at spectroscopic voxel resolution and per lesion, and LDA determined the optimal multiparametric model for identifying tumours. Accuracy was compared with an expert observer. RESULTS: Tumours were significantly different from PZ and CG for all parameters (all p < 0.001). Area under the ROC curve for discriminating tumour from non-tumour was significantly greater (p < 0.001) for the multiparametric model than for individual parameters; at 90 % specificity, sensitivity was 41 % (MRSI voxel resolution) and 59 % per lesion. At this specificity, an expert observer achieved 28 % and 49 % sensitivity, respectively. CONCLUSION: The model was more accurate when parameters from all techniques were included and performed better than an expert observer evaluating these data. KEY POINTS: ⢠The combined model increases diagnostic accuracy in prostate cancer compared with individual parameters ⢠The optimal combined model includes parameters from diffusion, spectroscopy, perfusion, and anatominal MRI ⢠The computed model improves tumour detection compared to an expert viewing parametric maps.
Assuntos
Meios de Contraste , Imageamento por Ressonância Magnética/métodos , Espectroscopia de Ressonância Magnética/métodos , Neoplasias da Próstata/patologia , Idoso , Imagem de Difusão por Ressonância Magnética/métodos , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Próstata/patologia , Curva ROC , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: To validate IMPACT-III (UK), a health-related quality of life (HRQoL) instrument, in British children with inflammatory bowel disease (IBD). PATIENTS AND METHODS: One hundred six children and parents were invited to participate. IMPACT-III (UK) was validated by inspection by health professionals and children to assess face and content validity, factor analysis to determine optimum domain structure, use of Cronbach alpha coefficients to test internal reliability, ANOVA to assess discriminant validity, correlation with the Child Health Questionnaire to assess concurrent validity, and use of intraclass correlation coefficients to assess test-retest reliability. The independent samples t test was used to measure differences between sexes and age groups, and between paper and computerised versions of IMPACT-III (UK). RESULTS: IMPACT-III (UK) had good face and content validity. The most robust factor solution was a 5-domain structure: body image, embarrassment, energy, IBD symptoms, and worries/concerns about IBD, all of which demonstrated good internal reliability (α = 0.74-0.88). Discriminant validity was demonstrated by significant (P â< 0.05, P < 0.01) differences in HRQoL scores between the severe, moderate, and inactive/mild symptom severity groups for the embarrassment scale (63.7 vs 81.0 vs 81.2), IBD symptom scale (45.0 vs 64.2 vs 80.6), and the energy scale (46.4 vs 62.1 vs 77.7). Concurrent validity of IMPACT-III (UK) with comparable domains of the Child Health Questionnaire was confirmed. Test-retest reliability was confirmed with good intraclass correlation coefficients of 0.66 to 0.84. Paper and computer versions of IMPACT-III (UK) collected comparable scores, and there were no differences between the sexes and age groups. CONCLUSIONS: IMPACT-III (UK) appears to be a useful tool to measure HRQoL in British children with IBD.
Assuntos
Ansiedade/psicologia , Doenças Inflamatórias Intestinais/psicologia , Qualidade de Vida/psicologia , População Branca , Adolescente , Ansiedade/epidemiologia , Imagem Corporal , Criança , Análise Fatorial , Feminino , Humanos , Doenças Inflamatórias Intestinais/epidemiologia , Doenças Inflamatórias Intestinais/patologia , Masculino , Inquéritos e Questionários , Reino Unido/epidemiologiaRESUMO
Removal of apoptotic cells is essential for maintenance of tissue homeostasis, organogenesis, remodeling, development, and maintenance of the immune system, protection against neoplasia, and resolution of inflammation. The mechanisms of this removal involve recognition of the apoptotic cell surface and initiation of phagocytic uptake into a variety of cell types. Here we provide evidence that C1q and mannose binding lectin (MBL), a member of the collectin family of proteins, bind to apoptotic cells and stimulate ingestion of these by ligation on the phagocyte surface of the multifunctional protein, calreticulin (also known as the cC1qR), which in turn is bound to the endocytic receptor protein CD91, also known as the alpha-2-macroglobulin receptor. Use of these proteins provides another example of apoptotic cell clearance mediated by pattern recognition molecules of the innate immune system. Ingestion of the apoptotic cells through calreticulin/CD91 stimulation is further shown to involve the process of macropinocytosis, implicated as a primitive and relatively nonselective uptake mechanism for C1q- and MBL-enhanced engulfment of whole, intact apoptotic cells, as well as cell debris and foreign organisms to which these molecules may bind.
Assuntos
Apoptose/imunologia , Proteínas de Ligação ao Cálcio/imunologia , Proteínas de Transporte/imunologia , Complemento C1q/imunologia , Lectinas/imunologia , Macrófagos/imunologia , Pinocitose/imunologia , Receptores Imunológicos/imunologia , Ribonucleoproteínas/imunologia , Calreticulina , Células Cultivadas , Colágeno/imunologia , Colectinas , Humanos , Células Jurkat , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade , Monócitos/citologia , Fagocitose/imunologia , Transdução de Sinais/imunologiaRESUMO
BACKGROUND: The use of minimally invasive ablative therapies in localised prostate cancer offer potential for a middle ground between active surveillance and radical therapy. METHODS: An analysis of men with organ-confined prostate cancer treated with transrectal whole-gland HIFU (Sonablate 500) between 1 February 2005 and 15 May 2007 was carried out in two centres. Outcome data (side-effects using validated patient questionnaires, biochemical, histology) were evaluated. RESULTS: A total of 172 men were treated under general anaesthetic as day-case procedures with 78% discharged a mean 5 h after treatment. Mean follow-up was 346 days (range 135-759 days). Urethral stricture was significantly lower in those with suprapubic catheter compared with urethral catheters (19.4 vs 40.4%, P=0.005). Antibiotics were given to 23.8% of patients for presumed urinary tract infection and the rate of epididymitis was 7.6%. Potency was maintained in 70% by 12 months, whereas mild stress urinary incontinence (no pads) was reported in 7.0% (12 out of 172) with a further 0.6% (1 out of 172) requiring pads. There was no rectal toxicity and no recto-urethral fistulae. In all, 78.3% achieved a PSA nadir < or =0.5 microg ml(-1) at 12 months, with 57.8% achieving < or =0.2 microg ml(-1). Then, 8 out of 13 were retreated with HIFU, one had salvage external beam radiotherapy and four chose active surveillance for small-volume low-risk disease. Overall, there was no evidence of disease (PSA <0.5 microg ml(-1) or negative biopsy if nadir not achieved) after one HIFU session in 92.4% (159 out of 172) of patients. CONCLUSION: HIFU is a minimally invasive, day-case ablative technique that can achieve good biochemical outcomes in the short term with minimal urinary incontinence and acceptable levels of erectile dysfunction. Long-term outcome needs further evaluation and the inception of an international registry for cases treated using HIFU will significantly aid this health technology assessment.
Assuntos
Adenocarcinoma/cirurgia , Neoplasias da Próstata/cirurgia , Ultrassom Focalizado Transretal de Alta Intensidade/métodos , Adenocarcinoma/sangue , Adenocarcinoma/patologia , Idoso , Idoso de 80 Anos ou mais , Biópsia , Intervalo Livre de Doença , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/sangue , Neoplasias da Próstata/patologia , Resultado do Tratamento , Ultrassom Focalizado Transretal de Alta Intensidade/efeitos adversos , Reino Unido , Cateterismo Urinário/efeitos adversosRESUMO
Efficient phagocytosis of apoptotic cells is important for normal tissue development, homeostasis, and the resolution of inflammation. Although many receptors have been implicated in the clearance of apoptotic cells, the roles of these receptors in the engulfment process have not been well defined. We developed a novel system to distinguish between receptors involved in tethering of apoptotic cells versus those inducing their uptake. Our results suggest that regardless of the receptors engaged on the phagocyte, ingestion does not occur in the absence of phosphatidylserine (PS). Further, recognition of PS was found to be dependent on the presence of the PS receptor (PSR). Both PS and anti-PSR antibodies stimulated membrane ruffling, vesicle formation, and "bystander" uptake of cells bound to the surface of the phagocyte. We propose that the phagocytosis of apoptotic cells requires two events: tethering followed by PS-stimulated, PSR-mediated macropinocytosis.
Assuntos
Apoptose/imunologia , Fosfatidilserinas/imunologia , Pinocitose/imunologia , Receptores de Superfície Celular/imunologia , Células 3T3 , Animais , Anticorpos Monoclonais/imunologia , Membrana Celular , Células Cultivadas , Humanos , Histona Desmetilases com o Domínio Jumonji , Camundongos , Monócitos/citologia , Monócitos/imunologia , Fagócitos/imunologia , Proteína cdc42 de Ligação ao GTP/imunologia , Proteínas rac1 de Ligação ao GTP/imunologia , Proteína rhoA de Ligação ao GTP/imunologiaRESUMO
We had previously identified the clock gene D-box binding protein (Dbp) as a potential candidate gene for bipolar disorder and for alcoholism, using a Convergent Functional Genomics (CFG) approach. Here we report that mice with a homozygous deletion of DBP have lower locomotor activity, blunted responses to stimulants, and gain less weight over time. In response to a chronic stress paradigm, these mice exhibit a diametric switch in these phenotypes. DBP knockout mice are also activated by sleep deprivation, similar to bipolar patients, and that activation is prevented by treatment with the mood stabilizer drug valproate. Moreover, these mice show increased alcohol intake following exposure to stress. Microarray studies of brain and blood reveal a pattern of gene expression changes that may explain the observed phenotypes. CFG analysis of the gene expression changes identified a series of novel candidate genes and blood biomarkers for bipolar disorder, alcoholism, and stress reactivity.
Assuntos
Alcoolismo/genética , Transtorno Bipolar/genética , Proteínas de Ligação a DNA/genética , Genoma , Fatores de Transcrição/genética , Alcoolismo/epidemiologia , Animais , Biomarcadores/sangue , Transtorno Bipolar/epidemiologia , Transtorno Bipolar/psicologia , Comorbidade , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Ligação Genética , Humanos , Camundongos , Camundongos Transgênicos , Modelos Genéticos , Fenótipo , Privação do Sono/metabolismo , Estresse Fisiológico/genéticaRESUMO
Progress in understanding the genetic and neurobiological basis of bipolar disorder(s) has come from both human studies and animal model studies. Until recently, the lack of concerted integration between the two approaches has been hindering the pace of discovery, or more exactly, constituted a missed opportunity to accelerate our understanding of this complex and heterogeneous group of disorders. Our group has helped overcome this "lost in translation" barrier by developing an approach called convergent functional genomics (CFG). The approach integrates animal model gene expression data with human genetic linkage/association data, as well as human tissue (postmortem brain, blood) data. This Bayesian strategy for cross-validating findings extracts meaning from large datasets, and prioritizes candidate genes, pathways and mechanisms for subsequent targeted, hypothesis-driven research. The CFG approach may also be particularly useful for identification of blood biomarkers of the illness.
Assuntos
Transtorno Bipolar/genética , Genômica/métodos , Farmacogenética/métodos , Animais , Transtorno Bipolar/tratamento farmacológico , Modelos Animais de Doenças , Marcadores Genéticos/efeitos dos fármacos , Predisposição Genética para Doença/genética , HumanosRESUMO
Anthropometry or human body measurements provide important indicators of nutritional status in children and adults (1). In children, measurements reflect general health status, dietary adequacy, and growth and development over time. In adults, body measurements are used to evaluate health and dietary status, disease risk, and body composition. This report presents anthropometric reference data for 2011-2014 for U.S. children and adults.
Assuntos
Antropometria , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Composição Corporal , Criança , Pré-Escolar , Feminino , Crescimento e Desenvolvimento , Nível de Saúde , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Estado Nutricional , Valores de Referência , Fatores Sexuais , Estados UnidosRESUMO
Hormone response elements (HREs) are considered enhancers, activating transcription in a relatively position- and orientation-independent fashion. Upon binding to an HRE, steroid receptors presumably contact coactivators and/or proteins associated with the transcription initiation complex. As a receptor target site is moved further from a fixed position such as the TATA box, not only will the spatial separation of the receptor with respect to its interaction partners change, so will the orientation due to the rotation of the DNA helix. Additional constraints may be imposed by the assembly of DNA into chromatin. Therefore, we have endeavored to test rigorously the assertion that HRE action is position independent. We have constructed a series of 42 chloramphenicol acetyltransferase expression vectors that contain a single progesterone/glucocorticoid receptor-binding site separated from a TATA box by 4 to 286 bp. The enhancer activity of the HRE was assessed after transient transfection of progesterone receptor-expressing fibroblasts. We find that the position of the HRE has a dramatic influence on induction by progestins. When closely juxtaposed to the TATA box, the HRE was unable to support a hormone response, perhaps due to direct steric hindrance with the transcription initiation complex. Full activity was gained by moving the HRE 10 bp further from the TATA sequence. As the HRE was moved incrementally further, activity remained near maximal over the next 26 bp. HRE activity then declined over the subsequent 26 bp and remained low for another 2.5 helical turns. Surprisingly, a narrow window of HRE activity occurred at an HRE-TATA box separation of 90-100 bp. Little or no hormone-induced transcriptional activity was observed when the HRE was positioned further from the TATA box. The addition of a second HRE or a basal (nuclear factor-1) element failed to relieve this constraint. A similar series of experiments was carried out in a mammary carcinoma cell line that expressed high levels of both glucocorticoid and progestin receptors. Data in these cells indicate that glucocorticoids and progestins supported a similar HRE position-activity profile, but this pattern of HRE activity was quite distinct from that seen in fibroblasts. This may be indicative of cell type-specific interactions between steroid receptors and adapter/coactivator proteins or cell type-specific activities such as acetylases or deacetylases participating in the steroid response.
Assuntos
Dexametasona/farmacologia , Elementos Facilitadores Genéticos , Regulação da Expressão Gênica/efeitos dos fármacos , Congêneres da Progesterona/farmacologia , Promegestona/farmacologia , Receptores de Glucocorticoides/genética , Receptores de Progesterona/genética , Sequência de Bases , Sítios de Ligação , Neoplasias da Mama/patologia , Cloranfenicol O-Acetiltransferase/biossíntese , Cloranfenicol O-Acetiltransferase/genética , Feminino , Fibroblastos , Genes Reporter , Vetores Genéticos/genética , Humanos , Dados de Sequência Molecular , Receptores de Glucocorticoides/biossíntese , Receptores de Progesterona/biossíntese , TATA Box , Transcrição GênicaRESUMO
BACKGROUND: Few studies have assessed how well body mass index (BMI), waist circumference (WC), or waist to height ratio (WtHR) perform in identifying cardio-metabolic risk among youth. OBJECTIVE: The objective of this study was to evaluate the utility of BMI and WC percentiles and WtHR to distinguish adolescents with and without cardio-metabolic risk. METHODS: A cross-sectional analysis of data from 6097 adolescents aged 10-13 years who participated in the HEALTHY study was conducted. Receiver operating characteristic curves determined the discriminatory ability of BMI and WC percentiles and WtHR. RESULTS: The discriminatory ability of BMI percentile was good (area under the curve [AUC] ≥ 0.80) for elevated insulin and clustering of ≥3 risk factors, with optimal cut-points of 96 and 95, respectively. BMI percentile performed poor to fair (AUC = 0.57-0.75) in identifying youth with the majority of individual risk factors examined (elevated glucose, total cholesterol, low-density lipoprotein, blood pressure, triglycerides and high-density lipoprotein). WC percentile and WtHR performed similarly to BMI percentile. CONCLUSIONS: The current definition of obesity among US children performs well at identifying adolescents with elevated insulin and a clustering of ≥3 cardio-metabolic risk factors. Evidence does not support WC percentile or WtHR as superior screening tools compared with BMI percentile for identifying cardio-metabolic risk.
Assuntos
Doenças Cardiovasculares/prevenção & controle , Obesidade Infantil/diagnóstico , Adolescente , Área Sob a Curva , Pressão Sanguínea/fisiologia , Índice de Massa Corporal , Doenças Cardiovasculares/sangue , Criança , Colesterol , Estudos Transversais , Feminino , Humanos , Lipoproteínas HDL , Lipoproteínas LDL , Masculino , Obesidade Infantil/sangue , Obesidade Infantil/prevenção & controle , Curva ROC , Valores de Referência , Medição de Risco , Fatores de Risco , Triglicerídeos/sangue , Circunferência da Cintura , Razão Cintura-EstaturaRESUMO
OBJECTIVES: This report presents the revised growth charts for the United States. It summarizes the history of the 1977 National Center for Health Statistics (NCHS) growth charts, reasons for the revision, data sources and statistical procedures used, and major features of the revised charts. METHODS: Data from five national health examination surveys collected from 1963 to 1994 and five supplementary data sources were combined to establish an analytic growth chart data set. A variety of statistical procedures were used to produce smoothed percentile curves for infants (from birth to 36 months) and older children (from 2 to 20 years), using a two-stage approach. Initial curve smoothing for selected major percentiles was accomplished with various parametric and nonparametric procedures. In the second stage, a normalization procedure was used to generate z-scores that closely match the smoothed percentile curves. RESULTS: The 14 NCHS growth charts were revised and new body mass index-for-age (BMI-for-age) charts were created for boys and girls (http://www.cdc.gov/growthcharts). The growth percentile curves for infants and children are based primarily on national survey data. Use of national data ensures a smooth transition from the charts for infants to those for older children. These data better represent the racial/ethnic diversity and the size and growth patterns of combined breast- and formula-fed infants in the United States. New features include addition of the 3rd and 97th percentiles for all charts and extension of all charts for children and adolescents to age 20 years. CONCLUSION: Created with improved data and statistical curve smoothing procedures, the United States growth charts represent an enhanced instrument to evaluate the size and growth of infants and children.
Assuntos
Desenvolvimento Infantil , Crescimento/fisiologia , Inquéritos Epidemiológicos , Adolescente , Adulto , Antropometria , Centers for Disease Control and Prevention, U.S. , Criança , Pré-Escolar , Humanos , Lactente , National Center for Health Statistics, U.S. , Estados UnidosRESUMO
BACKGROUND: Several different sets of reference body mass index (BMI) values are available to define overweight in children. OBJECTIVE: The objective of this study was to compare the prevalence of overweight in US children calculated with 3 sets of reference BMI values: the revised growth charts of the Centers for Disease Control and Prevention (CDC-US growth charts), international standards proposed by Cole et al, and values developed by Must et al. DESIGN: Data for children and adolescents came from cross-sectional nationally representative US surveys: cycles II and III of the National Health Examination Survey (1963-1965 and 1966-1970) and the first, second, and third National Health and Nutrition Examination Surveys: NHANES I (1971-1974), II (1976-1980), and III (1988-1994). The reference values of Cole et al equivalent to a BMI of 25 were compared with the 85th percentiles from the other 2 methods; the values equivalent to a BMI of 30 were compared with the 95th percentiles. RESULTS: The 3 methods gave similar but not identical results. The reference values of Cole et al gave lower estimates than did the CDC-US growth charts for young children but higher estimates for older children. The reference values of Must et al gave much higher prevalences for younger girls than did the other 2 methods. CONCLUSIONS: Differences between methods were related to differences in data sets, smoothing methods, and theoretical approaches. All 3 methods are based on statistical criteria and incorporate arbitrary assumptions. These methods should be used cautiously, with awareness of the possible limitations.
Assuntos
Índice de Massa Corporal , Obesidade/epidemiologia , Adolescente , Distribuição por Idade , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Inquéritos Nutricionais , Prevalência , Valores de Referência , Distribuição por Sexo , Estados Unidos/epidemiologiaRESUMO
Genomic DNA contamination within RNA samples has important implications for RT-PCR, particularly if there is a pseudogene related to the gene under investigation, because amplification from pseudogenes and reverse-transcribed cDNA can be very difficult to distinguish. Methods to remove DNA contamination cannot guarantee the absolute absence of DNA from the sample without a loss of RNA quantity or quality, which can be crucial for small amounts of RNA or for the investigation of transcripts with a low level of expression. Here, we describe a general technique for RT-PCR that applies a sequence to the 5' tail of reverse-transcribed cDNA that is not present in genomic DNA and uses this for annealing the reverse PCR primer to exclude genomic DNA amplification in unmodified RNA samples.
Assuntos
DNA Complementar/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sequência de Bases , Biotecnologia , Primers do DNA/genética , Feminino , Amplificação de Genes , Gliceraldeído-3-Fosfato Desidrogenases/genética , Humanos , Masculino , Pseudogenes , RNA Neoplásico/genética , RNA Neoplásico/isolamento & purificação , Células Tumorais CultivadasRESUMO
Fourteen patients with unilateral exophthalmos were found on A-scan ultrasound examination to have enlarged extraocular muscles. Thyroid dysfunction later was documented in 12 patients (86%) by laboratory tests and subsequent clinical examination. The suspicion of endocrine orbitopathy was based on the presence of enlarged extraocular muscles in both orbits and on the difference in thickness between corresponding muscles. A-scan orbital examination including specific muscle measurements is a simple and apparently reliable method of diagnosing early thyroid orbitopathy.
Assuntos
Doença de Graves/diagnóstico , Ultrassonografia , Adulto , Idoso , Feminino , Humanos , Hipotireoidismo/diagnóstico , Masculino , Pessoa de Meia-Idade , Músculos Oculomotores/patologia , Nervo Óptico , Órbita , Testes de Função TireóideaRESUMO
Intratracheal thyroid is a rare cause of upper airway obstruction. The obstruction may be true ectopic thyroid tissue or may be caused by invasion of the trachea by a malignant process. We present a case of true ectopic thyroid which illustrates the presentation and management of the condition. The pathogenesis of intratracheal thyroid has been postulated by several authors; here we discuss these rival theories. Because intratracheal thyroid is a rare condition, it may not always be considered early on in case of upper airway obstruction--by presenting this case we hope to remind others of it.
Assuntos
Coristoma/complicações , Sons Respiratórios/etiologia , Glândula Tireoide , Neoplasias da Traqueia/complicações , Adulto , Obstrução das Vias Respiratórias/etiologia , Feminino , HumanosRESUMO
The ultrastructure of H. petricola is described from cultured specimens. Siliceous shell plates are bound by a continuous layer of organic cement which is thicker in the posterior half of the body. The cytoplasm is divided into two distinct portions: anteriorly it is vacuolar and composed of numerous pseudopodial strands; posteriorly it is a compact mass containing the organelles, two or three contractile vacuoles, a typical 'ovular' nucleus with several nucleoli that occupies a central position in a region of dense endoplasmic reticulum, and numerous dictyosomes. Prey is captured by a loose arrangement of pseudopodial strands and digestion occurs within specific areas of compact cytoplasmic strands. It is suggested that the cyst wall of naked amoebae is ruptured by specific enzymatic activity and the contents digested after penetration by cytoplasmic strands. Predated siliceous body plates, enclosed in membrane bound vacuoles are modified by the addition of silica to their surfaces. Some organic particles, like bacteria, may also be coated with biogenic silica. Comparisons are made both with the predation of fungal spores by giant naked amoebae and silica biomineralization in another testate amoeba, Netzelia tuberculata.
RESUMO
Two strains and one population of Difflugia lucida have been studied, from Germany and Japan. The ultrastructure is described from selectively cultured specimens with thin shells; such agglutinate shells have a slightly different morphology from those provided with ample mineral grains. The cytoplasm is described and of particular interest are details of the 'ovular' nucleus, which has an additional lamina to the nuclear membrane, several nucleoli and changes its position within the region of dense endoplasmic reticulum. Two types of organic cement vesicles are secreted by the dictyosomes. The building blocks are spherical in the cytoplasm but when discharged often become elongate strips. Smaller cement vesicles discharge fibrous material which is used either to line the inner shell wall or possibly form the enclosing membrane of cysts. Some cytoplasmic differences associated with the first stage of division and precystic organisation are included. Comparisons are made with recent light microscope observations.
RESUMO
The detailed structure and morphology of the shells of foraminifera and marine testate amoebae found interstitially in littoral sands have been studied by light- and scanning electron microscopy. Species are described within the known taxa. A comparison of shell architecture shows similarities in construction between those shells made from defined plates with those made from agglutinate particles, but lack of biological information prevents suggestions on possible phylogenetic connections. The testacean genus Lagenidiopsis Golemansky, 1974 is transferred to the foraminifera. Empty Tintinnid loricae may possibly be confused with empty testate shells.
RESUMO
A critical examination of the biology and morphology of two species of Cucurbitella, six species of Difflugia and three species of Netzelia is presented. A new term 'necklace' is given to species of Difflugia which have an apertural rim, but lack a distinct collar like those of Cucurbitella. Details of the shell surface composition is used to differentiate some species, and a knowledge of the general biology assists the interpretation of these results. Biometrical data is also shown to be useful in separating morphologically similar species. Cytoplasmic features such as the size and structure of the nucleus and nucleolus is used to further distinguish species. As a consequence of our investigation one new species is erected and several synonyms proposed.
RESUMO
The biology and ultrastructure of Tracheleuglypha dentata is described from studies of specimens grown in clonal culture. Shell formation and cytokinesis appears to be similar to that seen in other members of the family Euglyphidae. The organic cement collar that holds opposed shells together at division is structurally different from that found between shell plates. The status of this collar, which is a transitory structure in field specimens, as a diagnostic feature is discussed. The organic cement that binds shell plates together is divided into three distinct layers. Changes in the cytoplasm and especially the cisternae of the Golgi are described at different stages of reserve shell plate production. Small electron-dense particles seen in the dictyosome are also seen being added to the membrane enclosed vesicles which surround reserve shell plates, this may be evidence to link the Golgi directly with silica deposition.