829 research outputs found

    The Natural History of Ooliths: Franz Ernst Brückmann’s Treatise of 1721 and its Significance for the Understanding of Oolites

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    Franz Brückmann schrieb 1721 seine erste Abhandlung über Oolithe. Wir stellen hier eine Übersetzung des lateinischen Originaltextes ins Englische vor. Brückmann beschreibt die Herkunft des Namens Oolith und seine Synonyme; interpretiert Oolithe als Ansammlung von Fisch-Eiern; klassifiziert sie als Steine; gibt Auftreten und Häufigkeit an; erklärt das Ablagerungsmilieu und Prozesse der Versteinerung und die große Menge der gefundenen Eier; beweist ihre biologische Herkunft und ihre biologischen Beziehungen; unterscheidet die Oolithe von den Pisolithen und gibt Orte an, wo sie gefunden werden. Wir kommentieren Brückmanns Text, besprechen die Wirkung seines Werkes und verfolgen die Forschung über Oolithe bis zum frühen 20. Jahrhundert. Wir schließen, dass Brückmanns Abhandlung am besten als Überblick anzusehen ist, der eine Grundlage für spätere Forschungen bildete. Sein wichtigster Beitrag war, Oolithe eher als Anhäufungen von biologischen Überresten als „Spiele der Natur“ (lusus naturae) anzusehen. Einige von Brückmanns Zeitgenossen, wie Da Costa und De Saussure zweifelten, dass Fischeier versteinern könnenund – obgleich sie die biologische Herkunft einräumten – zogen es vor, sie als mineralische Konkretionen zu betrachten. Große Neuerungen in der Stratigraphie, Paläontologie, Mikrobiologie, Mikroskopie, vergleichenden Sedimentologie und Petrologie mußten stattfinden, bevor im 19. Jahrhundert signifikante Fortschritte von Brückmanns Interpretationen gemacht werden konnten.Franz Brückmann wrote his treatise on oolites in 1721. We present here an English translation of his Latin text which describes the following topics; derivation of the name “oolith” and its synonyms; interpretation as accumulations of fish-eggs; classification as stones; occurrence and diversity; environments of deposition and processes of lithification; explanations for the large quantities of eggs found; evidence for their biological origin; evidence for their biological associations; the distinction between ooliths and pisoliths; and localities of occurrence. We provide a commentary on Brückmann’s text, and then review the impact of his work by tracing the subsequent development of research on Oolites up to the early twentieth century. We conclude that Brückmann’s treatise is best regarded as a review paper that provided a platform for later research. His most significant contribution was to view oolites as accumulations of petrified biological remains rather than as “sports of nature”. Some of Brückmann’s near contemporaries such as Da Costa and De Saussure doubted that fish eggs could lithify and, although conceding their sedimentary origin, preferred to regard them as mineral concretions. Major developments in the sciences of stratigraphy, palaeontology, microbiology, microscopy, comparative sedimentology, and petrology would be required before more significant advances could be made on Brückmann’s interpretations

    The effect of developmental vitamin D deficiency in male and female Sprague-Dawley rats on decision-making using a rodent gambling task

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    Developmental vitamin D (DVD) deficiency is a plausible risk factor for schizophrenia that has been associated with behavioural alterations including disruptions in latent inhibition and response inhibition. The rodent gambling task (rGT) assesses risk-based decision-making, which is a key cognitive deficit observed in schizophrenia patients. The primary aim of this study was to examine risk-based decision-making in DVD-deficient and control rats on the rGT. We also evaluated the performance of female Sprague–Dawley rats on the rGT for the first time. Adult male and female Sprague–Dawley rats from control and vitamin D deficient dams were trained to perform the rGT in standard operant chambers and their performance and choice-preferences were assessed. Female rats were significantly faster to reach rGT training criteria compared with male rats and DVD-deficient rats were faster to reach training criteria than control animals. After reaching stable performance on the rGT DVD-deficient and control rats showed a significant preference for the optimal choice-option in the rGT, but there were no significant effects of sex or diet on these responses. DVD deficiency did not alter the decision-making processes on the rGT because no significant changes in choice-preferences were evident. This is the first study to demonstrate that once established, the performance of females is comparable to male Sprague–Dawley rats on the rGT

    New Perspectives on Rodent Models of Advanced Paternal Age: Relevance to Autism

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    Offspring of older fathers have an increased risk of various adverse health outcomes, including autism and schizophrenia. With respect to biological mechanisms for this association, there are many more germline cell divisions in the life history of a sperm relative to that of an oocyte. This leads to more opportunities for copy error mutations in germ cells from older fathers. Evidence also suggests that epigenetic patterning in the sperm from older men is altered. Rodent models provide an experimental platform to examine the association between paternal age and brain development. Several rodent models of advanced paternal age (APA) have been published with relevance to intermediate phenotypes related to autism. All four published APA models vary in key features creating a lack of consistency with respect to behavioral phenotypes. A consideration of common phenotypes that emerge from these APA-related mouse models may be informative in the exploration of the molecular and neurobiological correlates of APA

    Developmentally vitamin D-deficient rats show enhanced prepulse inhibition after acute δ9-tetrahydrocannabinol

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    Developmental vitamin D (DVD) deficiency has been proposed as a risk factor for schizophrenia. DVD-deficient rats show selective cognitive deficits and novelty-induced hyperlocomotion and enhanced locomotor responses from acute treatment with psychomimetic drugs, such as amphetamine and MK-801. Here we aimed to examine the effect of a drug from a different class of psychomimetic/psychoactive compounds, Δ-tetrahydrocannabinol (THC), on tasks of relevance to the cognitive and positive symptoms of schizophrenia. The aim of this study was to investigate whether DVD deficiency modulates the behavioural effects of THC on tests of delay-dependent memory, sensorimotor gating and locomotion. Adult control and DVD-deficient rats were injected with THC (0, 0.3, 0.6, 1.25, 2.5 mg/kg) 15 min before a delay match to sample (DMTS) task using variable delays (0-24 s). A separate group of rats was injected with either 2.5 mg/kg THC or vehicle before tests of either prepulse inhibition (PPI) of the acoustic startle response or in the open field. Control and DVD-deficient rats showed a similar dose-dependent impairment in performance on the DMTS. The greatest impairment was observed at 2.5 mg/kg for all delays (0-24 s). DVD-deficient rats showed THC-induced enhancement of PPI, which was not observed in control rats. There was no effect of maternal diet on acoustic startle response or locomotor responses in the open field. This study reports the novel findings that DVD-deficient rats were more sensitive to the acute effects of THC on PPI. It appears that prenatal vitamin D deficiency has long-term effects on sensitivity to the behavioural effects of cannabinoids

    The developmental vitamin D (DVD) model of schizophrenia

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    It is now widely acknowledged that exposure to adverse environmental factors in utero may not only affect how the brain develops but have long-lasting consequences for later brain function in the adult offspring. This idea has gained particular prominence amongst researchers interested in the etiology of neurodevelopmental disorders such as schizophrenia and autism. Approximately 10 years ago we proposed that developmental vitamin D (DVD) deficiency may explain several epidemiological features of this disease, most noticeably the winter/spring season of birth effect. In 2003 we published results from our first study indicating there were structural changes in how the brain develops in these offspring. Since then we have firmly established that DVD deficiency not only affects brain cell differentiation and gross anatomy but also produces alterations in behavior in these offspring as adults. In this chapter we describe how we came to construct the model we use today. Over the past 7 years the model has proved informative producing both structural brain changes (ventriculomegaly) and behavioral alterations (hyperlocomotion in response to NMDA antagonists) that are thought to be relevant to schizophrenia

    Is there an association between metabolic syndrome and rotator cuff related shoulder pain? A systematic review

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    Objectives Rotator cuff related shoulder pain (RCRSP) is a common upper limb complaint. It has been suggested that this condition is more common among people with cardiometabolic risk factors. This systematic review has synthesised evidence from case-control, cross-sectional and cohort studies on the association between metabolic syndrome (MetS) and RCRSP. Design and Data Sources Five medical databases (MEDLINE, EMBASE, SCOPUS, CINAHL and AMED) and reference checking methods were used to identify all relevant English articles that considered MetS and RCRSP. Studies were appraised using the Newcastle Ottawa Scale (NOS). Two reviewers performed critical appraisal and data extraction. Narrative synthesis was performed via content analysis of statistically significant associations . Results Three cross-sectional, two case-control and one cohort study met the inclusion criteria, providing a total of 1,187 individuals with RCRSP. Heterogeneity in methodology and RCRSP or MetS definition precluded a meaningful meta-analysis. Four of the included studies identified associations between the prevalence of MetS and RCRSP. Studies consistently identified independent cardiometabolic risk factors associated with RCRSP. All studies were level III evidence. Summary and Conclusion The low-moderate quality evidence included in this review suggests an association between MetS and RCRSP. Most studies demonstrated moderate quality on appraisal. The direction of association and cardiometabolic factors influencing should be investigated by longitudinal and treatment studies. These preliminary conclusions and clinical utility should be treated with caution due to limitations of the evidence bas

    Genetic Analysis of the Functions and Interactions of Components of the LevQRST Signal Transduction Complex of Streptococcus mutans

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    Transcription of the genes for a fructan hydrolase (fruA) and a fructose/mannose sugar:phosphotransferase permease (levDEFG) in Streptococcus mutans is activated by a four-component regulatory system consisting of a histidine kinase (LevS), a response regulator (LevR) and two carbohydrate-binding proteins (LevQT). The expression of the fruA and levD operons was at baseline in a levQ mutant and substantially decreased in a levT null mutant, with lower expression with the cognate inducers fructose or mannose, but slightly higher expression in glucose or galactose. A strain expressing levQ with two point mutations (E170A/F292S) did not require inducers to activate gene expression and displayed altered levD expression when growing on various carbohydrates, including cellobiose. Linker-scanning (LS) mutagenesis was used to generate three libraries of mutants of levQ, levS and levT that displayed various levels of altered substrate specificity and of fruA/levD gene expression. The data support that LevQ and LevT are intimately involved in the sensing of carbohydrate signals, and that LevQ appears to be required for the integrity of the signal transduction complex, apparently by interacting with the sensor kinase LevS

    Cognitive performance and response inhibition in developmentally vitamin D (DVD)-deficient rats

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    Evidence from epidemiological studies suggest that low levels of vitamin D during early life alter brain development and may increase the risk of various adverse health outcomes, including schizophrenia. The aim of this experiment was to examine the effect of developmental vitamin D (DVD) deficiency on attentional processing using the 5-choice serial reaction time task (5C-SRT) and the 5-choice continuous performance test (5C-CPT), which specifically assesses sustained attention and vigilance in rodents. DVD-deficient and control rats were exposed to a series of target and non-target trials within each operant testing session. A number of measures were recorded including hit, miss, false alarm and correct rejection, as well as premature and perseverative responses. Performance on 5C-CPT was also assessed after administration of the atypical antipsychotic, clozapine. The adult offspring of DVD-deficient rats had higher levels of impulsivity, as demonstrated by a significant increase in premature responses. On the 5C-SRT and target trials of the 5C-CPT, accuracy was not significantly affected by prenatal diet; however DVD-deficient rats made 50% fewer correct rejections compared to controls on non-target trials of the 5C-CPT. Thus, control rats were able to discriminate between target and non-target trials, whereas DVD-deficient rats were unable to make this discrimination. Clozapine reduced the occurrence of false alarms in DVD-deficient rats to a level comparable to control values. Taken together these data suggest DVD-deficient rats have increased impulsivity as well as a lack of inhibitory control, and these features may be informative in terms of modeling the cognitive deficits observed in schizophrenia

    The neurodevelopmental hypothesis of schizophrenia: Convergent clues from epidemiology and neuropathology

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    The neurodevelopmental hypothesis of schizophrenia suggests that the disruption of early brain development increases the risk of later developing schizophrenia. This hypothesis focuses attention on critical periods of early brain development. From an epidemiologic perspective, various prenatal and perinatal risk factors have been linked to schizophrenia, including exposures related to infection, nutrition, and obstetric complications. From a genetic perspective, candidate genes have also been linked to altered brain development. In recent decades evidence from neuropathology has provided support for the neurodevelopmental hypothesis. Animal models involving early life exposures have been linked to changes in these same brain systems, providing convergent evidence for this long-standing hypothesis
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