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PubMed1984

Reproduction and sexual development in a freshwater gastrotrich. 3. Postparthenogenic development of primary oocytes and the X-body.

Six small cells are present in each of the bilateral gonads of parthenogenically reproductive Lepidodermella squammata. Early in the extended postparthenogenic phase of the life history, these cells undergo limited proliferation followed by differentiation. Primary oocytes of three types are present 0.3 days after deposition of the final parthenogenic egg: small oocytes with presynaptic nuclei; intermediate oocytes with nuclei containing synaptonemal complexes; and larger oocytes with a germinal vesicle. Oocytes persist without further development at least until day four of the postparthenogenic phase. Older isolated animals may contain and even deposit an enlarged egg, but successful progeny does not result. Oocytes are located at the anterior pole of each of the bilateral gonads, adjacent to developing male tissues producing sperm. More posterior cells in the gonad are initially undifferentiated in the postparthenogenic phase. Dorsal and central cells first show specialization for secretory activity, and by day four contain peripheral layers of RER and central accumulations of polymorphic secretion droplets. The posterior and ventral cells produce secretion droplets that aggregate into an enlarging bilobed structure called the X-body. Two or three cells in each gonad contribute secretions to the X-body, which is intracellular in a secondary syncytium formed by the contributing cells. Functions for the postparthenogenic gametes and for the X-body are not yet demonstrated.

Animals↗

PubMed1977

Three-dimensional development of luminal projections and junctional complexes in the developing central nervous system blood vessels of the rat.

The luminal surface features and junctional complexes from developing blood vessels in the rat central nervous system have been studied by high-voltage electron microscopy and scanning electron microscopy. Developing blood vessels exhibit three types of luminal projections; marginal folds or ridges at junctional complexes, ridges not at junctional complexes and microvilli. Both types of ridges are associated with troughs or depressions in the luminal surface of the endothelial cell. Those ridges not associated with junctional complexes take part inthe production of enclosed tunnels in the endothelial cell cytoplasm. Fusion of the external leaflets of junctional complexes between adjacent endothelial cells occurred, initially, near the luminal surface of the blood vemina secondarily. Further fusion activity to produce the zonula occludens type junction appeared to spread outwards from the smaller fusion sites.

Animals↗

PubMed1987

Isomyosin expression in developing chicken atria: a marker for the development of conductive tissue?

Isomyosin expression patterns in embryonic chicken atria during the first two weeks of development were analyzed immunohistochemically. In the 3-days embryonic chicken heart (HH19-20), strong coexpression of both isomyosins can be found as band-like zones at the lateral sides of the sinoatrial junction. The zones converge on the bottom of the atrium and continue as a band around the atrioventricular canal. In the 5-days heart (HH27-28) the coexpression area encompasses the entire sinoatrial junction and extends into parts of the sinus venosus and into the dorsocaudal atrial wall. In the 7-days heart (HH 32-33) the relative extension of coexpression areas reaches its maximum. Coexpression is also found in a ring-like band in the ventral (bottom) wall of the atria peripheral to the ring-like band in the atrioventricular junction. The latter band has now become continuous with the coexpression area in the bottom of the interatrial septum. Caudally coexpression extends behind the atrioventricular cushions towards the interventricular septum and cranially coexpression of the atrioventricular junction has become continuous with that of the ring around the outflow tract (cf Sanders et al. 1986). In the second week of incubation a decrease of coexpression is observed. The isomyosin expression pattern described in this study has put forward additional arguments that the conductive tissue originates from areas that continue to express both isomyosins relatively late in development.

Animals↗

PubMed1978

On the development of the cerebellum of the trout, Salmo gairdneri. IV. Development of the pattern of connectivity.

Synaptogenesis has been studied in the corpus cerebelli of the trout Salmo gairdneri, Richardson, 1836. The first synapses are observed in hatchlings and occur between parallel fibres and the shafts of Purkinje dendrites. Subsequently the axosomatic synapses of Purkinje axon collaterals on the neurons of the ganglionic layer appear, and finally the synapses made by climbing fibres and mossy fibres, and by stellate cell axons develop. Young synapses in the cerebellum of the trout resemble the mature structures so closely that the criteria for the identification of the latter can also be applied to the former. The number of parallel fibre synapses and of Purkinje axon collateral synapses increases considerably during development. Eurydendroid cells, the axons of which leave the cerebellum, receive an abundance of Purkinje axon collaterals on their somata and main dendritic trunks. Mossy fibre synapses are numerous in the granular layer. Climbing fibre contacts and synapses of stellate cell axons, both with Purkinje cells, are found occasionally. The following pattern of connectivity is proposed. The main input-output system is formed by the mossy fibres, the granule cells, the Purkinje cells and the eurydendroid cells. Additional pathways are formed by (1) the mossy fibres, granule cells and eurydendroid cells, and (2) the climbing fibres, Purkinje cells and eurydendroid cells. The afferent-efferent systems, mentioned above, are influenced by a number of internuncial elements: (1) The Golgi cells receive their input from the parallel fibres and contact with their axon collaterals the dendrites of granule cells. (2) Axon collaterals of Purkinje cells are in synaptic relation with Golgi cells. (3) Axon collaterals of Purkinje cells impinge upon the somata and main dendrites of other Purkinje cells. (4) Stellate cells, which derive their input from the parallel fibres, synapse with dendrites and somata of Purkinje cells. The possible functional roles of all of these neuronal elements are discussed.

Animals↗

PubMed1987

Postnatal development of immunohistochemically localized spectrin-like protein (calspectin or fodrin) in the rat visual cortex: its excessive expression in developing cortical neurons.

Postnatal development of the expression and localization of a membrane-associated cytoskeletal protein, calspectin (fodrin or brain spectrin), in the visual cortex, was immunohistochemically studied in newborn to adult rats, by using an anti-calspectin antibody. At birth, calspectin-immunoreactivity was already present at the plasma membrane and in the cytoplasm of neurons which were mostly pyramidal cells located in the upper part of the cortical subplate. Immature neurons located in the cortical plate were not stained by the antibody, suggesting that calspectin is expressed only in neurons which have differentiated or are differentiating. At postnatal days 2 to 7, immunoreactive neurons were dramatically increased in layers V and VI and very intense labelling was seen in the apical dendrites of layer V pyramidal cells. Most of the stained processes of these and other neurons showed signs of rapid dendritic growth, i.e. non-terminal as well as terminal growth cones and filopodia. At days 10 to 17, dendrites of pyramidal cells in layers II and III became clearly detectable, although still slender. At days 24 to 34, the basal dendrites of pyramidal cells in layers II, III and V became intensely immunoreactive and dendritic spines were visualized by the antibody. In the adult, however, the calspectin immunoreactivity became very weak and spines were not recognizable. At all the ages, axons and neuroglia were unstained. Also, most of the neurons in layer IV of the cortex were not immunoreactive. These results suggest that calspectin is most abundantly expressed in growing parts of the dendrites and spines. A hypothesis that calspectin may play a role in synaptic plasticity in the developing visual cortex is discussed.

Aging↗

PubMed1988

Development of macroglial cells in rat cerebellum. I. Use of antibodies to follow early in vivo development and migration of oligodendrocytes.

The origin of oligodendrocytes and astrocytes in the CNS is still a focus of much experimentation and controversy. We have used antibodies against ganglioside GD3 and galactocerebroside (GC) to follow the origin and development of rat cerebellar oligodendrocytes both in vitro and in vivo. The immunofluorescent identification of GC+ cells in the rat neonatal cerebellum in vivo, revealed that cells initially GD3+/GC- appeared to make the transition via GD3+/GC+ cells to GD3-/GC+ oligodendrocytes. This sequence of events closely paralleled the maturation of cerebellar oligodendrocyte precursors found in serum-free dissociated culture. In contrast, whereas both GD3+ and glial fibrillary acidic protein-positive cells were seen in serum-containing dissociated culture and also in freshly dissociated suspensions of cerebellum at postnatal days 0 to 6, such cells could not be identified in situ. Putative GD3+/GC- oligodendrocyte precursor cells arose from the deeper regions of the cerebellum at birth, perhaps initially from the superior medullary velum adjacent to the fourth ventricle, and appeared to migrate into the developing folia just prior to myelination and the acquisition of GC.

Animals↗

PubMed2006

Expression of AmphiPOU-IV in the developing neural tube and epidermal sensory neural precursors in amphioxus supports a conserved role of class IV POU genes in the sensory cells development.

POU genes play a prominent role in the nervous system differentiation of several organism models, and in particular, they are involved in the differentiation of sensory neurons in numerous invertebrate and vertebrate species. In the present report, cloning and expression profile of a class IV POU gene in amphioxus was assessed for understanding its role in the sensory systems development. A single class IV gene, AmphiPOU-IV was isolated from the amphioxus Branchiostoma floridae. From a phylogenetic point of view, AmphiPOU-IV appears to be strictly related to the vertebrate one, sharing a high homology ratio especially with all vertebrate POU-IV proteins Brn-3a, Brn-3b, and Brn-3c. AmphiPOU-IV was found in the most anterior neural plate and in scattered ectodermic cells on the flanks of neurula, such ectodermic cells resemble the characteristic morphology and position of AmphiCoe and AmphiTrk developing sensory cells. Later on, the expression was confined in some motoneurons at level of the PMC and in some segmental arranged motoneurons in the hindbrain. Such expression is also maintained in larvae, and a new site of AmphiPOU-IV expression was also found in rostrum and mouth edge epidermal sensory cells of the larva. In conclusion, our data suggest an evolutionary conserved role of POU-IV transcription factors in the specification and differentiation of the sensory system in both vertebrates and invertebrates and underline the importance of amphioxus as linking step between them.

Amino Acid Sequence↗

PubMed2005

Embryological study of the development of the rat temporomandibular joint: highlighting the development of the glenoid fossa.

Basic embryological findings on the development of the temporomandibular joint have yet to be elucidated sufficiently. This experiment, was undertaken to find the standard time course of the development of the temporomandibular joint in rat fetuses. Serial frontal and sagittal sections of rat fetal heads (between 13.5 and 20.5 days post-conception [p.c.]) were examined microscopically. The condyle was recognized as a mesenchymal condensation at 14.5 days p.c., while the glenoid fossa was recognized at 15.5 days p.c. The mesenchymal condensation of the condyle had differentiated into chondrocytes by 16.5 days p.c., and endochondral ossification was recognized at 17.5 days p.c. The intramembranous ossification of the glenoid fossa was already recognized by 16.5 days p.c.; this started in the posterior region and progressed anteriorly between the zygomatic arch and the squamous part of the temporal bone. Ossification of the condyle had not been completed by 20.5 days p.c., a mass of hypertrophic chondrocytes remained in the center of the condylar head. The glenoid fossa was almost completely ossified by 19.5 days p.c. A coarse region of cells, reminiscent of apoptosis, was recognized in the region of the prospective superior joint space at 17.5 days p.c., and an actual joint space had formed by 18.5 days p.c. The inferior joint space was recognized at 19.5 days p.c. as a fissural cavity, but it was much narrower than its superior counterpart. The prospective meniscus was distinguished on the condylar surface at 17.5 days p.c. by the difference in the shape of its constituent cells. The results obtained here seem to be useful for further experiments and molecular biological studies.

Animals↗

PubMed2005

Non-linear mixed effects modeling - from methodology and software development to driving implementation in drug development science.

Few scientific contributions have made significant impact unless there was a champion who had the vision to see the potential for its use in seemingly disparate areas-and who then drove active implementation. In this paper, we present a historical summary of the development of non-linear mixed effects (NLME) modeling up to the more recent extensions of this statistical methodology. The paper places strong emphasis on the pivotal role played by Lewis B. Sheiner (1940-2004), who used this statistical methodology to elucidate solutions to real problems identified in clinical practice and in medical research and on how he drove implementation of the proposed solutions. A succinct overview of the evolution of the NLME modeling methodology is presented as well as ideas on how its expansion helped to provide guidance for a more scientific view of (model-based) drug development that reduces empiricism in favor of critical quantitative thinking and decision making.

Algorithms↗

PubMed1992

Procedure for development of an enzyme-linked immunosorbent assay. Development of an assay for human apolipoprotein A-I.

A set of criteria for selection of antibodies during the development of enzyme-linked immunosorbent assay (ELISA) is described. Using these criteria, a competitive ELISA for human apo A-I using a polyclonal goat antibody was developed. The assay recognizes apo A-I from plasma and high-density lipoprotein (HDL), as well as the pure delipidated apo A-I, equally. Intra- and inter-assay variations were 5.2% and 3.5%, respectively. Recovery rate, as determined by spiking a known quantity of pure delipidated apo A-I into a reference plasma, was determined to be 101.3%. The assay was validated by comparing the concentration of apo A-I in HDL with the dye elution method. The apo A-I ELISA to apo A-I dye elution ratio was 1.01. Apo A-I concentration in Centers for Disease Control reference material determined by this method was in agreement with the reported consensus value. Repeated freezing and thawing of the samples (three freeze-thaw cycles at -20 degrees C) as well as long-term freezing (up to 1 year at -70 degrees C) did not affect the concentration of apo A-I in the samples. The assay was applicable both to normolipidemic and dyslipidemic plasmas. No immunologic difference was noted when plasma from dyslipidemic subjects was assayed. A frequent problem of long-term storage is deamidation. The values found for apo A-I in a deamidated plasma were the same as those for the corresponding fresh plasma. Plasma apo A-I values were also positively correlated with that of HDL-cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗

PubMed1988

Observations on the development of certain ascending inputs to the thalamus in rats. I. Postnatal development.

We have studied the postnatal development of the major ascending afferents to the thalamus in postnatal rats using tetramethylbenzidine histochemistry following wheat germ agglutinin-conjugated horseradish peroxidase injections into either the dorsal column nuclei, the deep cerebellar nuclei, or the inferior colliculus. By the day of birth, the efferents from each of these regions have already entered, and arborized extensively within, their appropriate thalamic relay nuclei. However, the overall distribution of each of these ascending afferent systems differs dramatically from that seen in mature rats. In neonatal rats, a substantial proportion of the ascending axons extend beyond the thalamus and often enter the internal capsule, some bypassing the thalamus altogether. In addition, some of the axons which enter and arborize within the thalamus extend beyond their appropriate terminal field into adjoining thalamic nuclei. Retrograde tracing experiments utilizing Fast blue indicate that the cells of origin of these overshooting axons are distributed similarly to the cells of origin of the definitive thalamic afferents. These early erroneous projections are all subsequently eliminated and the characteristically restricted adult distribution of each afferent system is evident by P30. These results indicate that developmental overgrowths and targeting errors of thalamic afferent fibers are not unique to the visual system (where they have been documented previously), but may be a general feature in the development of these pathways.

Afferent Pathways↗

PubMed1992

Transition from developing to mature patterns of acetylcholinesterase activity in rat visual cortex: implications for the time-course of geniculocortical development.

Patterns of acetylcholinesterase (AChE) histochemical staining in cortical area 17 differ in infant and mature rats. In infants, intense AChE activity is seen as a band corresponding to layer IV and deep layer III of the visual cortex, and this staining is associated with terminal fields of geniculocortical neurons. In adult animals, AChE activity is densest in deep layer IV and layer V and is associated with projections originating in the basal forebrain. The present study investigated the transition from developing to mature patterns of AChE staining in visual cortex. Unilateral lesions were placed in either the lateral geniculate body or the basal forebrain of rats postnatal days 8 (P8) to adulthood; the effects of these lesions on patterns of AChE activity in visual cortex were studied with histochemical techniques and optical densitometry. Lesions involving the lateral geniculate body markedly reduce AChE activity in visual cortex of P12 rats, had moderate effects in P20 rats, and had no apparent effect on AChE activity of visual cortex of rats aged P40 and older. Lesions of basal forebrain had little effect on AChE activity in visual cortex of P12 animals, increasing effect in P15-35 rats, and eliminated much of AChE staining in visual cortex of adults. The period of transition from developing to mature patterns of AChE activity in visual cortex of animals bilaterally enucleated at birth was not different from the period of transition in normally sighted animals. These data indicate that mature patterns of AChE activity in visual cortex are not achieved until well into the second month of life. If transient AChE expression is characteristic of geniculocortical neurons during the period of time in which axons are proliferating within visual cortex, then these data indicate that geniculocortical connections may be forming well into the second month of life in the rat.

Acetylcholinesterase↗

PubMed1995

Developing interactive computer-based simulations: an object-oriented development methodology enhances computer-assisted instruction.

The purpose of this research was to investigate the application of object-oriented technology and AI techniques to enhance development of computer-based training simulations. Towards that end, a comprehensive computer-assisted instructional unit was developed to teach the skills and concepts of window-based applications, the OS/2 desktop, and the use of a patient care information system. By taking advantage of sophisticated computer graphics for the visual representation of objects and the behavioral modeling capabilities of the object-oriented language, domain knowledge modeling and human-computer interactions were implemented without complex natural language processing techniques. The results of this research indicate that nurses and physicians are able to learn the basic skills and concepts of computer systems and how to query for patient information. The new methodology described for building these computer-assisted instructional simulations significantly eased the training and teaching of large numbers of nurses and physicians and simplified their transition to a complex, computer-based hospital information system environment.

Computer Graphics↗

PubMed1980

The critical role of the nucleolus in cell differentiation and stem cell development with particular reference to its importance in imaginal development, spermatogenesis and haemopoiesis - a new fundamental concept.

A new approach to cell staining and cell culture is used which allows for better observation of nucleolar behaviour than is possible with traditional methods. The role of the nucleolus in stem cell maturation in the mosquito and woodlouse is discussed, and evidence presented to show that certain of their stem cells are multi-nucleolated cells and that they give rise to a clone of small round cells (daughter cells) by a novel method of division. This type of cell formation has been given the name "clonal division" to distinguish it from classical mitotic division. The new approach is used in the search for the elusive haemopoietic stem cell and evidence presented to show that this is also a multinucleolated stem cell which, in like fashion, gives rise to a clone of small round cells. The development takes place extravascularly, and the small round cells which arise are the immediate precursors of the differentiated cells found in peripheral blood. An analysis of the role of the nucleolus in stem cell development is made, and the conclusion reached that it plays an important part in clonal division, its behavior being consistent with some form of instructional role. It is suggested that all primitive cells are enveloped in a basophilic reticulum which is composed of instructional RNA responsible for the transformation of the primitive cell into a differentiated cell. It is further suggested that the nucleoli and basophilic reticulum are but interchangeable forms of the one structure (to be known as nucleolar material), and that this is inherited the same way that chromosomal material is inherited.

Animals↗

PubMed1981

The effect of lentinan on the in utero foetal development of the rat and on postnatal development of the F1 offspring.

Lentinan, a polysaccharide [(1 leads to 3)-beta-D-glucan], at 0.1, 1.0 and 5.0 mg/kg/day was administered i.v. to rats once daily from day 15 of pregnancy to day 21 post partum. All animals were allowed to deliver their young and selected animals of the F1 generation were retained without further treatment, to provide F2 offspring. Reactions to treatment were generally dose-related and included bruising of the tail and swelling and discolouration of the pinnae. Animals at 5.0 mg/kg/day sometimes showed swollen hind limbs and cutaneous lesions of the tail. Mean spleen weight in females was increased at all dosages, more so at 1.0 and 5.0 mg/kg/day. There was no evidence of an adverse effect on litter characteristics, including the pre-weaning development of the F1 offspring, or that treatment of the F0 parents adversely affected post-weaning development and reproductive performance of the F1 offspring.

Abnormalities, Drug-Induced↗

PubMed2005

GPI-specific phospholipase D (GPI-PLD) is expressed during mouse development and is localized to the extracellular matrix of the developing mouse skeleton.

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is abundant in serum and has a well-characterized biochemistry; however, its physiological role is completely unknown. Previous investigations into GPI-PLD have focused on the adult animal or on in vitro systems and a putative role in development has been neither proposed nor investigated. We describe the first evidence of GPI-PLD expression during mouse embryonic ossification. GPI-PLD expression was detected predominantly at sites of skeletal development, increasing during the course of gestation. GPI-PLD was observed during both intramembraneous and endochondral ossification and localized predominantly to the extracellular matrix of chondrocytes and to primary trabeculae of the skeleton. In addition, the mouse chondrocyte cell line ATDC5 expressed GPI-PLD after experimental induction of differentiation. These results implicate GPI-PLD in the process of bone formation during mouse embryogenesis.

Animals↗

PubMed2006

Development of competency inventory for registered nurses in the People's Republic of China: scale development.

BACKGROUND: Literature review indicated there is no existing nursing competency framework or instrument for Chinese registered nurses. By virtue of its global leadership role in nursing, the International Council of Nurses (ICN) developed an ICN Framework of Competencies for the Generalist Nurses in 2003. On the basis of the ICN's framework, a qualitative study was conducted to explore the expectations of Chinese nurse professionals on nursing competency in the previous study. A competency framework for Chinese registered nurses was formed. This paper describes the development and testing of the Competency Inventory for Registered Nurses (CIRN). METHODS: A methodological study design was used, consisting of two phases with six steps. A review of literature generated 112 items, which were evaluated by six experts followed by field testing in a purposive sample of 815 Chinese clinical registered nurses. Factor analysis and item analysis were applied to establish the scale's construct validity and reliability. RESULTS: The final scale consists of seven dimensions with 58 items. The overall scale reliability had a Cronbach's alpha of 0.89; the dimensions Cronbach's alpha ranged from 0.79 to 0.86. In addition, evidence for two other kinds of validity was obtained, which included criterion-related validity (r=0.44, p=0.04) and contrasted-group validity (p<0.001). CONCLUSION: The CIRN has demonstrated evidence of internal consistency reliability, content validity, and construct validity, and it provides an objective tool for assessing registered nurse competencies in the various areas of clinical practice.

Adult↗

PubMed2006

Impacts of a participatory approach to developing national level sustainable development indicators in Finland.

The paper explores the role of a participatory approach in the outcome of the Finnish sustainable development indicator (SDI) exercise in 1998-2002. The process is analysed through three main objectives: to achieve stronger democracy, better quality of the end product and a more effective process. The analysis is further structured by a set of criteria needed for successful participation and differentiation of types of participants. The criteria comprise three main aspects: fairness, competence and social learning. In addition to the normally mentioned stakeholders (e.g. citizens and interest groups) participants also include experts and civil servants. Using the set of criteria above the participatory approach of the Finnish SDI process is then evaluated, and in the light of this evaluation the paper also discusses the specifications needed as evaluation criteria for national level policy programme processes like developing the SDIs. The results are based on documentation of the indicator task force meetings, written comments and a study of the putative end-users conducted after the publication of the indicators. The results show that the intense and broad participation of experts and civil servants increased the competence of the outcome and led to greater efficiency in working methods. However, this led to technocratic participation, absence of democratic participation and absence of social learning. Thus the ultimate goal of SDIs to contribute to achieving sustainability was not reached.

Conservation of Natural Resources↗