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At least 199 records · Page 11Linked to original sources
PubMed1986

Thyrotropin regulates thyrotroph responsiveness to dopamine in vitro.

The effect of conditioned vs. fresh culture medium on the dopaminergic inhibition of TSH and PRL secretion by primary cultures of male rat anterior pituitary cells has been studied. In the presence of conditioned medium (that had been in contact with the cells over the 3-day culture period) 10(-6) M dopamine (DA) inhibited PRL secretion by 50% and TSH secretion by 30%. After 4 h of incubation with fresh medium 10(-6) M DA still inhibited PRL secretion by 50% but increased TSH release by 20%. TSH release was rapid and could be prevented by 10(-6) M prazosin, an alpha 1 adrenoreceptor antagonist. Fresh medium did not alter TRH induced TSH release. In parallel cultures and under identical conditions fresh medium reduced [3H]dihydroergocryptine (DHE) binding to DA receptors from 2.5 +/- 0.4 fmol/10(5) cells to 0.95 +/- 0.3 fmol/10(5) cells (means +/- SEM, n = 5, P less than 0.001). The effect of fresh medium was dose dependent against the dopaminergic inhibition of TSH secretion and against DA receptor binding. If 1 mU TSH was included, in fresh medium, the dopaminergic inhibition of TSH secretion remained unchanged and [3H]DHE binding to DA receptors did not fall. The rank order of potency of thyroid stimulators was bovine TSH (21 U/mg) greater than semipurified bovine TSH (Thytropar, 1.4 U/mg) greater than endogenous rat TSH (0.03 U/mg expressed as NIADDK-rat TSH-RP2) greater than Graves' immunoglobulin G (0.01 U/mg) when either DA or bromocriptine was used as the dopaminergic agonist. When anterior pituitary cells from hypothyroid rats were examined, the effects of culture medium on the dopaminergic inhibition of TSH and on DA receptor binding were approximately twice those observed in normal cells, but the inclusion of 1 mU TSH in the fresh medium completely prevented the loss of DA function and binding. PRL, human CG, ACTH, insulin, glucagon, and heat-inactivated TSH were unable to prevent the effect of medium replacement on dopaminergic inhibition of TSH and DA receptor binding. The data suggest a mechanism whereby TSH may control its own secretion via DA.

Adrenocorticotropic Hormone↗
PubMed1994

Androgen regulation of gene expression in primary epithelial cells of the mouse kidney.

In proximal tubule cells of the mouse kidney, transcription of a number of genes is induced by androgens. Although a great deal of molecular and genetic information on the induction process has accumulated, the lack of an appropriate cell culture system for DNA transfection studies has hampered efforts to identify and characterize in detail the molecular factors that mediate the response. In the present paper, we have examined a primary renal epithelial cell culture system. We show that in response to androgens, these cells undergo induction of five messenger RNAs that are induced in the intact kidney; thus, the effects of androgens on renal gene expression derive from a direct action of the hormone on proximal tubule cells. The response does not occur in cells from Tfm animals, indicating that androgen receptor is required. Differences in patterns of androgen-inducible messenger RNA expression between mouse species are reflected by similar differences in the cultured cells. Interestingly, the kinetics of induction in culture seem to be distinct from those in the intact kidney, suggesting that a factor or factors differing between the whole animal and tissue culture environments influence the response. Transient transfection experiments with the primary cells showed that the 5'-flanking region of the androgen-regulated RP2 gene, which includes nucleotides -1500 to +42 and contains a glucocorticoid response element that binds the androgen receptor, does not mediate androgen-responsive transcription; thus, this region, and the glucocorticoid response element within it, are either insufficient for, or are not involved in, the gene's response to hormone.

Androgens↗
PubMed2003

Mutation of IVS2 -12A/C>G in combination with 707-714delGAGACTAC in the CYP21 gene is caused by deletion of the C4-CYP21 repeat module with steroid 21-hydroxylase deficiency.

More than 90% of the cases of congenital adrenal hyperplasia are caused by mutations of the CYP21 gene. Approximately 75% of the defective CYP21 genes are generated through intergenic recombination, termed apparent gene conversion, from the neighboring CYP21P pseudogene. Among them, mutation of the aberrant splicing donor site of IVS2 -12A/C>G at nucleotide (nt) 655 is believed to be a result derived from this mechanism and is the most prevalent case among all ethnic groups. However, mutation of 707-714delGAGACTAC rarely exists alone, although this locus is a distance of 53 nt away from IVS2 -12A/C>G. From the molecular characterization of the mutation of IVS2 -12A/C>G combined with 707-714delGAGACTAC in patients with congenital adrenal hyperplasia, we found that it appeared to be in a 3.2-rather than a 3.7-kb fragment generated by Taq I digestion in a PCR product of the CYP21 gene. Interestingly, the 5' end region of such a CYP21 haplotype had CYP21P-specific sequences. Our results indicate that the coexistence of these two mutations is caused by deletion of the CYP21P, XA, RP2, and C4B genes and intergenic recombination in the C4-CYP21 repeat module. Surprisingly, this kind of the haplotype of the mutated CYP21 gene has not been reported as a gene deletion.

Adrenal Hyperplasia, Congenital↗
PubMed1991

Pathfinding in the central nervous system and periphery by identified embryonic Drosophila motor axons.

We have studied the pattern of axon outgrowth from the identified embryonic Drosophila motorneurons, RP1, RP3, RP4 and RP5, from the onset of axonogenesis to the time of arborization over target muscles. Lucifer Yellow was intracellularly injected into each of these neurons to obtain a detailed description of the morphology of their growth cones and of the pathways that they follow. We have divided the sequence of axon growth from these neurons into five major phases. In the first phase, the growth cone of each RP axon grows medially along its contralateral homologue along the anterior commissure. Each RP axon follows a separate path across the midline in the anterior commissure. After crossing the ventral midline, the axons wrap around specific contralateral RP somata. In the second phase, each axon grows posteriorly and dorsally down the contralateral longitudinal connective, fasciculating with the other RP axons. In the third phase, the axons turn into the intersegmental nerve via the anterior nerve root, then cross over to the segmental nerve, before contacting the external surfaces of intermediate muscles 15/16. They do not fasciculate with the pioneering aCC and RP2 axons at this time. In the fourth phase, the axons advance laterally across the ventral muscle group. During this phase, each axon extends processes over a number of inappropriate muscles as well as contacting its correct, target muscle. In the final phase, the processes to inappropriate muscles are withdrawn, generating the mature pattern of motor axon projections. There is no consistent, clear difference between the RP motorneurons in the relative timing of axon outgrowth.

Animals↗
PubMed1994

The Drosophila miti-mere gene, a member of the POU family, is required for the specification of the RP2/sibling lineage during neurogenesis.

The Drosophila POU gene miti-mere (previously known as pdm2) has a complex spatial and temporal pattern of expression during early development; initially it is expressed in gap-gene-like pattern, then in 14 stripes and finally in a subset of the cells in the developing CNS and PNS. To study the function of this gene during development, we generated a 'synthetic anti-morphic mutation' by expressing a truncated version of the miti protein from a constitutive hsp83 and an inducible hsp70 promoter. We show that these delta miti transgenes behave like classical antimorphic mutations. Using these dominant negative transgenes, together with deletions and a duplication for the gene, we show that miti is required during segmentation and neurogenesis. We have also used temperature-shift experiments with the hsp70 delta miti transgene to demonstrate that miti function in segmentation is distinct and separable from its function during neurogenesis. In segmentation, miti appears to be required in the specification of the segments A2 and A6. In the CNS, miti is required for the elaboration of the NB4-2-->GMC-1-->RP2/sib lineage. miti is initially required in this lineage to establish the identity of the parental ganglion mother cell, GMC-1. miti must then be down-regulated to allow the asymmetric division of GMC-1 into the RP2 and its sibling cell.

Animals↗
PubMed1997

Genetic separation of the neural and cuticular patterning functions of gooseberry.

In addition to their role in the specification of the epidermal pattern in each segment, several segment polarity genes, including gooseberry (gsb), specify cell fate in the Drosophila central nervous system (CNS). Analyses of the gsb CNS phenotype have been complicated by the fact that the previously available gsb mutants, all caused by cytologically visible deficiencies, have severe segmentation defects and also lack a number of additional genes. We have characterized two novel gsb mutants which, due to their hypomorphic nature, have CNS defects, but have only weak or no segmentation defects. These gsb alleles, as well as gsb rescue experiments, have allowed us to determine which aspects of the deficiency mutant phenotypes can be attributed to loss of gsb. gsb mutants lack U and CQ neurons, have duplicated RP2 neurons, and display posterior commissure defects. gsb neural defects, as well as the gsb cuticle defect, are differentially sensitive to the level of functional Gsb. We have used one of the novel gsb alleles in order to understand the genetic interactions between gsb, wingless (wg), and patched (ptc) during the patterning of the ventral neuroectoderm. In contrast to epidermal patterning, where Gsb is required to maintain wg transcription, we find that Gsb antagonizes the Wg signal that confers neuroblast (NB) 4-2 fate.

Animals↗
PubMed2000

Axon pathfinding proceeds normally despite disrupted growth cone decisions at CNS midline.

Axons in the bilateral brain of Drosophila decide whether or not to cross the midline before following their specific subsequent pathways. In commissureless mutants, the RP3 and V motoneuron axons often fail to cross the midline but subsequently follow the mirror-image pathways and innervate corresponding muscle targets on the ipsilateral side. Conversely, in roundabout mutants, the RP2 and aCC motoneuron axons sometimes cross the midline abnormally but their subsequent pathways and synaptic targeting are the perfect mirror images of those seen in wild type. Furthermore, within a single segment of these mutants, bilateral pairs of motoneuron axons can make their midline decisions independently of each other. Thus, neither the growth cones' particular molecular experience nor the decision at the midline caused by these mutations affects their ability to respond normally to subsequently presented cues.

Animals↗
PubMed2001

Slit signaling promotes the terminal asymmetric division of neural precursor cells in the Drosophila CNS.

The bipotential Ganglion Mother Cells, or GMCs, in the Drosophila CNS asymmetrically divide to generate two distinct post-mitotic neurons. Here, we show that the midline repellent Slit (Sli), via its receptor Roundabout (Robo), promotes the terminal asymmetric division of GMCs. In GMC-1 of the RP2/sib lineage, Slit promotes asymmetric division by down regulating two POU proteins, Nubbin and Mitimere. The down regulation of these proteins allows the asymmetric localization of Inscuteable, leading to the asymmetric division of GMC-1. Consistent with this, over-expression of these POU genes in a late GMC-1 causes mis-localization of Insc and symmetric division of GMC-1 to generate two RP2s. Similarly, increasing the dosage of the two POU genes in sli mutant background enhances the penetrance of the RP2 lineage defects whereas reducing the dosage of the two genes reduces the penetrance of the phenotype. These results tie a cell-non-autonomous signaling pathway to the asymmetric division of precursor cells during neurogenesis.

Animals↗
PubMed2004

Regulation of neuronal excitability through pumilio-dependent control of a sodium channel gene.

Dynamic changes in synaptic connectivity and strength, which occur during both embryonic development and learning, have the tendency to destabilize neural circuits. To overcome this, neurons have developed a diversity of homeostatic mechanisms to maintain firing within physiologically defined limits. In this study, we show that activity-dependent control of mRNA for a specific voltage-gated Na+ channel [encoded by paralytic (para)] contributes to the regulation of membrane excitability in Drosophila motoneurons. Quantification of para mRNA, by real-time reverse-transcription PCR, shows that levels are significantly decreased in CNSs in which synaptic excitation is elevated, whereas, conversely, they are significantly increased when synaptic vesicle release is blocked. Quantification of mRNA encoding the translational repressor pumilio (pum) reveals a reciprocal regulation to that seen for para. Pumilio is sufficient to influence para mRNA. Thus, para mRNA is significantly elevated in a loss-of-function allele of pum (pum(bemused)), whereas expression of a full-length pum transgene is sufficient to reduce para mRNA. In the absence of pum, increased synaptic excitation fails to reduce para mRNA, showing that Pum is also necessary for activity-dependent regulation of para mRNA. Analysis of voltage-gated Na+ current (I(Na)) mediated by para in two identified motoneurons (termed aCC and RP2) reveals that removal of pum is sufficient to increase one of two separable I(Na) components (persistent I(Na)), whereas overexpression of a pum transgene is sufficient to suppress both components (transient and persistent). We show, through use of anemone toxin (ATX II), that alteration in persistent I(Na) is sufficient to regulate membrane excitability in these two motoneurons.

Action Potentials↗
PubMed2004

Differential effects of Drosophila mastermind on asymmetric cell fate specification and neuroblast formation.

During neurogenesis in the ventral nerve cord of the Drosophila embryo, Notch signaling participates in the pathway that mediates asymmetric fate specification to daughters of secondary neuronal precursor cells. In the NB4-2 --> GMC-1 --> RP2/sib lineage, a well-studied neuronal lineage in the ventral nerve cord, Notch signaling specifies sib fate to one of the daughter cells of GMC-1. Notch mediates this process via Mastermind (Mam). Loss of function for mam, similar to loss of function for Notch, results in GMC-1 symmetrically dividing to generate two RP2 neurons. Loss of function for mam also results in a severe neurogenic phenotype. In this study, we have undertaken a functional analysis of the Mam protein. We show that while ectopic expression of a truncated Mam protein induces a dominant-negative neurogenic phenotype, it has no effect on asymmetric fate specification. This truncated Mam protein rescues the loss of asymmetric specification phenotype in mam in an allele-specific manner. We also show an interallelic complementation of loss-of-asymmetry defect. Our results suggest that Mam proteins might associate during the asymmetric specification of cell fates and that the N-terminal region of the protein plays a role in this process.

Alleles↗
PubMed2006

The survival of pathogens in soil treated with wastewater sludge and in potatoes grown in such soil.

The prevalence of pathogens on potatoes (Solanum tuberosum) grown in soil amended with a pathogen rich wastewater sludge was investigated. Bacteria of the family Enterobacteriaceae are important pathogens causing intestinal and systemic illness of humans and other animals. Type B sludge was used. Sludges investigated are the high metal and the low metal sludges. Microorganisms in the sludge-amended soil were using culture-based technique. Salmonella and E. coli were observed in tested soil samples. No microorganisms were isolated from control samples taken throughout the process of the experiment. At harvest time, some of the potato samples from LMS soil were contaminated. These potatoes were subjected to further investigation using molecular techniques (polymerase chain reaction) with fD1 and rP2 as primers. Organisms identified from the sequenced potato peel samples with the BLAST search tool included Enterobacter agglomerans (Pantoea agglomerans), several Buttiauxella spp., Pectobacterium spp., Erwinia spp. and a few Pantoea spp. Other than the E. agglomerans, which is commonly found in the gut and upper respiratory tract of humans and in the environment, all the other species identified were found to be mainly either plant or soil pathogens. The E. agglomerans are not primary pathogens but secondary opportunistic pathogens particularly in immunocompromised individuals. These results suggest that growing high risk crops using wastewater sludge contaminated soil may lead to limited infestation of produce with primary pathogens. It appears that the use of HMS due to early pathogen die-off provides less risk of infection than the LMS. However, proper treatment of wastewater sludge to reduce pathogen load is essential prior to its use as soil conditioner.

Escherichia coli↗
PubMed1991

Clinical variability in a family with X-linked retinal dystrophy and the locus at the RP3 site.

One large Australian family with X-linked retinal dystrophy was found to have extreme clinical variability in the hemizygotes. One member had the typical rod-cone disease, three had the cone-rod pattern and one had macroscopic changes in the macular area only, but with low potentials in the ERG. The locus for the disease was found to be distal to L1.28 at Xp21, the site for RP3. From a study of case histories reported it seems that clinical variability can be a common feature of X-linked retinitis pigmentosa (XLRP) with the locus at Xp11.3 (RP2) or at Xp21 (RP3), and this family may well be categorized as XLRP.

Adult↗
PubMed1991

Carrier detection in X-linked retinitis pigmentosa by multipoint DNA analysis. Problems due to genetic heterogeneity.

DNA diagnosis of X-linked retinitis pigmentosa (XLRP) is hampered by its genetic heterogeneity, while a clinical subdivision is almost impossible to make. So far, diagnostic services have been offered only to those families in which linkage to one RP locus (RP2 or RP3) has been clearly established. In most families, however, the nature of the XLRP type cannot be distinguished on the basis of linkage analysis. Here the authors describe that in some families DNA diagnosis is nonetheless feasible, when polymorphic DNA markers are used which span the entire Xp21.1-Xcen region and when no recombination between these markers disturbs the phase.

Blotting, Southern↗
PubMed1992

A retrospective study of registered retinitis pigmentosa patients in The Netherlands.

A retrospective study was performed of patients with retinitis pigmentosa (RP) registered at the Department of Ophthalmogenetics of the Netherlands Ophthalmic Research Institute. The aim was to establish the relative frequencies of the genetic modes and to attempt a clinical subclassification. Of the 575 RP patients, 10.4% were X-linked, 22.4% autosomal dominant, 30.1% autosomal recessive, and 37.1% simplex cases. Clinical classification was inconclusive, and consequently correlation of phenotype to genotype impossible in most cases. One exception was the occurrence of a tapetal reflex, which seemed to differentiate between RP2 and RP3. Gene defects have not been detected so far in Dutch families with either autosomal dominant or autosomal recessive RP. In the future, simplex cases will have to be classified according to their genetic defects. It is probable that results of DNA studies may prove a better basis for classification of RP than clinical data.

Female↗
PubMed2000

[The role of preoperative staging for pancreatic cancer].

Despite the poor prognosis of pancreatic carcinoma patients, surgical resection remains the only potentially curative treatment. As it has been demonstrated that extended radical surgery does not lead to a better prognosis, accurate staging to select those patients who may benefit from resection is essential. According to the report of a national survey of pancreatic cancer in 1997, patients with S0 or S1, RP0 or RP1, and N0 or N1 disease have longer survival periods compared with patients with S2, RP2, and N2 disease. Therefore patients classified as Stage I, Stage II, or Stage III are recognized as candidates for surgical resection. Patients classified as Stage IVb because of positive P factor or positive H factor are selected for conservative treatment such as chemotherapy and irradiation. It remains to be clarified whether patients classified as Stage IVa should undergo surgical resection or not. Future prospective randomized studies of patients with Stage IVa disease will reveal whether surgical resection or chemoradiation is effective. Helical CT is useful to evaluate S and RP factors for definitive preoperative staging. CT-AP can reveal occult metastases to the liver. These preoperative evaluations should be evaluated along with histological findings.

Humans↗
PubMed2001

Altered electrical properties in Drosophila neurons developing without synaptic transmission.

We examine the role of synaptic activity in the development of identified Drosophila embryonic motorneurons. Synaptic activity was blocked by both pan-neuronal expression of tetanus toxin light chain (TeTxLC) and by reduction of acetylcholine (ACh) using a temperature-sensitive allele of choline acetyltransferase (Cha(ts2)). In the absence of synaptic activity, aCC and RP2 motorneurons develop with an apparently normal morphology and retain their capacity to form synapses. However, blockade of synaptic transmission results in significant changes in the electrical phenotype of these neurons. Specifically, increases are seen in both voltage-gated inward Na(+) and voltage-gated outward K(+) currents. Voltage-gated Ca(2+) currents do not change. The changes in conductances appear to promote neuron excitability. In the absence of synaptic activity, the number of action potentials fired by a depolarizing ramp (-60 to +60 mV) is increased and, in addition, the amplitude of the initial action potential fired is also significantly larger. Silencing synaptic input to just aCC, without affecting inputs to other neurons, demonstrates that the capability to respond to changing levels of synaptic excitation is intrinsic to these neurons. The alteration to electrical properties are not permanent, being reversed by restoration of normal synaptic function. Whereas our data suggest that synaptic activity makes little or no contribution to the initial formation of embryonic neural circuits, the electrical development of neurons that constitute these circuits seems to depend on a process that requires synaptic activity.

Acetylcholine↗
PubMed1999

[Gene diagnosis of X linked retinitis pigmentosa by linkage analysis].

OBJECTIVE: To establish a gene diagnosis method for X linked retinitis pigmentosa (XLRP). METHODS: Ten microsatellite markers were selected from the region where the RP2 and RP3 gene may be located at Xp21.1-p11.23. Haplotype analysis for XLRP pedigrees was used to determine the chromosome region which is RP related and whether this region was carried by the individuals we want to detect. RESULTS: The young female who is the RP carrier or the young boy who is the pre-symptom RP patient could be determined this way in 4 XLRP family. CONCLUSION: Haplotype analysis for XLRP Pedigrees is useful.

Adult↗
PubMed2002

Retinal histopathology of an XLRP carrier with a mutation in the RPGR exon ORF15.

X-linked retinitis pigmentosa comprises the severe forms of RP, with early onset of night blindness, rapid constriction of visual fields and eventual loss of central acuity. Of the five distinct XLRP loci identified on the X chromosome, mutations have been found only in the RP2 and RPGR genes. Of these, mutations in RPGR are more common, particularly in a mutational hot spot that was identified in the newly discovered exon ORF15. We report on an extended family with a microdeletion in RPGR exon ORF15 and the retinal histopathology of a female carrier of this mutation. We found a 1bp deletion at position 632 in exon ORF15 in affected members of family XLRP-319. This mutation alters the reading frame of the predicted RPGR protein, resulting in a premature stop codon. The mutation segregated with disease in three generations of the family and was associated with severe early onset retinal disease in affected men. The retina from a 75 year old carrier female donor had slight photoreceptor loss in the less diseased areas. More severe atrophy with retinal pigment epithelium (RPE) migration was present in areas of the mid- and far periphery. By immunocytochemistry, loss of rhodopsin labelling in rods was found in the areas of focal atrophy and loss of uniform cone spacing was apparent even in well preserved regions. Small multifocal areas of outer retinal degeneration were present in the better preserved regions of the eye. In these foci, rod and cone loss did not coincide. The dissociation of rod and cone degeneration in areas of focal disease is consistent with random X-inactivation early in embryonic development and the occurrence of distinct patterns of radial (rod) and tangential (cone) dispersion during clonal expansion early in photoreceptor differentiation.

Adult↗