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Biomedical subjects

C Jolly

Publications and source records attributed to C Jolly.

At least 19 recordsLinked to original sources
PubMed2006

The use of a decremental dose regimen in patients treated with a chronic low-dose step-up protocol for WHO Group II anovulation: a prospective randomized multicentre study.

BACKGROUND: In women with chronic anovulation, the choice of the FSH starting dose and the modality of subsequent dose adjustments are critical in controlling the risk of overstimulation. The aim of this prospective randomized study was to assess the efficacy and safety of a decremental FSH dose regimen applied once the leading follicle was 10-13 mm in diameter in women treated for WHO Group II anovulation according to a chronic low-dose (CLD; 75 IU FSH for 14 days with 37.5 IU increment) step-up protocol. METHODS: Two hundred and nine subfertile women were treated with recombinant human FSH (r-hFSH) (Gonal-f) for ovulation induction according to a CLD step-up regimen. When the leading follicle reached a diameter of 10-13 mm, 158 participants were randomized by means of a computer-generated list to receive either the same FSH dose required to achieve the threshold for follicular development (CLD regimen) or half of this FSH dose [sequential (SQ) regimen]. HCG was administered only if not more than three follicles >or=16 mm in diameter were present and/or serum estradiol (E(2)) values were <1200 pg/ml. The primary outcome measure was the number of follicles >or=16 mm in size at the time of hCG administration. RESULTS: Clinical characteristics and ovarian parameters at the time of randomization were similar in the two groups. Both CLD and SQ protocols achieved similar follicular growth as regards the total number of follicles and medium-sized or mature follicles (>/=16 mm: 1.5 +/- 0.9 versus 1.4 +/- 0.7, respectively). Furthermore, serum E(2) levels were equivalent in the two groups at the time of hCG administration (441 +/- 360 versus 425 +/- 480 pg/ml for CLD and SQ protocols, respectively). The rate of mono-follicular development was identical as well as the percentage of patients who ovulated and achieved pregnancy. CONCLUSIONS: The results show that the CLD step-up regimen for FSH administration is efficacious and safe for promoting mono-follicular ovulation in women with WHO Group II anovulation. This study confirms that maintaining the same FSH starting dose for 14 days before increasing the dose in step-up regimen is critical to adequately control the risk of over-response. Strict application of CLD regimen should be recommended in women with WHO Group II anovulation.

Anovulation↗
PubMed2005

High-resolution ultrasonography of subretinal structure and assessment of retina degeneration in rat.

The purpose of this work was to evaluate the ability of 80 MHz ultrasonography to differentiate intra-retinal layers and quantitatively assess photoreceptor dystrophy in small animal models. Four groups of 10 RCS rats each (five dystrophic and five controls) were explored at 25, 35, 45 and 55 days post-natal (PN). A series of retina cross-sections were obtained ex vivo from outside intact eyes using an 80 MHz three-dimensional ultrasound backscatter microscope (20-microm-axial resolution). Ultrasound features of normal retina were correlated to those of corresponding histology and thickness measurements of photoreceptor segment and nuclear layers were performed on all groups. To show the ability of 80 MHz ultrasonography to distinguish the retinal degeneration in vivo, one RCS rat was explored at 25 and 55 days post-natal. Ultrasound image of normal retina displayed four distinct layers marked by reflections at neurites/nuclei interfaces and permitted to differentiate the photoreceptor segment and nuclear layers. The backscatter level from the retina was shown to be related to the size, density and organization of the intra-layer structure. Ultrasound thickness measurements highly correlated with histologic measurements. A thinning (p<0.05) of outer nuclear layer (ONL) was detected over time for controls and was thought to be assigned to retina maturation. Retinal degeneration started at PN35 and resulted in a more pronounced ONL thinning (p<0.05) over time. ONL degeneration was accompanied by segment layer thickening (p<0.05) at PN35 and thinning thereafter. These changes may indicate accumulation of outer segment debris at PN35 then progressive destruction. In vivo images of rat intra-retinal structure showed the ability of the method to distinguish the photoreceptor layer changes. Our results indicate that 80 MHz ultrasonography reveals intra-retinal layers and is sensitive to age and degenerative changes of photoreceptors. This technique has great potential to follow-up retinal dystrophy and therapeutic effects in vivo.

Animals↗
PubMed2002

Movements of cochlear implant electrodes inside the cochlea during insertion: an x-ray microscopy study.

BACKGROUND: There are no satisfactory, noninvasive techniques currently available to visualize the cochlear implant (CI) electrode in a dynamic state as it is advanced inside the cochlea. OBJECTIVE: This study describes a radiologic technique that can be used in temporal bones to monitor the electrode position in real time and to visualize the basilar membrane. METHODS: A cochleostomy was performed in accordance with the normal procedure for cochlear implantation in seven fresh cadaveric temporal bones. A special x-ray tube (Microfocus; Focus, Wunstorf, Germany) with a spot size of 1 microm and fluoroscopy were used for continuous videotape imaging of the advancing electrode in the cochlea. Conventional electrodes (MED-EL 40+; MED-EL, Innsbruck, Austria) and prototypes of perimodiolar electrodes (MED-EL), with varying thicknesses and angles of insertion, were used for the study. Finally, contrast liquid (Ultravist; Berlex Imaging, Schering, Germany) was injected into the scala vestibuli through the stapes footplate. RESULTS: The advancing electrode carrier was clearly visible at x20 magnification. With the perimodiolar electrodes, deep insertion was impossible if the guiding wire was too rigid, and retraction occurred if the wire was soft. The intact nature of the basilar membrane could be confirmed by the sequential filling of scala vestibuli and the scala tympani. CONCLUSION: To our knowledge, this is the first noninvasive study demonstrating continuous visualization with high-resolution and x-ray magnification of CI electrode advancement inside the intact cochlea. Our technique can be used for the development of CI electrodes with optimal design characteristics, especially stiffness. Visualization of the basilar membrane will influence the insertion techniques when CIs are developed for patients with residual hearing.

Basilar Membrane↗
PubMed2001

Insights into the catalytic mechanism of HlyC, the internal protein acyltransferase that activates Escherichia coli hemolysin toxin.

Hemolysin, a toxic protein secreted by pathogenic Escherichia coli, is converted from nontoxic prohemolysin, proHlyA, to toxic hemolysin, HlyA, by an internal protein acyltransferase, HlyC. Acyl-acyl carrier protein (ACP) is the essential acyl donor. The acyltransferase reaction proceeds through two partial reactions and entails formation of a reactive acyl-HlyC intermediate [Trent, M. S., Worsham, L. M., and Ernst-Fonberg, M. L. (1999) Biochemistry 38, 9541-9548]. The ping pong kinetic mechanism implied by these findings was validated using two different acyl-ACP substrates, thus verifying the independence of the previously demonstrated two partial reactions. Assessments of the stability of the acyl-HlyC intermediate revealed an increased stability at pH 8.6 compared to more acidic pHs. Mutations of a single conserved histidine residue essential for catalysis gave minimal activity when substituted with a tyrosine residue and no activity with a lysine residue. Unlike numerous other His23 mutants, however, the H23K enzyme showed significant acyl-HlyC formation although it was unable to transfer the acyl group from the proposed amide bond intermediate to proHlyA. These findings are compatible with transient formation of acyl-His23 during the course of HlyC catalysis. The effects of several other single site-directed mutations of conserved residues of HlyC on different portions of the reaction progress were examined using a 39 500 kDa fragment of proHlyA which was a more effective substrate than intact proHlyA.

Acylation↗
PubMed2001

Synthesis and biological evaluation of sialylmimetics as rotavirus inhibitors.

Rotaviruses cause severe gastroenteritis in infants and are estimated to be responsible for over 600 000 deaths annually, primarily in developing countries. The development of potential inhibitors of this virus is therefore of great interest, particularly since the safety and efficacy of rotaviral vaccines has recently been questioned. This study describes the synthesis of a variety of compounds that can be considered as mimetics of N-acetylneuraminic acid thioglycosides and the subsequent in vitro biological evaluation of these sialylmimetics as inhibitors of rotaviral infection. Our results show that readily accessible carbohydrate-based compounds have the potential to act as inhibitors of rotaviral replication in vitro, presumably through inhibition of the rotaviral adhesion process.

Animals↗
PubMed2001

[Visualization of cochlear implant electrode movements in the cochlea by using x-ray microscopy].

BACKGROUND: The movements of the electrode cable of a cochlear implant inside the cochlea during the insertion procedure generally are invisible, even in temporal bone experiments. Yet, the development of new designs of electrodes, their positioning near to the modiolus etc. requires an exact knowledge on the dynamic behaviour of the electrodes inside the cochlea. The exclusive method for looking through the undamaged cochlea walls is by x-ray technique. METHODS: A specific x-ray tube with a focal spot size of barely 5 microns allows useful direct magnifications of more than 20-30 times. We performed temporal bone experiments with this tube and studied the behaviour of conventional and perimodiolar electrode cables of a MedEl-Cl during the insertion procedure under fluoroscopic viewing. RESULTS: The high resolution imaging revealed the influence of stiffness of the electrode cable on the insertion depth of a conventional electrode. If the angle of the direction of insertion was too steep, the resulting kinking of the cable at the medial wall of the basal turn was instantly visible. The direct visualisation of the movements of the cable was useful in optimizing the design and stiffness of various prototypes of perimodiolar electrodes for a deep insertion. CONCLUSIONS: The dynamic examination technique disclosed that the stiffness of actual electrode cables is not optimally adapted to the form of the cochlear cavity for deep insertion. The non-destructive visualisation technique will facilitate the development of advanced electrode design, especially for various concepts of perimodiolar electrodes.

Cochlea↗
PubMed2001

Stress-specific activation and repression of heat shock factors 1 and 2.

Vertebrate cells express a family of heat shock transcription factors (HSF1 to HSF4) that coordinate the inducible regulation of heat shock genes in response to diverse signals. HSF1 is potent and activated rapidly though transiently by heat shock, whereas HSF2 is a less active transcriptional regulator but can retain its DNA binding properties for extended periods. Consequently, the differential activation of HSF1 and HSF2 by various stresses may be critical for cells to survive repeated and diverse stress challenges and to provide a mechanism for more precise regulation of heat shock gene expression. Here we show, using a novel DNA binding and detection assay, that HSF1 and HSF2 are coactivated to different levels in response to a range of conditions that cause cell stress. Above a low basal activity of both HSFs, heat shock preferentially activates HSF1, whereas the amino acid analogue azetidine or the proteasome inhibitor MG132 coactivates both HSFs to different levels and hemin preferentially induces HSF2. Unexpectedly, we also found that heat shock has dramatic adverse effects on HSF2 that lead to its reversible inactivation coincident with relocalization from the nucleus. The reversible inactivation of HSF2 is specific to heat shock and does not occur with other stressors or in cells expressing high levels of heat shock proteins. These results reveal that HSF2 activity is negatively regulated by heat and suggest a role for heat shock proteins in the positive regulation of HSF2.

3T3 Cells↗
PubMed2000

Role of the heat shock response and molecular chaperones in oncogenesis and cell death.

Exposure of cells to conditions of environmental stress-including heat shock, oxidative stress, heavy metals, or pathologic conditions, such as ischemia and reperfusion, inflammation, tissue damage, infection, and mutant proteins associated with genetic diseases-results in the inducible expression of heat shock proteins that function as molecular chaperones or proteases. Molecular chaperones are a class of proteins that interact with diverse protein substrates to assist in their folding, with a critical role during cell stress to prevent the appearance of folding intermediates that lead to misfolded or otherwise damaged molecules. Consequently, heat shock proteins assist in the recovery from stress either by repairing damaged proteins (protein refolding) or by degrading them, thus restoring protein homeostasis and promoting cell survival. The events of cell stress and cell death are linked, such that molecular chaperones induced in response to stress appear to function at key regulatory points in the control of apoptosis. On the basis of these observations-and on the role of molecular chaperones in the regulation of steroid aporeceptors, kinases, caspases, and other protein remodeling events involved in chromosome replication and changes in cell structure-it is not surprising that the heat shock response and molecular chaperones have been implicated in the control of cell growth. In this review, we address some of the molecular and cellular events initiated by cell stress-the interrelationships between stress signaling, cell death, and oncogenesis-and chaperones as potential targets for cancer diagnosis and treatment.

Animals↗
PubMed1999

Intron-independent association of splicing factors with active genes.

The cell nucleus is organized as discrete domains, often associated with specific events involved in chromosome organization, replication, and gene expression. We have examined the spatial and functional relationship between the sites of heat shock gene transcription and the speckles enriched in splicing factors in primary human fibroblasts by combining immunofluorescence and fluorescence in situ hybridization (FISH). The hsp90alpha and hsp70 genes are inducibly regulated by exposure to stress from a low basal level to a high rate of transcription; additionally the hsp90alpha gene contains 10 introns whereas the hsp70 gene is intronless. At 37 degrees C, only 30% of hsp90alpha transcription sites are associated with speckles whereas little association is detected with the hsp70 gene, whose constitutive expression is undetectable relative to the hsp90alpha gene. Upon exposure of cells to heat shock, the heavy metal cadmium, or the amino acid analogue azetidine, transcription at the hsp90alpha and hsp70 gene loci is strongly induced, and both hsp transcription sites become associated with speckles in >90% of the cells. These results reveal a clear disconnection between the presence of intervening sequences at specific gene loci and the association with splicing factor-rich regions and suggest that subnuclear structures containing splicing factors are associated with sites of transcription.

Azetidines↗
PubMed1999

Rapid and reversible relocalization of heat shock factor 1 within seconds to nuclear stress granules.

Heat shock factor 1 (HSF1) is essential for the stress-induced expression of heat shock genes. On exposure to heat shock, HSF1 localizes within seconds to discrete nuclear granules. On recovery from heat shock, HSF1 rapidly dissipates from these stress granules to a diffuse nucleoplasmic distribution, typical of unstressed cells. Subsequent reexposure to heat shock results in the rapid relocalization of HSF1 to the same stress granules with identical kinetics. Although the appearance of HSF1 stress granules corresponds to the hyperphosphorylated, trimeric DNA-binding state of HSF1 and correlates temporally with the inducible transcription of heat shock genes, they are also present in heat-shocked mitotic cells that are devoid of transcription. This finding suggests a role for HSF1 stress granules as a nuclear compartment for the temporal regulation and spatial organization of HSF1 activity and reveals new features of the dynamics of nuclear organization.

Biological Transport↗
PubMed1999

Stress and the cell nucleus: dynamics of gene expression and structural reorganization.

A growing number of experimental observations reveal that the cell nucleus is functionally compartmentalized yet organized to ensure a dynamic response to events that influence nuclear activities. The cellular and molecular response to physiological and environmental stress induces a rapid and transient change in gene expression associated with major changes in nuclear architecture that impacts on signals involved in cell growth. In this review, we will address the effects of stress on the functional compartmentation of the cell nucleus and the dynamic reorganization of nuclear structures and function.

Animals↗
PubMed1998

Genomic structure and chromosomal mapping of the mouse STOP gene (Mtap6).

The microtubule associated protein STOP (Stable Tubule Only Polypeptide) is a calmodulin-regulated protein able to induce a high degree of microtubule stability. STOP is abundant in neurons which contain large subpopulations of stable microtubules. Genomic clones spanning 67 kb and encompassing the mouse STOP gene (Mtap6) have been isolated and characterized. These clones derive from a single gene mapping to the E2-F1 region of mouse chromosome 7. The gene is composed of 4 exons that exhibit conventional vertebrate splicing sequences. Transcription of the gene initiate at multiple sites in a 85 nucleotide region located 530 bases upstream the translation initiation codon. Accordingly, the 5' flanking region of the gene lacks a TATA box or an initiator element at usual position. The protein encoded by the mouse STOP gene (Mtap6) is composed of 906 amino acids and presents a 91% identities with the rat brain STOP.

Amino Acid Sequence↗
PubMed1998

Contribution of growing RNA molecules to the nuclear transcripts foci observed by FISH.

The focal distributions of RNAs observed using fluorescence in situ hybridization (FISH) in the cell nucleus may correspond either to RNAs in the course of transcription or essentially to accumulation of full-length transcripts at the sites of transcription. To determine to what extent nuclear transcript foci represent growing RNA molecules, uninterrupted hsp70 transcripts were detected by FISH in heat-shocked human fibroblasts using two probes specific for the 5' or for the 3' end of the transcripts. By comparing the size of the signals obtained with each probe, we show that transcript foci mainly represent accumulations of full-length transcripts at their site of transcription. A major contribution of RNAs in the course of transcription to the transcript foci is observed only during the first minutes of gene induction. These observations suggest the existence of a rate-limiting step in the release of newly synthesized transcripts from their site of transcription, which is independent from the step of intron excision.

Cell Nucleus↗
PubMed1997

Analysis of the transcriptional activity of amplified genes in tumour cells by fluorescence in situ hybridization.

In this paper we present a new application of the detection of nuclear transcripts by fluorescence in situ hybridization (FISH) for studying the transcriptional activity of amplified genes in tumour cells. As a model, we have used the A431 cell line in which several amplification sites have been identified. We focused on two amplified regions: (1) the 6p12 region, which was found amplified by using comparative genomic hybridization, and which contains an amplification of the hsp90 beta gene; (2) the 7p12-p13 region, which displays a 20- to 30-fold amplification of the gene encoding the epidermal growth factor receptor (EGFr). By using FISH to detect nuclear transcripts, we show that the extra-copies of the hsp90 beta and EGFr genes are actively transcribed within the sites of amplification. This work illustrates the potential of this method as a tool for functional in situ cytogenetic analyses.

Chromosome Mapping↗
PubMed1997

Optimization of nuclear transcript detection by FISH and combination with fluorescence immunocytochemical detection of transcription factors.

Detection of specific nuclear transcripts by fluorescence in situ hybridization (FISH) has constituted a major breakthrough in the study of the organization of transcription in the cell nucleus. Using the model of heat shock genes, we present an optimized procedure for nuclear transcripts that provides high efficiency for RNA detection and good preservation of cell morphology and nuclear texture. Using this procedure, we designed an original high-efficiency methodology combining FISH and fluorescence immunocytochemistry (FICC), which is used here for the simultaneous detection of heat-shock protein (hsp) nuclear transcripts and the specific heat-shock transcription factor 1 (HSF1). We show that the nuclear accumulation sites of HSF1 in heat-shocked cells do not correspond to the sites of transcription of the hsp70 gene.

Cell Nucleus↗
PubMed1997

HSF1 transcription factor concentrates in nuclear foci during heat shock: relationship with transcription sites.

In this paper, we show that upon heat shock, HSF1 concentrates in the nucleus of diploid human fibroblasts in two large foci. The relative distribution of HSF1 nuclear foci and active heat shock protein (hsp) genes was investigated by combining fluorescence in situ hybridization (FISH) for the detection of hsp nuclear transcripts and immunofluorescence for the detection of HSF1. We show that the HSF1 foci are distinct from the sites of hsp70 and hsp90 genes transcription. This is the second report of ploidy-dependent foci of transcription factors that are independent of their specific transcription sites. However, the correlation between the number of HSF1 foci and the ploidy of the cells strongly supports the existence of a specific chromosomal target for HSF1 foci.

Apoptosis↗