Search PubMed⌕ Search

Biomedical subjects

F Long

Publications and source records attributed to F Long.

At least 19 recordsLinked to original sources
PubMed2006

SPINE workshop on automated X-ray analysis: a progress report.

The Structural Proteomics In Europe (SPINE) consortium contained a workpackage to address the automated X-ray analysis of macromolecules. The aim of this workpackage was to increase the throughput of three-dimensional structures while maintaining the high quality of conventional analyses. SPINE was able to bring together developers of software with users from the partner laboratories. Here, the results of a workshop organized by the consortium to evaluate software developed in the member laboratories against a set of bacterial targets are described. The major emphasis was on molecular-replacement suites, where automation was most advanced. Data processing and analysis, use of experimental phases and model construction were also addressed, albeit at a lower level.

Algorithms↗
PubMed2005

Rapid non-genomic inhibitory effects of glucocorticoids on human neutrophil degranulation.

BACKGROUND: Glucocorticoids acting as anti-inflammatory or immunosuppressive drugs have been shown to exert most of their effects genomically. Recent findings suggest that non-genomic activity might be relatively more important in mediating the therapeutic effects of high-dose pulsed glucocorticoid. However, few non-genomic anti-inflammatory effects were reported, much less non-genomic mechanisms. OBJECTIVE: This study was performed to investigate the nongenomic effects of glucocorticoids on human neutrophil degranulation. METHODS: Purified human neutrophils were pretreated with 6 alpha-methylprednisolone or hydrocortisone for 5 min, and then primed with N-formyl-methionyl-leucyl-phenylalanine (fMLP) (10(-6) M) or phorbol myristate acetate (PMA) (50 ng/ml) in the presence of cytochalasin B. The release of two markers of neutrophil granules, lactoferrin and myeloperoxidase, was measured by ELISA and enzymology methods respectively. RESULTS: Both 6 alpha-methylprednisolone (10(-5)-10(-4) M) and hydrocortisone (10(-4) M) showed significant inhibitory effects on neutrophil degranulation within 5 min after fMLP administration. For PMA stimulated degranulation, 6 alpha-methylprednisolone (10(-4) M) showed significant inhibitory effects (p < 0.01), while hydrocortisone (10(-4) M) only showed an inhibitory tendency (P > 0.05). Neither RU486 (10(-5) M) nor cycloheximide (10(-4) M) could alter the inhibitory effects of glucocorticoids. CONCLUSION: Our results demonstrate that megadoses of glucocorticoids exert rapid inhibitory effects on human neutrophil degranulation at the cellular level via a new mechanism that is independent of corticosteroid type II receptor occupation or protein synthesis. We infer that these effects may be very important when glucocorticoids act as anti-inflammatory drugs during pulse therapy.

Cell Degranulation↗
PubMed2005

[Multidetector CT for the diagnosis of congenital vascular anomalies and associated complications in newborns and infants].

PURPOSE: To assess the value of multidetector CT (MDCT) for evaluation of vascular anomalies (VA) and associated complications in newborns and infants. MATERIALS AND METHODS: Seventy-five children (mean age: 9 +/- 6 months, range: 2 weeks to 24 months) with VA were examined using MDCT (4-, 8- or 16-row; collimation 0.5-1.25 mm; scan time 7-30 s), which was performed under controlled ventilation or free breathing. Image quality was rated using a 5-point scale. Image findings were correlated to echocardiography, conventional catheter angiography (CCA), bronchoscopy, and intraoperative findings. RESULTS: High quality MDCT data were almost free of cardiac and respiratory motion. In all cases, VA morphology and topography in relation to adjacent structures, e. g. tracheal and esophageal compression caused by an aortic ring, could be assessed exactly and allowed the final diagnosis. Even aberrant vessels, such as aorto-pulmonary collaterals (MAPCA) with a diameter of less than 1 mm, could be identified and excellently visualized. Eighty percent (60/75) of all patients had benefited from the MDCT: in 31 patients CCA was neither necessary to perform surgical planning nor to exclude a VA; in an additional 29 patients radiation doses and sedation time due to interventional procedures could be reduced markedly. CONCLUSIONS: MDCT can now be regarded as the modality of choice as a minimally invasive, robust, and accurate technique for the diagnosis of complex VA, their potentially life-threatening complications and preoperative planning even in newborns and infants. Its accuracy for detecting VA appears equivalent to CCA while it is more accurate in delineating potential life-threatening complications.

Arteriovenous Malformations↗
PubMed2004

Migrating calcified enterolith and chronic anemia: an unusual case presentation of a Meckel's diverticulum.

Meckel's diverticulum is the most common congenital anomaly of the small intestine, occurring in about 2 % of the population. The most common complications associated with a Meckel's diverticulum include obstruction, bleeding, and inflammation (7, 9, 11, 18-20). The estimated lifetime risk of developing symptoms with a Meckel's diverticulum is 4-6 % (16), with the risks of complications decreasing with age. Stones within Meckel's diverticulum are recognized as a rare complication in the adult population (13,15). However, it has not been reported in the pediatric age group. The authors describe a 19-month-old male who presented with intermittent abdominal pain and vomiting, chronic microcytic anemia and a calcified stone in the lower abdomen, who was found to have a Meckel's enterolith.

Anemia↗
PubMed2003

A rare leucine codon in adpA is implicated in the morphological defect of bldA mutants of Streptomyces coelicolor.

Streptomycetes are mycelial bacteria that produce sporulating aerial hyphae on solid media. Bald (bld) mutants fail to form aerial mycelium under at least some conditions. bldA encodes the only tRNA species able to read the leucine codon UUA efficiently, implying the involvement of a TTA-containing gene in initiating aerial growth. One candidate for such a gene was bldH, because the bldH109 mutant of Streptomyces coelicolor resembles bldA mutants in some aspects. In the work reported here, adpAc, an S. coelicolor gene similar to the Streptomyces griseus A factor-regulated adpAg, was found to complement the bldH109 mutant partially at both single and multiple copies. The sequence of adpAc from the bldH109 mutant revealed a frameshift. A constructed in frame deletion of adpAc conferred a bald colony phenotype, and the mutant behaved like bldA mutants and bldH109 in its pattern of extracellular signal exchange. Both adpAc and adpAg contain a TTA codon. A TTA-free version of adpAc was engineered by replacing the TTA leucine codon with a cognate TTG leucine codon. The adpA(TTATTG) gene could partially restore aerial mycelium formation to a bldA mutant when it was followed in cis by the gene ornA, as in the natural chromosomal arrangement. This indicated that the UUA codon in adpAc mRNA is the principal target through which bldA influences morphological differentiation. It also implied that translational arrest at the UUA codon in adpAc mRNA caused a polar effect on the downstream ornA, and that the poor translation of both genes contributes extensively to the deficiency of aerial mycelium formation in bldA mutants. Unlike the situation in S. griseus, adpAc transcription does not depend on the host's -butyrolactone signalling system, at least in liquid cultures. In addition, sigma factor BldN, which is the homologue of an S. griseus sigma factor AdsA that is absent from adpAg mutants of S. griseus, was present in the constructed adpAc null mutant of S. coelicolor.

Bacterial Proteins↗
PubMed2001

Regulation of endochondral cartilage growth in the developing avian limb: cooperative involvement of perichondrium and periosteum.

The perichondrium and periosteum have recently been suggested to be involved in the regulation of limb growth, serving as potential sources of signaling molecules that are involved in chondrocyte proliferation, maturation, and hypertrophy. Previously, we observed that removal of the perichondrium and periosteum from tibiotarsi in organ culture resulted in an overall increase in longitudinal cartilage growth, suggesting negative regulation originating from these tissues. To determine if the perichondrium and periosteum regulate growth through the production of diffusible factors, we have tested various conditioned media from these tissues for the ability to modify cartilage growth in tibiotarsal organ cultures from which these tissues have been removed. Both negative and positive regulatory activities were detected. Negative regulation was observed with conditioned medium from (1) cell cultures of the region bordering both the perichondrium and the periosteum, (2) co-cultures of perichondrial and periosteal cells, and (3) a mixture of conditioned media from perichondrial cell cultures and periosteal cell cultures. The requirement for regulatory factors from both the perichondrium and periosteum suggests a novel mechanism of regulation. Positive regulation was observed with conditioned media from several cell types, with the most potent activity being from articular perichondrial cells and hypertrophic chondrocytes.

Animals↗
PubMed2001

CREB regulates hepatic gluconeogenesis through the coactivator PGC-1.

When mammals fast, glucose homeostasis is achieved by triggering expression of gluconeogenic genes in response to glucagon and glucocorticoids. The pathways act synergistically to induce gluconeogenesis (glucose synthesis), although the underlying mechanism has not been determined. Here we show that mice carrying a targeted disruption of the cyclic AMP (cAMP) response element binding (CREB) protein gene, or overexpressing a dominant-negative CREB inhibitor, exhibit fasting hypoglycaemia [corrected] and reduced expression of gluconeogenic enzymes. CREB was found to induce expression of the gluconeogenic programme through the nuclear receptor coactivator PGC-1, which is shown here to be a direct target for CREB regulation in vivo. Overexpression of PGC-1 in CREB-deficient mice restored glucose homeostasis and rescued expression of gluconeogenic genes. In transient assays, PGC-1 potentiated glucocorticoid induction of the gene for phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting enzyme in gluconeogenesis. PGC-1 promotes cooperativity between cyclic AMP and glucocorticoid signalling pathways during hepatic gluconeogenesis. Fasting hyperglycaemia is strongly correlated with type II diabetes, so our results suggest that the activation of PGC-1 by CREB in liver contributes importantly to the pathogenesis of this disease.

Adenoviridae↗
PubMed2001

Compression of the trachea by the innominate artery in a 2-month-old child.

SUMMARY. We utilized improved methods for assessing airway structure and function to define the clinical significance of the innominate artery syndrome. Both infant pulmonary function tests (IPFT) and noninvasive controlled ventilation computed tomography (CVCT) were used, along with traditional diagnostic techniques in a 2-month-old child with compression of the trachea by the innominate artery. These tests provided objective documentation of functional impairment before surgery and improvement postoperatively. These tests should aid in the understanding of this controversial syndrome and help to further define treatment options.

Airway Obstruction↗
PubMed2001

Genetic manipulation of hedgehog signaling in the endochondral skeleton reveals a direct role in the regulation of chondrocyte proliferation.

Indian hedgehog (Ihh), one of the three mammalian hedgehog (Hh) proteins, coordinates proliferation and differentiation of chondrocytes during endochondral bone development. Smoothened (Smo) is a transmembrane protein that transduces all Hh signals. In order to discern the direct versus indirect roles of Ihh in cartilage development, we have used the Cre-loxP approach to remove Smo activity specifically in chondrocytes. Animals generated by this means develop shorter long bones when compared to wild-type littermates. In contrast to Ihh mutants (Ihh(n)/Ihh(n)), chondrocyte differentiation proceeds normally. However, like Ihh(n)/Ihh(n) mice, proliferation of chondrocytes is reduced by about 50%, supporting a direct role for Ihh in the regulation of chondrocyte proliferation. Moreover, by overexpressing either Ihh or a constitutively active Smo allele (Smo*) specifically in the cartilage using the bigenic UAS-Gal4 system, we demonstrate that activation of the Ihh signaling pathway is sufficient to promote chondrocyte proliferation. Finally, expression of cyclin D1 is markedly downregulated when either Ihh or Smo activity is removed from chondrocytes, indicating that Ihh regulates chondrocyte proliferation at least in part by modulating the transcription of cyclin D1. Taken together, the present study establishes Ihh as a key mitogen in the endochondral skeleton.

Animals↗
PubMed2001

The CREB family of activators is required for endochondral bone development.

We have evaluated the importance of the CREB family of transcriptional activators for endochondral bone formation by expressing a potent dominant negative CREB inhibitor (A-CREB) in growth plate chondrocytes of transgenic mice. A-CREB transgenic mice exhibited short-limbed dwarfism and died minutes after birth, apparently due to respiratory failure from a diminished rib cage circumference. Consistent with the robust Ser133 phosphorylation and, hence, activation of CREB in chondrocytes within the proliferative zone of wild-type cartilage during development, chondrocytes in A-CREB mutant cartilage exhibited a profound decrease in proliferative index and a delay in hypertrophy. Correspondingly, the expression of certain signaling molecules in cartilage, most notably the Indian hedgehog (Ihh) receptor patched (Ptch), was lower in A-CREB expressing versus wild-type chondrocytes. CREB appears to promote Ptch expression in proliferating chondrocytes via an Ihh-independent pathway; phospho-CREB levels were comparable in cartilage from Ihh(-/-) and wild-type mice. These results demonstrate the presence of a distinct signaling pathway in developing bone that potentiates Ihh signaling and regulates chondrocyte proliferation, at least in part, via the CREB family of activators.

Animals↗
PubMed1999

Atypical presentation of Clostridium difficile colitis in patients with cystic fibrosis.

OBJECTIVE: This report describes the unusual presentation of Clostridium difficile colitis in five patients with cystic fibrosis and the role of CT in first suggesting the correct diagnosis in this group of patients. Because of the absence of watery diarrhea and the presence of abdominal bloating and decreased stooling, cystic fibrosis patients with C. difficile colitis will be treated for stool impaction, meconium ileus equivalent, or distal intestinal obstruction syndrome. CT of the abdomen, performed in these five patients because of their lack of improvement after standard therapy for stool impaction, showed an extensive pancolitis later confirmed to be caused by C. difficile infection. CONCLUSION: In patients with cystic fibrosis, imaging findings of a pancolitis should raise the possibility of C. difficile colitis despite the lack of watery diarrhea. Anticlostridial treatment can be initiated before bacteriologic confirmation is obtained.

Adult↗
PubMed1999

Hydrogen-stretching vibrational circular dichroism spectroscopy: absolute configuration and solution conformation of selected pharmaceutical molecules.

The vibrational circular dichroism (VCD) spectra of several chiral antiarrhythmic drugs (quinidine, flecainide, RAC 109, and propranolol) and chiral anti-inflammatory drugs (ibuprofen and naproxen) in the OH-, NH- and CH-stretching regions are reported. The absolute configurations of some of these drugs are identified by comparison to VCD spectra of similar molecules and by VCD intensity calculations on fragments of the drugs, utilizing either the locally distributed origin gauge (LDO) model or a priori vibronic coupling theory (VCT) methods. The most abundant conformations of propranolol, flecainide and RAC 109 in non-aqueous solution are also identified from the VCD spectra. This study demonstrates the utility of VCD in this spectral region for identification of solution conformation and absolute configuration for pharmaceuticals of moderate size. The conformations deduced from the VCD spectra provide insight into the stereospecific binding of the antiarrhythmic drugs.

Anti-Arrhythmia Agents↗
PubMed1998

Molecular confirmation of germ line mosaicism for a submicroscopic deletion of chromosome 22q11.

Submicroscopic deletions of chromosome 22q11 have been reported in a multiple anomaly syndrome variously labelled as velocardiofacial syndrome, conotruncal anomaly face syndrome, and Di George syndrome. Most 22q11 microdeletions occur sporadically, although in some cases the deletion may be transmitted. We describe two affected sibs with confirmed 22q11 deletions from unaffected parents who are not deleted. Haplotype analysis demonstrates that the deletion in the affected sibs has occurred on the same maternal chromosome 22. Furthermore, an unaffected sib was found to have inherited the same maternal haplotype at 22q11 in an undeleted form. This is the first molecular demonstration of germ line mosaicism for a microdeletion at chromosome 22q11 and highlights the need for caution in estimation of recurrence risks, even when constitutional deletions have been excluded on parental analysis.

Chromosome Deletion↗
PubMed1998

Multiple transcriptional elements in the avian type X collagen gene. Identification of Sp1 family proteins as regulators for high level expression in hypertrophic chondrocytes.

During the cartilage-to-bone transition, participating chondrocytes eventually undergo hypertrophy and are replaced by bone and marrow. Type X collagen is synthesized by chondrocytes specifically when they become hypertrophic, and this specificity is primarily regulated at the level of transcription. Previously, we demonstrated that a proximal promoter region from nucleotide -562 to +86 contained cis-acting elements that directed high level expression of a reporter gene in a cell-specific manner (Long, F., and Linsenmayer, T. F. (1995) J. Biol. Chem. 270, 31310-31314). In the present study, we have further dissected this region by generating a series of constructs and examining their expression in hypertrophic versus nonhypertrophic chondrocytes. Several positive and negative elements have been delineated within the proximal promoter region to mediate the regulation of transcription in hypertrophic chondrocytes. Most notably, a sequence from nucleotide -139 to +5 was sufficient to direct high level expression in this cell type. Electrophoresis mobility shift assay and supershift experiments identified within this sequence two 10-base pair noncanonical binding sites for Sp1 proteins. Mutations within the Sp1 binding sites either diminished or abolished the expression driven by the sequence from -139 to +5. These results indicate that the Sp1 proteins mediate the cell-specific expression of type X collagen.

Animals↗
PubMed1998

FISH and molecular study of autosomal supernumerary marker chromosomes excluding those derived from chromosomes 15 and 22: I. Results of 26 new cases.

The chromosomal origins and in some cases the molecular composition of 26 autosomal supernumerary marker chromosomes (SMC) were identified using combined fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) techniques. Fifteen were de novo, 4 maternally and 2 paternally transmitted and in 5 cases the parental origin is not known. Eleven cases were non-mosaic and fifteen cases had SMC cell lines ranging from 8-87%. Ten cases were ascertained prenatally, nine postnatally with abnormal phenotypes, three with poor reproductive histories and four co-incidentally. Five SMC were small rings from chromosomes 3, 6 (2 cases), 20 and 21; 8 were bisatellited from chromosomes 13/21 (4 cases), 14 (3 cases) and 14/22 (1 case). The remaining 13 appeared to be minutes comprising centromeric material only from chromosomes 1, 4, 12, 13/21 (2 cases), 14 (3 cases), 16 (2 cases), 19; 5/19, and a centric fusion involving 13 or 21 and 14. Euchromatin was detected in 9 out of 18 SMC tested with paints and/or PCR, and abnormal phenotypes were most commonly observed in patients with small ring shaped SMCs containing euchromatic sequences. Uniparental paternal isodisomy (UPD) for chromosome 6 was detected in one patient but was the only example of UPD for the normal homologues in association with an autosomal SMC in an overall total of 30 cases examined.

Chromosome Aberrations↗
PubMed1998

Type X collagen and other up-regulated components of the avian hypertrophic cartilage program.

Elucidating the cellular and molecular processes involved in growth and remodeling of skeletal elements is important for our understanding of congenital limb deformities. These processes can be advantageously studied in the epiphyseal growth zone, the region in which all of the increase in length of a developing long bone is achieved. Here, young chondrocytes divide, mature, become hypertrophic, and ultimately are removed. During cartilage hypertrophy, a number of changes occur, including the acquisition of synthesis of new components, the most studied being type X collagen. In this review, which is based largely on our own work, we will first examine the structure and properties of the type X collagen molecule. We then will describe the supramolecular forms into which the molecule becomes assembled within tissues, and how this changes its physical properties, such as thermal stability. Certain of these studies involve a novel, immunohistochemical approach that utilizes an antitype X collagen monoclonal antibody that detects the native conformation of the molecule. We describe the developmental acquisition of the molecule, and its transcriptional regulation as deduced by in vivo footprinting, transient transfection, and gel-shift assays. We provide evidence that the molecule has unique diffusion and regulatory properties that combine to alter the hypertrophic cartilage matrix. These conclusions are derived from an in vitro system in which exogenously added type X collagen moves rapidly through the cartilage matrix and subsequently produces certain changes mimicking ones that have been shown normally to occur in vivo. These include altering the cartilage collagen fibrils and effecting changes in proteoglycans. Last, we describe the subtractive hybridization, isolation, and characterization of other genes up-regulated during cartilage hypertrophy, with specific emphasis on one of these--transglutaminase.

Animals↗
PubMed1998

Regulation of growth region cartilage proliferation and differentiation by perichondrium.

Endochondral bone formation in vertebrates requires precise coordination between proliferation and differentiation of the participating chondrocytes. We examined the role of perichondrium in this process using an organ culture system of chicken embryonic tibiotarsi. A monoclonal antibody against chicken collagen type X, specifically expressed by hypertrophic chondrocytes, was utilized to monitor the terminal differentiation of chondrocytes. Proliferation of chondrocytes was examined by a BrdU-labeling procedure. The absence of perichondrium is correlated with an extended zone of cartilage expressing collagen type X, suggesting that the perichondrium regulates chondrocyte hypertrophy in a negative manner. Removal of perichondrium, in addition, resulted in an extended zone of chondrocytes incorporating BrdU, indicating that the perichondrium also negatively regulates the proliferation of chondrocytes. Partial removal of perichondrium from one side of the tibiotarsus led to expansion of both the collagen type X-positive domain and the BrdU-positive zone at the site of removal but not where the perichondrium remained intact. This suggests that both types of regulation by the perichondrium are local effects. Furthermore, addition of bovine parathyroid hormone (PTH) to perichondrium-free cultures reversed the expansion of the collagen type X-positive domain but not that of the proliferative zone. This suggests that the regulation of differentiation is dependent upon the PTH/PTHrP receptor and that the regulation of proliferation is likely independent of it. Taken together, these results are consistent with a model where perichondrium regulates both the exit of chondrocytes from the cell cycle, and their subsequent differentiation.

Animals↗