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M Sayed

Publications and source records attributed to M Sayed.

15 recordsLinked to original sources
PubMed2001

Identification of the autophosphorylation sites and characterization of their effects in the protein kinase DYRK1A.

Protein kinases of the DYRK ('dual-specificity tyrosine-regulated kinase') family are characterized by a conserved Tyr-Xaa-Tyr motif (Tyr-319-Tyr-321) in a position exactly corresponding to the activation motif of the mitogen-activated protein kinase (MAP kinase) family (Thr-Xaa-Tyr). In a molecular model of the catalytic domain of DYRK1A, the orientation of phosphorylated Tyr-321 is strikingly similar to that of Tyr-185 in the known structure of the activated MAP kinase, extracellular-signal-regulated kinase 2. Consistent with our model, substitution of Tyr-321 but not of Tyr-319 by phenylalanine markedly reduced the enzymic activity of recombinant DYRK1A expressed in either Escherichia coli or mammalian cells. Direct identification of phosphorylated residues by tandem MS confirmed that Tyr-321, but not Tyr-319, was phosphorylated. When expressed in COS-7 cells, DYRK1A was found to be fully phosphorylated on Tyr-321. A catalytically inactive mutant of DYRK1A contained no detectable phosphotyrosine, indicating that Tyr-321 is autophosphorylated by DYRK1A. MS identified Tyr-111 and Ser-97 as additional autophosphorylation sites in the non-catalytic N-terminal domain of bacterially expressed DYRK1A. Enzymic activity was not affected in the DYRK1A-Y111F mutant. The present experimental data and the molecular model indicate that the activity of DYRK1A is dependent on the autophosphorylation of a conserved tyrosine residue in the activation loop.

Animals↗
PubMed2001

Protein kinase CK2 is involved in G2 arrest and apoptosis following spindle damage in epithelial cells.

p53 undergoes phosphorylation on several residues in response to cellular stresses that include UV and ionizing radiation, however the influence of spindle damage on this parameter is relatively unclear. Consequently, the effect of nocodazole on serine 392 phosphorylation was examined in two epithelial cell lines. We show that this process is dependent upon the stepwise activation of p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase casein kinase 2 (CK2). Furthermore, this activation correlated with the biochemical regulation of the maturation-promoting factor (MPF, cdc2/cyclin B), as both DRB and antisense depletion of CK2, as well as SB203580 were associated with an inhibition of its activation in response to nocodazole. Strikingly, when the cell cycle characteristics of nocodazole treated cells were examined, we observed that depletion or inhibition of the catalytic subunit of CK2, in the presence of microtubule inhibitors, resulted in a compromise of the G2 arrest (spindle checkpoint). Furthermore, CK2-depleted, nocodazole treated cells demonstrated a dramatic reduction in the apoptotic cell fraction, confirming that these cells had been endowed with oncogenic properties. These changes were observed in both HeLa cells and HCT116 cells. We also show that this effect is dependent on the presence of functional wild-type p53, as this phenomenon is not apparent in HCT116 p53(-/-) cells. Collectively, our results indicate two novel roles for CK2 in the spindle checkpoint arrest, in concert with p53. Firstly, to maintain increased cyclinB/cdc2 kinase activity, as a component of G2 arrest, and secondly, a role in p53-mediated apoptosis. These findings may have implications for an improved understanding of abnormalities of the spindle checkpoint in human cancers, which is a prerequisite for defining future therapies.

Apoptosis↗
PubMed2001

A selective phosphodiesterase IV inhibitor, rolipram blocks both withdrawal behavioral manifestations, and c-Fos protein expression in morphine dependent mice.

We investigated the effect of rolipram, a selective phosphodiesterase IV inhibitor, on morphine dependence in mice. The withdrawal manifestations were significantly reduced in mice that were treated with rolipram in combination with morphine repeatedly, compared to the mice treated with morphine and saline. Immunohistochemical study of c-Fos protein revealed a significant increase in the protein expression, 1 h after naloxone induced withdrawal manifestations. A combination of rolipram and morphine treatment for 5 days prevented the increase of c-Fos protein expression. Acute rolipram treatment prior to the naloxone challenge had no effect. Repeated treatment with rolipram itself had no effect either on behavior, or on c-Fos protein expression. These results suggest that chronic rolipram treatment in combination with morphine in mice will abolish the development of morphine dependence and the expression of c-Fos protein induced by naloxone challenge.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2001

How was this story told in the mother tongue? An integrative perspective.

Most of the psychoanalytic literature on the mother tongue has focused on the clinical therapeutic encounter. The authors applied findings from therapy research using the Thematic Apperception Test (TAT) to tease out differences and similarities in how stories are told in the mother tongue versus the acquired language. This projective test provides a rich medium to explore the individual's inner world, fantasies, thoughts, wishes, sense of self, and self-in-relation-to-other via a narrative that is spontaneously produced in response to standardized stimuli. The TAT was administered to four participants in both the mother tongue and the acquired language. The narratives were then analyzed using two different rating systems. Differences in sense of self, self-in-relation-to-other, and level of pathology were identified using one participant's narratives. Although no global generalizations can be made from one study, the authors suggest that people tell their story differently when speaking in the mother tongue versus the acquired language.

Adult↗
PubMed2001

[Unusual radiologic signs of bone echinococcosis in children].

The authors report 2 cases of 2 children aging 11 and 12-years-old presenting hydatitosis in the upper extremity of 2 long bones femur and tibia. In 2 cases, radiological appearances were atypical. In the femur, plain radiographs revealed multiple lucencies, irregular, located in the superior extremity with a periostal reaction. The CT scan confirmed these data and showed a cortical rupture, extension to soft tissue with contrast enhancement. In the tibia, plain radiographys showed delimitated lucencies, confluent with a rim condensation in the proximal epiphyseal-metaphyseal area. Echography and CT are helpful when radiological appearances are unusual.

Biopsy↗
PubMed2000

Stress-induced activation of protein kinase CK2 by direct interaction with p38 mitogen-activated protein kinase.

Protein kinase CK2 has been implicated in the regulation of a wide range of proteins that are important in cell proliferation and differentiation. Here we demonstrate that the stress signaling agents anisomycin, arsenite, and tumor necrosis factor-alpha stimulate the specific enzyme activity of CK2 in the human cervical carcinoma HeLa cells by up to 8-fold, and this could be blocked by the p38 MAP kinase inhibitor SB203580. We show that p38alpha MAP kinase, in a phosphorylation-dependent manner, can directly interact with the alpha and beta subunits of CK2 to activate the holoenzyme through what appears to be an allosteric mechanism. Furthermore, we demonstrate that anisomycin- and tumor necrosis factor-alpha-induced phosphorylation of p53 at Ser-392, which is important for the transcriptional activity of this growth suppressor protein, requires p38 MAP kinase and CK2 activities.

Amino Acid Sequence↗
PubMed2000

Cognitive dysfunction in obsessive-compulsive disorder.

OBJECTIVE: Assessment of cognitive functions among obsessive-compulsive disorder (OCD) patients would help in understanding the neurobiology and brain areas involved in that disorder. The objective of this work was to study the cognitive dysfunction in OCD patients and to identify its correlation with both the clinical picture and the severity of the disorder. METHOD: Neuropsychological and electrophysiological event-related potentials were tested in 30 OCD patients and compared with 30 normal volunteers of a matched gender, age and education. RESULTS: Results showed a defective visuospatial recognition, which worsens with chronicity, deteriorated set-shifting abilities, overfocused attention to irrelevant stimuli and delayed selective attention to relevant tasks. Mild cases showed better selective attention than severe cases. Obsessive cases had a defective visual memory, while compulsive cases had delayed perception of task relevant stimuli. Mixed cases showed disturbed information-processing both early and late. CONCLUSION: OCD patients have a characteristic pattern of cognitive dysfunction that differs among patients of varied severity, chronicity and symptom type. We suggest a striatofrontoparietal neural pathophysiology. OCD seems to be a heterogeneous disorder, both clinically and pathophysiologically.

Adolescent↗
PubMed1999

Characterization of an activated ribosomal S6 kinase variant from maturing sea star oocytes: association with phosphatase 2A and substrate specificity.

Two ribosomal protein S6 kinases (i.e., pp52(S6K) and pp70(S6K)) of the p70 S6 kinase family were markedly activated during meiotic maturation of Pisaster ochraceus sea star oocytes. A rapid protocol was developed for the purification from the oocyte cytosol of pp52(S6K) by approximately 50,000-fold with a specific enzyme activity of 1.6 micromol per min per mg. The purified enzyme apparently featured the N- and C-terminal regions of pp70(S6K) as it immunoreacted with antibodies directed to peptides patterned after these amino acid sequences in mammalian pp70(S6K). pp52(S6K) was inhibited by fluoride (IC(50) approximately 60 mM), but was relatively insensitive to beta-glycerolphosphate, EGTA, dithiothreitol, spermine, heparin, NaCl, and metal ions such as Mn(2+), Zn(2+), and Ca(2+). The consensus sequence for substrate phosphorylation was determined to be RXXSXR, which was partially distinct from mammalian p70(S6K) in its requirement for an amino-terminal arginine. Phosphorylation of ribosomal protein S6 by p52(S6K) occurred exclusively on serine on at least five tryptic peptides. Inhibition of sea star p52(S6K) phosphotransferase activity after treatment with protein serine/threonine phosphatases confirmed that p52(S6K) was still regulated by phosphorylation. The sea star S6 kinase was purified to near homogeneity with the regulatory and catalytic subunits of protein-serine phosphatase 2A and the heat shock protein 60. The association of an S6 kinase with phosphatase 2A was confirmed by coimmunoprecipitation of S6 kinase activity with phosphatase 2A-specific antibodies. The purified S6 kinase and the sea star oocyte system will be useful for analysis of upstream and downstream signaling events that lead to phosphorylation of the S6 protein and other targets.

Amino Acid Sequence↗
PubMed1998

Staging the axilla in breast cancer: an audit of lymph-node retrieval in one U.K. regional centre.

AIMS: Many surgeons undertake a level 1 axillary dissection in patients with invasive breast cancer. This dissection yields a variable number of lymph nodes for histological study. In this study, we report the consequences of this policy for staging of the axilla. METHODS: Between January 1995 and December 1995, 236 patients with a diagnosis of invasive breast cancer underwent axillary surgery. RESULTS: A median of eight nodes was identified (range 0-30). In only 11 patients less than four nodes were identified. An increase in the number of nodes harvested was associated with a higher proportion of node-positive patients and a higher number of metastatic nodes identified. CONCLUSIONS: We concluded that a standardized approach to axillary dissection consistently yields an adequate sample of lymph nodes for staging purposes. Most importantly, larger node samples yield higher detection rates for metastasis. This has a significant bearing on patient selection for adjuvant chemotherapy when compared with more limited sampling practices, including solitary sentinel node detection and biopsy.

Adult↗
PubMed1996

Agenesis of corpus callosum, hypertrophic pyloric stenosis and Hirschsprung disease: coincidence or common etiology?

This article reports a full-term infant with Hirschsprung disease (HD) who was diagnosed to have hypertrophic pyloric stenosis (HPS) and agenesis of corpus callosum (ACC). Pyloric stenosis is known to be associated with HD. To our knowledge, the combination of Hirschsprung disease, hypertrophic pyloric stenosis and agenesis of corpus callosum has not been reported previously. We believe these three conditions are due to an underlying pathophysiologic mechanism.

Abnormalities, Multiple↗
PubMed1991

Clinicoradiological diagnosis of benign osteoblastoma of the spine in children.

Three cases of benign osteoblastoma of the spine in children are reported, diagnosed on the basis of clinicoradiological findings and confirmed at surgery and by histopathology. The authors feel that in all cases of painful scoliosis and painful torticollis, a careful search should be made for any suspicious area of sclerosis, especially in the posterior elements of the vertebrae, and all the positive or suspected cases should undergo nuclear bone scanning. All patients whose bone scan is positive should be subjected to computed tomography for differential diagnosis between osteoid osteoma and benign osteoblastoma.

Adolescent↗
PubMed1988

Schistosomiasis and sarcoma of the urinary bladder.

A young male patient with schistosomiasis and sarcoma of the urinary bladder is presented. Total cystectomy followed by radiotherapy was performed. The gross appearance, microscopic findings of the tumor and an outline of the disease are discussed.

Adult↗
PubMed1985

Congenital absence of the mammary gland.

Tc-99m pertechnetate is known for its uptake and excretion by the mammary gland. Generally, lactating women are not advised to have any radioisotopic studies. If it is necessary to have one, it is recommended that they do not breast-feed their children for at least 24 hours. Congenital absence of the mammary gland is a rare condition. This case was accidently discovered. Nuclear medicine physicians should be aware of the value of clinical examination of patients, and that not every absent or asymmetric breast shadow is due to surgical resection.

Adult↗
PubMedDate not supplied

Protein-protein interactions in receptor activation and intracellular signalling.

We review here signalling complexes that we have defined using X-ray analysis in our laboratory. They include growth factors and their receptors: nerve growth factor (NGF) and its hetero-hexameric 7S NGF storage complex, hepatocyte growth factor/scatter factor (HGF/SF) NK1 dimers and fibroblast growth factor (FGF1) in complex with its receptor (FGFR2) ectodomain and heparin. We also review our recent structural studies on intracellular signalling complexes, focusing on phosducin transducin GPry, CK2 protein kinase and its complexes, and the cyclin D-dependent kinase, Cdk6, bound to the cell cycle inhibitor p19INK4d. Comparing the structures of these complexes with others we show that the surface area buried in signalling interactions does not always give a good indication of the strength of the interactions. We show that conformational changes are often important in complexes with intermediate buried surface areas of 1500 to 2000 A2, such as Cdk6INK4 interactions. Some interactions involve recognition of continuous epitopes, where there is no necessity for a tertiary structure and very often the binding conformation is induced during the process of interaction, for example phosducin binding to the betagamma subunits (Gtbetagamma) of the heterotrimeric G protein transducin.

Animals↗