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Biomedical subjects

F Nasr

Publications and source records attributed to F Nasr.

At least 19 recordsLinked to original sources
PubMed2001

Arthritis in familial Mediterranean fever.

We studied the rheumatic and various clinical manifestations of familial Mediterranean fever (FMF) in Lebanon. A retrospective review was performed of the medical records of 74 FMF patients seen at the American University of Beirut Medical Centre (AUB-MC) from 1979 to 1996. We also reviewed the medical literature from 1968 to 2000 using MEDLINE and the key words "familial Mediterranean fever" and "arthritis". Arthritis was the presenting symptom in 12 cases (16.2%). Twenty-three patients (31%) had definite arthritis during the course of the disease that was monoarticular in 16 (70%), oligoarticular in six (26%), and polyarticular (rheumatoid-like) in one (4%). Arthritis of the large joints of the knees and ankles was the most frequent articular involvement. The arthritis was transient, monoarticular, nonerosive, and nondeforming in the majority of cases. Four patients (5.4%) had chronic arthritis, with one requiring total hip replacement. As in previous reports on arthritis of FMF, the majority of FMF patients studied in Lebanon had a transient monoarticular nonerosive and nondeforming type of arthritis affecting predominantly the large joints of the lower extremities.

Adolescent↗
PubMed2001

Ria1p (Ynl163c), a protein similar to elongation factors 2, is involved in the biogenesis of the 60S subunit of the ribosome in Saccharomyces cerevisiae.

RIA1 (YNL163c) is a quasi-essential gene that encodes a protein with strong similarities to elongation factors 2. Small C-terminal deletions in the protein lead to a severe growth defect. In the case of a 22-residue C-terminal deletion this can be suppressed by intragenic mutations in the RIA1 gene or dominant extragenic mutations in TIF6, which is thought to be involved in the biogenesis of the 60S subunit of the ribosome. The dominant TIF6 alleles can also suppress the phenotype associated with a complete deletion of the RIA1 gene. Depletion of Ria1p has a dramatic effect on the polysome profile: there is a severe reduction in the level of the 80S monosomes, an imbalance in the 40S/60S ratio, and halfmers appear. Dissociation of the monosomes and polysomes in the Ria1p depletion mutant revealed a specific reduction in the amount of 60S subunits. Localization experiments with HA-tagged derivatives of Ria1p did not detect any stable association of Ria1p with ribosome subunits, 80S monosomes or polysomes. Cell fractionation experiments show that Ria1p is found in both the cytoplasmic fraction and the nuclear fraction. Taken together, these data suggest that Ria1p is involved in the biogenesis of the 60S subunit of the ribosome.

Cloning, Organism↗
PubMed2001

Bms1p, a G-domain-containing protein, associates with Rcl1p and is required for 18S rRNA biogenesis in yeast.

Maturation of 18S rRNA and biogenesis of the 40S ribosomes in yeast requires a large number of trans-acting factors, including the U3 small nucleolar ribonucleoprotein (U3 snoRNP), and the recently characterized cyclase-like protein Rcl1p. U3 snoRNP is a key particle orchestrating early 35S rRNA cleavage events. A unique property of Rcl1p is that it specifically associates with U3 snoRNP, but this association appears to occur only at the level of nascent ribosomes and not with the U3 monoparticle. Here we report the characterization of Bms1p, a protein that associates with Rcl1p in multiple structures, including a specific complex sedimenting at around 10S. Like Rcl1p, Bms1p is an essential, evolutionarily conserved, nucleolar protein, and its depletion interferes with processing of the 35S pre-rRNA at sites A0, A1, and A2, and the formation of 40S subunits. The N-terminal domain of Bms1p has structural features found in regulatory GTPases and we demonstrate that mutations of amino acids implicated in GTP/GDP binding affect Bms1p activity in vivo. The results indicate that Bms1p may act as a molecular switch during maturation of the 40S ribosomal subunit in the nucleolus.

Amino Acid Sequence↗
PubMed2000

Cbk1p, a protein similar to the human myotonic dystrophy kinase, is essential for normal morphogenesis in Saccharomyces cerevisiae.

We have studied the CBK1 gene of Saccharomyces cerevisiae, which encodes a conserved protein kinase similar to the human myotonic dystrophy kinase. We have shown that the subcellular localization of the protein, Cbk1p, varies in a cell cycle-dependent manner. Three phenotypes are associated with the inactivation of the CBK1 gene: large aggregates of cells, round rather than ellipsoidal cells and a change from a bipolar to a random budding pattern. Two-hybrid and extragenic suppressor studies have linked Cbk1p with the transcription factor Ace2p, which is responsible for the transcription of chitinase. Cbk1p is necessary for the activation of Ace2p and we have shown that the aggregation phenotype is due to a lack of chitinase expression. The random budding pattern and the round cell phenotype of the CBK1 deletion strain show that in addition to its role in regulating chitinase expression via Ace2p, Cbk1p is essential for a wild-type morphological development of the cell.

Base Sequence↗
PubMed2000

Rcl1p, the yeast protein similar to the RNA 3'-phosphate cyclase, associates with U3 snoRNP and is required for 18S rRNA biogenesis.

RNA 3'-terminal phosphate cyclases are evolutionarily conserved enzymes catalysing conversion of the 3'-terminal phosphate in RNA to the 2',3'-cyclic phosphodiester. Their biological role remains unknown. The yeast Saccharomyces cerevisiae contains a gene encoding a protein with strong sequence similarity to the characterized cyclases from humans and Escherichia coli. The gene, named RCL1 (for RNA terminal phosphate cyclase like), is essential for growth, and its product, Rcl1p, is localized in the nucleolus. Depletion or inactivation of Rcl1p impairs pre-rRNA processing at sites A(0), A(1) and A(2), and leads to a strong decrease in 18S rRNA and 40S ribosomal subunit levels. Immunoprecipitations indicate that Rcl1p is specifically associated with the U3 snoRNP, although, based on gradient analyses, it is not its structural component. Most of Rcl1p sediments in association with the 70-80S pre-ribosomal particle and a 10S complex of unknown identity. Proteins similar to Rcl1p are encoded in genomes of all eukaryotes investigated and the mouse orthologue complements yeast strains depleted of Rcl1p. Possible functions of Rcl1p in pre-rRNA processing and its relationship to the RNA 3'-phosphate cyclase are discussed.

Alleles↗
PubMed2000

Characterization of the Saccharomyces cerevisiae cyclic nucleotide phosphodiesterase involved in the metabolism of ADP-ribose 1",2"-cyclic phosphate.

ADP-ribose 1",2"-cyclic phosphate (Appr>p) is produced in yeast and other eukaryotes as a consequence of tRNA splicing. This molecule is converted to ADP-ribose 1"-phosphate (Appr-1"p) by the action of the cyclic nucleotide phosphodiesterase (CPDase). Comparison of the previously cloned CPDase from Arabidopsis with proteins having related cyclic phosphodiesterase or RNA ligase activities revealed two histidine-containing tetrapeptides conserved in these enzyme families. Using the consensus phosphodiesterase signature, we have identified the yeast Saccharomyces cerevisiae open reading frame YGR247w as encoding CPDase. The bacterially expressed yeast protein, named Cpd1p, is able to hydrolyze Appr>p to Appr-1"p. Moreover, as with the previously characterized Arabidopsis and wheat CPDases, Cpd1p hydrolyzes nucleosides 2',3'-cyclic phosphates (N>p) to nucleosides 2'-phosphates. Apparent K (m)values for Appr>p, A>p, U>p, C>p and G>p are 0.37, 4.97, 8.91, 12.18 and 14.29 mM, respectively. Site-directed mutagenesis of individual amino acids within the two conserved tetrapeptides showed that H(40)and H(150)residues are essential for CPDase activity. Deletion analysis has indicated that the CPD1 gene is not important for cellular viability. Likewise, overexpression of Cpd1p had no effect on yeast growth. These results do not implicate an important role for Appr>p or Appr-1"p in yeast cells grown under standard laboratory conditions.

Adenosine Diphosphate Ribose↗
PubMed2000

Association of an odor with activation of olfactory bulb noradrenergic beta-receptors or locus coeruleus stimulation is sufficient to produce learned approach responses to that odor in neonatal rats.

These experiments examined the sufficiency of pairing an odor with either intrabulbar activation of noradrenergic beta-receptors or pharmacological stimulation of the locus coeruleus to support learned odor preferences in Postnatal Day 6-7 rat pups. The results showed that pups exposed to odor paired with beta-receptor activation limited to the olfactory bulb (isoproterenol, 50 microM) displayed a conditioned approach response on subsequent exposure to that odor. Furthermore, putative stimulation of the locus coeruleus (2 microM idazoxan or 2 mM acetylcholine) paired with odor produced a subsequent preference for that odor. The effects of locus coeruleus stimulation could be blocked by a pretraining injection of the beta-receptor antagonist propranolol (20 mg/kg). Together these results suggest that convergence of odor input with norepinephrine release from the locus coeruleus terminals within the olfactory bulb is sufficient to support olfactory learning.

Adrenergic beta-Agonists↗
PubMed1999

Deletions and losses in chromosomes 5 or 7 in adult acute lymphocytic leukemia: incidence, associations and implications.

Deletions or losses in chromosomes 5 or 7 are recurrent non-random abnormalities in acute myeloid leukemia (AML), and are associated with prior exposure to carcinogens or leukemogenic agents, and with poor prognosis. Their occurrence and significance in adult acute lymphocytic leukemia (ALL) is not well described. The aim of the study was to evaluate the incidence, associations and implications of chromosome 5 or 7 abnormalities in adult ALL. Patients with newly diagnosed ALL referred to MD Anderson Cancer Center between 1980 and 1996 were analyzed. Characteristics and outcome of patients with or without chromosome 5 or 7 abnormalities were compared by standard statistical methods. Thirty-one of 468 patients (6.6%) had chromosome 5 or 7 abnormalities. Loss of chromosome 5 occurred in six cases, three of them had both chromosome 5 and 7 abnormalities. Deletion or loss of chromosome 7 occurred as a single abnormality in three patients; in 28 patients it was associated with other abnormalities. The most significant cytogenetic association was with the Philadelphia chromosome (Ph) abnormality occurring in nine patients (29%). Compared with patients without the abnormalities, patients with chromosome 5 or 7 abnormalities tended to express CD34 more frequently (74% vs 54% P = 0.07), to be older (age >60 years 29% vs 18% P = 0.14), and to be associated with Ph (29% vs 11% P = 0.004). With therapy, the complete response (CR) rate with chromosome 5 or 7 abnormalities was lower (64% vs 79% P = 0.038) but the survival rate was similar (3-year survival rate 32% vs 36% P = 0.14). When the 22 patients without Ph were considered separately, the CR and survival rates were similar among patients with or without chromosome 5 or 7 abnormalities. Abnormalities in chromosome 5 or 7 are not specific for AML, and may occur in ALL. Unlike in AML, chromosome 5 or 7 abnormalities in ALL were not predictive of worse prognosis, which is accounted for mostly by the association with Ph.

Adolescent↗
PubMed1999

Systemic lupus erythematosus in Lebanon.

The present study describes the clinical characteristics of patients with systemic lupus erythematosus (SLE) from the American University of Beirut Medical Center (AUBMC), one of the largest teaching hospitals in Lebanon. This is a retrospective chart review of 100 SLE patients seen over a 20 y period. There were 86 females and 14 males, with a median age of 26 y. 85 patients were Lebanese and 15 patients were Palestinians. The main clinical features were arthritis and/or arthralgias seen in 95% of our patients, followed by malar rash (52%), and renal involvement (50%). Of the hematological manifestations, thrombocytopenia was most commonly seen in 33% of patients, followed by leucopenia in 17% and hemolytic anemia in 10% Oral ulcers and serositis were both seen in 40% of patients. Less frequent manifestations included discoid lupus (19%), neuropsychiatric manifestations (19%), and photosensitivity (16%). Antinuclear antibodies were detected in 87% of patients, whereas anti-DNA antibodies were seen in 50% of cases. 25 patients (25%) had a false-positive VDRL. A comparison between our findings and 3 other Arab SLE groups revealed a higher incidence of oral ulcers, discoid lupus, articular manifestations, thrombocytopenia and false-positive VDRL, and a lower incidence of photosensitivity, leucopenia, neuropsychiatric manifestations, and anti-DNA antibodies.

Adult↗
PubMed1998

VIP (etoposide, ifosfamide and cisplatinum) as a salvage intensification program in relapsed or refractory Hodgkin's disease.

Forty-two patients with refractory (15 patients) or relapsed (27 patients) Hodgkin's disease (HD) were included in a prospective single center study evaluating the efficacy of a regimen VIP combining etoposide 75 mg/m2/day days 1-5, ifosfamide 1.2 g/m2/day days 1-5 and cisplatinum 20 mg/m2/day days 1-5, one course every 4 weeks as salvage therapy in patients with refractory or relapsed Hodgkin's disease, potentially eligible for high-dose chemotherapy with reinjection of hematopoietic stem cells (HSC). If patients were considered chemosensitive after two courses of VIP, high-dose chemotherapy followed by the reinjection of HSC was planned. After two courses of VIP, 67% achieved an objective response including 38% complete responses. Overall, 28 patients went on to high-dose therapy with reinjection of HSC, and 46% of grafted patients are in a sustained complete remission. When the overall patient population is considered, 33% are in complete remission (CR) with a median follow-up of 37 months. A CR of less than 12 months and refractory disease were associated with a poor survival. These results showed that the VIP regimen is effective in relapsed or refractory HD and allows high-dose therapy to be given in the case of most responding patients. However, results in patients with refractory disease or a first complete remission of less than 12 months need to be further improved.

Adolescent↗
PubMed1998

Osteomalacia secondary to celiac disease, primary hyperparathyroidism, and Graves' disease.

Primary hyperparathyroidism is seldom associated with other autoimmune disorders. The presence of normocalcemia in primary hyperparathyroidism should prompt the physician to look for vitamin D deficiency. This observation concerns a 34-year-old vegetarian woman with combined primary hyperparathyroidism, Graves' disease, and celiac disease. The patient presented with severe bone deformities; she was unable to walk, and had severe muscular weakness and weight loss. Biochemical findings revealed severe hyperparathyroidism with normocalcemia, hypophosphatemia, very low urinary calcium, and low 25-hydroxy vitamin D level. Thyroid tests showed hyperthyroidism with positive thyroid receptor antibodies, confirming the presence of Graves' disease. Positive antigliadin and antireticulin antibodies and complete villous atrophy on duodenal biopsy established the presence of celiac disease. The patient underwent a near-total thyroidectomy, with the removal of a parathyroid adenoma. To our knowledge, this observation is the first finding of an association between celiac disease, Graves' disease, and primary hyperparathyroidism. It emphasizes the need to rule out intestinal malabsorption in the case of normocalcemic hyperparathyroidism.

Adenoma↗
PubMed1997

The nucleotide sequence of Saccharomyces cerevisiae chromosome XIV and its evolutionary implications.

In 1992 we started assembling an ordered library of cosmid clones from chromosome XIV of the yeast Saccharomyces cerevisiae. At that time, only 49 genes were known to be located on this chromosome and we estimated that 80% to 90% of its genes were yet to be discovered. In 1993, a team of 20 European laboratories began the systematic sequence analysis of chromosome XIV. The completed and intensively checked final sequence of 784,328 base pairs was released in April, 1996. Substantial parts had been published before or had previously been made available on request. The sequence contained 419 known or presumptive protein-coding genes, including two pseudogenes and three retrotransposons, 14 tRNA genes, and three small nuclear RNA genes. For 116 (30%) protein-coding sequences, one or more structural homologues were identified elsewhere in the yeast genome. Half of them belong to duplicated groups of 6-14 loosely linked genes, in most cases with conserved gene order and orientation (relaxed interchromosomal synteny). We have considered the possible evolutionary origins of this unexpected feature of yeast genome organization.

Base Sequence↗
PubMed1997

Translocation t(4;11)(q21;q23) and MLL gene rearrangement in acute lymphoblastic leukemia secondary to anti topoisomerase II anticancer agents.

Secondary therapy-related, acute lymphoblastic leukemia (S-ALL) is less common than its myeloblastic counterpart. S-ALL with MLL gene rearrangements have only been reported on six previous occasions. Only three of these had t(4;11)(q21;23) S-ALL with MLL-AF4 fusion transcript has only been reported in one earlier case. In this report a rare case of S-ALL with MLL-AF4 transcript is described in a 36 year old woman treated for breast carcinoma with chemotherapy which included the topoisomerase II inhibitor, VP-16. The precise incidence of MLL gene rearrangement in S-ALL still remains to be clarified.

Adult↗
PubMed1996

The sequence of 36.8 kb from the left arm of chromosome XIV reveals 24 complete open reading frames: 18 correspond to new genes, one of which encodes a protein similar to the human myotonic dystrophy kinase.

We have determined the complete nucleotide sequence of a 36.8 kb segment from the left arm of chromosome XIV carried by the cosmid 14-11. The sequence encodes the 5' coding region of the PSD1 gene, the 3' coding region of an unknown gene and 24 complete open reading frames, of which 18 correspond to new genes and six (SKO1, SCL41A, YGP1, YCK2, RPC31 and MFA2) have been sequenced previously. Of the 24 new genes, five show significant similarities to sequences present in the databanks. These include elongation factors 2 and the human myotonic dystrophy kinase.

Amino Acid Sequence↗
PubMed1996

The sequence of 12.8 kb from the left arm of chromosome XIV reveals a sigma element, a pro-tRNA and six complete open reading frames, one of which encodes a protein similar to the human leukotriene A4 hydrolase.

We have determined the nucleotide sequence of a 12.8 kb fragment from the left arm of chromosome XIV carried by the cosmid 14-16d. An analysis of the sequence reveals the presence of a sigma element, a pro-tRNA gene and eight open reading frames, six of which are complete. All of the eight open reading frames correspond to new genes. Of the eight new genes, two show strong similarities to a pair of new genes from chromosome IX, suggesting an ancestral duplication, and one gene encodes a protein similar to mammalian leukotriene A4 hydrolase.

Amino Acid Sequence↗
PubMed1996

High incidence of secondary myelodysplastic syndromes following PROMACE-MOPP and involved field radiotherapy for localized gastric non-Hodgkin's lymphomas.

The incidence of secondary myelodysplastic syndromes (MDS) are rarely reported in an homogeneous patient population treated for non-Hodgkin's lymphoma (NHL). Less than 10 per cent of secondary MDS are usually observed in patients treated for Hodgkin's disease and NHL. Data on the incidence of secondary MDS induced by modern chemotherapeutic regimens is needed. Between January 1985 and January 1989, 20 patients with localized gastric non-Hodgkin's lymphomas (stage I to IIE) were prospectively treated at the Institut Gustave-Roussy with PROMACE-MOPP multi-agent chemotherapy and involved-field irradiation. The mean age was 54 years (range 23 to 69 years). Seven patients died while on therapy or relapsed 2 to 28 months after therapy. Thirteen patients were followed up for at least 5 years. Three of the 13 long-term survivors (23 per cent) developed a myelodysplastic syndrome (MDS) 48, 62 and 72 months after the end of therapy. Cytogenetic analysis was performed in two cases and showed-7 and 18q- in one case, t(9;21)(q13;q22), 21q+, i17q in the other case. PROMACE-MOPP plus radiotherapy should not be recommended in patients with localized gastric non-Hodgkin's lymphoma due to the high risk of developing secondary myelodysplastic syndromes.

Adult↗