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M Arif

Publications and source records attributed to M Arif.

At least 19 recordsLinked to original sources
PubMed2001

Technetium-99m direct radiolabeling of lanreotide: a somatostatin analog.

Lanreotide, a synthetic octapeptide analog of a native hormone somatostatin, was labeled with a commonly available, inexpensive radionuclide 99mTc. Labeling was accomplished by reduction of the cysteine bridge, which provided sulfhydryl groups for chelation with 99mTc. Stannous chloride was used as reducing agent, while tartrate acted as transchelating agent. Lanreotide (100 microg), stannous chloride dihydrate (100 microg) and tartaric acid (64 microg) were dissolved in acetate/acetic acid buffer (pH 2.8). After overnight (approximately 18 h) incubation, approximately 444 MBq (12 mCi) 99mTc was added and kept in boiling water for 30 min. More than 97% labeling efficiency was confirmed by RP-HPLC, ITLC-SG and C18 cartridge analysis. Radiolabeling results in one major peak when analyzed by reverse-phase HPLC. The stability of the 99mTc-peptide bond was evaluated by cysteine challenge studies.

Chromatography, High Pressure Liquid↗
PubMed2000

Transposition of duplicated chromosomal segment involving fused BCR-ABL gene or ABL oncogene alone in chronic myelocytic leukemia and Ph chromosome-positive acute leukemia with complex karyotypes.

Thirty-six patients with chronic myelocytic leukemia (CML) in the blastic phase were examined by fluorescence in situ hybridization to clarify the mechanisms of progression of the disease. Two of 19 CML patients in the blastic phase (10.5%) had an extra fused BCR-ABL gene on structurally complex chromosome aberrations in addition to the Ph chromosome. Another patient had an extra ABL oncogene on the end of a deleted chromosome, resulting in three copies of the ABL oncogene. These three patients showed additional chromosome aberrations, such as der(12), der(15), and der(18), which differ from the standard karyotypic evolution in the blastic phase. Amplification of the fused BCR-ABL gene or the ABL oncogene seemed to be induced by transposition. These segmental transpositions suggest that these regions have high genetic instability possibly leading to blastic transformation.

Chromosome Aberrations↗
PubMed1999

Iterative manual control model of human operator.

In this paper, we present an iterative manual control model of a human operator performing some repetitive task. Various aspects of the model are discussed in detail. Experiments have been done to study the human capability to perform the tasks by learning iteratively. Results of the experiments show the ability of the human operator to perform the tracking of a desired trajectory for some unknown non-linear system with quite reasonable accuracy during the iteration process. It is concluded that the human operator performs the repetitive task by modifying his control action using error and error rate in each iteration. During the modification, the human operator assigns different weights to the error and error rate in each iteration. These results can be implemented in designing more efficient iterative learning control algorithms.

Adenosine Diphosphate↗
PubMed1999

Seroepidemiology of hepatitis B virus infection in Saudi children 8 years after a mass hepatitis B vaccination programme.

OBJECTIVES: On October 1 1989, a programme was begun in Saudi Arabia in which the HBV vaccine was added as the 'seventh' primary immunogen of the Extended Programme of Immunization (EPI). In 1990, another programme was launched by the Ministry of Health to vaccinate all school children. Eight years after this mass vaccination programme, the efficacy of HBV vaccine was evaluated in a community-based study. METHODS: A community-based study was carried out in Saudi children in urban and rural areas, covering all the regions of Saudi Arabia. After informed consent, blood samples were obtained and tested for HBV markers. RESULTS: Among 4791 vaccinated Saudi children aged 1-12 years, only 15 were found to be HbsAg-positive (0.31%). HbsAg-positivity was 0.16% in children vaccinated at birth compared with 0.7% in those vaccinated at school entry. The overall HbsAg carrier rate dropped from 6.7% in 1989 to 0.3% in 1997 (P<0.00001). Similarly, there was a significant reduction in the prevalence of anti-HBc from 4.2% in 1989 to 0.46% in 1997 (P<0.00001). The overall seroconversion rate to HB vaccine among 4087 Saudi children up to 12 years of age was about 77%. Seroconversion rate in those vaccinated at birth was 77% compared with 71% in those vaccinated at school entry. After 8 years of receiving the third vaccine dose, close to 65% of the children had an anti-HBs titre of more than 10 IU/l compared with about 28% who had an anti-HBs titre of more than 100 IU/l after the same period. CONCLUSION: The result of this study demonstrates the tremendous impact of the mass HB vaccination programme on the seroepidemiology of HBV infection in Saudi Arabia. The ultimate goal of preventing HBV-related chronic liver disease and hepatocellular carcinoma in Saudi Arabia is foreseeable in the near future.

Child↗
PubMed1999

Detection of translocation 8;21 on interphase cells from acute myelocytic leukemia by fluorescence in situ hybridization and its clinical application.

To detect a translocation (8;21)(q22;q22) in interphase cells by fluorescence in situ hybridization (FISH), we investigated three probe combinations: single-color hybridization with two cosmid probes (cY8 and cY3), single-color hybridization with four cosmid probes (cY8, cY3, cY107, and cYR4), and dual-color hybridization with two cosmid probes (cY107 and cYR4) from the AML1 gene flanking or overlapping the breakpoint region. Over 95% of nuclei gave sufficient signals in all three probe combinations, and the detection rates were not statistically different among them. Among 18 patients examined at diagnosis, 12 with t(8;21) were also monitored for the number of residual leukemic cells after chemotherapy or bone marrow transplantation (BMT). There were some discrepancies between morphology and genetic (especially FISH) results at partial, or even complete remission. As leukemic cells with t(8;21) can maturate, morphological assessment alone is insufficient to evaluate the residual leukemic cells. Interphase FISH provided more precise information about the clinical status of patients with an 8;21 translocation after treatment.

Adult↗
PubMed1999

Interphase fluorescence in situ hybridization overcomes pitfalls of G-banding analysis with special reference to underestimation of chromosomal aberration rates.

Fluorescence in situ hybridization (FISH) is suitable for detecting different types of chromosome aberrations on interphase nuclei even in specimens with no or few chromosome metaphases. However, it is not known why FISH is superior to conventional G-banding analysis. The sensitivity of interphase FISH was compared to that of G-banding analysis in 288 leukemia/lymphoma patients for 10 different types of chromosome aberrations: t(9;22) (M- and m-BCR), t(8;21), 11q23 abnormalities, t(15;17), del(5)/-5, del(13)/-13, +8, -7, and +12. The results revealed that t(15;17) positive cells could not proliferate well in culture, leading to underestimation of abnormality by G-banding. Monosomy 7 in acute myelocytic leukemia (AML) and myelodysplastic syndrome (MDS) as well as trisomy 12 and deletion chromosome 13 in chronic lymphocytic leukemias (CLL) were also severely underestimated by G-banding. On the other hand, no discrepancies were observed in t(8;21), t(9;22), translations involving 11q23, or in trisomy 8. These findings indicate the superiority of interphase FISH over conventional cytogenetics for detecting chromosome abnormalities in small clones, especially for monosomy 7 or (15;17) translocations.

Chromosome Aberrations↗
PubMed1999

Determination of natural radioactivity in building materials used in the Rawalpindi/Islamabad area by gamma-ray spectrometry and instrumental neutron activation analysis.

Samples of sand and manufactured building materials collected from the Rawalpindi/Islamabad area have been analyzed for the primordial natural radionuclides 238U, 232Th and 40K using gamma-ray spectrometry. The uranium and thorium contents have also been determined by instrumental neutron activation analysis (INAA). The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The comparison shows that, of the nine samples analyzed, only the three brick samples have higher activities than the world averages for soil. The specific activities in these materials, having a radium equivalent activity of less than 370 Bq kg-1, when evaluated for radiological effects show that all materials meet the external gamma-ray dose limitation of 1.5 mSv y-1. The gamma-spectrometric and INAA techniques complemented each other well in this study.

Calibration↗
PubMed1999

Frequent allelic loss of the RB, D13S319 and D13S25 locus in myeloid malignancies with deletion/translocation at 13q14 of chromosome 13, but not in lymphoid malignancies.

In order to identify a commonly deleted region of 13q14 on chromosome 13, we performed fluorescence in situ hybridization (FISH) on 17 patients with myeloid malignancies and 12 patients with lymphoid leukemia/lymphoma who exhibited either deletion or translocation at 13q14. Three cosmid probes (RB, D13S319 and D13S25) hybridizing to sequences on 13q14 were used. Fourteen of the 17 patients with myeloid malignancies (82.4%) exhibited allelic loss at the RB, D13S319 and D13S25 locus, whereas only three of the 12 patients with lymphoid malignancies (25.0%) exhibited loss within these loci. These three patients had chronic lymphocytic leukemia (CLL). Six, two and one of the remaining nine lymphoid leukemia/lymphoma patients had breakpoints centromeric to the RB gene, telomeric to D13S25 and within the D13S319 locus, respectively. A high frequency of allelic loss was found using these probes in patients with myeloid malignancies, compared to in patients with leukemia in the lymphoid origin, except CLL patients. These results indicate that loss of the RB gene itself or a region between RB and D13S319, which includes commonly deleted loci, may play an important role in myeloid leukemogenesis.

Adult↗
PubMed1999

Human learning characteristics in the tracking tasks of iterative nature.

In this paper, human learning characteristics in the tracking tasks of iterative nature are investigated. Various linear and nonlinear systems are used as plant, and a human operator has to generate the proper control inputs to force these systems in tracking the desired trajectory. The learning behaviour of the human operator in modifying his control actions is studied and it is observed that the human operator can improve his performance quite efficiently despite the unavailability of any information about the system or the desired trajectories. It is concluded from the experiments that the human operator not only use the information that is directly available to him (error in this case), but also extracts some useful information (e.g. error rate) that he feels is necessary to generate a good control action. The limitation of the human performance is studied in frequency domain, and the performance of the human operator against the frequency bandwidth of error and error rate signals are highlighted. Analysis of the results revealed that a human operator gives more importance to the error rate in generating his control actions and, accordingly, it is observed that his limitation in term of performance is more sensitive to the frequency bandwidth of the error rate as compared to the error. The human operator cannot improve his performance once the frequency components of the error or error rates shift to the higher frequencies, say above 1.0 Hz.

Adult↗
PubMed1998

Fine-needle aspiration cytology of primary Kaposi's sarcoma of lymph nodes in an immunocompetent man.

This case report describes the fine-needle aspiration (FNA) findings of primary lymphadenopathic Kaposi's sarcoma (KS) in a 44-year-old African heterosexual male who is immunocompetent and has no clinical or serological evidence of the acquired immunodeficiency syndrome (AIDS) or the endemic form of KS. The cytological findings emphasize the role of FNA in the diagnosis of KS and draw the attention to the fact that a diagnosis of KS in an African man is not synonymous with the diagnosis of AIDS or endemic/African KS. A description of other spindle cell intranodal lesions which may mimick KS is given with a discussion of the differential diagnoses that should be considered in such cases by the cytopathologist.

Adult↗
PubMed1998

Isodicentric chromosome 21: a novel aberration in acute myeloid leukemia.

We present here a 78-year-old female patient with acute myeloid leukemia (AML), French-American-British classification M2, exhibiting isodicentric chromosome 21, idic(21)(q22), at the time of diagnosis. The patient had three idic(21)(q22), besides the del(5)(q13q32), add(21)(q22), dic(21;22) (q22;q13), and +22. Fluorescence in situ hybridization studies with whole-chromosome painting and centromere-specific probes for chromosome 21 verified the diagnosis of idic(21)(q22). There were no distinct clinicohematological characteristics of AML with isodicentric 21. The patient was treated with remission-induction therapy followed by consolidation therapy. Two years later, the patient showed the disappearance of isodicentric 21 but retained del(5)(q13q32) and gained other chromosomal abnormalities, +add(17)(p11) and -16. To our knowledge, this is the first report of AML with acquired idic(21)(q22).

Aged↗
PubMed1998

Adaptive acquisition of novobiocin resistance in Pasteurella multocida strains of avian origin.

Naturally occurring strains of Pasteurella multocida are atypically susceptible to hydrophobic antibiotics such as novobiocin, despite their Gram-negative cell envelope ultrastructure. Four strains adaptively resistant to 1000 micrograms/ml of novobiocin were obtained by sequentially subculturing cell surface hydrophobic variants of avian origin in the presence of increasing antibiotic concentrations. Adaptive novobiocin resistance was accompanied in all cases by the concomitant acquisition of resistance to coumermycin, a hydrophobic antibiotic possessing the same mechanism of action, but not to the functionally disparate hydrophobic antibiotic rifamycin. The acquisition of resistance was not accompanied by alterations in the lipid composition of the cell envelope. Subsequent growth of adaptively resistant strains in the absence of novobiocin did not result in the restoration of susceptibility to either novobiocin or coumermycin. Acquisition of adaptive resistance in encapsulated parental strains resulted in an inability to synthesize capsular material and enhanced cell surface hydrophobicity; however, parental encapsulation and decreased cell surface hydrophobicity were restored upon removal of novobiocin. These data suggest that acquisition of adaptive resistance to novobiocin conferred in this manner is the result of a stable genetic event affecting the mechanistic target of both novobiocin and coumermycin rather than a physiological adaptation involving outer membrane impermeability.

Acclimatization↗
PubMed1998

Identification of a commonly deleted region at 17p13.3 in leukemia and lymphoma associated with 17p abnormality.

Fluorescence in situ hybridization (FISH) was performed in 17 myeloid leukemia patients and seven lymphoid leukemia/ lymphoma patients who exhibited chromosomal abnormalities on the short arm of chromosome 17, in order to detect a commonly deleted region on chromosome band 17p13. Twenty-four leukemia/lymphoma patients studied cytogenetically at our institution over a period of 10 years had detectable 17p abnormalities such as translocation (six patients), addition (11 patients) and deletion of 17p13 (seven patients). A 17p abnormality was the only abnormality present in three patients. Most of the patients had additional complex cytogenetic abnormalities. The diagnosis was acute myeloid leukemia (AML) in 10 patients, two each with chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL) and myelodysplastic syndrome (MDS) and the remaining three with malignant lymphoma (ML). Seven cosmid probes (D17S34, cCI17-624, cCI17-453, D17S379, cCI17-636, cCI17-732 and TP53) which mapped on 17p13 were used to analyze the allelic deletion. Eighty percent (19 out of 24) of the informative leukemia patients exhibited allelic loss in 17p13.3 at cC17-624. The smallest region of an overlapping deletion was observed on chromosome band 17p13.3 between cCI17-624 and cCI17-453. Patients with translocation involving 17p also showed deletion at cCI17-624 and cCI17-453. We hypothesize that this region contains a novel tumor suppressor gene(s) that is involved in leukemogenesis.

Adult↗
PubMed1998

Seroprevalence of human T-lymphotropic virus type I (HTLV-I) in Saudi Arabia.

During the past 6 years, blood donors at various hospitals and blood banks in Saudi Arabia have been screened by enzyme immuno-assay for antibodies to human T-lymphotropic virus type I (anti-HTLV-I). Seropositivity for anti-HTLV-I, clearly confirmed by western blot, was only demonstrable in three out of the 34,541 subjects (including at least 21,000 Saudi nationals). The three positives were all expatriates: two Indians and one Syrian. Another six subjects, who gave ambiguous reactions on western blots and may also have been positive, were also all expatriates. Saudi Arabia therefore appears to be a non-endemic area for HTLV-I and hence the current practice of screening all blood donors for anti-HTLV-I does not seem to be cost-effective. An alternative strategy, in which only expatriate blood donors are screened, should perhaps be considered by the Saudi Ministry of Health.

Adult↗
PubMed1998

Association of sequences in the coat protein/readthrough domain of potato mop-top virus with transmission by Spongospora subterranea.

A monofungal culture of Spongospora subterranea was unable to acquire and transmit the T isolate of potato mop-top pomovirus (PMTV-T), which has been maintained by manual transmission in the laboratory for 30 years. A recently obtained field isolate (PMTV-S) was efficiently acquired and transmitted by the same fungus culture. Sequence analysis of the readthrough (RT) protein-coding region of PMTV-S showed the presence of an additional 543 nt in the 3' half of the coding region relative to that of PMTV-T. These additional nucleotides preserved the reading frame of the RT protein and inserted 181 amino acids into the RT protein. This was confirmed by a comparison by immunoblotting of the sizes of the RT protein of PMTV-T and other recent isolates of PMTV.

Amino Acid Sequence↗
PubMed1997

Frequent jumping translocations of chromosomal segments involving the ABL oncogene alone or in combination with CD3-MLL genes in secondary leukemias.

Seven secondary leukemia patients were treated for solid tumors or malignant lymphoma with anticancer drugs or radiation. We studied bone marrow samples from these patients by fluorescence in situ hybridization (FISH). Of the seven patients, three had increased signals for the ABL oncogene (9q34) on interphase nuclei and at metaphase. One of the three patients also had four signals for the CD3 (MLL) region (11q23). Whole painting probes revealed that these chromosomal regions were translocated onto structurally abnormal chromosomes, resulting in partial tri-, tetra- or penta-somy of these regions. We called this type of translocation "segmental jumping translocation (SJT)." SJT of the ABL oncogene was not detected in samples from 15 patients with de novo acute myelocytic leukemia (AML), 12 with myelodysplastic syndrome (MDS), or 20 with chronic myelocytic leukemia (CML) at the chronic phase. Furthermore, monosomy 7 was also found in the patients with the gene amplification. These results indicate that SJT of ABL and/or CD3 (MLL) genes is associated with the leukemogenesis of secondary leukemia. The SJT may be one mechanism of gene amplification.

Aged↗