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Biomedical subjects

M Arif

Publications and source records attributed to M Arif.

At least 19 recordsLinked to original sources
PubMed2006

Measurement of natural radioactivity in bottled drinking water in Pakistan and consequent dose estimates.

Natural radioactivity was determined in 11 different brands of commonly sold bottled drinking water in the federal capital Islamabad and Rawalpindi city of Pakistan using gamma spectrometry technique. Mean concentrations of 226Ra, 232Th and (40)K were found to be 11.3 +/- 2.3, 5.2 +/- 0.4 and 140.9 +/- 30.6 mBq l(-1), respectively. The annual cumulative effective doses due to all three natural radionuclides for different age groups of 1-5 y, 5-10 y, 10-15 y and adults (>or=18 y) were estimated to be 4.0, 3.4, 3.1 and 4.1 microSv y(-1), respectively. Among the three natural radionuclides, annual effective doses for all age groups from 226Ra were significant. Children in the age group of 1-5 y appeared to be at risk with respect to the annual effective doses from 226Ra as compared to the other age groups. Results obtained in this study are compared with the reported values from other countries of the world and it was observed that measured activity concentrations of three natural radionuclides in the bottled drinking water were lower than these values. Annual estimated effective doses for all four age groups from the intake of natural radionuclides in bottled drinking water were also found below the World Health Organisation (WHO) recommended limit of 0.1 mSv y(-1) as well as the average radiation dose of 0.29 mSv y(-1) received per head worldwide due to ingestion of natural radionuclides assessed by UNSCEAR (2000).

Adolescent↗
PubMed2006

Complex genetic networks underlying the defensive system of rice (Oryza sativa L.) to Xanthomonas oryzae pv. oryzae.

Complete resistance (CR) and partial resistance (PR) of rice (Oryza sativa L.) to its bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo), was genetically dissected by using 2 mapping populations and 10 Xoo races. Two CR genes, 50 quantitative resistance loci, and 60 digenic interactions were identified, which showed various degrees of race specificity to the Xoo races. The complex epistasis between these loci led us to the discovery of complex genetic networks underlying the rice defensive system to Xoo. The networks consisted of two major components: one representing interactions between alleles at the R loci of rice and alleles at the corresponding avirulence loci of Xoo for CR and the other comprising interactions between quantitative resistance loci in rice and their corresponding aggressiveness loci in Xoo for PR. The race specificity of PR and its strong genetic overlap with CR indicate that PR is essentially "weaker" CR. The genetic networks discovered are expected to maintain a high level of the allelic diversity at avirulent loci in the pathogen by stabilizing selection, which may maintain a high allelic diversity at R loci in the host by the frequency-dependent selection.

Alleles↗
PubMed2006

Chain morphologies in semicrystalline polyfluorene: evidence from Raman scattering.

The beta phase in di-octyl substituted polyfluorene (PF8) exhibits a surprising level of conformational order at nanometer length scales compared to other phases. We present Raman scattering studies of PF8 as a function of thermal cycling, which establishes a connection between the conformational isomers and the side and main chain morphology. Density-functional calculations of the vibrational spectra of single chain oligomers in conjunction with the experimental results demonstrate the incompatibility of the beta phase with the overall alpha crystalline phase in PF8.

Journal Article↗
PubMed2006

In vitro antibacterial, antifungal & cytotoxic activity of some isonicotinoylhydrazide Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes.

Isonicotinoylhydrazide Schiff's bases formed by the reaction of substituted and unsubstituted furyl-2-carboxaldehyde and thiophene-2-carboxaldehyde with isoniazid and, their Co (II), Cu (II), Ni (II) and Zn (II) complexes have been synthesized, characterized and screened for their in vitro antibacterial activity against Mycobacterium tuberculosis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureus and Streptococcus pyogenes bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. The results of these studies show the metal complexes to be more antibacterial and antifungal against one or more bacterial/fungal strains as compared to the uncomplexed compounds. The brine shrimp bioassay indicated Schiff's bases, L3 and L6 and, their Cu (II) and Ni (II) metal complexes to be cytotoxic against Artemia salina, while all other compounds were inactive (LD50 > 1000).

Animals↗
PubMed2005

Activity Concentration of 137Cs in soil samples from Punjab province (Pakistan) and estimation of gamma-ray dose rate for external exposure.

Punjab is one of the most populated provinces of Pakistan having 34 districts. There is always a need to have baseline background level information about 137Cs and the corresponding gamma-ray doses to the population. In this respect, soil samples were collected to a depth of 30-50 cm from all 34 district headquarters of the Punjab province of Pakistan and 137Cs activity concentrations were measured. 137Cs activity concentration was found to be in the range from 1.1 +/- 1.0 to 5.3 +/- 2.5 Bq kg(-1). The average value of estimated external gamma-ray dose rate from all 34 districts of Punjab province was computed to be 0.18 +/- 0.07 nSv h(-1) from 137Cs in soil samples. The measured 137Cs activity concentration range was compared with the reported ranges in the literature from some of the other locations in the world. Results obtained in this study show that 137Cs concentration is of a lower level in the investigated area. The average value of estimated external effective dose rate is found far below the dose rate limit of 1.0 mSv y(-1) for members of the general public recommended by the International Commission on Radiological Protection (ICRP) as well as the external gamma radiation dose of 0.48 mSv y(-1) received per head from the natural sources of radiation assessed by UNSCEAR (2000). It is concluded that 137Cs soil contamination does not pose radiation hazards to the population in the investigated areas.

Body Burden↗
PubMed2005

Application of threshold-based acceleration change index (TACI) in heart rate variability analysis.

Heart rate variability (HRV) analysis is a non-invasive and reliable means to assess an autonomic nervous system (ANS) function. Heart rate is a non-stationary signal that may contain indicators of current diseases and sometimes warnings about impending diseases. In this paper, we have proposed the threshold-based acceleration change index (TACI) for HRV analysis, which is calculated from the sign of differences of RR time series characterizing the dynamics of threshold crossings. It was found that TACI is robust in classifying various groups under different physiological and pathological conditions. We have studied the behavior of TACI for simulated time series (uncorrelated random data, sinusoidal time series and logistics map time series) and its robustness in the presence of artifacts for RR time series. The performance of TACI is evaluated for classifying normal sinus rhythm (NSR), congestive heart failure (CHF) and atrial fibrillation (AF). An unpaired Student's t-test was used to check significant differences between these groups and the degree of separation between these groups was quantified by using the area of a receiver operator curve.

Atrial Fibrillation↗
PubMed2005

Measurements of activity concentrations of naturally occurring radionuclides in soil samples from Punjab province of Pakistan and assessment of radiological hazards.

The natural level of radioactivity in soil is one of the major causes of external gamma rays exposure. It was considered imperative to measure gamma-ray activity concentrations due to naturally occurring, potentially hazardous radionuclides from 232Th, 226Ra and 40K in soil samples from Punjab, the most populated province of Pakistan. The activity concentrations were measured in soil samples collected from all 34 district headquarters of Punjab province using a P-type coaxial high purity germanium (HPGe)-based gamma-ray spectrometer having a relative efficiency of 60%. The mean activity concentrations for 232Th, 226Ra and 40K were found to be 41 +/- 8, 35 +/- 7 and 615 +/- 143 Bq kg(-1), respectively in soil samples from all 34 district headquarters of Punjab. The mean values of radium equivalent index (Ra(eq)) and total annual external gamma radiation dose were found to be 141 +/- 27 Bq kg(-1)and 0.38 mSv, respectively. Since these estimated radiological impact assessment factors are lower than the recommended values there seems to be no potential radiological health hazard associated with the soils from the district headquarters in the Punjab province of Pakistan. Geological studies show that most of the soils in Punjab have developed on the extensive fluviatile deposits of five rivers and a stable ratio of natural activity concentrations is observed in soil samples of the areas under study.

Air Pollution, Radioactive↗
PubMed2005

Kerion: an unusual presentation in the otolaryngology department.

A 19-year-old farmer was referred by his general practitioner as an emergency to our otolaryngology department complaining of marked breathlessness of a few hours duration. He gave a three-day history of painful swelling and hair loss in the beard area of the right side of the neck. His upper airway was compromised unless extension of the neck was maintained. Larynx and pharynx were normal. The acute symptoms settled with intravenous antibiotics and hydrocortisone. Culture of skin scrapings revealed a growth of Tricophyton verrucosum. The neck swelling subsided after a course of oral griseofulvin followed by terbinafine. Difficulty in breathing due to fungal infection of the neck has not been previously reported in the English literature.

Adult↗
PubMed2005

Antibacterial activity of 1-methyl-7-methoxy-beta-carboline and its phenacyl and coumarine analogues.

Antibacterial activity of 1-methyl-7-methoxy-beta-carboline (harmaline) and its phenacyl and coumarine analogues 1-(3-nitro-phenyl)-(2-(7-methoxy-1-methyl-1,3,4,9-tetrahydro-beta-carbolin-2-yl)-ethanone (II), 1-(3,4-dihydroxy-phenyl)-2-(7-methoxy-1-methyl-1,3,4,9-tetrahydro-beta-carbolin-2-yl)-ethanone (III) 7-(methoxy-beta-carboline),15-24,de-hydro(19,20-dimethoxy)coumarine (IV), 7-(methoxy-beta-carboline)15-24,dehydro(20-methoxy)coumarine (V) were studied by disc diffusion method. All compounds were tested against three gram positive and four gram-negative bacteria. Parent compound showed good activity. All compounds revealed better results against gram positive as compared to gram-negative bacteria. 1-(3,4-Dihydroxy-phenyl)-2-(7-methoxy-1-methyl-1,3,4,9-tetrahydro-beta-carbolin-2-yl)-ethanone (III) was found most potent compound showing broad spectrum activity when compared with all synthesized analogues. Coumarine analogues showed more or less same activity indicating that number and position of methoxy groups are not important regarding antimicrobial activity.

Anti-Bacterial Agents↗
PubMed2005

Early results of Rotating Platform total knee replacement.

We report on our early experiences with the Press Fit Condylar Rotating Platform (PFC-RP) total knee replacement prosthesis at University Malaya Medical Centre. This new prosthesis was introduced to Malaysia in 2001. It combines the rotating platform technology of Low Contact Stress (LCS) and the modularity of Press Fit Condylar (PFC) system. We performed 18 knee replacements using cruciate retaining prosthesis without patellar resurfacing in 10 patients and followed them up over a period of 16-month. A new operative strategy was developed to match the flexion and extension gaps. The pre- and post-operative assessments were made according to the American Knee Society Scores (AKSS). Post-operative pain relief, range of motion, knee score and functional score showed promising early results. The average knee rating improved from 28 to 91 (range 75-94). Average functional assessment improved from 26 to 82 (range 75-90). The radiographic assessments show correction of an average pre-operative varus of 140 to post-operative valgus of 50 (range 4-70). Early infection occurred in two knees. Both responded to aggressive debridement and antibiotics. Stiffness was encountered in one patient. There were no spinouts of the insert. We are satisfied that the implants are performing well at the one-year mark and will continue monitor this cohort.

Aged↗
PubMed2004

Measurement of presynaptic zinc changes in hippocampal mossy fibers.

The hippocampal mossy fiber terminals of CA3 area contain high levels of vesicular zinc that is released in a calcium-dependent way, following high-frequency stimulation. However the properties of zinc release during normal synaptic transmission, paired-pulse facilitation and mossy fiber long-term potentiation are still unknown. Using the fluorescent zinc probe N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide, we measured fast mossy fiber zinc changes indicating that zinc is released following single and low levels of electrical stimulation. The observed presynaptic zinc signals are maintained during the expression of mossy fiber long-term potentiation, assumed to be mediated by an increase in transmitter release, and are enhanced during paired-pulse facilitation. This zinc enhancement is, like paired-pulse facilitation, reduced during established long-term potentiation. The correlation between the paired-pulse evoked zinc and field potential responses supports the idea that zinc is co-released with glutamate.

2-Amino-5-phosphonovalerate↗
PubMed2004

Thermal and cold neutron phase-contrast radiography.

In this paper, we will discuss a phase-contrast imaging method that avoids the complications of interferometry to provide phase contrast in weakly absorbing samples. A transversely coherent neutron beam is used with the traditional radiography scheme. Images taken with this scheme show dramatic intensity variations due to sharp changes in the neutron wave refractive index. With some numerical processing these images may be used to reconstruct a quantitative phase radiograph of specimens imaged with this technique.

Journal Article↗
PubMed2004

Revision of total hip arthroplasty using an anterior cortical window, extensive strut allografts, and an impaction graft: follow-up study.

PURPOSE: To report the outcome of revised total hip arthroplasty procedures involving an anterior cortical window, extensive strut allografts, and an Exeter impaction graft. METHOD: Eight patients (9 hips) with a mean age of 58 years underwent revision of total hip arthroplasty using the Exeter hip impaction graft system and strut allografts between 1995 and 1998. An extensile anterior approach was used, and an anterior cortical window was created in the femur, to remove the old implant. External strut allografts were attached by wires to provide cortical support. The mean follow-up duration was 74 months. Indications for surgery were aseptic loosening of previous implants in 8 hips and infection of one hip that had previously undergone total arthroplasty. RESULTS: 19 Dall Miles cables, 4 ordinary cerclage wires, and 8 cerclage wires tightened with the clincher knot technique were used to secure the allograft to the host bone. The strut grafts were found to be incorporated in all cases. No wires became loose. One patient developed 20 degrees of angulation at the allograft-host bone junction. Using the method of Fowler and Gie, we found that one femoral implant had subsided 2 mm within the cement mantle. Two other implants had 1 mm of subsidence at the cement bone interface, and one patient had a major subsidence of 15 mm that required revision. CONCLUSION: Using an anterior cortical window in the femur to remove the old implant does not predispose to failure of the allograft to incorporate into the host bone.

Adult↗
PubMed2003

Quantitative phase radiography with polychromatic neutrons.

We develop and experimentally demonstrate a formalism that allows accurate phase imaging using neutron sources producing highly polychromatic beams. The results of measurements from a rectangular block of silicon compare favorably with theoretical simulations based upon the known composition and geometry of the block. The increased flux and reduced exposure times will permit a simple extension of the technique to tomographic phase imaging.

Journal Article↗
PubMed2003

Precision neutron interferometric measurement of the nd coherent neutron scattering length and consequences for models of three-nucleon forces.

We have performed the first high precision measurement of the coherent neutron scattering length of deuterium in a pure sample using neutron interferometry. We find b(nd)=(6.665+/-0.004) fm in agreement with the world average of previous measurements using different techniques, b(nd)=(6.6730+/-0.0045) fm. We compare the new world average for the nd coherent scattering length b(nd)=(6.669+/-0.003) fm to calculations of the doublet and quartet scattering lengths from several modern nucleon-nucleon potential models with three-nucleon force (3NF) additions and show that almost all theories are in serious disagreement with experiment. This comparison is a more stringent test of the models than past comparisons with the less precisely determined doublet scattering length of (2)a(nd)=(0.65+/-0.04) fm.

Journal Article↗
PubMed2003

Small stem Exeter total hip replacement: clinical and radiological follow-up over a minimum of 2.5 years.

PURPOSE: To evaluate the clinical and radiological outcome in patients undergoing small stem Exeter total hip replacement. METHODS: A total of 46 small stem Exeter total hip replacements were performed on 44 consecutive patients (18 men and 26 women) attending the University of Malaya Medical Centre. The mean age at the time of operation was 58 years (range, 24-81 years). Of the 46 procedures performed, 35 were primary total hip replacements and 11 were revision operations, with aseptic loosening of the original implant being the main indication for revision. The main indications for surgery in primary cases were avascular necrosis and rheumatoid arthritis. Clinical and radiographic outcomes were assessed at 6 weeks', 12 weeks', 6 months' follow-up, and annually thereafter. Postoperative cementing technique was also assessed. RESULTS: The mean follow-up period was 4 years. The mean Oxford Hip Score improved from 46 points preoperatively to 17 points at the final follow-up examination. There were no revision operations, no implant breakages, and no excessive migration of the implants. The potential complications of implant failure due to smaller implant size and increased patient activity were not observed. CONCLUSION: Due to the smaller size of Asian femora, the small stem Exeter implant is a very useful development. This study suggests that it will perform as well as its larger counterparts.

Adult↗