Biomedical subjects

S Ahmad

Publications and source records attributed to S Ahmad.

At least 19 recordsLinked to original sources

PubMed2007

Effect of immersion disinfection with Perform-ID on alginate, an alginate alternative, an addition-cured silicone and resultant type III gypsum casts.

OBJECTIVE: This study investigated the effect of a commonly used immersion disinfectant upon three different impression materials and any subsequent effects on the abrasion resistance, hardness and surface detail reproduction of gypsum casts. DESIGN: A laboratory study. MATERIALS AND METHODS: Under standardised conditions a total of 120 impressions were made of a ruled test block using irreversible hydrocolloid (Alginoplast), an 'alginate alternative' addition-cure silicone (Position Penta) and a conventional addition-cure silicone (President). The impressions were examined for surface detail reproduction prior to and after disinfection with Perform-ID. The type III casts were evaluated for surface detail reproduction, surface hardness and abrasion resistance. RESULTS: (1) None of the disinfected alginate specimens could reproduce the 50 microm line. (2) Casts produced from the disinfected alginate were significantly less hard than from disinfected Position Penta and President (P <0.001). (3) Disinfection significantly affected the abrasion resistance of casts made from Position Penta (P = 0.029). (4) Disinfection did not significantly affect President or its subsequent casts (P >0.05). CONCLUSION: If disinfecting with Perform-ID, the impression should be made with a conventional addition-cured silicone if good surface detail reproduction of the impression material and a hard and abrasion resistant type III gypsum cast are required.

Alginates↗

PubMed2006

MRI-based measurements of respiratory motion variability and assessment of imaging strategies for radiotherapy planning.

Respiratory organ motion has a significant impact on the planning and delivery of radiotherapy (RT) treatment for lung cancer. Currently widespread techniques, such as 4D-computed tomography (4DCT), cannot be used to measure variability of this motion from one cycle to the next. In this paper, we describe the use of fast magnetic resonance imaging (MRI) techniques to investigate the intra- and inter-cycle reproducibility of respiratory motion and also to estimate the level of errors that may be introduced into treatment delivery by using various breath-hold imaging strategies during lung RT planning. A reference model of respiratory motion is formed to enable comparison of different breathing cycles at any arbitrary position in the respiratory cycle. This is constructed by using free-breathing images from the inhale phase of a single breathing cycle, then co-registering the images, and thereby tracking landmarks. This reference model is then compared to alternative models constructed from images acquired during the exhale phase of the same cycle and the inhale phase of a subsequent cycle, to assess intra- and inter-cycle variability ('hysteresis' and 'reproducibility') of organ motion. The reference model is also compared to a series of models formed from breath-hold data at exhale and inhale. Evaluation of these models is carried out on data from ten healthy volunteers and five lung cancer patients. Free-breathing models show good levels of intra- and inter-cycle reproducibility across the tidal breathing range. Mean intra-cycle errors in the position of organ surface landmarks of 1.5(1.4)-3.5(3.3) mm for volunteers and 2.8(1.8)-5.2(5.2) mm for patients. Equivalent measures of inter-cycle variability across this range are 1.7(1.0)-3.9(3.3) mm for volunteers and 2.8(1.8)-3.3(2.2) mm for patients. As expected, models based on breath-hold sequences do not represent normal tidal motion as well as those based on free-breathing data, with mean errors of 4.4(2.2)-7.7(3.9) mm for volunteers and 10.1(6.1)-12.5(6.3) mm for patients. Errors are generally larger still when using a single breath-hold image at either exhale or inhale to represent the lung. This indicates that account should be taken of intra- and inter-cycle respiratory motion variability and that breath-hold-based methods of obtaining data for RT planning may potentially introduce large errors. This approach to analysis of motion and variability has potential to inform decisions about treatment margins and optimize RT planning.

Humans↗

PubMed2006

Catheter-associated fungemia due to Exophiala oligosperma in a leukemic child and review of fungemia cases caused by Exophiala species.

A case of catheter-associated fungemia due to Exophiala oligosperma in a 3-year-old leukemic child is presented. The etiologic agent was isolated from blood specimens and the catheter tip. The isolate was identified by its morphological characteristics and DNA sequencing of the internal transcribed spacer region of rDNA. Despite initial amphotericin B and itraconazole therapy, the child's fever subsided only after removal of the catheter. A review of the medical literature revealed 29 cases of infection due to Exophiala species. Twenty-three of these 29 patients had a CVC in place when they developed fever or other manifestations of fungemia. Withdrawal of the CVC together with amphotericin B and/or itraconazole therapy generally resulted in a good prognosis.

Catheterization, Central Venous↗

PubMed2006

Impact of new dialysis solutions on peritonitis rates.

Peritonitis remains a major cause of morbidity among patients on peritoneal dialysis (PD), yet there is little information about the effect of new biocompatible dialysis solutions on peritonitis rates and treatment. In our unit, information on each peritonitis episode is prospectively collected. Since 2003, bicarbonate/lactate dialysate has been gradually introduced for new patients and for patients experiencing abdominal pain with conventional lactate solutions. From 2002 to 2005, data from 121 episodes of peritonitis (71 automated PD and 50 continuous ambulatory PD) were analyzed; 107 episodes occurred in patients using standard lactate dialysate and 14 episodes in patients using bicarbonate/lactate solution. Patients using bicarbonate/lactate had a significantly lower peritonitis rate of 1 per 52.5 patient-months compared to those using standard lactate dialysate (1 per 26.9 patient-months) (P=0.0179). Response to treatment, however, was not affected by the type of dialysate; cure rates (71.4 and 69.1%, respectively) and recurrence rates (21.4 and 15.8%, respectively) were not significantly different. Catheter removal was required in three (21.4%) patients using bicarbonate/lactate and 23 (22.4%) patients using lactate solution. Use of biocompatible dialysate appears to reduce the peritonitis rate by 50%, although this has to be confirmed in a randomized study. The type of dialysate, on the other hand, does not affect response to treatment.

Bicarbonates↗

PubMed2006

An experience of emergency ultrasonography in children in a sub-Saharan setting.

Emergency ultrasonography is an appealing imaging modality in paediatric emergencies, given its non-invasive nature and potential as an adjunct to physical examination in a setting where rapid decisions need to be made. This review of a case series describes the applications, versatility, and limitations of emergency physician led ultrasonography in a paediatric resuscitation room in a sub-Saharan African setting.

Africa South of the Sahara↗

PubMed2006

Estimating injury severity using the Barell matrix.

OBJECTIVE: To determine whether the Barell matrix (Inj Prev 2002;8:91-6) could effectively categorize injuries by severity. METHODS: Injury diagnoses of cases in the 2002 US Nationwide Inpatient Sample were classified according to the Barell matrix. For each cell of the matrix, the authors used ICDMAP-90 to determine the predominant Abbreviated Injury Score (AIS) and body region, and calculated the weighted proportion surviving (bPScell) among patients with any diagnosis in that cell. These findings were used to estimate maximum AIS (bAISmax), ISS (bISS), and the minimum or product of bPScell (bPSmin, bPSprod) for injured patients in the 1996-2000 US National Hospital Discharge Surveys. Case survival was determined for different scores, and outcome models using age, sex, comorbidity, mechanism, and bISS or bPSmin were compared to models using ISS calculated from ICDMAP-90 (mISS) or using ICISS. RESULTS: Case survival decreased with increasing bAISmax or bISS; survival was closely approximated by bPSmin, and also increased monotonically with bPSprod. Outcome models using bISS or bPSmin were similar to those using mISS or ICISS. An Abbreviated Barell Categorization, with only four groups, was also effective. CONCLUSION: Barell matrix categorization of administrative data allows severity scoring similar to that obtainable with ICDMAP-90 or ICISS.

Hospital Mortality↗

PubMed2006

Audit of a diabetes clinic at Tawam hospital, United Arab Emirates, 2004-2005.

The aim of this audit was to determine the current management of patients with diabetes compared to international standards and to benchmark the results against current international standards. A retrospective audit of medical records of diabetic patients attending Tawam Hospital, a tertiary healthcare facility in the Al Ain region in the Emirate of Abu Dhabi, United Arab Emirates was performed. A random sample of 30 patients (5% of the target group) was selected from the total number of 600 patients who visited the diabetes clinics in August 2005. An audit form was developed based on the priority aims and measures contained in the Institute for Clinical Systems Improvement (ICSI) Guidelines for the management of type 2 diabetes mellitus. Data analysis was carried out based on measurement specifications in the ICSI Guidelines. All patients had their blood pressure checked at their most recent appointment. All except one patient had an HbA1c test and a lipid profile performed during the study period. Although 75% of patients were referred for a dilated eye examination, only 47% complied. Approximately two-thirds of all patients had evidence of self-monitoring of blood glucose. Less than half of the patients were referred to the nutritionist and only a relatively small proportion of patients had advice on diet and exercise documented in their medical record. There was also lack of documentation, particularly for smoking status, foot examination, and body mass index (BMI). All patients received aspirin (ASA) treatment. The majority had a systolic blood pressure of 130 mmHg or less; just under half of patients had HbA1c of less than 7%. In comparison to the Center for Diseases Control (CDC) targets, we exceeded targets in three areas in relation to HbA1c testing, ASA treatment, and self-report monitoring blood glucose. We did not meet the stated target of 75% for patients having a dilated eye exam due to lack of patient compliance (more than three-quarters of all patients were referred but did not attend for appointment). Documentation of a comprehensive foot examination was present for only one-quarter of all patients compared to the recommended target of three-quarters of patients. Documentation of advice on diet and exercise was present for 40%, which did not meet the CDC target of 60%. Overall, the audit highlighted that Tawam Hospital is providing a good level of care to diabetic patients and compares favorably with international targets; however, key recommended actions have been identified for implementation to improve patient care and maintain a continuous improvement process through effective monitoring with prioritization to those related to preventative care.

Diabetes Mellitus↗

PubMed2006

Fungemia caused by Verticillium species in an immunocompromised child.

The incidence of fungal infections is increasing due to immunocompromised states. We report a case of fungaemia due to a rare fungus - Verticillium, in a 6 year old child diagnosed as a case of acute lymphoblastic leukaemia- L1 with high grade fever. The patient was treated with amphotericin B with a good clinical response.

Amphotericin B↗

PubMed2005

High-precision dosimetry for radiotherapy using the optically stimulated luminescence technique and thin Al2O3:C dosimeters.

The potential of using the optically stimulated luminescence (OSL) technique with aluminium oxide (Al(2)O(3):C) dosimeters for a precise and accurate estimation of absorbed doses delivered by high-energy photon beams was investigated. This study demonstrates the high reproducibility of the OSL measurements and presents a preliminary determination of the depth-dose curve in water for a 6 MV photon beam from a linear accelerator. The uncertainty of a single OSL measurement, estimated from the variance of a large sample of dosimeters irradiated with the same dose, was 0.7%. In the depth-dose curve obtained using the OSL technique, the difference between the measured and expected doses was < or =0.7% for depths between 1.5 and 10 cm, and 1.1% for a depth of 15 cm. The readout procedure includes a normalization of the response of the dosimeter with respect to a reference dose in order to eliminate variations in the dosimeter mass, dosimeter sensitivity, and the reader's sensitivity. This may be relevant for quality assurance programmes, since it simplifies the requirements in terms of personnel training to achieve the precision and accuracy necessary for radiotherapy applications. We concluded that the OSL technique has the potential to be reliably incorporated in quality assurance programmes and dose verification.

Aluminum Oxide↗

PubMed2005

Introduction of HIV post-exposure prophylaxis for sexually abused children in Malawi.

AIMS: To improve the care of children who are victims of child sexual abuse (CSA) by routinely assessing eligibility for HIV post-exposure prophylaxis (PEP) and to investigate the feasibility, safety, and efficacy of such treatment started in a paediatric emergency department in Malawi. METHODS: Children presenting to the Queen Elizabeth Central Hospital, Blantyre between 1 January 2004 and 31 December 2004 with a history of alleged CSA were assessed for eligibility for HIV PEP and followed prospectively for six months. RESULTS: A total of 64 children presented with a history of alleged CSA in the 12 month period; 17 were offered PEP. The remainder were not offered PEP because of absence of physical signs of abuse (n = 20), delay in presentation beyond 72 hours from assault (n = 11), repeated sexual abuse in the preceding six months (n = 15), and HIV infection found on initial testing (n = 1). No family refused an HIV test. No side effects due to antiretroviral therapy were reported. Of the 17 children commenced on PEP, 11 returned for review after one month, seven returned at three months, and two of 15 returned at six months post-assault. None have seroconverted. CONCLUSIONS: In a resource-poor setting with a high HIV prevalence, HIV PEP following CSA is acceptable, safe, and feasible. HIV PEP should be incorporated in to national guidelines in countries with a high community prevalence of HIV infection.

Adolescent↗

PubMed2005

Stability-indicating HPTLC determination of curcumin in bulk drug and pharmaceutical formulations.

A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of curcumin both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60 F-254 as the stationary phase. The solvent system consisted of chloroform:methanol (9.25:0.75 v/v). This system was found to give compact spots for curcumin (R(f) value of 0.48 +/- 0.02). Densitometric analysis of curcumin was carried out in the absorbance mode at 430 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r = 0.996 and 0.994 with respect to peak height and peak area, respectively, in the concentration range 50-300 ng per spot. The mean value +/- S.D. of slope and intercept were 1.08 +/- 0.01, 51.93 +/- 0.54 and 8.39 +/- 0.21, 311.55 +/ -3.23 with respect to peak height and area, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 8 and 25 ng per spot, respectively. Curcumin was subjected to acid and alkali hydrolysis, oxidation and photodegradation. The drug undergoes degradation under acidic, basic, light and oxidation conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and photo oxidation. Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of said drug. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one.

Calibration↗

PubMed2005

Gastrojejunal strictures following laparoscopic Roux-en-Y gastric bypass for morbid obesity.

BACKGROUND: Gastrojejunal strictures following laparoscopic Roux-en-Y gastric bypass (LRYGBP) present with dysphagia, nausea, and vomiting. Diagnosis is made by endoscopy and/or radiographic studies. Therapeutic options include endoscopic dilation and surgical revision. METHODS: Of 369 LRYGBP performed, 19 patients developed anastomotic stricture (5.1%). One additional patient was referred from another facility. Pneumatic balloons were used for initial dilation in all patients. Savary-Gilliard bougies were used for some of the subsequent dilations. RESULTS: Flexible endoscopy was diagnostic in all 20 patients allowing dilation in 18 (90%). Two patients did not undergo endoscopic dilation because of anastomotic obstruction and ulcer. The median time to stricture development was 32 days (range: 17-85). Most patients (78%) required more than two dilations. The complication rate was 1.6% (one case of microperforation). At a mean follow-up of 21 months, all patients were symptom-free. CONCLUSIONS: Gastrojejunostomy stricture following LRYGBP is associated with substantial morbidity and patient dissatisfaction. Based on our experience, we propose a clinical grading system and present our strategy for managing gastrojejunal strictures.

Adult↗

PubMed2005

Impact of margin on tumour and normal tissue dosimetry in prostate cancer patients treated with IMRT using an endorectal balloon for prostate immobilization.

In IMRT treatment, margin for planning target volume is determined by organ motion and set-up error. The margin width that achieves the desired dose escalation, while minimizing normal tissue exposure is dependent upon patient immobilization and/or organ localization techniques. In this study, we compare the impact of margin width on the dosimetry of tumour and normal tissues using an endorectal balloon filled with 100 cc of air. Plans were generated for ten patients using margin widths of 0, 3, 5, 8 and 10 mm. The prescription dose to prostate and seminal vesicles was 70 Gy in 35 fractions with 15% of bladder allowed to receive above 65 Gy, 15% of rectum above 68 Gy and 10% of femurs above 45 Gy. Margins above 5 mm produced significantly lower mean doses for both prostate and seminal vesicles without affecting TCP. For normal tissues, mean doses, percent volumes above prescription constraints and NTCP increased as a function of margin width, especially when this was 5 mm or above. We conclude that planning with tighter margins of < or =5 mm improves IMRT dosimetry for prostate and normal tissues and is only possible when target localization and/or immobilization devices are routinely used.

Catheterization↗

PubMed2005

A comparative study based on gender and age dependence of selected metals in scalp hair.

Levels of 10 metals (Ca, Mg, Fe, Zn, Cu, Mn, Cd, Co, Cr and Ni) in the scalp hair of male and female donors, with age groups between 3 and 100 years, were determined by ICP-AES. In total, 58 male and 30 female hair samples were analyzed in triplicate. The donors belonged to the rural area of district Chakwal, a well-known typical non-urban site in Pakistan. Calcium showed the highest concentration of 462 microg/g in the hair of males and 870 microg/g in those of females followed by Zn, at 208 and 251 microg/g for the two sexes. For male donors, Cd showed the lowest concentration (1.15 microg/g) while for female donors Co remained at minimum level (0.92 microg/g). The order of decreasing metal concentration in the hair of male donors was: Ca > Zn > Mg > Fe > Cu > Mn > Ni > Cr > Co > Cd while that for female donors it was: Ca > Zn > Mg > Fe > Cu > Mn > Cr > Ni > Cd > Co. The female group exhibited enhanced levels of all selected metals except Fe and Co in their hair as compared with the male counterparts. A strong bivariate positive correlation was found between Fe and Zn (r = 0.841) for the hair samples from male category while for the female category, strong positive correlations were observed between Ca-Mg (r = 0.617), Ca-Zn (r = 0.569), Ca-Mn (r = 0.565), Mg-Mn (r = 0.655), Cr-Cu (r = 0.655) and Cr-Ni (r = 0.685). The distribution of metals in the hair of donors with respect to different age groups was also investigated for both genders. The study showed that in case of males, the concentration of all selected metals decreased with increasing age except for Cu, Co and Cr. However, for females the hair metal levels increased with age, except for Co for which the concentration decreased with age. No appreciable change in the metal concentration was observed as a function of age for the combined sexes.

Adolescent↗

PubMed2005

Management of vesico-vaginal fistulas in women.

OBJECTIVE: Urinary fistulas resulting from obstetric trauma remains a major problem in developing countries. Surgical success rates, however, range from 61% to 95%. This study reviews the main causes of fistulas, and the surgical techniques and success rates of surgical closure. METHOD: A total of 1086 cases of urinary fistulas resulting from obstetric trauma over 25 years were reviewed. All women received surgical intervention. Various types of fistulas as well as specific surgical techniques are described, and patient age, parity, and probable cause of fistula were compared with findings from studies in Africa. RESULTS: The highest number of cases (47.6%) occurred in women aged between 26 and 35 years; moreover, 54.43% of the women were para 6 and higher. Obstructed labor contributed to 72.78%, cesarean hysterectomy to 7.60%, cesarean section to 7.30%, and other obstetrical traumatic procedures to 12.28% of the cases. Surgical success was achieved in 84.5% of the cases. The major residual problem of stress incontinence was noted in 5% of the cases. CONCLUSION: Besides prevention, the basic principles of fistula repair are the most important factors in achieving surgical success. Better preoperative preparation and rigorous measures for preventing postoperative infection can help increase the success rate of fistula repair.

Adolescent↗

PubMed2005

Some more new etchants for CR-39 detector.

Recently, several new etchants have been reported for CR-39 detector (Molten Ba(OH)2. 8H2O as an etchant for CR-39 detector, Radiat. Meas. 37 (2003) 205; Discovery of new etchants for CR-39 detector, Radiat. Meas. (2004)). We have made further progress in this direction and have unveiled two more new etchants which are reported in this article. CR-39 detectors were irradiated with fission fragments and alpha particles from a thin 252Cf disc source. The irradiated detectors were then etched in our newly introduced etching solutions as well as in conventionally used 6 M NaOH aqueous solution at 70 degrees C. The newly prepared etching solutions included NaOH dissolved in methanol and NaOH dissolved in methanol + water. Optimum values of NaOH concentration in methanol as well as in methanol + water were determined. Optimum etching temperatures were also determined for both the above-mentioned etchants. From fission and alpha track diameters, bulk etching rate (VB), track etching rate (VT) and etching efficiency (eta) were determined and compared with that obtained for 6 M NaOH at 70 degrees C. Both the newly introduced etchants were found more efficient than the conventionally used 6 M aqueous NaOH (64%) at 70 degrees C and have relatively much smaller etching time.

Alpha Particles↗

PubMed2005

Where older people die: a retrospective population-based study.

BACKGROUND: Palliative medicine services have invested in the community to support people dying at home. To develop end-of-life care for older people, we need to know where they die. AIM: To examine trends in age and location of death over the last 20 years. DESIGN: Retrospective death certificate review. METHOD: All Wales death certificates from 1981 to 2001 were examined. Place of death and age were noted. RESULTS: Total deaths decreased from 35,015 in 1981 to 32,966 in 2001, and mortality decreased from 12.45 per 1000 population in 1981 to 11.33 in 2001. Deaths in the community decreased from 37.6% (n = 13,155) to 22.1% (n = 7293) (p < 0.001); deaths increased in hospital from 56.7% (n = 19,871) to 61.7% (n = 20,334) (p < 0.001) and in care homes from 5.7% (n = 1989) to 16.2% (n = 5339) (p < 0.001). Between 1981 and 2001, deaths in those aged 65-74 years dropped from 9752 to 6361, but increased in the over-85s from 5661 to 9779. Deaths amongst 75-84-year-olds remained stable at around 11,000. The biggest rise in hospital and care-home deaths was in those over 85: hospital deaths increased from 2928 in 1981, to 5438 in 2001; care-home deaths increased from 941 to 3141. DISCUSSION: The last 20 years have seen a significant shift in location of death from the community to hospitals and care homes. Those aged over 85 years account for the biggest rise in hospital and care-home deaths. End-of-life needs for older people need to be addressed in hospital and care homes, not just in the community.

Age Distribution↗

PubMed2005

The six mammalian cell entry proteins (Mce3A-F) encoded by the mce3 operon are expressed during in vitro growth of Mycobacterium tuberculosis.

The pathogenesis of Mycobacterium tuberculosis is largely due to its ability to enter and survive within human macrophages. The mammalian cell entry (mce)3 operon is one of four homologous mce operons that encodes six putative invasin-like exported proteins (Mce3A-F), possibly involved in entry and survival of M. tuberculosis inside macrophages. We have recently shown that Mce3A, Mce3D and Mce3E are expressed and elicit antibody responses in a majority of human subjects during natural infection with M. tuberculosis. In this study, we demonstrate the expression of Mce3A-F proteins and their mRNA during in vitro growth of M. tuberculosis. To demonstrate the expression of mce3A-F proteins, the antibodies were raised in rabbits against three pure proteins (Mce3A, Mce3D and Mce3E), and their specificity was checked by immunoblotting with recombinant Mce1A-F proteins encoded by mce1 operon. The antibodies were also generated against all the six Mce3 proteins, which were expressed and purified as fusion proteins with glutathione S-transferase (GST) as the fusion partner (GST-Mce3A-F). The antibodies reacted, in each case, with a protein of expected molecular mass (Mr) for the corresponding Mce3 protein in the cell wall fraction but not in the soluble fraction of in vitro-grown M. tuberculosis cells. The presence of mRNA for mce3A-F genes was also shown by using mce3A-F gene-specific primers, and total RNA isolated from in vitro-grown M. tuberculosis cells by reverse transcription-polymerase chain reaction (RT-PCR). Pretreatment of the RNA preparation with RNase A abolished amplification in RT-PCR confirming that mce3A-F mRNA rather than genomic DNA was being amplified. The data show that Mce3A-F encoded by the mce3 operon are expressed during in vitro growth of M. tuberculosis.

Animals↗