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Biomedical subjects

W Ahmed

Publications and source records attributed to W Ahmed.

At least 19 recordsLinked to original sources

Comparison of the efficacy of an existing versus a locally developed metabolic fingerprint database to identify non-point sources of faecal contamination in a coastal lake.

A comparison of the efficacy of an existing large metabolic fingerprint database of enterococci and Escherichia coli with a locally developed database was undertaken to identify the sources of faecal contamination in a coastal lake, in southeast Qld., Australia. The local database comprised of 776 enterococci and 780 E. coli isolates from six host groups. In all, 189 enterococci and 245 E. coli biochemical phenotypes (BPTs) were found, of which 118 and 137 BPTs were unique (UQ) to host groups. The existing database comprised of 295 enterococci UQ-BPTs and 273 E. coli UQ-BPTs from 10 host groups. The representativeness and the stability of the existing database were assessed by comparing with isolates that were external to the database. In all, 197 enterococci BPTs and 179 E. coli BPTs were found in water samples. The existing database was able to identify 62.4% of enterococci BPTs and 64.8% of E. coli BPTs as human and animal sources. The results indicated that a representative database developed from a catchment can be used to predict the sources of faecal contamination in another catchment with similar landuse features within the same geographical area. However, the representativeness and the stability of the database should be evaluated prior to its application in such investigation.

Animals↗

Population similarity of enterococci and Escherichia coil in surface waters: A predictive tool to trace the sources of fecal contamination.

A biochemical fingerprinting method (the PhPlate system) was used to compare similarities between Escherichia coli and enterococci populations from surface water samples with those found in different animal species during the wet and the dry seasons in order to predict the dominant source(s) of fecal contamination in a local creek. A significant increase in the number and diversity of enterococci was observed in the creek during the wet season. Enterococci population from water samples also showed a higher population similarity with animal species than did E. coli. A higher population similarity was found between both indicator bacteria and animal species during the wet season with highest population similarities found in dogs, horses, cows and kangaroos. In contrast, a low population similarity was found for both fecal indicator bacteria from humans with water samples during the wet and the dry seasons, indicating that humans are not a major source of contamination in the studied creek. The results also indicate that the population similarity analysis of enterococci population has an advantage over E. coli in tracing the possible source(s) of contamination in the studied creek and that population similarity analysis as used in this study can be used to predict the source(s) of fecal contamination in surface waters.

Animals↗

Evidence of septic system failure determined by a bacterial biochemical fingerprinting method.

AIMS: To provide evidence of septic system failure by comparing two faecal indicator bacteria, enterococci and Escherichia coli, from defective septic tanks and adjacent creeks. METHODS AND RESULTS: A biochemical fingerprinting method was used to type and compare enterococci and E. coli strains from 39 septic tanks with creek water samples. Phenotypic diversity of enterococci (0.5 +/- 0.3) and E. coli (0.5 +/- 0.3) in septic tanks were significantly lower than those found in water samples (0.8 +/- 0.1, P < 0.0001 for enterococci and 0.9 +/- 0.1, P < 0.0001 for E. coli). Among 1072 enterococci isolates tested from septic tanks, 203 biochemical phenotypes (BPTs) were found of which 98 BPTs from 33 septic tanks were identical to several water samples. Similarly, among 621 E. coli isolates tested from septic tanks, 159 BPTs were found of which 53 BPTs from 26 septic tanks were also identical to water samples. The number of the latter bacteria was significantly (P = 0.01) higher in water samples collected from downstream compared with that of upstream in the study area. A high similarity between the populations of both indicator bacteria was also found between defective septic tanks and downstream water samples further indicating the contamination of both creeks by defective septic systems. CONCLUSIONS: Biochemical fingerprinting of faecal indicator bacteria is a useful and rapid method to provide direct evidence for septic system failure. Combination of both faecal indicator bacteria (enterococci and E. coli) provides a better judgement of the performance of a septic system. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first to provide direct evidence of septic system failure by identifying the presence of specific bacterial types in septic tanks and surface waters. Based on our findings, we suggest that the performance evaluation of a septic system should be accompanied by direct analysis of faecal indicator bacteria.

Animals↗

Host species-specific metabolic fingerprint database for enterococci and Escherichia coli and its application to identify sources of fecal contamination in surface waters.

A metabolic fingerprint database of enterococci and Escherichia coli from 10 host groups of animals was developed to trace the sources of fecal contamination in surface waters. In all, 526 biochemical phenotypes (BPTs) of enterococci and 530 E. coli BPTs were obtained from 4,057 enterococci and 3,728 E. coli isolates tested. Of these, 231 Enterococcus BPTs and 257 E. coli BPTs were found in multiple host groups. The remaining 295 Enterococcus BPTs and 273 E. coli BPTs were unique to individual host groups. The database was used to trace the sources of fecal contamination in a local creek. The mean diversities (Di) of enterococci (Di = 0.76 +/- 0.05) and E. coli (Di = 0.88 +/- 0.04) were high (maximum 1) in water samples, indicating diverse sources of fecal contamination. Overall, 71% of BPTs of enterococci and 67% of E. coli BPTs from water samples were identified as human and animal sources. Altogether, 248 Enterococcus BPTs and 282 E. coli BPTs were found in water samples. Among enterococci, 26 (10%) BPTs were identical to those of humans and 152 BPTs (61%) were identical to those of animals (animal BPTs). Among E. coli isolates, 36 (13%) BPTs were identical to those of humans and 151 (54%) BPTs were identical to those of animals. Of the animal BPTs, 101 (66%) Enterococcus BPTs and 93 (62%) E. coli BPTs were also unique to individual animal groups. On the basis of these unique Enterococcus BPTs, chickens contributed 14% of contamination, followed by humans (10%), dogs (7%), and horses (6%). For E. coli, humans contributed 13% of contamination, followed by ducks (9%), cattle (7%), and chickens (6%). The developed metabolic fingerprint database was able to distinguish between human and animal sources as well as among animal species in the studied catchment.

Animals↗

Diamond coated dental bur machining of natural and synthetic dental materials.

Diamond coatings are attractive for cutting processes due to their high hardness, low friction coefficient, excellent wear resistance and chemical inertness. The application of diamond coatings on cemented tungsten carbide (WC-Co) burs has been the subject of much attention in recent years in order to improve cutting performance and tool life. WC-Co burs containing 6% Co and 94% WC with an average grain size 1-3 micron were used in this study. In order to improve the adhesion between diamond and the bur it is necessary to etch away the surface Co to prepare it for subsequent diamond growth. Hot filament chemical vapour deposition (H.F.C.V.D.) with a modified vertical filament arrangement has been employed for the deposition of diamond films. Diamond film quality and purity has been characterised using scanning electron microscopy (S.E.M.) and micro-Raman spectroscopy. The performance of diamond coated WC-Co burs, uncoated WC-Co burs, and diamond embedded (sintered) burs have been compared by drilling a series of holes into various materials such as human teeth, and model tooth materials such as borosilicate glass and acrylic. Flank wear has been used to assess the wear rates of the burs when machining natural and synthetic dental materials such as those described above.

Dental Materials↗

Synovial cyst of the hip joint: an unusual cause of a pulsating groin mass.

Synovial cysts of the hip joint occur most frequently in patients with rheumatoid arthritis (1). Despite the increasing frequency of arthroplasty of rheumatoid hips, case reports documenting synovial cysts remain extremely rare. This case report emphasizes the need for the surgeon to include a synovial cyst in the differential diagnosis of a painless groin mass, particularly in patients with rheumatoid arthritis.

Aged↗

Diabetes mellitus is equally frequent in chronic HCV and HBV infection.

OBJECTIVE: To see the association of type 2 diabetes mellitus (Type 2 DM) in patients suffering from chronic HBV or HCV related liver disease. SETTING: Patients were selected from the gastroenterology OPD of the medical research centre, diabetic controls from private diabetes clinic and healthy controls from the blood bank of the hospital. METHODS: Patients with chronic liver disease had HBV, HCV tested using ELISA and blood sugar using a glucometer mostly as a 2 hour post prandial sample. Healthy controls had their sugar and ALT checked while donating blood and HBV, HCV were checked routinely. In diabetic controls, blood sample was taken as sera stored for HBV,HCV and ALT and later tested in batches. A random sugar of > or = 200 mg/dl was taken as diabetes. RESULTS: Of 400 patient with chronic liver disease 302 had HCV and 98 HBV infection. Diabetes was found in 24.5% HCV and 19.4% HBV related cases (not significant). Out of 410 healthy controls 18 were HCV and 17 HBV positive. Diabetes was found in only 1 (5.6%) HCV positive control and none of the HBV positive controls. Of 196 diabetics 10 (5.1%) were HCV positive and none HBV positive. Diabetes was more frequent in patients having liver cirrhosis than in those having chronic hepatitis (P < 0.01). CONCLUSION: Diabetes is equally frequent in both HBV and HCV related disease but is significantly more in those with chronic liver disease than in controls. The pancreatic damage secondary to extrahepatic viral replication appears to be the major cause but genetic factors also need to be explored.

Adult↗

Magnetic resonance lipid signals in rat brain after experimental stroke correlate with neutral lipid accumulation.

Proton magnetic resonance spectroscopy (MRS) signals from lipids in brain have been observed to increase after ischemic brain injury. However, neither the chemical identity nor the cellular location of these lipids has been established. The aim of the present study was to identify the origin of MRS lipid signals in rat brain after temporary (90 min) middle cerebral artery occlusion (MCAO). Fatty acyl proton signals were detected by short-echo one and two dimensional (1)H MRS in superfused brain slices from the infarcted hemisphere 1-5 days after MCAO. The intensities of these signals were strongly correlated with the amount of triacylglyceride and cholesterol ester in lipid extracts from the samples (r(2)=0.96, P<0.05) and were not correlated with the amount of free fatty acids in the tissue. Histological staining of tissue revealed the presence of neutral lipid droplets in infarcted regions. Dual labeling by immunohistochemistry demonstrated that these droplets were localized to microglia/macrophage (OX-42-labeled cells). These results strongly suggest that (1)H MRS lipid signals from brain after stroke arise from microglia/macrophage phagocytosis of cellular membranes.

Animals↗

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in cerebrospinal fluid differ in multiple sclerosis and Devic's neuromyelitis optica.

Matrix metalloproteinases (MMPs) are increased in the CSF of patients with multiple sclerosis. Devic's neuromyelitis optica (DNO) is a demyelinating syndrome that involves the optic nerve and cervical cord but differs pathologically from multiple sclerosis. Therefore, we hypothesized that the type of inflammatory reaction that causes MMPs to be elevated in multiple sclerosis would be absent in patients with DNO. CSF was collected from 23 patients with relapsing-remitting or secondary progressive multiple sclerosis, all of whom were experiencing acute symptoms, from seven patients with DNO, and from seven normal volunteers. Diagnoses were made according to current criteria on the basis of clinical manifestations, imaging results and CSF studies. IgG synthesis was increased in the CSF of multiple sclerosis patients but not in that of DNO patients. Zymography, reverse zymography and ELISA (enzyme-linked immunosorbent assay) were used to measure gelatinase A (MMP-2), gelatinase B (MMP-9) and tissue inhibitors of metalloproteinases (TIMPs). Zymograms showed that multiple sclerosis patients had elevated MMP-9 compared with DNO patients and controls (P: < 0.05). TIMP-1 and TIMP-2 levels were similar in all three groups. We conclude that multiple sclerosis patients have higher MMP-9 levels in the CSF than patients with DNO, which supports the different pathological mechanisms of these diseases.

Humans↗

Cardiovascular complications of weight reduction diets.

Weight reduction diets may reduce the severity of risk factors for coronary heart disease such as diabetes mellitus, hypertension, and dyslipidemia. Several case reports and small studies of patients receiving starvation diets have reported hypotension and sudden cardiac death. Myofibrillar damage was documented in 1 case. Very-low-calorie diets are generally safe and well-tolerated. However, low QRS voltage, QT interval prolongation, and both nonsustained ventricular arrhythmias and sudden cardiac death have been described in subjects treated with such diets. Orthostatic hypotension may complicate very-low-calorie protein diets because of sodium depletion and depressed sympathetic nervous system activity. Bariatric surgery is associated with disproportionately high mortality rates in both the perioperative and postoperative periods.

Adult↗

MR spectroscopy study of dichloroacetate treatment after ischemic stroke.

In a double-blind, placebo-controlled study, we used 1H MR spectroscopy to assess the effect of a single infusion of sodium dichloroacetate on lesion lactate 1 to 5 days after ischemic stroke. Apparent trends toward a reduction in lactate/N-acetyl compound ratios were seen at the higher drug doses employed, and in patients treated in the first 2 days following infarction. Use of spectroscopic measures as endpoints is feasible in acute stroke clinical trials.

Brain Ischemia↗

Neuroleptic malignant syndrome and severe thrombocytopenia: case report and literature review.

We report an unusual case of thrombocytopenia associated with neuroleptic malignant syndrome (NMS). A 31-year-old Black male with a history of hypertension, partial seizures, and schizophrenia developed acute rigidity closely followed by severe hyperpyrexia (temperature 102 degree F), tachypnea, and tachycardia. His home medications at the time of presentation included propanolol 10 mg tid, haloperidol 10 mg bid, sodium valproate 500 mg bid, benztropine 1 mg bid, and haloperidol decanoate 100 mg i.m. every 3 weeks, from another psychiatric facility. Despite vigorous therapy for the hyperthermia, he rapidly developed significant hypoxia requiring mechanical ventilation. A diagnosis of neuroleptic malignant syndrome was made and the patient continued to receive aggressive supportive care. On hospital day 2 his platelet count dropped to 47,000/microl and bottomed out at 36,000/microl by day 3 with other blood cell counts remaining within normal limits. Over the next few days he showed rapid clinical improvement with normalization of his blood chemistries and he was discharged home after 5 days of hospitalization in good condition.

Adult↗

Appropriateness of endotracheal tube size and insertion depth in children undergoing air medical transport.

OBJECTIVES: Guidelines for pediatric endotracheal tube (ETT) size and insertion depth are important in the helicopter EMS (HEMS) setting, where intubated patients are frequently transported by a non-physician flight crew providing protocol-based care in an environment noted for limitations in clinical airway assessment. The objectives of this study were to characterize, in a HEMS pediatric population, the frequency of compliance with guideline-recommended ETT size and insertion depth, and to test for association between guideline noncompliance and subsequent receiving hospital adjustment of ETT size or insertion depth. DESIGN: This retrospective review analyzed 216 consecutive pediatric (age <14) scene and interfacility HEMS transports, of patients intubated before or during HEMS transport, by an urban two-helicopter HEMS service providing protocol-based care with a nurse/paramedic crew configuration. Patients were transported to one of three receiving academic pediatric referral centers. Pediatric Advanced Life Support (PALS) criteria for ETT size and insertion depth were used to assess guideline-appropriateness of pediatric ETTs. Receiving hospital records were reviewed to determine if post-transport ETT size or lipline adjustment were associated with guideline-appropriateness of size and lipline during HEMS transport. Univariate (chi-square and Fisher's exact) and multivariate (logistic regression) statistics were used to assess and control for the following covariates: intubator group (physician, flight crew, ground EMS), transport year, sex, age, transport type (scene versus interfacility), and receiving hospital. For all analyses, statistical significance was set at the 0.05 level. RESULTS: The initial ETT size was within 0.5 mm of guideline-recommended sizes in 178 (83.6%) of the 213 patients for whom this data were available. Inappropriate sized ETTs were nearly always (32 of 35, 91.4%) too small. Compared to initial ETTs placed by ground EMS personnel, initial ETTs placed by flight crew or physicians were more likely to be appropriate as defined by guidelines (P = .008 and .032, respectively). Receiving hospitals changed the ETT size in 18 (8.3% of 216) cases. Receiving hospital ETT size change was more likely with later transport year (P = .018) and less likely in patients over 2 years of age (P = .03); there was no significant association between receiving hospital ETT size change and intubator group (P > .22) or guideline-appropriateness of ETT size (P = 0.94). The initial ETT insertion depth was within 1 cm of the guideline-recommended lipline in 86 (43.2%) of the 199 patients for whom this data were available. Inappropriate liplines were almost always (109 of 113, 96.5%) too deep. Compared to initial ETT liplines determined by ground EMS personnel, initial liplines determined by flight crew (P = .007), but not physician (P = .47) were more likely to be appropriate as defined by guidelines. Receiving hospitals changed the ETT insertion depth in 72 (33.3% of 216) cases. Receiving hospital lipline change was more likely (P = .03) in patients older than 2 years of age, but was not associated with intubator group (P = .75) or lipline guideline-appropriateness (P = .35). CONCLUSIONS: As judged by frequently used guidelines, pediatric ETTs are often too small and commonly inserted too deep. However, this retrospective study, limited by lack of clinical correlation for ETT size and insertion depth, failed to find an association between lack of ETT size or lipline guideline compliance and subsequent ETT adjustment at receiving pediatric centers. This study's findings, which should be confirmed with prospective investigation, cast doubt upon the utility of pediatric ETT size/lipline guidelines as strict clinical or quality assurance tools for use in pediatric airway management.

Age Factors↗

'Catastrophic' antiphospholipid syndrome.

When 'catastrophic' is applied as an adjective to the antiphospholipid syndrome, it implies a characteristic presentation due to predominantly small blood vessel thrombosis leading to rapidly progressive failure of multiple organs and a frequently fatal outcome. We present the case of a 48-year-old woman who presented with the 'catastrophic' antiphospholipid syndrome without previous history of coagulation disorder or connective tissue disease that illustrates the difficulties in diagnosing and managing this disorder. We also review the factors that have been reported to have a role in the development of this condition and show how this case throws light on its pathogenesis.

Anti-Inflammatory Agents↗