We report a case of sciatic nerve entrapment resulting in a patient experiencing pain over the posterior aspect of the knee, simulating a Baker's cyst. Surgical exploration revealed a tight fibrous arch compressing the distal portion of the sciatic nerve, proximal to its bifurcation. Decompression of this entrapment led to complete relief of symptoms. This form of presentation is rare and should be considered as a differential diagnosis when a patient presents with complaints of pain in the back of the knee. Keywords: Sciatic nerve compression, pain in the back of the knee
Heavy metals with high chemical activity from sludge and waste release, agriculture, and
mining activity are a major concern. They should be carefully managed before reaching the
main water bodies. Excessive exposure to heavy metal may cause toxic effect to any types of
organism from the biomolecular to the physiological level, and ultimately cause death. Monitoring is the best technique to ensure the safety of our environment before a rehabilitation is
needed. Nowadays, enzyme-based biosensors are utilised in biomonitoring programmes as
this technique allows for a real-time detection and rapid result. It is also inexpensive and easy
to handle. Enzyme-based biosensors are an alternative for the preliminary screening of
contamination before a secondary screening is performed using high-performance technology.
This review highlights the current knowledge on enzyme-based biosensors, focusing on
cholinesterase for toxic metal detection in the environment.
A novel molybdate-reducing bacterium, tentatively identified as Klebsiella sp. strain hkeem and based on partial 16s rDNA gene sequencing and phylogenetic analysis, has been isolated. Strain hkeem produced 3 times more molybdenum blue than Serratia sp. strain Dr.Y8; the most potent Mo-reducing bacterium isolated to date. Molybdate was optimally reduced to molybdenum blue using 4.5 mM phosphate, 80 mM molybdate and using 1% (w/v) fructose as a carbon source. Molybdate reduction was optimum at 30 °C and at pH 7.3. The molybdenum blue produced from cellular reduction exhibited absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of electron transport system such as antimycin A, rotenone, sodium azide, and potassium cyanide did not inhibit the molybdenum-reducing enzyme. Mercury, silver, and copper at 1 ppm inhibited molybdenum blue formation in whole cells of strain hkeem.
Arsenic is a toxic metalloid which is widely distributed in nature. It is normally present as arsenate under oxic conditions while arsenite is predominant under reducing condition. The major discharges of arsenic in the environment are mainly due to natural sources such as aquifers and anthropogenic sources. It is known that arsenite salts are more toxic than arsenate as it binds with vicinal thiols in pyruvate dehydrogenase while arsenate inhibits the oxidative phosphorylation process. The common mechanisms for arsenic detoxification are uptaken by phosphate transporters, aquaglyceroporins, and active extrusion system and reduced by arsenate reductases via dissimilatory reduction mechanism. Some species of autotrophic and heterotrophic microorganisms use arsenic oxyanions for their regeneration of energy. Certain species of microorganisms are able to use arsenate as their nutrient in respiratory process. Detoxification operons are a common form of arsenic resistance in microorganisms. Hence, the use of bioremediation could be an effective and economic way to reduce this pollutant from the environment.
Phaleria macrocarpa (Scheff.) Boerl (Thymelaceae) originates from Papua Island, Indonesia and grows in tropical areas. The different parts of the fruit of P. macrocarpa were evaluated for antioxidant, anti-inflammatory, and cytotoxic activities.
As well as for chemical and environmental reasons, acrylamide is widely used in many industrial applications. Due to its carcinogenicity and toxicity, its discharge into the environment causes adverse effects on humans and ecology alike. In this study, a novel acrylamide-degrading yeast has been isolated. The isolate was identified as Rhodotorula sp. strain MBH23 using ITS rRNA analysis. The results showed that the best carbon source for growth was glucose at 1.0% (w/v). The optimum acrylamide concentration, being a nitrogen source for cellular growth, was at 500 mg l(-1). The highest tolerable concentration of acrylamide was 1500 mg l(-1) whereas growth was completely inhibited at 2000 mg l(-1). At 500 mg l(-1), the strain MBH completely degraded acrylamide on day 5. Acrylic acid as a metabolite was detected in the media. Strain MBH23 grew well between pH 6.0 and 8.0 and between 27 and 30 °C. Amides such as 2-chloroacetamide, methacrylamide, nicotinamide, acrylamide, acetamide, and propionamide supported growth. Toxic heavy metals such as mercury, chromium, and cadmium inhibited growth on acrylamide.
In this work, we report on the isolation of a phenol-degrading Rhodococcus sp. with a high tolerance towards phenol. The isolate was identified as Rhodococcus sp. strain AQ5NOL 2, based on 16S rDNA analysis. The strain degraded phenol using the meta pathway, a trait shared by many phenol-degraders. In addition to phenol biodegradation, the strain was also capable of degrading diesel. Strain AQ5NOL 2 exhibited a broad optimum temperature for growth on phenol at between 20 °C and 35 °C. The best nitrogen sources were ammonium sulphate, glycine or phenylalanine, followed by proline, nitrate, leucine, and alanine (in decreasing efficiency). Strain AQ5NOL 2 showed a high tolerance and degradation capacity of phenol, for it was able to register growth in the presence of 2000 mg l(-1) phenol. The growth of this strain on phenol as sole carbon and energy source were modeled using Haldane kinetics with a maximal specific growth rate (μ(max)) of 0.1102 hr(-1), a half-saturation constant (K(s) ) of 99.03 mg l(-1) or 1.05 mmol l(-1), and a substrate inhibition constant (K(i)) of 354 mg l(-1) or 3.76 mmol l(-1). Aside from phenol, the strain could utilize diesel, 2,4-dinitrophenol and ρ-cresol as carbon sources for growth. Strain AQ5NOL 2 exhibited inhibition of phenol degradation by Zn(2+), Cu(2+), Cr(6+), Ag(+) and Hg(2+) at 1 mg l(-1).
Extensive use of metals in various industrial applications has caused substantial environmental pollution. Molybdenum-reducing bacteria isolated from soils can be used to remove molybdenum from contaminated environments. In this work we have isolated a local bacterium with the capability to reduce soluble molybdate to the insoluble molybdenum blue. We studied several factors that would optimize molybdate reduction. Electron donor sources such as glucose, sucrose, lactose, maltose and fructose (in decreasing efficiency) supported molybdate reduction after 24 h of incubation with optimum glucose concentration for molybdate reduction at 1.5% (w/v). The optimum pH, phosphate and molybdate concentrations, and temperature for molybdate reduction were pH 6.5, 5.0, 25 to 50 mM and 37 degrees C, respectively. The Mo-blue produced by cellular reduction exhibited a unique absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. Metal ions such as chromium, cadmium, copper, silver and mercury caused approximately 73, 71, 81, 77 and 78% inhibition of the molybdenum-reducing activity, respectively. All of the respiratory inhibitors tested namely rotenone, azide, cyanide and antimycin A did not show any inhibition to the molybdenum-reducing activity suggesting components of the electron transport system are not responsible for the reducing activity. The isolate was tentatively identified as Enterobacter sp. strain Dr.Y13 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny.
Phaleria macrocarpa (Scheff.) Boerl (Thymelaceae) is commonly known as 'Crown of God', 'Mahkota Dewa', and 'Pau'. It originates from Papua Island, Indonesia and it grows in tropical areas. Empirically, it is potent in treating the hypertensive, diabetic, cancer and diuretic patients. It has a long history of ethnopharmacological usage, and the lack of information about its biological activities led us to investigate the possible biological activities by characterisation of flavonoids and antimicrobial activity of various part of P. macrocarpa against pathogenic bacteria and fungi. The results showed that kaempferol, myricetin, naringin, and rutin were the major flavonoids present in the pericarp while naringin and quercetin were found in the mesocarp and seed. Furthermore, the antibacterial activity of different parts of P. macrocarpa fruit showed a weak ability to moderate antibacterial activity against pathogenic tested bacteria (inhibition range: 0.93-2.17 cm) at concentration of 0.3 mg/disc. The anti fungi activity was only found in seed extract against Aspergillus niger (1.87 cm) at concentration of 0.3 mg/well. From the results obtained, P. macrocarpa fruit could be considered as a natural antimicrobial source due to the presence of flavonoid compounds.
A local molybdenum-reducing bacterium was isolated and tentatively identified as Acinetobacter calcoaceticus strain Dr.Y12 based on carbon utilization profiles using Biolog GN plates and 16S rDNA comparative analysis. Molybdate reduction was optimized under conditions of low dissolved oxygen (37 degrees C and pH 6.5). Of the electron donors tested, glucose, fructose, maltose and sucrose supported molybdate reduction after 1 d of incubation, glucose and fructose supporting the highest Mo-blue production. Optimum Mo-blue production was reached at 20 mmol/L molybdate and 5 mmol/L phosphate; increasing the phosphate concentrations inhibited the production. An increase in an overall absorption profiles, especially at peak maximum at 865 nm and the shoulder at 700 nm, was observed in direct correlation with the increased in Mo-blue amounts. Metal ions, such as chromium, cadmium, copper, mercury and lead (2 mmol/L final concentration) caused approximately 88, 53, 80, 100, and 20 % inhibition, respectively. Respiratory inhibitors, such as antimycin A, rotenone, sodium azide and cyanide showed in this bacterium no inhibition of the Mo-blue production, suggesting that the electron transport system is not a site of molybdate reduction.
An inhibitive assay of insecticides using Acetylcholinesterase (AChE) from the local fish Clarias batrachus is reported. AChE was assayed according to the modified method of Ellman. Screening of insecticide and heavy metals showed that carbofuran and carbaryl strongly inhibited C. batrachus AChE. The inhibition concentration (IC) IC50 values (and the 95% confidence interval) for both carbofuran and carbaryl inhibition on C. batrachus AChE at 6.66 (5.97-7.52) and 130.00 (119.3-142.5) microg l(-1), respectively was within the IC50 range of Electrophorus electricus at 6.20 (6.03-6.39) and 133.01 (122.40-145.50) microg l(-1), respectively and were much lower than bovine AChE at 20.94 (19.53-22.58) and 418.80 (390.60-451.60) microg l(-1), respectively. The results showed that C. batrachus have the potential to be used as a cheaper and more readily available source of AChE than other more commercially available sources.
A stab-culture method was adapted to screen for azo dyes-decolorizing bacteria from soil and water samples. Decolorized azo dye in the lower portion of the solid media indicates the presence of anaerobic azo dyes-decolorizing bacteria, while aerobic decolorizing bacteria decolorizes the surface portion of the solid media. Of twenty soil samples tested, one soil sample shows positive results for the decolourisation of two azo dyes; Biebrich scarlet (BS) and Direct blue 71 (DB) under anaerobic conditions. A gram negative and oxidase negative bacterial isolate was found to be the principal azo dyes degrader The isolate was identified by using the Biolog identification system as Serratia marcescens.
Surgical site infection associated with surgical instruments has always been a factor in delaying post-operative recovery of patients. The evolution in surface modification of surgical instruments can be a potential choice to overcome the nosocomial infection mainly caused by bacterial populations such as Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. A study was, therefore, conducted characterising the morphology, hydrophobicity, adhesion strength, phase, Nano-hardness, surface chemistry, antimicrobial and biocompatibility of SS 316L steel deposited with a Nano-composite layer of Silver (Ag) and Tantalum oxide (Ta2O5) using physical vapour deposition magnetron sputtering. The adhesion strength of Ag/AgTa2O5 coating on SS 316L and treated at 250-850 °C of thermal treatment was evaluated using micro-scratch. The Ag/Ag-Ta2O5-400 °C was shown a 154% improvement in adhesion strength on SS 316L when compared with as-sputtered layer or Ag/Ag-Ta2O5-250, 550, 700 and 850 °C. The FESEM, XPS, and XRD indicated the segregation of Ag on the surface of SS 316L after the crystallization. Wettability and Nano-indentation tests demonstrated an increase in hydrophobicity (77.3 ± 0.3°) and Nano-hardness (1.12 ± 0.43 GPa) when compared with as-sputtered layer, after the 400 °C of thermal treatment. The antibacterial performance on Ag/Ag-Ta2O5-400 °C indicated a significant zone of inhibition to Staphylococcus aureus (A-axis: 16.33 ± 0.58 mm; B-axis: 25.67 ± 0.58 mm, p
Luminescence-based assays for toxicants such as Microtox, ToxAlert, and Biotox have been used extensively worldwide. However, the use of these assays in near real time conditions is limited due to nonoptimal assay temperature for the tropical climate. An isolate that exhibits a high luminescence activity in a broad range of temperatures was successfully isolated from the mackerel, Rastrelliger kanagurta. This isolate was tentatively identified as Photobacterium sp. strain MIE, based on partial 16S rDNA molecular phylogeny. Optimum conditions that support high bioluminescence activity occurred between 24 and 30°C, with pH 5.5 to 7.5, 10 to 20 g/L of sodium chloride, 30 to 50 g/L of tryptone, and 4 g/L of glycerol as the carbon source. Assessment of near real time capability of this bacterial system, Xenoassay light to monitor heavy metals from a contaminated river running through the Juru River Basin shows near real time capability with assaying time of less than 30 minutes per samples. Samples returned to the lab were tested with a standard Microtox assay using Vibrio fishceri. Similar results were obtained to Xenoassay light that show temporal variation of copper concentration. Thus, this strain is suitable for near real time river monitoring of toxicants especially in the tropics.
The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C). A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a V max for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent K m for NADH was 0.79 mM. At 5 mM NADH, the apparent V max and apparent K m values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (k cat/K m ) of the Mo-reducing enzyme was 5.47 M(-1) s(-1). The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction.
A diesel-degrading bacterium was isolated from a diesel-contaminated site in Selangor, Malaysia. The isolate was tentatively identified as Acinetobacter sp. strain DRY12 based on partial 16S rDNA molecular phylogeny and Biolog GN microplate panels and Microlog database. Optimum growth occurred from 3 to 5% diesel and the strain was able to tolerate as high as 8% diesel. The optimal pH that supported growth of the bacterium was between pH 7.5 to 8.0. The isolate exhibited optimal growth in between 30 and 35 degrees C. The best nitrogen source was potassium nitrate (between 0.6 and 0.9% (w/v)) followed by ammonium chloride, sodium nitrite and ammonium sulphate in descending order. An almost complete removal of diesel components was seen from the reduction in hydrocarbon peaks observed using Solid Phase Microextraction Gas Chromatography analysis after 10 days of incubation. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibiting growth with a correlation coefficient value of 0.97. The maximum growth rate- micromax was 0.039 hr(-1) while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.387% and 4.46%, respectively. MATH assays showed that 75% of the bacterium was found in the hexadecane phase indicating that the bacterium was hydrophobic. The characteristics of this bacterium make it useful for bioremediation works in the Tropics.
A survey of ticks and other ectoparasites was carried out during a national biodiversity scientific expedition at Ulu Muda Forest Reserve, Kedah, Malaysia from 23-29 March 2003. A total of 161 animals comprising 20 species of birds, 16 species of bats, six species of non-volant small mammals and 12 species of reptiles were examined for ticks and other ectoparasites. From these animals, nine species in five genera of ticks, 10 species in two families of Mesostigmatid mites and five species of chiggers were collected. Three of the ectoparasitic species found, Dermacentor auratus, Ixodes granulatus and Leptotrombidium deliense are of known public health importance. This survey produced the first list of ticks and other ectoparasites in the forest reserve and the third study of ectoparasites in Kedah. Fourteen species of these ectoparasites are new locality records.
Molybdenum-reducing activity in the heterotrophic bacteria is a phenomenon that has been reported for more than 100 years. In the presence of molybdenum in the growth media, bacterial colonies turn to blue. The enzyme(s) responsible for the reduction of molybdenum to molybdenum blue in these bacteria has never been purified. In our quest to purify the molybdenum-reducing enzyme, we have devised a better substrate for the enzyme activity using laboratory-prepared phosphomolybdate instead of the commercial 12-phosphomolybdate we developed previously. Using laboratory-prepared phosphomolybdate, the highest activity is given by 10:4-phosphomolybdate. The apparent Michaelis constant, Km for the laboratory-prepared 10:4-phosphomolybdate is 2.56 +/- 0.25 mM (arbitrary concentration), whereas the apparent V(max) is 99.4 +/- 2.85 nmol Mo-blue min(-1) mg(-1) protein. The apparent Michaelis constant or Km for NADH as the electron donor is 1.38 +/- 0.09 mM, whereas the apparent V(max) is 102.6 +/- 1.73 nmol Mo-blue min(-1) mg(-l) protein. The apparent Km and V(max) for another electron donor, NADPH, is 1.43 +/- 0.10 mM and 57.16 +/- 1.01 nmol Mo-blue min(-1) mg(-1) protein, respectively, using the same batch of molybdenum-reducing enzyme. The apparent V(max) obtained for NADH and 10:4-phosphomolybdate is approximately 13 times better than 12-phoshomolybdate using the same batch of enzyme, and hence, the laboratory-prepared phosphomolybdate is a much better substrate than 12-phoshomolybdate. In addition, 10:4-phosphomolybdate can be routinely prepared from phosphate and molybdate, two common chemicals in the laboratory.
A heavy-metal assay has been developed using bromelain, a protease. The enzyme is assayed using casein as a substrate with Coomassie dye to track completion of hydrolysis of casein. In the absence of inhibitors, casein is hydrolysed to completion, and the solution is brown. In the presence of metal ions such as Hg2+ and Cu2+, the hydrolysis of casein is inhibited, and the solution remains blue. Exclusion of sulfhydryl protective agent and ethylenediaminetetraacetic in the original assay improved sensitivity to heavy metals several fold. The assay is sensitive to Hg2+ and Cu2+, exhibiting a dose-response curve with an IC50 of 0.15 mg 1(-1) for Hg2+ and a one-phase binding curve with an IC50 of 0.23 mg 1(-1) for Cu2+. The IC50 value for Hg2+ is found to be lower to several other assays such as immobilized urease and papain assay, whilst the IC50 value for Cu2+ is lower than immobilized urease, 15-min Microtox, and rainbow trout.