Effect of virtual reality training on standing balance in individuals with incomplete spinal cord injury

Recovery of balance ability during standing is one of the primary and essential aims of rehabilitative programs in individuals with incomplete spinal cord injury (iSCI). A sample of ten participants (mean age: 35.7 years, range: 25-63 years) with traumatic or non-traumatic iSCI (AIS grade C or D) and were able to stand with or without the support of an assistive device for a minimum of 2 min were recruited from the rehabilitation department of the Indian Spinal Injuries Centre, New Delhi, India. The participants received Virtual Reality (VR) based balance training for one hour, three times a week for four weeks on the Nintendo Wii gaming console. Participants were assessed three times: pre-intervention, post-intervention and follow-up assessment for the total ellipse area (TEA), total sway perimeter (TSP), sway range (anterior-posterior/medio-lateral (AP/ML)) and limits of stability (LOS). At post-intervention assessment, significant increases in comparison with pre-intervention scores was found in LOS (P=0.00), TEA with eyes open (EO) (P=0.00) and eyes closed (EC) (P=0.00), TSP with EO (P=0.00) and EC (P=0.00), sway range in AP direction (SD-AP) with EO (P=0.01) and EC (P=0.02) and sway range in ML direction (SD-ML) with EO (P=0.02) and EC (P=0.01). At follow-up assessment, a significant improvement in comparison to post intervention scores was found in TEA measured both in EO (P=0.01) and EC conditions (P=0.02), TSP measured with EO (P=0.01) and SD-ML both with EO (P=0.04) and EC (P=0.01). No significant changes were found in LOS (P=0.89), TSP measured with EC (P=0.38) and SD-AP both with EO (P=0.50) and EC (P=1). However, significant improvement was seen on comparing follow-up assessment scores with pre-intervention scores for all variables, such as LOS (P=0.00), TEA in EO (P=0.00) and EC (P=0.00), TSP with EO (P=0.00) and EC (P=0.00), SD-AP with EO (P=0.01) and EC (P=0.02) and SD-ML with EO (P=0.01) and EC (P=0.00). VR-based balance training intervention was able to elicit improvements in balance ability and maintain it during follow-up despite a small training dosage suggesting that it is a promising intervention for standing balance rehabilitation among individuals with iSCI. The VR-based balance training challenges elements of balance, which physical therapists may want to consider when designing a comprehensive rehabilitation program.

Clinical Trials Registry-India: CTRI/2018/12/016814.

Antibiotic prophylaxis in clean-contaminated head and neck cases with microvascular free flap reconstruction: A systematic review and meta-analysis

BACKGROUND

Optimal antibiotic prophylaxis duration in head and neck clean-contaminated free-flap cases is unknown.

METHODS

A systematic review/meta-analysis was conducted using PubMed/MEDLINE, Cochrane Library, Web-of-Science, and Scopus databases.

RESULTS

Of the 3755 searched articles, 5 articles were included for a total of 861 patients. The recipient surgical site infection risk was significantly higher in patients receiving prophylactic antibiotics for ≤24 hours compared to >24 hours (relative risk [RR] 1.56; 95% confidence interval [CI] 1.13-2.14). In the post hoc multivariate analysis based on available individual-level data on 697 patients from 3 studies, the risk of surgical site infection for ≤24 hours versus >24 hours was not significant after adjusting for antibiotic type (RR 1.09; 95% CI 0.78-1.55). When compared to ampicillin-sulbactam, patients who received clindamycin prophylaxis had an increased likelihood of recipient surgical site infection (RR 2.85; 95% CI 1.95-4.17).

CONCLUSION

Less than or equal to 24 hours of antibiotic prophylaxis in head and neck clean-contaminated free-flap is likely sufficient but a strong conclusion remains elusive. Clindamycin prophylaxis increases the risk of recipient surgical site infection. Further prospective trials are necessary to clarify.

Auricular Split-Thickness Skin Graft for Ear Canal Coverage

Split-thickness skin graft (STSG) continues to be the preferred means of external auditory canal (EAC) reconstruction. We thus sought to describe our experience using skin from the posterior aspect of the auricle (SPAA) as a donor site in EAC reconstruction. Grafts were, on average, 5 × 10 mm in size and obtained with a No. 10 blade after tumescence injection. The cases of 39 patients who underwent 41 procedures were retrospectively reviewed. Of the 38 patients with both 3- and 6-month follow-ups, no postoperative stenosis or bony exposure occurred. STSG from the SPAA can be a good option in EAC reconstruction. Total EAC/tympanic membrane coverage can be obtained with STSG from the SPAA.

Plant Pathogenic Microbial Communication Affected by Elevated Temperature in Pectobacterium carotovorum subsp. carotovorum

Gram-negative plant pathogenic bacteria regulate specific gene expression in a population density-dependent manner by sensing level of Acyl-Homoserine Lactone (HSL) molecules which they produce and liberate to the environment, called Quorum Sensing (QS). The production of virulence factors (extracellular enzyme viz. cellulase, pectinase, etc.) in Pectobacterium carotovorum subsp. carotovorum (Pcc) is under strong regulation of QS. The QS signal molecule, N-(3-oxohexanoyl)-L-Homoserine Lactone (OHHL) was found as the central regulatory system for the virulence factor production in Pcc and is also under strict regulation of external environmental temperature. Under seven different incubation temperatures (24, 26, 28, 30, 33, 35, and 37 °C) in laboratory condition, highest amount of OHHL (804 violacein unit) and highest (79 %) Disease Severity Index (DSI) were measured at 33 °C. The OHHL production kinetics showed accumulation of highest concentration of OHHL at late log phase of the growth but diminution in the concentration occurred during stationary phase onwards to death phase. At higher temperature (35 and 37 °C) exposure, OHHL was not at detectable range. The effect of temperature on virulence factor production is the concomitant effect of HSL production and degradation which justifies less disease severity index in cross-inoculated tomato fruits incubated at 35 and 37 °C. The nondetection of the OHHL in the elevated temperature may because of degradation as these signal molecules are quite sensitive and prone to get degraded under different physical factors. This result provides the rationale behind the highest disease severity up to certain elevated temperature and leaves opportunities for investigation on mutation, co-evolution of superior plant pathogen with more stable HSL signals-mediated pathogenesis under global warming context.

Interspinous device versus laminectomy for lumbar spinal stenosis: a comparative effectiveness study

BACKGROUND CONTEXT

Currently no studies directly compare effectiveness between interspinous devices (IDs) and laminectomy in lumbar spinal stenosis (LSS) patients.

PURPOSE

To compare reoperations, complications, and costs between LSS patients undergoing ID placement versus laminectomy.

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

The MarketScan database (2007-2009) was queried for adults with LSS undergoing ID placement as a primary inpatient procedure.

OUTCOME MEASURES

Reoperation rates, complication rates, and costs.

METHODS

Each ID patient was matched with a laminectomy patient using propensity score matching. Reoperations, complications, and costs were analyzed in patients with at least 18 months postoperative follow-up. The authors did not receive funding from any external sources for this study.

RESULTS

Among 498 inpatients that underwent ID placement between 2007 and 2009; the average age was 73 years. The cumulative reoperation rates after ID at 12 and 18 months were 21% and 23%, respectively. The average inpatient hospitalization lasted 1.6 days with an associated cost of $17,432. Two propensity-matched cohorts of 174 patients that had undergone ID versus laminectomy were analyzed. Longer length of stay was observed in the laminectomy cohort (2.5 days vs. 1.6 days, p<.0001), whereas ID patients accrued higher costs at index hospitalization ($17,674 vs. $12,670, p=.0001). Index hospitalization (7.5% vs. 3.5%, p=.099) and 90-day (9.2% vs. 3.5%, p=.028) complications were higher in the laminectomy cohort compared with the ID cohort. The ID patients had significantly higher reoperation rates than laminectomy patients at 12 months follow-up (12.6% vs. 5.8%, p=.026) and incurred higher cumulative costs than laminectomy patients at 12 months follow-up ($39,173 vs. $34,324, p=.289).

CONCLUSIONS

Twelve-month reoperation rates and index hospitalization costs were significantly higher among patients who underwent ID compared with laminectomy for LSS.

Perceived facilitators and barriers to physical activity for rural youth: an exploratory study using photovoice

INTRODUCTION

Decreasing physical activity levels, particularly among youth, continue to be a prominent health concern in Canada, and youth living in rural areas may encounter unique facilitators and barriers to physical activity. In addition, current research suggests that overweight and obesity rates are higher for youth in some rural areas compared with urban areas. The goal of this study was to identify the perceived facilitators and barriers to physical activity for a selected sample of rural youth at a rural secondary school in south-western Ontario and examine how rural barriers and facilitators affect rural youth physical activity. Current Canadian literature addresses rural youth physical activity in a very limited fashion. Thus, the goal of this research was to provide important insights into physical activity for rural youth.

METHOD

Nine participants aged 13 to 18 years completed the study using the photovoice methodology and method. Photovoice is a relatively new method for health research that adopts an innovative approach whereby participants use cameras to document their perceived health realities. In photovoice the images and words from the life experiences of participants create the basis for discussion. Participants had 2 weeks to take photographs. After 2 weeks the cameras and logbooks were retrieved, the photographs were developed, and a one-on-one interview was held with each participant. The interviews focused on participants' explanations of their photographs and their relevance to physical activity.

RESULTS

Analysis of the pictorial, narrative, and logbook data provided by participants revealed 12 themes as facilitators and barriers to physical activity. Some of the themes relate to facilitators (eg early exposure to activities), some to barriers (eg lack of opportunities close to home), and some themes represent both a facilitator and a barrier (eg competitiveness, family support, and peer interests). The findings of this study may assist community stakeholders, school officials, and parents to better support the physical activity needs of rural youth.

CONCLUSIONS

Physical activity rates continue to decline and to be a major health concern for Canadian youth. Thus, it is becoming increasingly important to understand physical activity from the perspective of rural youth. Implications of this information for rural communities, rural schools, and rural residents are significant. These implications and recommendations may help facilitate increased participation in physical activity for rural youth by providing them, and their families and communities, with enhanced opportunities and resources to engage in physical activity. Further research is clearly indicated.

Release kinetics of controlled release formulations of thiamethoxam employing nano-ranged amphiphilic PEG and diacid based block polymers in soil

Amphiphilic copolymers, synthesized from poly(ethylene glycols) and various aliphatic and aromatic diacids, which self-assemble into nanomicellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of thiamethoxam (3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine) using encapsulation technique Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of thiamethoxam, released in sandy loam soil from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The time taken for release of 50 % of thiamethoxam ranged from 3.56 to 6.07 days for the CR formulations. Although the diffusion exponent (n value) of thiamethoxam in soil ranged from 0.532 to 0.881 in the tested formulations showing non-Fickian transport. These CR formulations may be used in safer, effective and economic crop protection.

Development of controlled release formulations of imidacloprid employing novel nano-ranged amphiphilic polymers

Amphiphilic copolymers, synthesized from poly (ethylene glycols) and various aliphatic diacids, which self assemble into nano-micellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of imidacloprid [1-(6 chloro-3-pyridinyl methyl)-N-nitro imidazolidin-2-ylideneamine] using encapsulation technique. High solubilisation power and low critical micelle concentration (CMC) of these amphiphilic polymers may increase the efficacy of formulations. Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of imidacloprid release in water from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The diffusion exponent (n value) of imidacloprid, in water ranged from 0.22 to 0.37 in the tested formulations. While the time taken for release of 50 % of imidacloprid ranged from 2.32 to 9.31 days for the CR formulations. The developed CR formulations can be used for efficient pest management in different crops.

Residue and bio-efficacy evaluation of controlled release formulations of imidacloprid against pests in soybean (Glycine max)

Controlled release (CR) formulations of imidacloprid (1-(6 chloro-3-pyridinyl methyl)-N- nitro imidazolidin-2- ylideneamine) were prepared using novel amphiphilic polymers synthesized from polyethylene glycol and aliphatic diacids employing encapsulation technique. The bioefficacy of the prepared CR formulations was evaluated against major pests of soybean, namely stem fly, Melanagromyza sojae Zehntmer and white fly, Bemisia tabaci Gennadius along with a commercial formulation at the experimental farm of Indian Agricultural Research Institute (IARI), New Delhi during kharif 2009 and 2010. Most of the CR formulations of imidacloprid gave significantly better control of the pests compare to its commercial formulations, however the CR formulations, Poly [poly (oxyethylene-1000)-oxy suberoyl] amphiphilic polymer based formulation performed better over others for controlling of both stem fly incidence and Yellow Mosaic Virus (YMV) infestation transmitted by white fly. Some of the developed CR formulations recorded higher yield over commercial formulation and control. Nodulation pattern of soybean was not affected due to treatment of CR and commercial formulations of imidacloprid. Also the residues of imidacloprid in seed and soil at harvest were not detectable for both CR and commercial formulations.

Variation in intubation decisions for patients with chronic obstructive pulmonary disease in one critical care network

BACKGROUND

Anecdotal evidence suggests variation in intubation decisions for chronic obstructive pulmonary disease (COPD) patients with respiratory failure, but little is known about the extent of or reasons for this variability.

AIM

To describe clinician decision-making for patients with exacerbations of COPD considered for intubation.

DESIGN

Telephone simulation study.

METHODS

Consultants responsible for COPD admissions in the Heart of England Critical Care network were asked to decide whether or not to admit three patients with COPD to ICU on the basis of information conveyed over the telephone. Consultants were also asked to predict patients survival in ICU hospital and at 180 days on the assumption that the patient did receive ICU care.

RESULTS

Of the 120 consultants, 98 (82%) took part; 89% would admit patient 1, 64% patient 2, and 40% patient 3. The prediction of survival if ICU admission had occurred differed significantly between admitters and non-admitters. Mean predicted post-ICU hospital survival for patient 1 was 46% (95%CI 43-49) for admitters, and 13% (95%CI 6-19) for non-admitters (p < 0.001). The respective figures for patient 2 were 38% (95%CI 34-42) vs. 12% (95%CI 8-15) (p < 0.001), and for patient 3, 28% (95%CI 24-33) vs. 13% (95%CI 10-16) (p < 0.001). For a housebound COPD patient in their mid 70s, the mean (SD) threshold of predicted hospital survival below which consultants would recommend not admitting to ICU was 22% (13.2%).

CONCLUSIONS

Consultants differed markedly in their admitting decisions about identical patients. Objective outcome prediction models might improve equity in ICU bed use for patients with COPD.

Some furfural derivatives as nitrification inhibitors

Three series of furfural derivatives, namely N-O-furfural oxime ethers, furfural Schiff bases (furfurylidene anilines), and furfural chalcones, have been synthesized and evaluated for nitrification inhibition activity in laboratory incubation studies in typic Ustocrept soil. Furfural oxime ethers and furfural Schiff bases showed potential activity, but furfural chalcones were only mildly active. N-O-ethyl furfural oxime among the oxime ethers, and furfurylidine-4-chloroaniline among the furfural Schiff bases, performed the best. These two compounds showed more than 50% nitrification inhibition on the 45th day at 5% dose as compared to 73% inhibition by nitrapyrin. Activity of furfural oxime ethers decreased with an increase in carbon atoms in the N-O-alkyl side chain. Introduction of a chlorine atom in the phenyl ring of furfurylidene anilines increased the persistence of their activity. N-O-Ethyl furfural oxime and furfurylidine-4-chloroaniline coated urea performed at par with their application in solution form. Ethyl and N-O-isopropyl oxime, as well as chloro- and nitro- substituted Schiff bases, did not reveal any phytotoxicity (adverse effect on germination) on chickpea seeds (Cicer arietinum) even at the highest dose (40 ppm, soil basis).

Insect growth inhibition, antifeedant and antifungal activity of compounds isolated/derived from Zingiber officinale Roscoe (ginger) rhizomes

Fresh rhizomes of Zingiber officinale (ginger), when subjected to steam distillation, yielded ginger oil in which curcumene was found to be the major constituent. The thermally labile zingiberene-rich fraction was obtained from its diethyl ether extract. Column chromatography of ginger oleoresin furnished a fraction from which [6]-gingerol was obtained by preparative TLC. Naturally occurring [6]-dehydroshogaol was synthesised following condensation of dehydrozingerone with hexanal, whereas zingerone and 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)butane were obtained by hydrogenation of dehydrozingerone with 10% Pd/C. The structures of the compounds were established by 1H NMR, 13C NMR and mass (EI-MS and ES-MS) spectral analysis. The test compounds exhibited moderate insect growth regulatory (IGR) and antifeedant activity against Spilosoma obliqua, and significant antifungal activity against Rhizoctonia solani. Among the various compounds, [6]-dehydroshogaol exhibited maximum IGR activity (EC50 3.55 mg ml-1), while dehydrozingerone imparted maximum antifungal activity (EC50 86.49 mg litre-1).

Prolonged clinical and histologic effects from CO2 laser resurfacing of atrophic acne scars

BACKGROUND

The recent development of high-energy pulsed CO2 lasers that minimize thermal injury to uninvolved adjacent structures has revolutionized the manner in which atrophic facial scars are recontoured. Significant improvement of atrophic scars with laser resurfacing has clearly been demonstrated; however, the exact timing for assessment of skin for further treatment has varied due to the unknown amount of time needed after laser scar resurfacing to effect maximal collagen formation and remodeling.

OBJECTIVE

The aim of this study was to determine the immediate and long-term (12-18 months) histologic and clinical effects of atrophic acne scars after CO2 laser resurfacing in order to provide physician guidelines for postoperative clinical assessment for retreatment.

METHODS

Sixty patients (50 women, 10 men, mean age 38 years, skin types I-V) with moderate to severe atrophic facial scars were evaluated. Nineteen patients received regional cheek treatment and 41 patients received full-face resurfacing with a high-energy pulsed CO2 laser. Independent clinical assessments of treated scars were performed at 1, 6, 12, and 18 months and blinded histologic analyses were made of skin biopsies immediately prior to and after laser resurfacing, and at 1, 6, 12, and 18 months postoperatively in six patients.

RESULTS

Significant immediate and prolonged clinical improvement in skin tone, texture, and appearance of CO2 laser-irradiated scars was seen in all patients. Average clinical improvement scores were 2.22 (69%) at 1 month, 2.1 (67%) at 6 months, 2.37 (73%) at 12 months, and 2.5 (75%) at 18 months. Continued collagenesis and subsequent dermal remodeling were observed on histologic examination of biopsied tissue up to 18 months after surgery.

CONCLUSION

Continued clinical improvement was observed as long as 18 months after CO2 laser resurfacing of atrophic scars, with an 11% increase in improvement observed between 6 and 18 months postoperatively. We propose that a longer postoperative interval (12-18 months) prior to assessment for re-treatment be advocated in order to permit optimal tissue recovery and an opportunity for collagen remodeling.

Cutaneous CO2 laser resurfacing infection rate with and without prophylactic antibiotics

BACKGROUND

Cutaneous laser resurfacing is a well-accepted modality, with excellent clinical outcomes and low morbidity rates, for the treatment of a variety of epidermal and dermal lesions. The use of antibiotic prophylaxis continues to be an area of controversy, with laser practitioners divided in their approach.

OBJECTIVE

To identify the rate of postoperative bacterial infection following full-face carbon dioxide (CO2) laser resurfacing with and without antibiotic prophylaxis.

METHODS

A retrospective chart review of 133 consecutive patients following full-face CO2 laser resurfacing was performed. The rate, severity, duration, and subsequent treatment of bacterial infections observed in four treatment categories were recorded: (1) no antibiotic prophylaxis; (2) intraoperative single-dose intravenous cephalexin (1 g); (3) postoperative oral azithromycin (1.5 g over 5 days); (4) intraoperative IV cephalexin (1 g) and postoperative oral azithromycin (1.5 g).

RESULTS

A significantly higher rate of infection occurred in patients receiving combination intraoperative and/or postoperative antibiotic prophylaxis. The most frequently cultured organisms included Enterobacter and Pseudomonas species.

CONCLUSION

The rate of postoperative bacterial infections after full-face CO2 laser resurfacing in this retrospective study was not significantly reduced with the use of prophylactic antibiotics.

Synthesis and Insect Growth Regulatory Activity of Alkoxy-Substituted Benzaldoxime Ethers

Alkoxy-substituted benzaldoxime ethers, namely (i) 3-methoxy-4-ethoxybenzaldoxime N-O-alkyl ethers, (ii) 3,4-dimethoxybenzaldoxime N-O-alkyl ethers, and (iii) 3,4-methylenedioxybenzaldoxime N-O-alkyl ethers, have been synthesized and evaluated for their insect growth regulatory activity against fifth-instar nymphs of the desert locust Schistocerca gregaria F. When injected into insect hemolymph at the lowest dose level of 3 µg/nymph, 3,4-methylenedioxybenzaldoxime N-O-methyl ether and 3,4-methylenedioxybenzaldoxime N-O-isopropyl ether showed 40 and 50% growth deformities respectively. On topical application (at 20 µg/nymph) 3-methoxy-4-ethoxybenzaldoxime N-O-methyl ether inflicted 100% abnormalties in insect growth. Structure-activity relationship studies revealed that maximum activity was associated with compounds having three carbons in the oxime ether moiety.

Characterization by arbitrary primer polymerase chain reaction of polychlorinated biphenyl (PCB)-degrading strains of Comamonas testosteroni isolated from PCB-contaminated soil

In this study, we isolated and characterized biphenyl (BP) and polychlorinated biphenyl (PCB) degrading bacterial strains found in PCB-contaminated soil from an auto manufacturing plant located in Syracuse, New York. Twenty-one BP and PCB-degrading bacteria were randomly selected to form a representative sample of the bacterial population present at the site. Of the 21 bacteria, 13 were identified as Comamonas testosteroni, constituting about 60% of the bacterial population examined. Other PCB degraders identified were Acidovorax facilis, Alcaligenes xylosoxydans, Bacillus sphericus, Hydrogenophaga pseudoflava, Pseudomonas avanae, and Rhodococcus fascians. Owing to the abundance of C. testosteroni at this site, only these isolates were further characterized for their PCB congener degradation profile, 2,3-dihydroxybiphenyl 1,2-dioxygenase activity, and genetic relatedness by polymerase chain reaction (PCR) analysis. The PCB congener degradation pattern revealed a high degree of variability among the C. testosteroni isolates. The majority of the C. testosteroni isolates tested could degrade more than 95% of the PCB congeners up to pentachlorinated biphenyl. Only four isolates could degrade more than 80% of hexachlorobiphenyl. All 12 isolates of C. testosteroni tested were able to attack 2,3,4,5,6,3',4'-heptachlorobiphenyl, indicating involvement of biphenyl 2,3-dioxygenase, while 2,3,5,6,2',3',6'-heptachlorobiphenyl was attacked by 6 strains, suggesting an oxidation reaction mediated by 3,4-dioxygenase. 2,3-Dihydroxybiphenyl 1,2-dioxygenase activity was also found to vary among the C. testosteroni isolates tested in this study. Eleven strains showed 2,3-dihydroxybiphenyl 1,2-dioxygenase activity specific for 2,3-dihydroxybiphenyl, whereas isolate BW 169 could metabolize both 2,3-dihydroxybiphenyl and 4-methylcatechol, and isolate BW74 had the ability to metabolize all three substrates (2,3-dihydroxybiphenyl, 4-chlorocatechol, and 4-methylcatechol).(ABSTRACT TRUNCATED AT 250 WORDS)

Genotoxicity of polychlorinated biphenyls (PCBs): recombinogenesis by biotransformation products

A coplanar polychlorinated biphenyl (PCB) when eaten by test animals increased the rate of recombination in somatic cells, indicating a new mechanism of action for these compounds. Using the eye-mosaic test a high bioactivation strain of Drosophila that consumed 4,4'-dichlorobiphenyl (4,4'-DCB) manifested a genotoxicity rate that was three-fold greater than that in animals fed the solvent-spiked medium. This compound was not genotoxic in a suppressed bioactivation strain indicating that genotoxicity requires bioactivation of the compound. High bioactivation test strains made heterozygous for a paracentric inversion, a chromosomal rearrangement that suppresses homologous recombination, exhibited significantly reduced genotoxicity after treatment.

Simultaneous Liquid Chromatographic Determination of Fenamiphos and Its Metabolites in Soil

A reversed-phase liquid chromatographic method has been developed for the determination of fenamiphos and the metabolites fenamiphos sulfoxide, fenamiphos sulfone, 3-methyl-4-(methylthlo)- phenol, and 3-methyl-4-(methylsulflnyl)phenol. Trace quantities of the nematlclde and Its metabolites In soil can be determined simultaneously. The limit of detection of the method was 5 ppm. Recoveries of fenamiphos and Its degradation products at fortification levels of 25,50, and 100 ppm ranged from 99.2 to 100.8%. Standard deviations ranged from 0.29 to 0.70 ppm.

Construction and applications of DNA probes for detection of polychlorinated biphenyl-degrading genotypes in toxic organic-contaminated soil environments

Several DNA probes for polychlorinated biphenyl (PCB)-degrading genotypes were constructed from PCB-degrading bacteria. These laboratory-engineered DNA probes were used for the detection, enumeration, and isolation of specific bacteria degrading PCBs. Dot blot analysis of purified DNA from toxic organic chemical-contaminated soil bacterial communities showed positive DNA-DNA hybridization with a 32P-labeled DNA probe (pAW6194, cbpABCD). Less than 1% of bacterial colonies isolated from garden topsoil and greater than 80% of bacteria isolated from PCB-contaminated soils showed DNA homologies with 32P-labeled DNA probes. Some of the PCB-degrading bacterial isolates detected by the DNA probe method did not show biphenyl clearance. The DNA probe method was found to detect additional organisms with greater genetic potential to degrade PCBs than the biphenyl clearance method did. Results from this study demonstrate the usefulness of DNA probes in detecting specific PCB-degrading bacteria, abundance of PCB-degrading genotypes, and genotypic diversity among PCB-degrading bacteria in toxic chemical-polluted soil environments. We suggest that the DNA probe should be used with caution for accurate assessment of PCB-degradative capacity within soils and further recommend that a combination of DNA probe and biodegradation assay be used to determine the abundance of PCB-degrading bacteria in the soil bacterial community.

Cloning of bacterial genes specifying degradation of 4-chlorobiphenyl from Pseudomonas putida OU83

Genes capable of 4-chlorobiphenyl (4-CBP) degradation were cloned from 4-CBP-degrading Pseudomonas putida OU83 by using a genomic library which was constructed in the broad-host-range cosmid vector pCP13. P. putida AC812 containing chimeric cosmid-expressing enzymes involved in the 4-CBP degradation pathway were identified by detecting 3-phenylcatechol dioxygenase activity (3-PDA). Chimeric cosmid clones pOH83, pOH84, pOH85, pOH87, and pOH88 positive for 3-PDA grew in synthetic basal medium containing 4-CBP (5 mM) as a carbon source. Restriction digestion analysis of recombinant cosmids showed DNA inserts ranging from 6 to 30 kilobase pairs. Southern hybridization data revealed that the cloned DNA inserts originated from strain OU83. Gas chromatography-mass spectrometry analysis of the metabolites of P. putida AC812(pOH88) incubated with 4-CBP and 4'-chloro-3-phenylcatechol showed the formation of 4-chlorobenzoic acid and benzoic acid. These results demonstrate that the cloned DNA fragments contain genes encoding for chlorobiphenyl dioxygenase (cbpA), dihydrodiol dehydrogenase (cbpB), 4'-chloro-3-phenylcatechol dioxygenase (cbpC), a meta-cleavage compound (a chloro derivative of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate) hydrolase (cbpD), and a new dechlorinating activity (dcpE). The location of the cbpC gene specifying 3-PDA was determined by subcloning an EcoRI DNA fragment (9.8 kilobase pairs) of pOH88 in plasmid vector pUC19. The cloned gene encoding 3-PDA was expressed in Escherichia coli HB101 and had substrate specificity only for 3-phenylcatechol and 4'-chloro-3-phenylcatechol.

Molecular cloning of 3-phenylcatechol dioxygenase involved in the catabolic pathway of chlorinated biphenyl from Pseudomonas putida and its expression in Escherichia coli

Genes encoding 3-phenylcatechol dioxygenases were cloned from the chlorobiphenyl-degrading Pseudomonas putida strain OU83, using broad-host-range cosmid vector pCP13. Restriction enzyme analysis of DNA from 2,3-dioxygenase-positive chimeric cosmids showed DNA inserts ranging in size from 6.0 to 30 kilobases. The origin of the DNA insert in hybrid clones was established by using 32P-labeled hybrid clones (pOH101 and pOH810). A 2.3-kilobase HindIII fragment was common to two clones. The 2,3-dioxygenase from the parent P. putida strain, OU83, and the recombinant clones (pOH101 and pOH8101) showed similar characteristics as determined by isoelectric focusing and polyacrylamide gel electrophoresis. The 2,3-dioxygenase from the Escherichia coli recombinant cosmid showed a pI of 5.0, a Km of 14 microM, and broad substrate activity with catechol, 4-chlorocatechol, 4-methylcatechol, and 2,3-dihydroxybiphenyl.

Protein patterns, serotyping and plasmid DNA profiles in the epidemiologic fingerprinting of Pseudomonas aeruginosa

The epidemiological typing schemes based on serotyping, antibiotic susceptibility pattern, plasmid DNA profile, and protein patterns determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were evaluated for their usefulness in typing clinical isolates of Pseudomonas aeruginosa. The serotypability was lower (45%) than reported in the literature (85-95%). The most commonly found serotypes were O:1 (19%), O:11 (25%), O:6 (35%). The electrophoretic analysis of plasmid DNAs showed plasmids (molecular weight = 1 to greater than 40 megadaltons). Two plasmids of Mr 2 and 38 megadaltons were found in various serotypes. The restriction enzyme analysis of plasmid DNA showed identical DNA fragment patterns among distinct serotypes. The SDS-PAGE protein banding patterns of whole-cell proteins showed homogeneity among the strains. However, analysis of the soluble protein patterns of the strains showed sufficiently distinct protein profiles that can be used to differentiate between various strains. The results of this study demonstrate that the electrophoretic patterns of soluble proteins, in combination with plasmid DNA profile or serotyping, can be of value in the epidemiologic fingerprinting of clinical isolates of Pseudomonas aeruginosa.

Plasmid profiles and klebocin types in epidemiologic studies of infections by Klebsiella pneumoniae

The epidemiological methods of klebocin typing, antibiogram and plasmid DNA profile were evaluated using organisms isolated from a suspected epidemic of gentamicin-resistant Klebsiella pneumoniae and unrelated strains from different geographical areas as controls. The electrophoretic analysis of plasmid DNAs from Klebsiella pneumoniae showed the presence of at least one and up to as many as seven plasmids in each strain. The molecular weight of plasmid DNAs ranged from 1 to greater than 70 mega daltons. While none of the control Klebsiella pneumoniae strains showed identical plasmid profiles, 63% of the epidemic-related Klebsiella pneumoniae strains did. Klebocin typing and plasmid DNA profile gave different results for the same strains. Plasmid DNA profile was found to be a more valuable method than klebocin typing alone or klebocin typing in combination with antibiogram for differentiating epidemiologically related from unrelated isolates. Both plasmid DNA profile and klebocin typing methods were superior to antibiogram.

Bacteriophage T5 growth in Escherichia coli containing PstI fragments of the colicin Ib plasmid

PstI restriction fragments of the colicin Ib (ColIb) plasmid have been cloned into the Apr gene of the pBR322 vector. Colicin-producing clones (Col+) all contained two common PstI (L and U) fragments, 2000 and 800 bp long, respectively. All of these colicin producers were found to permit the normal growth of bacteriophage T5; the presence of the whole ColIb plasmid causes an abortive T5 or BF23 phage infection. None of the other clones selected for their inability to propagate T5 produced colicin. The clones (Abi+) that permitted only an abortive infection by T5 contained a single restriction fragment, O (1600 bp), which was not found in any of the colicin producers. Likewise, the specific fragments (L and U) found in the Col+ clones were not found in the Abi+ clones. These data are very hard to reconcile with the hypothesis of a colicin-induced cell deterioration after T5 phage infection.