Using Participatory Mapping to Diagnose Upstream Determinants of Health and Prescribe Downstream Policy-Based Interventions.

Participatory mapping is a powerful methodology for working with community residents to examine social and environmental determinants of public health disparities. However, this empowering methodology has only been applied sparingly in public health research and practice, with limited examples in the literature. To address this literature gap, we 1) review participatory mapping approaches that may be applied to exploring place-based factors that affect community health, and 2) present a mixed-methods participatory geographic information systems (PGIS) examination of neighborhood assets (eg, streetlights) and challenges (eg, spaces of crime and violence) related to access to public parks in South Los Angeles, California. By taking a participatory, fine-grained spatial approach to examining public park access with input from 40 South Los Angeles adolescent and adult residents, our community-engaged PGIS approach identified tobacco shops as previously unrecognized community institutions that are associated with increased neighborhood crime and violence. Our investigation revealed unique challenges in community-level public park access that would likely have been overlooked by conventional spatial epidemiology and social science methods, such as surveys and questionnaires. Furthermore, our granular community-informed approach supported resident and stakeholder advocacy efforts toward reducing the proliferation of tobacco shops through community organizing and policy change initiatives. We thus contend that it would benefit public health research and practice to further integrate empowering, grassroots-based participatory mapping approaches toward informing advocacy efforts and policies that promote health and well-being in disadvantaged communities.

Hydroxyatrazine N-ethylaminohydrolase (AtzB): an amidohydrolase superfamily enzyme catalyzing deamination and dechlorination.

Hydroxyatrazine [2-(N-ethylamino)-4-hydroxy-6-(N-isopropylamino)-1,3,5-triazine] N-ethylaminohydrolase (AtzB) is the sole enzyme known to catalyze the hydrolytic conversion of hydroxyatrazine to N-isopropylammelide. AtzB, therefore, serves as the point of intersection of multiple s-triazine biodegradative pathways and is completely essential for microbial growth on s-triazine herbicides. Here, atzB was cloned from Pseudomonas sp. strain ADP and its product was purified to homogeneity and characterized. AtzB was found to be dimeric, with subunit and holoenzyme molecular masses of 52 kDa and 105 kDa, respectively. The k(cat) and K(m) of AtzB with hydroxyatrazine as a substrate were 3 s(-1) and 20 microM, respectively. Purified AtzB had a 1:1 zinc-to-subunit stoichiometry. Sequence analysis revealed that AtzB contained the conserved mononuclear amidohydrolase superfamily active-site residues His74, His76, His245, Glu248, His280, and Asp331. An intensive in vitro investigation into the substrate specificity of AtzB revealed that 20 of the 51 compounds tested were substrates for AtzB; this allowed for the identification of specific substrate structural features required for catalysis. Substrates required a monohydroxylated s-triazine ring with a minimum of one primary or secondary amine substituent and either a chloride or amine leaving group. AtzB catalyzed both deamination and dechlorination reactions with rates within a range of one order of magnitude. This differs from AtzA and TrzN, which do not catalyze deamination reactions, and AtzC, which is not known to catalyze dechlorination reactions.

Metabolism of thioamides by Ralstonia pickettii TA.

Information on bacterial thioamide metabolism has focused on transformation of the antituberculosis drug ethionamide and related compounds by Mycobacterium tuberculosis. To study this metabolism more generally, a bacterium that grew using thioacetamide as the sole nitrogen source was isolated via enrichment culture. The bacterium was identified as Ralstonia pickettii and designated strain TA. Cells grown on thioacetamide also transformed other thioamide compounds. Transformation of the thioamides tested was dependent on oxygen. During thioamide degradation, sulfur was detected in the medium at the oxidation level of sulfite, further suggesting an oxygenase mechanism. R. pickettii TA did not grow on thiobenzamide as a nitrogen source, but resting cells converted thiobenzamide to benzamide, with thiobenzamide S-oxide and benzonitrile detected as intermediates. Thioacetamide S-oxide was detected as an intermediate during thioacetamide degradation, but the only accumulating metabolite of thioacetamide was identified as 3,5-dimethyl-1,2,4-thiadiazole, a compound shown to derive from spontaneous reaction of thioacetamide and oxygenated thioacetamide species. This dead-end metabolite accounted for only ca. 12% of the metabolized thioacetamide. Neither acetonitrile nor acetamide was detected during thioacetamide degradation, but R. pickettii grew on both compounds as nitrogen and carbon sources. It is proposed that R. pickettii TA degrades thioamides via a mechanism involving consecutive oxygenations of the thioamide sulfur atom.

Substrate specificity and colorimetric assay for recombinant TrzN derived from Arthrobacter aurescens TC1.

The TrzN protein, which is involved in s-triazine herbicide catabolism by Arthrobacter aurescens TC1, was cloned and expressed in Escherichia coli as a His-tagged protein. The recombinant protein was purified via nickel column chromatography. The purified TrzN protein was tested with 31 s-triazine and pyrimidine ring compounds; 22 of the tested compounds were substrates. TrzN showed high activity with sulfur-substituted s-triazines and the highest activity with ametryn sulfoxide. Hydrolysis of ametryn sulfoxide by TrzN, both in vitro and in vivo, yielded a product(s) that reacted with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl) to generate a diagnostic blue product. Atrazine chlorohydrolase, AtzA, did not hydrolyze ametryn sulfoxide, and no color was formed by amending those enzyme incubations with NBD-Cl. TrzN and AtzA could also be distinguished by reaction with ametryn. TrzN, but not AtzA, hydrolyzed ametryn to methylmercaptan. Methylmercaptan reacted with NBD-Cl to produce a diagnostic yellow product having an absorption maximum at 420 nm. The yellow color with ametryn was shown to selectively demonstrate the presence of TrzN, but not AtzA or other enzymes, in whole microbial cells. The present study was the first to purify an active TrzN protein in recombinant form and develop a colorimetric test for determining TrzN activity, and it significantly extends the known substrate range for TrzN.

Mechanical prosthetic valve-associated strands: Pathologic correlates to transesophageal echocardiography.

Echocardiographic detection of prosthetic valve-associated strands has previously been reported, but their clinical relevance is unclear. Limited data are available regarding the cause, composition, and natural history of these strands. This report presents the gross and histopathologic findings of an explanted mechanical prosthetic valve shown by transesophageal echocardiography to have several strands. The patient had not experienced prior neurologic symptoms. Potential causes of strand formation in various clinical settings are also discussed.

Arthrobacter aurescens TC1 metabolizes diverse s-triazine ring compounds.

Arthrobacter aurescens strain TC1 was isolated without enrichment by plating atrazine-contaminated soil directly onto atrazine-clearing plates. A. aurescens TC1 grew in liquid medium with atrazine as the sole source of nitrogen, carbon, and energy, consuming up to 3,000 mg of atrazine per liter. A. aurescens TC1 is metabolically diverse and grew on a wider range of s-triazine compounds than any bacterium previously characterized. The 23 s-triazine substrates serving as the sole nitrogen source included the herbicides ametryn, atratone, cyanazine, prometryn, and simazine. Moreover, atrazine substrate analogs containing fluorine, mercaptan, and cyano groups in place of the chlorine substituent were also growth substrates. Analogs containing hydrogen, azido, and amino functionalities in place of chlorine were not growth substrates. A. aurescens TC1 also metabolized compounds containing chlorine plus N-ethyl, N-propyl, N-butyl, N-s-butyl, N-isobutyl, or N-t-butyl substituents on the s-triazine ring. Atrazine was metabolized to alkylamines and cyanuric acid, the latter accumulating stoichiometrically. Ethylamine and isopropylamine each served as the source of carbon and nitrogen for growth. PCR experiments identified genes with high sequence identity to atzB and atzC, but not to atzA, from Pseudomonas sp. strain ADP.

Purification, substrate range, and metal center of AtzC: the N-isopropylammelide aminohydrolase involved in bacterial atrazine metabolism.

N-Isopropylammelide isopropylaminohydrolase, AtzC, the third enzyme in the atrazine degradation pathway in Pseudomonas sp. strain ADP, catalyzes the stoichiometric hydrolysis of N-isopropylammelide to cyanuric acid and isopropylamine. The atzC gene was cloned downstream of the tac promoter and expressed in Escherichia coli, where the expressed enzyme comprised 36% of the soluble protein. AtzC was purified to homogeneity by ammonium sulfate precipitation and phenyl column chromatography. It has a subunit size of 44,938 kDa and a holoenzyme molecular weight of 174,000. The K(m) and k(cat) values for AtzC with N-isopropylammelide were 406 micro M and 13.3 s(-1), respectively. AtzC hydrolyzed other N-substituted amino dihydroxy-s-triazines, and those with linear N-alkyl groups had higher k(cat) values than those with branched alkyl groups. Native AtzC contained 0.50 eq of Zn per subunit. The activity of metal-depleted AtzC was restored with Zn(II), Fe(II), Mn(II), Co(II), and Ni(II) salts. Cobalt-substituted AtzC had a visible absorbance band at 540 nm (Delta epsilon = 84 M(-1) cm(-1)) and exhibited an axial electron paramagnetic resonance (EPR) signal with the following effective values: g((x)) = 5.18, g((y)) = 3.93, and g((z)) = 2.24. Incubating cobalt-AtzC with the competitive inhibitor 5-azacytosine altered the effective EPR signal values to g((x)) = 5.11, g((y)) = 4.02, and g((z)) = 2.25 and increased the microwave power at half saturation at 10 K from 31 to 103 mW. Under the growth conditions examined, our data suggest that AtzC has a catalytically essential, five-coordinate Zn(II) metal center in the active site and specifically catalyzes the hydrolysis of intermediates generated during the metabolism of s-triazine herbicides.

Enzymatic degradation of chlorodiamino-s-triazine.

2-Chloro-4,6-diamino-s-triazine (CAAT) is a metabolite of atrazine biodegradation in soils. Atrazine chlorohydrolase (AtzA) catalyzes the dechlorination of atrazine but is unreactive with CAAT. In this study, melamine deaminase (TriA), which is 98% identical to AtzA, catalyzed deamination of CAAT to produce 2-chloro-4-amino-6-hydroxy-s-triazine (CAOT). CAOT underwent dechlorination via hydroxyatrazine ethylaminohydrolase (AtzB) to yield ammelide. This represents a newly discovered dechlorination reaction for AtzB. Ammelide was subsequently hydrolyzed by N-isopropylammelide isopropylaminohydrolase to produce cyanuric acid, a compound metabolized by a variety of soil bacteria.

Description and evaluation of a glycemic management protocol for patients with diabetes undergoing heart surgery.

OBJECTIVE: To evaluate a protocol for glycemic management in the treatment of postoperative heart patients with diabetes in the setting of a community hospital. METHODS: The protocol included a standardized guideline in tabular form for nurse-implemented insulin infusion ("drip") therapy for postoperative glycemic control. At the time of discontinuation of the insulin drip, the glycemic status of patients with diabetes was managed by the endocrine department. Overall, 29 patients were assessed without and 29 patients with use of the protocol in a community hospital. RESULTS: From postoperative days 0 through 4, use of the protocol resulted in a greater number of blood glucose determinations, a trend toward greater utilization of insulin drip therapy without a significant increase in the number of patients treated with insulin drip, and no change in the frequency of hypoglycemic episodes. During the same time interval, the percentages of postoperative days during which at least one blood glucose value equaled or exceeded 250 mg/dL were 27.5% without the protocol and 16.8% with use of the protocol (P = 0.0318). The principal finding of the study was reduction in the percentage of postoperative days during which mean blood glucose values equaled or exceeded 200 mg/dL to less than half the previously observed frequency-from 38.4% without the protocol to 16.8% with the protocol (P = 0.0001). The effectiveness of the insulin drip component of the protocol is suggested by a trend, shown on postoperative days 2 through 4, of 70 patient days with mean blood glucose levels <200 mg/dL (58 of these days without insulin drip therapy) and 15 patient days with mean blood glucose values > or =200 mg/dL (none of these days associated with same-day insulin drip therapy). CONCLUSION: A standardized approach to insulin drip therapy, in combination with subspecialty consultation for follow-up glycemic management with use of subcutaneous administration of insulin, can improve glycemic control in postoperative heart patients without continuation of insulin drip therapy outside the critical-care unit. The trends observed on postoperative days 2 through 4, that most patients maintained glycemic control without insulin drip therapy and that all failures of glycemic control occurred among patients who no longer received insulin drip therapy, suggest the possibility of developing criteria for selection of patients for continuation of insulin infusion outside the critical-care unit.

NextStitch: double-stranded suture chain, a tool to optimize approximation of sutures in valve surgery with echocardiographic correlation.

Suture technique for valve replacement surgery has often focused on decreasing the soft tissue injury that leads to pseudoaneurysm formation and associated latent infection. There is universal recognition that precise suture placement is essential for avoiding adverse sequelae while allowing flexibility during the implantation of the prosthesis. The use of a continuous chain of linked horizontal mattress sutures (NextStitch) has allowed maximal precision in the approximation of sutures within the valve annulus. The product was used in a series of consecutive mitral and aortic valve replacements, and typical echocardiographic images from each type of implantation are presented. Postoperative echocardiography images revealed that no perivalvular leaks occurred and that NextStitch did not obscure detailed interrogation or assessment of the valve prosthesis.

Incidence of False-Positive Results for Assays Used To Detect Antibiotics in Milk.

The incidence of false-positive results from milk assays for antimicrobial agents was determined for composite milk samples collected from 407 lactating dairy cows with a history of no antibiotic treatment for a minimum of 30 days. Milk samples were also cultured for bacteria and analyzed for somatic cell count. Mean herd prevalence of intramammary infections (±SEM) caused by Streptococcus agalactiae and Staphylococcus aureus was 3.3 ± 2.8 and 20.2 ± 9.5% of lactating cows, respectively. All 407 milk samples were assayed for antibiotics with three commercial tests; a fourth test was used to assay 391 samples. Samples were assayed twice with each test, and if the results from these repetitions did not agree, a third assay was performed and the result obtained in two of the three repetitions was reported. Because samples were only collected from cows with no antimicrobial treatment for a minimum of 30 days, positive assays were considered to be false-positive results. Three test kits did not yield any false-positive results, one test kit had 5 false-positive results of 407 samples collected (specificity, 98.8%). Although there was a trend for false-positive samples to have a higher somatic cell count than negative samples, the low incidence of false-positive results did not allow a meaningful comparison. We conclude that the incidence of false-positive results is very low when testing milk from cows that have a history of no clinical mastitis or antimicrobial treatment.