Distribution and stability of sulfate-reducing prokaryotic and hydrogenotrophic methanogenic assemblages in nutrient-impacted regions of the Florida Everglades

Although the influence of phosphorus loading on the Everglades ecosystem has received a great deal of attention, most research has targeted macro indicators, such as those based on vegetation or fauna, or chemical and physical parameters involved in biogeochemical cycles. Fewer studies have addressed the role of microorganisms, and these have mainly targeted gross informative parameters such as microbial biomass, enzymatic activities, and microbial enumerations. The objectives of this study were to characterize the dynamics of sulfate-reducing and methanogenic assemblages using terminal restriction fragment length polymorphism (T-RFLP) targeting the dissimilatory sulfite reductase (dsrA) and methyl coenzyme M reductase (mcrA) genes, respectively, and assess the impact of nutrient enrichment on microbial assemblages in the northern Everglades. T-RFLP combined with principal component analysis was a powerful technique to discriminate between soils from sites with eutrophic, transitional, and oligotrophic nutrient concentrations. dsrA T-RFLP provided a higher level of discrimination between the three sites. mcrA was a relatively weaker system to distinguish between sites, since it could not categorically discriminate between eutrophic and transition soil samples, but may be useful as an early indicator of phosphorus loading which is altering hydrogenotrophic methanogenic community in the transition zones, making them more similar to eutrophic zones. Clearly, targeting a combination of different microbial communities provides greater insight into the functioning of this ecosystem and provides useful information for understanding the relationship between eutrophication effects and microbial assemblages.

Thyrotropin receptor/thyroglobulin messenger ribonucleic acid in peripheral blood and fine-needle aspiration cytology: diagnostic synergy for detecting thyroid cancer

RT-PCR for thyroglobulin (Tg) and TSH receptor (TSHR) mRNA has been used to detect circulating thyroid cancer cells. Little is known, however, regarding the preoperative sensitivity of this test to detect cancer. Seventy-two patients with thyroid disease (36 with malignancy and 36 with benign disease) were evaluated preoperatively. TSHR and Tg mRNA transcripts were detected by RT-PCR assays, previously determined to be specific for cancer cells. There was 100% concordance between TSHR and Tg mRNA RT-PCR results. Of 36 cancer patients, 11 had recurrent disease, and all were positive by RT-PCR. Among 25 patients with no prior thyroid surgery, 18 tested positive preoperatively (sensitivity 72%). Seven of 36 patients with benign disease tested positive (specificity 80%). The overall preoperative diagnostic accuracy was 77%. Preoperative fine-needle aspiration (FNA) biopsy was performed on 46 of 61 patients with no prior thyroid surgery. FNA was diagnostic in 28 (61%) patients. Preoperative cytology was adequate but not diagnostic in 18 (39%) patients. RT-PCR correctly classified 14 of these 18 patients with indeterminate FNA, and the test detected three of four cancer patients as positive (75% sensitive) and 11 of 14 patients (78% specific) with benign disease as negative. The combined diagnostic performance characteristics for RT-PCR and FNA cytology were sensitivity = 95%, specificity = 83%, and diagnostic accuracy = 89%, with positive and negative predictive values of 84 and 95%, respectively. Our results suggest that the molecular detection of circulating thyroid cancer cells by RT-PCR for TSHR/Tg mRNA complements FNA cytology in the preoperative differentiation of benign from malignant thyroid disease and their combined use may save unnecessary surgeries.

Laparoscopic bowel injury in an animal model: monocyte migration and apoptosis

BACKGROUND

Unrecognized laparoscopic bowel injury has a delayed and covert presentation. Differences in monocyte migration and apoptosis between laparoscopic and open bowel injury were determined.

METHODS

For this study, 24 rabbits were divided into laparoscopic (n = 9) and open surgical (n = 9) bowel injury groups and a control group (n = 6) without bowel injury. Bowel injury was created using monopolar electrocautery. The animals were killed 1 day, 1 week, and 2 weeks after surgery. Monocyte migration assay was performed across a modified Boyden chamber. Apoptosis was assessed by DNA fluorescent stain H-33342.

RESULTS

In laparoscopy, monocyte apoptosis was decreased (p < 0.001), and migration was increased (p < 0.05), as compared with the open group. Apoptosis increased over time in both study groups, and was higher than in the control group (p < 0.001). Migration was decreased in both study groups as compared with the control group (p < 0.05)

CONCLUSIONS

These results suggest decreased immune system priming with laparoscopic bowel injury, which may contribute to the masking of relevant signs and symptoms of peritonitis.

Optimization of low-cost phosphorus removal from wastewater using co-treatments with constructed wetlands

Eighteen wastewater treatment systems were operated for one year to investigate phosphorus (P) removal. Systems paired co-treatment reactors containing iron or calcium drinking water treatment residuals with vertical-flow constructed wetland mesocosms planted with Schoenoplectus tabernaemontani (K.C. Gmel.) Palla. For secondary municipal wastewater, soluble reactive P (SRP) concentrations were reduced from 0.70 to 0.03 mg L(-1) (95%) or 0.01 mg L(-1) (98%) by systems with the calcium or iron co-treatments, respectively (compared to 0.09 mg L(-1) or 87% by controls). Total P (TP) concentrations were reduced from 1.00 to 0.07 mg L(-1) (93%) and 0.05 mg L(-1) (95%) by the same treatments (compared to 0.16 mg L(-1) or 84% by controls). For anaerobically digested dairy wastewater, SRP was reduced from 7.68 to 6.43 mg L(-1) (16%) or 5.95 mg L(-1) (22%) by the systems with calcium or iron, respectively (compared to 7.37 mg L(-1) or 4% by controls). For this wastewater, the TP was reduced from 48.5 to 22.5 mg L(-1) (53%) and 22.7 mg L(-1) (53%) by the same treatments (compared to 24.1 mg L(-1) or 50% by controls) but performance improved substantially with a design modification tested.

Response of biogeochemical indicators to a drawdown and subsequent reflood

Temporal oscillations in hydrology are a common occurrence in wetlands and can result in alternating flooded and drained conditions in the surface soil. These oscillations in water levels can stimulate microbial activities and result in the mobilization and redistribution of significant amounts of carbon (C), nitrogen (N), and phosphorus (P). The goal of this study was to experimentally simulate a drawdown and reflood of marsh soil from a nutrient-enriched site and a reference site of a wetland (Blue Cypress Marsh Conservation Area, Florida). The goal was to better understand the changes in biogeochemistry and microbial activities present in these soils as a result of hydrological fluctuations. Measurements of dissolved reactive phosphorus (DRP), ammonia, and nitrate in the floodwater indicated significantly higher (alpha = 0.05) NH(4)(+) and DRP fluxes from the nutrient-enriched site; floodwaters in the cores from both sites contained significant NO(3)(-) concentrations (9.6 mg N L(-1)), which was rapidly consumed over the core incubation period (30 d). Water level drawdown and reflooding initially stimulated the soil microbial biomass, methanogenic rates, and extracellular enzyme activities (acid phosphatase and beta-glucosidase). The anaerobic microbial metabolic activities (CO(2)) where initially significantly (alpha = 0.05) enhanced by the reflood, resulting in roughly equivalent rates as the aerobic respiratory activities (CO(2)), presumably as a function of the high water column NO(3)(-) levels. This study illustrates that the reflood event in the hydrological cycles in a wetland can significantly stimulate the activities of hydrolytic enzymes and microbiological communities in these soils.

Phylogenetic characterization of methanogenic assemblages in eutrophic and oligotrophic areas of the Florida Everglades

Agricultural activities have produced well-documented changes in the Florida Everglades, including establishment of a gradient in phosphorus concentrations in Water Conservation Area 2A (WCA-2A) of the northern Everglades. An effect of increased phosphorus concentrations is increased methanogenesis in the eutrophic regions compared to the oligotrophic regions of WCA-2A. The goal of this study was to identify relationships between eutrophication and composition and activity of methanogenic assemblages in WCA-2A soils. Distributions of two genes associated with methanogens were characterized in soils taken from WCA-2A: the archaeal 16S rRNA gene and the methyl coenzyme M reductase gene. The richness of methanogen phylotypes was greater in eutrophic than in oligotrophic sites, and sequences related to previously cultivated and uncultivated methanogens were found. A preferential selection for the order Methanomicrobiales was observed in mcrA clone libraries, suggesting primer bias for this group. A greater diversity within the Methanomicrobiales was observed in mcrA clone libraries than in 16S rRNA gene libraries. 16S rRNA phylogenetic analyses revealed a dominance of clones related to Methanosaeta spp., an acetoclastic methanogen dominant in environments with low acetate concentrations. A significant number of clones were related to Methanomicrobiales, an order characterized by species utilizing hydrogen and formate as methanogenic substrates. No representatives of the orders Methanobacteriales and Methanococcales were found in any 16S rRNA clone library, although some Methanobacteriales were found in mcrA libraries. Hydrogenotrophs are the dominant methanogens in WCA-2A, and acetoclastic methanogen genotypes that proliferate in low acetate concentrations outnumber those that typically dominate in higher acetate concentrations.

Cefepime versus ceftazidime for treatment of pneumonia

Consecutive patients with pneumonia, treated with cefepime (n = 66) or ceftazidime (n = 132), were evaluated in a retrospective, observational study. There was no significant difference between the two treatment groups with respect to age, underlying diseases, acute physical and chronic health evaluation score, intensive care unit admission, presence of sepsis, community or hospital acquisition, causative organism, duration of therapy, death, cure or improvement in infection, adverse events, superinfections, presence of vancomycin-resistant enterococcus (VRE) and resistance to therapy. Post-therapy hospitalization (days) and vancomycin co-administration were significantly lower, and time to vancomycin initiation significantly higher, in the cefepime compared with the ceftazidime group. The results suggest a trend towards less resistance on therapy, less VRE, reduced vancomycin use and shorter post-therapy hospitalization in patients treated with cefepime compared with ceftazidime. The clinical outcomes for hospitalized patients treated for serious pneumonia were similar between the two groups.

Syntrophic-methanogenic associations along a nutrient gradient in the Florida Everglades

Nutrient runoff from the Everglades Agricultural Area resulted in a well-documented gradient of phosphorus concentrations in soil and water, with concomitant ecosystem-level changes, in the northern Florida Everglades. It was recently reported that sulfate-reducing prokaryote assemblage composition, numbers, and activities are dependent on position along the gradient (H. Castro, K. R. Reddy, and A. Ogram, Appl. Environ. Microbiol. 68:6129-6137, 2002). The present study utilized a combination of culture- and non-culture-based approaches to study differences in composition of assemblages of syntrophic and methanogenic microbial communities in eutrophic, transition, and oligotrophic areas along the phosphorus gradient. Methanogenesis rates were much higher in eutrophic and transition regions, and sequence analysis of 16S rRNA gene clone libraries constructed from samples taken from these regions revealed differences in composition and activities of syntroph-methanogen consortia. Methanogens from eutrophic and transition regions were almost exclusively composed of hydrogenotrophic methanogens, with approximately 10,000-fold-greater most probable numbers of hydrogenotrophs than of acetotrophs. Most cultivable strains from eutrophic and transition regions clustered within novel lineages. In non-culture-based studies to enrich syntrophs, most bacterial and archaeal clones were either members of novel lineages or closely related to uncultivated environmental clones. Novel cultivable Methanosaeta sp. and fatty acid-oxidizing bacteria related to the genera Syntrophomonas and Syntrophobacter were observed in microcosms containing soil from eutrophic regions, and different lines of evidence indicated the existence of novel syntrophic association in eutrophic regions.

Review article: the evolving role of liver biopsy

Liver biopsy is traditionally the 'gold standard' for the evaluation of liver diseases. There are several situations in which its role is being challenged. In hepatitis C, liver biopsy helps assess prognosis and treatment candidacy. An important exception is genotype 2 or 3 because treatment is more likely to succeed and therapy is relatively short in duration. For hepatitis B, liver biopsy gives some prognostic information, but serologic tests and hepatic biochemical tests are the primary determinants of treatment candidacy. Non-alcoholic fatty liver disease can be accurately diagnosed without a liver biopsy and, furthermore, there are no specific therapies available. The role of liver biopsy to assess methotrexate-associated hepatotoxicity remains controversial. Finally, patients with focal liver lesions usually do not require biopsy and, in the case of hepatocellular carcinoma, biopsy carries a risk of needle-track seeding. In short, the need for liver biopsy depends on the specific situation and should be performed when there is sufficient uncertainty about diagnosis, severity of disease, prognosis, and treatment decisions.

A free-standing low-risk maternity unit in the United Kingdom: does it have a role?

This study aimed to evaluate the safety of this birth setting for low-risk deliveries based on our hospital protocol. The study was carried out at Heatherwood Hospital, Ascot (a low-risk unit) and Wexham Park Hospital, Slough, Berkshire (a consultant-led unit). This was a retrospective analysis of the computerised records and statistics of low-risk women delivered at Heatherwood Hospital, Ascot, UK following the unit protocol between July 1995 and December 2001. Women were assessed to be at low risk in accord with the unit protocol. Those who had antenatal and intrapartum care at Heatherwood Hospital and those who were transferred to the consultant unit for delivery were included in this study. We analysed the appropriateness of the structure of the unit with its medical staff input, reviewed the inclusion and exclusion criteria, analysed the perinatal and maternal mortality rates and evaluated the safety of this birth setting. We have had a total of 5468 women delivered at this low-risk maternity unit since the unit was opened. Approximately 1950 women were transferred to consultant care during this period. The intrapartum transfer in the first 18 months was 7.9%. However, since 1997 it has been static at 2.7% as confidence has grown in this model of care. The antenatal transfer rate has been static around 23%. Our emergency caesarean section rate was around 6% and the normal delivery rate was around 85%. For the first time we noted a rise in the emergency caesarean rate in 2001 at 9.5%. There were no maternal deaths. We had no serious postpartum complications accounting for long-term maternal morbidity. The antepartum stillbirths accounted for the majority of the perinatal mortality for 19/23 babies. Intrauterine growth retardation accounted for 4/23 babies in this group. The perinatal mortality rate in this low-risk population was 4.2 per 1000 total births and the stillbirth rate was 3.6 per 1000 total births. We conclude that this birth setting is safe to deliver low-risk women with less intrapartum intervention and a low transfer rate and should be setting an example for any future similar birth centre in this country.

Diagnostic laparoscopy

Since the early part of the 20th century, diagnostic laparoscopy has become an important tool in the armamentarium of surgeons and gastroenterologists alike. Its indications have expanded from initial attempts at tamponading internal hemorrhage to avoidance of unnecessary laparotomies with accurate staging of malignancies, treatment of a multitude of intra-abdominal pathologies, and even as a resource for evaluating blunt abdominal trauma and chronic abdominal pain. Its accuracy has been demonstrated in the evaluation of chronic liver diseases, in comparison with other diagnostic modalities. Many further technical advances have been introduced in recent years. Gastroenterology training programs should include formal diagnostic laparoscopy training as part of their curriculum.

Nitrogen and Phosphorus Flux Rates from Sediment in the Lower St. Johns River Estuary

Internal cycling of nutrients from the sediment and water column can be an important contribution to the total nutrient load of an aquatic ecosystem. Our objective was to estimate the internal nutrient loading of the Lower St. Johns River (LSJR). Dissolved reactive phosphorus (DRP) and ammonium (NH(4)-N) flux from sediments were measured under aerobic and anaerobic water column conditions using intact cores, to estimate the overall contribution of the sediments to P and N loading to the LSJR. The DRP flux under aerobic water column conditions averaged 0.13 mg m(-2) d(-1), approximately 37 times lower than that under anaerobic conditions (4.77 mg m(-2) d(-1)). The average NH(4)-N released from the anaerobic cores (18.03 mg m(-2) d(-1)) was also significantly greater than in the aerobic cores for all sites and seasons, indicating the strong relationship between nutrient fluxes and oxygen availability in the water column. The mean annual internal DRP load was estimated to be 330 metric tons (Mg) yr(-1), 21% of the total P load to the river, while the mean annual internal load of NH(4)-N was determined to be 2066 Mg yr(-1), 28% of the total N load to the LSJR estuary. As water resource managers reduce external loading to the LSJR the frequency of anaerobic events should decline, thereby reducing nutrient fluxes from the sediment to the water column, reducing the internal loading of DRP and NH(4)-N. Results from this study demonstrate that the internal flux of nutrients from sediments may be a significant portion of the total load and should be accounted for in the total nutrient budget of the river for successful restoration.

Metastasising pituitary neuroendocrinal tumour with peptide secretion

A 26-year-old male presented with prolactin-secreting invasive pituitary macroadenoma, which was partially excised with right pterional craniotomy. Post-operative computerized tomography revealed persistence of the tumour and hence he was started on oral bromocriptine therapy. His therapeutic compliance was poor. Seven years later he presented with further increase in size of the pituitary macroadenoma with hepatic and gastric metastasis. Upper gastrointestinal endoscopic biopsy of the metastatic lesions and immunohistochemical staining diagnosed it as a neuroendocrinal tumour with peptide secretion. He was initially treated with oral bromocriptine alone and later along with octreotide.

Nitrification and denitrification rates of Everglades wetland soils along a phosphorus-impacted gradient

Little information is available on the effect of phosphorus (P) enrichment on nitrogen (N) biogeochemical cycling in wetland soil. Of particular importance are the coupled nitrification-denitrification reactions that regulate the microbially mediated loss of N from wetland systems. Soils from the northern Florida Everglades have been affected by P loading from surface waters over the past 40 years. Elevated P levels have been show to have an effect on the size and activity of the microbial pool and a decrease in the N to P ratio of the microbial biomass. The objective of the study was to determine if P enrichment in soils affected microbial activities related to nitrification and denitrification in these flooded, peat soils. Potential nitrification rates of soil and detritus were determined using constantly stirred reactors under aerobic conditions while denitrification rates were determined from anaerobic incubations of slurry. Nitrification rates showed two distinct linear phases, a slower initial rate, signifying activity of nitrifiers present, followed by a sharp increase in the NH4+ conversion rate indicative of maximum potential rates. Initial rates of nitrification were highest in the surficial detrital layer decreasing with soil depth and did not correlate to soil total P. The potential rates of nitrification were 13 times greater than the initial rates. Potential denitrification rates were highest in the detritus and 0- to 10-cm soil interval with significantly lower values in the 10- to 30-cm soil interval, significantly correlated to total P of the soil. A significant (P < 0.01) relationship was seen between potential denitrification rates and soil total P suggesting an increased rate of N removal from P-enriched regions of the northern Everglades.

Effects of ultraviolet-B radiation on cotton (Gossypium hirsutum L.) morphology and anatomy

Cotton (Gossypium hirsutum L.) crop, cultivated between 40 degrees N and 40 degrees S, is currently experiencing 2-11 kJ m-2 d-1 of UV-B radiation. This is predicted to increase in the near future. An experiment was conducted to study the effect of enhanced UV-B radiation on vegetative and reproductive morphology and leaf anatomy of cotton in sunlit, controlled environment chambers. From emergence to harvest, cotton plants were exposed to 0, 8 or 16 kJ m-2 d-1 of UV-B in a square wave approach for 8 h from 0800 to 1600 h. Changes in plant height, internode and branch length, mainstem node number, leaf area, length and area of petals and bracts, and anther number per flower were recorded. Epidermal cell and stomatal density, stomatal index, leaf thickness, and epidermal, palisade and mesophyll tissue thickness were also measured. Initial chlorotic symptoms on leaves turned into necrotic patches on continued exposure to enhanced UV-B. Exposure to high UV-B reduced both vegetative and reproductive parameters and resulted in a smaller canopy indicating sensitivity of cotton to UV-B radiation. Enhanced UV-B radiation increased epicuticular wax content on adaxial leaf surfaces, and stomatal index on both adaxial and abaxial leaf surfaces. Leaf thickness was reduced following exposure to UV-B owing to a decrease in thickness of both the palisade and mesophyll tissue, while the epidermal thickness remained unchanged. The vegetative parameters studied were affected only by high levels of UV-B (16 kJ m-2 d-1), whereas the reproductive parameters were reduced at both ambient (8 kJ m-2 d-1) and high UV-B levels. The study shows that cotton plants are sensitive to UV-B at both the whole plant and anatomical level.

Effects of system variables on surfactant enhanced electrokinetic removal of polycyclic aromatic hydrocarbons from clayey soils

Numerous polycyclic aromatic hydrocarbon (PAH)-contaminated sites threaten public health and the environment because PAHs are commonly toxins, mutagens, and/or carcinogens. PAHs are hydrophobic and resistant to degradation; therefore, conventional remediation methods are often costly or inefficient, especially when the PAHs are present in low permeability clayey soils. Electrokinetically enhanced in-situ oil flushing is an innovative technology that has the potential to greatly increase soil-solution-contaminant interaction and remedial efficiency, even under low permeability soil conditions. Although this technique is promising, many system variables may affect remedial efficiency, such as the surfactant concentration, pH control and voltage gradient. The objective of this investigation was to evaluate the effects of these system variables. Bench-scale electrokinetic experiments were conducted using various operating conditions, which included deionized water or a 3% or a 5% surfactant concentration flushing solution. Additional tests were also conducted using the 5% surfactant concentration along with a higher pH solution or a larger voltage gradient. The experiments employing the surfactant flushing solution had a lower electroosmotic flow but exhibited greater contaminant desorption, solubilization and migration. The benefits of using a higher pH solution or a larger voltage gradient were difficult to discern because changing these process variables did not significantly improve remedial efficiency. Overall, the results indicated that the surfactant flushing solution was advantageous for treating the soil near the anode region, but contaminant migration was limited by changes in the soil and/or solution chemistry that occurred with time and/or distance from the anode.

Potential internal loading of phosphorus in a wetland constructed in agricultural land

Wetland construction on agricultural or dairy lands could result in solubilization of phosphorus (P) stored in soils and release to the water column. To study the extent of P flux during the start-up period of a constructed wetland, intact soil-cores from areas used for dairy operations, in Okeechobee, Florida, USA were obtained and flooded with adjacent creek water. In the first 28-day hydraulic-retention period, P concentration in the water column increased several fold due to rapid P flux from impacted soils. A continuous decrease in P flux to the water column until the third hydraulic retention cycle (initial influent P concentration 0.2 mgL(-1)), and constant thereafter suggest that the effect of initial influent P upon long-term P flux from soils could be limited. The initial release maybe due to high concentration of labile P in impacted soils; however, slow dissolution of relatively stable P pools could maintain a steady flux, well above of that observed from non-impacted soils. Water soluble P along with double acid-extractable magnesium explained 76% of the variability in cumulative P flux to the water column. Apparently, co-occurrence of active adsorption-desorption phenomena due to independent maintenance of equilibrium by individual P compounds regulates P dynamics of the water column. The results indicated that equilibrium P concentration of the water column of the wetland would be above 1.3 mgL(-1), which is well above the targeted P level in the water column of the Lake Okeechobee, one of the main water bodies in the area (0.04 mg PL(-1)). This suggests construction of wetlands in agricultural lands could result to substantial internal P loading. However, preventative measures including chemical amendments, establishment of vegetative communities or flushing the initially released P may potentially stabilize the system, and maintain P removal efficiency.