GC/MS analysis of volatile organic selenium species produced during phytoremediation.

The use of plants and microorganisms that can naturally volatilize selenium and remove it from the soil or water has been studied with promising results. It has been shown that selenium can be removed from soils by plant uptake and accumulation, plant volatilization, and removal in the rhizosphere. Preliminary studies indicated that Hydrilla verticillata Royle removed selenium by means of phytovolatilization. Therefore, studies were conducted to examine the volatile products produced during phytoremediation of selenium by hydrilla. Samples were obtained and analyzed by GC/MS. Organoselenium compounds found were dimethyl selenide, dimethyl diselenide, and diethyl diselenide.

Blood pressure changes during barium enema.

AIMS: To document blood pressure changes during barium enema examination and to determine at what point in the examination changes are likely to occur. METHODS AND RESULTS: Blood pressure measurements were taken at seven points during the course of barium enema examination in 107 consecutive patients. We found that patients over the age of 60 years had statistically significant decreases in blood pressure when they were stood up during the course of the examination. Many of these patients were asymptomatic. Patients who had symptoms (15/107, 14%) when standing up had a degree of hypotension. The duration of barium enema examination is longer in those patients who experience symptoms. CONCLUSION: During a barium enema examination hypotension occurs at the point of standing up more frequently in patients over 60 years and in those who suffer symptoms at this time. Patients who fall into one of these groups should be considered at risk of fainting at this point in the examination. A modified technique to avoid standing should be considered in at-risk patients. Roach, S. C.et al. (2001). Clinical Radiology56, 393-396.

Lysis of Gymnodinium breve by cultures of the green alga Nannochloris eucaryotum.

Laboratory cultures of Florida's red tide organism, Gymnodinium breve, were killed by the green alga Nannochloris eucaryotum. Studies involved organism-organism interaction as well as organism-cell-free culture (N. eucaryotum) interaction. Both studies demonstrated that N. eucaryotum adversely affected Florida's red tide organism. The lysis has been attributed to compounds called APONINs (apparent oceanic naturally occurring cytolins). N. eucaryotum crude APONIN was extracted from cell-free cultures, partially purified and fractionated. The fractions were bioassayed against G. breve, and 'fingerprints' of the deleterious fractions were obtained.

Environmental impacts of phosphogypsum vs. borrow pits in roadfill construction.

A comparison was performed of the environmental impacts of using phosphogypsum versus conventional fill materials (e.g., from borrow pits) for road construction. The study compared a hypothetical roadway with an actual roadway in Florida; the two facilities differed only in that phosphogypsum was employed as fill material instead of conventional materials. The effect of the two construction approaches on the plant and animal communities was considered, as was the impact on the surface and ground water. A summary was made of the comparative impacts, and a comparison matrix was constructed using integral numbers to depict impacts ranging from -5 (most impact) to 0 (none) to + 5, showing most benefit of the part of the project on a given resource. Values were subjective, based upon investigators' experience. Four categories (plant and animal communities, water quality, water resources, and air quality) were considered. The cumulative total was +12 for phosphogypsum and -6 for conventional fill material.

Bioassays of APONIN-3 and -4 with rabbit erythrocytes.

Rabbit erythrocytes in methanolic phosphate medium were used to bioassay the activity of authentic samples of methyl stearate and methyl palmitate (in 10% methanol:90% water, v/v), which had been identified as apparent oceanic naturally occurring cytolins (APONIN-3 and -4) produced by Nannochloris oculata. The two natural products are notable for cytolytic activity toward the unarmoured dinoflagellate, Gymnodinium breve Davis, an organism responsible for red tides consisting of harmful algal blooms in the Gulf of Mexico and along the eastern coast of the United States. Bioassays were done with heparinized rabbit blood. The absorbance at 540 nm was observed for 15 min in comparison with a sample treated with haemolysing agent. The results indicated that at reasonable concentrations of 1-10 ppm, neither was a haemolysin, although such concentrations caused cytolysis of G. breve cultures.

Localized perforation into the transverse mesocolon demonstrated during barium enema--rare but benign.

We report two cases demonstrating the presence of gas in the transverse mesocolon following asymptomatic perforation, shown during barium enema examination. The appearances, diagnosis and successful conservative management are described.

Small bowel phytobezoar mimicking presentation of Crohn's disease.

A case of small bowel phytobezoar formed from unusual ingested vegetation is described. The patient presented with recurrent subacute obstruction and a right iliac fossa mass mimicking the presentation of Crohn's disease. None of the usual gastrointestinal disorders that predispose to bezoar formation were present. The phytobezoar passed spontaneously following small bowel enema and colonoscopy. It is possible that relaxation of the gut secondary to the antispasmodics administered at investigation or the physical disturbance during these procedures enabled migration through the ileocecal valve. Antispasmodics may be of use in the conservative management of bezoars obstructing otherwise normal bowel.

The influence of type of tube and experience of the operator on performance of small bowel enema.

Seventy patients underwent small bowel enema (SBE) to assess the influence of experience of the radiologist on the ease of jejunal intubation and the adequacy of SBE using two types of tubes. Comparing intubation time, intubation screening time, total screening time and total room time, we conclude that jejunal intubation is achieved easily, in a reasonable time with both types of tube, by all grades of radiologist, although the experienced operator using the Silk tube achieved intubation in a significantly shorter time. Overall patient acceptability was satisfactory (75%) but was better using the Silk tube, with which entero-gastric reflux and vomiting were less.

Enhancement of tumor radiation response by the combination of a perfluorochemical emulsion and hyperbaric oxygen.

The presence of radioresistant hypoxic cells in tumors is believed to be one of the limiting factors in achieving local tumor control by radiotherapy. Treatment with hyperbaric oxygen during irradiation has been shown to improve the radiation response of many solid tumors in rodents and of some tumors in patients. Intravenous administration of perfluorochemical emulsions combined with oxygen breathing at atmospheric pressure has also been shown to improve the radiation response of several rodent tumors. Theoretical considerations suggest that the combination of a perfluorochemical emulsion and hyperbaric oxygen should be significantly more effective than either agent alone. This hypothesis was tested by examining the radiation response of BA1112 rhabdomyosarcomas growing in WAG/rij-Y rats. Treatment with a perfluorochemical emulsion, Fluosol-DA, plus hyperbaric oxygen (3 Atmospheres O2) significantly increased the radiation response of the malignant cells in these solid tumors. The observed changes in the tumor cell survival curve suggest that the combination of Fluosol-DA and HBO decreases the proportion of severely hypoxic cells in the tumor to less than 1.5% of the original value. The effect of the Fluosol-DA dose and the duration of pretreatment with HBO are described.

Perfluorochemicals and hyperbaric oxygen in radiation therapy.

It has been postulated that tumors contain hypoxic cells of decreased radiation sensitivity, which limit curability with radiation therapy. Hyperbaric oxygen has been used in an attempt to improve tumor oxygenation. The nature of the oxygen concentration-radiation sensitivity relationship (oxygen increases the slope of the radiation cell survival curve) suggests that a small number of hypoxic cells, as few as one in one million, would limit tumor curability. Oxygen moves by diffusion from the capillary into the tumor. An increase in partial pressure in the capillary will increase the effective diffusion distance. To improve tissue oxygenation effectively the partial pressure of oxygen in blood must be significantly increased throughout the length of the capillary, in particular at the venous end. Theoretical considerations indicate that hyperbaric oxygen as presently used in radiation therapy, 3 ATA, would lead to only marginal improvement. PartO2 may be as much as 0.8 atm below that of the inspired gas; this plus the consumption of oxygen along the length of the capillary lead to predictions of values for PEnd CapO2 of less than twice normal. Such considerations explain the rather limited success of hyperbaric oxygen with radiation therapy. Thus it is unnecessary to postulate an absence of hypoxic cells to explain this clinical observation. In the presence of perfluorocarbon micelles the non-hemoglobin-bound oxygen carrying capacity of blood is significantly increased. Theoretical considerations predict that the difference between PartO2 and PO2 of the inspired gas should be decreased. Furthermore, the nonhemoglobin-bound oxygen carrying capacity should be adequate to satisfy tissue consumption requirements without unloading hemoglobin, thereby avoiding the "PO2 buffering effect of hemoglobin" and permitting a significant increase in PO2 throughout the capillary length. This effect has been demonstrated using a rodent tumor model.

Effect of aponin, a substance from a green alga Nannochloris species, on the spore germination of two fungi.

Fungistasis which occurs in soil has also been reported to exist in seawater. Nannochloris sp. (Chlorophyta) found along the west coast of Florida, has been shown to elaborate a compound which is cytolytic towards Ptychodiscus brevis, the Florida red tide organism. Aponin, a chloroform extract containing the cytolytic compound or compounds, was tested on the spore germination of two fungi, Dendryphiella salina, a facultative marine organism and Curvularia sp. a terrestrial one. Aponin was stimulatory towards D. salina at all concentrations tested, while Curvularia sp. was stimulated at the highest concentration used but inhibited at the lower concentrations. The culture age of the two fungi did not alter the relative sensitivity of both fungi towards aponin but the germination percentage of Curvularia sp. was affected by the culture age. An aqueous extract of Nannochloris sp. was also tested on the two fungi and was shown to be inhibitory to both. The results seem to indicate that more than one compound from Nannochloris sp. is capable of affecting spore germination indicating that this alga might be playing a role in the reported fungistasis in seawater. Gulf seawater was tested and found to have little if any fungistatic activity.

Short-term effects on Artemia salina of aponin and Gomphosphaeria aponina in unialgal cultures and in mixed cultures with gymnodinium breve.

Previous investigations showed that the natural marine substance aponin, produced by the blue-gree alga Gomphosphaeria sponina, was cytolytic towards Florida's red tide organism, Gymnodinium breve. As part of a study of the aponin-alga biological interactions, the effects of unialgal (G. aponina) and mixed cultures (G. aponina + G. breve) on the viability of artemia salina were investigated. Two contrasting effects were observed in mixed cultures: survival of A. salina was promoted in low G. aponina populations, while enhanced toxicity of G. breve to A. salina occurred at higher culture populations. Unialgal G. aponina cultures exerted no adverse effects on A. salina. The apparent protective effect is thought to result from the observed change in G. breve morphology (motile to sessile); toxicity was the result of enhanced toxin release by cytolyzed G. breve cells. In dose-response studies, aponin exhibited no adverse effect on A. salina at concentrations (1 unit) that were deleterious to G. breve. However, at higher applied levels (4--6 units), mortality was substantial (greater than 70%) after 48 hr of incubation. Probit analysis yielded an apparent LD50 of 2.3 units, where 1 unit was that amount required to cytolyze 50% of the G. breve cells (2000 cells/ml) after 20 hr of incubation.

Effects of microwaves on organisms. Ptychodiscus brevis--Gomphosphaeria aponina interactions.

The two referenced organisms have been subjected to microwave irradiation (2,450 MHz CW). Initial experiments indicated no statistically significant loss of cell numbers as a result of simple temperature rise (6 degrees C) or experimental manipulation. Cell survival for P. brevis one week after irradiation was related to total energy absorbed, not power level used. Over a 48 h period, a first-order decrease in cell numbers was observed. All cells were destroyed at a threshold level of 0.1 kJ/cm3. In contrast, the blue-green alga G. aponina in log phase of growth showed no loss of cells. In the presence of G. aponina, P. brevis suffered cell lysis, though G. aponina thrived. Irradiation of the mixed cultures appeared to enhance the lysis effect.

The influence of Gomphosphaeria aponina on the growth of Gymnodinium breve and the effect of aponin on the ichthyotoxicity of Gymnodinium breve.

Cells of the marine blue-green alga Gomphosphaeria aponina survive in mixed culture with the marine dinoflagellate, Gymnodinium breve (the Florida red tide organism), but G. breve cells lysed within 4-7 days. It has been established that the cytolytic effect of G. aponina, not nutrient competition, is responsible for the decrease in number of cells. The material elaborated by G. aponina has been termed aponin and has been extracted from the cells. The effect of aponin on the ichthyotoxicity of G. breve cultures was measured using Poecilia sphenops, adapted to sea water, as the assay organism. Aponin is not ichthyotoxic toward P. sphenops, though this material, when incubated with G. breve cultures does destroy the cells and increases the ichthyotoxicity of the cultures. At certain concentrations of aponin, the ichthyotoxicity of G. breve cultures appeared to be mitigate d.

Growth response of the marine blue-green alga, Gomphosphaeria aponina, to inorganic nutrients and significance to management of Florida red tide.

A bioactive isolate from the blue-green alga Gomphosphaeria aponina is cytolytic towards the dinoflagellate, Gymnodinium breve, Florida's red tide organism. Batch and continuous cultures of G. aponina were used to determine nutrient limitation and to optimize mass-culture conditions. Iron and inorganic carbon were growth limiting; first-order saturation kinetics were observed for both substrates. For Fe3+, kinetic parameters were: Ks = 62 +/- 9 microgram 1(-1), and Ke max = 2.14 days-1. Maximum growth was observed at 150 micrograms Fe3+1(-1), with minimal growth below 10 microgram 1(-1). Cells colonized with increasing Fe3+ supplements, and time to reach maximum culture populations was inversely related to the concentration. For HCO3-,Ks = 62 +/- 4 mg1(-1) and Ke max = 1.3 day-1. Additions of NH4+ up to 200 micrograms 1(-1) were not stimulatory, whereas at 1.0 mg 1(-1) levels, Ke was 50% greater than for NO3- enriched medium. Concentrations greater than 25 micrograms PO4(3-) 1(-1) were stimulatory. However, at 1 mg1(-1), growth was less than in controls. Comparison of similar data available for G. breve would suggest that the inorganic nutrient requirements of G. aponina were minimal. Potential for natural control of G. breve by G. aponina is perhaps related to the efficiency of contact of the two organisms.