SIMAZINE-INDUCED INHIBITION IN PHOTOACCLIMATED POPULATIONS OF ANABAENA CIRCINALIS (CYANOPHYTA)1

The effects of the triazine herbicide, simazine, on photosynthetic oxygen evolution and growth rate in photoacclimated populations of Anabaena circinalis Rabenhorst were investigated. Chemostat populations were acclimated to photon flux densities (PFDs) of 50, 130, and 230 μmol·m^?2·s^?1 of photosynthetic active radiation (PAR), Decreases in chlorophyll a (Chl a). c-phycocyanin (CPC), and total carotenoid (TCar) contents and CPC: Chl a and CPC: TCar ratios of populations coincided with increasing PFD, Polynomial regression models that characterize inhibition of photosynthesis for populations acclimated to 50 and 130 μmol photons·m^?2·s^?1 PAR were distinct from the model for populations acclimated to 230 μmol photons·m^?2·s^?1 PAR. Simazine concentrations that, depressed oxygen evolution 50% compared to controls decreased with increasing PFD. Increases and decreases in both biomass and growth rate coincided with increasing PFD and simazine concentration, respectively. Simazine concentrations that depressed growth rate 50% compared to controls increased with decreasing PFD. The differences in photosynthetic and growth inhibition among photoacclimated populations indicate that sensitivity to photosystem II inhibitors is affected by alterations in pigment contents.     

Production of the taste/odor-causing compound,trans-2,cis-6-nonadienal,within the Synurophyceae

Although several species of the Synurophyceae have been associated with taste and odor problems in potable water supplies, electron microscopic-based field studies linked problematic blooms only toSynura petersenii Korshikov. Eventually, the organic compoundtrans-2,cis-6-nonadienal was implicated to cause the associated cucumberlike odors. The objective of this study was to survey unialgal cultures of various Synurophycean species for the occurrence oftrans-2,cis-6-nonadienal. The compound was detected throughout a 24-day growth assay with aS. petersenii isolate, but was not detected in an identical assay withSynura sphagnicola (Korshikov) Korshikov. In separate 24-day cultures,trans-2,cis-6-nonadienal was detected in two isolates from theS. petersenii species complex, but was not detected in isolates of twoMallomonas or fourSynura taxa not from theS. petersenii complex. These results support the hypothesis that production oftrans-2,cis-6-nonadienal is unique to taxa within theS. petersenii complex. When contrast-enhancing optics and specific specimen preparation techniques are employed, light microscopy can be used to distinguish taxa in theS. petersenii complex from all other Synurophycean taxa. These methods are suggested as an efficient way to monitortrans-2,cis-6-nonadienal-producing taxa in potable water supplies.Author for correspondence     

Flow cytometric analysis of paraffin-embedded material in human gastric cancer

Flow cytometric DNa analysis was performed on formalin-fixed, paraffin-embedded samples obtained by gastroscopic biopsy from 9 patients with histologically normal gastric mucosa (36 specimens) and by radical gastrectomy from 42 cases of human gastric cancer (120 specimens). Ploidy patterns and the distribution of cells in the different cell cycle phases were estimated, and the results were correlated with the histologic and clinical features. All samples of normal mucosa showed a diploid modal DNA content whereas DNA aneuploidy was encountered in 71.4% of the gastric tumors. The correlation between aneuploidy and histologic malignancy grading was statistically significant: aneuploidy was found in 36.4% of highly differentiated (grade 1 and grade 2) tumors and in 75.0% of poorly differentiated (grade 3) tumors (P less than .05). The percentage of cells in S-phase in normal gastric mucosa (median: 5.0%) was lower than that in the tumors (median: 11.3%) (P less than .05). There was a trend for grade 3 tumors to have higher median values (median: 13.4%) than grade 1 and 2 tumors (median: 9.3%); however, this was not statistically significant. An aneuploid DNA pattern was associated with a poorer prognosis, both in early and in advanced stages of gastric tumors, while proliferative activity did not correlate with postoperative survival.     

EVALUATING THE RELATIONSHIP BETWEEN PHOTOPIGMENT SYNTHESIS AND 2-METHYLISOBORNEOL ACCUMULATION IN CYANOBACTERIA

  The relationship between photopigments and the terpene-derived secondary metabolite, 2-methylisoborneol (MIB), was analyzed in photoacclimated cultures of Pseudanabaena articulata Skuja throughout growth, during the diel cycle, and following chemical-induced inhibition of the isoprenoid pathway. Accumulation of MIB coincided with the accumulation of lipophilic and phycobilin pigments during the early to mid-exponential portion of the growth cycle with the greatest accumulation of MIB during the late-exponential phase. Cellular release of MIB occurred as culture populations entered mid- to late-logarithmic phase of growth and was greatest in irradiance-stressed cultures. The greater correspondence of MIB accumulation with photopigments was seen in cultures transferred from a 12:12 h LD photoperiod alone and the consistent relationship between MIB and photopigment accumulation under varying irradiance suggested a photopigment-dependent regulation for MIB synthesis. However, the consistent allocation of carbon into MIB during instances of phytofluene and tetrapyrrole biosynthetic inhibition within P. articulata and Oscillatoria perornata Skuja indicated that MIB accumulation is not limited by isopreniod-carbon availability and does not appear to serve as an "overflow" product. Rather, MIB accumulation simply appears to reflect overall carbon accumulation resulting from increased cell metabolism.     

The effects of ethanol on the responses of the vascular musculature to norepinephrine

Intravenous infusion of ethanol (EtOH) (up to 0.1 ml kg-1 min-1) does not modify the blood pressure in conscious rabbits. In this range of doses, EtOH brings about an increase of the pressure responses induced by norepinephrine (NE) with respect to values obtained in the absence of EtOH. Similar experiments have been performed on the isolated rat tail artery: EtOH perfusion does not modify the basal tone of the preparation up to 2% concentration, while the contractile response to NE administration is potentiated. The supersensitivity of the arteries to NE induced by EtOH, is a function of EtOH concentration and can be represented by a bellshaped curve reaching the maximal value at 1% EtOH, whereby concentrations larger than 2% induce an inhibition of NE activity. The present experiments suggest that the potentiation of the contractile effects of NE induced by EtOH might be related to an enhancement of the rate of calcium transport due to the increase in cell membrane plasticity induced by EtOH.     

In vitro and in vivo studies of boron neutron capture therapy: boron uptake/washout and cell death

Boron neutron capture therapy (BNCT) is a binary radiotherapy based on thermal-neutron irradiation of cells enriched with (10)B, which produces α particles and (7)Li ions of short range and high biological effectiveness. The selective uptake of boron by tumor cells is a crucial issue for BNCT, and studies of boron uptake and washout associated with cell survival studies can be of great help in developing clinical applications. In this work, boron uptake and washout were characterized both in vitro for the DHDK12TRb (DHD) rat colon carcinoma cell line and in vivo using rats bearing liver metastases from DHD cells. Despite a remarkable uptake, a large boron release was observed after removal of the boron-enriched medium from in vitro cell cultures. However, analysis of boron washout after rat liver perfusion in vivo did not show a significant boron release, suggesting that organ perfusion does not limit the therapeutic effectiveness of the treatment. The survival of boron-loaded cells exposed to thermal neutrons was also assessed; the results indicated that the removal of extracellular boron does not limit treatment effectiveness if adequate amounts of boron are delivered and if the cells are kept at low temperature. Cell survival was also investigated theoretically using a mechanistic model/Monte Carlo code originally developed for radiation-induced chromosome aberrations and extended here to cell death; good agreement between simulation outcomes and experimental data was obtained.     

Laparoscopic Left Liver Sectoriectomy of Caroli's Disease Limited to Segment II and III

Caroli''s disease is defined as a abnormal dilatation of the intra-hepatica bile ducts: Its incidence is extremely low (1 in 1,000,000 population) and in most of the cases the whole liver is interested and liver transplantation is the treatment of choice. In case of dilatation limited to the left or right lobe, liver resection can be performed. For many year the standard approach for liver resection has been a formal laparotomy by means of a large incision of abdomen that is characterized by significant post-operatie morbidity. More recently, minimally invasive, laparoscopic approach has been proposed as possible surgical technique for liver resection both for benign and malignant diseases. The main benefits of the minimally invasive approach is represented by a significant reduction of the surgical trauma that allows a faster recovery a less post-operative complications.This video shows a case of Caroli s disease occured in a 58 years old male admitted at the gastroenterology department for sudden onset of abdominal pain associated with fever (>38C° ), nausea and shivering. Abdominal ultrasound demonstrated a significant dilatation of intra-hepatic left sited bile ducts with no evidences of gallbladder or common bile duct stones. Such findings were confirmed abdominal high resolution computer tomography. Laparoscopic left sectoriectomy was planned. Five trocars and 30° optic was used, exploration of the abdominal cavity showed no adhesions or evidences of other diseases.In order to control blood inflow to the liver, vascular clamp was placed on the hepatic pedicle (Pringle s manouvre), Parenchymal division is carried out with a combined use of 5 mm bipolar forceps and 5 mm ultrasonic dissector. A severely dilated left hepatic duct was isolated and divided using a 45mm endoscopic vascular stapler. Liver dissection was continued up to isolation of the main left portal branch that was then divided with a further cartridge of 45 mm vascular stapler.At his point the left liver remains attached only by the left hepatic vein: division of the triangular ligament was performed using monopolar hook and the hepatic vein isolated and the divided using vascular stapler.Haemostatis was refined by application of argon beam coagulation and no bleeding was revealed even after removal of the vascular clamp (total Pringle s time 27 minutes).Postoperative course was uneventful, minimal elevation of the liver function tests was recorded in post-operative day 1 but returned to normal at discharged on post-operative day 3.Open in a separate windowClick here to view.^{(26M, flv)}     

EFFECTS OF SOIL WATERLOGGING ON THE ENERGY STATUS AND DISTRIBUTION OF SALIX NIGRA AND S. EXIGUA (SALICACEAE) IN THE ATCHAFALAYA RIVER BASIN OF LOUISIANA

The influence of soil waterlogging on the distribution and energy status of Salix nigra and S. exigua were studied in the field and laboratory. Differential flooding in natural stands of Salix spp. and under controlled conditions in the greenhouse demonstrated that S. nigra was more tolerant of waterlogged soil conditions than was S. exigua. Salix nigra exhibited a significantly higher leaf energy status and greater ability to oxidize waterlogged soil when flooded than did S. exigua. However, S. exigua appeared to be more tolerant of moisture stress than S. nigra as indicated by the significantly higher leaf resistances to water vapor exchange and higher leaf water potentials of S. exigua. These data support the theory that the reason S. nigra inhabits lower elevation sites than S. exigua in the Atchafalaya River Basin may be the differential tolerance of these two species to soil waterlogging on one extreme and moisture deficiencies on the other.