Advantageous characteristics of the diatom Chaetoceros gracilis as a sustainable biofuel producer

BACKGROUND

Diatoms have attracted interest as biofuel producers. Here, the contents of lipids and photosynthetic pigments were analyzed in a marine centric diatom, Chaetoceros gracilis. This diatom can be genetically engineered using our previously reported transformation technique and has a potential to produce valuable materials photosynthetically. Sustainable culture conditions for cost-effective production of biological materials under autotrophic conditions with atmospheric carbon dioxide were investigated in the laboratory. A large-scale, open-air culture was also performed.

RESULTS

Cell population doubling time was ~10 h under continuous illumination without CO₂ enrichment, and large amounts of triacylglycerols (TAG) and fucoxanthin accumulated under a wide range of salinity and nutrient conditions, reaching ~200 and 18.5 mg/L, respectively. It was also shown that C. gracilis produced high amounts of TAG without the need for nitrogen or silica deprivation, which is frequently imposed to induce lipid production in many other microalgae. Furthermore, C. gracilis was confirmed to be highly tolerant to changes in environmental conditions, such as salinity. The diatom grew well and produced abundant lipids when using sewage water or liquid fertilizer derived from cattle feces without augmented carbon dioxide. High growth rates (doubling time <20 h) were obtained in a large-scale, open-air culture, in which light irradiance and temperature fluctuated and were largely different from laboratory conditions.

CONCLUSIONS

The ability of this microalga to accumulate TAG without nutrient deprivation, which incurs added labor, high costs, and complicates scalability, is important for low-cost industrial applications. Furthermore, its high tolerance to changes in environmental conditions and high growth rates observed in large-scale, open-air culture implied scalability of this diatom for industrial applications. Therefore, C. gracilis would have great potential as a biofactory.

Influences of Helicobacter pylori on serum pepsinogen concentrations in dialysis patients

BACKGROUND

Patients with impaired renal function have been known to have elevated concentrations of serum pepsinogens, which are raised by Helicobacter pylori infection of the stomach. The present study was performed to examine the effect of H. pylori infection on serum pepsinogen concentrations in dialysis patients.

METHODS

Forty nine patients on dialysis and 48 subjects with no known kidney disease were examined for upper gastroduodenal endoscopy, H. pylori infection and serum concentrations of pepsinogen I and II. The status of H. pylori infection was evaluated from results of a urease test, histology and culture of biopsy specimens of the gastric mucosa. Serum pepsinogen levels were measured by radioimmunoassay.

RESULTS

Serum concentrations of pepsinogen I and II were elevated in the dialysis patients in comparison with those in the controls (277.4+/-24.2 vs 52.6+/-4.0 pg/ml, P<0.01 for pepsinogen I, and 30.2+/-2.9 vs 14.9+/-1.3 pg/ml, P<0.01 for pepsinogen II). In both the dialysis patients and controls, those with H. pylori infection had significantly higher concentrations of serum pepsinogen I and II and a lower ratio of pepsinogen I to pepsinogen II than those without infection. Among the controls, 15 of 25 subjects with atrophic gastritis had a pepsinogen I/pepsinogen II ratio < or = 3.0, while only two out of 17 patients on dialysis fell into this range.

CONCLUSIONS

We conclude that H. pylori status should be taken into account when serum pepsinogen concentrations are evaluated in dialysis patients.

Eradication of Helicobacter pylori restores elevation of serum gastrin concentrations in patients with end-stage renal disease

In order to explore the role of Helicobacter pylori (H. pylori) infection in hypergastrinemia in patients on dialysis, the changes in serum gastrin concentration were examined before and after eradication treatment for H. pylori. Twenty-seven patients on dialysis were treated for the eradication of H. pylori. Fasting serum gastrin concentrations were measured by a radioimmunoassay which detects gastrin 17. Ammonia and pH levels of the gastric juice were also measured. The serum gastrin concentrations were significantly decreased following eradication of H. pylori, and the mean value reached the normal range. The restoration of hypergastrinemia was associated with marked reductions of gastric juice ammonia and pH levels. In contrast, patients in whom H. pylori was not eradicated showed no changes in these parameters. In conclusion, the elevation of the fasting serum gastrin 17 concentration seen in dialysis patients appeared to be attributable to H. pylori infection in the stomach.

Eradication of Helicobacter pylori in patients with end-stage renal disease under dialysis treatment

The efficacy and safety of combination therapy with amoxicillin, lansoprazole, and plaunotol for the eradication of Helicobacter pylori in patients on dialysis were evaluated. The study subjects comprised 15 dialysis patients in whom H pylori had been found in the gastric mucosa. The patients were given 500 mg amoxicillin once a day for 3 weeks, 30 mg lansoprazole once a day for 8 weeks, and 80 mg plaunotol three times a day for 24 weeks. Endoscopy was performed on entry and at 4 and 24 weeks after cessation of amoxicillin. The concentrations of serum gastrin and gastric juice ammonia also were measured. Fourteen patients completed the treatment protocol, one having dropped out because of nausea and diarrhea. H pylori was eradicated in 11 of the 14 patients 4 weeks after the end of amoxicillin therapy (eradication rate, 78.6%). All but one patient was free of H pylori 24 weeks after the amoxicillin was discontinued. Patients who became negative for H pylori had significantly decreased serum gastrin and gastric juice ammonia concentrations. Our findings indicate that a combination of amoxicillin, lansoprazole, and plaunotol can be used to eradicate H pylori in patients on dialysis.

Cloning of a novel ubiquitin-conjugating enzyme (E2) gene from the ciliate Paramecium tetraurelia

We isolated a 1.7 kb gene (UbcP1) for a ubiquitin-conjugating enzyme from a P. tetraurelia cDNA library and sequenced it. Its deduced polypeptide sequence consists of 425 amino acid residues (48 kDa). The UbcP1 protein contains novel N- and C-terminal extensions in addition to a UBC domain, and within the UBC domain it shares low identity with sequences of other known E2s. A constructed phylogenetic tree suggests that the UbcP1 protein may represent a member of a distinct subfamily of E2s. Southern blot analysis showed that the N-terminal extension of the UbcP1 is conserved in P. multimicronucleatum.

[Eradication of Helicobacter pylori in patients with end-stage renal disease undergoing dialysis treatment]

The aim of the present study was to examine the efficacy and safety of combination therapy with amoxicillin (AMPC), lansoprazole, and plaunotol for the eradication of H. pylori in dialysis patients. The subjects consisted of 15 dialysis patients (10 men and 5 women, mean age of 56 +/- 2.4 years) in whom H. pylori was found in the stomach. H. pylori status was evaluated by histology, culture and rapid urease test with biopsy specimens of the gastric mucosa. The patients were treated with AMPC 500 mg once a day for 3 weeks, lansoprazole 30 mg once a day for 8 weeks and plaunotol 80 mg three times a day for 24 weeks. In addition, the concentrations of serum gastrin and gastric juice ammonia were measured. Fourteen patients completed the treatment schedule, while one discontinued treatment because of nausea and diarrhea. Among the 14 patients, H. pylori was eradicated in 11 without any side effects (eradication rate 78.6%). Concentrations of gastric juice ammonia and serum gastrin were reduced significantly in patients who became H. pylori-negative. The present study indicates that combination therapy with AMPC, lansoprazole and plaunotol is safe and efficient for the eradication of H. pylori in dialysis patients. The results also suggested that elevated concentrations of gastric juice ammonia and serum gastrin in dialysis patients can be attributed, at least in part, to H. pylori infection.

[Role of Helicobacter pylori in gastro-duodenal mucosal lesions in patients with end-stage renal disease under dialysis treatment]

It is known that Helicobacter pylori (H. pylori) plays an important role in gastritis and peptic ulcer disease in the general population. Although upper gastrointestinal mucosal lesions have been one of the most common complications in patients with chronic renal failure, quite few reports are available regarding the prevalence of H. pylori and its influence on the upper gastro-intestinal tract. The present study was conducted to examine whether H. pylori is involved in the pathogenesis of upper gastrointestinal mucosal lesions in dialysis patients. The subjects consisted of 43 dialysis patients with upper gastro-intestinal tract symptoms. Thirty-four patients without any known kidney disease were used as controls. Gastric mucosa and gastric juice were obtained endoscopically. For the determination of H. pylori, culture of biopsy specimens from the gastric mucosa and histopathological examination with hematoxylin-eosin stain were used. Concentrations of serum gastrin and gastric juice ammonia were also measured. H. pylori was observed in 53.5% of the dialysis group and 64.0% of the controls. Gastro-duodenal lesions in H. pylori-positive dialysis patients included atrophic gastritis, superficial gastritis, erosive gastritis, and gastric ulcer. In the dialysis group, ammonia concentrations in the gastric juice were higher in patients with H. pylori than in those without H. pylori (489.1 +/- 35.8 mu g/ml vs 67.0 +/- 19.2 mu g/ml, p < 0.001). The former value was also higher than that seen in the H. pylori-positive controls (152.4 +/- 18.7 mu g/ml, p < 0.01). Serum levels of gastrin were significantly higher in patients with H. pylori than in patients without H. pylori (ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between circadian periods and cellular activities in Paramecium bursaria

Paramecium bursaria shows a circadian rhythm of photoaccumulation: photoaccumulation is stronger during the day than at night. We obtained five strains of P. bursaria having different circadian periods under continuous light conditions, ranging from 20.9 to 27.9 h. Various physiological activities were compared in the cells of these strains. The periods of contractile vacuole contraction were in the range 10-15 s, which was almost proportional to the periods of the circadian rhythm in each strain. Swimming velocities were inversely proportional to the circadian period; i.e. swimming velocities were high in strains whose circadian periods were short. Resting membrane potential was more depolarized in strains with longer circadian periods. Finally, the membrane resistance of the resting state was reduced in proportion to the increase of the circadian period. Such correlation between the cellular properties and the circadian period suggests that the circadian clock mechanism is associated with various physiological activities of the cell.

Hyperhomocysteinemia as a possible role for atherosclerosis in CAPD patients

It has been shown that hyperhomocysteinemia is a risk factor for atherosclerotic vascular disease. In this study, we measured total plasma homocysteine in continuous ambulatory peritoneal dialysis (CAPD) patients and evaluated its correlation with atherosclerosis. Subjects consisted of healthy volunteers, and hemodialysis (HD) and CAPD patients. Fluoro-HPLC was employed to estimate plasma levels of total homocysteine (Hcy). Plasma levels of total Hcy were significantly higher in the CAPD patients compared with the HD patients and controls. Atherosclerotic score (ASS) was calculated, and the correspondence with plasma levels of total Hcy was analyzed. There was a significant correlation between plasma levels of total Hcy and ASS in CAPD patients. However, plasma levels of total Hcy did not correlate with age, plasma vitamin B6 level, residual renal function, protein catabolic rate (PCR), or KT/V. Our present study suggests that elevated concentrations of total plasma Hcy might play a role in the development of atherosclerosis in CAPD patients.

A case of hematophagic histiocytosis associated with acute renal failure

The present report describes a rare case of hematophagic histiocytosis associated with acute renal failure. A 32-year-old woman was referred to us from a local hospital because of progressive deterioration of renal function, jaundice and a bleeding tendency. The physical findings at admission revealed hyperemic conjunctivae, gingival bleeding, hepatomegaly, and generalized myalgia. Laboratory data indicated a decrease in platelet count, azotemia and hyperbilirubinemia. Marked elevation of serum triglycerides and ferritin was also noted. Histiocyte proliferation with phagocytosis of erythrocytes and platelets was observed in a bone marrow aspirate. A renal biopsy specimen exhibited lesions generally observed in acute tubular necrosis: degeneration and necrosis of tubular epithelial cells; round cell infiltration and edema in the interstitium; and unremarkable glomeruli. The serum titer to coxsackievirus B1 rose from < 4x at admission to 16x after recovery from the illness, suggesting that this virus may have been the causal organism of the accompanying infection. The patient's symptoms improved rapidly with supportive therapy, and complete restoration of renal function was achieved in 20 days. The morphological characteristics of the bone marrow aspirate and the clinical course were compatible with hematophagic histiocytosis.