Advanced Anaerobic Bioconversion of Lignocellulosic Waste for Bioregenerative Life Support Following Thermal Water Treatment and Biodegradation by Fibrobacter Succinogenes

The feasibility of nearly-complete conversion of lignocellulosic waste (70% food crops, 20% faecal matter and 10% green algae) into biogas was investigated in the context of a life support project. The treatment comprised a series of processes, i.e., a mesophilic laboratory scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor, a fiber liquefaction reactor employing the rumen bacterium Fibrobacter succinogenes and a hydrothermolysis system in near-critical water. By the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 l biogas g(-1) VSS (volatile suspended solids) added at a RT (hydraulic retention time) of 20-25 d was obtained. Biogas yields could not be increased considerably at higher RT, indicating the depletion of readily available substrate after 25 d. The solids present in the CSTR-effluent were subsequently treated in two ways. Hydrothermal treatment (T approximately 310-350 degrees C, p approximately 240 bar) resulted in effective carbon liquefaction (50-60% without and 83% with carbon dioxide saturation) and complete sanitation of the residue. Application of the cellulolytic Fibrobacter succinogenes converted remaining cellulose contained in the CSTR-effluent into acetate and propionate mainly. Subsequent anaerobic digestion of the hydrothermolysis and the Fibrobacter hydrolysates allowed conversion of 48-60% and 30%, respectively. Thus, the total process yielded biogas corresponding with conversions up to 90% of the original organic matter. It appears that particularly mesophilic digestion in conjunction with hydrothermolysis at near-critical conditions offers interesting features for (nearly) complete and hygienic carbon and energy recovery from human waste in a bioregenerative life support context.

Die arthroskopische Teilmenisektomie bei älteren Patienten: Erfassung der gesundheitsbezogenen Lebensqualität

AIM

Little information is available on partial arthroscopic menisectomy in patients 60 years of age or older. Due to the co-morbidity of meniscal tears and osteoarthritis in this age group, the effectiveness of this procedure is controversial. The purpose of this study was to evaluate the outcome of this procedure in terms of function and mobility in patients 60 years of age or older.

METHOD

Between 1990 and 1999, 1920 arthroscopies of the knee were performed in a single primary care institution, and 51 patients, 60 years of age or older, had a partial arthroscopic menisectomy done. Outcomes were rated using the SF-36 Health Survey and a specially designed questionnaire including items of published scores.

RESULTS

The mean age at surgery was 67 years (range: 60.3 - 78.9) and the mean follow-up was 5 years (range: 2 - 12). Due to persistent pain, 4 patients underwent a second operation including knee replacement in 3 cases and a high tibial osteotomy in 1 case. 41 patients (87.1 %) stated the arthroscopy had improved their quality of life. In terms of pain and daily life activities, the majority of the subjects showed an improvement after surgery. The SF-36 showed no clinically relevant difference compared to the control in all but one subscale.

CONCLUSION

Despite of the presence of osteoarthritis in this age group, arthroscopic partial menisectomy can improve pain, function and mobility in the mid-term course.

Anaerobic bioconversion of organic waste into biogas by hot water treatment at near-critical conditions: application in bioregenerative life support

The feasibility of nearly-complete conversion of lignocellulosic waste (70% food crops, 20% faecal matter and 10% green algae) into biogas was investigated in the context of a Life Support Project. The treatment comprised a series of processes, i.e. a mesophilic laboratory scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor and a hydrothermolysis system in near-critical water. By the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 l biogas g(-1) VSS (volatile suspended solids) added at a HRT (hydraulic retention time) of 20 d was obtained. Biogas yields further increased with 10-15% at HRT > 20 d, indicating the hydrolysis of lignocellulose to be the rate-limiting conversion step. The solids present in the CSTR-effluent were subsequently treated by hot water treatment (T approximately 310-350 degrees C, p approximately 240 bar), resulting in effective carbon liquefaction (50-60% without and 83% with carbon dioxide saturation) and complete hygienisation of the residue. Subsequent anaerobic digestion of the hydrolysate allowed further conversion of 48-60% on COD (chemical oxygen demand) basis. Thus, the total process yielded biogas corresponding with a COD conversion up to 90% of the original organic matter. It appears that mesophilic digestion in conjunction with hydrothermolysis at near-critical conditions offers interesting features for (nearly) complete, non-toxic and hygienic carbon and energy recovery from human waste in a bioregenerative life support context.

Release of bioactive transforming growth factor beta(3) from microtextured polymer surfaces in vitro and in vivo

Transforming growth factor beta(3) (TGF-beta(3)) has been under investigation with the objective of improving wound healing. Yet, little experimental knowledge exists about applications of TGF-beta(3) in implantology and tissue engineering. The aims of this study were to determine the release kinetics and bioactivity of TGF-beta(3) released from microtextured silicone and poly-L-lactic acid (PLA) surfaces in vitro and in vivo. We loaded surfaces with 100 ng of TGF-beta(3). An in vitro assay showed that TGF-beta(3) was released in a burstlike manner. Released TGF-beta(3) was capable of inhibiting the proliferation of mink lung epithelial cells, indicating that released TGF-beta(3) had remained at least partly active. Subsequently, an in vivo experiment (1 h-3 days) was performed with implants loaded with TGF-beta(3). In cryosections, TGF-beta(3) activity was assessed by an in situ bioassay. We found that active TGF-beta(3) was released for up to 24 h. Furthermore, released TGF-beta(3) could be detected up to 320 microm from the implant. On the basis of these observations, we conclude that TGF-beta(3) loaded onto microtextured polymer membranes remains functional when released in vitro and in vivo and, therefore, may represent an alternative for introducing a growth factor into a wound to achieve long-term and long-range biological effects.

Extraction of methylxanthines from guaraná seeds, maté leaves, and cocoa beans using supercritical carbon dioxide and ethanol

New experimental data on the extraction of caffeine from guaraná seeds and maté tea leaves, and theobromine from cocoa beans, with supercritical CO2 were obtained using a high-pressure extraction apparatus. The effect of the addition of ethanol to carbon dioxide on the extraction efficiency was also investigated. Caffeine extraction yields of 98% of the initial caffeine content in both wet ground guaraná seeds and maté tea leaves were obtained. Extractions of caffeine from guaraná seeds and maté tea leaves also exhibited a retrograde behavior for the two temperatures considered in this work. In the removal of theobromine from cocoa beans, a much smaller extraction yield was obtained with longer extraction periods and consequently larger solvent requirements. The results of this study confirm the higher selectivity of CO2 for caffeine in comparison with that for theobromine, and also the influence of other components in each particular natural product on the extraction of methylxanthines. The effect of the addition of ethanol to carbon dioxide on the extraction of methylxanthines was significant, particularly in the extraction of theobromine from cocoa beans. In general, the use of ethanol results in lower solvent and energy requirements and thereby improved extraction efficiency.

Effects of very long (up to 10 years) proton pump blockade on human gastric mucosa

BACKGROUND

Long-term use of proton pump inhibitors (PPI) has been reported to worsen oxyntic mucosa gastritis and the resulting gland atrophy has been considered a potential risk factor for neoplastic changes in the gastric mucosa.

AIMS

The present study examines the effect of extended continuous PPI treatment for up to 10 years on the exocrine and endocrine stomach of patients with acid-related diseases of the upper GI tract.

METHODS

Biopsies from the antral and oxyntic mucosa taken at regular time intervals were examined for gastritis, atrophy, intestinal metaplasia, Helicobacter pylori and argyrophil cells and correlated to serum gastrin levels.

RESULTS

A general amelioration of antral gastritis without relevant changes of atrophy or intestinal metaplasia, contrasted with the worsening of gastritis and gland atrophy seen in the oxyntic mucosa of reflux esophagitis (but not gastric or duodenal ulcer) patients in the presence of H. pylori infection. In association with PPI- induced hypergastrinemia, argyrophil cell hyperplasia (but not dysplasia or neoplasia) developed in the oxyntic mucosa.

CONCLUSION

The present results outline the milder pretreatment pattern and higher proneness to PPI-related, H. pylori-restricted worsening of oxyntic mucosa gastritis in reflux esophagitis compared to gastric ulcer or duodenal ulcer patients. In addition, they confirm a substantial safety of long-term PPI therapy as concerns neoplastic changes in the exocrine and endocrine human stomach.

Aborted sudden death in a patient with a structurally normal heart: the Brugada syndrome

We report a 37-year-old man with documented aborted sudden death. After resuscitation, the patient showed no structural heart disease but the ECG showed a right bundle-branch block with a descending ST segment elevation in leads V(1) and V(2). After transient normalization of the ECG, the administration of ajmaline led to spontaneous development of the distinct descending ST segment elevation in the right precordial leads and therefore to the diagnosis of Brugada syndrome. The incidence of sudden cardiac death among these patients is high. The only treatment is an implantable cardioverter-defibrillator (ICD). The Brugada syndrome should therefore be borne in mind in the differential diagnosis of sudden death.

A case of lung transplantation following Mycoplasma pneumoniae infection

Reported here is a case of severe necrotizing pneumonia following Mycoplasma pneumoniae infection that occurred in a 55-year-old man. The histological changes of lung parenchyma included granulomas and bronchiolitis obliterans. Mycoplasma infection was diagnosed by repeated antibody determination (complement fixation test) and confirmed using the polymerase chain reaction to detect the pathogen from a tracheal aspirate. Prior to this episode of pneumonia, the patient had been healthy, except for Reiter's disease that had been diagnosed 18 years previously. In addition to severe pulmonary involvement, the patient developed rhabdomyolysis with subsequent acute renal failure, Stevens-Johnson syndrome, biochemical pancreatitis, severe anemia, and an effusion of the right knee. Contrary to the symptoms of pulmonary disease, all of the extrapulmonary manifestations except anemia were transient. Due to persistent respiratory insufficiency and long-term failure to wean the patient from a respirator, a lung transplantation was performed. Five weeks after transplantation the patient died as a result of intrapulmonary hemorrhage. To the best of our knowledge, this is the first report of pneumonia due to Mycoplasma pneumoniae leading to lung transplantation. Furthermore, the multiple extrapulmonary manifestations in this case make it exceptional.