Characterization and alkaline pretreatment of rice husk varieties in Uganda for potential utilization as precursors in the production of activated carbon and other value-added products.

In this study, 13 rice husk (RH) varieties from 4 agro-ecological zones in Uganda were characterized, NaOH-pretreated, and evaluated for their potential utilization as precursors for production of bio-oil, ash, char, and activated carbon for selected applications. RH varieties were characterized through particle size analysis, bulk density, proximate and ultimate analyses, specific surface area, pore volume, as well as lignocellulosic and inorganic compositions. Selected RH varieties were subsequently pretreated at NaOH concentrations of 1-4%w/v, using pretreatment ratios of 5 g RH: 40 mL NaOH. Properties varied among RH varieties, suiting them as feedstocks for different applications. Upland rice husk varieties are more suited precursors for production of bio-oil, and activated carbon due to their relatively lower ash content, higher specific surface area, as well as higher volatile matter and fixed carbon contents. Upland rice husks could as well be employed in the preparation of electrodes for electrochemical devices, due to their relatively higher specific surface area. A high ash content (21-32% dry basis) of lowland rice husks presents good prospects for their calcination, since larger amounts of rice husk ash could be obtained, and employed in different applications. Lowland rice husk varieties could also be more suited precursors for production of char for soil amendment, due to their relatively higher ash content, which subsequently increases their char yields. However, alkaline pretreatment of rice husks using 2-4%w/v NaOH can reduce the ash content by as much as 74-93%, depending on the rice husk variety, which paves way for utilizing rice husks with a high ash content in different applications. Aside from ash reduction, the enhanced specific surface area (1.2-1.7 m2 g-1), volatile matter (68-79%db) and fixed carbon (19-24%db) contents of NaOH-pretreated rice husks suggests they are more suited feedstocks than when employed in their raw form, for production of bio-oil, as well as activated carbon.

The influence of cancellous bone density on load sharing in human lumbar spine: a comparison between an intact and a surgically altered motion segment.

The aim of the current study is twofold: first, to compare load sharing in compression between an intact and a surgically repaired lumbar spine motion segment L3/4 using a biomechanically validated finite element approach; second, to analyse the influence of bone mineral density on load sharing. Six cadaveric human lumbar spine segments (three segments L2/3 and three segments L4/5) were taken from fresh human cadavers. The intact segments were tested under axial compression of 600 N, first without preload and then following instrumented stabilisation. These results were compared to a finite element model simulating the effect of identical force on the intact segments and the segments with constructs. The predictions of both the intact and the surgically altered finite element model were always within one standard deviation of the mean stiffness as analysed by the biomechanical study. Thus, the finite element model was used to analyse load sharing under compression in an intact and a surgically repaired human lumbar spine segment model, using a variety of E moduli for cancellous bone of the vertebral bodies. In both the intact and the surgically altered model, 89% of the applied load passed through the vertebral bodies and the disc if an E modulus of 25 MPa was used for cancellous bone density. Using 10 MPa--representing soft, osteoporotic bone--this percentage decreased, but it increased using 100 MPa in both the intact and the altered segment. Thus, it is concluded that reconstruction of both the disc and the posterior elements with the implants used in the study recreates the ability of the spine to act as a load-sharing construction in compression. The similarity in load sharing between normal and instrumented spines appears to depend on assumed bone density, and it may also depend on applied load and loading history.

[Effect of spongiosa density on load bearing of the lumbar spine.A finite element analysis]. / Der Einfluss der Spongiosadichte auf das Load-Sharing der Lendenwirbelsäule. Eine Finite-Elemente-Analyse.

OBJECTIVE: Different parts of the human spine have to accomplish different functions. But little is known about the exact distribution of forces within the spine and whether this is influenced by bone quality. The purpose of this study was to predict fields and extent of greatest load in compression in a human lumbar spine motion segment using a finite element model. METHODS: A three dimensional isotrophic finite element model was generated using the software ANSYS 5.4. Spinal loading was performed in axial compression (600 N). The model was validated by biomechanical analysis using 12 human spinal segments that were loaded with the same forces. Prediction was done with different E-modulus for cancellous bone, representing a wide range of bone quality between osteoporotic and strong bone quality. RESULTS: Load-sharing was influenced by bone quality: the weaker bone quality is, the higher is the extent of load that is passed through the posterior part of the spine. CONCLUSION: This finite element model predicts that load-sharing in a lumbar spine segment with decreased bone mineral density is different from that in healthy segments. A decrease of bone mineral density is resulting in an increase of load that is passed through the posterior part of the lumbar spine. Keeping in mind the simplifications of this model, the results may influence surgical treatment of patients suffering from osteoporosis or osteolytic destructions of the lumbar spine.

[Initial stability of two PLIF-techniques. A biomechanical comparison using a finite element model]. / Die Primärstabilität von zwei Plif-Techniken.Ein biomechanischer Vergleich mit der Finite-Elemente-Methode.

The purpose of this study was to compare the initial stiffness of two techniques for posterior interbody lumbar fusion (PLIF) by a finite element approach. Thus a finite element model of a human L3/4 spinal segment was generated. Stiffness of the intact model was tested under compression (600 N), torsion (25 Nm) and shearing forces (250 N) without preload. The results were compared to the stiffness following simulation of PLIF with two BAK-Cages and PLIF with two Harms-Cages and additional posterior screw-rod-osteosynthesis. PLIF with two BAK-Cages resulted in a loss of stiffness in compression, torsion and shearing. PLIF with two Harms-Cages and posterior osteosynthesis resulted in an increase of stiffness in compression, torsion and shearing.

[Is the prediction of initial stability of cervical spinal osteo-synthesis possible using a finite element model?]. / Ist die Beurteilung der Primärstabilität zervikaler Osteosynthesen durch ein Finite-Elemente Modell möglich?

The study is dealing with a three segmental (C4-C7) finite element model of the intact human cervical spine. Additionally, anterior cervical fusion and plating (ACFP) with Caspar-plate and bicortical screws in C5/6 was simulated. The models were loaded using pure moments of 2.5 Nm in flexion-extension, axial rotation and lateral bending. The range of motion in C5/6 was calculated and compared to the results of a biomechanical in vitro study, that used six cadaveric human spinal segments C4-C7 for analysing range of motion C5/6 in the intact state and following ACFP. The predictions of the finite element models were always within one standard deviation of the results of the in vitro study. Thus, the current model could be used for first analysis on new C-spine implants. However, the results should be interpreted as a trend and the limitations of these models should be kept in mind.

Motion of threaded cages in posterior lumbar interbody fusion.

A high rate of pseudarthrosis and a high overall rate of implant migration requiring surgical revision has been reported following posterior lumbar interbody fusion using BAK threaded cages. The high rate of both pseudarthrosis and implant migration may be due to poor fixation of the implant. The purpose of this study was to analyse the motion of threaded cages in posterior lumbar interbody fusion. Six cadaveric human lumbar spine segments (three L2/3 and three L4/5 segments) were prepared for biomechanical testing. The segments were tested, without preload, under forces of axial compression (600 N), torsion (25 Nm) and shearing force (250 N). The tests were performed first with the segments in an intact state, and subsequently following instrumented stabilisation with two BAK cages via a posterior approach. These results were compared with those of a finite element model simulating the effects of identical forces on the segments with constructs. As the results were comparable, the finite element model was used for analysing the motion of BAK cages within the disc space. Motion of the implants was not seen in compression. In torsion, a rolling motion was noted, with a range of motion of 10.6 degrees around the central axis of the implant when left/right torsion (25 Nm) was applied. The way the implants move within the segment may be due to their special shape: the thread of the implants can not prevent the BAK cages rolling within the disc space.

[Primary stability of 2 PLIF (posterior lumbar interbody fusion)--a biomechanical in vitro comparison]. / Die Primärstabilität zweier PLIF-Techniken--Ein biomechanischer In-vitro-Vergleich.

OBJECTIVE: The purpose of this biomechanical in-vitro-study was to compare two different PLIF-techniques with two types of implants on human lumbar spine: PLIF with threaded cages, (Bagby and Kuslich, Spinetech, Minneapolis, USA) and PLIF with the Moss-Miami-implants, (DePuy International Limited, Leeds, Great Britain). METHODS: Six cadaveric human lumbar spine segments L2-5 were explanted, frozen at -20 degrees C and thawed before preparation. They were cut in two parts by discectomie and arthrotomie L3/4, so six specimen L2/3 and six specimen L4/5 were obtained and used in a crossover-trial. Analysis included testing in a tension-torsion-machine under axial compression with 600 N, rotation (left-right) with 25 Nm and shearing forces with 250 N without preload. This was first done in the intact and then in the fused specimen. RESULTS: Stiffness before treatment was comparable in both groups irrespective of location. Posttreatment stiffness was higher with MOSS-MIAMI-implants as compared to PLIF with BAK-cages. Average relative superiority (and 95%-confidence intervall) were 1.98 (1.01-3.69) for compression, 2.30 (0.85-6.24) for rotation and 1.73 (0.78-3.84) for shearing. Statistical comparison of log posttreatment stiffness was significant for compression but not for rotation and shearing (2-sided independent crossover t-test). CONCLUSION: This biomechanical in-vitro-study demonstrates the higher initial stability of PLIF with titanium surgical mesh and posterior instrumentation when compared to PLIF with threaded cages alone.

[Primary stability of 2 PLIF (posterior lumbar interbody fusion) techniques--a biomechanical and finite element analysis]. / Die Primärstabilität von zwei PLIF-Techniken--Eine biomechanische und Finite Elemente Analyse.

The purpose of this study was to compare the initial stiffness of two techniques for posterior interbody lumbar fusion by biomechanical and finite element analysis. Initial stiffness was tested under compression, torsion and shearing forces. The effect of an increasing initial stability by additional posterior instrumentation is proven by the biomechanical analysis and the finite element method.

GAS TRANSPORT IN THE HAEMOLYMPH OF ARACHNIDS - OXYGEN TRANSPORT AND THE PHYSIOLOGICAL ROLE OF HAEMOCYANIN

Oxygen equilibrium curves and the relationships between the partial pressure of CO2 and pH were determined for the haemolymph of the arachnids Eurypelma californicum, Pandinus imperator and Cupiennius salei. A new type of experimental apparatus was constructed, tested and used to make these measurements on small undiluted cell-free haemolymph samples. Most of its components were made in our workshop and were inexpensive. The apparatus proved to be very reliable as demonstrated by control (oxygen concentration) experiments. In previous reports on O2 equilibrium curves of E. californicum haemocyanin, Tris­HCl buffer was used to set the pH, whereas in our experiments, pH was adjusted by altering the partial pressure of CO2. The O2 concentration measurements demonstrate an increase in oxygen affinity of E. californicum haemocyanin when using Tris­HCl buffer. The position and shape of the O2 equilibrium curves of E. californicum and P. imperator haemocyanin show a distinct dependency on pH. Oxygen affinity is lower in E. californicum and cooperativity changes with pH in E. californicum, but not in P. imperator. Oxygen transport in the haemolymph of E. californicum during rest, activity and recovery was calculated on the basis of the O2 equilibrium curves of undiluted haemolymph. Apart from oxygen transport, there are indications that haemocyanin is also involved in other physiological processes. For example, it may function as a storage protein.

GAS TRANSPORT IN THE HAEMOLYMPH OF ARACHNIDS - CARBON DIOXIDE TRANSPORT AND ACID-BASE BALANCE

The relationships between PCO2 and pH were determined in cell-free undiluted haemolymph of the arachnids Eurypelma californicum, Pandinus imperator and Cupiennius salei. The pH/bicarbonate diagrams and the CO2 equilibrium curves were calculated, using the Henderson­Hasselbalch equation, for haemolymph sampled at rest and during recovery from exercise. The calculations of solubility (alphaCO2) and dissociation constant (pK"') were based on additional ion concentration measurements. Blood gas analyses corroborate these results: after locomotor activity, there is a metabolic acidosis linked to the accumulation of lactate in the haemolymph. The concentration of bicarbonate in the haemolymph of resting individuals is quite different in the three species and is related to the extent of post-exercise bicarbonate depletion. During early recovery, buffering in the haemolymph strongly depends upon CO2 release. Potassium and magnesium concentrations in the haemolymph increase after exercise. During cold-acclimation (to 10 °C), there is a metabolic acidosis in the tarantula's haemolymph that is linked to the accumulation of acetate.

Hemocyanins in spiders, XXIII. Complete amino-acid sequence of subunit a of Eurypelma californicum hemocyanin.

The complete amino-acid sequence of subunit a of the hemocyanin of the tarantula Eurypelma californicum was determined by manual sequencing. By limited chymotrypsinolysis, subunit a is split into two fragments of 25 kDa and 40 kDa, respectively, only one single peptide bond being attacked. The whole chain contains 15 methionine residues, after cyanogen bromide cleavage, 15 peptides were identified indicating that one residue (Met85) was not split by the cyanogen bromide reaction. For subcleavages, trypsin, chymotrypsin, Staphylococcus aureus proteinase, and Astacus fluviatilis proteinase were employed. The total chain length comprises 627 amino-acid residues, carbohydrate side chains were not found.

Clinical, biochemical and immunological effectiveness of diacetyl-splenopentin (BCH 069) in hay fever.

Diacetyl-splenopentin (BCH 069) is a new pentapeptide of splenin modified by twofold acetylation. BCH 069 has thymopentin-like activity demonstrated by in vivo animal and in vitro human studies. Two groups of patients received 50 mg BCH 069 and placebo, respectively, by subcutaneous injection 3 times weekly for 4 weeks. The third group of patients received 50 mg BCH 069 by intravenous injection 3 times weekly for 6 weeks. The therapy was carried out during the peak of the pollen season. BCH 069 intravenous treatment was found to be significantly superior to placebo treatment in reducing clinical symptoms. Biochemical inflammatory signs were not observed. No increase of bronchomotoric reactivity was established in comparison to the placebo group. There was a significantly lower increase in gras-spollen specific IgE and IgG4 in the intravenous group of BCH 069. Subcutaneous therapy with BCH 069 was not effective. The study demonstrated that BCH 069 used intravenously induces clinical improvement in patients suffering from hay fever. Thus the possibility to influence hyperreactive conditions of the immune system has been confirmed. The study indicates that various application routes of BCH 069 have different effects on the immune system.

[Disease-specific and non-specific seasonal parameter changes in hayfever patients]. / Krankheitsspezifische und -unspezifische saisonale Parameterveränderungen bei Pollinosepatienten.

10 patients have been treated by subcutaneous injections of placebo three times weekly for 4 weeks within a phase-I trial of BCH-069. Immunological, hematological and biochemical parameters were observed at different times: preseasonal, seasonal and postseasonal. --Some new observations are reported, which are induced by the seasonal inflammation. For example there was a strong increase of C-reactive protein and also an increase in the triglyceride level. --The parameters could be useful for trials of new antiallergic drugs in hay fever in the future.

[Age-dependent sensitivity of human lymphocytes to the immunomodulating effect of bovine and human diacetyl splenopentin]. / Altersabhängige Sensitivität humaner Lymphozyten gegen die immunmodulatorische Wirkung von bovinem und humanem Diacetyl-Splenopentin.

Both newborns and elderly adults suffer from physiological immunodeficiency. The molecular mechanisms responsible for this immunodeficiency are currently investigated by many laboratories. The aim of our investigations was to answer the question wether these immunodeficiencies could be influenced by bovine and/or human diacetyl-splenopentin, two newly developed immunostimulatory peptides. The in vitro effects of these peptides were studied using the lymphocyte transformation test and the detection of the immunoglobulin production (IgG, IgM) by lymphocytes. Thymopentin was used as standard for these investigations. The age dependence of lymphocyte sensitivity was estimated using cells of the following groups of blood donors: newborns (cord blood); young donors (20-30 yr); old donors (over 70 yr). All peptides were shown to have the same effects. The stimulated lymphocyte proliferation (PHA, anti-CD3) was inhibited in young donors and further increased in old donors. There was no influence in the case of newborns. The biological activity of human diacetyl-splenopentin was shown to be higher in comparison with bovine diacetyl-splenopentin.

[Status and developmental trends in the use of fluorescence microscopy studies in microbiology]. / Stand und Entwicklungstendenzen der Anwendung fluoreszenzmikroskopischer Untersuchungen in der Mikrobiologie.

There are many applications for fluorescence microscopy in the field of microbiology for diagnostic and scientific purposes. Autofluorescence as well as secondary fluorescence induced by staining of specimen with fluorochromes or with fluorochrome labeled antibodies are used for detection and differentiation of microorganisms. Small demands for object preparation and short test times are advantages for screening tests. During the last time considerable progresses in methods and technical equipments are noticeable and offer numerous new applications for fluorescence microscopy. New microscopes show clearly increased intensity of excitation. This requires a selection of object slides and cover glasses with lowest autofluorescence, blocking of fading by addition of PPD to embedding medium and a better adaptation of filters for excitation and fluorescence to the characteristics of fluorochromes. Multiple fluorochroming and combined application of fluorescence and alternative contrast techniques such as phase contrast are of rising importance in practice.

Double staining technique using a combination of indirect and direct immunofluorescence with monoclonal antibodies.

A simple method for double staining by immunofluorescence is described. If for double staining using monoclonal antibodies of the same species only one antibody is conjugated with FITC or TRITC, a combination of indirect and direct immunofluorescence is possible. For cell staining the following incubation steps are carried out: Monoclonal antibody I (unlabelled, mouse), anti-mouse immunoglobulin serum FITC- or TRITC-conjugated, normal mouse serum for blocking of free binding sites of the anti-mouse immunoglobulin, and monoclonal antibody II (mouse) which is conjugated with an alternative fluorochrome. The use of this method is demonstrated for investigation of single cell suspensions (performed as a slide test) and of cryostat sections.

Photomicrography of weakly fluorescent objects--employment of p-phenylene diamine as a blocker of fading.

By adding p-phenylene diamine (PPD) to the embedding medium, the fading of fluorescent objects labeled with FITC or mithramycin is substantially reduced. Thus, a multiple quantity of light, as compared to without additive, may be obtained from the objects and so photomicrography be improved or made possible at all. For microfluorometry as well as for subjective fluorescence microscopy the employment of PPD is not very helpful.

[Subacute idiopathic polymyositis with rare antiribosomal antibodies in the serum - clinical course during immunosuppressive long-term therapy]. / Subakute idiopathische Polymyositis mit seltenen antiribosomalen Antikörpern im Serum - Klinischer Verlauf unter immunsuppressiver Langzeittherapie.

In a 66-year-old woman a polymyositis with subacute course was observed. The proof of very rare antiribosomal antibodies with a high titre on the serum was remarkable. Only after a cytostatic immunosuppressive therapy a clinical improvement developed, parallel to which there was a tendency to normalisation of immunological and enzyme-pathological parameters. The decrease of the titres of the autoantibodies is evaluated as indicators of the effectivity of the medicamentous immunosuppression and using the special literature is discussed in its importance also concerning the possibilites of the control of the clinical course.