Plaster of Paris as bone substitute in spinal surgery. (9/142)

In order to assess the effectiveness of calcium sulphate (plaster of Paris; POP) as a substitute for autologous bone graft, we performed lumbar intervertebral fusion in mature sheep using POP and a variety of other graft materials, and reviewed the literature. The osteoconductivity of the POP grafts was compared to that of grafts carried out with autogenous iliac crest, frozen allogeneic bone, and ProOsteon 500 coralline bone. We also compared the osteogenicity of POP to admixtures of autogenous iliac crest bone with POP and coralline bone, and to an osteoinductive demineralized sheep bone preparation (DBM). The substrates were loaded into tubular titanium mesh, implanted into excavated disc spaces and recovered after a period of 4 months. Fusion mass segments tested in flexion and tension showed that POP was equal to autogenous bone and most other substrates. The POP fusions were significantly tougher than the DBM fusions, even though histomorphometry failed to reveal differences in the amount of trabecular bone. We conclude that POP can be used to achieve a biomechanically stable interbody lumbar vertebral fusion. In addition, our literature review indicated that POP can be used as a vehicle for local delivery of antibiotics in bone infections.  (+info)

Evidence for high activity of xylem parenchyma and ray cells in the interface of host stem and Agrobacterium tumefaciens-induced tumours of Ricinus communis. (10/142)

Rapidly developing tumours at hypocotyls of Ricinus communis, induced by Agrobacterium tumefaciens strain C58, were characterized by strong differentiation of vascular bundles and their functional connection to the host bundles. The stem/tumour interface showed increased xylem, with numerous vessels accompanied by multiseriate unlignified rays. To know how nutrients efficiently accumulate in the tumour sink tissue, cell electropotentials (E(m)) in cross-sections were mapped. The measured cells were identified by injected Lucifer Yellow. Xylem and phloem parenchyma cells and stem/tumour-located rays hyperpolarized to E(m) values of about -170 mV, which suggest high plasma membrane proton pump activities. Rapidly dividing cells of cambia or small tumour parenchyma cells had low E(m). The tumour aerenchyma and the stem cortex cells displayed values close to the energy-independent diffusion potential. The lowest values were recorded in stem pith cells. Cell K(+) concentrations largely matched the respective E(m). The pattern of individual cell electropotentials was supplemented by whole organ voltage measurements. The voltage differences between the tumour surface and the xylem perfusion solution in stems attached to the tumours, the trans-tumour electropotentials (TTP), confirm the findings of respiration-dependent and phytohormone-stimulated high plasma membrane proton pump activity in intact tumours, mainly in the xylem and phloem parenchyma and ray cells. TTPs were inhibited by addition of NaN(3), CN(-) plus SHAM or N(2) gas in the xylem perfusion solution and by external N(2) flushing. The data provide functional evidence for the structural basis of priority over the host shoot in nutrient flow from the stem to the tumour.  (+info)

Effects of amendment with ferrihydrite and gypsum on the structure and activity of methanogenic populations in rice field soil. (11/142)

Methane emission from paddy fields may be reduced by the addition of electron acceptors to stimulate microbial populations competitive to methanogens. We have studied the effects of ferrihydrite and gypsum (CaSO(4). 2H(2)O) amendment on methanogenesis and population dynamics of methanogens after flooding of Italian rice field soil slurries. Changes in methanogen community structure were followed by archaeal small subunit (SSU) ribosomal DNA (rDNA)- and rRNA-based terminal restriction fragment length polymorphism analysis and by quantitative SSU rRNA hybridization probing. Under ferrihydrite amendment, acetate was consumed efficiently (<60 microM) and a rapid but incomplete inhibition of methanogenesis occurred after 3 days. In contrast to unamended controls, the dynamics of Methanosarcina populations were largely suppressed as indicated by rDNA and rRNA analysis. However, the low acetate availability was still sufficient for activation of Methanosaeta spp., as indicated by a strong increase of SSU rRNA but not of relative rDNA frequencies. Unexpectedly, rRNA amounts of the novel rice cluster I (RC-I) methanogens increased significantly, while methanogenesis was low, which may be indicative of transient energy conservation coupled to Fe(III) reduction by these methanogens. Under gypsum addition, hydrogen was rapidly consumed to low levels ( approximately 0.4 Pa), indicating the presence of a competitive population of hydrogenotrophic sulfate-reducing bacteria (SRB). This was paralleled by a suppressed activity of the hydrogenotrophic RC-I methanogens as indicated by the lowest SSU rRNA quantities detected in all experiments. Full inhibition of methanogenesis only became apparent when acetate was depleted to nonpermissive thresholds (<5 microM) after 10 days. Apparently, a competitive, acetotrophic population of SRB was not present initially, and hence, acetotrophic methanosarcinal populations were less suppressed than under ferrihydrite amendment. In conclusion, although methane production was inhibited effectively under both mitigation regimens, different methanogenic populations were either suppressed or stimulated, which demonstrates that functionally similar disturbances of an ecosystem may result in distinct responses of the populations involved.  (+info)

Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Plaster or functional splint in gamekeepers thumb. (12/142)

A short cut review was carried out to establish whether a plaster of Paris or functional splint was better for treatment of ulnar collateral ligament rupture. Altogether 50 papers were found using the reported search, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this paper are tabulated. A clinical bottom line is stated.  (+info)

Adverse reactions to OsteoSet bone graft substitute, the incidence in a consecutive series. (13/142)

BACKGROUND: The purpose of this study was to identify factors that may be associated with the development of a sterile inflammatory reaction to OsteoSet (Wright Medical Technology) bone graft substitute. We report on a series of 58 consecutive cases of patients with benign bone lesions who developed an adverse reaction to Osteoset. All procedures were performed by a single orthopaedic oncology surgeon. METHODS: Patients who exhibited an adverse reaction to OsteoSet and those who did not were analyzed for statistical differences with respect to age, sex, volume of graft material used, size of pellet, use of alcohol washes, mixing of OsteoSet with allograft, medications, drug allergies, and smoking history. Comparisons were made between the reaction group and the non-reaction group with respect to the these variables. RESULTS: Eight definite (13.8%) and 3 probable (5.2%) reactions were identified. Symptoms developed an average of 38.9 days after the operation. There was no statistically significant difference (p>0.05) in the volume of Osteoset used, size of pellet, use of alcohol washes, mixing of OsteoSet with allograft, patient age, sex, drug allergies, or smoking history. Reported use of at least one medication was statistically significant between groups when probable reactions were included with the non-reaction group (p < 0.05), but not when probables were analyzed with the definite reaction group ( p < 0.10). A review of our patients' medication lists did not reveal any single or combination of medications likely to be responsible for this difference. Type and location of tumor also did not appear to differ significantly between the two groups. CONCLUSIONS: Although we report a 13.8%-19.0% incidence of adverse reaction to OsteoSet, we are unable to identify any statistically significant factors that might predict the development of a reaction. Fortunately, the reaction is essentially self limited and fairly benign requiring only anti-inflammatories and observation.  (+info)

The treatment of chronic osteomyelitis with a biodegradable antibiotic-impregnated implant. (14/142)

The use of local antibiotics from a biodegradable implant for chronic osteomyelitis is an attractive alternative. The implant delivers high tissue levels, obliterates dead space, aids bone repair and does not need to be removed. The purpose of this paper is to review our early clinical experience with custom-made calcium sulfate (Osteoset bone void filler) antibiotic-impregnated implants.  (+info)

Development of casting investment preventing blackening of noble metal alloys part 1. Application of developed investment for Ag-Pd-Cu-Au alloy. (15/142)

The objective of this study is to develop a casting investment that prevents the blackening of the cast surface of noble metal alloys. The experimental investments were prepared using a gypsum-bonded investment in which the metallic powders such as boron (B), silicon (Si), aluminum (Al) and titanium (Ti) were added as oxidizing agents. An Ag-Pd-Cu-Au alloy was cast into the mold made of the prepared investment. The effect of the addition of each metal powder was evaluated from the color difference between the as-cast surface and the polished surface of the cast specimen. The color of the as-cast surface approached that of the polished surface with increasing B and Al content. A lower mean value in the color difference was obtained at 0.25-1.00 mass% B content. B and Al are useful as an additive in a gypsum-bonded investment to prevent the blackening of an Ag-Pd-Cu-Au alloy. The effects of Si and Ti powder addition could not be found.  (+info)

Nitrogen and sulphur relations in effecting yield and quality of cereals and oilseed crops. (16/142)

Nitrogen and sulphur, both vital structural elements, are especially needed for the synthesis of proteins and oils. Investigations revealed the required application of sulphur is one half to one third the amount of nitrogen, and the ratio becomes narrower in mustard (Brassica juncea L.), followed by wheat and rice. The efficiency of an increased level of nitrogen required a proportionately higher amount of sulphur. A critical investigation on the effective utilization of applied vis-a-vis absorbed nitrogen in wheat and mustard envisaged accumulation of NO3-N in vegetative parts when sulphur remained proportionately low. Application of sulphur hastened the chemical reduction of absorbed NO3- for its effective utilization. The effect was more pronounced in mustard than in wheat. Easily available forms of sulphur, like ammonium sulphate and gypsum, as compared to pyrite or elemental sulphur, maintained adequate N to S ratio in rice, resulting in a reduction in the percent of unfilled grain, a major consideration in rice yield. A narrow N to S ratio, with both at higher levels, increased the oil content but raised the saponification value of the oil, a measure of free fatty acids. Whereas, a proportionately narrow N to S ratio at moderate dose resulted in adequately higher seed and oil yield with relatively low saponification value, associated with increased iodine value of the oil, indicating respectively low free fatty acids and higher proportion of unsaturated fatty acids, an index for better quality of the oil.  (+info)