Reduced efficacy of macrocyclic lactone treatments in controlling gastrointestinal nematode infections of weaner dairy calves in subtropical eastern Australia.

Faecal Egg Count Reduction Tests (FECRTs) for macrocyclic lactone (ML) and levamisole (LEV) drenches were conducted on two dairy farms in the subtropical, summer rainfall region of eastern Australia to determine if anthelmintic failure contributed to severe gastrointestinal nematode infections observed in weaner calves. Subtropical Cooperia spp. were the dominant nematodes on both farms although significant numbers of Haemonchus placei were also present on Farm 2. On Farm 1, moxidectin pour-on (MXD) drenched at 0.5 mg kg-1 liveweight (LW) reduced the overall Cooperia burden by 82% (95% confidence limits, 37-95%) at day 7 post-drench. As worm burdens increased rapidly in younger animals in the control group (n = 4), levamisole was used as a salvage drench and these calves withdrawn from the trial on animal welfare grounds after sample collection at day 7. Levamisole (LEV) dosed at 6.8 mg kg-1 LW reduced the worm burden in these calves by 100%, 7 days after drenching. On Farm 2, MXD given at 0.5 mg kg-1 LW reduced the faecal worm egg count of cooperioids at day 8 by 96% (71-99%), ivermectin oral (IVM) at 0.2 mg kg-1 LW by 1.6% (-224 to 70%) and LEV oral at 7.1 mg kg-1 LW by 100%. For H. placei the reductions were 98% (85-99.7%) for MXD, 0.7% (-226 to 70%) for IVM and 100% for LEV. This is the first report in Australia of the failure of macrocyclic lactone treatments to control subtropical Cooperia spp. and suspected failure to control H. placei in cattle.

Physio-chemical assessment of beauty leaf (Calophyllum inophyllum) as second-generation biodiesel feedstock

Recently, second-generation (non-vegetable oil) feedstocks for biodiesel production are receiving significant attention due to the cost and social effects connected with utilising food products for the production of energy products. The Beauty leaf tree (Calophyllum inophyllum) is a potential source of non-edible oil for producing second-generation biodiesel because of its suitability for production in an extensive variety of atmospheric condition, easy cultivation, high fruit production rate, and the high oil content in the seed. In this study, oil was extracted from Beauty leaf tree seeds through three different oil extraction methods. The important physical and chemical properties of these extracted Beauty leaf oils were experimentally analysed and compared with other commercially available vegetable oils. Biodiesel was produced using a two-stage esterification process combining of an acid catalysed pre-esterification process and an alkali catalysed transesterification process. Fatty acid methyl ester (FAME) profiles and important physicochemical properties were experimentally measured and estimated using equations based on the FAME analysis. The quality of Beauty leaf biodiesels was assessed and compared with commercially available biodiesels through multivariate data analysis using PROMETHEE-GAIA software. The results show that mechanical extraction using a screw press produces oil at a low cost, however, results in low oil yields compared with chemical oil extraction. High pressure and temperature in the extraction process increase oil extraction performance. On the contrary, this process increases the free fatty acid content in the oil. A clear difference was found in the physical properties of Beauty leaf oils, which eventually affected the oil to biodiesel conversion process. However, Beauty leaf oils methyl esters (biodiesel) were very consistent physicochemical properties and able to meet almost all indicators of biodiesel standards. Overall this study found that Beauty leaf is a suitable feedstock for producing second-generation biodiesel in commercial scale. Therefore, the findings of this study are expected to serve as the basis for further development of Beauty leaf as a feedstock for industrial scale second-generation biodiesel production.

Commercial application of polychaete sand filters for wastewater remediation and broodstock feeds

Summary Prototype sand-worm filtration beds were constructed at two prawn farms and one fish farm to assess and demonstrate their polychaete (marine worm) production and wastewater remediation capacities at semi-commercial scale. Wastewater treatment properties were monitored and worms produced were assessed and either sold for bait or used by the farms’ hatcheries as broodstock (prawn or fish breeder) feed. More than 34 megalitres of prawn- and fish-pond water was beneficially treated in the 116-319-d trial. The design of the polychaete-assisted sand filters (PASFs) constructed at each farm affected their water handling rates, which on average ranged from 315 to 1000 L m-2 d-1 at the three farms. A low profile design incorporating shallow bunded ponds made from polyethylene liner and timber stakes provided the easiest method of construction. This simple design applied at broad scale facilitated the highest quantities of treated water and the greatest worm production. Designs with higher sides increased the head pressure above the sand bed surface, thus increasing the amount of water that could be treated each day. Most water qualities were affected in a similar way to that demonstrated in the previous tank trials: dissolved oxygen, pH, total suspended solids and chlorophyll a levels were all consistently significantly lowered as pond water percolated through the sand bed, and dissolved forms of nitrogen and phosphorus were marginally increased on several occasions. However, unlike the previous smaller-scale tank trials, total nitrogen (TN) and total phosphorus (TP) levels were both significantly lowered by these larger-scale PASFs. The reasons for this are still unclear and require further research. Maximum TN and TP removals detected in the trial were 48.8% and 67.5%, respectively, and average removals (in unfed beds) at the three farms ranged from 20.0 to 27.7% for TN and from 22.8 to 40.8% for TP. Collectively, these results demonstrate the best suspended solids, chlorophyll and macronutrient removal capacities so far reported for any mariculture wastewater treatment methodology to date. Supplemental feeding of PASFs with fish meal was also investigated at one farm as a potential means of increasing their polychaete biomass production. Whilst fed beds produced higher biomass (152 ± 35 g m-2) compared with unfed beds (89 ± 17 g m-2) after 3.7 months of operation, the low number of replicates (2) prevented statistically significant differences from being demonstrated for either growth or survival. At harvest several months later, worm biomass production was estimated to be similar to, or in slight excess of, previously reported production levels (300-400 g m-2). Several qualities of filtered water appear to have been affected by supplemental feeding: it appeared to marginally lower dissolved oxygen and pH levels, and increased the TN and TP levels though not so much to eliminate significant beneficial water treatment effects. Periodic sampling during an artificial-tide demonstrated the tendency for treated-water quality changes during the first hour of filtration. Total nitrogen and ammonia peaked early in the tidal flow and then fell to more stable levels for the remainder of the filtration period. Other dissolved nutrients also showed signs of this sand-bed-flushing pattern, and dissolved oxygen tended to climb during the first hour and become more stable thereafter. These patterns suggest that the routine sampling of treated water undertaken at mid-inflow during the majority of the wider study would likely have overestimated the levels of TN and dissolved nutrients discharged from the beds, and hence underestimated the PASFs treatment efficacies in this regard. Analyses of polychaete biomass collected from each bed in the study revealed that the worms were free from contamination with the main prawn viruses that would create concerns for their feeding to commercial prawn broodstock in Australia. Their documented proximal and nutritional contents also provide a guide for hatchery operators when using live or frozen stock. Their dry matter content ranged from 18.3 to 22.3%, ash ranged from 10.2 to 14.0%, gross energy from 20.2 to 21.5 MJ kg-1, and fat from 5.0 to 9.2%. Their cholesterol levels ranged from 0.86 to 1.03% of dry matter, whilst total phospholipids range from 0.41 to 0.72%. Thirty-one different fatty acids were present at detectable (≥0.005% of dry matter) levels in the sampled worm biomass. Palmitic acid was by far the most prevalent fatty acid detected (1.21 ± 0.18%), followed by eicosapentaenoic (EPA) (0.48 ± 0.03%), stearic (0.46 ± 0.04%), vaccenic (0.38 ± 0.05%), adrenic (0.35 ± 0.02%), docosadienoic (0.28 ± 0.02%), arachidonic (AA) (0.22 ± 0.01%), palmitoleic (0.20 ± 0.04%) and 23 other fatty acids with average contents of less than 0.2% of dry matter. Supplemental feeding with fish meal at one farm appeared to increase the docosahexaenoic acid (DHA) content of the worms considerably, and modify the average AA : EPA : DHA from 1.0 : 2.7 : 0.3 to 1.0 : 2.0 : 1.1. Consistent with previous results, the three most heavily represented amino acids in the dry matter of sampled worms were glutamic acid (8.5 ± 0.2%), aspartic acid (5.5 ± 0.1%) and glycine (4.9 ± 0.5%). These biomass content results suggest that worms produced in PASF systems are well suited to feeding to prawn and fish broodstock, and provide further strong evidence of the potential to modify their contents for specific nutritional uses. The falling wild-fishery production of marine bloodworms in Queensland is typical of diminishing polychaete resources world-wide and demonstrates the need to develop sustainable production methods here and overseas. PASF systems offer the dual benefits of wastewater treatment for environmental management and increased productivity through a valuable secondary crop grown exclusively on waste nutrients.

Polychaete-assisted sand filters

The objective of this study was to investigate the productivity and functionality of sand filters stocked with marine worms for wastewater treatment at mariculture facilities. Medium bedding sand which is commonly available in coastal sedimentary deposits and nereidid polychaetes (Perinereis nuntia and P. helleri) from Moreton Bay in southeast Queensland were combined and studied in down-flow sand filtration beds. This combination appears to provide a new option for brackish wastewater treatment whereby the activities of the worms help to prevent sand filters from blocking with organic debris and their biomass offers a valuable by-product. Phytoplankton-rich pond waters percolating through sand-worm beds were reliably treated in several useful ways: suspended solids and chlorophyll a levels were consistently reduced by >50% by the process, and nutrients were converted into bio-available dissolved forms. Dissolved oxygen, redox and pH levels were also lowered significantly by the process. Water treatment rates of approx 1500 L m-2 d-1 were routinely achieved. P. nuntia appeared more suitable than P. helleri for stocking directly into sand filtration beds as nectochaetes, but generally exhibited slower growth. Survival and growth were influenced by stocking density. Sand-filter beds stocked with juvenile worms and fed only with eutrophic pond water demonstrated polychaete production capacities in the order of 300-400 g m-2 (eg. P. helleri: 328 g m-2 in 16 weeks). These results show how nereidid polychaetes can be reliably produced within simple, low-maintenance sand filters, and provide data necessary for the functional integration of this novel wastewater treatment system into contemporary seafood farming systems.

Polychaete-assisted sand filters – prawn farm wastewater remediation trial

Medium bedding sand which is commonly available in coastal sedimentary deposits, and a marine polychaete-worm species from Moreton Bay recently classified as Perinereis helleri (Nereididae), were deployed in a simple low-maintenance sand filter design that potentially has application at large scale. Previous work had shown that this physical and biological combination can provide a new option for saline wastewater treatment, since the worms help to prevent sand filter blocking with organic debris and offer a profitable by-product. To test the application of this new concept in a commercial environment, six 1.84 m2 Polychaete-assisted sand filters were experimentally tested for their ability to treat wastewater from a semi-intensive prawn culture pond. Polychaetes produced exclusively on the waste nutrients that collected in these gravity-driven sand filters were assessed for their production levels and nutritional contents. Water parameters studied included temperature, salinity, pH, dissolved oxygen (DO), oxidation/ reduction potential (redox), suspended solids, chlorophyll a, biological oxygen demand (BOD), and common forms of nitrogen and phosphorus. Pond water which had percolated through the sand bed had significantly lower pH, DO and redox levels compared with inflow water. Suspended solids and chlorophyll a levels were consistently more than halved by the process. Reductions in BOD appeared dependant on regular subsurface flows. Only marginal reductions in total nitrogen and phosphorus were documented, but their forms were altered in a potentially useful way: dissolved forms (ammonia and orthophosphate) were generated by the process, and this remineralisation also seemed to be accentuated by intermittent flow patterns. Flow rates of approximately 1,500 L m-2 d-1 were achieved suggesting that a 1 ha polychaete bed of this nature could similarly treat the discharge from a 10 ha semi-intensive prawn farm. Sixteen weeks after stocking sand beds with one-month-old P. helleri, over 3.6 kg of polychaete biomass (wet weight) was recovered from the trial. Production on a sand bed area basis was 328 g m-2. Similar (P>0.05) overall biomass production was found for the two stocking densities tested (2000 and 6000 m-2; n = 3), but survival was lower and more worms were graded as small (<0.6 g) when produced at the higher density (28.2 ± 1.5 % and approx. 88 %, respectively) compared with the lower density (46.8 ± 4.4 % and approx. 76 %, respectively). When considered on a weight for weight basis, about half of the worm biomass produced was generally suitable for use as bait. The nutritional contents of the worms harvested were analysed for different stocking densities and graded sizes. These factors did not significantly affect their percentages of dry matter (DM) (18.23 ± 0.57 %), ash (19.77 ± 0.80 % of DM) or gross energy 19.39 ± 0.29 MJ kg-1 DM) (n = 12). Although stocking density did not affect the worms’ nitrogen and phosphorus contents, small worms had a higher mean proportion of nitrogen and phosphorus (10.57 ± 0.17 % and 0.70 ± 0.01 % of DM, respectively) than large worms (9.99 ± 0.12 % and 0.65 ± 0.01 % of DM, respectively) (n = 6). More lipid was present in large worms grown at the medium density (11.20 ± 0.19 %) compared with the high density (9.50 ± 0.31 %) and less was generally found in small worms (7.1-7.6 % of DM). Mean cholesterol and total phospholipid levels were 5.24 ± 0.15 mg g-1 and 13.66 ± 2.15 mg g-1 DM, respectively (n = 12). Of the specific phospholipids tested, phosphatidyl-serine or sphingomyelin were below detection limits (<0.05 mg g-1), whilst mean levels of phosphatidyl-ethanolamine, phosphatidyl-inositol, phosphatidyl-choline and lysophosphatidyl-choline were 6.89 ± 1.09, 0.89 ± 0.26, 4.04 ± 1.17 and 1.84 ± 0.37 mg g-1, respectively (n = 12). Culture density generally had a more pronounced effect on phospholipid contents than did size of worms. By contrast, worm size had a more pronounced effect on total fatty acid contents, with large worms containing significantly higher (P<0.001) levels on a DM basis (46.88 ± 2.46 mg g-1) than smaller worms (27.76 ± 1.28 mg g-1). A very broad range of fatty acids were detected with palmitic acid being the most heavily represented class (up to 14.23 ± 0.49 mg g-1 DM or 27.28 ± 0.22 % of total fatty acids). Other heavily represented classes included stearic acid (7.4-8.8 %), vaccenic acid (6.8-7.8 %), arachidonic acid (3.5-4.4 %), eicosapentaenoic acid (9.9-13.8 %) and docosenoic acid (5.7-7.0 %). Stocking density did not affect (P>0.05) the levels of amino acids present in polychaete DM, but there was generally less of each amino acid tested on a weight per weight basis in large worms than in small worms. This difference was significant (P<0.05) for the most heavily represented classes being glutamic acid (73-77 mg g-1), aspartic acid (50-54 mg g-1), and glycine (46-53 mg g-1). These results demonstrate how this polychaete species can be planted and sorted at harvest according to various strategies aimed at providing biomass with specific physical and nutritional qualities for different uses.

N-Acetylglycyl-L-lysine methyl ester acetate

C llH22 N 30 + . C2H302, orthorhombic, P2~2~2~, a = 5.511(2), b = 14.588(4), c = 21.109 (4)A, Z = 4. The structure has been solved using MULTAN and refined to R = 0.079 for 993 observed reflections. The fully extended lysine side chain in the molecule is staggered between the main-chain amino and carbonyl groups. The dipeptide molecules in the crystal structure are arranged in twofold helices centred on 21 screw axes. These helices are interconnected through interactions involving the acetate and the side-chain amino groups. Each acetate group bridges two adjacent side-chain amino groups, related by an a translation, giving rise to an infinitely long chain of alternating negatively charged carboxylate and positively charged amino groups.

Nutritional status of a nereidid polychaete cultured in sand filters of mariculture wastewater

This study examined the nutritional composition of the intertidal marine polychaete Perinereis helleri (Nereididae)when artificially cultured in sand filters treating mariculture wastewater. Moisture levels in harvested P. helleri ranged from 758 to 855 g kg1, and ash, from 23 to 61 g kg1 wet matter (WM). Stocking density and graded size after harvest significantly affected their composition. Higher total lipid contents were found in large (>0.6 g) P. helleri(16–19 g kg1 WM) and those grown at the lowest density(1000 m2: 18 g kg 1 WM) than in small (≤0.6 g) ones (14 g kg1 WM) and those grown at the highest densities (4000–6000 m2: 13–16 g kg1 WM). Several fatty acids within a very broad profile (some 30 identified) reflected this pattern, yet their ARA/EPA/DHA ratios were relatively unaffected. Feeding the polychaete-assisted sand filters (PASF) with fish meal to increase worm biomass productivity significantly increased their DHA content. Other components (e.g. protein, phospholipids, cholesterol, carbohydrate, amino acids, nitrogen, minerals and bromophenols) and nutritional factors (e.g. maturity, feeding seaweed and endemic shrimp viral content) were also investigated. Results suggest that PASF-produced P. helleri have a well-balanced nutritional profile for penaeid shrimp and fish broodstock.

Stretching single DNA-molecules with temperature-stabilized optical tweezers

This thesis consists of two parts; in the first part we performed a single-molecule force extension measurement with 10kb long DNA-molecules from phage-λ to validate the calibration and single-molecule capability of our optical tweezers instrument. Fitting the worm-like chain interpolation formula to the data revealed that ca. 71% of the DNA tethers featured a contour length within ±15% of the expected value (3.38 µm). Only 25% of the found DNA had a persistence length between 30 and 60 nm. The correct value should be within 40 to 60 nm. In the second part we designed and built a precise temperature controller to remove thermal fluctuations that cause drifting of the optical trap. The controller uses feed-forward and PID (proportional-integral-derivative) feedback to achieve 1.58 mK precision and 0.3 K absolute accuracy. During a 5 min test run it reduced drifting of the trap from 1.4 nm/min in open-loop to 0.6 nm/min in closed-loop.

Methods to determine resistance to anthelmintics when continuing larval development occurs

The in vivo faecal egg count reduction test (FECRT) is the most commonly used test to detect anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) of ruminants in pasture based systems. However, there are several variations on the method, some more appropriate than others in specific circumstances. While in some cases labour and time can be saved by just collecting post-drench faecal worm egg counts (FEC) of treatment groups with controls, or pre- and post-drench FEC of a treatment group with no controls, there are circumstances when pre- and post-drench FEC of an untreated control group as well as from the treatment groups are necessary. Computer simulation techniques were used to determine the most appropriate of several methods for calculating AR when there is continuing larval development during the testing period, as often occurs when anthelmintic treatments against genera of GIN with high biotic potential or high re-infection rates, such as Haemonchus contortus of sheep and Cooperia punctata of cattle, are less than 100% efficacious. Three field FECRT experimental designs were investigated: (I) post-drench FEC of treatment and controls groups, (II) pre- and post-drench FEC of a treatment group only and (III) pre- and post-drench FEC of treatment and control groups. To investigate the performance of methods of indicating AR for each of these designs, simulated animal FEC were generated from negative binominal distributions with subsequent sampling from the binomial distributions to account for drench effect, with varying parameters for worm burden, larval development and drench resistance. Calculations of percent reductions and confidence limits were based on those of the Standing Committee for Agriculture (SCA) guidelines. For the two field methods with pre-drench FEC, confidence limits were also determined from cumulative inverse Beta distributions of FEC, for eggs per gram (epg) and the number of eggs counted at detection levels of 50 and 25. Two rules for determining AR: (1) %reduction (%R) < 95% and lower confidence limit <90%; and (2) upper confidence limit <95%, were also assessed. For each combination of worm burden, larval development and drench resistance parameters, 1000 simulations were run to determine the number of times the theoretical percent reduction fell within the estimated confidence limits and the number of times resistance would have been declared. When continuing larval development occurs during the testing period of the FECRT, the simulations showed AR should be calculated from pre- and post-drench worm egg counts of an untreated control group as well as from the treatment group. If the widely used resistance rule 1 is used to assess resistance, rule 2 should also be applied, especially when %R is in the range 90 to 95% and resistance is suspected.

Anthelmintic resistance in ovine gastrointestinal nematodes in inland southern Queensland

Objective To establish the prevalence of anthelmintic resistance in ovine gastrointestinal nematodes in southern Queensland. Design An observational parasitological study using the faecal egg count reduction test. Methods Sheep farms (n = 20) enrolled in this study met the twin criteria of using worm testing for drench decisions and having concerns about anthelmintic efficacy. On each farm, 105 sheep were randomly allocated to one of six treatment groups or an untreated control group. Faecal samples were collected on day 0 and days 10–14 for worm egg counts and larval differentiation. Single- and multi-combination anthelmintics, persistent and non-persistent, oral liquid or capsule, pour-on and injectable formulations were tested. Monepantel was not tested. Farmers also responded to a questionnaire on drenching practices. Results Haemonchus contortus was the predominant species. Efficacy <95% was recorded on 85% of farms for one or more anthelmintics and on 10% of farms for six anthelmintics. No resistance was identified on three farms. The 4-way combination product was efficacious (n = 4 farms). Napthalophos resistance was detected on one farm only. Resistance to levamisole (42% of farms), moxidectin injection (50% of farms) and the closantel/abamectin combination (67% of farms) was identified. Moxidectin oral was efficacious against Trichostrongylus colubriformis, which was predominant on only one farm. Of the farms tested, 55% ran meat breeds, 60% dosed more than the recommended dose rate and 70% always, mostly or when possible practised a ‘drench and move’ strategy. Conclusion This level of anthelmintic resistance in southern Queensland will severely compromise worm control and force increased use of monepantel.

N-Acetylglycyl-L-lysine methyl ester acetate

C llH22 N 30 + . C2H302, orthorhombic, P2~2~2~, a = 5.511(2), b = 14.588(4), c = 21.109 (4)A, Z = 4. The structure has been solved using MULTAN and refined to R = 0.079 for 993 observed reflections. The fully extended lysine side chain in the molecule is staggered between the main-chain amino and carbonyl groups. The dipeptide molecules in the crystal structure are arranged in twofold helices centred on 21 screw axes. These helices are interconnected through interactions involving the acetate and the side-chain amino groups. Each acetate group bridges two adjacent side-chain amino groups, related by an a translation, giving rise to an infinitely long chain of alternating negatively charged carboxylate and positively charged amino groups.

Regulation of Growth by Drosophila FoxO Transcription Factor

Forkhead box class O (FoxO) transcription factors are members of the forkhead box transcription factor superfamily, with orthologues in various species such as human, worm and fly. FoxO proteins are key regulators of growth, metabolism, stress resistance and, consequently, life span. FoxOs integrate signals from different pathways, e.g. the growth controlling Insulin-TOR signaling pathway and the stress induced JNK and Hippo signaling pathways. FoxO proteins have evolved to guide the cellular response to varying energy and stress conditions by inducing the expression of genes involved in the regulation of growth and metabolism. This work has aimed to deepen the understanding of how FoxO executes its biological functions. A particular emphasis has been laid to its role in growth control. Specifically, evidence is presented indicating that FoxO restricts tissue growth in a situation when TOR signaling is high. This finding can have implications in a human condition called Tuberous sclerosis, manifested by multiple benign tumors. Further, it is shown that FoxO directly binds to the promoter and regulates the expression of a Drosophila Adenylate cyclase gene, ac76e, which in turn modulates the fly s development and growth systemically. These results strengthen FoxOs position among central size regulators as it is able to operate at the level of individual cells as well as in the whole organism. Finally, an attempt to reveal the regulatory network upstream of FoxO has been carried out. Several putative FoxO activity regulators were identified in an RNAi screen of Drosophila kinases and phosphatases. The results underscore that FoxO is regulated through an elaborate network, ensuring the correct execution of key cellular processes in metabolism and response to stress. Overall, the evidence provided in this study strengthens our view of FoxO as a key integrator of growth and stress signals.

The effects of low-intensity ultrasound in bioabsorbable self-reinforced poly-L-lactide -fixed cancellous bone fracture

The purpose of the present study was to investigate the effects of low-intensity ultrasound on bioabsorbable self-reinforced poly-L-lactide (SR-PLLA) screws and on fracture healing after SR-PLLA device fixation in experimental and clinical cancellous bone fracture. In the first experimental study, the assessment of the mechanical strengths of the SR-PLLA screws was performed after 12 weeks of daily 20-minute ultrasound exposure in vitro. In the second experimental study, 32 male Wistar rats with an experimental distal femur osteotomy fixed with an SR-PLLA rod were exposed for daily low-intensity ultrasound treatment for 21 days. The effects on the healing bone were assessed. The clinical studies consist of three prospective, randomized, and placebo-controlled series of dislocated lateral malleolar fractures fixed with one SR-PLLA screw. The total number of the patients in these series was 52. Half of the patients were provided randomly with a sham ultrasound device. The patients underwent ultrasound therapy 20 minutes daily for six weeks. Radiological bone healing was assessed both by radiographs at two, six, nine, and 12 weeks and by multidetector computed tomography (MDCT) scans at two weeks, nine weeks, and 18 months. Bone mineral density was assessed by dual-energy X-ray absorptiometry (DXA). The clinical outcome was assessed by both Olerud-Molander scoring and clinical examination of the ankle. Low-intensity ultrasound had no effects on the mechanical properties and degradation behaviour of the SR-PLLA screws in vitro. There were no obvious signs of low-intensity ultrasound-induced enhancement in the bone healing in SR-PLLA-rod-fixed metaphyseal distal femur osteotomy in rats. The biocompatibility of low-intensity ultrasound treatment and SR-PLLA was found to be good. In the clinical series low-intensity ultrasound was observed to have no obvious effects on the bone mineral density of the fractured lateral malleolus. There were no obvious differences in the radiological bone healing times of the SR-PLLA-screw-fixed lateral malleolar fractures after low-intensity ultrasound treatment. Low-intensity ultrasound did not have any effects on radiological bone morphology, bone mineral density or clinical outcome 18 months after the injury. There were no obvious findings in the present study to support the hypothesis that low-intensity pulsed ultrasound enhances bone healing in SR-PLLA-rod-fixed experimental metaphyseal distal femur osteotomy in rats or in clinical SR-PLLA-screw-fixed lateral malleolar fractures. It is important to limit the conclusions of the present set of studies only to lateral malleolar fractures fixed with an SR-PLLA screw.

Anterior cruciate ligament reconstruction with special reference to magnetic resonance imaging of the postoperative outcome

Anterior cruciate ligament (ACL) tear is a common sports injury of the knee. Arthroscopic reconstruction using autogenous graft material is widely used for patients with ACL instability. The grafts most commonly used are the patellar and the hamstring tendons, by various fixation techniques. Although clinical evaluation and conventional radiography are routinely used in follow-up after ACL surgery, magnetic resonance imaging (MRI) plays an important role in the diagnosis of complications after ACL surgery. The aim of this thesis was to study the clinical outcome of patellar and hamstring tendon ACL reconstruction techniques. In addition, the postoperative appearance of the ACL graft was evaluated using several MRI sequences. Of the 175 patients who underwent an arthroscopically assisted ACL reconstruction, 99 patients were randomized into patellar tendon (n=51) or hamstring tendon (n=48) groups. In addition, 62 patients with hamstring graft ACL reconstruction were randomized into either cross-pin (n=31) or interference screw (n=31) fixation groups. Follow-up evaluation determined knee laxity, isokinetic muscle performance and several knee scores. Lateral and anteroposterior view radiographs were obtained. Several MRI sequences were obtained with a 1.5-T imager. The appearance and enhancement pattern of the graft and periligamentous tissue, and the location of bone tunnels were evaluated. After MRI, arthroscopy was performed on 14 symptomatic knees. The results revealed no significant differences in the 2-year outcome between the groups. In the hamstring tendon group, the average femoral and tibial bone tunnel diameter increased during 2 years follow-up by 33% and 23%, respectively. In the asymptomatic knees, the graft showed homogeneous and low signal intensity with periligamentous streaks of intermediate signal intensity on T2-weighted MR images. In the symptomatic knees, arthroscopy revealed 12 abnormal grafts and two meniscal tears, each with an intact graft. Among 3 lax grafts visible on arthroscopy, MRI showed an intact graft and improper bone tunnel placement. For diagnosing graft failure, all MRI findings combined gave a specificity of 90% and a sensitivity of 81%. In conclusion, all techniques appeared to improve patients' performance, and were therefore considered as good choices for ACL reconstruction. In follow-up, MRI permits direct evaluation of the ACL graft, the bone tunnels, and additional disorders of the knee. Bone tunnel enlargement and periligamentous tissue showing contrast enhancement were non-specific MRI findings that did not signify ACL deficiency. With an intact graft and optimal femoral bone tunnel placement, graft deficiency is unlikely, and the MRI examination should be carefully scrutinized for possible other causes for the patients symptoms.

A low temperature Weissenberg camera

Details of the design and operation of a Weissenberg camera suitable for x-ray investigations between -180°c and 200°c are presented. The camera employs a novel arrangement of spur and bevel gears to couple the goniometer spindle to the worm rod which controls the range of oscillation. The entire drive system and the goniometer assembly are mounted on a support which permits the insertion or removal of a cylindrical cassette from the gear-box side without disturbing the cooling assembly and the layer-line screen. The cassette can also be inserted from the opposite side. The specimen can be cooled either directly by a stream of liquid air or by the cold gas from its evaporation. Condensation of moisture at low temperatures is prevented by heating the layer-line tubes internally.