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Background: Experimental knee implant wear testing according to ISO 14243 is a standard procedure, but it inherently possesses limitations for preclinical evaluations due to extended testing periods and costly infrastructure. In an effort to overcome these limitations, we hereby develop and experimentally validate a finite-element (FE)-based algorithm, including a novel cross-shear and contact pressure dependent wear and creep model, and apply it towards understanding the sensitivity of wear outcomes to the applied boundary conditions., Methods: Specifically, we investigated the application of in vivo data for level walking from the publicly available "Stan" data set, which contains single representative tibiofemoral loads and kinematics derived from in vivo measurements of six subjects, and compared wear outcomes against those obtained using the ISO standard boundary conditions. To provide validation of the numerical models, this comparison was reproduced experimentally on a six-station knee wear simulator over 5 million cycles, testing the same implant Stan's data was obtained from., Results: Experimental implementation of Stan's boundary conditions in displacement control resulted in approximately three times higher wear rates (4.4 vs. 1.6 mm 3 per million cycles) and a more anterior wear pattern compared to the ISO standard in force control. While a force-controlled ISO FE model was unable to reproduce the bench test kinematics, and thus wear rate, due to a necessarily simplified representation of the simulator machine, similar but displacement-controlled FE models accurately predicted the laboratory wear tests for both ISO and Stan boundary conditions. The credibility of the in silico wear and creep model was further established per the ASME V&V-40 standard., Conclusions: The FE wear model is suitable for supporting future patient-specific models and development of novel implant designs. Incorporating the Stan data set alongside ISO boundary conditions emphasized the value of using measured kinematics in displacement control for reliably replicating in vivo joint mechanics in wear simulation. Future work should focus on expanding the range of daily activities simulated and addressing model sensitivity to contact mechanics to further enhance predictive accuracy., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: MJD, SHHN, BW, and WRT declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. PF and FA are employed at Zimmer Biomet, the company producing the Innex implant investigated here., (© 2024. The Author(s).)

Despite availability of in vivo knee loads and kinematics data, conventional load- and displacement-controlled configurations still can't accurately predict tibiofemoral loads from kinematics or vice versa. We propose a combined load- and displacement-control method for joint-level simulations of the knee to reliably reproduce in vivo contact mechanics. Prediction errors of the new approach were compared to those of conventional purely load- or displacement-controlled models using in vivo implant loads and kinematics for multiple subjects and activities (CAMS-Knee dataset). Our method reproduced both loads and kinematics more closely than conventional models and thus demonstrates clear advantages for investigating tibiofemoral contact or wear.

Analysis of polyethylene (PE) wear in knee implants is crucial for understanding the factors leading to revision in total knee arthroplasty. Importantly, current experimental and computational methods for predicting insert wear can only be validated against true in vivo measurements from retrievals. This study quantitatively investigated in vivo PE wear rates in fixed-bearing (FB) (n = 21) and rotating-platform (n = 53) implant retrievals. 3D surface geometry of the retrievals was measured using a structured light scanner. Then, a reference surface that included the deformation, but not the wear that the retrievals had experienced in vivo, was constructed using a fully automatic surface reconstruction algorithm. Finally, wear volume was calculated from the deviation between the worn and reconstructed surfaces. The measurement and analysis techniques were validated and the algorithm was found to produce errors of only 0.2% relative to the component volumes. In addition to quantifying cohort-level wear rates, the effect of mechanical axis limb alignment on mediolateral wear distribution was examined for a subset of the retrievals (n = 14 + 26). Our results show that FB implants produce significantly (p = 0.04) higher topside wear rates (24.6 ± 10.1 mm 3 /year) than rotating-platform implants (15.3 ± 8.0 mm 3 /year). This effect was larger than that of limb alignment, which had a smaller and nonsignificant influence on overall wear rates (+4.5 ± 11.6 mm 3 /year, p = 0.43). However, increased varus alignment was associated significantly with greater medial compartment wear in both the FB and rotating-platform designs (+1.7 ± 1.3%/° and +1.8 ± 1.6%/°). Our findings emphasize the importance of implant design and limb alignment on wear outcomes, providing reference data for improving implant performance and longevity., (© 2023 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Implant malalignment has been reported to be a primary reason for revision total knee arthroplasty (TKA). In addition, altered muscle coordination patterns are commonly observed in TKA patients, which is thought to alter knee contact loads. A comprehensive understanding of the influence of surgical implantation and muscle recruitment strategies on joint contact mechanics is crucial to improve surgical techniques, increase implant longevity, and inform rehabilitation protocols. In this study, a detailed musculoskeletal model with a 12 degrees of freedom knee was developed to represent a TKA subject from the CAMS-Knee datasets. Using motion capture and ground reaction force data, a level walking cycle was simulated and the joint movement and loading patterns were estimated using a novel technique for concurrent optimization of muscle activations and joint kinematics. In addition, over 12'000 Monte Carlo simulations were performed to predict knee contact mechanics during walking, considering numerous combinations of implant alignment and muscle activation scenarios. Validation of our baseline simulation showed good agreement between the model kinematics and loading patterns against the in vivo data. Our analyses reveal a considerable impact of implant alignment on the joint kinematics, while variation in muscle activation strategies mainly affects knee contact loading. Moreover, our results indicate that high knee compressive forces do not necessarily originate from extreme kinematics and vice versa. This study provides an improved understanding of the complex inter-relationships between loading and movement patterns resulting from different surgical implantation and muscle coordination strategies and presents a validated framework towards population-based modelling in TKA., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Knowledge of both tibio-femoral kinematics and kinetics is necessary for fully understanding knee joint biomechanics, guiding implant design and testing, and driving and validating computational models. In 2017, the CAMS-Knee datasets were presented, containing synchronized in vivo implant kinematics measured using a moving fluoroscope and tibio-femoral contact loads measured using instrumented implants from six subjects. However, to date, no representative summary of kinematics and kinetics obtained from measurements at the joint level of the same cohort of subjects exists. In this study, we present the CAMS-Knee standardized subject "Stan", whose reference data include tibio-femoral kinematics and loading scenarios from all six subjects for level and downhill walking, stair descent, squat and sit-to-stand-to-sit. Using the peak-preserving averaging method by Bergmann and co-workers, we derived scenarios for generally high (CAMS-HIGH100), peak, and extreme loading. The CAMS-HIGH100 axial forces reached peaks between 3022 and 3856 N (3.08-3.93 body weight) for the five investigated activities. Anterior-posterior forces were about a factor of ten lower. The axial moment around the tibia was highest for level walking and squatting with peaks of 9.4 Nm and 10.5 Nm acting externally. Internal tibial rotations of up to 8.4° were observed during squat and sitting, while the walking activities showed approximately half the internal rotation. The CAMS-HIGH100 loads were comparable to Bergmann and co-workers', but have the additional benefit of synchronized kinematics. Stan's loads are +11 to +56% higher than the ISO 14243 wear testing standard loads, while the kinematics exhibit markedly different curve shapes. Along with the original CAMS-Knee datasets, Stan's data can be requested at cams-knee.orthoload.com., (Copyright © 2022. Published by Elsevier Ltd.)

Tracing the source of origin of illegal ivory will contribute to the identification of poorly managed game parks and facilitate steps taken to prevent the African elephant from becoming extinct. This study was aimed at establishing a database on the composition of ivory obtained from elephant sanctuary areas in Southern Africa. Fragments of elephant ivory from seven geographically distinct areas in South Africa, Namibia and Botswana were analysed for inorganic and organic content. A total of 20 elements was detected in the inorganic fraction of ivory, some in concentrations as low as 0.25 microg/g. The concentrations of calcium, phosphate, magnesium, fluoride, cobalt and zinc showed statistically significant differences (p < 0.007) between ivory obtained from different regions. Analyses of the organic fraction identified 17 amino acids. Ivory from arid regions showed significantly lower proline plus hydroxyproline content and under-hydroxylation of lysine residues. This study indicates that chemical analyses of ivory could be beneficial in tracing the source of illegal ivory.

During an epidemiological survey of 181 individuals working or residing in the Kalahari National Gemsbok Park, swabs were taken from the dorsal surfaces of their tongues to determine a possible association between oral yeasts and clinically observed oral lesions as well as other underlying conditions detectable by serum chemistry. Identification of yeasts was performed with a commercially available identification system, namely the ATB 32C (Montalieu, Vercieu). Yeasts were isolated from 30.4 per cent (n = 55) of individuals, of whom 43.6 per cent (n = 24) had only Candida albicans, 3.6 per cent (n = 2) had C. albicans together with other yeasts and 52.7 per cent (n = 29) had other yeasts. Many of these yeasts were not the commonly encountered clinical isolates. The results revealed a significant association (p < 0.02) between yeasts (n = 55) and low serum iron concentrations (n = 50). A highly significant (p < 0.001) association was also found between smoking (n = 112) and the presence of clinically detectable oral lesions, notably leukoplakia (n = 21) and mucosal atrophy. The findings of this study reveal that a significant association exists between the oral yeast flora and serum iron and glucose, as well as between smoking and oral mucosal lesions.

Many factors have been cited as possible reasons for the decline in the number of wild dogs (Lycaon pictus), but few studies have provided supportive data. Between 1990 and 1993, the dynamics of 10 wild dog packs in the southern district of the Kruger National Park in South Africa were monitored. Casual observations of the causes of disease and mortality in the entire population were also recorded. During the same period, 46 wild dogs were immobilised, weighed, and subjected to physical examination as well as the collection of blood and faecal specimens. External parasites were collected and blood smears were prepared. Serum specimens were subjected to routine blood chemistry analyses, hormone and serological assays and formalinised blood specimens and faeces were subjected to screening for endoparasites. The study population varied from 75 in 1990 to 123 in 1993 with a survival rate of 29.9% for pups, 64.3% for yearlings and 69% for adults. Eighty per cent or more of the population were under 4 years of age. The cause of death in all wild dogs in the Kruger National Park could be established only in a small number of cases. Lions were responsible for the death of 20/62 wild dogs and disease caused the death of 6/62 wild dogs. All immobilised dogs were in a good physical condition, but 85% of dogs had one or more skin lesions. Potential life-threatening lesions (bitewounds inflicted by other dogs and lesions inflicted by a snare) occurred in 4 dogs. One male dog had only one testicle in the scortum. Twenty-six (93%) blood smears were positive for gametocytes of Hepatozoon sp., presumably H. canis, and in 2 dogs trophozoites of Babesia canis were seen. Eighty-six per cent of the specimens were positive for Dipetalonema reconditum. All dogs were infested with ticks and Haemaphysalis leachi, Amblyomma hebraeum, A. marmoreum, Boophilus decoloratus, Rhipicephalus simus, R. evertsi, R. appendiculatus and R. zambesiensis were identified. Ctenocephalides sp. and Echidnophaga larina were also identified. Taenia sp., Toxascaris canis and Ancylostoma caninum were present in faecal specimens. Antibody titres to adenovirus (26/31), B. canis (6/15), canine para-influenza virus (21/31), coronavirus (20/31), Coxiella burnetti (8/29), reovirus Type 3 (9/31), Rickettsia conori/africae (27/29), rotavirus (16/31) and Toxoplasma gondii (16/16) were found. The average serum urea concentration was higher (16.4 mmol/e) than that described for captive wild dogs, but other biochemical parameters were generally in agreement with values reported for captive wild dogs.(ABSTRACT TRUNCATED AT 400 WORDS)

The cupruretic effect of 2 copper chelators, d-penicillamine and trientine, was assessed in 12 fistulated South African Mutton Merino rams of approximately 6 mo age following copper loading. Each animal received 20 mg CuSO4.5H(2)0/kg body mass as an 0.5% m/v aqueous solution, intraruminally, daily for 35 d. The animals were randomly assigned to either a d-penicillamine (n = 4) or trientine treatment group (n = 4) or an unmedicated control group (n = 4). A separate group of 3 rams were kept as non-copper-loaded controls. Urinary copper excretion was measured before and during treatment. All the sheep were housed individually or placed intermittently on steel metabolic crates to facilitate urine collection. At the end of the trial the animals were euthanatized and specimens of organs collected for determination of copper concentrations. d-Penicillamine significantly (p < 0.05) increased urinary copper excretion. Trientine failed to increase copper excretion in the urine when compared to the unmedicated and non-copper-loaded control groups.

The concentrations of sodium, potassium, chloride, urea, creatinine, uric acid, total protein, albumin, inorganic phosphorous, calcium, magnesium, cholesterol, triglyceride, glucose, aspartate and alanine transaminases (AST and ALT), creatine kinase (CK), lactic acid dehydrogenase (LD), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP) and total bilirubin in the serum of a captive population of the mountain tortoise (Geochelone pardalis) (n = 13) were determined. Results varied considerably, particularly for most enzymes such as AST (11-113 U/l,ALT (1-72 U/l), CK (12-242 U/l), LD (147-2641 U/l) and ALP (56-168 U/l).

A tiletamine hydrochloride/zolazepam hydrochloride combination was used successfully to immobilize captive untamed wild dogs (Lycaon pictus) (n = 16) at dosage rates ranging from 2.3 to 32.3 mg/kg. Animals remained immobilized for periods ranging from 35 min to 24 hr 14 min. There was a significant positive correlation (r = 0.85, P less than 0.01) between dosage rate and the time immobilized. Profuse salivation and intermittent mild myoclonal contractions were observed in some wild dogs. Mildly reduced partial oxygen and carbon dioxide pressures as well as reduced concentrations of bicarbonate were observed in arterial blood at 10 and 20 min after administration of the drug. Serum concentrations of sodium, potassium, chloride, phosphorus, calcium, magnesium, urea, creatinine, glucose, proteins, albumin, gammaglutamyltransferase, creatinine kinase, aspartate transaminase, alkaline phosphatase, lactate dehydrogenase, insulin, cortisol and thyroxine are presented. These concentrations were found to be in agreement with values previously reported for wild dogs.

Selected haematological, blood chemical and serological variables were investigated in healthy Thoroughbreds (n = 45) in training. Haemoglobin concentration, haematocrit, red, white and differential cell counts as well as serum concentrations of total and ionized calcium, sodium, potassium, chloride, urea, creatinine, total protein, albumin, inorganic phosphorus, total bilirubin, iron, glucose, magnesium, alkaline phosphatase, gamma-glutamyltransferase, lactate dehydrogenase, aspartate transaminase, alanine transaminase and creatine kinase were found to be within ranges previously reported for horses. No statistically significant difference was found between the haematocrit (Ht) of horses n = 44; mean = 0.44; SD = 0.02) of different performance or between those of different age groups. A significant difference was found between the Ht of males (mean = 0.43; SD = 0.02) and females (mean = 0.45; SD = 0.02) and between quiet (mean = 0.44; SD = 0.02) and excitable (mean = 0.46; SD = 0.02) horses. No significant difference in red cell potassium concentration was found between horses of different performance. Cortisol, insulin, parathormone (C-terminal), aldosterone and folate concentrations respectively varied between 89-204 (mean = 144.4; SD = 25.47) nmol l-1, 4.2-23 (mean = 10; SD = 4.30) m U l-1, 65.2-91.4 (mean = 79.46; SD = 9.34) pmol l-1, less than 138 to 379 pmol l-1 and 9.4-21.5 (mean 14.5; SD = 2.87) nmol l-1. Vit B12 concentrations exceeded 1400 pmol l-1. Blood lead concentrations in all animals were below 15 ug l-1. Fifteen (33.3%) of the horses were carriers of babesiosis. Laboratory findings concerning these horses did not differ from those of the other horses.

Specimens from parotid salivary glands of full-grown elephant (Loxodonta africana) a (n=6) and saliva aspirated from their main excretory ducts were examined macroscopically and microscopically and analyzed biochemically. The composition of the saliva was compared to that of the blood. The parotids (n=12; mean = 7.4 kg) are homocrine and of a seromucous nature. Myoepithelial cells are well-developed along intercalated ducts and their processes extend to proximal portions of allied acini. The saliva is hypotonic and contains relatively low concentrations of sodium and glucose and high concentrations of potassium, urea, calcium and phosphorus. Absence of detectable levels of alpha-amylase negates a digestive role and the voluminous secrete evidently aids swallowing by moisturising and lubricating the large mass of ingested leaves, grass and bark.

Ionized and total calcium levels were determined in 29 Friesian and 5 Drakensberger cows. One Friesian cow had parturient paresis and specimens were taken before and after treatment. It is suggested that due to the easy reliable way in which ionized calcium levels can now be determined this investigation should replace total calcium estimations in dairy cows presenting with parturient paresis. Ionized calcium levels serve as a valuable diagnostic aid but are also important to assess the effectivity of treatment for this condition.

The weight of Rhipicephalus evertsi evertsi Neumann nymphs, which as larvae and nymphs completed the entire blood meal on the same individual guinea pig, was significantly lower than the weight of those that as larvae and nymphs fed on two separate naive hosts. Nymphs of the latter category spent 1 wk (from unfed larvae to unfed nymphs) on one animal before their transfer to the second host to complete the blood meal. The albumin concentration of the host blood decreased and was related to the time that the immature ticks spent on the hosts. The albumin/globulin ratio also decreased. The alpha 1 globulin fraction increased soon after the guinea pigs were infested with ticks. No further changes in the levels of the alpha 1 globulin fraction were observed with time. The concentration of serum beta globulins increased only in guinea pigs infested with immature ticks for the entire larval and nymphal feeding period. A second infestation of those guinea pigs with larvae of R. e. evertsi resulted in further increases in the levels of serum beta globulins. The relationships among serum beta globulin levels, the weight of engorged nymphs, and host immunity are discussed.

Serum concentrations of sodium, potassium, chloride, total protein, albumin, aspartate transaminase, creatine kinase, lactate dehydrogenase, gamma-glutamyltranspeptidase, alkaline phosphatase and alanine transaminase were determined in free-living white rhinoceroses Ceratotherium simum (n = 20). Single serum cortisol (n = 20), oestradiol-17 Beta (n = 14) and progesterone (n = 14) concentrations are also presented. Low serum sodium (129.6 +/- 4.2 mmol/l) chloride (94.2 +/- 3.05 mmol/l) and albumin (26.1 +/- 3.71 mmol/l) as well as high globulin (alpha 1, alpha 2, beta and gamma) concentrations were outstanding features.

Venous whole-blood samples for the determination of lead concentrations were obtained from hippopotami (Hippopotamus amphibius) (n = 26) during a population control programme on the banks of the Sabie River. A mean blood lead concentration of 26.3 micrograms l-1 was lower than the mean concentration of 34.0 micrograms l-1 cited for a group of young people living in a remote area where lead pollution was considered to be negligible. These concentrations indicate that lead pollution in this area of the Kruger National Park is at present low.

The sodium contents of six differently prepared oral rehydration solutions (ORS) were measured. A total of 452 solutions were prepared in our gastro-enteritis unit. The finger-pinch-and-cup method produced sodium values that were too high and too variable. The most acceptable sodium level was achieved using half a 5 ml medicine teaspoon or 1 level common household teaspoon of salt in 1 litre of water. Half a commonly available household teaspoon of salt caused sodium levels to be low but still acceptable and safe. We recommend that half a teaspoon of salt in 1 litre of water be used when preparing an ORS.

Serum levels of sodium, potassium, chloride, phosphorus, iron, total magnesium, total calcium, alkaline phosphatase, alanine transaminase, lactate dehydrogenase, creatine kinase, gamma-glutamyltransferase, aspartate transaminase, urea, creatinine, total protein, albumin and plasma glucose were determined in 49 ostriches (Struthio camelus) kept under semi-extensive conditions.

Concentrations of sodium, potassium, chloride, inorganic phosphorus, total magnesium, total calcium, iron, urea, creatinine, total protein, albumin, total bilirubin, alkaline phosphatase (ALP), alanine transaminase (ALT), lactate dehydrogenase (LD), creatine kinase (CK), gamma-glutamyltransferase (GGT) and aspartate transaminase (AST) were determined in serum specimens collected from 53 free-ranging mountain reedbuck (Redunca fulvorufula) during live capture using nets. Considerable variations in the concentrations of the enzymes ALP, LDH, CK, GGT and AST were found as well as in the concentrations of creatinine, bilirubin and iron. This wide variation in results seriously questions the usefulness of similar blood investigations on heterogenous groups of mechanically restrained animals.

Concentrations of sodium, potassium, chloride, inorganic phosphorus, total calcium, total magnesium, albumin, total protein, cholesterol, urea, creatinine, cortisol as well as the activities of alkaline phosphatase, alanine transaminase, aspartate transaminase, gamma-glutamyltransferase, creatine kinase and lactate dehydrogenase were determined in serum specimens collected from 100 free-ranging warthogs Phacochoerus aethiopicus within five minutes after they were killed with a shotgun. Average concentrations for the following chemical constituents were found: sodium (145 mmol l-1), potassium (8.6 mmol l-1), chloride (102.5 mmol l-1), phosphorus (2.31 mmol l-1), calcium (2.93 mmol l-1), magnesium (1.23 mmol l-1), albumin (26.4 g l-1), serum proteins (62.2 g l-1), cholesterol (1.82 mmol l-1) and urea (8.74 mmol l-1). The cortisol concentrations ranged from 55-340 nmol l-1 (n = 30). Wide variations were recorded in the concentration of creatinine as well as in the activities of the various enzymes.