In vitro elution characteristics of gentamicin- and teicoplanin-loaded CMW1 and Palacos R bone cement.

PURPOSE: To compare the in vitro elution characteristics of CMW1 and Palacos R bone cement loaded with gentamicin, teicoplanin, or in combination. METHODS: Four bone cement discs were prepared for each cement type. Disc 1 contained no antibiotics; disc 2 contained 0.5 g gentamicin; disc 3 contained 2 g teicoplanin; disc 4 contained 0.5 g gentamicin and 2 g teicoplanin. Elution studies were conducted using a fluorescence polarisation immunoassay technique and performed at intervals of 6 weeks. RESULTS: For CMW1, gentamicin and teicoplanin elution levels in combination discs were higher than those in the single antibiotic discs (p < 0.001 & p < 0.06). For Palacos R, gentamicin elution levels in combination discs were higher than those in the single antibiotic discs (p < 0.001), but teicoplanin elution levels in combination discs were lesser than that from the single antibiotic discs (p < 0.02). In single and combination discs, gentamicin elution levels in Palacos R were higher than those in CMW1 (p < 0.001 & p < 0.001). Palacos R eluted more teicoplanin than CMW1, except in combined disc with gentamicin, when less teicoplanin was eluted. CONCLUSION: Antibiotic elution is higher in Palacos R than CMW1. Antibiotic combination in both cement types has the synergistic effect of increasing antibiotic elution, except for teicoplanin from Palacos R. When high elution of gentamicin is required, Palacos R is preferable. When high elution of teicoplanin is required, Palacos R with only teicoplanin is superior to CMW1.

Acute liver failure in Scotland: changes in aetiology and outcomes over time (the Scottish Look-Back Study).

BACKGROUND: Acute liver failure is a rare and devastating clinical condition resulting from sudden loss of hepatic parenchyma and metabolic function. The Scottish Liver Transplant Unit (SLTU) offers specialist management and emergency liver transplantation to patients with acute liver failure from across Scotland. AIM: To describe temporal changes in number of admissions, aetiology of acute liver failure, severity of disease at presentation and outcomes over a 22-year period. METHODS: Retrospective analysis of the SLTU database, including all patients admitted with acute liver injury or acute liver failure between November 1992 and March 2014. RESULTS: There has been no change in the number of patients presenting with acute liver injury or failure secondary to paracetamol overdose, but a reduction in the number of admissions with acute liver injury or failure secondary to non paracetamol causes. Over time, disease severity at presentation has not changed in the paracetamol cohort; those with a non paracetamol aetiology have latterly presented with milder hepatic encephalopathy. Spontaneous survival rates improved significantly over time for those patients with acute liver failure due to paracetamol and non paracetamol aetiologies. The most marked improvement in survival is observed in the sickest patients meeting Kings College Hospital poor prognostic criteria. CONCLUSIONS: The number of admissions to the SLTU with acute liver failure is decreasing, due to reduced numbers of non paracetamol cases. Outcomes in this condition are improving, due to improvements in intensive care management and use of liver transplantation, and the increase in survival is most marked in patients meeting Kings College Hospital poor prognostic criteria.

The sequential organ failure assessment (SOFA) score is an effective triage marker following staggered paracetamol (acetaminophen) overdose.

BACKGROUND: The sequential organ failure assessment (SOFA) score is an effective triage marker following single time point paracetamol (acetaminophen) overdose, but has not been evaluated following staggered (multiple supratherapeutic doses over >8 h, resulting in cumulative dose of >4 g/day) overdoses. AIM: To evaluate the prognostic accuracy of the SOFA score following staggered paracetamol overdose. METHODS: Time-course analysis of 50 staggered paracetamol overdoses admitted to a tertiary liver centre. Individual timed laboratory samples were correlated with corresponding clinical parameters and the daily SOFA scores were calculated. RESULTS: A total of 39/50 (78%) patients developed hepatic encephalopathy. The area under the SOFA receiver operator characteristic for death/liver transplantation was 87.4 (95% CI 73.2-95.7), 94.3 (95% CI 82.5-99.1), and 98.4 (95% CI 84.3-100.0) at 0, 24 and 48 h, respectively, postadmission. A SOFA score of <6 at tertiary care admission predicted survival with a sensitivity of 100.0% (95% CI 76.8-100.0) and specificity of 58.3% (95% CI 40.8-74.5), compared with 85.7% (95% CI 60.6-97.4) and 75.0% (95% CI 65.2-79.5) , respectively, for the modified Kings College criteria. Only 2/21 patients with an admission SOFA score <6 required renal replacement therapy or intracerebral pressure monitoring. SOFA significantly outperformed the Model for End-stage Liver Disease, but not APACHE II, at 0, 24-and 48-h following admission. CONCLUSIONS: A SOFA score <6 at tertiary care admission following a staggered paracetamol overdose, is associated with a good prognosis. Both the SOFA and APACHE II scores could improve triage of high-risk staggered paracetamol overdose patients.

Identification of trabecular excrescences, novel microanatomical structures, present in bone in osteoarthropathies.

It is widely held that bone architecture is finely regulated in accordance with homeostatic requirements. Aberrant remodelling (hyperdensification and/or cyst formation in the immediately subchondral region) has previously been described in bone underlying cartilage in arthropathies. The present study examined the trabecular architecture of samples of bone, initially in the severe osteoarthropathy of alkaptonuria, but subsequently in osteoarthritis using a combination of light microscopy, 3D scanning electron microscopy and quantitative backscattered electron scanning electron microscopy. We report an extraordinary and previously unrecognised bone phenotype in both disorders, including novel microanatomical structures. The underlying subchondral trabecular bone contained idiosyncratic architecture. Trabecular surfaces had numerous outgrowths that we have termed "trabecular excrescences", of which three distinct types were recognised. The first type arose from incomplete resorption of branching secondary trabeculae arising from the deposition of immature (woven) bone in prior marrow space. These were characterised by very deeply scalloped surfaces and rugged edges. The second type had arisen in a similar way but been smoothed over by new bone deposition. The third type, which resembled coarse stucco, probably arises from resting surfaces that had been focally reactivated. These were poorly integrated with the prior trabecular wall. We propose that these distinctive microanatomical structures are indicative of abnormal osteoclast/osteoblast modelling in osteoarthropathies, possibly secondary to altered mechanical loading or other aberrant signalling. Identification of the mechanisms underlying the formation of trabecular excrescences will contribute to a better understanding of the role of aberrant bone remodelling in arthropathies and development of new therapeutic strategies.

The sequential organ failure assessment (SOFA) score is prognostically superior to the model for end-stage liver disease (MELD) and MELD variants following paracetamol (acetaminophen) overdose.

BACKGROUND: The prognostic value of the model for end-stage liver disease (MELD) and sodium-based MELD variants in predicting survival following paracetamol overdose remains unclear. AIM: To examine the prognostic accuracy of sodium-based MELD variants in paracetamol-induced acute liver injury compared with the sequential organ failure assessment (SOFA) score. METHODS: Retrospective analysis of 138 single time point paracetamol overdoses admitted to a tertiary liver centre. Individual laboratory samples were correlated with the corresponding clinical parameters in relation to time post-overdose, and the daily MELD, MELD-Na, MELDNa, MESO, iMELD, UKELD, updated MELD and SOFA scores were calculated. RESULTS: Sixty-six (47.8%) patients developed hepatic encephalopathy, of whom 7 were transplanted and 21 died without liver transplantation. SOFA had a significantly greater area under the receiver operator characteristic for the prediction of spontaneous survival compared with MELD at both 72 (P = 0.024) and 96 (P = 0.017) h post-overdose. None of the sodium-based MELD variants improved the prognostic accuracy of MELD. A SOFA score >6 by 72 h or >7 by 96 h, post-overdose predicted death/transplantation with a negative predictive value of 96.9 (95% CI 90.2-99.4) and 98.8 (95% CI 93.6-99.9) respectively. SOFA and MELD had similar accuracy for predicting the development of hepatic encephalopathy (P = 0.493). CONCLUSIONS: The SOFA score is superior to MELD in predicting spontaneous survival following paracetamol-induced acute liver injury. Modification of the MELD score to include serum sodium does not improve prognostic accuracy in this setting. SOFA may have potential as a quantitative triage marker following paracetamol overdose.

The role of calcified cartilage and subchondral bone in the initiation and progression of ochronotic arthropathy in alkaptonuria.

OBJECTIVE: Alkaptonuria is a genetic disorder of tyrosine metabolism, resulting in elevated circulating concentrations of homogentisic acid. Homogentisic acid is deposited as a polymer, termed ochronotic pigment, in collagenous tissues, especially cartilages of weight-bearing joints, leading to a severe osteoarthropathy. We undertook this study to investigate the initiation and progression of ochronosis from the earliest detection of pigment through complete joint failure. METHODS: Nine joint samples with varying severities of ochronosis were obtained from alkaptonuria patients undergoing surgery and compared to joint samples obtained from osteoarthritis (OA) patients. Samples were analyzed by light and fluorescence microscopy, 3-dimensional scanning electron microscopy (SEM), and the quantitative backscattered electron mode of SEM. Cartilage samples were mechanically tested by compression to determine Young's modulus of pigmented, nonpigmented, and OA cartilage samples. RESULTS: In alkaptonuria samples with the least advanced ochronosis, pigment was observed intracellularly and in the territorial matrix of individual chondrocytes at the boundary of the subchondral bone and calcified cartilage. In more advanced ochronosis, pigmentation was widespread throughout the hyaline cartilage in either granular composition or as blanket pigmentation in which there is complete and homogenous pigmentation of cartilage matrix. Once hyaline cartilage was extensively pigmented, there was aggressive osteoclastic resorption of the subchondral plate. Pigmented cartilage became impacted on less highly mineralized trabeculae and embedded in the marrow space. Pigmented cartilage samples were much stiffer than nonpigmented or OA cartilage as revealed by a significant difference in Young's modulus. CONCLUSION: Using alkaptonuria cartilage specimens with a wide spectrum of pigmentation, we have characterized the progression of ochronosis. Intact cartilage appears to be resistant to pigmentation but becomes susceptible following focal changes in calcified cartilage. Ochronosis spreads throughout the cartilage, altering the mechanical properties. In advanced ochronosis, there is aggressive resorption of the underlying calcified cartilage leading to an extraordinary phenotype in which there is complete loss of the subchondral plate. These findings should contribute to better understanding of cartilage-subchondral interactions in arthropathies.

Chronic kidney disease after liver transplantation for acute liver failure is not associated with perioperative renal dysfunction.

Renal dysfunction of acute liver failure (ALF) may have distinct pathophysiological mechanisms to hepatorenal syndrome of cirrhosis. Yet, the impact of perioperative renal function on posttransplant renal outcomes in ALF patients specifically has not been established. The aims of this study were (1) to describe the incidence and risk factors for chronic renal dysfunction following liver transplantation for ALF and (2) to compare renal outcomes with age-sex-matched patients transplanted for chronic liver disease. This was a single-center study of 101 patients transplanted for ALF. Fifty-three-and-a-half percent had pretransplant acute kidney injury and 64.9% required perioperative renal replacement therapy. After transplantation the 5-year cumulative incidence of chronic kidney disease (eGFR <60 mL/min/1.73 m²) was 41.5%. There was no association between perioperative acute kidney injury (p = 0.288) or renal replacement therapy (p = 0.134) and chronic kidney disease. Instead, the independent predictors of chronic kidney disease were older age (p = 0.019), female gender (p = 0.049), hypertension (p = 0.031), cyclosporine (p = 0.027) and nonacetaminophen-induced ALF (p = 0.039). Despite marked differences in the perioperative clinical condition and survival of patients transplanted for ALF and chronic liver disease, renal outcomes were the same. In conclusion, in patients transplanted for ALF the severity of perioperative renal injury does not predict posttransplant chronic renal dysfunction.

The systemic inflammatory response syndrome and sequential organ failure assessment scores are effective triage markers following paracetamol (acetaminophen) overdose.

BACKGROUND: The systemic inflammatory response syndrome (SIRS) and sequential organ failure assessment (SOFA) scores are widely used as prognostic markers in critical care settings and could improve triage of high-risk paracetamol (acetaminophen) overdose patients. AIM: To evaluate the prognostic accuracy of the SIRS and SOFA scores following single time point paracetamol overdose. METHODS: Analysis of 100 single time point paracetamol overdoses admitted to a tertiary liver centre, with subsequent prospective validation of identified thresholds. Individual laboratory samples were correlated with the corresponding clinical parameters in relation to time post-overdose, and the daily SOFA and SIRS scores calculated. RESULTS: A total of 74 (74%) patients developed the SIRS, which occurred significantly earlier in patients who died (n=21) compared with spontaneous survivors (n=53, P=0.05). The SIRS occurred in 70 (70%) patients by 96h post-overdose, with a 30% mortality rate; compared with 0% mortality in the 30 non-SIRS patients (P=0.001). Median SOFA scores were significantly higher in nonsurvivors at 48 (P=0.009), 72 (P<0.001), and 96h (P<0.001). A SOFA score >7 during the first 96h post-overdose predicted death/transplantation with a sensitivity of 95.0 (95% CI 78.5-99.1) and specificity of 70.5 (95% CI 66.3-71.6). A validation cohort of 38 single time point paracetamol overdoses confirmed the extremely high negative predictive value of both the SIRS and SOFA thresholds. CONCLUSIONS: The absence of either a SOFA score >7 or a SIRS response during the first 96 h following paracetamol overdose could improve triage and reduce transfers of lower risk patients to tertiary liver centres.

The R563Q mutation of the epithelial sodium channel beta-subunit is associated with hypertension.

BACKGROUND: A high prevalence of the R563Q mutation of the epithelial sodium channel ß-subunit has been reported in South African hypertensives compared with unrelated normotensive controls. To delineate the effects of this mutation against a more uniform genetic background, this study investigated the association of the mutation with hypertension within affected kindreds. METHODS: Forty-five index patients and members of their kindreds were studied. Blood pressure, serum potassium and the presence of the R563Q mutation were determined. RESULTS: Of the 136 individuals studied, 89 were heterozygous for the R563Q mutation and 47 homozygous RR. The mean arterial pressure was significantly higher in the R563Q heterozygous group (p = 0.005) after adjusting for gender, race, age and kindred membership. Of the R563Q heterozygous subjects, 71 (80%) had hypertension, while 17 (36%) of the R563Q homozygous RR subjects were hypertensive. Six R563Q heterozygous subjects had hypokalaemia and one R563Q homozygous RR subject had hypokalaemia, but the difference was not statistically significant. Two heterozygous patients had Liddle's syndrome, both occurring during pregnancy. CONCLUSION: The R563Q mutation of ß-ENaC is associated with hypertension within affected kindreds, but does not usually cause the full Liddle's syndrome phenotype.

The systemic inflammatory response syndrome is predictive of renal dysfunction in patients with non-paracetamol-induced acute liver failure.

BACKGROUND: Although renal dysfunction is a common complication of acute liver failure (ALF) with significant prognostic implications, the pathophysiological mechanisms remain unclear. The current hypothesis suggests that the renal dysfunction may mirror the hepatorenal syndrome of cirrhosis. However, ALF has distinct clinical characteristics and the circulatory derangement may be more comparable with sepsis. OBJECTIVES: To examine the relationship between the systemic inflammatory response syndrome (SIRS) and renal dysfunction in ALF, and to identify additional risk factors for renal dysfunction. METHODS: A single-centre retrospective study of 308 patients with ALF was carried out. Renal dysfunction was defined according to the RIFLE criteria for acute kidney injury. RESULTS: 67% of patients developed renal dysfunction. On univariate analysis, renal dysfunction patients were more likely to be hypothermic (p = 0.010), had a faster heart rate (p<0.001), a higher white cell count (p = 0.001) and a lower PaCO(2) (p = 0.033). 78% of renal dysfunction patients and 53% of non-renal dysfunction patients had SIRS (p<0.001). On multivariate analysis, the risk factors for renal dysfunction were age (p = 0.024), fulfilled Kings College Hospital prognostic criteria (p<0.001), hypotension (p<0.001), paracetamol-induced ALF (p<0.001), infection (p = 0.077) and SIRS (p = 0.017). SIRS remained an independent predictor of renal dysfunction in the subgroup of patients with non-paracetamol-induced ALF (n = 91, p = 0.001). In contrast, in patients with paracetamol-induced ALF (n = 217), no relationship between SIRS and renal dysfunction was demonstrated (p = 0.373). CONCLUSION: SIRS is strongly associated with the development of renal dysfunction in patients with non-paracetamol-induced ALF. It is proposed that the systemic inflammatory cascade plays a key role in its pathogenesis.

Association of pre-eclampsia with the R563Q mutation of the beta-subunit of the epithelial sodium channel.

The R563Q mutation of the beta-subunit of the epithelial sodium channel (ENaC) is associated with hypertension in black and mixed ancestry (MA) men and women in South Africa. The frequency of the R563Q mutation in black and MA women with pre-eclampsia (n= 230) and in controls (n= 198) was studied. The R563Q mutation was found in 7.8% of the women with pre-eclampsia and in 2.6% of controls (P= 0.014). This remained significant if the black women were analysed separately (P= 0.031). We have demonstrated that a genetic variant of the ENaC is associated with pre-eclampsia. This has implications for understanding the pathogenesis and treatment of pre-eclampsia.

Heterophile antibodies may cause falsely lowered serum cortisol values.

OBJECTIVE: We describe a case where interference by heterophile antibodies in a cortisol immunoassay led to a falsely lowered serum cortisol level. CASE DATA: As part of a diagnostic workup for fatigue, a 42-yr-old woman was found to have a low 9.00 h serum cortisol and an abnormal Synacthen stimulation test consistent with adrenal insufficiency. On insulin hypoglycemia testing, markedly discrepant cortisol levels were obtained from paired samples tested by two different immunoassays. Further tests, including plasma ACTH and overnight metyrapone test, confirmed normal hypothalamic-pituitary-adrenal axis function. Negative interference on the initial immunoassay from a heterophile antibody in the patient's serum was detected, thereby explaining the abnormal results. CONCLUSIONS: This report demonstrates that potentially significant consequences can arise from the failure to consider heterophile antibody interference. Clinicians who interpret test results need to be aware of the potential for interference in immunoassays by heterophile antibodies.

Screening for primary aldosteronism--normal ranges for aldosterone and renin in three South African population groups.

OBJECTIVE: To establish normal ranges for plasma aldosterone, renin and aldosterone/renin (A/R) ratio in South African normotensives under typical outpatient conditions, and to estimate the prevalence of primary aldosteronism (PA) among hypertensives in primary care settings. DESIGN AND METHODS: One hundred and thirty-six normotensive subjects and 154 sex- and age-matched hypertensives at three primary care clinics had measurements of blood pressure, plasma creatinine, K+, aldosterone, plasma renin activity, and spot urine for urinary Na+/creatinine ratio. Medication was not withdrawn before testing. RESULTS: Mean plasma renin activity in black normotensive subjects (0.95 +/- 1.25 ng/ml/h, mean +/- standard deviation (SD)) was significantly lower than in white (2.09 +/- 1.12 ng/ml/h; P < 0.0001) and coloured (1.81 +/- 1.86 ng/ml/h, P = 0.013) normotensives. Mean plasma aldosterone in black normotensives (306 +/- 147 pmol/l) was also significantly lower than in white (506 +/- 324 pmol/l, P = 0.0002) and coloured (418 +/- 304 pmol/l, P = 0.0148) normotensives. In hypertensives, there were no significant differences in renin or aldosterone levels between the three population groups. Urinary Na+/creatinine ratios, an index of Na+ intake, were not significantly different in the three population groups. None of the normotensives had an A/R ratio > or = 1,000 plus aldosterone > or = 750, while 7.1% of hypertensives exceeded these levels, suggesting that they are appropriate criteria for screening for PA. CONCLUSIONS: A large fraction of black normotensive subjects had low renin and aldosterone levels compared with whites, suggesting a salt-retaining tendency in black subjects. These results have important implications for the interpretation of plasma renin and aldosterone levels in hypertensive patients. In primary care settings, 7.1% of hypertensives had biochemical results indicating the need for investigation of PA.

Simple treatment for torus fractures of the distal radius.

Torus (buckle) fractures of the distal radius are common in childhood. Based on the results of a postal questionnaire and a prospective, randomised trial, we describe a simple treatment for this injury, which saves both time and money. Over a six-month period, we randomised 201 consecutive patients with this injury to treatment with either a traditional forearm plaster-of-Paris cast or a 'Futura-type' wrist splint. All patients were treated for a period of three weeks, followed by clinical and radiological review. There was no difference in outcome between the two groups, and all patients had a good result. Only one patient did not tolerate the splint which was replaced by a cast. The questionnaire showed a marked variation in the way in which these injuries are treated with regard to the method and period of immobilisation, the number of follow-up visits and radiographs taken. We suggest that a 'Futura-type' wrist splint can be used to treat these fractures. The patient should be reviewed on the following day to confirm the diagnosis and to give appropriate advice. There is no evidence that further follow-up is required. This simple treatment has major benefits in terms of cost and reduction of the number of attendances.

Desensitization and internalization of human and xenopus gonadotropin-releasing hormone receptors expressed in alphaT4 pituitary cells using recombinant adenovirus.

Nonmammalian vertebrates express at least two forms of GnRH and distinct forms of GnRH receptor (GnRH-R) have coevolved with their ligands. Mammalian and nonmammalian GnRH-R have key structural differences (notably the lack of C-terminal tails in mammalian GnRH-R) and comparative studies are beginning to reveal their functional relevance. However, cellular context and receptor density influence G protein-coupled receptor function and may be important variables in such work using heterologous expression systems. Here we report a comparative study using alphaT4 cells (gonadotrope progenitors that lack endogenous GnRH-R) transfected with a mammalian (human) or nonmammalian (Xenopus laevis type I) GnRH-R. Because conventional transfection strategies proved inefficient, recombinant adenovirus expressing these receptors were constructed, enabling controlled and efficient GnRH-R expression. When expressed in alphaT4 cells at physiological density, these GnRH-Rs retain the pharmacology of their endogenous counterparts (as judged by ligand specificity in radioligand binding and inositol phosphate accumulation assays) but do not activate adenylyl cyclase and are not constitutively active. Moreover, the Xenopus GnRH-R rapidly desensitizes and internalizes in these cells, whereas the human GnRH-R does not, and the internalization rates are not dependent upon receptor number. These data extend studies in COS, HEK, and GH3 cells showing that other GnRH-R with C-terminal tails desensitize and internalize rapidly, whereas tail-less mammalian GnRH-R do not. Retention of these distinctions at physiological receptor density in gonadotrope lineage cells, supports the argument that the evolution of nondesensitizing mammalian GnRH-Rs is functionally relevant and related to the development of mammalian reproductive strategies.

In vitro elution of gentamicin, amikacin, and ceftiofur from polymethylmethacrylate and hydroxyapatite cement.

OBJECTIVE: To compare the elution characteristics of ceftiofur and liquid and powdered gentamicin and amikacin from polymethylmethacrylate (PMMA) and from hydroxyapatite cement (HAC). METHODS: PMMA and HAC beads in triplicate were impregnated with various amounts and formulations of antibiotics. Beads were immersed in 5 mL of phosphate buffered saline that was replaced at 1, 3, 6, and 12 hours, and 1, 2, 3, 5, 7, 10, 14, 18, 22, 26, and 30 days. The eluent was stored at -70 degrees C until assayed within 2 weeks by microbiological assay (gentamicin and amikacin) or capillary electrophoresis (ceftiofur). RESULTS: Rate of elution for all beads was greatest within the first 24 hours. Cumulative release of total antibiotic dose from beads over 30 days was significantly greater from HAC than PMMA. Antibiotic elution was directly related to the amount of antibiotic incorporated into the cement. Powdered and liquid forms of gentamicin had similar elution rates from PMMA. Elution of amikacin from PMMA beads was greater when the powdered form was used compared with liquid amikacin. Eluent concentrations of ceftiofur were similar to those of the aminoglycosides during the first 3 to 7 days but then decreased precipitously by comparison. CONCLUSIONS: Elution of antibiotics from HAC was greater than from PMMA. Gentamicin- and amikacin-impregnated PMMA and HAC released bactericidal concentrations of antibiotic for at least 30 days. Ceftiofur-impregnated PMMA or HAC is unlikely to provide long-term bactericidal concentrations. CLINICAL RELEVANCE: Gentamicin and amikacin elute effectively from PMMA and HAC.