Glenohumeral morphological predictors of recurrent shoulder instability following arthroscopic Bankart repair

PURPOSE

The purpose of this study was to evaluate glenohumeral morphological features on a magnetic resonance arthrogram (MRA) to determine risk factors for recurrence of anterior shoulder instability following arthroscopic Bankart repair (ABR).

METHODS

A retrospective review of patients who underwent ABR between 2012 and 2017 was performed to identify patients who had recurrence of instability following stabilisation (Group 1). These were pair-matched in a 2:1 ratio for age, gender and sport with a control (Group 2) who underwent ABR without recurrence. Preoperative MRAs were evaluated for risk factors for recurrence, with glenoid bone loss and Hill-Sachs lesions also measured. Multilinear and multilogistic regression models were used to evaluate factors affecting recurrence.

RESULTS

Overall, 72 patients were included in this study, including 48 patients without recurrence and 24 patients with recurrent instability. There was a significant difference between the two groups in mean glenoid bone loss (Group 1: 7.3% vs. Group 2: 5.7%, p < 0.0001) and the rate of off-track Hill-Sachs lesions (Group 1: 20.8% vs. Group 2: 0%, p = 0.0003). Of the variables analysed in logistic regression, increased glenoid anteversion (p = 0.02), acromioclavicular (AC) degeneration (p = 0.03) and increased Hill-Sachs width were associated with increased risk of failure. Increased chondral version (p = 0.01) and humeral head diameter in the anteriorposterior view were found to be protective and associated with a greater likelihood of success.

CONCLUSION

Glenoid anteversion was a risk factor for recurrent instability, whereas increased chondral version and humeral head diameter were associated with higher rates of success following ABR. Glenoid bone loss, presence of an off-track Hill-Sachs lesion, increased Hill-Sachs width and AC degeneration were also associated with failure. These findings should be used by surgeons to stratify risk for recurrence following ABR.

LEVEL OF EVIDENCE

Level III.

Neoadjuvant therapy does not impact the biliary microbiome in patients with pancreatic cancer

BACKGROUND

Pancreatic adenocarcinoma (PDAC) often impinges on the biliary tree and obstruction necessitates stent placement increasing the risk of surgical site infections (SSIs). We sought to explore the impact of neoadjuvant therapy on the biliary microbiome and SSI risk in patients undergoing resection.

METHODS

A retrospective analysis was performed on 346 patients with PDAC who underwent resection at our institution from 2008 to 2021. Univariate and multivariate methods were utilized for analysis.

RESULTS

Biliary stenting rates were similar between groups but resulted in increased bile culture positivity (97% vs. 15%, p < 0.001). Culture positivity did not differ between upfront resection or neoadjuvant chemotherapy (NAC) (77% vs. 80%, p = 0.60). NAC-alone versus neoadjuvant chemoradiotherapy did not impact biliary positivity (80% vs. 79%, p = 0.91), nor did 5-fluorouracil versus gemcitabine-based regimens (73% vs. 85%, p = 0.19). While biliary stenting increased incisional SSI risk (odds ratios [OR]: 3.87, p = 0.001), NAC did not (OR: 0.83, p = 0.54). Upfront resection, NAC, and chemoradiotherapy were not associated with biliary organism-specific changes or antibiotic resistance patterns.

CONCLUSIONS

Biliary stenting is the greatest predictor for positive biliary cultures and SSIs in resected PDAC patients. Neither NAC nor radiotherapy impact bile culture positivity, speciation, rates, or antibiotic resistance patterns, and perioperative antibiotic prophylaxis should not differ.

Evaluation of multiplex tandem PCR (MT-PCR) assays for the detection of bacterial resistance genes among Enterobacteriaceae in clinical urines

Background

Increasing resistance drives empirical use of less potent and previously reserved antibiotics, including for urinary tract infections (UTIs). Molecular profiling, without culture, might better guide early therapy.

Objectives

To explore the potential of AusDiagnostics multiplex tandem (MT) PCR UTI assays.

Methods

Two MT-PCR assays were developed successively, seeking 8 or 16 resistance genes. Amplification was tracked in real time, with melting temperatures used to confirm product identity. Assays were variously performed on: (i) extracted DNA; (ii) cultured bacteria; (iii) urine spiked with reference strains; and (iv) bacteria harvested from clinical urines. Results were compared with those from sequencing, real-time SybrGreen PCR or phenotypic susceptibility.

Results

Performance was similar irrespective of whether DNA, cultures or urines were used, with >90% sensitivity and specificity with respect to common β-lactamases, dfr genes and aminoglycoside resistance determinants except aadA1/A2/A3, for which carriage correlated poorly with streptomycin resistance. Fluoroquinolone-susceptible and -resistant Escherichia coli (but not other species) were distinguished by the melting temperatures of their gyrA PCR products. The time from urine to results was <3 h.

Conclusions

The MT-PCR assays rapidly identified resistance genes from Gram-negative bacteria in urines as well as from cultivated bacteria. Used directly on urines, this assay has the potential to guide early therapy.

The Unyvero P55 'sample-in, answer-out' pneumonia assay: A performance evaluation

Background

O’Neill’s recent Review on Antimicrobial Resistance expressed the view that by 2020 high-income countries should make it mandatory to support antimicrobial prescribing with rapid diagnostic evidence whenever possible.

Methods

Routine microbiology diagnosis of 95 respiratory specimens from patients with severe infection were compared with those generated by the Unyvero P55 test, which detects 20 pathogens and 19 antimicrobial resistance markers. Supplementary molecular testing for antimicrobial resistance genes, comprehensive culture methodology and 16S rRNA sequencing were performed.

Results

Unyvero P55 produced 85 valid results, 67% of which were concordant with those from the routine laboratory. Unyvero P55 identified more potential pathogens per specimen than routine culture (1.34 vs. 0.47 per specimen). Independent verification using 16S rRNA sequencing and culture (n = 10) corroborated 58% of additional detections compared to routine microbiology. Overall the average sensitivity for organism detection by Unyvero P55 was 88.8% and specificity was 94.9%. While Unyvero P55 detected more antimicrobial resistance markers than routine culture, some instances of phenotypic resistance were missed.

Conclusions

The Unyvero P55 is a rapid pathogen detection test for lower respiratory specimens, which identifies a larger number of pathogens than routine microbiology. The clinical significance of these additional organisms is yet to be determined. Further studies are required to determine the effect of the test in practise on antimicrobial prescribing and patient outcomes.

Identification of bacterial pathogens and antimicrobial resistance directly from clinical urines by nanopore-based metagenomic sequencing

OBJECTIVES

The introduction of metagenomic sequencing to diagnostic microbiology has been hampered by slowness, cost and complexity. We explored whether MinION nanopore sequencing could accelerate diagnosis and resistance profiling, using complicated urinary tract infections as an exemplar.

METHODS

Bacterial DNA was enriched from clinical urines (n = 10) and from healthy urines 'spiked' with multiresistant Escherichia coli (n = 5), then sequenced by MinION. Sequences were analysed using external databases and bioinformatic pipelines or, ultimately, using integrated real-time analysis applications. Results were compared with Illumina data and resistance phenotypes.

RESULTS

MinION correctly identified pathogens without culture and, among 55 acquired resistance genes detected in the cultivated bacteria by Illumina sequencing, 51 were found by MinION sequencing directly from the urines; with three of the four failures in an early run with low genome coverage. Resistance-conferring mutations and allelic variants were not reliably identified.

CONCLUSIONS

MinION sequencing comprehensively identified pathogens and acquired resistance genes from urine in a timeframe similar to PCR (4 h from sample to result). Bioinformatic pipeline optimization is needed to better detect resistances conferred by point mutations. Metagenomic-sequencing-based diagnosis will enable clinicians to adjust antimicrobial therapy before the second dose of a typical (i.e. every 8 h) antibiotic.

Predicting the development of acute kidney injury in liver cirrhosis--an analysis of glomerular filtration rate, proteinuria and kidney injury biomarkers

BACKGROUND

The timely diagnosis of acute kidney injury (AKI) in liver cirrhosis is challenging.

AIM

To evaluate whether quantification of glomerular filtration rate (GFR), proteinuria and kidney injury biomarkers can accurately predict the development of AKI.

METHODS

A prospective cohort analysis of patients with cirrhosis was performed. Measures of baseline kidney function included serum creatinine, iohexol clearance and urine protein:creatinine ratio. Blood and urine samples were collected daily. A retrospective analysis of cystatin C GFR and neutrophil gelatinase-associated lipocalin (NGAL) measured 48 h prior to the diagnosis of AKI was undertaken to evaluate their ability to predict the development of AKI.

RESULTS

Eighteen of the 34 cirrhosis patients studied developed AKI. A GFR <60 mL/min/1.73 m(2) was identified in 56% with Iohexol clearance compared to 8% using the four-variable modified diet in renal disease formula (P < 0.0001). Prediction of AKI, 48 h prior to the development of AKI with cystatin C GFR and serum NGAL concentration were similar; area under the receiver operating curve (AUROC) values 0.74 (0.51-0.97), P = 0.04 and 0.72 (0.52-0.92), P = 0.02 respectively. The development of AKI was strongly predicted by urine protein:creatinine ratio above the cut-off of >30 (equivalent to 300 mg/day of proteinuria) sensitivity 82% (57-96) and specificity 80% (52-96), AUROC 0.86 (0.73-0.98), P ≤ 0.0001. [OR 21 (3-133), P ≤ 0.002].

CONCLUSIONS

In patients with liver cirrhosis a urine protein:creatinine ratio >30 predicts AKI. Iohexol clearance and cystatin C formulae identify a greater proportion of patients with a GFR <60 mL/min/1.73 m(2), which also predicts the development of AKI.

Human liver regeneration is characterized by the coordinated expression of distinct microRNA governing cell cycle fate

In the absence of adequate compensatory regeneration, overwhelming liver damage can cause acute liver failure (ALF) and death without emergent liver transplantation (LT). Auxiliary LT produces satisfactory outcomes in this setting, with the prospect of native liver regeneration sustaining long-term survival. Since animal models only partially recapitulate human liver regeneration, we investigated the molecular mechanisms controlling it in this unique LT setting, as an exemplar of human liver regeneration. We demonstrate coordinated changes in expression of microRNA (miRNA) during regeneration that drive proliferation, innate immunity and angiogenesis. In contrast, failed regeneration in a similar cohort is associated with distinct miRNA enforcing cell cycle inhibition and DNA methylation. The miRNA expression associated with successful or failed regeneration when recapitulated in vitro, triggered expression of cardinal regeneration-linked genes promoting cell cycle entry or inhibition, respectively. Furthermore, inhibition of miRNA 150, 663 and 503, whose downregulation is associated with successful regeneration, induced cell proliferation which a key determinant of successful regeneration. Our data indicate that human liver regeneration may be orchestrated by distinct miRNA controlling key regeneration-linked processes including hepatocyte proliferation. To our knowledge this is the first characterization of molecular processes associated with human liver regeneration.

Genetic variation in DNMT3B and increased global DNA methylation is associated with suicide attempts in psychiatric patients

Recently, a significant epigenetic component in the pathology of suicide has been realized. Here we investigate candidate functional SNPs in epigenetic-regulatory genes, DNMT1 and DNMT3B, for association with suicide attempt (SA) among patients with co-existing psychiatric illness. In addition, global DNA methylation levels [5-methyl cytosine (5-mC%)] between SA and psychiatric controls were quantified using the Methylflash Methylated DNA Quantification Kit. DNA was obtained from blood of 79 suicide attempters and 80 non-attempters, assessed for DSM-IV Axis I disorders. Functional SNPs were selected for each gene (DNMT1; n = 7, DNMT3B; n = 10), and genotyped. A SNP (rs2424932) residing in the 3' UTR of the DNMT3B gene was associated with SA compared with a non-attempter control group (P = 0.001; Chi-squared test, Bonferroni adjusted P value = 0.02). Moreover, haplotype analysis identified a DNMT3B haplotype which differed between cases and controls, however this association did not hold after Bonferroni correction (P = 0.01, Bonferroni adjusted P value = 0.56). Global methylation analysis showed that psychiatric patients with a history of SA had significantly higher levels of global DNA methylation compared with controls (P = 0.018, Student's t-test). In conclusion, this is the first report investigating polymorphisms in DNMT genes and global DNA methylation quantification in SA risk. Preliminary findings suggest that allelic variability in DNMT3B may be relevant to the underlying diathesis for suicidal acts and our findings support the hypothesis that aberrant DNA methylation profiles may contribute to the biology of suicidal acts. Thus, analysis of global DNA hypermethylation in blood may represent a biomarker for increased SA risk in psychiatric patients.

Prediction models of donor arrest and graft utilization in liver transplantation from maastricht-3 donors after circulatory death

Shortage of organs for transplantation has led to the renewed interest in donation after circulatory-determination of death (DCDD). We conducted a retrospective analysis (2001-2009) and a subsequent prospective validation (2010) of liver Maastricht-Category-3-DCDD and donation-after-brain-death (DBD) offers to our program. Accepted and declined offers were compared. Accepted DCDD offers were divided into donors who went on to cardiac arrest and those who did not. Donors who arrested were divided into those producing grafts that were transplanted or remained unused. Descriptive comparisons and regression analyses were performed to assess predictor models of donor cardiac arrest and graft utilization. Variables from the multivariate analysis were prospectively validated. Of 1579 DCDD offers, 621 were accepted, and of these, 400 experienced cardiac arrest after withdrawal of support. Of these, 173 livers were transplanted. In the DCDD group, donor age < 40 years, use of inotropes and absence of gag/cough reflexes were predictors of cardiac arrest. Donor age >50 years, BMI >30, warm ischemia time >25 minutes, ITU stay >7 days and ALT ≥ 4× normal rates were risk factors for not using the graft. These variables had excellent sensitivity and specificity for the prediction of cardiac arrest (AUROC = 0.835) and graft use (AUROC = 0.748) in the 2010 prospective validation. These models can feasibly predict cardiac arrest in potential DCDDs and graft usability, helping to avoid unnecessary recoveries and healthcare expenditure.

Postpartum aHUS secondary to a genetic abnormality in factor H acquired through liver transplantation

We report here a young female who underwent a successful deceased donor liver transplant for hepatic vein thrombosis. Five years after transplantation she developed postpartum atypical hemolytic uremic syndrome (aHUS). She did not recover renal function. Mutation screening of complement genes in her DNA did not show any abnormality. Mutation screening of DNA available from the donor showed a nonsense CFH mutation leading to factor H deficiency. Genotyping of the patient showed that she was homozygous for an aHUS CD46 at-risk haplotype. In this individual, the development of aHUS has been facilitated by the combination of a trigger (pregnancy), an acquired rare genetic variant (CFH mutation) and a common susceptibility factor (CD46 haplotype).

New skeletal tuberculosis cases in past populations from Western Hungary (Transdanubia)

The distribution, antiquity and epidemiology of tuberculosis (TB) have previously been studied in osteoarchaeological material in the eastern part of Hungary, mainly on the Great Plain. The purpose of this study is to map the occurrence of skeletal TB in different centuries in the western part of Hungary, Transdanubia, and to present new cases we have found. Palaeopathological analysis was carried out using macroscopic observation supported by radiographic and molecular methods. A large human osteoarchaeological sample (n=5684) from Transdanubian archaeological sites ranging from the 2nd to the 18th centuries served as a source of material. Spinal TB was observed in seven individuals (in three specimens with Pott's disease two of which also had cold abscess) and hip TB was assumed in one case. The results of DNA for Mycobacterium tuberculosis were positive in seven of the eight cases identified by paleopathology, and negative in the assumed case of hip TB. However, the molecular results are consistent with highly fragmented DNA, which limited further analysis. Based on the present study and previously published cases, osteotuberculosis was found in Transdanubia mainly during the 9th-13th centuries. However, there are no signs of TB in many other 9th-13th century sites, even in those that lie geographically close to those where osteotuberculous cases were found. This may be due to a true absence of TB caused by the different living conditions, way of life, or origin of these populations. An alternative explanation is that TB was present in some individuals with no typical paleopathology, but that death occurred before skeletal morphological features could develop.

A simple, noninvasive test for the diagnosis of liver fibrosis in patients with hepatitis C recurrence after liver transplantation

Recurrent hepatitis C is a common cause of graft loss in patients undergoing liver transplantation, and serial protocol liver biopsies have been used to identify patients at risk of graft loss from rapid fibrosis progression. The aim of this study was to derive a simple noninvasive index to predict fibrosis in patients with recurrent hepatitis C post-transplant. A retrospective study was performed assessing serial liver biopsies for post-transplant chronic hepatitis C infection. One hundred eighty-five patients were included in the analysis; median age 53 years (interquartile range 48-59) and 140 (76%) were male. Liver histology showed 53 (29%) had Ishak fibrosis stages F0/F1, 31 (17%) had F2, 29 (16%) had F3, 19 (10%) had F4 and 53 (29%) had F5/F6. The London Transplant Centres' (LTC) score was derived combining aspartate aminotransferase (AST IU/L), time from liver transplant (TFLT months), international normalized ratio and platelets. Diagnostic accuracy of the LTC score was assessed using area under receiver-operating characteristic (ROC) curves. The area under the ROC curve for moderate fibrosis (F >or= 2) was 0.78 (95% CI, 0.70-0.86; P < 0.0001), for advanced fibrosis (F4-6) was 0.80 (95% CI, 0.72-0.87; P < 0.0001) and for cirrhosis was 0.80 (95% CI, 0.72-0.88; P < 0.0001). An optimal cut-off value of 6.3 distinguished patients with no or mild fibrosis (F <or= 1) odds ratio 10.8 (95% CI, 5.1-22.9); P < 0.0001), sensitivity 88%, specificity 60%, negative predictive value 67% and positive predictive value 84%. The LTC score can identify patients with Hepatitis C virus recurrence following liver transplant with a low risk of significant fibrosis, thus avoiding the need for protocol biopsy.

Osteonecrosis of the jaw complicating bisphosphonate treatment for bone disease in multiple myeloma: an overview with recommendations for prevention and treatment

Osteonecrosis of the Jaw (ONJ) is a recently recognised and potentially highly morbid complication of bisphosphonate therapy in the setting of metastatic malignancy, including myeloma. Members of the Medical and Scientific Advisory Group of the Myeloma Foundation of Australia formulated guidelines for the management of bisphosphonates around the issue of ONJ, based on the best available evidence in June 2008. Prior to commencement of therapy, patients should have an oral health assessment and be educated about the risks of ONJ. Dental assessment should occur 6 monthly during therapy. If tooth extraction is required, sufficient time should be allowed for complete healing to occur prior to commencement of bisphosphonate. As the risk of ONJ increases with duration of bisphosphonate therapy, we recommend annual assessment of dose with modification to 3 monthly i.v. therapy or to oral therapy with clodronate for those with all but the highest risk of skeletal-related event. Established ONJ should be managed conservatively; a bisphosphonate "drug holiday" is usually indicated and invasive surgery should generally be avoided. These recommendations will assist with clinical decision making for myeloma patients who are at risk of bisphosphonate-associated ONJ.

Selection of patients for liver transplantation and allocation of donated livers in the UK

BACKGROUND

The increasing shortfall between the number of patients who would benefit from liver transplantation and the availability of donor livers means that rationing has to occur. The processes of selection of patients for transplantation and for allocation of donor livers should be done according to ethical and, where possible, evidence-based criteria so that there is clarity and that the competing requirements of equity, justice, utility and benefit can be balanced.

METHODS

To achieve these goals for patients in the United Kingdom in need of transplantation, we have developed guidelines for the selection of patients to the national waiting list based on the risk of death without a transplant and the ability of the procedure to improve the recipient's quality of life. Guidelines have been developed for both those with acute liver failure and chronic liver disease. Allocation will depend on matching of the donor liver to the recipient.

RESULTS

The proposed system, to be introduced into the UK compares with some other systems, where different models for selection and allocation have been introduced.

The Glasgow alcoholic hepatitis score identifies patients who may benefit from corticosteroids

INTRODUCTION

There is no consensus on the pharmacological treatment of alcoholic hepatitis. The Glasgow alcoholic hepatitis score (GAHS) has been shown to be more accurate than the modified Maddrey's discriminant function (mDF) in the prediction of outcome from alcoholic hepatitis. This study aimed to determine whether the GAHS was able to identify those patients who would benefit from corticosteroids.

METHODS

225 patients with an mDF greater than or equal to 32 from five hospital centres in the United Kingdom were reviewed. Patient survival relative to the GAHS and the use of corticosteroids was recorded.

RESULTS

144 patients with an mDF greater than or equal to 32 (64%) also had a GAHS greater than or equal to 9. There was no difference in survival between untreated or corticosteroid-treated patients for those with a GAHS less than 9. For patients with a GAHS greater than or equal to 9 the 28-day survival for untreated and corticosteroid-treated patients was 52% and 78% (p = 0.002), and 84-day survival was 38% and 59% (p = 0.02), respectively.

CONCLUSIONS

Among patients with an mDF greater than or equal to 32, there was no appreciable benefit from treatment with corticosteroids in patients with a GAHS less than 9. Patients with a GAHS greater than or equal to 9 have an extremely poor prognosis if they are not treated with corticosteroids, or if such treatment is contraindicated.

The requirement for early exposure of Haemonchus contortus larvae to Bacillus thuringiensis for effective inhibition of larval development

The potential for a nematocidal Bacillus thuringiensis (Bt) to target the free-living larval stages of Haemonchus contortus was examined using in vitro larval development and migration assays. Bt toxicity in larval development assays decreased as the time period between egg hatch and initial exposure to the Bt was increased; a time lag of 48 h resulted in a 350-fold increase in the IC(50) (from 2.6 ng/ml to 910 ng/ml). The effects on larval migration largely paralleled the effects on larval development, indicating that the larvae which reached the infective stage after exposure to Bt were generally as 'fit' as control worms in terms of migration ability. However, a comparison of the two assays also showed the presence of a level of Bt exposure which showed significantly more toxicity in migration assays than development assays, indicating that, in some cases, fully developed Bt-exposed larvae were less able to migrate than controls, and hence may be compromised in their ability to infect sheep. The rapid decrease in toxicity when exposure to the Bt is delayed highlights a significant issue concerning the use of Bt for control of the free-living larval stages of animal-parasitic nematodes. Targeting the larvae by delivering bacterial spores to the faeces through the host animal's digestive tract would require the spores to germinate upon defecation, grow through a vegetative phase, to then produce crystal toxin protein upon subsequent sporulation. This period of bacterial development will introduce a time lag between worm egg hatching and initial exposure of the larvae to the Bt, which, as demonstrated in the present study, may allow the worm larvae to develop to late larval stages which are relatively insensitive to the toxin.

Artificial neural network is superior to MELD in predicting mortality of patients with end-stage liver disease

BACKGROUND

Despite its accuracy, the model for end-stage liver disease (MELD), currently adopted to determine the prognosis of patients with liver cirrhosis, guide referral to transplant programmes and prioritise the allocation of donor organs, fails to predict mortality in a considerable proportion of patients.

AIMS

To evaluate the possibility to better predict 3-month liver disease-related mortality of patients awaiting liver transplantation using an artificial neural network (ANN).

PATIENTS AND METHODS

The ANN was constructed using data from 251 consecutive people with cirrhosis listed for liver transplantation at the Liver Transplant Unit, Bologna, Italy. The ANN was trained to predict 3-month survival on 188 patients, tested on the remaining 63 (internal validation group) unknown by the system and finally on 137 patients listed for liver transplantation at the King's College Hospital, London, UK (external cohort). Predictions of survival obtained with ANN and MELD on the same datasets were compared using areas under receiver-operating characteristic (ROC) curves (AUC).

RESULTS

The ANN performed significantly better than MELD both in the internal validation group (AUC = 0.95 v 0.85; p = 0.032) and in the external cohort (AUC = 0.96 v 0.86; p = 0.044).

CONCLUSIONS

The ANN measured the mortality risk of patients with cirrhosis more accurately than MELD and could better prioritise liver transplant candidates, thus reducing mortality in the waiting list.

Organ transplantation in hereditary apolipoprotein AI amyloidosis

Patients with hereditary apolipoprotein AI (apoAI) amyloidosis often have extensive visceral amyloid deposits, and many develop end-stage renal failure as young adults. Solid organ transplantation to replace failing organ function in systemic amyloidosis is controversial due to the multisystem and progressive nature of the disease and the risk of recurrence of amyloid in the graft. We report the outcome of solid organ transplantation, including dual transplants in 4 cases, among 10 patients with apoAI amyloidosis who were followed for a median (range) of 16 (4-28) and 9 (0.2-27) years from diagnosis of amyloidosis and transplantation, respectively. Eight of 10 patients were alive, seven with a functioning graft at censor. Two patients died, one of disseminated cytomegalovirus infection 2 months after renal transplantation and the other of multisystem failure following severe trauma more than 13 years after renal transplantation. The renal transplant of one patient failed due to recurrence of amyloid after 25 years. Amyloid disease progression was very slow and the natural history of the condition was favorably altered in both cases in which the liver was transplanted. Failing organs in hereditary apoAI amyloidosis should be replaced since graft survival is excellent and confers substantial survival benefit.

Detection of UV-induced thymine dimers in individual Cryptosporidium parvum and Cryptosporidium hominis oocysts by immunofluorescence microscopy

To investigate the effect of UV light on Cryptosporidium parvum and Cryptosporidium hominis oocysts in vitro, we exposed intact oocysts to 4-, 10-, 20-, and 40-mJ x cm-2 doses of UV irradiation. Thymine dimers were detected by immunofluorescence microscopy using a monoclonal antibody against cyclobutyl thymine dimers (anti-TDmAb). Dimer-specific fluorescence within sporozoite nuclei was confirmed by colocalization with the nuclear fluorogen 4',6'-diamidino-2-phenylindole (DAPI). Oocyst walls were visualized using either commercial fluorescein isothiocyanate-labeled anti-Cryptosporidium oocyst antibodies (FITC-CmAb) or Texas Red-labeled anti-Cryptosporidium oocyst antibodies (TR-CmAb). The use of FITC-CmAb interfered with TD detection at doses below 40 mJ x cm-2. With the combination of anti-TDmAb, TR-CmAb, and DAPI, dimer-specific fluorescence was detected in sporozoite nuclei within oocysts exposed to 10 to 40 mJ x cm-2 of UV light. Similar results were obtained with C. hominis. C. parvum oocysts exposed to 10 to 40 mJ x cm-2 of UV light failed to infect neonatal mice, confirming that results of our anti-TD immunofluorescence assay paralleled the outcomes of our neonatal mouse infectivity assay. These results suggest that our immunofluorescence assay is suitable for detecting DNA damage in C. parvum and C. hominis oocysts induced following exposure to UV light.

Skin lesions in adult liver transplant recipients: a study of 100 consecutive patients

BACKGROUND

The surgical advances made in the area of organ transplantation along with the use of more efficacious immunosuppression have meant an increase in patient survival. This longer-living transplant population has started to exhibit cutaneous problems, some of which lead to an increased mortality while others lead to a decline in the quality of life.

OBJECTIVES

The primary objective was to determine the different types of cutaneous lesions encountered in the adult liver transplant population. Secondary objectives were to determine the impact, if any, of the duration of transplant, the type of immunosuppression involved and the degree of sun exposure and skin phototype, on the skin cancers encountered in this transplanted population.

METHODS

Two dermatologists examined 100 consecutive liver transplant recipients (LTRs) attending the transplant outpatient department. Skin examination included the face and whole body and lesions found were categorized into the following groups: cutaneous malignancies, squamoproliferative lesions, cutaneous infections and others that did not fall into any of these categories.

RESULTS

The reasons for organ transplantation were numerous. The mean age at transplantation was 42.5 years. The average time since transplantation was 5.5 (range 0.75-16 years). Four patients developed skin cancers; among them there were a total of seven skin cancers (one squamous cell carcinoma, six basal cell carcinomas). Fungal infections accounted for 19% of all cutaneous infections seen, viral infections 2% and bacterial infections 5%. Triple-drug immunosuppressive therapy (ciclosporin A, azathioprine and prednisolone) was used in 35% of LTR patients, while dual therapy (tacrolimus and prednisolone) was used in 48% and monotherapy (tacrolimus) was used in 17% of LTRs.

CONCLUSIONS

Immunosuppressive therapy is believed to be one of the most important risk factors in the development of skin cancer in solid organ transplant recipients. The relatively low prevalence of skin cancer in our liver transplant population may in part be explained by the relatively high percentage of recipients on dual and monotherapy (48% and 17% respectively), and the shorter duration of therapy. Our study suggests that although LTRs are at higher risk of developing nonmelanoma skin cancer than the general population, the risk is comparable with other solid organ transplant recipients.

Cryptosporidium parvum sporozoites contain glutathione

We used the fluorescent dye monochlorobimane (MCB) which binds glutathione (GSH) to localize between 2 and 6 distinctly labelled nuclear and cytoplasmic GSH foci in recently excreted and aged, intact Cryptosporidium parvum oocysts and sporozoites. Buthionine sulfoximine (BSO), a potent and specific inhibitor of GSH, was used to determine whether GSH is synthesized in BSO-treated C. parvum oocysts, by labelling treated oocysts with MCB. Both visual and electronic quantifications were performed. At 5 mM BSO, a significant inhibition of MCB fluorescence, reflecting reduced MCB uptake, was observed in GSH-depleted oocysts (mean +/- S.D. 35 +/- 3.7) compared with controls (3.3 +/- 1.2, P = 0). This clear reduction occurred only in viable oocysts. 1 mM BSO-treated oocysts exhibited weak or no MCB fluorescence, although they were viable (excluded propidium iodide, PI)), and intact and contained sporozoites by differential interference contrast microscopy (DIC). MCB was used in conjunction with PI to determine C. parvum oocyst viability. Oocysts labelled with MCB/PI or 4'6-diamidino-2-phenyl indole (DAPI)/PI produced comparable labelling patterns. Viable oocysts were labelled with MCB or DAPI whereas dead oocysts were labelled with PI only. The localization of GSH in viable, intact oocysts and excysted sporozoites and UV light-irradiated oocysts and sporozoites revealed no changes in MCB uptake at levels up to 40 mJ.cm(-2) irradiation. Although GSH can be detected following MCB localization in both the nucleus and cytoplasm of sporozoites, and can be specifically depleted by BSO treatment, MCB is unlikely to be useful as a surrogate for detecting UV damage in UV-treated Cryptosporidium oocysts.

Personal view: current role of artificial liver support devices

Enthusiasm for liver support devices, particularly cell-based biological systems and albumin dialysis, increased over the last decade and there has been considerable clinical activity both within and without the construct of clinical trials. Most data have been generated on patients with acute liver failure or in patients with decompensation of chronic liver disease, often referred to as acute-on-chronic liver failure. In acute liver failure liver, liver support devices are more realistically being used as a 'bridge' to liver transplantation rather than to transplant-free survival. In acute-on-chronic liver failure the clinical objective of attaining clinical stability with treatment appears more achievable. The so-called bioartificial liver device, based on porcine hepatocytes, is the most extensively evaluated biological device. A sizeable clinical trial failed to demonstrate efficacy, but secondary analyses suggest it would be unwise to assume futility had been established with this device. Molecular adsorbent recirculating system leads the way in the non-biological category in terms of the number of patients treated, but data from large clinical trials are not yet available. One of the strongest conclusions of this review is that the amount of high-quality data available on liver support devices dramatically understates the effort and money that have been expended in their assessment. It is very clear that randomized controlled trials are mandatory to establish clinical efficacy, but it is less clear how the ideal trial should be constructed.

A modified larval migration assay for detection of resistance to macrocyclic lactones in Haemonchus contortus, and drug screening with Trichostrongylidae parasites

We have developed a modified migration assay system in 96-well plate format which is able to detect resistance to the macrocyclic lactone group of drugs in Haemonchus contortus. The assay involves exposure of infective stage larvae to drug for a 24 h period, then counting the numbers of larvae that are able to migrate through an agar and filter mesh system over a further 48 h. The agar barrier greatly increased the sensitivity of the assay for resistance detection compared to use of filter mesh alone. The assay was able to detect the presence of 10% resistant worms in an otherwise susceptible background. However, the assay was ineffective with Trichostrongylus colubriformis and Ostertagia circumcincta indicating that its usefulness for field monitoring will be restricted to situations where H. contortus is of most significance. A small-scale drug screening exercise showed that the assay identifies some anthelmintic activities distinct from those identified by larval development assays. The assay therefore also has a potential role in drug discovery programmes in screening for new anthelmintics.

Toxicity of Bacillus thuringiensis to parasitic and free-living life-stages of nematode parasites of livestock

A collection of Bacillus thuringiensis (Bt) strains (Bts) were screened for activity against the free-living larval stages of nematode parasites of livestock. Two strains were identified with significant activity in inhibiting larval development of Haemonchus contortus, Trichostrongylus colubriformis and Ostertagia circumcincta. These strains were also toxic to the adult parasitic stages of these nematode species in vitro. Adult H. contortus and O. circumcincta showed complete cessation of movement within 2 and 4 days, respectively. Trichostrongylus colubriformis adults were less affected, however, movement was still significantly reduced compared with controls. The in vitro activity against the larval stages was of a magnitude similar to or greater than that seen with the anthelmintic drugs thiabendazole and levamisole. N-terminal amino acid sequencing indicated that the two Bts contained either Cry5A and Cry5B proteins, or a Cry13 protein, and the presence of the corresponding cry5A, cry5B and cry13 genes was confirmed by PCR and sequencing. Bacillus thuringiensis spore-crystal suspensions exposed to acidic pH conditions (pH<or=3) showed greatly reduced toxicity in subsequent bioassays with nematode larvae, highlighting the need to protect the toxin from the acidic conditions of the sheep abomasum if it were to be administered per os as an anthelmintic. This study indicates that both the parasitic adult stages and the free-living larval stages of economically significant nematode parasites are susceptible to the effects of Bt, thus identifying this group of toxins as potential biocontrol agents.

Analysis of factors predictive of mortality in alcoholic hepatitis and derivation and validation of the Glasgow alcoholic hepatitis score

INTRODUCTION

Alcoholic hepatitis is associated with a high short term mortality. We aimed to identify those factors associated with mortality and define a simple score which would predict outcome in our population.

METHODS

We identified 241 patients with alcoholic hepatitis. Clinical and laboratory data were recorded on the day of admission (day 1) and on days 6-9. Stepwise logistic regression was used to identify variables related to outcome at 28 days and 84 days after admission. These variables were included in the Glasgow alcoholic hepatitis score (GAHS) and its ability to predict outcome assessed. The GAHS was validated in a separate dataset of 195 patients.

RESULTS

The GAHS was derived from five variables independently associated with outcome: age (p = 0.001) and, from day 1 results, serum bilirubin (p<0.001), blood urea (p = 0.019) and, from day 6-9 results, serum bilirubin (p<0.001), prothrombin time (p = 0.002), and peripheral blood white blood cell count (p = 0.001). The GAHS on day 1 had an overall accuracy of 81% when predicting 28 day outcome. In contrast, the modified discriminant function had an overall accuracy of 49%. Similar results were found using information at 6-9 days and when predicting 84 day outcome. The accuracy of the GAHS was confirmed by the validation study of 195 patients The GAHS was equally accurate irrespective of the use of the international normalised ratio or prothrombin time ratio, or if the diagnosis of alcoholic hepatitis was biopsy proven or on the basis of clinical assessment.

CONCLUSIONS

Using variables associated with mortality we have derived and validated an accurate scoring system to assess outcome in alcoholic hepatitis. This score was able to identify patients at greatest risk of death throughout their admission.

Glial fibrillary acidic protein mRNA levels in the cingulate cortex of individuals with depression, bipolar disorder and schizophrenia

Recent studies have shown a decrease in glial number and glial fibrillary acidic protein (GFAP) levels in the frontal and cingulate cortices of individuals with mood disorders and schizophrenia. In an attempt to verify and expand these findings we examined GFAP messenger ribonucleic acid (mRNA) levels in postmortem sections of the anterior cingulate cortex (ACC) from the Stanley Neuropathology Consortium (SNC). The consortium consists of 15 cases in each of four groups (schizophrenia, bipolar disorder, non-psychotic depression and unaffected controls). By in situ hybridization, we found higher levels of GFAP mRNA in white matter and at the pial surface as compared with gray matter levels in all cases. In the white matter of ACC we detected a significant effect of diagnosis (P<0.04) with GFAP mRNA levels decreased in individuals with schizophrenia and bipolar disorder as compared with normal controls. In the gray matter there was a significant effect of layer (P<0.01) with the highest levels of GFAP mRNA in layer VI in all groups. As in the white matter, the mean GFAP mRNA levels were decreased in individuals with schizophrenia and bipolar disorder as compared with the unaffected controls, however the difference failed to reach statistical significance. Thus, astrocytes positive for GFAP may contribute to the decrease in glial density previously described in subjects with major mental illness, however the relative contribution of astrocytes may vary with diagnosis.

An in vitro larval motility assay to determine anthelmintic sensitivity for human hookworm and Strongyloides species

With the implementation of programs to control lymphatic filariasis and soil-transmitted helminths using broad spectrum anthelmintics, including albendazole and ivermectin, there is a need to develop an in vitro assay for detection of drug resistance. This report describes an in vitro assay for measuring the effects of ivermectin and benzimidazoles on the motility of larvae of the hookworm species Ancylostoma ceylanicum, A. caninum, and Necator americanus, and Strongyloides species including Strongyloides stercoralis, and S. ratti. A dose-response relationship was demonstrated with each of the parasite species, with distinct differences observed between the various species. In pilot field testing of the assay with N. americanus larvae recovered from human fecal samples, a dose-response relationship was observed with ivermectin. While the assay has demonstrated the ability to determine drug responsiveness, its usefulness in resistance detection will require correlation with the clinical outcome among individuals infected with parasite strains showing different drug sensitivities.

Haemonchus contortus: in vitro drug screening assays with the adult life stage

Motility and feeding assays were assessed as in vitro systems for screening of novel compounds for anthelmintic activity against adult Haemonchus contortus. The study aimed to develop an assay with the parasitic adult stage of this species that could be used in conjunction with, or as an alternative to, the free-living larval stage screens commonly used for drug discovery with many parasitic nematode species. The feeding assay showed limitations due to the apparent continuation of a significant degree of feeding in worms showing greatly reduced motility in the presence of some drugs. Hence, it appeared most likely that the feeding assay would underestimate the toxicity of these drugs. The motility assay was able to detect toxicity of known anthelmintics, including the 'slow-acting' benzimidazoles. A small-scale screening exercise used the motility assay to detect toxicity towards adult parasites in 10 compounds out of a group of 200 chemicals (selected due to known toxic effects in larval development assays). The motility assay appeared suitable for drug screening against adult H. contortus. The use of the adult stage for drug screening in this way ensures that the drug is toxic towards the parasite life stage to be targeted in vivo. A lack of activity in subsequent in vivo trials could, therefore, be most likely attributable to host pharmacokinetic factors rather than an intrinsic lack of activity of the drug towards the adult parasite.

Hepatitis C among drug users: consensus guidelines on management in general practice

BACKGROUND

Hepatitis C (HCV) is a common cause of morbidity among patients who attend general practitioners (GPs) in Ireland for methadone maintenance treatment.

AIMS

To describe the development and content of guidelines for the management of HCV among current or former opiate users in the Eastern Regional Health Authority area attending GPs for methadone treatment.

METHODS

The guidelines were produced in five stages: identification of key stakeholders; development of evidence-based draft guidelines; discussion of content; determination of 'Delphi'-facilitated consensus and review by a sample of GPs for whom the guidelines would be intended.

RESULTS

The guidelines contain advice for GPs on all aspects of care of patients at risk of HCV, including general and preventative care, care of other bloodborne and hepatotoxic viruses, and the factors to be considered and appropriate evaluation prior to referring a patient for assessment at a hepatology unit.

CONCLUSIONS

GPs have an important role to play in the care of patients at risk of, or infected with, HCV.

Professional athletes suffering from familial hypercholesterolaemia rarely tolerate statin treatment because of muscular problems

AIMS

Muscular problems are the major group of side-effects during statin treatment. They are known to occur much more frequently during and after exercise.

METHODS AND RESULTS

For the last 8 years we have monitored 22 professional athletes in whom, because of familial hypercholesterolaemia, treatment with different statins was attempted. Only six out of the 22 finally tolerated at least one member of this family of drugs. In three of these six the first statin prescribed allowed training performance without any limitation. Changing the drug demonstrated that only two tolerated all the four or five statins examined (atorvastatin, fluvastatin, lovastatin, pravastatin, simvastatin). Cerivastatin was not among the statins prescribed.

CONCLUSIONS

These findings indicate that in top sports performers only about 20% tolerate statin treatment without side-effects. Clinical decision making as to lipid lowering therapy thus becomes a critical issue in this small subgroup of patients.

Professional athletes suffering from familial hypercholesterolaemia rarely tolerate statin treatment because of muscular problems

AIMS

Muscular problems are the major group of side-effects during statin treatment. They are known to occur much more frequently during and after exercise.

METHODS AND RESULTS

For the last 8 years we have monitored 22 professional athletes in whom, because of familial hypercholesterolaemia, treatment with different statins was attempted. Only six out of the 22 finally tolerated at least one member of this family of drugs. In three of these six the first statin prescribed allowed training performance without any limitation. Changing the drug demonstrated that only two tolerated all the four or five statins examined (atorvastatin, fluvastatin, lovastatin, pravastatin, simvastatin). Cerivastatin was not among the statins prescribed.

CONCLUSIONS

These findings indicate that in top sports performers only about 20% tolerate statin treatment without side-effects. Clinical decision making as to lipid lowering therapy thus becomes a critical issue in this small subgroup of patients.

Regional specificity of brain glucocorticoid receptor mRNA alterations in subjects with schizophrenia and mood disorders

Glucocorticoid receptors (GR) mediate the direct effects of glucocorticoids released in response to stress and the regulation of the hypothalamic-pituitary-adrenocortical (HPA) system through a negative feedback mechanism. Individuals with major mental illness, who often exhibit hypercortisolemia, may have down-regulated levels of GR mRNA. In situ hybridization for GR mRNA was performed on post-mortem specimens from patients suffering from depression, bipolar disorder, schizophrenia and from normal controls (n = 15 per group). In frontal cortex, GR mRNA levels were decreased in layers III-VI in the subjects with depression and schizophrenia. In inferior temporal cortex, GR mRNA levels were decreased in layer IV in all three diagnostic groups. In the entorhinal cortex, GR mRNA levels were decreased in layers III and VI in the bipolar group. In hippocampus, GR mRNA levels were reduced in the dentate gyrus, CA(4), CA(3) and CA(1) in the schizophrenia group. In the subiculum, GR mRNA levels were reduced in the bipolar group. These results suggest that GR dysregulation occurs in all three major psychiatric illnesses with variability according to anatomical site. The severity and heterogeneity of this reduction may underlie some of the clinical heterogeneity seen in these disorders.

Phase II study of the efficacy and safety of cisplatin-epinephrine injectable gel administered to patients with unresectable hepatocellular carcinoma

PURPOSE

To study the efficacy and safety of percutaneous cisplatin-epinephrine (CDDP-EPI) injectable gel in patients with localized unresectable hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Eligible patients had histologically proven HCC, no prior treatment except for surgery, and no more than three tumors (each measured < or = 7 cm, total tumor volume < or = 200 cm(3)). They were treated percutaneously under ultrasound or computed tomography (CT) guidance, with up to 10 mL of CDDP-EPI gel (1 mL contains 4 mg of CDDP and 0.1 mg of EPI) per treatment and four treatments in 6 weeks to a maximum of eight treatments. The primary end points were tumor response, defined by change of percentage of tumor necrosis according to CT criteria, and safety. Survival parameters were secondary end points.

RESULTS

From June 1997 to April 2000, 58 patients (median age, 65 years) entered the study. All patients were assessable for safety, and 51 were assessable for efficacy. The median number of treatments was four (range, one to eight treatments). Objective response rate was 53% (27 of 51 patients), including 16 complete and 11 partial responses. Of the 27 responders, 14 (52%) subsequently developed progressive disease, but in most of them (93%), a new tumor arose at untreated liver sites. Median survival was 27 months (range, 18.4 to 35.7 months). The 1-, 2-, and 3-year survival rates were 79%, 56%, and 14% respectively. The procedure was well tolerated with only minor side effects.

CONCLUSION

Percutaneous local ablation with CDDP-EPI injectable gel can induce significant tumor necrosis and local control for localized unresectable HCC, and the treatment is well tolerated.

Assessment of portal venous system patency in the liver transplant candidate: a prospective study comparing ultrasound, microbubble-enhanced colour Doppler ultrasound, with arteriography and surgery

AIM

To determine the role of microbubble-enhanced colour Doppler ultrasound (CDUS) in assessing portal venous patency prior to liver transplantation.

MATERIALS AND METHODS

Over a 2-year period, all patients with chronic liver disease undergoing routine pre-transplant CDUS examination in whom the portal venous system was inadequately demonstrated were recruited to the study. CDUS was performed in 368 patients and 33 patients (9%) were recruited. A repeat CDUS examination following an intravenous bolus injection of the microbubble contrast agent Levovist (Schering Healthcare AG, Berlin, Germany) was performed. Diagnostic confidence was recorded on a free linear analogue scale for both examinations. Findings were compared with indirect portography and surgery.

RESULTS

Of the 33 patients with sub-optimal baseline examinations, improvement in portal vein visualization was achieved in 31 patients (94%). Median diagnostic confidence increased from 50% (interquartile range 30-60) to 90% (interquartile range 75-98) (P < 0.001) following administration of Levovist. Overall accuracy of portal vein assessment using microbubble-enhanced CDUS in 15 patients in whom a definitive diagnosis was made within 2 months was 87%.

CONCLUSION

Microbubble-enhanced CDUS is a simple, inexpensive adjunct to standard pre liver transplant screening of the portal vein. It is particularly helpful in patients with end-stage cirrhosis who are at high risk of portal vein thrombosis and in whom the conventional examination is sub-optimal.

Liver transplantation in adults coinfected with HIV

OBJECTIVE

To report our experience of prospectively identifying and transplanting livers into HIV-positive patients.

DESIGN

Liver transplantation in HIV-positive patients remains controversial. The finding of HIV is usually considered a contraindication to any form of transplantation. Previously reported cases are few and refer to patients who tested HIV positive after they had their liver transplantations or who seroconverted in the posttransplantation period. This is, to our knowledge, the only report of patients who were known to be HIV positive at the time of decision for listing for transplantation.

METHODS

The medical records of five HIV-positive patients who received liver transplants in King's College Hospital, London, during a 5-year period (January 1995-December 1999) were reviewed. All five were known to be HIV positive at the time of listing for liver replacement. Three of them had end-stage liver disease due to hepatitis C (two of them had underlying Hemophilia A) while the other two had acute liver failure, one due to hepatitis B infection and one due to nonA-nonB-nonC hepatitis. In all but one patient the HIV infection had been asymptomatic.

RESULTS

All patients survived the immediate posttransplantation period, but the three patients with hepatitis C died of complications of recurrent hepatitis C between 6 and 25 months posttransplantation. The other two patients are currently alive 4 and 34 months posttransplantation with good graft function and without complications from their HIV infection.

CONCLUSION

The early outcome of liver transplantation in HIV seropositive patients can be good, and patients should not be excluded from transplantation if their liver disease determines their prognosis. More effective antiviral therapy for hepatitis C given posttransplantation, and for hepatitis B reinfection, should improve the longer-term outcome of HIV patients with end-stage liver disease due to hepatitis.

Pharmacokinetics and absolute bioavailability of sitafloxacin, a new fluoroquinolone antibiotic, in healthy male and female Caucasian subjects

1. The aim was to compare the pharmacokinetics of sitafloxacin from a capsule formulation (dose of 500 mg sitafloxacin) and an intravenous (i.v.) formulation infused over 1 h (dose of 400 mg sitafloxacin) in healthy male and female subjects and to estimate the absolute bioavailability of sitafloxacin from the capsule formulation. 2. Following oral administration, sitafloxacin was rapidly absorbed, with a mean maximum concentration in plasma of 4.65 microgml(-1) occuring at median tmax = 1.25 h giving a mean AUC(0-infinity) = 28.1 microg h ml(-1). For the i.v. administration, a mean Cmax = 5.53 microm(-1) occurred at the end of the 1-h infusion with a mean AUC(0-infinity) = 25.4 microg h ml(-1). The mean terminal elimination half-life was 7.0 h (oral) and 6.6 h (i.v.). For the oral and i.v. formulations, the mean total plasma clearance was 296 and 263 mlmin(-1), respectively and the mean volume of distribution was 180 and 150 litres, respectively. 3. Within 48 h post-dose, approximately 61% (range 22-86%) of the administered dose was excreted unchanged in urine following capsule administration, compared with approximately 75% (range 42-101%) following the i.v. formulation. For both formulations, the renal clearance of sitafloxacin (means of 181 and 198 ml min(-1) for the capsule and i.v. doses, respectively) implies active tubular secretion of the drug. 4. The absolute bioavailability of sitafloxacin from the capsule formulation was high at 89%, with a 95% CI of 84-94%. The intersubject variability (CV%) in the sitafloxacin AUC(0-infinity) for the capsule was low at 18.6%. 5. Gender differences in the pharmacokinetics of sitafloxacin were small and would not warrant dose adjustment. 6. The findings show that the capsule formulation offers good oral bioavailability and merits further clinical evaluation of sitafloxacin as an orally effective fluoroquinolone antibacterial.