Polyethylene Wear in Retrieved Canine Acetabular Components

The aim of this pilot study was to define the mechanism and mode of polyethylene wear in acetabular components retrieved from seven dogs following therapeutic total hip replacement. The articular surface of each acetabular component was examined using contact profilometry and scanning electron microscopy (SEM). Peak-tovalley distance (P-V) and arithmetic average surface roughness (Ra) were calculated for each quadrant of the surface. Deformation of the regular profile of the machining lines was the least severe form of surface alteration. Randomly orientated scratches, fine tapered filaments, ripples, and coarse surface shredding were common SEM observations. Gouging of the convex surface of the cup was seen in two cases following failure of the polyethylenecement interface. Wear of the nonarticular acetabular rim suggested neck impingement in one case. P-V and Ra were significantly lower in the craniodorsal zone, compared to the average roughness of the other three quadrants (p < 0.05). Abrasion, adhesion and fatigue were the principal mechanisms of polyethylene wear, and were implicated in the production of polyethylene particulate debris. Meticulous removal of abrasive third bodies at the time of surgery, and correct orientation of the acetabular component, should reduce early and severe wear.

Polyethylene wear is inevitable following metal-on-polyethylene total hip replacement. In this study, the nature of polyethylene wear in retrieved canine acetabular components was defined, using contact profilometry and scanning electron microscopy. Abrasion, adhesion and fatigue were the principal mechanisms of wear, and were implicated in the production of polyethylene particulate debris.

Is there an opportunity to reduce urinary catheter-related infections? Exploring variation in catheterisation rates in care homes

rinary catheterisation in care homes is associated with increased morbidity, hospitalisation and mortality. The authors aimed to determine whether staffing, resident underlying illness or nursing band, or use of other toileting methods were responsible for the wide variation in urinary catheterisation rates found in English care homes. The authors approached randomly-selected registered care homes in three former health districts in England. A questionnaire survey was used to determine the number of residents in each nursing care band and with different medical conditions that were catheterised, and the home's management of residents' continence. The number of residents or staffing did not influence catheterisation rate. Higher catheterisation rate homes had a lower proportion of high band nursing residents and residents with incontinence, severe physical disability and dementia than the other homes. Only urinary retention (3 per cent of residents) was significantly more common in the higher catheterisation rate homes. There was no difference in continence care before inserting a catheter. The authors suggest that care culture and staff attitudes to catheterisation should be explored in greater depth using structured interviews or focus groups. This may allow the identification of key factors that can be targeted in order to reduce catheterisation rates and the associated morbidity.

The longitudinal prevalence of MRSA in care home residents and the effectiveness of improving infection prevention knowledge and practice on colonisation using a stepped wedge study design

Objectives To determine the prevalence and health outcomes of meticillin-resistant Staphylococcus aureus (MRSA) colonisation in elderly care home residents. To measure the effectiveness of improving infection prevention knowledge and practice on MRSA prevalence. Setting Care homes for elderly residents in Leeds, UK. Participants Residents able to give informed consent. Design A controlled intervention study, using a stepped wedge design, comprising 65 homes divided into three groups. Baseline MRSA prevalence was determined by screening the nares of residents (n=2492). An intervention based upon staff education and training on hand hygiene was delivered at three different times according to group number. Scores for three assessment methods, an audit of hand hygiene facilities, staff hand hygiene observations and an educational questionnaire, were collected before and after the intervention. After each group of homes received the intervention, all participants were screened for MRSA nasal colonisation. In total, four surveys took place between November 2006 and February 2009. Results MRSA prevalence was 20%, 19%, 22% and 21% in each survey, respectively. There was a significant improvement in scores for all three assessment methods post-intervention (p≤0.001). The intervention was associated with a small but significant increase in MRSA prevalence (p=0.023). MRSA colonisation was associated with previous and subsequent MRSA infection but was not significantly associated with subsequent hospitalisation or mortality. Conclusions The intervention did not result in a decrease in the prevalence of MRSA colonisation in care home residents. Additional measures will be required to reduce endemic MRSA colonisation in care homes.

Comparative analysis of prevalence, risk factors, and molecular epidemiology of antibiotic-associated diarrhea due to Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus

We prospectively studied the comparative epidemiology and risk factors for Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus antibiotic-associated diarrhea (AAD). Four thousand six hundred fifty-nine inpatient fecal specimens (11 months) were tested for C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus by Vero cell assay, enzyme-linked immunosorbent assay, and growth on fresh blood agar, respectively. Two distinct age-, sex-, and location-matched control patient groups were used for multivariate logistic regression risk factor analyses: symptomatic patients who were AAD pathogen negative and asymptomatic patients with histories of recent antimicrobial therapy. All AAD pathogen isolates were DNA fingerprinted. In AAD cases, the prevalences of C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus were 12.7%, 3.3%, and 0.2%, respectively (15.8% overall). Age of >70 years was a common risk factor. Other risk factors for infective AAD and C. difficile AAD included length of hospital stay and use of feeding tubes (length of stay odds ratios [OR], 1.017 and 1.012; feeding tube OR, 1.864 and 2.808). Female gender and use of antacids were significantly associated with increased risk of C. perfringens AAD (OR, 2.08 and 2.789, respectively), but unlike what was found for C. difficile AAD, specific antibiotic classes were not associated with increased risk. A limited number of genotypes caused the majority of C. difficile and C. perfringens AAD cases. Similar to what was found for C. difficile AAD, there was epidemiological evidence of C. perfringens AAD case clustering and reinfection due to different strains. C. difficile AAD was approximately 4 and 60 times more common than C. perfringens AAD and S. aureus AAD, respectively. Risk factors for these AAD pathogens differed, highlighting the need to define specific control measures. There is evidence of nosocomial transmission in cases of C. perfringens AAD.

Why does Japan have a high incidence of gastric cancer? Comparison of gastritis between UK and Japanese patients

BACKGROUND AND AIMS

The incidence of gastric cancer in Japan is four times higher than in the UK. It usually arises in a stomach with corpus predominant or pangastritis that has undergone extensive atrophy and intestinal metaplasia. We hypothesised that a Japanese population would have a more severe gastritis with a corpus predominant or pangastritis pattern and a greater degree of atrophy and intestinal metaplasia than that found in the UK. To test this we designed a comparative trial.

METHODS

A total of 252 age matched consecutive patients were recruited from the endoscopy services in Leeds and Tokyo. In each centre, 21 patients were prospectively selected from each decennial, between the ages of 20-80 years. All had epigastric discomfort as their predominant symptom. Patients with peptic ulcer, cancer, and oesophagitis were excluded. Five gastric biopsies were examined by two histopathologists using the updated Sydney system. Helicobacter pylori infection was assessed by histology and culture of biopsies and enzyme linked immunosorbent assay and immunoblot of plasma.

RESULTS

Gastritis was found by both pathologists in 59 (47%) UK and 76 (60%) Japanese patients (chi(2) test, p = 0.04). In those patients with gastritis, corpus predominant or pangastritis was commoner in the Japanese (63% Japan v 36% in the UK (chi(2) test, p = 0.003) Atrophy and intestinal metaplasia were more extensive and severe (Mann-Whitney U test, p<0.001) and chronic inflammation and polymorph activity were also greater, especially in the corpus (Mann-Whitney U test, p<0.001). Fifty three of 59 UK gastritis patients (90%) and 67/76 (88%) (chi(2) test, p = 1) Japanese gastritis patients were positive for H pylori. Using a previously described "gastric cancer risk index" among H pylori positive patients, there were significantly more Japanese than UK subjects with a "high risk" score.

CONCLUSION

In Japanese as opposed to English patients, gastritis is more prevalent and severe with more corpus predominant atrophy and intestinal metaplasia. These differences may partially explain the higher incidence of gastric cancer in Japan.

Urinary catheterization in care homes for older people: self-reported questionnaire audit of catheter management by care home staff

A self-administered questionnaire was used to determine care home staff's reported knowledge of the urinary catheter care standards published by the National Institute for Clinical Excellence (NICE) and the Association of Continence Care, and to see whether this differed in homes with higher catheterization rates. Seven hundred and fifty out of 1438 (52%) nursing and care staff from 37 randomly selected care homes with high, medium and low catheterization rates responded. There was no difference in reported practice in care homes in the three health districts sampled or those with differing catheterization rates. Eighty-three percent of the nursing staff and 40% of the other care staff received formal catheter care training. However, at least 10% of all staff reported not washing their hands before handling a catheter, and delaying emptying a urine bag until it was full, rather than three-quarters full. Only 45% of nursing staff and 40% of other care staff encouraged residents to empty their own catheter bags. Routine use of catheter maintenance solutions or bladder washouts was reported by 50% of all staff. Nursing staff (29%) and other care staff (54%) took urine specimens from the catheter bag tap. Compliance with standards has improved greatly since an audit in 1998. However, some non-compliance remains. There is a need for ongoing local audit and formal training in urinary catheter care, particularly for non-qualified care staff. Education is needed to ensure local implementation of NICE guidance.

Prevalence of urinary catheterization in UK nursing homes

A postal questionnaire survey was undertaken in registered nursing homes in three different health districts in England: Gloucestershire, North Staffordshire and Leeds. Nursing homes may be registered as general nursing or mental health homes. If homes also have provision for residential beds these are defined as dual registered homes. Overall, 9% (438/4900) of residents, with an equal male:female split, had urinary catheters. There was no significant difference in the overall urinary catheterization rate in the three districts (P=0.9). There was a wide range of urinary catheterization prevalence between homes, with some homes of all three categories having no catheterized residents and several with a prevalence of over 40%. The wide range of prevalence may be due to differences in residents' underlying medical conditions or to differences in attitudes towards urinary catheterization by nursing home staff. Almost all homes (114/124, 92%) stated they had an infection control policy, but 31% (38/124) did not have a written policy on urinary catheter care. In view of the potential for morbidity, infection control policies should include a section on the care of urinary catheters and this should form part of the continuing training of nursing home staff.

Characterisation of strains of enteroaggregative Escherichia coli isolated during the infectious intestinal disease study in England

Strains of Escherichia coli, hybridising with a DNA probe for enteroaggregative E. coli (EAggEC), were isolated from patients with infectious intestinal disease (IID) or gastro-enteritis, and healthy controls during the study of IID in England. Of 3506 cases presenting with an IID, 160 (4.6%) had faecal EAggEC as compared with 46 (1.7%) of 2772 healthy controls, 53% of EAggEC isolated from each of the 'case' and the 'control' groups adhered in a 'stacked-brick' formation. Strains from cases and controls belonged to over 39 and 14 different serogroups respectively, and approximately half of the strains isolated did not react with antisera in the current somatic antigen serotyping scheme. Forty-nine cases with EAggEC (31%) had a known history of foreign travel. Over 50% of strains isolated from cases and controls were resistant to one or more of eight antimicrobials, and antimicrobial resistance was not statistically significantly more common among cases with a known history of foreign travel (p = 0.57). These data form part of the largest investigation carried out on these organisms in the UK to date and provide the most comprehensive analysis of strains of EAggEC isolated from the general population of England.

The optimal antibiotic combination in a 5-day Helicobacter pylori eradication regimen

BACKGROUND

Current guidelines for Helicobacter pylori eradication recommend 7 days of a proton-pump inhibitor, clarithromycin (C), and either metronidazole (M) or amoxycillin (A). A shorter course would be cheaper and could be as effective.

AIM

This study was designed to investigate the efficacy of three 5-day regimens based on lansoprazole (L).

METHODS

168 dyspepsia patients with H. pylori infection were randomized to receive a 5-day course of either LCM, LAC or CALM, and a 13C-urea breath test was performed after 4 weeks to assess eradication.

RESULTS

160 patients completed the study. Intention-to-treat eradication rates were as follows: LCM 81%, LAC 59%, CALM 88%. LCM and CALM gave significantly better eradication rates than LAC. There was no significant difference in adverse events across the three groups. Logistical regression analysis showed that the specific regimen used and the age of the patient were the only factors influencing eradication outcome.

CONCLUSIONS

Five days of CALM yields acceptable eradication rates, and is cheaper than conventional 7-day proton pump inhibitor-triple therapy. It appears to offer good results in metronidazole-resistant strains of H. pylori. A randomized trial comparing 5-day CALM with conventional 7-day therapy is needed before this regimen can be recommended for routine use.

Ferromagnetic hyperthermia: functional and histopathologic effects on normal rabbit ocular tissue

Ferromagnetic (FM) hyperthermia has previously been evaluated in a rabbit tumour model of ocular melanoma. To study the effect of focal heating in normal rabbit eyes, FM seeds were implanted into a 14-mm episcleral plaque an heated to operating temperatures of 48 or 58 degrees C. Thermal induction was performed by placing rabbits in a uniform, oscillating (11 kHz) magnetic field operating at 1200 W and as H-field strength of 265 A/m. Eyes were heated for 60 min with continuous scleral temperature monitoring. Hyperthermic effects were monitored by direct opthalmic examination, fundus photography, serial electroretinography and histopathology. Intraocular temperatures were mapped with direct fiberoptic thermometry. All treatment effects were confined to the area covered by the episcleral plaque. Direct ophthalmoscopic examination revealed early retinal whitening during heat induction followed by localized exudative retinal detachments, limited to the area of the retinal surface overlying the plaque, that resolved spontaneously. Serial electroretinography was virtually indistinguishable between the 48 and 54 degrees C temperature groups. We noted a minimal alteration in a- and b-wave amplitudes with no changes in implicit times. Histopathology at 3 weeks post-treatment documented chorioretinal scarring overlying the thermal plaque treatment zone. No evidence of heamorrhage infection, cataract or scleral thinning was noted. This study documents the apparent focal containment of thermal effects with FM heating utilizing operating temperatures ad high as 54 degrees C for 60 min, and discloses no evidence of diffuse ocular toxicity.

Antioxidants, Helicobacter pylori and stomach cancer in Venezuela

A randomized chemoprevention trial on precancerous lesions of the stomach is being conducted in Tachira State, Venezuela. The aims of the study are to evaluate the efficacy of vitamin supplementation in preventing the progression rate of precancerous lesions. Here we report on the pilot phase of the study in which two antioxidant preparations were evaluated on their ability to raise antioxidant levels in plasma and in gastric juice. The study aimed also to determine the antibiotic sensitivity profiles of Helicobacter pylori isolates prevalent in the area. Forty-three subjects with precancerous lesions (chronic gastritis, chronic atrophic gastritis, intestinal metaplasia and dysplasia) of the stomach were randomized to one of two antioxidant treatments. Treatment 1 (250 mg of standard vitamin C, 200 mg of vitamin E and 6 mg of beta-carotene three times a day) or treatment 2 (150 mg of standard vitamin C, 500 mg of slow release vitamin C, 75 mg of vitamin E and 15 mg of beta-carotene once a day) for 7 days. Blood levels of total vitamin C, beta-carotene and alpha-tocopherol and gastric juice levels of ascorbic acid and total vitamin C were measured before and after treatment on day 8. Both treatments increased the plasma levels of total vitamin C, beta-carotene and alpha-tocopherol/cholesterol but not those of ascorbic acid or total vitamin C in gastric juice. Treatment 1 was the best choice and resulted in a greater increase in the plasma levels of beta-carotene and alpha-tocopherol. H. pylori was cultured from 90% of the gastric biopsies; 35 isolates were identified which were highly resistant to metronidazole, a front-line antibiotic recommended against H. pylori in other settings.

An automated dry-slide enzymatic method evaluated for measurement of creatinine in serum

We evaluated an automated dry-slide enzymatic method involving creatinine iminohydrolase for measurement of creatinine in serum with the Kodak Ektachem analyzer. The means (and SD) for three commercially available quality-control sera, analyzed during eight weeks, were 9.7 (1.0), 16.6 (0.9), and 61 (2.1) mg/L. The regression equation for 105 samples measured with the Technicon SMAC (x) and Ektachem Analyzers (y) was: y = (0.89 +/- 0.007)x + (1.7 +/- 0.3) mg/L and for 170 samples measured with the Beckman Astra (x) and Ektachem analyzers (y): y = (1.00 +/- 0.005)x - (1.9 +/- 0.16) mg/L. Sixty-one samples from renal-transplant patients showed nearly the same agreement. The enzymatic method had no interference from substances that interfere with many Jaffé methods for creatinine, including acetoacetate. The drugs cephalothin and cephoxitin did not interfere, but 5-fluorocytosine interfered significantly with creatinine in the Ektachem method. Values for several ketone-positive sera were 5 to 10 mg/L higher by the Astra relative to the Ektachem. Grossly hemolyzed or lipemic samples were analyzed without difficulty. We conclude that this enzymatic method for creatinine in serum has the speed and precision necessary for routine clinical laboratory use and, except for one drug, the method appears to be specific for creatinine.

An automated dry-slide enzymatic method evaluated for measurement of creatinine in serum

We evaluated an automated dry-slide enzymatic method involving creatinine iminohydrolase for measurement of creatinine in serum with the Kodak Ektachem analyzer. The means (and SD) for three commercially available quality-control sera, analyzed during eight weeks, were 9.7 (1.0), 16.6 (0.9), and 61 (2.1) mg/L. The regression equation for 105 samples measured with the Technicon SMAC (x) and Ektachem Analyzers (y) was: y = (0.89 +/- 0.007)x + (1.7 +/- 0.3) mg/L and for 170 samples measured with the Beckman Astra (x) and Ektachem analyzers (y): y = (1.00 +/- 0.005)x - (1.9 +/- 0.16) mg/L. Sixty-one samples from renal-transplant patients showed nearly the same agreement. The enzymatic method had no interference from substances that interfere with many Jaffé methods for creatinine, including acetoacetate. The drugs cephalothin and cephoxitin did not interfere, but 5-fluorocytosine interfered significantly with creatinine in the Ektachem method. Values for several ketone-positive sera were 5 to 10 mg/L higher by the Astra relative to the Ektachem. Grossly hemolyzed or lipemic samples were analyzed without difficulty. We conclude that this enzymatic method for creatinine in serum has the speed and precision necessary for routine clinical laboratory use and, except for one drug, the method appears to be specific for creatinine.

Enzymic determination of citrate in serum and urine, with use of the Worthington "ultrafree" device

We describe an enzymic method for conveniently measuring citrate in serum or urine. Interfering enzyme proteins are removed by a disposable ultrafilter ("Ultrafree"; Worthington Diagnostics), obviating the need for hazardous protein precipitants. A 50 mmol/L Tris buffer adequately controls pH, no lactate dehydrogenase is necessary in the reagents, and the reaction of citrate catalyzed by citrate lyase (EC 4.1.3.6) is complete in 2-3 min. Within-run and day-to-day coefficients of variation were 7.5% and 5.4%, respectively. Serum citrate concentrations for 20 apparently healthy persons ranged from 0.08 to 0.17 mmol/L (mean 0.12, SD 0.03). Urinary citrate excretion by six normal volunteers ranged from 2.2 to 4.4 mmol/24 h. We observed no detectable changes in citrate in whole blood stored at room temperature for 90 min or longer. Overall, the method is faster and less hazardous than other methods for citrate that require protein precipitation.

Enzymic determination of citrate in serum and urine, with use of the Worthington "ultrafree" device

We describe an enzymic method for conveniently measuring citrate in serum or urine. Interfering enzyme proteins are removed by a disposable ultrafilter ("Ultrafree"; Worthington Diagnostics), obviating the need for hazardous protein precipitants. A 50 mmol/L Tris buffer adequately controls pH, no lactate dehydrogenase is necessary in the reagents, and the reaction of citrate catalyzed by citrate lyase (EC 4.1.3.6) is complete in 2-3 min. Within-run and day-to-day coefficients of variation were 7.5% and 5.4%, respectively. Serum citrate concentrations for 20 apparently healthy persons ranged from 0.08 to 0.17 mmol/L (mean 0.12, SD 0.03). Urinary citrate excretion by six normal volunteers ranged from 2.2 to 4.4 mmol/24 h. We observed no detectable changes in citrate in whole blood stored at room temperature for 90 min or longer. Overall, the method is faster and less hazardous than other methods for citrate that require protein precipitation.

Effect of molecular charge on choroid-plexus permeability: Tracer studies with cationized ferritins

The permeability of the choroid plexus and renal glomerulus to intravenously injected native, anionic ferritin and various cationic ferritin derivatives was studied in normal rats by electron microscopy. In both structures, anionic, native ferritin was largely confined to the circulatory compartment while the cationic forms penetrated and accumulated within the filtration barriers. In the choroid plexus, cationic ferritin concentrated in relationship to the endothelial fenestrations and the subendothelial basal lamina region. In the glomerulus, there was also an inner concentration of cationic tracer and, in addition, an aggregation of tracer along the outer, subepithelial portion of the basal lamina. The results indicate that the localization of tracer within the filtration barrier of both the choroid plexus and renal glomerulus is directly related to the tracer's isoelectric point. The findings suggest that the choroid plexus, like the glomerulus, contains fixed anionic groups within the capillary wall which influence its permeability.

The Worthington "ultrafree" device evaluated for determination of ultrafiltrable calcium in serum

We evaluated a commercially-available disposable device ("Ultrafree," Worthington Diagnostics) for the anaerobic preparation of protein-free ultrafiltrates from serum for measurement of ultrafiltrable calcium. Sufficient filtrate for the analysis is obtained with 10 min from 0.2 to 0.4 mL of serum at room temperature. We assessed these ultrafilters with regard to permeability of calcium citrate, exclusion of proteins, frequency of leakage, and effect of temperature on results. Within-run and day-to-day coefficients of variation for human serum pools were 1.2 and 1.5%, respectively. Reference intervals (in mmol/L) for total (2.16-2.58), ultrafiltrable (1.44-1.67), dialyzable (1.25-1.41), and ionized (1.04-1.25) calcium have been determined for a healthy population of 69 women and 81 men, ages to 18 to 65 years. The device appears to be the most practicable yet available for use in making this measurement.

The Worthington "ultrafree" device evaluated for determination of ultrafiltrable calcium in serum

We evaluated a commercially-available disposable device ("Ultrafree," Worthington Diagnostics) for the anaerobic preparation of protein-free ultrafiltrates from serum for measurement of ultrafiltrable calcium. Sufficient filtrate for the analysis is obtained with 10 min from 0.2 to 0.4 mL of serum at room temperature. We assessed these ultrafilters with regard to permeability of calcium citrate, exclusion of proteins, frequency of leakage, and effect of temperature on results. Within-run and day-to-day coefficients of variation for human serum pools were 1.2 and 1.5%, respectively. Reference intervals (in mmol/L) for total (2.16-2.58), ultrafiltrable (1.44-1.67), dialyzable (1.25-1.41), and ionized (1.04-1.25) calcium have been determined for a healthy population of 69 women and 81 men, ages to 18 to 65 years. The device appears to be the most practicable yet available for use in making this measurement.