The validity of adenosine triphosphate measurement in detecting endoscope contamination.

BACKGROUND: Endoscopic procedures are vital to gastrointestinal disease diagnosis and management, but risk infection transmission. In Australia, endoscopes undergo monthly-to-quarterly microbiological testing, to prevent patient infection. Endoscopes are used more frequently, meaning contamination may not be detected by this surveillance before infection transmission occurs. AIM: To evaluate the use of adenosine triphosphate (ATP) measurement, alongside standard microbiological cultures, in detecting endoscope contamination before high-level disinfection. Using these results, we also aimed to confirm the efficacy of manual cleaning in reducing levels of ATP and cfu/mL. METHODS: Seventeen in-clinical-use gastroscopes and 24 in-clinical-use colonoscopes from the Liverpool Hospital Endoscopy unit were sampled across three separate cleaning stages before high-level disinfection. Colony counts and ATP measurements were then performed on these samples. FINDINGS: The correlation between the cfu/mL and RLU of samples collected from colonoscopes was 0.497 (95% confidence interval: 0.28-0.66; P < 0.0001). The correlation between cfu/mL and RLU for samples collected from gastroscopes was 0.377 (0.08-0.61; P = 0.0138). RLU and cfu/mL values were shown to fall significantly (P < 0.005) following precleaning and manual cleaning. CONCLUSION: There was a significant correlation between ATP and cfu/mL measured from samples collected before high-level disinfection. Precleaning and manual cleaning were shown to reduce ATP and microbiological load significantly. ATP measurement can be performed within minutes with little training and produces results that are easy to interpret. These findings warrant further research on the utility of ATP measurement as a screening tool for detecting endoscope contamination after high-level disinfection.

Advances in gastrointestinal endoscopy.

Endoscopy has a rapidly expanding role in diagnosis and management of gastrointestinal disease.

Endoscopic band ligation for non-variceal non-ulcer gastrointestinal hemorrhage.

BACKGROUND: There is no consensus as to the best treatment for non-variceal, non-ulcer gastrointestinal hemorrhage. Endoscopic band ligation is an inexpensive, readily available, and easily learned technique in contrast to conventional thermal methods of endoscopic hemostasis. We present the preliminary results of an open trial using endoscopic band ligation for non-variceal, non-ulcer bleeding in the gastrointestinal tract. METHODS: Eighteen patients were treated by band ligation between June 1996 and November 1997. The lesions treated were: arteriovenous malformations in 10, Dieulafoy's lesions in 4, Mallory-Weiss tear in 2, and post-colonic polypectomy bleeding in 2. RESULTS: Endoscopic band ligation was successful in 17 of 18 cases, with a follow-up period ranging from 2 to 18 months. The remaining case, a duodenal Dieulafoy's lesion, bled again at 24 hours but was successfully treated by adrenalin injection. CONCLUSIONS: Endoscopic band ligation is effective for non-variceal, non-ulcer bleeding. It has the advantage of ease of use and is relatively inexpensive.

Immunological privilege in the eye: a review.

The eye enjoys a privileged immunological status, in contrast to most sites in the body. Historically, it was thought that the eye, due to its lack of lymphatics, was not subject to the same immune surveillance as other tissues. In opposition to this, recent study has revealed that presenting foreign material via the eye produces marked effects on systemic immunity, leading to a state of tolerance when the same foreign antigen is presented systemically. The immunology of the eye is now known to consist of a myriad of local and systemic effects.

Differential enhancement of HLA-B27 by interferon.

To further examine the role of the HLA-B27 antigen in the pathogenesis of disorders such as anterior uveitis and ankylosing spondylitis, we have measured the level of enhancement of this antigen on peripheral blood lymphocytes and compared it with that of the class I HLA antigens HLA-A2 and HLA-B7 following interferon treatment. We found that the level of enhancement of HLA-B7 was greater than that of HLA-A2 or -B7 following treatment by alpha or gamma interferon (p less than 0.002). Similarly, the level of enhancement of HLA-B7 was greater than that of HLA-A2 (p less than 0.002) (Mann Whitney U-test). A differential enhancement of HLA-B27 by lymphokines may be important in the pathogenesis of HLA-B27-related disorders.

HLA antigens in the iris and aqueous humor gamma interferon levels in anterior uveitis.

The induced expression of HLA antigens on a variety of tissues involved in autoimmune diseases has been reported by several groups. In this study, we have examined the expression of HLA antigens in iris biopsy specimens from patients with anterior uveitis and compared them to patients with noninflammatory senile cataracts. In addition, we measured the levels of gamma interferon in the aqueous humor of the same subjects. Our results show that there was induced expression of class I and class II HLA antigens in iris biopsies from patients with anterior uveitis and that the level of induced expression correlated with the concentration of gamma interferon found in the aqueous humor. These results suggest that induced expression of HLA antigens on iris cells may play a role in the pathogenesis of anterior uveitis and that gamma interferon may be one of the mediators for this induced expression.

HLA antigens in ocular tissues. III. Antigen presentation by gamma interferon-treated cultured uveal cells.

In previous studies we have shown that normal human uveal cells, with the exception of vascular endothelium, do not express class I or class II HLA antigens in vivo. Class I antigens are induced in vitro by a variety of cytokines, while class II antigens are only induced by gamma interferon. In this study we examine the capacity of cultured uveal cells, rendered class II HLA antigen positive by gamma interferon, to present antigen to T cells. Cultured uveal cells were found to present antigen (tetanus toxoid, PPD, and Candida albicans) to T cells, but only when they were pretreated with gamma interferon. This function of uveal cells was antigen specific and MHC restricted and was blocked by class II-specific monoclonal antibodies, indicating the crucial role of class II HLA antigens in antigen presentation.

Increased serum neopterin levels in patients with acute anterior uveitis.

We examined the sera of 50 patients with anterior uveitis (AU) for the presence of interferon and neopterin, an interferon induced pteridine derivative. Neopterin release is induced by gamma interferon and it is a more stable compound. Our results indicate that although there is no detectable differences in serum interferon levels between patients and controls, neopterin levels were elevated in patients with active disease, possibly indicating a localised activation of the interferon system.

Association of complement allotype C4B2 with anterior uveitis.

We have studied allotypes of the fourth component of complement (C4) in 44 patients with inflammatory eye disease in order to define genetic susceptibility factors further. Twenty-six patients had uveitis (18 had anterior uveitis) and 18 patients had retinal vasculitis. There was an increased incidence of the C4B2 allotype in patients with anterior uveitis (pc less than 0.002), especially in HLA B27 positive males. In contrast, there was no increased incidence of specific allotypes in patients with posterior uveitis or retinal vasculitis. This genetic association may form part of a disease susceptibility supratype in patients with anterior uveitis.

HLA antigens in ocular tissues. I. In vivo expression in human eyes.

The eye is a common site for autoimmune inflammatory diseases, many of which are linked to HLA antigens. The role of these HLA phenotypes in the disease process is presently unknown. In view of the importance of HLA antigens to immune responses, a knowledge of the distribution of HLA antigens in ocular tissues may aid in our understanding of the role of these antigens in disease production or susceptibility. Apart from the cornea, the expression of HLA antigens in human ocular tissues has not been thoroughly investigated. In this study we examined the in vivo expression of HLA antigens in postmortem human eyes using immunohistochemical techniques. The majority of ocular cells were found not to express class I or class II HLA antigens, with the exception of the blood vessel endothelium, which was uniformly class I-positive. The significance of these results is discussed in relation to ocular immunity.

Expression of HLA antigens on the human uvea.

We examined the expression of HLA antigens on post-mortem human uveal tissues and on cultured uveal cells. There was no in vivo expression of class I or class II antigens in these tissues, except for the blood vessel endothelium which expressed class I but not class II antigens. Tissue cultured uveal cells were found to express class I antigens. The effect of interferon-alpha and interferon-gamma on the in vitro expression of these antigens was examined. Class I HLA antigen expression was enhanced by both interferon-alpha and interferon-gamma, while class II HLA antigens were induced on up to 100% of cultured cells, but only by interferon-gamma. These findings are discussed in their relation to immune mechanisms occurring in ocular inflammatory disorders.