Determination of Optimum Sanitizer Levels for Prevention of Salmonella Cross-Contamination of Mature Round Tomatoes in a Laboratory Model Flume System

Salmonella has been reported to be involved in several foodborne illness outbreaks, many of which resulted from consumption of raw tomatoes. This research aimed to optimize and evaluate the concentration of free chlorine (hypochlorous acid [HOCl]) used as a sanitizer to prevent cross-contamination of tomatoes inoculated with a cocktail of five rifampin-resistant Salmonella enterica serovars in a laboratory-based model flume system. Organic load, prepared using sterilized Scotts Premium Topsoil, was added in different quantities to the flume wash water to simulate real-world packinghouse conditions. In a typical packinghouse operation utilizing a recirculating flume system, the organic matter washed from tomato surfaces accumulates over time. In this study, different concentrations (0, 25, 50, 75, and 100 ppm) of HOCl were used as sanitizers under three organic load conditions (0, 650, and 1,000 mg/L chemical oxygen demand). Results showed that 100 ppm of HOCl was necessary to prevent Salmonella cross-contamination of uninoculated tomatoes in the model flume system in the presence of organic loading. Also, when treated with 100 ppm of HOCl, Salmonella levels were reduced by >4.5 log CFU per tomato from inoculated tomatoes in the presence of organic load. At 75 ppm of HOCl, Salmonella cross-contamination was prevented, but only in the absence of organic loading. In studies in which plate counts were negative, whole tomato enrichment studies were performed. No cross-contamination of uninoculated tomatoes was recorded when 100 ppm of HOCl was used, even in the presence of high organic load (1,000 mg/L chemical oxygen demand). Although sanitizer application reduces contamination on tomato surfaces, the primary function of sanitizers in the wash water is to prevent cross-contamination.

Control of Salmonella Cross-Contamination between Green Round Tomatoes in a Model Flume System

Tomato Best Management Practices require Florida packers to treat tomatoes in a flume system containing at least 150 ppm of free chlorine or other approved sanitizer. However, research is needed to determine the ability of these sanitizers to prevent the transfer of pathogens from contaminated to uncontaminated tomatoes, particularly under realistic packinghouse conditions. The goal of this research was to assess the minimum levels of sanitizer needed to prevent Salmonella cross-contamination between tomatoes in a model flume system under clean conditions and conditions where organic matter was added. Inoculated tomatoes (ca. 8.3 log CFU per tomato) were treated along with uninoculated tomatoes in a model flume system containing 0, 10, or 25 ppm of hypochlorous acid (HOCl) under organic loading conditions of 0, 500, or 4,000 ppm of chemical oxygen demand (COD). In the absence of HOCl, uninoculated tomatoes were highly contaminated (ca. 5 log CFU per tomato) by 15 s. No contamination was detectable (<2 log CFU per tomato) on uninoculated tomatoes when HOCl was present, except with 10 ppm at 4,000 ppm of COD, suggesting failure of 10 ppm of HOCl as a sanitizer under very high organic loading conditions. In the presence of HOCl or peroxyacetic acid, Salmonella was undetectable (<1 log CFU/ml) in the model flume water samples after 2 and 30 s, respectively. Upon enrichment, none of the uninoculated tomatoes treated with 25 ppm of HOCl for 120 s were positive for Salmonella, even in the presence of organic loading at 500 ppm of COD. Based on these findings, 25 ppm of HOCl may be adequate to prevent cross-contamination when the concentration is properly maintained, COD does not exceed 500 ppm, and tomatoes are treated for at least 120 s. Further validation in a larger commercial setting and using higher organic loading levels is necessary because managing HOCl at this low concentration is difficult, especially in a recirculating system. The use of less sanitizer by packers could reduce chemical and disposal costs.

Effect of overhead spray and brush roller treatment on the survival of Pectobacterium and Salmonella on tomato surfaces

Overhead spray and brush roller (OSBR) treatment has been shown to remove significantly more Salmonella from tomato surfaces than flume treatment. However, OSBR is not widely used in tomato packing facilities compared with other commodities, and little is known about whether brushing causes microabrasions or other physical damage. Bacteria such as Pectobacterium, a soft rot-producing plant pathogen, and Salmonella, a human pathogen, show increased survival and growth on damaged tomato surfaces. This study evaluated whether OSBR treatment had a negative effect on the safety and/or marketability of tomatoes by examining its effect on Pectobacterium and Salmonella survival. Pectobacterium survival was evaluated on inoculated tomatoes that were OSBR treated with water or sanitizer (100 ppm of NaOCl, 5 ppm of ClO2, or 80 ppm of peracetic acid). A 15-s OSBR treatment using water or sanitizer achieved a 3-log CFU/ml reduction in Pectobacterium levels. Survival of Pectobacterium and Salmonella on OSBR-treated, untreated, and puncture-wounded tomatoes stored at 25°C and 75 to 85 % relative humidity for 7 days was also assessed. Both Pectobacterium and Salmonella populations declined rapidly on OSBR-treated and untreated tomatoes, indicating that brushing does not damage tomato fruit to the extent of promoting better pathogen survival. In contrast, the survival of both organisms was significantly (P ≤ 0.05) higher on artificially wounded fruit. These results indicate that OSBR treatment does not increase the survival and growth of Pectobacterium or Salmonella on tomato surfaces and that it is effective in reducing Pectobacterium levels on the surface of inoculated tomatoes. These results suggest that, if used properly, an OSBR system in packinghouses is effective in removing surface contamination and does not affect tomato quality or safety.

Salmonella transfer potential onto tomatoes during laboratory-simulated in-field debris removal

Florida Tomato Good Agricultural Practices (T-GAPs) mandate the removal of dirt and debris from tomatoes during harvest but do not provide any specific regulations or guidance; thus, the current practice of using cloths needs to be evaluated. This study examined Salmonella transfer from inoculated green tomatoes to uninoculated cloths and from inoculated cloths to uninoculated tomatoes, upon single and multiple touches. Tomatoes were spot inoculated with a rifampin-resistant Salmonella cocktail (10(7) CFU per tomato) and were touched with cloth (clean, dirty-dry, dirty-wet) at 0, 1, or 24 h postinoculation. Salmonella was enumerated on tryptic soy agar, followed by enrichments when necessary. The transfer direction was then reversed by touching freshly inoculated cloths with uninoculated tomatoes. Transfer coefficients (TCs) were then calculated. Salmonella TCs from inoculated tomato and cloth were highest when the inoculum was wet (0.44 ± 0.13 to 0.32 ± 0.12), regardless of the condition of the cloth. Although Salmonella TCs from inoculated tomato to uninoculated cloth decreased significantly when the inoculum was dried (0.17 ± 0.23 to 0.01 ± 0.00), low levels of Salmonella were detected on cloth even after 24 h of drying. Inoculated dirty cloth did not transfer more Salmonella compared with inoculated clean cloth, and Salmonella survival was not higher on dirty cloth. When inoculated clean cloth (wet) was touched with 25 tomatoes, significantly higher levels of Salmonella were transferred to the first, second, and fourth tomatoes (0.03 ± 0.10 to 0.09 ± 0.02). However, inoculated dirty-wet (below limit of detection) and dirty-dry (0.00 to 0.04 ± 0.01) cloths transferred similar levels of Salmonella to all 25 tomatoes. Results indicate a low risk of potential Salmonella contamination when the same cloth is used multiple times for debris removal, especially under high moisture levels. Results also show that the use of dirty cloths did not increase the risk of Salmonella cross-contamination.

The cost of treatment failure: resource use and costs incurred by hepatitis C virus genotype 1-infected patients who do or do not achieve sustained virological response to therapy

Chronic hepatitis C virus (HCV) infection places a considerable economic burden on health services. Cost-effectiveness analyses of antiviral treatment for patients with chronic HCV infection are dependent on assumptions about cost reductions following sustained virological response (SVR) to therapy. This study quantified the medium-term difference in health resource usage and costs depending on treatment outcome. Retrospective chart review of patients with HCV genotype 1 infection who had received at least 2 months pegylated interferon and ribavirin therapy, with known treatment outcome was conducted. Disease status was categorized as chronic hepatitis, cirrhosis or decompensated liver disease. Health resource use was documented for each patient in each disease state. Unit costs were from the NHS 'Payment by Results' database and the British National Formulary. One hundred and ninety three patients (108 SVR, 85 non-SVR) with mean follow-up of 3.5 (SVR) and 4.9 (non-SVR) years were enrolled. No SVR patient progressed to a more severe liver disease state. Annual transition rates for non-SVR patients were 7.4% (chronic hepatitis to cirrhosis) and 4.9% (cirrhosis to decompensated liver disease). By extrapolation of modelled data over a 5-year post-treatment period, failure of patients with chronic hepatitis to achieve SVR was associated with a 13-fold increase (roughly £2300) in costs, whilst for patients who were retreated, the increase was 56-fold, equating to more than £10 000. Achievement of an SVR has significant effects on health service usage and costs. This work provides real-life data for future cost-effectiveness analyses related to the treatment for chronic HCV infection.

Global gene expression changes in Candidatus Liberibacter asiaticus during the transmission in distinct hosts between plant and insect

Huanglongbing (HLB) or citrus greening disease is a destructive disease of citrus worldwide, which is associated with Candidatus Liberibacter asiaticus. This phloem-limited fastidious pathogen is transmitted by the Asian citrus psyllid, Diaphorina citri, and appears to be an intracellular pathogen that maintains an intimate association with the psyllid or the plant throughout its life cycle. The molecular basis of the interaction of this pathogen with its hosts is not well understood. We hypothesized that, during infection, Ca. L. asiaticus differentially expresses the genes critical for its survival and/or pathogenicity in either host. To test this hypothesis, quantitative reverse transcription-polymerase chain reaction was performed to compare the gene expression of Ca. L. asiaticus in planta and in psyllid. Overall, 381 genes were analysed for their gene expression in planta and in psyllid. Among them, 182 genes were up-regulated in planta compared with in psyllid (P < 0.05), 16 genes were up-regulated in psyllid (P < 0.05) and 183 genes showed no statistically significant difference (P ≥ 0.05) in expression between in planta and in psyllid. Our study indicates that the expression of the Ca. L. asiaticus genes involved in transcriptional regulation, transport system, secretion system, flagella assembly, metabolic pathway and stress resistance are changed significantly in a host-specific manner to adapt to the distinct environments of plant and insect. To our knowledge, this is the first large-scale study to evaluate the differential expression of Ca. L. asiaticus genes in a plant host and its insect vector.

Transcriptional studies of the hrpM/opgH gene in Pseudomonas syringae during biofilm formation and in response to different environmental challenges

Pseudomonas syringae pv. syringae strain FF5 is a phytopathogen that causes a rapid dieback on ornamental pear trees. In the present study, the transcriptional expression of hrpM/opgH, algD, hrpR and rpoD was evaluated in P. syringae FF5 and FF5.M2 (hrpM/opgH mutant). The temporal expression of these genes was evaluated during biofilm formation, the hypersensitive reaction (HR) on tobacco plants, and when the bacteria were subjected to different environmental stresses. The results indicate that mutations in hrpM negatively impair several traits including biofilm formation, the ability to cause disease in host plants and the HR in non-host plants, and the expression of hrpR, a regulatory gene modulating the latter two traits. Furthermore, FF5.M2 was decreased in swarming motility and unable to respond to different environmental challenges. Interestingly, FF5.M2 showed an exponential increase in the expression of algD, which is the first gene to be transcribed during the biosynthesis of the alginate, a virulence factor in P. syringae. The expression of both hrpM and algD were required for biofilm formation, and hrpM was expressed earlier than algD during biofilm development. These findings indicate that hrpM expression is required for several traits in P. syringae and plays an important role in how this bacterium responds to environmental challenges.

Simple and rapid capillary zone electrophoresis method for the detection of coronamic acid, a precursor to the Pseudomonas syringae phytotoxin coronatine

The phytotoxin coronatine (COR) is produced by various pathovars of the plant pathogen Pseudomonas syringae, which infects a wide variety of crops. COR consists of two distinct moieties, coronafacic acid (CFA) and coronamic acid (CMA), which are derived from a modified polyketide pathway and isoleucine, respectively. Mutants defective in the CMA or CFA structural gene clusters have been used to study COR biosynthesis, and these mutants are commonly characterized using high-performance liquid chromatography (HPLC). Although the same extraction and HPLC method can be used for detection and quantification of COR and CFA, the detection of CMA by HPLC requires different fractionation and HPLC separation procedures, which are tedious and labor intensive. In this study, we used capillary zone electrophoresis (CZE) as a fast and accurate detection method for the quantification of CMA present in the culture supernatant of P. syringae pv. glycinea (Psg) PG4180 and P. syringae pv. tomato (Pst) DC3000. Analysis was performed by CZE using 100 mM phosphate buffer (pH 2.5) as a separating buffer, an applied voltage of 12 kV, and UV detection at 214 nm. Selected mutants defective in COR biosynthesis were used to validate CZE as a detection method. CMA production by Psg strain 18a/90, which lacks the COR gene cluster, and derivatives of 18a/90 was also evaluated. Furthermore, a procedure for the extraction and detection of CMA present inside the cells of Psg 18a/90 was developed. In conclusion, CZE was shown to be a rapid and sensitive method for the detection and quantification of CMA in P. syringae.

Microbial Diagnostic Array Workstation (MDAW): a web server for diagnostic array data storage, sharing and analysis

Background

Microarrays are becoming a very popular tool for microbial detection and diagnostics. Although these diagnostic arrays are much simpler when compared to the traditional transcriptome arrays, due to the high throughput nature of the arrays, the data analysis requirements still form a bottle neck for the widespread use of these diagnostic arrays. Hence we developed a new online data sharing and analysis environment customised for diagnostic arrays.

Methods

Microbial Diagnostic Array Workstation (MDAW) is a database driven application designed in MS Access and front end designed in ASP.NET.

Conclusion

MDAW is a new resource that is customised for the data analysis requirements for microbial diagnostic arrays.

Proton pump inhibitor treatment initiated prior to endoscopic diagnosis in upper gastrointestinal bleeding

BACKGROUND

There is conflicting evidence regarding the clinical efficacy of proton pump inhibitors (PPI) initiated prior to endoscopy in patients with upper gastrointestinal bleeding.

OBJECTIVES

We aimed to systematically review evidence from randomised controlled trials (RCTs) that studied PPI treatment initiated before endoscopy in patients with upper gastrointestinal bleeding.

SEARCH STRATEGY

A search was undertaken according to the Cochrane Upper Gastrointestinal and Pancreatic Diseases model using CENTRAL, (The Cochrane Library), MEDLINE, EMBASE and CINAHL databases and major conference proceedings up to September 2005. The literature search was re-run in February 2006.

SELECTION CRITERIA

Types of studies: Randomised controlled trials (RCTs).

TYPES OF PARTICIPANTS

Hospitalised patients with unselected upper gastrointestinal bleeding. Types of interventions: Active treatment with a PPI (oral or intravenous) and control treatment with either placebo or an histamine-(2) receptor antagonist (H(2)RA). Types of outcome measures: Assessed at 30 days: mortality, rebleeding and surgery. Also assessed were stigmata of recent haemorrhage at index endoscopy, length of hospital stay and blood transfusion requirements.

DATA COLLECTION AND ANALYSIS

At least two reviewers assessed the eligibility criteria of each study and extracted data regarding outcomes and factors affecting methodological quality.

MAIN RESULTS

Five RCTs were included for review. No further RCTS were identified in an updated literature search. Four trials comprising a total of 1512 patients in total reported data for all randomised patients. There was no statistical heterogeneity among trials for the outcomes of mortality, rebleeding and surgery. There were no statistically significant differences in rates of mortality, rebleeding or surgery between PPI and control treatment. Pooled mortality rates were 6.1% and 5.5% respectively (odds ratio (OR)1.12; 95% CI 0.72 to 1.73). Pooled rebleeding rates were 13.9% and 16.6% respectively (OR 0.81; 95%CI 0.61 to 1.09). Pooled rates for surgery were 9.9% and 10.2% respectively (OR 0.96 95% CI 0.68 to 1.35). PPI treatment compared to control significantly reduced the proportion of patients with stigmata of recent haemorrhage at index endoscopy; pooled rates were 37.2% and 46.5% respectively (OR 0.67; 95% CI 0.54 to 0.84). For the continuous outcomes, namely length of hospital stay and blood transfusion requirements, quantitative analysis could not be performed.

AUTHORS' CONCLUSIONS

PPI treatment initiated prior to endoscopy in patients with upper gastrointestinal bleeding significantly reduces the proportion of patients with stigmata of recent haemorrhage at index endoscopy. However, there is no evidence that PPI treatment affects clinically important outcomes, namely mortality, rebleeding or need for surgery.

CorR regulates multiple components of virulence in Pseudomonas syringae pv. tomato DC3000

The phytotoxin coronatine (COR) is produced by various pathovars of Pseudomonas syringae, including P. syringae pv. tomato DC3000, which is pathogenic on crucifers and tomato, and P. syringae pv. glycinea PG4180, a soybean pathogen. The COR molecule contains two distinct components, coronafacic acid (CFA) and coronamic acid (CMA), which are intermediates in the COR biosynthetic pathway. In P. syringae pv. tomato DC3000, it is not clear whether corR, which encodes a response regulator, positively regulates CFA and CMA synthesis as it does in P. syringae pv. glycinea PG4180. In this study, a corR mutant of P. syringae pv. tomato DC3000 was constructed and was shown to be defective in the production of COR, CFA, and CMA. Furthermore, disease severity was greatly reduced in tomato plants inoculated with the corR mutant compared with wild-type P. syringae pv. tomato DC3000. We also showed that a mutation in hrpL, which encodes an alternate RNA polymerase sigma factor (sigmaL) required for the expression of genes encoding components of the type III secretion system, abrogated production of COR in P. syringae pv. tomato DC3000. The presence of a potential hrp box, the recognition site for sigmaL, upstream of corR suggested that corR might be regulated by hrpL. This was confirmed in reverse-transcription polymerase chain reaction experiments showing that the upstream effector gene holPtoAA, which was associated with the hrp box, was cotranscribed with corR. Furthermore, studies also were conducted to investigate whether mutations in corR had effects on the expression of hrpL. The corR mutant of P. syringae pv. tomato DC3000 showed both a reduction and delay in the expression of hrpL and was impaired in its ability to elicit a hypersensitive response on Nicotiana benthamiana. A putative CorR-binding site was identified upstream of hrpL, and gel shift studies confirmed the binding of CorR to this region. These results indicate that corR directly impacts the expression of the hrp regulon in P. syringae.

Macrophage activation syndrome and other systemic inflammatory conditions after BMT

Autologous hematopoietic cell transplantation (HCT) is being used to treat autoimmune diseases refractory to conventional therapy, including rheumatoid arthritis. Macrophage activation syndrome (MAS) is a descriptive term for a systemic inflammatory disorder that has been described in patients with juvenile rheumatoid arthritis (JRA). This case report describes a young adult with systemic JRA (sJRA) who developed MAS on day # 12 post-autologous transplantation. The patient developed high fever, laboratory evidence of disseminated intravascular coagulation (DIC), hepatocellular injury, pancytopenia and hyper-ferritinemia. All viral, bacterial and fungal studies were negative and the patient improved with high-dose glucocorticosteroid and cyclosporine therapy. Extreme elevation of serum ferritin was documented and helpful in monitoring response to therapy. A number of systemic inflammatory syndromes have been described in association with HCT. These include DIC, 'engraftment syndrome,' infection-associated hemophagocytic syndrome and familial hemophagocytic lymphohistiocytosis. Macrophage activation syndrome presents with features of DIC and is closely related or identical to infection-associated hemophagocytic syndrome. The diagnosis needs to be established in a timely fashion because early and appropriate treatment may improve outcome.

Novel virulence gene of Pseudomonas syringae pv. tomato strain DC3000

Previously, we conducted a mutant screen of Pseudomonas syringae pv. tomato strain DC3000 to identify genes that contribute to virulence on Arabidopsis thaliana plants. Here we describe the characterization of one mutant strain, DB4H2, which contains a single Tn5 insertion in PSPTO3576, an open reading frame that is predicted to encode a protein belonging to the TetR family of transcriptional regulators. We demonstrate that PSPTO3576 is necessary for virulence in DC3000 and designate the encoded protein TvrR (TetR-like virulence regulator). TvrR, like many other TetR-like transcriptional regulators, negatively regulates its own expression. Despite the presence of a putative HrpL binding site in the tvrR promoter region, tvrR is not regulated by HrpL, an alternative sigma factor that regulates the expression of many known DC3000 virulence genes. tvrR mutant strains grow comparably to wild-type DC3000 in culture and possess an intact type III secretion system. However, tvrR mutants do not cause disease symptoms on inoculated A. thaliana and tomato plants, and their growth within plant tissue is significantly impaired. We demonstrate that tvrR mutant strains are able to synthesize coronatine (COR), a phytotoxin required for virulence of DC3000 on A. thaliana. Given that tvrR mutant strains are not defective for type III secretion or COR production, tvrR appears to be a novel virulence factor required for a previously unexplored process that is necessary for pathogenesis.

Identification and characterization of a well-defined series of coronatine biosynthetic mutants of Pseudomonas syringae pv. tomato DC3000

To identify Pseudomonas syringae pv. tomato genes involved in pathogenesis, we carried out a screen for Tn5 mutants of P. syringae pv. tomato DC3000 with reduced virulence on Arabidopsis thaliana. Several mutants defining both known and novel virulence loci were identified. Six mutants contained insertions in biosynthetic genes for the phytotoxin coronatine (COR). The P. syringae pv. tomato DC3000 COR genes are chromosomally encoded and are arranged in two separate clusters, which encode enzymes responsible for the synthesis of coronafacic acid (CFA) or coronamic acid (CMA), the two defined intermediates in COR biosynthesis. High-performance liquid chromatography fractionation and exogenous feeding studies confirmed that Tn5 insertions in the cfa and cma genes disrupt CFA and CMA biosynthesis, respectively. All six COR biosynthetic mutants were significantly impaired in their ability to multiply to high levels and to elicit disease symptoms on A. thaliana plants. To assess the relative contributions of CFA, CMA, and COR in virulence, we constructed and characterized cfa6 cmaA double mutant strains. These exhibited virulence phenotypes on A. thalliana identical to those observed for the cmaA or cfa6 single mutants, suggesting that reduced virulence of these mutants on A. thaliana is caused by the absence of the intact COR toxin. This is the first study to use biochemically and genetically defined COR mutants to address the role of COR in pathogenesis.

Does detection of K-ras mutations in pancreatic juice influence clinical decision making?

The majority of patients with pancreatic cancer harbour mutations in the K-ras gene. This oncogene may be detected in material obtained at endoscopic retrograde cholangiopancreatography (ERCP), such as bile and pancreatic juice. Since a formal tissue diagnosis may be difficult to establish in pancreatic cancer, detection of K-ras in these materials is an attractive approach to diagnosis. A variety of molecular techniques has been used to detect K-ras, and frequency of the mutation may vary between different populations. In this issue of the European Journal of Gastroenterology and Hepatology, Boadas et al. collected pancreatic juice following secretin stimulation at the time of ERCP, and detected K-ras in 44% of patients with pancreatic cancer. They found the mutation in 16% of patients with chronic pancreatitis. Presence of the mutation, therefore, is not specific enough to recommend its use in the clinical diagnosis of pancreatic cancer. Chronic pancreatitis patients with the mutation may be at higher risk of developing pancreatic cancer than those patients without the mutation, but there is no clear consensus on management and follow-up of these patients.

Portal hemodynamics in fulminant hepatic failure as assessed by duplex Doppler ultrasonography

Portal hypertension usually occurs in patients with fulminant hepatic failure (FHF). There is, however, no information on portal venous hemodynamics in patients with FHF. Therefore, we studied the portal venous hemodynamics in patients with FHF using duplex Doppler ultrasonography. We measured the portal vein diameter, flow velocity, and volume flow with duplex Doppler ultrasonography in 29 patients with FHF and 15 patients with uncomplicated acute viral hepatitis. No significant difference was observed in the portal vein parameters in the two groups. Nineteen patients with FHF survived. No difference in portal flow velocity and flow rate was observed between survivors and nonsurvivors. A significantly lower portal flow velocity was observed in nine patients of FHF with ascites compared with those without ascites (12.29+/-2.81 vs 16.26+/-4.87 cm/sec; P < 0.01). Portal hemodynamics do not significantly change in fulminant hepatic failure; therefore, it has no prognostic significance.

The transplantation of human fetal neuroretinal cells in advanced retinitis pigmentosa patients: results of a long-term safety study

The purpose of this study was to determine the long-term safety of transplanting human fetal neuroretinal cells (14 to 18 week gestational age) into a series of patients with advanced retinitis pigmentosa (RP). After obtaining informed consent, both hosts and mothers of donors were screened for transmissible diseases. Pre- and postoperative clinical exams, visual acuity, electroretinograms, and fluorescein angiograms were performed and visual field testing was attempted in each case. Surgically, an anterior approach through pars plana ciliaris was used. A retinotomy was performed in the paramacular area and a two-function cannula was introduced into the subretinal space to deliver a suspension of donor cells. The cell suspension carried approximately 4000 cells/microl; the volume injected did not exceed 150 microl. The patients were examined for periods ranging from 12 to 40 months posttransplantation. To date, no evidence of inflammation, infection, or overt rejection of the graft was noted in the host eye, neither was any change observed in the contralateral, unoperated eye. In conclusion, neuroretinal cells were injected into the subretinal space of 14 patients with advanced RP with no clinical appearance of detrimental effects at the time of surgery or up to 40 months postinjection except in 1 patient who developed retinal detachment. This sets the stage for a phase II clinical trial to determine the possible beneficial effects of this procedure in patients blinded by degenerative retinal disease.

Cryptosporidiosis among cancer patients: an observation

The incidence of cryptosporidiosis was studied in 560 cancer patients presenting with symptoms of diarrhoea. Cryptosporidium oocysts were detected in the stool specimens by modified acid fast staining. Blood was examined for HIV antibodies from patients whose stool specimens were positive for Cryptosporidium oocysts. Oocysts were detected in 7 of the 560 (1.3%) patients who were receiving chemotherapy and had diarrhoea; in five of them the symptoms were acute, while tow patients had chronic diarrhoea. Of these seven patients, five had cancer of haemopoetic system, one had cancer of cervix and one had uterine sarcoma. None of the patients positive for oocysts were positive for HIV antibodies, ruling out the possibility of an opportunistic infection due to HIV infection.

Gram negative bacteria and contact lens induced acute red eye

Two patients using hydrogel contact lenses on a daily wear schedule slept overnight with the lenses and woke up with a Contact Lens Induced Acute Red Eye (CLARE). The contact lenses recovered aseptically at the time of the event grew significant colonies of Pseudomonas aeruginosa and Aeromonas hydrophila in patient A and Pseudomonas aeruginosa and Serratia liquefaciens from patient B. Similar organisms from the contact lenses were recovered from the lens case and lens care solutions of patient B. In both the patients the condition resolved on discontinuation of lens wear. Patient compliance as a requirement for successful contact lens wear is highlighted with the illustration of these cases.

Assessment of suitability & ease of performance of seven commercial assay systems for the detection of antibodies to HIV-1

In this study, we have evaluated the suitability and ease of performance of seven HIV assays namely: Vironostika anti-HIV Uni-Form; Vironostika HIV MIXT; Elavia MIXT; Genelavia MIXT; Serodia-HIV; Immunocomb Bi-spot; and Test pack HIV-1 and 2 Abbott, for use in Indian laboratories. A panel of 41 blind coded Western blot confirmed sera were used for this purpose. Rapid assays like Immunocomb Bi-Spot, Serodia HIV and Test pack HIV-1/HIV-2 Abbott were found to be more suitable and easy to perform as compared to the ELISAs. Sensitivity of all the assays was excellent (100%). Specificity of Serodia HIV, Immunocomb Bi-spot, Test pack HIV-1 and 2 Abbott and Elavia MIXT were excellent (100%), while that of Vironostika MIXT and Vironostika anti-HIV Uni-Form was poor. Positive predictive value of the assays ranged from 64.5 to 100 per cent. Negative predictive value of six of the assays was 100 per cent and that of Vironostika anti-HIV Uni-Form was very poor.

Pathological lesions in HIV positive patients

Pathomorphological features of 10 HIV positive individuals studied at autopsy and biopsy are described. Nine patients had evidence of neuro-AIDS and eight of them succumbed to various opportunistic infections. One surviving patient underwent a diagnostic lymph node biopsy which revealed tuberculous lymphadenopathy. Cryptococcal meningitis was the commonest CNS opportunistic infection, seen in five cases, with disseminated systemic cryptococcosis in two. The other opportunistic infections included toxoplasma encephalitis in two, with acanthamoeba infection in one patient. Pulmonary tuberculosis was noted in three patients while other bacterial infections such as meningococcal meningitis, pseudomonas septicaemia were observed in three and pneumocystis carinii pneumonia in one. One seropositive individual was clinically asymptomatic but succumbed to a road traffic accident. The brain in this case showed features of HIV associated early leucoencephalopathy. Bacterial infections caused by organisms other than Mycobacterium tuberculosis associated with AIDS are often underdiagnosed and should be considered, especially in developing countries. In cases of cryptococcal and tuberculous meningitis or multiple parasitic infections, the patients should be screened for associated HIV infection.

The role of immunological & virological techniques in the diagnosis of herpes simplex encephalitis

The efficacy of immunological and virological methods in the diagnosis of herpes simplex encephalitis (HSE) was studied in 22 patients diagnosed as HSE by clinical, radiological EEG parameters. CSF cell counts were elevated in 14 of 18 patients with a lymphocytic predominance in 13. Virus specific IgG antibody detection by ELISA in paired CSF samples was possible in 8 of 17 patients. HSV antigen could be detected by immunohistochemical methods in the cells of the CSF and/or brain tissue in 7 of 9 patients. In four of them antemortem diagnosis was possible facilitating prompt specific antiviral therapy. Virus isolation was possible in 2 of 8 patients, one from brain biopsy tissue and the other from brain tissue obtained at autopsy. Using all the three methods, the diagnosis of HSE could be confirmed in 14 of 22 (63.6%) patients.

Development of Atlantic Salmon (Salmo salar) Eggs and Alevins Under Varied Temperature Regimes

Atlantic salmon (Salmo salar) eggs and alevins were raised under conditions where the temperature was systematically varied either at fertilization, at the eyed egg stage, or at hatching. Mortality was more than 20% in eggs started immediately after fertilization at constant incubation temperatures < 4 °C as compared with 5% or less at temperatures > 4 °C. Alevins that eyed at 8 °C and higher were progressively smaller the higher the temperature. The optimum temperature from fertilization to eye pigmentation was near 6 °C. Eyed eggs reared at lower temperatures until hatching were larger than those hatched at higher temperatures. This size differential was maintained until the yolk was completely absorbed at all posthatching temperatures investigated. Sudden decreases in temperature at the eyed egg and hatching stages induced severe edema of the alevin yolk sac, resulting in slower growth and increased mortality.

Factors Affecting Winter Respiration in Ontario Lakes

Winter oxygen consumption was measured in 16 Ontario lakes. Whole lake respiration ranged from 0.08 to 0.39 g O2 m−2 day−1 and was positively correlated with mean depth, phosphorus m−2 at spring overturn, and summer chlorophyll a m−2. Morphological variables plus Secchi depth were explained over 80% of the variability in respiration rates.