Late toxicity after post-prostatectomy intensity modulated radiation therapy: Evaluating normal-tissue sparing guidelines

Purpose

Dose-volume histogram (DVH) toxicity relationships are poorly defined in men who receive radiation after radical prostatectomy (RP). We evaluated Radiation Therapy Oncology Group (RTOG) study 0534 and institutional intact normal-tissue sparing guidelines, as well as dose to bladder trigone, for ability to minimize late toxicity.

Methods and materials

164 men received intensity modulated radiation therapy (RT) to a median prostate bed dose of 66.6 Gy at a median of 22 months after RP. 46% of men were prescribed androgen deprivation therapy and pelvic lymph node irradiation to a median dose of 50.4 Gy. DVH relationships for the rectum, bladder, trigone, and bladder excluding the clinical target volume (bladder-CTV) were analyzed against the Common Terminology Criteria for Adverse Events late grade 2 + (G2+) gastrointestinal (GI) and genitourinary (GU) toxicity by log-rank test. RTOG 0534 (rectum V65, 40 Gy ≤35, 55%, and bladder-CTV V65, 40 ≤50, 70%) and intact prostate RT institutional guidelines (rectum V70, 65, 40 ≤20, 40, 80% and bladder V70, 65, 40 ≤30, 60, 80%, respectively) guidelines were evaluated.

Results

With a median follow-up time of of 33 months, the 4-year freedom from G2 + GI and GU toxicity were both 91%. G2 + GI (n = 12) and GU (n = 15) toxicity included 4% diarrhea (n = 6), 4% hemorrhage (n = 6), 1% proctitis (n = 1), and 4% urinary frequency (n = 7), 1% obstructive (n = 2), 2% cystitis (n = 3), and 3% incontinence (n = 5), respectively. RTOG 0534 rectum and bladder goals were not achieved in 65% and 41% of cases, while the institutional intact prostate goals were not achieved in 21% and 25% of cases, respectively. Neither dose to the bladder trigone nor any of the proposed normal tissue goals were associated with late toxicity (P > .1). In the univariate analysis, age, pelvic RT, RT dose, anticoagulation use, androgen deprivation therapy, time from RP to RT, and tobacco history were not associated with toxicity.

Conclusions

More than 90% of men were free from late G2 + toxicity 4 years after post-RP intensity modulated RT. No tested parameters were associated with late toxicity. In the absence of established normal-tissue DVH guidelines in the postoperative setting, the use of intact guidelines is reasonable.

Clinical and molecular markers of long-term survival after oligometastasis-directed stereotactic body radiotherapy (SBRT)

BACKGROUND

The selection of patients for oligometastasis-directed ablative therapy remains a challenge. The authors report on clinical and molecular predictors of survival from a stereotactic body radiotherapy (SBRT) dose-escalation trial for oligometastases.

METHODS

Patients who had from 1 to 5 metastases, a life expectancy of >3 months, and a Karnofsky performance status of >60 received escalating SBRT doses to all known cancer sites. Time to progression, progression-free survival, and overall survival (OS) were calculated at the completion of SBRT, and clinical predictors of OS were modeled. Primary tumor microRNA expression was analyzed to identify molecular predictors of OS.

RESULTS

Sixty-one evaluable patients were enrolled from 2004 to 2009. The median follow-up was 2.3 years for all patients (range, 0.2-9.3 years) and 6.8 years for survivors (range, 2.0-9.3 years). The median, 2-year, and 5-year estimated OS were 2.4 years, 57%, and 32%, respectively. The rate of progression after SBRT was associated with an increased risk of death (hazard ratio [HR], 1.44; 95% confidence interval [CI], 1.24-1.82). The time from initial cancer diagnosis to metastasis (HR, 0.98; 95% CI, 0.98-0.99), the time from metastasis to SBRT (HR, 0.98; 95% CI, 0.98-0.99), and breast cancer histology (HR, 0.12; 95% CI, 0.07-0.37) were significant predictors of OS. In an exploratory analysis, a candidate classifier using expression levels of 3 microRNAs (miR-23b, miR-449a, and miR-449b) predicted survival among 17 patients who had primary tumor microRNA expression data available.

CONCLUSIONS

A subset of oligometastatic patients achieves long-term survival after metastasis-directed SBRT. Clinical features and primary tumor microRNA expression profiling, if validated in an independent dataset, may help select oligometastatic patients most likely to benefit from metastasis-directed therapy. Cancer 2016;122:2242-50. © 2016 American Cancer Society.

Applications of Hairpin DNA-Functionalized Gold Nanoparticles for Imaging mRNA in Living Cells

Molecular imaging agents are useful for imaging molecular processes in living systems in order to elucidate the function of molecular mediators in health and disease. Here, we demonstrate a technique for the synthesis, characterization, and application of hairpin DNA-functionalized gold nanoparticles (hAuNPs) as fluorescent hybridization probes for imaging mRNA expression and spatiotemporal dynamics in living cells. These imaging probes feature gold colloids linked to fluorophores via engineered oligonucleotides to resemble a molecular beacon in which the gold colloid serves as the fluorescence quencher in a fluorescence resonance energy transfer system. Target-specific hybridization of the hairpin oligonucleotide enables fluorescence de-quenching and subsequent emission with high signal to noise ratios. hAuNPs exhibit high specificity without adverse toxicity or the need for transfection reagents. Furthermore, tunability of hAuNP emission profiles by selection of spectrally distinct fluorophores enables multiplexed mRNA imaging applications. Therefore, hAuNPs are promising tools for imaging gene expression in living cells. As a representative application of this technology, we discuss the design and applications of hAuNP targeted against distinct matrix metalloproteinase enzymes for the multiplexed detection of mRNA expression in live breast cancer cells using flow cytometry and fluorescence microscopy.

Neonatal bartter syndrome

We report a case of neonatal Bartter syndrome in a 31 weeks premature baby girl with antenatal unexplained polyhydramnios requiring amnioreduction. She presented with early onset E. coli septicaemia and severe dehydration leading to pre-renal renal impairment which obscure the typical biochemical changes of hypokalaemic hypochloraemic metabolic alkalosis.

Physicians' beliefs about the benefits and risks of adjuvant therapies for stage II and stage III colorectal cancer

BACKGROUND

Adjuvant therapy plays a major role in treating colorectal cancer, and physicians' views of its effectiveness influence treatment decisions. We assessed physicians' views of the relative benefits and risks of adjuvant chemotherapy and radiotherapy for stages II and III colon and rectal cancers.

METHODS

The Cancer Care Outcomes Research and Surveillance Consortium surveyed a geographically dispersed population of medical oncologists, radiation oncologists, and surgeons in the United States about the benefits and risks of adjuvant therapies for colorectal cancer. We used logistic regression to assess the association of physician and practice characteristics with beliefs about adjuvant therapies.

RESULTS

Among 1,296 respondents, > 90% believed the benefits of adjuvant therapies for stage III colorectal cancer outweigh the risks. Only 21.9%, 50%, and 50.4% believed in the net benefit of chemotherapy for stage II colon cancer, chemotherapy for stage II rectal cancer, and radiation for stage II rectal cancer, respectively. Younger physicians were less likely than others to perceive adjuvant therapy for stage II colorectal cancer as beneficial. Medical oncologists were more likely than surgeons and radiation oncologists to endorse the benefits of adjuvant chemotherapy and radiation for stage II rectal cancer, but less likely for stage II colon cancer.

CONCLUSIONS

Physicians largely agreed that the benefits of adjuvant chemotherapy for stage III colon cancer, as well as chemotherapy, and radiation for stage III rectal cancer, outweigh the risks, consistent with strong evidence, but were divided over the net benefit of adjuvant therapies for stage II colorectal cancer, where evidence is inconsistent.

Oesophageal intubation and ventilation as initial airway support of newborn infant with tracheal agenesis

Tracheal agenesis is a rare congenital airway anomaly which presents as an airway emergency at birth. We report a case of late premature Chinese infant with tracheal agenesis type II (by Floyd's classification) who presented with severe respiratory distress at birth. He had multiple failed attempts at intubations with accidental oesophageal intubation and ventilation. Tracheal agenesis with tracheo-oesophageal fistula was suspected from an emergency optical laryngoesophagoscopy done. The infant was subsequently stabilized on oesophageal ventilation. The diagnosis was confirmed on CT scan and parents were counseled regarding the poor outcome and decided for withdrawal at day 7 of life.

A novel method for accurate and reproducible functional cup positioning in total hip arthroplasty

Cup positioning is an important variable for short and long term function, stability, and durability of total hip arthroplasty (THA). This novel method utilizes internal and external bony landmarks, and the transverse acetabular ligament for positioning the acetabular component. The cup is placed parallel and superior to the transverse ligament and inside the anterior wall notch of the true acetabulum, then adjusted for femoral version and pelvic tilt and obliquity based on weight bearing radiographs. In 78 consecutive THAs, the mean functional anteversion and abduction angles were 17.9° ± 4.7° and 41.7° ± 3.8°, respectively. 96% of the functional anteversion measurements and 100% of the functional abduction angles were within the safe zone. This technique is an easy, reproducible, and accurate method for functional cup placement.

Pain management after total knee arthroplasty using a multimodal approach

Improvements in pain management techniques over the past decade have had a significant impact on the outcomes of total knee arthroplasty. Of these techniques, multimodal approaches have shown potential. The purpose of this study was to compare the results of periarticular injection (PAI) to a combination of patient-controlled epidural analgesia and femoral nerve block (PCEA/FNB). Ninety patients undergoing primary unilateral total knee arthroplasty between June 2010 and March 2011 were randomized into 2 groups. The first group received the PCEA/FNB protocol, whereas the second group received the PAI. Mean patient age was 66.1 ± 8.7 years. All patients were operated on using a similar standard medial parapatellar approach, and all received preemptive analgesia and postoperative pain protocols. All patients were interviewed twice daily for the first 3 days postoperatively, once on day 7, and once in month 6. The 2 groups had similar readiness for discharge (PCEA/FNB group, 3.3 ± 1.2 days; PAI group, 3.2 ± 1.9 days). The results indicated no statistical difference between the 2 groups in 3 of 4 categories (rest in the morning, rest in the evening, and ambulation in the morning). Pain on ambulation was the only category that was statistically lower in the PCEA/FNB group than in the PAI group.Although the study demonstrates similar results between the 2 groups, PAI can play a major role in postoperative pain control in institutions that may not have appropriately trained individuals, equipment, and resources for PCEA/FNB. It also reduces many of the side effects and complications associated with regional anesthesia.

A shared structural solution for neutralizing ebolaviruses

Sudan virus (genus Ebolavirus) is lethal, yet no monoclonal antibody is known to neutralize it. We here describe antibody 16F6 that neutralizes Sudan virus and present its structure bound to the trimeric viral glycoprotein. Unexpectedly, the 16F6 epitope overlaps that of KZ52, the only other antibody against the GP(1,2) core to be visualized to date. Furthermore, both antibodies against this crucial epitope bridging GP1-GP2 neutralize at a post-internalization step--probably fusion.

Cystoid macular oedema and changes in retinal thickness after phacoemulsification with optical coherence tomography

AIMS

To study the incidence of cystoid macular oedema and changes in retinal thickness after phacoemulsification with optical coherence tomography (OCT).

METHODS

In all, 131 eyes of 131 patients were studied at the ophthalmology clinic at Tung Wah Eastern Hospital from September 2001 to October 2002. All the patients had clinical assessment and OCT preoperatively and at weeks 2, 4, and 8 postoperatively. The incidence of postoperative cystoid macular oedema (CMO) was evaluated. The foveal thickness (FT) and central 1 mm retinal thickness (CT) at different time intervals were analysed.

RESULTS

Four (3.05%) patients developed CMO after phacoemulsification, which was evident clinically and tomographically. Fluorescein angiogram confirmed leakage in all cases. For other patients, the mean preoperative FT was 189.36 +/- 26.83 microm. The mean FT, were 175.74 +/- 26.79 microm, 180.25 +/- 27.13 microm, 176.58 +/- 26.45 microm at 2 weeks, 4 weeks, and 8 weeks postoperatively, respectively. The preoperative FT was significantly thicker than those in the postoperative period. The same trend was noted for CT.

CONCLUSION

OCT is useful for detecting and confirming clinical CMO after cataract surgery; however, its use in detecting subtle changes in retinal thickness is limited by the normal variation in retinal thickness. The measurement of retinal thickness with OCT may also be affected by the status of the lens.

Dense medium plasma environments: a new approach for the disinfection of water

The levels to which microbial colony forming units are permitted in various waters fit for human contact are carefully regulated. Conventional chemical and physical approaches usually are complex processes with significant limitations due to the generation of toxic side-products. In this contribution a novel plasma reactor--dense medium plasma reactor--is described, and its efficiency for the disinfection of contaminated water is discussed. It has been shown that owing to the intense stirring of the reaction medium (e.g. contaminated water), as a result of the specially designed spinning electrode and gas-flow system, a volume-character discharge is created, which can efficiently kill bacteria. It has been demonstrated that treatment times as low as 20 s are enough for the total inactivation of microorganisms for 200 mL of 10(5) bacteria/mL contaminated water.

Biofilm formation and contamination of cheese by nonstarter lactic acid bacteria in the dairy environment

Defects in cheese, such as undesirable flavors, gas formation, or white surface haze from calcium lactate crystals, can result from growth of nonstarter lactic acid bacteria (NSLAB). The potential for biofilm formation by NSLAB during cheese manufacturing, the effect of cleaning and sanitizing on the biofilm, and bacterial growth and formation of defects during ripening of the contaminated cheese were studied. Stirred-curd Cheddar cheese was made in the presence of stainless steel chips containing biofilms of either of two strains of erythromycin-resistant NSLAB (Lactobacillus curvatus strain JBL2126 or Lactobacillus fermentum strain AWL4001). During ripening, the cheese was assayed for total lactic acid bacteria, numbers of NSLAB, and percentage of lactic acid isomers. Biofilms of L. curvatus formed during cheese making survived the cleaning process and persisted in a subsequent batch of cheese. The starter culture also survived the cleaning process. Additionally, L. curvatus biofilms present in the vat dislodged, grew to high numbers, and caused a calcium lactate white haze defect in cheese during ripening. On the other hand, biofilms of L. fermentum sloughed off during cheese making but could not compete with other NSLAB present in cheese during ripening. Pulsed-field gel electrophoresis results verified the presence of the two biofilm strains during cheese making and in the ripening cheese. Probable contamination sites in the plant for other NSLAB isolated in the cheese were identified, thus supporting the hypothesis that resident NSLAB biofilms are a viable source of contamination in the dairy environment.

On the behavioral significance of head direction cells: neural and behavioral dynamics during spatial memory tasks

Current theories assume that rats use the directional information reflected by head direction (HD) cells when performing spatial tasks. This assumption was assessed by monitoring anterior thalamic HD cell activity and relating it to the subject's behavioral response on 2 spatial memory tasks that tested either reference memory or working memory. In both tasks, there was a significant number of trials where there was not a tight coupling between the preferred firing direction of HD cells and the direction of the behavioral response. In addition, it was possible to intentionally change the preferred direction of HD cells without affecting performance accuracy. An additional experiment showed that manipulations that affected internal, but not external, cues impaired performance on the reference memory task. These findings suggest that HD cell activity was not consistently guiding the subjects' behavior on these 2 spatial tasks.

Modulation of steroidogenesis by selenium in a novel adrenal cell line developed using targeted tumorigenesis

Glutathione peroxidase (GPx-1) is a selenoenzyme that metabolizes H(2)O(2), a source of potentially toxic free radicals. Steroidogenesis is markedly inhibited by H(2)O(2) in vitro.

OBJECTIVE

to study the effects of selenium deficiency on GPx activity and adrenal steroidogenesis in a novel adrenal cell line developed using targeted tumorigenesis.

METHODS

AN4Rppc7 cells were grown for 7 days in serum-free medium. 8-Br-cAMP-stimulated concentrations of steroid hormones were measured by RIA. StAR (Steroid Acute Reactive Protein) mRNA was measured by Northern blot.

RESULTS

selenium deficiency caused a 99% There was a 51%, progesterone, corticosterone and aldosterone production, respectively (p<0.05 by ANOVA). StAR mRNA was not affected by selenium.

CONCLUSIONS

selenium deficiency causes a marked decrease in GPx activity. Decreased steroid hormone production occurs for selenium concentrations equal or lower than 5 nM. The absence of changes in StAR mRNA content suggests that selenium deficiency does not affect cholesterol access to the mitochondria.

Evidence for contribution of tripartite hemolysin BL, phosphatidylcholine-preferring phospholipase C, and collagenase to virulence of Bacillus cereus endophthalmitis

Bacillus cereus causes a highly fulminant endophthalmitis which usually results in blindness. We previously concluded that hemolysin BL (HBL), a tripartite necrotizing pore-forming toxin, is a probable endophthalmitis virulence factor because it is highly toxic to retinal tissue in vitro and in vivo. We also determined that B. cereus produces additional retinal toxins that might contribute to virulence. Here we fractionated crude B. cereus culture supernatant by anion-exchange chromatography and found that in vitro retinal toxicity was also associated with phosphatidylcholine-preferring phospholipase C (PC-PLC). The pure enzyme also caused retinal necrosis in vivo. We showed that phosphatidylinositol-specific PLC and sphingomyelinase were nontoxic and that two hemolysins, cereolysin O and a novel hemolysin designated hemolysin IV, were marginally toxic in vitro. The histopathology of experimental septic endophthalmitis in rabbits mimicked the pathology produced by pure HBL, and both HBL and PC-PLC were detected at toxic concentrations in infected vitreous fluid. Bacterial cells were first seen associated with the posterior margin of the lens and eventually were located throughout the lens cortex. Detection of collagenase in the vitreous humor suggested that infiltration was facilitated by the breakdown of the protective collagen lens capsule by that enzyme. This work supports our conclusion that HBL contributes to B. cereus virulence and implicates PC-PLC and collagenase as additional virulence factors.

Heterogeneity observed in the components of hemolysin BL, an enterotoxin produced by Bacillus cereus

Hemolysin BL (HBL), a diarrheal enterotoxin originally isolated from Bacillus cereus strain F837/76, is composed of three antigenically distinct proteins designated B, L1, and L2. All three components are required for biological activity. Here, we report antigenic and physical variations in HBL components produced by other B. cereus isolates. Reactions of partial identity were observed in double gel immunodiffusion assays using antibodies to highly purified B, L1, and L2 components of F837/76 and culture supernatants of strains F837/76 and S1C. Western blot analysis showed that F837/76 produced one 38-kDa B protein, one 38-kDa L1, and one 43-kDa L1 protein. In strain S1C, two B (38 and 42 kDa), two L1 (38 and 41 kDa), and one L1 (43 kDa) proteins were detected. Further Western blot analysis of 127 B. cereus isolates showed that 90 produced one or more of the three HBL components. Approximately half of these 90 isolates (43/90; 48%) produced protein profiles which differed from that of F837/76. A total of four B, two L1, and three L2 component profiles with proteins of different sizes were observed. Individual strains produced various combinations of single or multiple bands of each component. In addition, some strains produced only one or two of the three HBL components. The public health significance of these strains is unknown, as all three components are required for biological activity. The data presented here demonstrates a high degree of heterogeneity in HBL and provide the basis for further studies to characterize the variations in HBL and to determine the role of the variant components in pathogenicity.

Position effect of human telomeric repeats on replication timing

Telomeres are distinct structures, composed of short, repeated sequences, at the ends of all eukaryotic chromosomes. Telomeres have been shown in yeast to induce late replication in S phase and to silence transcription of neighboring genes. To examine the possibility of similar effects in human chromosomes, we studied cells from a subject with a microdeletion of 130 kb at the end of one copy of chromosome arm 22q, repaired by the addition of telomere repeats. Using fluorescence in situ hybridization of S phase nuclei, a distinct difference was found in the replication timing of the breakpoint region between the intact and truncated copies of chromosome 22. This difference was evident as a shift from middle to late replication time of the breakpoint region adjacent to the repaired telomere. This finding suggests that the human telomere sequence influences activation of adjacent replication origin(s). The difference in replication timing between the two chromosomes was not associated with differences in sensitivity to digestion by DNase I or with methylation of regions immediately adjacent to the breakpoint. Furthermore, both alleles of arylsulfatase A, a gene located at a distance of approximately 54 kb from the breakpoint, were expressed. We conclude that as in yeast, the proximity of telomeric DNA may induce a positional effect that delays the replication of adjacent chromosomal regions in humans.

Two novel human RAB genes with near identical sequence each map to a telomere-associated region: the subtelomeric region of 22q13.3 and the ancestral telomere band 2q13

Two closely related genes have been identified at 2q13 and 22q13.3. These genes show similarity to members of the RAB family of small GTPases. RABL2A and RABL2B differ by three conservative amino acid changes over a total of 228 residues. Both are expressed in all tissues tested. Northern analysis showed that a 2.5-kb transcript is expressed in all tissues tested while a 1.4-kb transcript is specifically expressed only in muscle. The size difference between these two transcripts is the result of differential splicing of an intron within the 3' UTR. RABL2B is located within the subtelomeric region of 22q13.3. RABL2A maps to 2q13, the site of an ancestral telomere fusion event, suggesting that it also may be a subtelomeric gene.

D1- and D2-like dopamine receptors are co-localized on the presynaptic varicosities of striatal and nucleus accumbens neurons in vitro

The neuromodulatory actions of dopamine in the striatum and nucleus accumbens are likely to depend on the distribution of dopamine receptors on individual postsynaptic cells. To address this, we have visualized D1- and D2-like receptors on living medium-spiny GABAergic neurons in cultures from the striatum and nucleus accumbens using receptor antagonist fluoroprobes. We labeled D1-like receptors with rhodamine-SCH23390, D2-like receptors with rhodamine-N-(p-aminophenethyl)spiperone and synaptic sites with K+-stimulated uptake of the activity-dependent endocytic tracer FM-143. The fluoroprobes were applied in sequence to assess co-localization. We found that D1- or D2-like receptors were present on about two-thirds of the cells, and co-localized on 22+/-3% (mean +/- S.E.M.) of striatal and 38+/-6% of nucleus accumbens cells. On either D1 or D2 labeled cells, postsynaptic labeling continuously outlined the cell body membrane and extended to proximal dendrites, but not axons. About two-thirds of synaptic varicosities showed D1 or D2 labeling. D1- and D2-like receptors were co-localized on 21+/-4% of striatal and 27+/-3% of nucleus accumbens varicosities. Presynaptic labeling was typically more intense than postsynaptic labeling. The distribution of presynaptic dopamine receptors contrasted with that of postsynaptic GABA(A) receptors, which were clustered in longer patches on neighboring postsynaptic membranes. The extensive presence of D1- and D2-like receptors on presynaptic varicosities of medium-spiny neurons suggests that the receptors are likely to play an important and interacting role in the presynaptic modulation of inhibitory synaptic transmission in the striatum and nucleus accumbens. The significant overlap in labeling suggests that D1-D2 interactions, which occur at the level of individual postsynaptic cells, the circuit level and the systems level, may also be mediated at the presynaptic level. Finally, the ability to visualize dopamine, as well as GABA(A), receptors on the individual synapses of living neurons now makes possible physiological studies of individual mesolimbic system synapses with known receptor expression.

Biofilms in food processing environments

Biofilms are a constant concern in food processing environments. Our overall research focus has been to understand the interaction of factors affecting bacterial attachment and biofilm formation with the ultimate goal of devising strategies to control this problem. This paper briefly describes three areas of biofilm research in which we have been involved. Listeria monocytogenes, a foodborne pathogen, survived for prolonged periods on stainless steel and buna-n rubber, materials commonly used in food-processing equipment. Survival was affected by temperature, relative humidity, attachment surface, and soil. Some components in the rubber inhibited growth of the organism on buna-n, which also affected the efficacy of sanitizers on biofilm inactivation. In cheese manufacture, biofilms of Lactobacillus curvatus could lead to a defect caused by the formation of calcium lactate crystals in Cheddar cheese. This hardy organism persisted in low numbers on equipment surfaces and was difficult to eradicate. We investigated the relative contributions and interactions of mechanical, thermal, and chemical processes in an air-injected clean-in-place method for milking systems. Overall, it is important to study the interactions between bacteria and the surfaces in a specific food processing environment to provide more effective measures for prevention of biofilm formation and for its removal.

Attachment of Escherichia coli O157:H7 in ground beef to meat grinders and survival after sanitation with chlorine and peroxyacetic acid

The potential for transfer of Escherichia coli O157:H7 from contaminated ground beef to grinding equipment and the inactivation of attached cells during cleaning and sanitizing was examined. Chub-packed ground beef with lean:fat ratios of 75:25, 80:20 or 90:10 was inoculated with 6 log CFU/g or 2 log CFU/g E. coli O157:H7 strain FRIK 910. Samples were consecutively ground in a Hobart meat grinder with stainless steel (SS) chips (1 cm2) glued to the auger housing. Chips were harvested after grinding, detergent washing with or without manual scrubbing and rinsing, sanitizing in a chlorine or peroxyacetic acid sanitizer, and overnight storage. Survival of E. coli O157:H7 was evaluated both by plate count and enrichment in trypticase soy broth. Approximately 3 to 4 log CFU/cm2 were attached to the SS after grinding with all three fat contents. After washing and sanitizing in a chlorine or peroxyacetic acid sanitizer, viable bacteria were infrequently recovered by plate count. Enrichment of chips resulted in a higher survival rate with both sanitizing treatments, indicating that cell numbers below the limit of detection (5 CFU/cm2) or potentially injured organisms remained on the surface. Manual scrubbing during the washing step reduced the recovery rate. The scrubbing step also increased the number of passing scores assigned using an ATP bioluminescence assay of total residual soil on the chips sanitized in chlorine. The overall results indicate that plate counts alone may not be a reliable indicator of sanitation efficacy and may be validated by enrichment assay.

Production of staphylococcal enterotoxin H under controlled pH and aeration

The effects of controlled pH and aeration on the growth of Staphylococcus aureus strain FRI-569 and production of enterotoxin H (SEH) were studied. S. aureus FRI-569 did not grow well anaerobically. Aeration permitted better growth of cells especially at a flow rate of 300 cc/min. The optimal pH for S. aureus FRI-569 growth was 7.0, with less growth being observed at pH 6.5 and 7.5 or with no pH control. Very little SEH (< 21 ng/ml) was produced by S. aureus strain FRI-569 under anaerobic incubation. High SEH production was observed with aeration at 300 cc/min. Increasing aeration to 400 cc/min or decreasing it to 200 cc/min resulted in reduced SEH production. Larger amounts of SEH were produced when the pH was controlled at 7.0, while maintaining the pH at 6.5 or 7.5 resulted in lower levels of SEH being produced. However, the amounts were still greater than those observed when the pH was not controlled.