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Background Preoperative (neoadjuvant) chemotherapy and radiotherapy are more effective than similar postoperative treatment for oesophageal, gastric, and rectal cancers, perhaps because of more effective micrometastasis eradication and reduced risk of incomplete excision and tumour cell shedding during surgery. The FOxTROT trial aims to investigate the feasibility, safety, and efficacy of preoperative chemotherapy for colon cancer. Methods In the pilot stage of this randomised controlled trial, 150 patients with radiologically staged locally advanced (T3 with >= 5 mm invasion beyond the muscularis propria or T4) tumours from 35 UK centres were randomly assigned (2:1) to preoperative (three cycles of OxMdG [oxaliplatin 85 mg/m(2), l-folinic acid 175 mg, fluorouracil 400 mg/m(2) bolus, then 2400 mg/m(2) by 46 h infusion] repeated at 2-weekly intervals followed by surgery and a further nine cycles of OxMdG) or standard postoperative chemotherapy (12 cycles of OxMdG). Patients with KRAS wild-type tumours were randomly assigned (1:1) to receive panitumumab (6 mg/kg; every 2 weeks with the first 6 weeks of chemotherapy) or not. Treatment allocation was through a central randomisation service using a minimised randomisation procedure including age, radiological T and N stage, site of tumour, and presence of defunctioning colostomy as stratification variables. Primary outcome measures of the pilot phase were feasibility, safety, and tolerance of preoperative therapy, and accuracy of radiological staging. Analysis was by intention to treat. This trial is registered, number ISRCTN 87163246. Findings 96% (95 of 99) of patients started and 89% (85 of 95) completed preoperative chemotherapy with grade 3-4 gastrointestinal toxicity in 7% (seven of 94) of patients. All 99 tumours in the preoperative group were resected, with no significant differences in postoperative morbidity between the preoperative and control groups: 14% (14 of 99) versus 12% (six of 51) had complications prolonging hospital stay (p=0.81). 98% (50 of 51) of postoperative chemotherapy patients had T3 or more advanced tumours confirmed at post-resection pathology compared with 91% (90 of 99) of patients following preoperative chemotherapy (p=0.10). Preoperative therapy resulted in significant downstaging of TNM5 compared with the postoperative group (p=0.04), including two pathological complete responses, apical node involvement (1% [one of 98] vs 20% [ten of 50], p

The effect of abomasal fructo-oligosaccharides supplementation on sheep faecal microbiota was investigated in a balanced, two Latin square, cross-over design experiment. Ten fistulated sheep were managed in five consecutive periods, with each of five treatments (an ‘acidified saline’ control or one of four prebiotic candidates chosen to represent different types of oligosaccharides: Arabinogalactan, Fibruline, Raftilose, or Yacon) administered to two sheep in each period. Seven grams of fructo-oligosaccharides were used daily for each animal. In each period, fresh faecal samples were collected before, during and after ‘supplementation’ for the analysis of bifidobacteria, lactobacilli, Escherichia coli, sulphite-reducing clostridia, total anaerobes, pH and dry matter. The treatments with Fibruline, Raftilose and Yacon increased the sheep faecal bifidobacteria after 9 days of daily dosing. Compared with the control, the Raftilose treatment caused the greatest increase by 2.128 log10 CFU/g of faeces...

Recovery of nisin from minced meat and meat emulsions was poor and variable. The rate of recovery was little affected by the presence of NaCl and/or NaNO2, particle size, or the meat to extractant (0.02N HCl) ratio, but was significantly affected by the fat content of the meat. For nisin added at 100 iu/g, recoveries at the optimal meat to extractant ratio, 10% wt/wt suspension, ranged from 26% at 3% fat to 76% at 83% fat. At addition levels of 200 iu/g and greater, nisin recovery efficiency was reduced.

Aims: To identify the abattoir source(s) of psychrophilic clostridia causing ‘blown pack’ spoilage of vacuum-packed chilled meats. Methods and Results: Molecular procedures were used to detect the presence of specific 16S rRNA gene fragments of blown pack-causing clostridia in samples collected from a commercial abattoir and its environs. Blown pack-causing clostridia were consistently detected in hide, soil and faecal samples, as well as in samples collected at slaughter plant locations associated with handling of animals and animal carcasses prior to pelt removal. Conclusions: The data indicate that pelts per se or soil particles/faecal material attached thereto are the most probable primary reservoir of blown pack clostridia in the abattoir. Significance and Impact of the Study: The paper provides information critical for controlling blown pack spoilage in commercial meat-processing plants.

Aims: To develop a practical molecular procedure that directly, without isolation, and specifically detects the presence of clostridia which cause ‘blown pack’ spoilage of vacuum-packed meat. Methods and Results: Primer sets and PCR amplification procedures were developed that detect the presence of 16S rDNA gene and/or 16S-23S rDNA internal transcribed spacer fragments of ‘blown pack’ causing clostridia in meat. The specificity of the developed procedures was evaluated with DNA obtained from close phylogenetic neighbours of ‘blown pack’ causing clostridia, food clostridia and common meat spoilage microorganisms. The sensitivity of detection was assessed in non-enriched and low-temperature-enriched beef mince inoculated with serially diluted pure cultures of Clostridium estertheticum DSMZ 8809T and Cl. gasigenes DB1AT . The efficacy of detection procedures was evaluated for naturally contaminated vacuum-packed meat samples. Three primer sets, 16SE, 16SDB and EISR, produced amplicons of the expected size with DNA templates from target clostridia, but failed to yield PCR products with DNAs from any other microorganisms tested. With 16SE and 16SDB primers, minimum levels of detection were 104 CFU g−1 for non-enriched, and 102 CFU g−1 for enriched meat samples. Based on the established specificity of these primers, as well as DNA sequencing of amplicons, Cl. gasigenes was confirmed as the causative agent of ‘blown pack’ spoilage in two packs, and Cl. estertheticum as the causative agent in the third. Conclusions: The developed method can be used for rapid detection of ‘blown pack’ causing clostridia in commercial blown packs, or following low temperature enrichment, for detection of these microorganisms in meat containing as few as 100 clostridial cells per gram. Significance and Impact of the Study: The paper reports practical procedures that can be used for rapid confirmation of the causative agents of clostridial ‘blown pack’ spoilage in commercial spoiled packs, or for detection of psychrophilic clostridia in epidemiological trace back of ‘blown pack’ spoilage incidents in meat processing plants.

Aims: To identify the abattoir source(s) of culturable psychrophilic clostridia causing ‘blown pack’ spoilage of vacuum-packed chilled meats. Methods and Results: Psychrophilic and psychrotolerant clostridia were isolated from hides, faeces and tonsils of deer slaughter stock, and from a meat plant environment. The isolates were differentiated using restriction fragment length polymorphism analysis of the 16S rDNA gene (PCR–RFLP) and 16S-23S rDNA internal transcribed spacer (ITS) analysis. PCR–RFLP group I clostridia were found to have restriction patterns indistinguishable from the patterns of ‘blown pack’-causing Clostridium gasigenes DB1AT and R26. Gas production in packs inoculated with vegetative cells of PCR–RFLP group I clostridia was first evident after 14 days at 2 °C. The prevalence of these clostridia was similar in hide and faecal samples from slaughter animals, but these micro-organisms were absent from tonsils and the meat plant environment. Banding patterns of PCR–RFLP group II clostridia showed some cross-similarity with patterns of the ‘blown pack’-causing micro-organism Cl. estertheticum DSM 8809T and Cl. estertheticum-like meat strains. The majority of clostridia in PCR–RFLP group II were found in the faeces of slaughter animals. Isolates representing PCR–RFLP group II did not, however, produce gas in vacuum packs stored at 2 °C for 84 days. Conclusions: The data suggest that soil particles attached to hide or present in faeces are the most probable primary reservoir from which ‘blown pack’ clostridia are introduced onto carcasses. Therefore, dressing procedure hygiene remains paramount in order to control the spread of psychrophilic Clostridium spp. in a meat plant. Significance and Impact of the Study: The paper provides information critical for controlling ‘blown pack’ spoilage in meat processing plants. It reports on the use of molecular techniques for determination of abattoir sources of ‘blown pack’-causing clostridia.

Aims: To develop a practical molecular procedure that directly (without isolation) and specifically detects the presence of clostridia, which cause the deep tissue spoilage condition . Methods and Results: A primer set was designed and a PCR amplification procedure developed to detect the presence of Clostridium algidicarnis and Cl. putrefaciens 16S rDNA gene fragments in meat. The procedure yielded amplicons of the expected size with homologous DNA templates, but failed to give PCR products with DNAs from 47 food clostridia and common meat spoilage micro-organisms. The minimum level of detection was 104 cfu g−1 for nonenriched meat samples. Based on the established specificity of these primers, as well as DNA sequencing of amplicons, the presence of Cl. algidicarnis and/or Cl. putrefaciens was confirmed in a swab sample taken from the cartilage of an ovine stifle joint, which on opening exhibited strong offensive odours. Conclusions: The developed method can be used for rapid detection of clostridia causing deep tissue spoilage in commercial vacuum packs. Significance and Impact of the Study: The paper reports practical procedures that can be used for rapid confirmation of the causative agents of deep tissue clostridial spoilage in commercial vacuum-packed chilled meats.

D.M. BRODA, D.R. MUSGRAVE and R.G. BELL.2000. Reference and meat strains of psychrophilic and psychrotrophic clostridia were differentiated using restriction fragment length polymorphism (RFLP) analysis of genomic DNA (DNA-RFLP) and the polymerase chain reaction—amplified 16S rDNA gene (PCR-RFLP). Groupings obtained with PCR-RFLP were confirmed with 16S rDNA gene sequencing. DNA-RFLP resolved 19 of the 22 meat strains into 11 groups. Three meat strains were untypable using this method. All reference strains representing different genotypic species could be distinguished by the restriction patterns of 16S rDNA genes. With PCR-RFLP, the 22 meat strains produced eight distinct genotypes. 16S rDNA gene sequencing confirmed that each genotype was represented by a distinct sequence. PCR-RFLP restriction patterns of 15 meat strains matched those of one of two of the seven reference strains used. Seven meat strains whose RFLP restriction patterns of 16S rDNA genes differed from those of any reference strains probably represent four previously undescribed species. Although RFLP analysis of the amplified 16S rDNA gene allowed differentiation of psychrophilic and psychrotrophic clostridia at the genotypic species level and below, comparison of PCR-RFLP patterns and 16S rDNA sequences of unknown clostridial isolates with patterns and sequences of reference strains may not effect ready identification of these micro-organisms. The results of this study will be useful in diagnosis of the cause of premature spoilage of chilled vacuum-packed meats and in tracing spoilage-causing clostridia to their source(s) in the abattoir.

This study was undertaken to determine if carbon dioxide packaging of meat afforded a food safety advantage over vacuum packaging with respect to botulinal toxin production during chilled storage. A cocktail of washed spores from five toxigenic clostridial strains - four reference Clostridium botulinum strains [types A, B (2 strains) and E] and a C. butyricum type E strain - was inoculated onto lamb chumps. Of these strains, two were psychrotolerant. The inoculated chumps were individually carbon dioxide packaged and duplicate packs were placed into storage at 10, 8, 6, 4 and 2C. All storage regimens included a weekly defrost cycle when meat surface temperatures increased by up to 6 to 7C during a 2 to 2.5 h period. After 84 days storage, packs were assessed for the presence of botulinal toxin using the mouse bioassay procedure. All packs contained botulinal toxin. To compare toxin production in vacuum and carbon dioxide packs at chill temperatures, the challenge trials were repeated for 4 and 2C storage. Packs were examined at regular intervals for toxin presence. Both pack types contained toxin after 21 and 48 days storage at 4 and 2C, respectively. In the unlikely, but not impossible, event that raw meat would be contaminated with psychrotolerant toxin-capable clostridial spores, product safety, with respect to botulinal toxin presence after prolonged chilled storage, requires storage temperatures to be maintained below 2C for both vacuum and carbon dioxide packaged product.

B cell response to Trichinella spiralis (Ts) adult antigen (Ag) was studied in rats 1–20 days postinfection. B cell recoveries from the mesenteric lymph node (MLN), Peyer's patches (PP), thoracic duct lymph (TDL), and the spleen were determined by FACS analysis and Ag-specific antibody-producing cells (Ab-pc) in these tissues were enumerated using the immunoplaque assay. Total B cell numbers increased 2–70 times from day 3 postinfection in the MLN and TDL obtained from MLN-resected rats (MX) and such proliferation was not found in the PP or the spleen. Ab-pc of all isotypes increased from day 3 in the MLN and from day 2 in the MX-TDL. Among all isotypes, IgE- and IgG1-pc showed the strongest response. Immunofluorescence study revealed that these B cells were activated in the non-PP region of the small intestine. These results indicate an early isotype switch to IgG1 and IgE production in Ts-infected small intestine.

The present study was undertaken to determine whether psychrotrophic Clostridium spp. could induce a bone-taint condition when inoculated into the joints of hot bovine hind legs that were then subjected to marginally abusive cooling conditions. The stifle and hip joints of the hind legs of freshly slaughtered cattle were inoculated with single-strain cultures of 14 psychrotrophic Clostridium spp. isolated from spoiled chilled meat or with cultures of a mesophilic or a psychrotrophic reference strain. Inoculated legs were chilled in a cooling tunnel programmed to simulate marginally abusive cooling (deep tissue temperature reduced from 38 to 20°C in 20 h). After cooling, deep-seated, strongly offensive odours were evident in some of the inoculated joints and tissue surrounding those joints. It can, therefore, be postulated that at least some strains of psychrotrophic Clostridium spp. have the potential to be primary causative agents of bone-taint.

Isolates (259) of psychrotrophic Clostridium spp. associated with either blown pack spoilage (five isolates) or slaughter stock (254 isolates) were screened for the presence of botulinum neurotoxin (BoNT) genes using degenerate PCR primers capable of amplifying A, B, E, F and G BoNT genes. No BoNT gene amplification products were detected using DNA templates from the 259 psychrotrophic isolates, including 249 isolates that showed the same 16S rRNA gene Restriction Fragment Length Polymorphism (RFLP) patterns as authentic Cl. botulinum type B. It is concluded that although the growth of such micro-organisms in vacuum-packed chilled meat leads to product spoilage, it does not prejudice product safety.

Striploins derived from hot and cold boned sides were halved, with one half being vacuum packed and the other carbon dioxide packed. Packaged striploins were stored at −1°C. After 4, 8, 12 and 16 weeks storage, three packs of product from each of the four boning/packaging treatments were removed and subjected to tenderness and retail performance evaluation. For all storage periods, steaks derived from hot and cold boned striploins performed similarly in respect to pH, tenderness, microbiological quality and colour stability during retail display at 5°C. Effective retail display life was determined by appearance deterioration rather than microbial spoilage. For all steaks derived from striploins that had been in chilled storage for more than 4 weeks, the effective retail display life was approximately 24 h. It is, therefore, concluded that both hot and cold processing are capable of producing primal cuts of comparable tenderness and retail display performance. ©

This study determined the hygienic adequacy of a commercial cold and a commercial hot beef processing system. Two product lines were evaluated for each system: chilled vacuum-packed striploins and frozen brisket end trim. These two products represent respectively a primal cut that receives minimal handling and trimming and a product that is subjected to considerable handling and trimming. The hygienic adequacy of the two processes was determined from product data collected at appropriate times during processing. These data include temperature profiles, which were used for Process Hygiene Index (a temperature function integration indicating mesophilic growth potential) determination, and microbiological examination. As approved commercial operations, the processes evaluated were assumed to be compliant with the appropriate regulatory requirements. Results indicated that at comparable processing stages, the cold and hot processing systems were microbiologically equivalent.

Low-frequency, seasonal variations in sea level and sea-surface temperature (SST) for the north-east coast of the North Island, New Zealand were investigated using mainly multivariate analyses in the frequency domain over a 20-year period (1973–92). The dominant influence on the annual cycle of sea level (mean amplitude=378 mm) is associated with thermo-steric sea-level adjustments, which explains 50–80% of the variance in the annual frequency band. Sea levels generally peak at the end of April (austral autumn), lagging the SST cycle by around 2 months. The inclusion of secondary forcing variables (barometric pressure and alongshore wind stress) in the multivariate analysis increases the proportion of the variance explained to 70–90+%. Thermo-steric adjustments in sea level almost completely mask the inverted-barometer effect at annual and longer timescales. The response of sea level to wind stress (alongshore) is also anticorrelated to its response to barometric pressure, thereby appearing to reduce the magnitude of the barometric factor below 10 mm hPa−1. These latter factors, along with changes in oceanic current patterns and seasonal coupling of El Nino–Southern Oscillation effects, cause secondary effects on seasonal sea-level variability.

Aerobic and anaerobic plate counts were compared for routine monitoring of the microflora, dominated by lactic acid bacteria, developing on vacuum- and carbon dioxide-packaged raw meat during chilled storage. No statistical differences were observed between aerobic and anaerobic enumerations, made on plate count and blood agar plates, of the microflora developing on beef striploins packaged under vacuum or carbon dioxide during 14 weeks' storage at 0 degree C. With both techniques the spoilage microflora development differed between the two packaging regimes. The results indicate that there is no necessity for aerobic plate counts to be replaced by anaerobic plate counts in the routine microbiological examination of the spoilage microflora developing on chilled meats packaged under anoxic modified atmospheres.

Three beef dressing lines of different capacity (160, 440 and 800 head d(-1)) were investigated with respect to contamination associated with carcass/hide and carcass/faeces contacts, the distribution of microbial contamination on carcasses and the antimicrobial efficacy of cold water carcass washes. Swab samples were taken from up to 17 sites for determination of Aerobic Plate Counts at 37 degrees C (APC 37 degrees C) and Escherichia coli enumeration using the Petrifilm procedure. The three beef dressing systems produced virtually identical patterns of microbial contamination. High contamination was found at those sites associated with opening cuts and/or subject to hide contact during hide removal. Where contamination is intermittent, the use of mean microbial data tended to obscure evidence of faecal or hide contact. Consequently, worst-case results, as represented by the 95th percentile value, were used to identify probable instances and sources of contact contamination. Sites not subject to faecal contamination or hide contact typically had swab sample APC (37 degrees C) values of less than log 2.00 cfu cm(-2) accompanied by the occasional detection of E. coli at levels below log 1.00 cfu cm(-2). Sites contacted by 'clean' hide typically had APC (37 degrees C) counts of log 3.00 cfu cm(-2) or greater accompanied by occasional E. coli counts not exceeding log 2.00 cfu cm(-2). Sites contaminated by direct faecal contact or contact with faecally contaminated hides typically had APC (37 degrees C) counts equal to, or greater than, log 4.00 cfu cm(-2) accompanied by E. coli counts exceeding log 2.00 cfu cm(-2). Cold water carcass washing was ineffective in removing microbial contamination and tended to bring about a posterior to anterior redistribution, resulting in increased counts at forequarter sites.

We illustrate the current status of the application of computer modelling methods to catalytic systems by taking recent examples from modelling of both long range and local structural properties of microporous materials, surface structures of oxides, sorption in zeolites, host-template interactions in aluminophosphates and reaction mechanisms on oxide surfaces and at acid sites in zeolites. We emphasise the role of modelling techniques in the interpretation of experimental studies in catalysis.

Two cooling regimes that complied with the New Zealand meat hygiene requirement that hot deboned meat be chilled to +7 °C or less within 24 hr of leaving the slaughter floor were evaluated for the production of chilled table meats. Electrically stimulated hot deboned bull beef half striploins were either vacuum or carbon dioxide packed before being cooled in accordance with either Regime 1 (cool at +5 °C for 24 hr, transfer to chiller operating at -1.0 ± 0.5 °C) or Regime 2 (cool at +5 °C for 24 hr, hold at 5 °C for 6 days, transfer to chiller operating at -1.0 ± 0.5 °C). Striploins were removed from -1.0 °C storage 8, 28, 42, 56, 70, 84 and 98 days after slaughter and subjected to microbiological, tenderness, sensory and retail display performance evaluations. Both Regimes 1 and 2 produced meat of acceptable mean tenderness, 8 kgF (MIRINZ Tenderometer) in either vacuum or carbon dioxide packs within 28 and 8 days of slaughter, respectively. However, 70 days after slaughter the first signs of over-ageing became apparent. Steaks from Regimes 1 and 2 maintained acceptable visual appearance during retail display at 5 °C for 48 hr and 24 hr, respectively. After these times, the product was judged by the panel to be unacceptable because of its dull dark lean tissue and grey to green discoloration of the fat. Poor colour stability during retail display was mirrored by deterioration of sensory attributes, particularly aroma which is indicative of incipient spoilage. While carbon dioxide packaging in combination with Regime 1 offered an initial microbiological advantage over vacuum packaging, this advantage was not, however, carried over into retail display. Poor colour and sensory stability during retail display suggest that chilled table cuts derived from hot deboned bull beef are more suited to the Hotel-Restaurant-Institutional (HRI) trade than supermarket retailing. To serve the HRI, vacuum packed hot deboned bull beef primal cuts processed by Regime 1 appear to be the combination of choice. This combination would enable commercial processors to produce quality table beef with a chilled storage life of up to 70 days.

Chilled striploins and cube rolls from ten Australian steers (grain-fed for 150 days) were trimmed of external fat and cut transversely into portions approximately 10 cm thick, each weighing between 750 and 1000 g. These ‘retailer-ready’ cuts were each wrapped in drip saver pads and slid inside a plastic sleeve before being individually placed into a clear plastic high oxygen barrier film, metallized film or conventional vacuum bag. Cuts in clear plastic and metallized film packs were packaged in an oxygen-free saturated carbon dioxide atmosphere ( CO 2 -CAP), those in vacuum bags were conventionally vacuum-packed. All packs were returned to the chiller for further cooling. After 24 hr, half the clear plastic and metallized CO 2 -CAP packs were carbon dioxide master-packed in groups of eight. Retailer-ready cuts in both clear plastic and metallized film single unit and master-packed CO 2 -CAP packs were air freighted to New Zealand and sea freighted to Japan for assessment. The control vacuum packs were all consigned to New Zealand. Assessments in both countries after 39–89 days storage at between 0 °C and −1.0 °C indicated that fat colour stability limited the retail display life of steaks cut from meat in these retailer-ready packs to approximately 48 hr. In this regard, meat from single unit CO 2 -CAP, master pack CO 2 -CAP and vacuum packs performed similarly. Lean meat colour and sensory attributes remained acceptable for up to 48 hr after displayed product was rejected because of grey-green fat discoloration. The microbiological status of retailer-ready cuts removed from CO 2 -CAP packs after 89 days chilled storage was superior to that of cuts from vacuum packs. Clear plastic and metallized film CO 2 -CAP packs performed comparably.

Immunoglobulin (Ig) E is the principal Ig involved in immediate hypersensitivities and chronic allergic diseases such as asthma. Helminths are the most potent infectious agents known for their capacity to stimulate IgE production during the course of infection. In rats, the nematode Trichinella spiralis typically elicits a strong parasite-specific IgE response during infection, and this IgE antibody has been shown to be protective against the parasite in passive transfer experiments. The study reported here analyzed the fate of 125I-labeled myeloma IgE (1R162) in normal and T. spiralis-infected rats after intravenous injection. T. spiralis infection induced a capacity for specific binding to the gut wall of 125I-IgE rather than 125I-IgG1, as well as the transport of IgE, but not IgG1, into the gut lumen. Peak intestinal uptake and transport of 125I-IgE occurred during the first and second weeks after injection but was not elevated in the fourth week, that is, after intestinal adult worms had been expelled. Neither 125I-IgE uptake in the gut wall nor transport to the lumen could be ascribed to tissue damage or vascular leakage. Luminal transport occurred in the small intestine and not the liver, which only transports low molecular weight degraded 125I-IgE. Calculations based on the amount of intact IgE in the lumen suggest that, in a 24-h period, up to 20% of injected 125I-IgE can be transported to the gut lumen during the peak transport period, between 6 and 14 d after infection. The intestinal IgE binding and transport response can be adoptively transferred with T. spiralis immune CD4+ OX22- (CD45RC-) lymphocytes, which are protective, but not the nonprotective sister population CD4+ OX22+ (CD45RC+) of lymphocytes isolated simultaneously from thoracic duct lymph of infected rats. The intravenous infusion of recombinant rat interleukin 4 also elicited significant intestinal uptake of 125I-IgE. We also present evidence for the presence of CD23 on rat intraepithelial lymphocytes. These data provide evidence for a novel, inducible, intestine-specific IgE uptake and transport mechanism.

The development of meat hygiene is traced from its historical beginnings in ancient religious tradition to the veterinary-science-based organoleptic inspection systems of today. These systems, developed in Europe at the turn of the century when zoonotic disease was prevalent in slaughter stock, have been transposed across animal age and species, as well as geographical boundaries, resulting in the present similarity of meat inspection systems worldwide. The interaction of scientific capability, consumer demands and economic constraints is considered with respect to developing scientifically based, manpower-efficient, cost-effective meat hygiene and inspection systems that will be needed to ensure public health protection into the twenty-first century.

Nine hybridoma cell lines secreting monoclonal antibodies (mAbs) against Trichinella spiralis muscle larvae (ML) excretory/secretory antigens (ESA) were developed. Two mAbs, 6-D8-E3 (6D8) and 6-B1-G10 (6B1), were studied in detail. Western blot analysis using ML ESA showed that 6D8 recognized 35- and 40-kDa constituents whereas 6B1 identified a doublet of 33 kDa. However, Western blots of SDS-PAGE of crude ML homogenate showed that 6D8 identified proteins of approximately 35 and 43-60 kDa, whereas 6B1 recognized bands of 42-50 kDa. These results indicated substantial apparent MW differences between secreted and nonsecreted proteins recognized by both mAbs. Neither 6D8 nor 6B1 reacted with adult worm ESA, but both recognized antigens in aqueous extracts of homogenates of whole adult worms. Competitive inhibition experiments using ML ESA as a target demonstrated that the antigen epitopes recognized by monoclonals 6D8, 6B1, a rat mAb, 9D4, and a 37-kDa antigen previously defined were noncross-reactive. MAbs 6D8, 6B1, and 9D4 were used to isolate proteins possessing target determinants by affinity chromatography from crude ML homogenates. Each mAb isolated distinct protein species as determined by SDS-PAGE (6B1, approximately 42 kDa; 6D8, approximately 28, 37, and 61 kDa; 9D4, approximately 29, 33, 38-57, 80, and 86 kDa). NFS mice responded in a dose-dependent manner to affinity-purified antigens and were 25-fold more effective (by weight of antigen) than either C3Heb/Fe(C3H) or B10.BR mice. Immunization of mice with 6D8, 6B1, or 9D4 antigens induced strong protection against a subsequent challenge infection in NFS mice as indicated by accelerated intestinal adult worm expulsion, reduced fecundity of the female worms, and reduction of ML burden. Affinity-isolated antigens stimulated in vitro proliferation of spleen and MLN cells from immune mice; however, the mitogenic response to these antigens barely varied among NFS, C3H, and B10.BR strains.

The 16S–23S rDNA internal transcribed spacer (ITS) polymorphism analysis was assessed for its suitability in rapid discrimination between species of psychrophilic and psychrotolerant clostridia associated with ‘blown pack’ spoilage of vacuum-packed meats. DNA isolated from 10 reference and 20 meat strains of psychrophilic and psychrotolerant clostridia were used as templates in PCR amplification with primers complementary to conserved regions of the 3′ end of the 16S rRNA and 5′ end of the 23S rRNA genes directly flanking the spacer. The majority of strains showed multi-band ITS patterns when products of spacer amplification were visualised on an agarose gel. With the majority of meat strains, PCR amplification generated single banding pattern for a single clostridial species. However, meat strains of Cl. algidicarnis produced four different ITS banding patterns. With reference strains of psychrophilic and psychrotolerant clostridia, variation in spacer length was also observed between nonproteolytic Cl. botulinum type B (17B), E (Beluga) and F (202F). On the other hand, the number and size of the ITS amplification products could not be used for a differentiation of Cl. laramiense ATCC 51254T from Cl. estertheticum DSM 8809T, Cl. putrefaciens DSM 1291T from Cl. algidicarnis NCFB 2931T, or Cl. frigidicarnis strains from nonproteolytic Cl. botulinum type B (17B). The presence of interstrain, and lack of interspecies, ITS polymorphism observed in the present study with some clostridial species may preclude the use of 16S–23S rDNA spacer amplification for species-level discrimination and identification, respectively, of psychrophilic and psychrotolerant clostridia associated with meat spoilage. However, where interstrain, intraspecies heterogeneity of ITS amplification products exists, ITS analysis could be useful for tracing back psychrophilic and psychrotolerant clostridia responsible for meat spoilage to their meat plant sources.

Two psychrophilic Clostridium strains, DB1AT and R26, were isolated from incidences of 'blown-pack' spoilage of vacuum-packed chilled lamb. Vacuum packs of meat inoculated with these strains developed gas bubbles and pack distension within 14 d storage at 2 degrees C. The two main gases responsible for pack distension were carbon dioxide and hydrogen. 1-Butanol, butyric and acetic acid and butyl esters were the major volatile compounds produced by the strains in the artificially inoculated packs. The unknown strains were Gram-positive motile rods producing elliptical subterminal spores during the late-stationary growth phase. At pH 7.0, they grew from -1.5 to 26 degrees C, and their optimum growth temperature was 20-22 degrees C. At 20 degrees C, the pH range for growth was 5.4-8.9 and the optimum pH for growth was 6.2-8.6. In peptone/yeast extract broth, the organisms grew little or not at all in the absence of fermentable carbohydrates. Both strains hydrolysed gelatin, aesculin and starch. The fermentation products formed in peptone yeast extract glucose starch broth were ethanol, acetate, butyrate, lactate, butanol, carbon dioxide and hydrogen. The G+C contents of the DNA of strains DB1AT and R26 were 29.4 and 28.3 mol%, respectively. Phylogenetic analyses indicated that the strains belong to cluster I of the genus Clostridium (sensu Collins et al. 1994). The new strains differed from the phylogenetically related clostridia in cellular fatty acid composition, soluble protein profiles and phenotypic properties. On the basis of rDNA analysis and phenotypic and phylogenetic characterization, the strains were assigned to a new species for which the name Clostridium gasigenes is proposed. Strain DB1AT (= DSM 12272T) is designated as the type strain.

A psychrotolerant Clostridium species was isolated from vacuum-packed, temperature-abused raw lamb. Colonies of this micro-organism on sheep-blood agar were circular with an entire margin, grey-white, translucent and beta-haemolytic. Cells were single, tapered, motile rods. Elliptical subterminal spores were produced in the late stationary growth phase. Spores did not cause swelling of the maternal cells. The micro-organism was obligately anaerobic. In peptone yeast extract glucose starch (PYGS) broth at pH 7.0, the micro-organism grew optimally between 25.5 and 30.0 degrees C. The temperature range for growth was 2.5-32.2 degrees C. At 26 degrees C, the micro-organism grew optimally at pH 6.8 to 7.0. The pH range for anaerobic growth was 4.7-9.1. The micro-organism was saccharoclastic, hydrolysed starch and degraded xylan. The fermentation products formed in PYGS broth were acetate, formate, lactate, ethanol, butyrate, butanol, hydrogen and carbon dioxide. The G + C content of the DNA was 38.4 mol%. Phylogenetic analyses indicated that the strain belongs to cluster XIVa of the genus Clostridium (sensu Collins et al. 1994). The new strain differed from phylogenetically related clostridia in terms of cellular fatty acid composition, soluble protein profiles and phenotypic properties. On the basis of phenotypic and genotypic characterization data, the strain was assigned to a new species, namely Clostridium algidixylanolyticum. The type strain is strain SPL73T (= DSM 12273T).

/ spraying, their use has to be carefully controlled and backed by drug treatment. Some 2.6 million nets have been treated so far but it is too early to judge whether or not they could contribute to the control of malaria on a large scale. Chemoprophylaxis Certain groups, such as children, preg- nant women and migrants, are particu- larly at risk from malaria, and trials in The Gambia, reported by Brian Greenwood (Medical Research Council Laboratories, Fajara, The Gambia) suggest that targeted prophylaxis, particularly with maloprim, can make a significant impact on malaria and its side effects in these groups. The problems associated with this approach are that it is relatively expensive and difficult to sustain, it might enhance the possibilities of resistance and it might interfere with the acquisition of immunity. In the future, preventative chemoprophy- laxis might be well worth considering in areas where the infrastructure could ensure effective treatment and there is no drug resistance. Even if not used prophylactically, anti- malarial drugs must be regarded as the mainstay of malaria control in the im- mediate future and will remain so if and when a vaccine becomes available. There is no way of hiding the fact that reliance on the use of drugs is likely to encounter major problems, particularly the emerg- ence of resistance and the difficulties inherent in their distribution. Anders Bjorkman (Karolinska Institute, Stock- holm, Sweden) outlined the changing pat- terns of drug resistance which now ex- tends to chloroquine, pyrimethamine, mefloquine and quinine and is likely to occur with halofantrine and artemisinine. Practical aspects of drug resistance were discussed by Nick White (Mahidol Uni- versity, Bangkok, Thailand), who pin- pointed a number of major gaps in our knowledge. For example, does chloro- quine resistance decline in the absence of the drug? Is there any evidence for signifi- cant resistance to quinine? How can new drugs be protected against resistance? Even if a cheap and effective drug does become available, the problem of getting the drugto the right people will still remain a problem, a subject that was discussed by Susan Foster (London School of Hygiene and Tropical Medicine, UK), who reviewed evidence that the majority of antimalarial drugs travelled through un- official channels to reach those infected, something that will always distort the interpretation of any control campaign. The Way Ahead There is no doubt that a massive gulf exists between the optimists, who are largely laboratory based, and the pessi- mists, many of whom are concerned with the 'real world', and this meeting will be judged to have been a great success if all it did was to bring people with different ideas together. The overwhelming im- pression from the meeting was that there is a lot of malaria around and that there will be for many years to come, and the immediate problem is how to live with it now and how to bring it within the bounds of a possible eradication pro- gramme. A solution could be an amalgam of lots of little local ones. A few fish, a covered ditch and an impregnated bed- net may not seem very sophisticated but they do prevent malaria and, what is more, can be seen to do so. Waiting for the vaccine should not be allowed to become an excuse for inaction. F.E.G. Cox

Two strains of a psychrotolerant Clostridium, isolated from vacuum-packed, temperature-abused beef, were characterized using a multiphasic approach. The strains were Gram-positive motile rods producing elliptical subterminal spores during early stationary growth phase. The strains were psychrotolerant. At pH 7.0, they grew between 3.8 and 40.5 degrees C; their optimum growth temperature was 30.0-38.5 degrees C. At 30 degrees C, the pH range for growth was between 4.7 and 9.5; the optimum pH for growth was 6.4-7.2. The organisms were proteolytic and saccharolytic, lecithinase-positive and hydrolysed gelatin. The fermentation products formed in peptone/yeast extract/glucose/starch broth were acetate, ethanol, butyrate, isovalerate, butanol, isobutyrate, oxalacetate, lactate, hydrogen and carbon dioxide. The DNA G + C compositions of the two meat strains were 27.3 and 28.4 mol%. Phylogenetic analyses indicated that the strains belong to Cluster I of the genus Clostridium (sensu Collins et al., 1994). The new strains differed from phylogenetically related clostridia in terms of cellular fatty acid composition, soluble protein profiles and phenotypic properties. On the basis of phenotypic and genotypic characterization data, the strains were assigned to a new species for which the name Clostridium frigidicarnis is proposed; strain SPL77AT (= DSM 12271T) is the type strain.

Conoco (U.K.) Limited (CUKL) has a proud history of achievement in its approach to Health and Safety management. Our motto, Our work is never so urgent or important that we cannot take time to do it safely, fosters a principled approach to safety management and has served us well for many years. The continuing challenge is to ensure that the organisation does not become complacent in respect of safety management. Whilst strong leadership and management commitment are critical in the achievement of a safe performance, they represent only one measure of success. Conoco believes that the key to excellence in this area is the enrolment of the entire workforce; the employees and contractor personnel alike who are engaged in the work of the company thus creating a balanced approach to Health and Safety management. This paper will describe clearly the action taken, primarily since the beginning of 1997, in achieving the balanced approach while considering the consequent effect on safety performance.

Bell, R. G., Adams, L., Coleman, S., Negrao-Correa, D., and Klei, T. 1999. Brugia pahangi: Quantitative analysis of infection in several inbred rat strains. Experimental Parasitology92, 120–130. We report a comprehensive study of the infectivity of Brugia pahangi in male and female rats of eight different inbred strains. A single infection of any inbred rat strain will produce rats that become microfilaremic, have occult infection, or clear the primary infection. The proportion belonging to any category is determined by the basic susceptibility level of that strain. Patency rates (blood microfilaria+) ranged from 24% (AO rats) to 73% (WKA rats). The period for which microfilaria were in the circulation was directly related to microfilarial burden, with rats carrying less than 50 mf/ml of blood patent for 11.8 weeks ± 12.2; for 50–499 mf/ml it was 37.6 ± 14.8 and for 500+ mf/ml it was 63.3 ± 34.2 weeks. Suckling rats were resistant to infection (0 patent) and weanlings were intermediate in resistance between suckling and adult rats. Female rats were highly resistant to infection. Approximately half of amicrofilaremic rats have occult infections. A high proportion of patent infections involve the testes or testicular lymphatics. In the most susceptible rat strains, more than 95% of the administered L3 or developing L4 parasites were killed within 28 days. During the course of the first 6 months, the ratio of males to females fell significantly, suggesting a shorter life span in male worms. The features of the infectivity/patency patterns in rats are compared with recognized patterns obtaining in human populations. We conclude that rats provide a valuable and underutilized model for the experimental analysis of filarial infections.

Total intestinal IgE level increased in rats infected with Trichinella spiralis or Heligmosomoides polygyrus (peak levels of 2.6 microg and 3.7 microg, respectively), but not in rats infected with Nippostrongylus brasiliensis. Intestinal implantation of young adult N. brasiliensis did not stimulate an intestinal immunoglobulin (Ig)E response, suggesting that mucosal penetration may be required for local intestinal IgE responses in rats. During a T. spiralis infection, total IgE levels in the intestinal lumen were consistently higher in LEWIS and LOU rats (rat strains that eliminate T. spiralis worms earlier in the infection) than in PVG, AO and WKA/H strain rats. There was no correlation in either the total level of serum IgE and IgA, or of intestinal IgA with differences between strains in the rate of worm elimination from the gut. Furthermore, the intestinal IgE immunoprecipitated from LEWIS rats 12 days after infection reacted with T. spiralis adult worm metabolic antigens, while intestinal IgE from PVG rats only became reactive with adult worm metabolic antigens from 14 days after infection. These data emphasize the significance of the intestinal IgE response and its unique features by comparison with serum IgE and IgA or intestinal IgA.

Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil, rock, and ice penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact of 125-fps. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these more sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reaches the electronics contained in the various mechanical system. As part of the investigation of packaging techniques, a two part study of shock mitigating materials is being conducted. This paper reports the first part of the shock mitigating materials study. A study to compare three thicknesses (0.125, 0.250, and 0.500 in.) of seventeen, unconfined materials for their shock mitigating characteristics has been completed with a split Hopkinson bar configuration. The nominal input as measured by strain gages on the incident Hopkinson bar is 50 fps {at} 100 {micro}s for these tests. It is hypothesized that a shock mitigating material has four purposes: to lengthen the shock pulse, to attenuate the shock pulse, to mitigate high frequency content in the shock pulse, and to absorb energy. Both time domain and frequency domain analyses of the split Hopkinson bar data have been performed to compare the materials` achievement of these purposes.

We analysed the cytokine profile of a T cell subset (CD4+ CD45 RC-) that confers protection against Trichinella spiralis infection in rats. These CD4+ cells are generated in the gut and appear in the thoracic duct lymph within 72 h after infection. Cytokine mRNA levels for IL-2, IL-3, IL-4, IL-5, IL-10 and IFN-gamma and functional cytokine secretion for IL-4, IL-5, IFN-gamma, TNF-alpha and mast cell differentiation activity were tested in vitro following stimulation with T. spiralis antigens. Compared to a non-protective T cell population (CD4+ CD45 RC+ or CD8+), also isolated from the same thoracic lymph, no significant differences were observed in the levels of mRNA for IL-2, IL-3, IL-4, IL-5, IL-10 or IFN-gamma in the protective CD4+ CD45 RC- cells. However, analysis of the cytokine activities in culture supernatant of these T cell subsets following 24 h stimulation in vitro with T. spiralis antigens showed that significant IL-4 and IL-5 activity but little IFN-gamma or TNF-alpha was secreted by the protective CD4+ CD45- RC- cells. Whereas the non-protective CD4+ CD45 RC+ cells secreted significant levels of IL-4, IFN-gamma, mast cell differentiating activity and TNF-alpha but little IL-5 activity. Non-protective CD8+ cells were found to secrete IL-4 but not IL-5. Production of IL-4 was essentially equal for both protective and non-protective T cell subsets. These findings suggest that the presence or absence of IFN-gamma secretion, rather than IL-4 alone, determines whether a T cell subset has protective activity against T. spiralis infection in rats.

The Catalysis and Sorption Project was founded in 1991 to develop modeling tools for studying the structures and properties of heterogeneous catalysts and sorbents. The computational technologies being advanced range from tools for catalyst characterization, model development and visualization, through physical simulations methods, to the extension and use of quantum chemistry techniques. This overview highlights recent progress in the selected application areas of catalyst structure determinations, prediction of particle morphologies, study of hydrothermal crystallization phenomena, and analyses at an ab initio level of point defects in ionic solids.

A cDNA of the complete coding region of rat IL-10 was cloned and sequenced using RNA isolated from a cultured population of thoracic duct T-lymphocytes obtained from Trichinella spiralis infected animals. The OX8 − OX22 − T-helper cells were stimulated in vitro with Concanavalin A for 24 hours prior to harvest. Reverse transcription of cellular RNA was primed with oligo-dT followed by amplification of IL-10 specific cDNA by polymerase chain reaction with synthetic oligo nucleotide primers chosen from two highly conserved regions of mouse and human IL-10. The sequence of the coding region of the amplified, cloned rat IL-10 cDNA is 90% identical to the mouse and 82% identical to the human IL-10 cDNA coding regions.

Five transport and storage trials were conducted on commercial shipments of vacuum-packaged beef half striploins imported into Saudi Arabia by sea from Australia, New Zealand and the Republic of Ireland. The cold chains, from packaging to the end of chilled storage in Saudi Arabia, were monitored using miniature electronic data loggers placed in cartons of striploins. Development of spoilage microfloras was followed from packaging to trial end using a differential aerobic plate count technique. Changes in meat pH, total volatile nitrogen (TVN) and free fatty acid (FFA) content were determined over the storage period. Sensory evaluations to identify spoilage conditions and to determine consumer acceptability were also conducted over the course of storage in Saudi Arabia. Results indicated that aerobic plate counts, TVN and FFA were all unsuitable as indicators of the fitness, or acceptability of vacuum-packaged beef for human consumption. Under good but commercially realistic conditions (i.e. normal ultimate pH beef, initial microbial contamination at packaging of less than 10 3 /cm 2 , packaging, film oxygen transmission rate less than 40 ml/m 2 /24 h/atm at 23°C and 90% R.H., and mean product temperature during transport and storage of 0°C), vacuum-packaged beef transported by sea has an anticipated product life of at least 90 days measured from the date of slaughter. Under the conditions just stated, deterioration of meat texture resulting from excessive aging rather than the onset of overt microbial spoilage will limit the effective product life of vacuum-packaged beef.

The rapid expulsion of Trichinella spiralis by mice of a variety of inbred and F1 mouse strains was examined. Mice were reinfected once with T. spiralis during and immediately after the natural termination of a primary infection and worm rejection was measured ⩽24 hr after the challenge. The results showed that the challenge (super)infection was consistently rejected by all mouse strains before rejection of the adult worms from the primary infection commenced. Rejection of the challenge infection began at different times after the primary infection with NFS (2 days) 5 days). In all strains, rejection of the challenge infection preceded adult worm rejection from the primary infection by 5–8 days. At its peak, the loss of challenge worms related directly to the strength of the primary rejection process NFS ⩾ 98%, C3H 90–98%, and B10 mice 80–90%. Furthermore, loss of the capacity to reject the challenge followed ~7 days after the complete loss of the primary infection in each strain examined. Thus, the sooner worms from the primary infection were lost, the earlier the capacity to promptly reject the challenge infection disappeared. B10.BR mice still partially rejected a superinfection 35 days after the primary infection began, whereas NFS mice lost this capacity around 25 days. However, premature termination of the primary infection in B10.BR mice with methyridine at the same time that NFS mice naturally terminated their infection (15 days) abrogated the capacity of B10.BR mice to reject the superinfection at 24 days. Passive transfer of protective rat IgG monoclonal antibody to mice did not lead to rapid expulsion. Transfer of mouse immune serum to intestinally primed rats did result in rapid expulsion, suggesting that mouse antibody responses were adequate. The expression of superinfection rejection was susceptible to the administration in vivo of GKI.5, anti-mouse L3T4 antibody. The data indicate that the principal determinant of the strength, time of initiation, and longevity of rejection of a challenge infection was the response to the primary infection of that individual mouse strain. The genetic determinants of challenge infection rejection were seen to be identical to those that determined rejection of the primary infection. Since no evidence could be found to support the identity of this response with rapid expulsion, as defined in rats, a new term, “associative expulsion,” is proposed. It is suggested that associative expulsion represents a specific T-cell-dependent antilarval immune reaction that may be potentiated by the processes associated with adult worm rejection.

Samples of boneless pork, lamb, beef (high and normal pH) were packaged in ‘100%’ carbon dioxide atmospheres in foil laminate pouches. These pouches were fitted with a septum and a gas sampling port that allowed the introduction of air and removal of gas samples for analysis from the sealed packs. After sealing, measured volumes of air were introduced into test packs that had been gassed at a carbon dioxide volume to meat weight ratio of either 1 litre/kg or 2 litres/kg, to give initial atmospheres containing approximately 0·1, 0·2 and 1·0% oxygen. After 24 and 168 h storage at −1·5 ± 0·5°C, test packs were removed and compared with similarly treated control packs without added oxygen with respect to meat odour, taste and colour. No significant differences between the test and control packs in respect to odour or taste were evident with any meat type. The tendency to develop browning in response to the presence of residual oxygen within packs, increased in the order: pork, normal pH beef, normal pH lamb, high pH beef. Beef and lamb developed noticeable browning in packs containing more than 0·15% total oxygen while pork was able to tolerate 1% oxygen without obvious detrimental effects. For all meat types, the colour stability was greater in packs gassed to the higher gas volume to meat weight ratio.

Thoracic duct cells that act synergistically with immune serum or antibody to transfer rapid expulsion of a challenge infection with Trichinella spiralis muscle larvae were characterized as OX38+, OX8-, OX22- T helper cells. Protective capacity was confined to the dividing T helpers that appeared on days 3-5 in the thoracic duct of rats during a T. spiralis infection. To realize their intestinal priming potential in recipient rats. MHC-compatibility between donor and recipient rat was required. Fractionation of immune serum with 40% saturated ammonium sulphate left transferable protective activity in both the precipitate and supernatant fractions. Absorption of immune serum with muscle larvae antigen removed the capacity to transfer protection.

Rapid expulsion of Trichinella spiralis could be transferred to naive adult rats with thoracic duct lymphocytes and immune serum. Thoracic duct cells collected from Days 3–5 and immune serum collected on Day 28, respectively, after infection were effective. Both cells and serum were unable to transfer rapid expulsion when given alone, even in large volumes. Recipients of immune serum and cells eliminated a significantly higher number of larvae than control rats by 1 hr after challenge with muscle larvae. Rapid expulsion produced 30–80% larval worm rejection but could not be increased by the transfer of more cells or immune serum. Mucus trapping did not appear to play a role in the rejection process. After transfer of 2 × 10 8 cells and 4.0 ml immune serum, rapid expulsion persisted for less than 1 week. However, after adoptive transfer of cells alone, the gut remained functionally receptive to the passive transfer of immune serum for 7 weeks. Therefore, the changes effected by transfer of cells were long lived in contrast to the 1 week, or less, of functional persistence by transferred immune serum. The data indicate that two separate processes, one cell mediated and the other immune serum mediated, interact synergistically in the intestine and lead to the expression of rapid expulsion.

The immunosuppressive effects of in vivo (subcutaneous) exposure to 40 or 80 mg/kg 3-methylcholanthrene (MC) were examined in aryl hydrocarbon hydroxylase (AHH) responsive C57BL/6 (B6) and AHH non-responsive DBA/2 (D2) inbred strains of mice. Twenty-four hours after treatment with carcinogen or vehicle alone, animals were primed with crude L1 muscle larvae antigen from T. spiralis. Immune status was assessed in vitro after six days as antigen-specific lymphoproliferation. The proliferation of splenocytes from MC-treated D2 and B6 mice was significantly impaired compared to controls. To examine the cellular basis of the immunosuppression, primed splenocytes from control and MC-treated mice were separated into adherent and non-adherent fractions on Sephadex G-10 columns. When antigen-pulsed adherent cells from MC-treated B6 and D2 mice were recombined with control non-adherent cells from syngeneic and B6D2F1 mice, T-cell proliferation was significantly reduced. This suppression was not observed with the addition of increased numbers of adherent cells. Non-adherent cells from MC-treated mice showed a decreased capacity to respond to the presence of control antigen-pulsed adherent cells from appropriate mice. These results suggest that MC treatment has a similar suppressive effect on the immune responses of both B6 and D2 mice that involves the quality of accessory cell-T-cell interactions.

Responsiveness of mouse strains after phase-specific immunization with Trichinella spiralis is compared. Two strains ( NFR N, NFS/N ) showed strong overall responsiveness. The response type could be characterized in phase-specific terms as: strongly anti-adult, weakly to moderately anti-preadult, and strongly antifecundity. By comparison, congenic mice of the C57B1 10 Sn background (B10·A, B10·D2, B10·S, B10·Q) displayed poor total responses that could be characterized as: weakly anti-adult, very weakly anti-preadult, weakly anti-fecundity after preadult immunization, and mixed (weak and strong) after adult immunization. The C 3 H HeJ mouse appeared to be intermediate between the B10·BR and the NFR N strains in overall responsiveness. Genetic determinants of anti-preadult or anti-adult responses of NFR N strain mice were dominant over their B10 congenic counterparts as shown in F1, crosses of NFR N × B1O·BR mice. Since the NFR N (predominantly H-2q) and the NFS N (H-2S) are both strong responders, while the B10·Q(H-2q) and B10·S (H-2S) are weak, it is suggested that the major genes controlling anti-preadult and anti-adult responses are not linked to the major histocompatibility complex. However, variations in anti-adult immunity and anti-fecundity in the B10 congenic mice (B10·Q and B10·S are the strongest responders) suggest that minor genes linked to the MHC exert some control over these responses. Some evidence was obtained for gene complementation as the F1 cross of NFR N and NFS N mice responded more vigorously than the parental lines. We conclude that multiple genes determine anti-T. spiralis intestinal responses in mice. The major genes are unlinked to the major histocompatibility complex whereas several minor genes are linked.

Inbred mice infected with Trypanosoma musculi displayed wide variations in peak blood parasitemia. The most susceptible mice were C3H and A strain, while Balb/c, C57B1/6, and the related congenic B10 strains were the most resistant. The effect of an intestinal infection with either Trichinella spiralis or Heligmosomoides polygyrus on proliferation of T. musculi was investigated. T. spiralis infections given at the same time or up to 45 days before a T. musculi infection always caused an increase in blood parasitemia in C3H mice. Maximum increases were observed when T. spiralis infections preceded T. musculi by 5-10 days. In all mouse strains examined, dual infections increased maximum parasitemia by two- to four-fold, regardless of the degree of resistance of that mouse strain to either T. musculi or T. spiralis. This suggested that the immunological "cost" of a T. spiralis infection was the same for strains that were strong or weak responders to a primary infection with T. spiralis. In contrast, infection with H. polygyrus did not promote T. musculi parasitemia over the level of a single infection. The increase in blood parasitemia in T. spiralis-infected mice was largely due to the intestinal adult worm, but migratory larvae and mature muscle larvae also stimulated increased parasitemias. The increase in parasitemia was proportionate to the dose of T. spiralis, and the sex of the host did not affect the blood trypanosome level.

The genetics of T. spiralis rejection from the intestine was examined in inbred mice belonging to three phenotypic categories of expulsion: strong (NFS), intermediate (C3H), and weak (B10 · BR). Experiments used various worm doses to analyze the day of worm rejection, defined as the day at which 98% expulsion of the infectious dose occurred. The F 1 of NFS (strong) × B10 · BR (weak) was a strong responder and the F 1 of the cross C3H (intermediate) × B10 · BR (weak) was intermediate. Analysis of time of rejection among offspring of the (NFS/B10 · BR) × B10 · BR backcross showed three segregating phenotypic categories which occurred in a ratio of 1:2:1 strong:intermediate:weak. Segregation analysis of C3H/B10 · BR intercross (F 2 ) mice produced a ratio of 3:1, intermediate:weak. The back-cross C3H/B10 · BR to the C3H parent produced 100% intermediate offspring and the back-cross to the B10 · BR parent segregated in a 1:1 ratio of intermedate:weak. Taken together the results of both sets of crosses demonstrated that strong responsiveness was a consequence of the additive effects of two dominant genes; either gene by itself conferred intermediate responsiveness. The additive nature of these dominant genes suggested that two distinct processes each lead to the expression of worm expulsion that is phenotypically intermediate and kinetically identical.

Process pasteurization values for reference temperature 70 degrees C (P70) were calculated from the temperature profiles of 250 g luncheon meat chubs cooked under experimental conditions. A simple equation relating Process P70-value and the time and temperature of cooking was derived. With minimal cooking (P70 = 40) the surviving microflora (10(3)/g) wad dominated by species of Lactobacillus, Brochothrix and Micrococcus. These organisms were destroyed by more intensive cooking (P70 = 105), leaving a flora (10(2)/g) composed of Bacillus and Micrococcus species. The spoilage that developed after 14 d storage at 25 degrees C reflected the severity of the heat treatment received by each chub: with P70 between 40 and 90, a Streptococcus spoilage sequence occurred; with P70 between 105 and 120, a Bacillus/Streptococcus spoilage sequence occurred; with P70 of 135 and above, a Bacillus spoilage sequence occurred. Cooking to a P70 = 75 was adequate to reduce the surviving microflora to the 10(2)/g level associated with current good manufacturing practice.

Summary The antibody-dependent cell-mediated larvicidal response of AO rats against Trichinella spiralis newborn larvae was studied in vivo. Rats were immunized with 2000-3000 muscle larvae orally and then challenged 6-20 days later with 10 000-20 000 newborn larvae intraperitoneally. Newborn larvae recovery from the peritoneal cavity decreased significantly and was accompanied by cuticular cell adherence and killing of newborn larvae by day 9 of infection. Similar effects were observed when newborn larvae were incubated with blood obtained from immunized rats. The cell adherence and larvicidal responses reached their peak by day 16 of the primary infection. Passive transfer experiments demonstrated that newborn larvae infectivity was substantially impaired once cell adherence occurred. Culicular adherence took place in vitro only when immune serum was added to the incubation medium. Complete destruction of newborn larvae in vivo after passive transfer, as measured by muscle larvae burden was only evident after exposure to both immune serum and immune cells, not to either alone. Non-specific stimulation of the peritoneal cavity with a sterile intestinal infection failed to induce cuticular adherence or larval killing in these rats. We conclude that a stage-specific antibody-dependent cell-mediated larvicidal response is rapidly generated in vivo after the host is exposed to newborn larvae. It is a systemic response which impairs the infectivity of newborn larvae and can destroy them before they reach muscle tissue.