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Biomedical subjects

J G Banks

Publications and source records attributed to J G Banks.

10 recordsLinked to original sources

Growth of Listeria monocytogenes at refrigeration temperatures.

The growth of three strains of Listeria monocytogenes at refrigeration temperatures (-0.5 to 9.3 degrees C) in chicken broth and/or UHT milk was determined using a rocking temperature gradient incubator. Minimum growth temperatures ranged from -0.1 to -0.4 degree C for the three strains. Lag times of 1-3 d and 3 to greater than 34 d were observed with incubation at 5 and 0 degrees C respectively. Corresponding generation times ranged from 13-24 h at 5 degrees C and 62-131 h at 0 degree C. The type of culture medium had an influence on both the rate and extent of growth. Incubation of cultures at 4 degrees C before inoculation caused a marked reduction in the lag time when compared with cultures which had been previously incubated at 30 degrees C.

Animals

The cytotoxic and photodynamic inactivation of micro-organisms by Rose Bengal.

Rose Bengal was cytotoxic to the following bacteria at the concentrations given in parentheses (highest concentrations of dye in mol/l at which growth occurred on nutrient medium): Brochothrix thermosphacta and Deinococcus radiodurans (1 X 10(-6) or less); Streptococcus, Micrococcus, Staphylococcus, Bacillus, Arthrobacter and Kurthia spp. (1 X 10(-5)-1 X 10(-4], and Pseudomonas spp. and Enterobacteriaceae (5 X 10(-3)-1 X 10(-2) or greater). These organisms were killed rapidly when suspended in illuminated (170 microE/m2/s) solutions of Rose Bengal (1 X 10(-4) mol/l) providing oxygen was present. Singlet oxygen was identified as the lethal agent, because the rate of killing was increased by dissolving the dye in deuterium oxide while the organism were protected against photoinactivation by L-histidine or crocetin. Yeasts from chilled foods were killed in illuminated solutions of Rose Bengal but a light intensity of 315 microE/m2/s was needed for a death rate comparable with that of bacteria. The yeasts present in a range of chilled meat and dairy products failed to form colonies on Rose Bengal (5 X 10(-5) mol/l) media exposed continuously to modest illumination (55-80 microE/m2/s).

Bacteria

Sulfite, an elective agent in the microbiological and chemical changes occurring in uncooked comminuted meat products.

The literature dealing with sulfite preservation of meat products is reviewed. Discussion is centered on three aspects: (i) the elective action of sulfite, whereby its presence in meat products encourages the development of an association of Gram-positive bacteria (Brochothrix thermosphacta and homofermentative lactobacilli) and yeasts. Unsulfited products tend to be dominated by Pseudomonas fragi at chill, and Enterobacteriaceae at ambient temperatures; (ii) the diminution of the preservative potential of a meat product, which is associated with the binding of sulfite by acetaldehyde-producing yeasts; and (iii) the sparing action that sulfite has on the carbohydrates contained in the meat or included as an ingredient.

Ammonia

Endotoxaemia in septic shock: clinical and post mortem correlations.

The Limulus amoebocyte lysate assay was used as one of a series of laboratory and clinical investigations on a group of 31 patients suffering from septic shock in order to assess the clinical significance of this assay for the detection of circulating endotoxin in clinical gram-negative sepsis. Four patients with cardiogenic shock served as controls. Endotoxin was detected in the bloodstream of all patients with septic shock during the 24 h following referral and was not detected in the control patients. Eventual clinical recovery was associated with the disappearance of endotoxin from the peripheral blood. Blood cultures were unhelpful as a prognostic indicator in these critically ill patients. A quantitative assay of endotoxin in blood may allow a more precise relationship with the clinical manifestations of major sepsis.

Adolescent

The incidence and level of contamination of British fresh sausages and ingredients with salmonellas.

A five-tube most probable number (MPN) method, with the pre-enrichment and enrichment stages, was used in a study of the incidence of salmonella contamination of British fresh sausages and the ingredients used in their manufacture. All samples were taken from a large factory in the course of routine production. There was an incidence of 65% contamination of pork (n = 20) and 55% (n = 20) in pork and beef sausages. The incidences of contamination of uncooked ingredients varied from 95% for mechanically recovered meat (n = 20) to 10% for another type of meat. Cooked and/or dried ingredients were rarely contaminated with these organisms, and when contamination occurred, coliforms were also important. The numbers of salmonellas isolated ranged from 7-40 for pork sausages, from 8-24 for beef and pork sausages and from 0.8-378 organisms/g for ingredients. The following salmonella serotypes were isolated (ranked in descending order or incidence): S. derby, S. dublin, S. newport, S. stanley. S. typhimurium, S. heidelberg, S. infantis and S. agona.

Animals

Liver function in septic shock.

Serum liver function tests were estimated in 57 patients admitted to an Intensive Therapy Unit (ITU) with a diagnosis of septic shock. Following an initial biochemical disturbance, persisting hyperbilirubinaemia was associated with a poor prognosis. Post-mortem liver histology in 22 patients showed varying degrees of non-specific reactive change, venous congestion, ischaemic necrosis, fatty change and intrahepatic cholestasis in 16 cases. In the remaining six cases there was moderately severe cholestasis with inspissated bile in the cholangioles. The possible aetiology of the observed cholestasis is discussed.

Cholestasis, Intrahepatic

Perforation of the oesophagus: experience in a general hospital.

The results of a retrospective study of 62 patients who sustained perforation of the oesophagus during the period 1956--78 are reviewed. Oesophageal instrumentation was implicated in 40 patients. A total of 69 per cent of perforations occurred in the lower third; 45 per cent of patients remained undiagnosed for at least 24 h and in 23 patients remained undiagnosed for at least 24 h in 23 per cent the diagnosis was made only at post-mortem examination. Operative and non-operative management resulted in mortality rates of 48 per cent and 62 per cent respectively. Delay in operative treatment for more than 6 h was associated with increased mortality. However, 5 of 8 patients in whom diagnosis was delayed for more than 48 h recovered. The reason for this is discussed. The indications for conservative treatment are few and well defined; surgery is the treatment of choice. Early diagnosis and treatment are required if the mortality from oesophageal perforation is to be reduced.

Adult

Evening urinary oxalate excretion in stone formers.

Urine collections from stone formers and controls were made between 6 p.m. and midnight and analysed for oxalate content. No difference in oxalate output was found between these groups. This makes it unlikely that hyperabsorption of oxalate from the intestine is a common cause of idiopathic calcium oxalate stones. The convenience of 6-h urine collections for detecting hypercalciuria is discussed.

Calcium Oxalate

Natural antimicrobial systems and their potential in food preservation of the future.

The extensive literature on natural antimicrobial systems in animals, plants, and microorganisms is surveyed and particular systems are discussed, viz., the peroxidase systems in saliva and milk, singlet oxygen in the phagosome, cecropins and attacins in insects, complement, lysozyme and, to a limited extent, phytoalexins. The review draws attention to the cardinal role of targets on the cell envelopes of alien cells, especially bacteria, and emphasizes a possible approach to preservation based on the selection of specific agents for particular targets. The available evidence suggests that the perturbation of the homeostasis of all the organisms in the mixed flora of a food is unlikely to be achieved by one antimicrobial substance in isolation. Future studies need to consider therefore a tandem approach with two or more agents chosen because of their complementary action. Alternatively, natural system(s) and an established preservative method, either chemical or physical, warrant investigation. The extensive literature on the mechanisms whereby specialist pathogens overcome the defenses of plants and animals emphasizes the inherent dangers of selection leading to the persistent contamination of food processing areas with organisms tolerant of a particular antimicrobial system.

Animals