Amplified enzyme-linked-immunofilter assays enable detection of 50-10(5) bacterial cells within 1 hour

1. The hydrolysis of organophosphate pesticides (OP) and nerve gases by serum paraoxonase (PON1) is an important factor determining their toxicity to mammals including man. The PON1 gene contains 2 polymorphic sites at amino acid positions 55 (L-->M) and 192 (G-->A, classically defined as the A and B genotypes) which result in several alloenzymes of PON1 in human serum. 2. The 192 polymorphism has previously been shown to affect PON1 activity. We have investigated the effect of both polymorphisms on the hydrolysis of paraoxon by serum from 279 healthy human subjects. 3. The 55 polymorphism significantly influenced PON1 activity. MM homozygotes had over 50% less activity towards paraoxon compared to the LL and LM genotypes regardless of the 192 genotype (P < 0.001). 4. Multiple regression analysis indicated that the 192 polymorphism, 55 polymorphism and serum PON1 concentration were responsible for 46, 16 and 13% of the variation in PON1 activity, respectively (all P < 0.001). None of the other parameters investigated significantly affected PON1 activity. 5. Therefore both PON1 polymorphisms affect the hydrolysis of paraoxon. AA/MM and AB/MM individuals may be potentially more susceptible to OP intoxication. 6. Genotyping individuals for both PON1 polymorphisms may provide a method for identifying those individuals at most risk of OP poisoning. The effect of PON1 polymorphisms on activity may also explain why some Gulf War Veterans have developed Gulf War Syndrome and some have not.     

Synaptic tagging: implications for late maintenance of hippocampal long-term potentiation

A novel property of hippocampal LTP, 'variable persistence', has recently been described that is, we argue, relevant to the role of LTP in information storage. Specifically, new results indicate that a particular pattern of synaptic activation can give rise, either to a relatively short-lasting LTP, or to a longer-lasting LTP as a function of the history of activation of the neuron. This has led to the idea that the induction of LTP is associated with the setting of a'synaptic tag' at activated synapses, whose role is to sequester plasticity-related proteins that then serve to stabilize temporary synaptic changes and so extend their persistence. In this article, we outline the synaptic tag hypothesis, compare predictions it makes with those of other theories about the persistence of LTP, and speculate about the cellular identity of the tag. In addition, we outline the requirement for aminergic activation to induce late LTP and consider the functional implications of the synaptic tag hypothesis with respect to long-term memory.     

Case report: The "veiled right kidney sign"--an ultrasound finding in retroperitoneal perforation of the duodenum

We report a case of traumatic duodenal perforation where the diagnosis was first considered during abdominal ultrasound examination. A subsequent CT scan identified the site of perforation which was confirmed at laparotomy. This condition typically produces few clinical signs or symptoms initially but has a high mortality related to delayed diagnosis. The ultrasound findings that prompted early diagnosis are described.