(1----5)-linked beta-D-galactofuranosides are immunodominant in extracellular polysaccharides of Penicillium and Aspergillus species.

Aspergillus and Penicillium species produce extracellular polysaccharides which are immunologically active. Methyl beta-D-galactofuranoside interferes with the reaction between the polysaccharide antigens and the antibodies raised in rabbits. Of the different interlinked dimers of beta-D-galactofuranosides (1----2; 1----3; 1----5; 1----6) the (1----5) interlinked beta-D-galactofuranoside gave the highest inhibition. An increasing inhibitory effect of di-, tri-, tetra-, penta-, hexa-, and heptamer of (1----5) interlinked beta-D-galactofuranosides was observed. It was noticed that the penta-, hexa- and heptamer of (1----5) interlinked beta-D-galactofuranosides were able to link antibodies raised against the extracellular polysaccharides produced by Penicillium species. The tetramer molecule was able to neutralize the binding of antibodies, which are naturally present in human sera, to the polysaccharides produced by Penicillium and Aspergillus species.

Effect of steady hypothermia and normothermia on multimodality evoked potentials in human poikilothermia.

OBJECTIVE: To assess the effects of steady-state spontaneous hypothermia on multimodality evoked potentials and on peripheral nerve conduction in human poikilothermia. DESIGN AND SETTING: Case series at a university hospital. PATIENTS: Four patients (four women, aged 28 to 37 years) with acquired poikilothermia. MAIN OUTCOME MEASURES: Short-latency somatosensory, brain-stem auditory, and visual evoked potentials as well as motor and sensory peripheral nerve conduction velocity during steady-state spontaneous hypothermia and normothermia. RESULTS: The marked latency prolongation of all evoked potentials and decreased peripheral nerve conduction velocity observed during steady-state spontaneous hypothermia (mean +/- SD core temperature, 33.5 +/- 0.3 degrees C) compared with normothermia (36.9 +/- 0.4 degrees C) agrees with previous findings during short-term induced hypothermia. CONCLUSIONS: The unequivocal effect of sustained mild spontaneous hypothermia on evoked potentials and peripheral nerve conduction velocity underlines the importance of meticulous attention to even small alterations in core temperature in interpreting neurophysiological investigations.

Interaction of staphylococcal protein A in enzyme-linked immunosorbent assays for detecting staphylococcal antigens.

ELISA procedures for detecting staphylococcal antigens may be subject to interference by reactions between staphylococcal protein A (SPA) and IgG molecules. It was found that rabbit IgG reacted with SPA, both in the native state and after conjugation with peroxidase. Sheep IgG, however, did not react with SPA if conjugated with peroxidase. Peroxidase conjugated SPA reacted with rabbit IgG but not with sheep IgG. These results demonstrate that the source of IgG used in an ELISA system is of major importance to correct quantitation of staphylococcal antigens.

Interference of lysozyme in the sandwich enzyme-linked immunosorbent assay (ELISA).

Lysozyme can cause unreliable results in sandwich ELISA procedures, since it strongly associates with proteins with low isoelectric points. As immunoglobulins have an isoelectric point of about 5, lysozyme may form a bridge between the IgG in the coat and the IgG of the enzyme-labeled antibodies. For reliable ELISA results, it is necessary either to remove lysozyme from samples or to mask it. Both Cu2+ ions and ovalbumin were very effective in masking lysozyme and thus avoiding its linkage to immunoglobulins. Ovalbumin was not always as effective as Cu2+ ions because in test samples other proteins with high isoelectric points may be present which may compete with lysozyme for association with ovalbumin.

A comparative study of randomly amplified polymorphic DNA analysis and conventional phage typing for epidemiological studies of Listeria monocytogenes isolates.

The analysis of RAPD profiles generated by PCR with a single 10-mer, HLWL74, was compared to bacteriophage susceptibility data for epidemiological typing of Listeria monocytogenes strains. A total of 104 L. monocytogenes strains was screened, all from serogroup 1 or serotype 4b. Of these, 53 had been isolated during 6 different listeriosis outbreaks. The remaining 51 strains were chosen randomly from our collection. A total of 38 RAPD types were observed, although each epidemic group of strains isolated during one of these outbreaks displayed a specific RAPD profile. For 98% of the strains isolated during outbreaks, the correlation between RAPD typing and phage typing was complete. Only one strain, typed as epidemic by phage typing, was clearly distinguishable from the others by RAPD analysis. Among the 51 strains not related to an outbreak, 12 were linked to epidemic groups by RAPD analysis. Two of these rearrangements were supported by phage typing. The remaining 10 strains could be excluded by phage typing from any of the epidemic groups studies. Considering all 104 isolates, the decision to relate a strain to a particular epidemic group or to exclude a strain from any epidemic group was the same for 92 isolates, using either phage typing or RAPD analysis. The RAPD analysis, which is quick, simple and suited for automation, is proposed as an attractive alternative for phage typing in epidemiological studies of listeriosis.

Changes in carotid flow velocity induced by direct percutaneous carotid angiography in man.

Quantitative percutaneous flow velocity measurements are possible in carotid arteries. The results of the direct percutaneous angiography were measured by means of a Doppler directional flow velocity device and registered on a polygraphy. The results indicate an increase in the flow velocity of the injected as well as the non-injected carotid system. This implies that there are no local constrictions of the carotid artery following intervention and, furthermore, it implies a systematic effect of the puncture and injection itself, or of the contrast medium, on the whole cerebral circulation. A diffuse vasodilatation, at least in the cerebral circulation, is postulated. The possible implications are discussed.

The discriminating role of EEG power spectra in dyslexic children.

The aim of this investigation is to compare EEG power-density spectra between dyslexic and normal children. The children have been selected on the basis of specific reading and writing tasks; those with severe organic diseases and mental disorders were excluded. Groups aged 8, 9 and 10 years have been compared. In the 8-year-old group the power in the alpha band is higher in normals, in the 9-year-old group there was a higher power of the mu rhythm in normals and in the 10-year-old group the power in the temporal theta band is lower in normals. A possible relation between these findings and psychomotor development is discussed.

EEG spectra in children aged 8, 9 and 10 years. Reference values.

In a group of normal children aged 8, 9 and 10 years power density spectra of a 100-second EEG period were made over four different brain regions. All children had to undergo medical and psychological examinations prior to this EEG and the criteria for normality were based on these examinations. Reference values of the power density distribution for children between 8 and 10.5 years are given.

The preselection value of the Doppler LP test for shunt-therapy in patients with normal pressure hydrocephalus.

The results of this study confirm the hypothesis that the simple innocuous Doppler LP test may be useful in obtaining information about CSFP-CBF (cerebrospinal fluid pressure-cerebral blood flow) relationships. The value of this test in predicting the clinical outcome of CSF shunting in patients with normal pressure hydrocephalus (NPH) was studied. Fourteen patients with NPH were examined; eight patients showed a positive and six patients a negative Doppler LP test. Seven of the eight patients with a positive test improved following the shunting procedure, but none of the six patients improved after operation. This study suggests that the Doppler LP test is a useful preoperative selection test in patients with NPH. In addition this study supports the hypothesis that CBF autoregulation may be impaired with NPH.

Naturally occurring virulence-attenuated isolates of Listeria monocytogenes capable of inducing long term protection against infection by virulent strains of homologous and heterologous serotypes.

Experimental infections of mice with strains of Listeria spp. isolated from contaminated food sources allowed discrimination of strains into those either exhibiting high, attenuated or low virulence. Compared to the highly virulent L. monocytogenes strain EGD, an attenuated strain such as L99 persisted for shorter times (5 versus 10 days) in the infected host. Using a tissue culture cell model of infection, we found that, although strain L99 was capable of accumulating actin like its virulent counterpart following invasion, it was unable to generate the polarized actin tails required for intracellular and cell-to-cell movement. Immunoblot analysis using specific antiserum to the ActA polypeptide, a molecule that is necessary for movement of the bacterium within the eucaryotic cell, indicated that a slightly truncated form of this polypeptide was produced in the L99 strain. Despite its reduced virulence, the attenuated strain L99 was just as effective in generating protection in immune mice as the highly virulent strains, albeit with a 1000-fold higher infective dose. Based on the results obtained from this study, we suggest that one of the mechanisms accounting for widespread resistance in humans to infection by Listeria may be due to asymptomatic infections by naturally occurring strains attenuated for virulence.

Akinetic mutism with bithalamic infarction. Neurophysiological correlates.

A 42-year-old man presented with akinetic mutism, caused by bilateral thalamic infarction, resulting in a temporary amnesic syndrome and, finally, selective downgaze palsy. Electroencephalographic recording in the initial phase showed generalized spike- and-wave discharges, similar to those found in animal studies after lesion or stimulation of specific thalamic nuclei. Analysis of magnetic resonance images (MRI) of the head showed that the centre of ischemic necrosis particularly involved the intralaminar thalamic nuclei and a small part of the rostral mesencephalon. The findings support the previously suggested involvement of cortico-thalamo-mesencephalic circuitry in the initiation of motor responses, and the association of the non-specific thalamic nuclei with the appearance of generalized epileptiform phenomena in cases of reduced vigilance.

Features of the Guillain-Barré syndrome in mice following intraperitoneal injection of patient serum.

Intraperitoneal injection of serum from a patient with the Guillain-Barré syndrome (GBS) produced GBS-like signs in mice: inadequate respiration and weakness in the legs. We studied the clinical, electrophysiological and pathological features of these mice. Three groups of three mice were injected with patient serum from days 6, 10 and 15 after onset of neurological symptoms. GBS-like signs in mice were observed only with serum from day 6 and improved within 48 h. When serum was frozen and thawed more than once no signs were seen. Electrophysiological measurements of the sciatic nerves of injected and control mice were done before and after serum injection. Five days after injection of patient serum of day 6, the mice showed a significant decrease in the ratio between CMAP amplitude from proximal and distal stimulation and increase in H-M interval from proximal stimulation. These electrophysiological changes returned to normal within 12 days. The sciatic nerve showed no morphological abnormalities. Our results indicate that the observed GBS-like signs in mice are caused by peripheral nerve dysfunction.

Beriberi cardiomyopathy.

In Indonesia beriberi is still endemic, but subclinical cases are not uncommon. Three patients suffering from beriberi presented with different clinical manifestations. One had the classical features of Shoshin beriberi and the other two had the non-alcoholic cardiac beriberi (chronic type). The cardiac symptoms of all three patients responded dramatically to thiamine tetrahydrofurfuryl disulfide; there was also some improvement of their polyneuropathy, consistent with the neurophysiologic findings and somatosensory evoked potentials (SSEPs). We conclude that SSEPs provide additional clinical information on beriberi polyneuropathy. The mortality of untreated cardiovascular beriberi is high. In view of the harmless nature of the treatment, a good case could be made for routine administration of thiamine to all patients in whom heart failure is present without clear evidence of the cause.

Subclinical beriberi polyneuropathy in the low income group: an investigation with special tools on possible patients with suspected complaints.

OBJECTIVE: To determine the prevalence rate of subclinical beriberi polyneuropathy (PNP) in the low income group and to present new methods for early detection. DESIGN: We conducted a prospective, randomized observational study on all patients from family members of non-PNP patients presenting to the outpatient neurologic clinic of the Dr Soetomo Hospital in 1989 in Surabaya, Indonesia. MATERIAL AND METHODS: The 53 group I patients belonged to the low income series, whereas the 56 group II patients were from the mid- and high-income groups. We analyzed their diets and determined their blood thiamine levels. Neurologic, internal, psychiatric as well as neurophysiologic examinations were performed on all patients. RESULTS: The prevalence rate of subclinical beriberi PNP of the apparently healthy subjects of the low income group was 66% compared with 12.5% among the mid and high income groups. The exposure odds ratio was 13.6 (95% Cl, 2.78 to 8.04) indicating that the low income group ran a greater risk of developing beriberi PNP than the mid and high income groups. CONCLUSION: Most of our low income group patients had an inadequate diet, especially concerning deficient thiamine intake. Analysis of the diets revealed, that they were usually rich in carbohydrate especially steamed milled rice, whereas intake of fat and thiamine was low, protein was just sufficient. The calorie intake was marginal. Carbohydrate rich and non fat calories in the diet with low thiamine intake may provoke beriberi.

Risk assessment of Listeria monocytogenes in fish products: some general principles, mechanism of infection and the use of performance standards to control human exposure.

Risk assessment is increasingly used as a scientific process to assess the potential for adverse health effects to occur and as a basis for management of unacceptable risks. For each risk assessment activity, the purpose of the assessment should be clearly stated. For Listeria monocytogenes, the purpose of risk assessment may be providing information on the relative contribution of listeriosis to infectious diseases. For control purposes, the emphasis may be put on factors contributing to the risk of occurrence in a food or to inform risk managers that they should be setting food safety objectives. For an adequate risk assessment of L. monocytogenes, sound scientific data are necessary. This especially applies both to exposure assessment and hazard characterisation. Surveillance data indicates that cold storage to prolongs product shelf-life has opened an ecological window for the growth of L. monocytogenes. Assessment of dose-response relationship is often regarded as a key element in risk characterisation. Due to the large variability of the current assessed dose-response data, their contribution to assessing risks is low. The use of epidemiological data on incidence rate, types of food involved in listeriosis, etc. may be good alternatives. The use of performance standards or criteria, such as inactivation by heat or by fermentation, combined with processes that prevent outgrowth of the organism should be reconsidered. Presently, performance standards can simply be assessed since mathematical tools for their calculations are becoming increasingly available.

Immunological methods for detection of foodborne pathogens and their toxins.

Improved methods to detect microorganisms and their toxins introduced during the last decade involve among others recombinant DNA techniques and various immuno-assays such as the enzyme-linked immunosorbent assay and the latex agglutination. Immuno-assays are based on a quantitative reaction of an antigen (bacterial metabolite, e.g., toxin) with its antibody. Therefore, they are suited for detection of microorganisms based on their production of specific antigens and for quantitative detection of bacterial toxins. Sensitivity and specificity of immuno-assays are mainly determined by the antiserum used. In this respect the use of well selected monoclonal antibodies can be of advantage. With the enzyme-linked immunosorbent assay and latex agglutination test quantities of 0.1-1 ng of antigen/ml can be detected. Of both techniques the latex agglutination method has several advantages; the method is simple, inexpensive and rapid. Since each immuno-assay is sensitive to non-specific reactions, recognition of false positive results is necessary. The most appropriate method for this is to add an inhibitor to the test sample which blocks specifically the paratope of the immunoglobulin. Another general disadvantage of immuno-assays is that only the antigenicity is determined and this may differ from the actual toxicity. Therefore, antibodies should be used that react with the toxic centre(s) of the molecule, which can be accomplished by using well selected monoclonal antibodies.

Effect of water activity on growth and enterotoxin D production of Staphylococcus aureus.

Four enterotoxin D-producing strains of Staphylococcus aureus, were cultured at 37 degrees C in brain heart infusion broth adjusted to various water activity (aw) levels by means of NaCl. For high cell inocula growth of all strains and enterotoxin D production were observed within 6 days at aw levels down to 0.86.

Quantitative risk analysis and the production of microbiologically safe food: an introduction.

There is increasing interest in the application of quantitative risk analysis (QRA) in the production of microbiologically safe food products. QRA can be defined as a stepwise analysis of health risks which may be associated with a particular type of food product, resulting in an estimation of the probability of occurrence of negative health effects following the consumption of that food and the nature of these risks. Starting with this definition, the following successive components can be recognised: (1) hazard identification, which is a qualitative indication of the potential microbial hazards that may be associated with the consumption of a particular food product; (2) exposure assessment, which is the quantitative estimation of the dose of potentially hazardous organisms to which the consumer is exposed at the time of consumption of the food; (3) dose response assessment, which is the process of obtaining quantitative information on the negative effects of different levels of exposure to potentially hazardous organisms on the health of the consumer; (4) risk characterization, which comprises the activities that are carried out to rank the disorders according to severity, perception, economic and social consequences etc., enabling a decision to be made about the acceptance of a particular risk; and (5) risk management, which is the complex of analyses and judgements to reduce the probability of occurrence of unacceptable risks.

Evaluation and interpretation of data obtained with immunoassays and DNA-DNA hybridization techniques.

During the last decade several new analytical techniques have been developed for testing food products and clinical samples. One technique uses sensitive immunoassays such as enzyme-linked immunosorbent assay (ELISA) and latex agglutination. The most important step in developing sensitive immunoassays is the evaluation of the assay for specificity, cross-reactivity and sensitivity. False-negative results can easily be detected by adding known quantities of antigen to the sample. The most appropriate way to detect false-positive results is the specific inhibition of the immunological reaction by addition to the test-sample of either synthetic epitopes or anti-idiotype antibodies. The progress in recombinant DNA techniques now offers opportunities for application as analytical tools in food and clinical microbiology. Methods are being developed to detect microorganisms by their nucleic acid sequence using the so-called hybridization procedure. With this technique, labelled DNA fragments (probes) are hybridized with a complementary base sequence present in the microorganism. Foodborne pathogens can be detected by using a probe with a complementary base sequence which codes for toxin production. DNA-DNA hybridization techniques may replace the traditional cultural techniques for assaying pathogenic micro-organisms. However, more experience with these techniques is needed before further evaluation can be given.

Quantitative microbiological risk assessment.

The production of safe food is being increasingly based on the use of risk analysis, and this process is now in use to establish national and international food safety objectives. It is also being used more frequently to guarantee that safety objectives are met and that such guarantees are achieved in a cost-effective manner. One part of the overall risk analysis procedure-risk assessment-is the scientific process in which the hazards and risk factors are identified, and the risk estimate or risk profile is determined. Risk assessment is an especially important tool for governments when food safety objectives have to be developed in the case of 'new' contaminants in known products or known contaminants causing trouble in 'new' products. Risk assessment is also an important approach for food companies (i) during product development, (ii) during (hygienic) process optimalization, and (iii) as an extension (validation) of the more qualitative HACCP-plan. This paper discusses these two different types of risk assessment, and uses probability distribution functions to assess the risks posed by Escherichia coli O157:H7 in each case. Such approaches are essential elements of risk management, as they draw on all available information to derive accurate and realistic estimations of the risk posed. The paper also discusses the potential of scenario-analysis in simulating the impact of different or modified risk factors during the consideration of new or improved control measures.