Sudden infant death syndrome (SIDS): are common bacterial toxins responsible, and do they have a vaccine potential?

Despite extensive research, no unifying concept has satisfactorily explained the cause of the sudden infant death syndrome (SIDS). The details are briefly outlined of some of the evidence supporting the hypothesis that common bacterial toxins are important in the aetiology of SIDS. These bacterial toxins act as triggers to initiate a biochemical cascade resulting in death. Data from four research groups, each working independently, indicated that the bacteria Clostridium perfringens, Escherichia coli, Staphylococcus aureus, Streptococcus spp. and Enterococcus spp. were present in higher numbers in infants who had suffered SIDS than in control infants. Certainly more detailed studies need to be performed on the role of bacterial infections in infants. There are many implications arising from this work, particularly the use of vaccination as a means of reducing infections, and consequently the number of SIDS deaths.

Success and failure rates of cylinder implants in type IV bone

It is well documented that implant success rates are much lower in Type IV bone than in Types I, II, and III. However, all of these studies have reported on the use of screw type implants. The present study demonstrates the efficacy of cylinder implant use in Type IV bone. A total of 513 cylinders were placed in Type IV bone and were followed for 0 to 60+ months in function. The absolute success rate was 95.7%. Of the 22 fixture failures encountered, 8 were discovered at the time of second stage surgery, 3 during the first year following uncovering, and 11 occurred after 24 to 36 months in function. A possible rationale for the higher success rate of cylinders as compared to that reported for screw type implants in Type IV bone is presented. Further well-controlled studies directly comparing various implant designs in a range of bony sites are needed to better understand and to fully document the differences suggested by the present study.

Cloning of the cyclomaltodextrinase gene from Bacillus subtilis high-temperature growth transformant H-17

The cyclomaltodextrinase gene from Bacillus subtilis high-temperature growth transformant H-17 was cloned on separate PstI, BamHI, and EcoRI fragments into the plasmid vector pUC18, but was expressed in an inactive form in the host, Escherichia coli DH5 alpha. High level constitutive expression of the gene product was also detrimental to the E. coli host, which led to structural instability of the recombinant plasmid. The cyclomaltodextrinase gene was cloned on a 3-kb EcoRI fragment into the plasmid vector pPL708, and the fragment was structurally maintained in the host B. subtilis YB886. The cloned gene product was synthesized in an enzymatically active form in the B. subtilis host; however, expression was at a low level. Subcloning of the 3-kb EcoRI fragment into pUC18 and transformation into E. coli XL1-Blue (F' lacIq) indicated that the cyclomaltodextrinase gene was cloned with its own promoter, since expression of the gene occurred in the absence of IPTG. Subcloning of the cyclomaltodextrinase gene downstream from the Bacillus temperature phage SPO2 promoter of pPL708 may increase expression of this gene.

Identification of Staphylococcus epidermidis and Staphylococcus hominis from blood cultures by testing susceptibility to desferrioxamine

Testing susceptibility to desferrioxamine has recently been described as a method for the identification of Staphylococcus epidermidis. This method was compared to a commercial test and the tube coagulase test for the identification of staphylococci from blood cultures and other fluid specimens. A total of 216 isolates was tested over a 13-month period. Sensitivity of the desferrioxamine test in identifying isolates of Staphylococcus epidermidis and Staphylococcus hominis was 97.3%, while specificity was 91.8%. When isolates displaying discrepant desferrioxamine results were characterized using recently described interpretive criteria, sensitivity and specificity of the desferrioxamine test improved to 100%. The desferrioxamine test was reliable, inexpensive and simple to perform, and should prove useful in the diagnostic laboratory.

Post-translational modification of the tegument proteins (VP13 and VP14) of herpes simplex virus type 1 by glycosylation and phosphorylation

VP13 and VP14, major tegument proteins of herpes simplex virus type 1 (HSV-1) and the products of the UL47 gene, have been shown by partial proteolytic mapping to have closely related protein sequences. These proteins are phosphorylated in virus-infected cells, but not in preparations of purified virus. They also contain O-linked oligosaccharide units which include beta-1,4-N-acetyl galactosamine residues, as demonstrated by the binding of Dolichos biflorus lectin. This modification was detected only in purified virus and appears to be restricted to VP13/14 and VP22, another HSV-1 tegument protein.

Susceptibility to desferrioxamine: a new test for the identification of Staphylococcus epidermidis

The ability to identify Staphylococcus epidermidis quickly and accurately has become increasingly important in clinical microbiology. Susceptibility to desferrioxamine, an iron-chelating agent, was investigated as a new test for the identification of S. epidermidis. All strains of S. epidermidis and S. hominis tested were susceptible to a 1000-micrograms disk of desferrioxamine when grown on brain heart infusion agar. All other strains of coagulase-negative staphylococci, S. aureus and micrococci were resistant. As a single test, susceptibility to desferrioxamine was 96.4% efficient in identifying S. epidermidis; when combined with additional tests such as alkaline phosphatase production and fermentation of trehalose, the efficiency improved to 100%. Desferrioxamine disks were easy to prepare, stable and inexpensive. The test was simple to perform and interpret and should readily find application in clinical microbiology laboratories.

Evaluation of a Visual DNA Probe for Enterotoxigenic E. coli Detection in Foods and Wastewater by Colony Hybridization

A visual DNA probe for the detection of enterotoxigenic E. coli (LT EEC) by colony hybridization was evaluated to determine its efficacy as a more restrictive, routine indicator method for foods and wastewater. The E. coli heat labile enterotoxin (LT) gene was used as the DNA probe to detect LT EEC. In control experiments the reliability of the probe was demonstrated with food spiked with LT EEC. Raw oysters and wastewater examined for naturally occurring LT EEC showed significant levels of probe positive isolates. Despite some problems, for example background noise associated with food type, the DNA probe proved satisfactory as a method for indicating the presence of enterotoxigenic Enterobacteriaceae .

The effect of a Clostridium perfringens 8-6 enterotoxin on viability and macromolecular synthesis in Vero cells

Clostridium perfringens type A 8-6 enterotoxin causes gross morphological damage to Vero cells grown in tissue culture. Damage was observed to occur after only 30 minutes exposure at concentrations as low as 20 ng/ml, and within 60 minutes 95% of the cells had detached. Concentrations as low as 0.01 ng were able to cause detectable inhibition of plating efficiency. The enterotoxin inhibited DNA, RNA and protein synthesis and caused the reversal of glucose transport. Heat inactivated enterotoxin had no effect on cell function or morphology.

A scanning electron microscope study of the effect of an enterotoxin from Clostridium perfringens 8-6 on mice of different ages

Intestinal damage to mice caused by an enterotoxin from a coatless spore mutant of Clostridium perfringens type A (8-6) was examined by scanning electron microscopy. Two distinct types of damage were observed, both of which could be correlated with animal age. Damage appeared to occur in a specific sequence similar to that found in previous studies in rabbits. We conclude that the type of ileal tissue damage reflects the mode of toxin incorporation from the gut, which is a function of animal age.

Protoplast water content of bacterial spores determined by buoyant density sedimentation

Protoplast wet densities (1.315 to 1.400 g/ml), determined by buoyant density sedimentation in Metrizamide gradients, were correlated inversely with the protoplast water contents (26.4 to 55.0 g of water/100 g of wet protoplast) of nine diverse types of pure lysozyme-sensitive dormant bacterial spores. The correlation equation provided a precise method for obtaining the protoplast water contents of other spore types with small impure samples and indicated that the average protoplast dry density was 1.460 g/ml.

Purification and properties of an enterotoxin from a coatless spore mutant of Clostridium perfringens type A

A method is described for isolating an enterotoxin from a coatless spore mutant (8-6) of Clostridium perfringens type A. The characteristics of this enterotoxin only slightly resembled those of previously isolated enterotoxins of C. perfringens. The type A (8-6) enterotoxin was found to be composed of two subunits of Mr 18 000 with isoelectric points of 3.8 and 4.3. The LD50 for mice was 39 micrograms/kg with 0.10 micrograms corresponding to one erythemal unit. The type A (8-6) enterotoxin was inactivated by heating for 10 min at 60 degrees C. The amino acid composition data of type A (8-6) and delta toxins was similar, but type A (8-6) and type A enterotoxins showed less similarity. This lack of similarity between type A and type A (8-6) enterotoxins was confirmed by the failure of anti-sera to type A enterotoxin to neutralize the type A (8-6) enterotoxin, in both the mouse and erythemal tests.

A comparison of UV induced DNA photoproducts from isolated and non-isolated developing bacterial forespores

UV-induced photoproduct formation has been compared in non-isolated and isolated developing forespores. We have found that levels of spore type photoproducts are greatly affected by mother cell DNA. We have also observed the presence of the photoproduct 6-4'-(pyrimidin-2'-one)-thymine in developing forespores. We conclude from these and other data in the literature that the degree of hydration around the forespore DNA is reduced by the presence of dipicolinic acid which influences photoproduct formation without causing a change in conformational state.

A method for the isolation of intact, viable forespores from Bacillus species using high pressure

Large-scale preparation of Bacillus forespores was performed using nitrogen gas under high pressure to force an osmotically stable spheroplast suspension through a micrometer needle valve. Ninety-nine percent recovery of intact viable forespores at various stages of sporulation was achieved with a variety of Bacillus species. The isolated forespores are stable for up to 7 days when kept under nongerminating conditions.

Scanning electron probe x-ray microanalysis of elemental distributions in freeze-dried cryosections of Bacillus coagulans spores

High-resolution scanning electron probe X-ray microanalysis had been employed to examine elemental distributions in freeze-dried cryosections of Bacillus coagulans spores. Calcium, manganese, and phosphorus were concentrated in the protoplast and the coat. Iron was found in the coat but not in the protoplast, whereas the silicon seen on the coat of other spore species was absent. Sulfur was present in the coat, but was distributed over a broader area than the other elements, which suggested that phosphorus and the metal ions were located in the outer coat layer.

Effects of activated carbon and bacteriostatic filters on microbiological quality of drinking water

Three activated carbon filters for point-of-use water treatment were tested in laboratory and field studies for chemical removal and microbiological effects on water. All removed free available chlorine in municipally treated water to below the limit of detection, but removed only about 50 to 70% of the total available chlorine and 4 to 33% of the total organic carbon. Standard plate count bacteria in the effluent increased steadily with time for 3 weeks and remained elevated over the 8-week period of the study. Total coliform bacteria were found to persist and proliferate on the filters for several days after transient contamination of the influent water. Silver-containing activated carbon filters suppressed total coliform but not total bacterial growth. Pseudomonas aeruginosa was recovered from the effluents of all filters at some time during the tests.

Distribution of calcium and other elements in cryosectioned Bacillus cereus T spores, determined by high-resolution scanning electron probe x-ray microanalysis

The distribution of a number of key elements in Bacillus cereus T spores was determined by high-resolution scanning electron probe X-ray microanalysis. To circumvent the redistribution of soluble or weakly bound elements, freeze-dried cryosections of spores, which had been rapidly frozen in 50% aqueous polyvinyl pyrrolidone, were employed. The sections were examined by using a modified Philips EM400 electron microscope fitted with a field emission gun, scanning transmission electron microscopy attachment, and a computer-linked energy-dispersive X-ray microanalysis system. X-ray maps for selected elements and the corresponding electron image were produced simultaneously by scanning the cryosections with a fine electron beam in a raster pattern, using the scanning transmission electron microscopy attachment. The results indicated that almost all of the calcium, magnesium, and manganese, together with most of the phosphorus, was located in the core region. An unexpectedly high concentration of silicon was found in the cortex/coat layer. Granules containing high concentrations of calcium, manganese, and phosphorus were demonstrated in spores containing reduced levels of dipicolinic acid. Spot mode analyses, in which a stationary beam was located over the region of interest in the spore cryosection, confirmed the results obtained with the scanning mode and also provided a more accurate quantitation of the elemental concentrations on a dry weight bases.

Image intensifier as an aid to insertion of the Zickel nail apparatus for proximal femoral fractures

Technical problems have been encountered when using the usual method of implanting the Zickel nail. We have attempted to overcome them by placing the patient on an orthopaedic table and screening the femur using an image intensifier. The results, and the particular ways in which this technique has helped, are described.

Purification and properties of histidinol dehydrogenases from psychrophilic, mesophilic and thermophilic bacilli

As a first step in elucidating one molecular mechanism of adaptation to life at extreme temperatures, we purified and characterized the enzyme histidinol dehydrogenase (EC 1.1.1.23) from a number of bacilli whose growth temperatures range from 5 degrees t to 90 degrees C. The enzymes were purified by (NH4)2SO4 precipitation, ion-exchange chromatography on Sephadex, affinity chromatography on histamine- or histidine-Sepharose and preparative gradient gel electrophoresis. All had similar mol.wts. (29200), sedimentation coefficients (S20,w 2.56S), affinities for histidinol and NAD+ (Km = 48 micron and 0.2 mM respectively) and all had pH optima at 9.6. Marked differences were observed in stability with respect to temperature and the temperature at which the initial velocity for histidinol dehydrogenation was optimal. These optima range from 25 degrees C for the enzyme from the psychrophilic species through to 41 degrees C for the mesophiles to 85-92 degrees C for the extreme thermophiles. It is concluded that the ability of the enzymes to operate at their various optimum temperatures is an intrinsic property of their amino acid sequences.