In-flight disinsection as an efficacious procedure for preventing international transport of insects of public health importance

Aircraft disinsection with aerosol insecticides during flight has generally been held to be inadvisable because it was assumed that the insecticides would be rapidly removed by the cabin air-conditioning system. We have developed protocols to deliver 2% d-phenothrin at a dose of 35 g per 100 m3 in various aircraft, and trials undertaken on Boeing 747 and 767 aircraft showed that their air-conditioning systems do not preclude effective disinsection. Mortality levels of 100% for Culex quinquefasciatus and Musca domestica test insects were recorded under normal operating conditions during routine scheduled passenger flights with disinsection procedures undertaken at "blocks-away" or at "top-of-descent". As a result, "top-of-descent" disinsection has been introduced as the recommended procedure for aircraft landing in Australia.     

Platelet function in hairy-cell leukaemia

A quantitative study of various aspects of platelet function was carried out in eight patients with typical hairy-cell leukaemia (HCL). In at least two patients platelet aggregation was convincingly reduced to more than one aggregating agent (ADP, adrenaline, collagen, thrombin, and ristocetin). Granular storage capacity for {(14)C} 5-HT was reduced in five of the six patients tested. The two patients with definitely abnormal aggregation had the greatest reduction in granular storage pool and the longest bleeding times of those tested but, like the other patients, they did not have a clinical haemostatic defect. It was concluded that a granular storage pool defect (SPD) was at least partly responsible for aggregation abnormalities in HCL since the platelet release reaction in response to thrombin appeared to be normal. All our patients ran a chronic course uncomplicated by any of the factors known to predispose to a platelet SPD acquired in the circulation. Although in the one patient tested before and after splenectomy there was some improvement in platelet aggregation after operation, there was no clear general relationship between defective platelet function and either previous splenectomy or platelet count. Since a direct involvement of the megakaryocytic series in the underlying cell proliferation of HCL seems unlikely, it is concluded that the platelet defect can most reasonably be attributed to the production of abnormal platelets as a result of marrow fibrosis and/or infiltration by hairy cells.     

Multiplex PCR for direct detection of Shiga toxigenic Escherichia coli strains producing the novel subtilase cytotoxin

We have recently described a novel AB₅ subtilase cytotoxin produced by certain Shiga toxigenic Escherichia coli (STEC) strains. This potentially lethal toxin may contribute to severe gastrointestinal and systemic disease in humans. In this study we have developed a trivalent PCR assay for the detection of the novel toxin A subunit gene subA, as well as stx₁ and stx₂. The three primer pairs used in the assay do not interfere with each other and generate amplification products of 556, 180, and 255 bp, respectively. The assay can be used for determining the toxin genotype of STEC isolates, as well as for direct detection of toxin genes in primary fecal culture extracts.     

Detection and Characterization of Shiga Toxigenic Escherichia coli by Using Multiplex PCR Assays for stx1, stx2, eaeA, Enterohemorrhagic E. coli hlyA, rfbO111, and rfbO157

Shiga toxigenic Escherichia coli (STEC) comprises a diverse group of organisms capable of causing severe gastrointestinal disease in humans. Within the STEC family, certain strains appear to be of greater virulence for humans, for example, those belonging to serogroups O111 and O157 and those with particular combinations of other putative virulence traits. We have developed two multiplex PCR assays for the detection and genetic characterization of STEC in cultures of feces or foodstuffs. Assay 1 utilizes four PCR primer pairs and detects the presence of stx₁, stx₂ (including variants of stx₂), eaeA, and enterohemorrhagic E. coli hlyA, generating amplification products of 180, 255, 384, and 534 bp, respectively. Assay 2 uses two primer pairs specific for portions of the rfb (O-antigen-encoding) regions of E. coli serotypes O157 and O111, generating PCR products of 259 and 406 bp, respectively. The two assays were validated by testing 52 previously characterized STEC strains and observing 100% agreement with previous results. Moreover, assay 2 did not give a false-positive O157 reaction with enteropathogenic E. coli strains belonging to clonally related serogroup O55. Assays 1 and 2 detected STEC of the appropriate genotype in primary fecal cultures from five patients with hemolytic-uremic syndrome and three with bloody diarrhea. Thirty-one other primary fecal cultures from patients without evidence of STEC infection were negative.     

Quantities of Clostridium botulinum organisms and toxin in feces and presence of Clostridium botulinum toxin in the serum of an infant with botulism.

A 7-week-old boy presented with symptoms and signs characteristic of infant botulism, and the diagnosis was confirmed by the detection of Clostridium botulinum type A organisms and toxin in the feces. The levels of organisms and toxin in the feces were measured throughout the 81-day period in hospital. The maximum levels detected were 2.46 x 10(8) C. botulinum type A colony-forming units and 64,000 mouse 100% lethal doses of type A toxin per g (wet weight) of feces. C. botulinum toxin was also detected in two samples of the patient's serum, collected 3 and 10 days after admission. Improvement in the patient's clinical condition occurred before the levels of organisms and toxin in the feces reached their maxima. A slight improvement may also have occurred while toxin was still present in the serum.     

Accumulation and defective β-oxidation of very long chain fatty acids in Zellweger''s syndrome, adrenoleukodystrophy and Refsum''s disease variants

The accumulation of very long chain fatty acids in plasma and skin fibroblasts was measured in at least four separate inherited disease states. Both the magnitude and the nature of the fatty acid changes reflected the clinical status of individual patients. In Zellweger's syndrome, and to a lesser extent in infantile Refsum's disease, there was an increase in 24:0, 26:0, 26:1, and a number of even longer chain fatty acids, while in the X-linked form of adrenoleukodystrophy these changes were less pronounced. Zellweger fibroblasts in culture took up lignoceric, phytanic and stearic acids and incorporated them into a variety of lipids in a manner comparable to control fibroblasts. However, these cells were unable to convert phytanic or lignoceric acid to CO2. Infantile Refsum's and X-linked adrenoleukodystrophy fibroblasts showed normal conversion of these acids to CO2. Normal fibroblast homogenates produced radioactive acetate from [1-14C] stearic and [1-14C] lignoceric acids indicating that both substrates were beta-oxidised under these conditions. Homogenates of fibroblasts from all patients patients with biochemical evidence of accumulation of very long chain fatty acids showed normal or near-normal stearic acid beta-oxidation, but were deficient in lignoceric acid beta-oxidation. Residual lignoceric acid beta-oxidation activity varied from approximately 15% in Zellweger syndrome up to 50% in X-linked adrenoleukodystrophy. It is postulated that the accumulation of very long chain fatty acids results from defects in peroxisomal beta-oxidation. In Zellweger's syndrome, and possibly in infantile Refsum's disease, it is probable that this defect is secondary to a primary abnormality affecting the structure and/or function of peroxisomes, while the primary defect in X-linked adrenoleukodystrophy may be confined to a pathway specific for the oxidation of very long chain fatty acids.