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The natural history of many entomopathogenic nematode species remains unknown, despite their wide commercial availability as biological control agents. The ambushing entomopathogenic nematode, Steinernema carpocapsae, and the introduced European earwig, Forficula auricularia, forage on the soil surface. Since they likely encounter one another in nature, we hypothesized that earwigs are susceptible to nematode infection. In the laboratory, the LC(50) for F. auricularia was 226 S. carpocapsae/earwig and the reproductive potential was 123.5 infective juvenile nematodes/mg tissue. This susceptibility depended on host body size with significantly higher mortality rates seen in larger earwigs. In a study of host recognition behavior, S. carpocapsae infective juveniles responded to earwig cuticle as strongly as they did to Galleria mellonella cuticle. We also found that earwigs exposed to S. carpocapsae cleaned and scratched their front, middle and back legs significantly more than controls. Coupled with previous field data, these findings lead us to suggest that F. auricularia may be a potential host for S. carpocapsae.

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SSADH deficiency, a rare inborn error of human metabolism, disrupts the normal metabolism of the inhibitory neurotransmitter GABA. In response to the defect, physiologic fluids from patients accumulate GHB, a compound with numerous neuromodulatory properties. Clinical and bio-chemical findings in patients are contrasted with existing neuropharmacologic data on GHB in animals and men. We conclude that GHB contributes to the pathogenesis of SSADH deficiency; whether this effect is mediated by GHB, by GABA following metabolic interconversion, or via synergistic mechanisms by both compounds, remains to be determined. An animal model of SSADH deficiency should further define the role of GHB in the pathogenesis of SSADH deficiency, and provide a useful vehicle for the evaluation of new therapeutic intervention.

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A quantitative assay for 4-hydroxybutyric acid was developed using D6-4-hydroxybutyric acid as an internal standard. 4-Hydroxybutyric acid was isolated by liquid chromatography and the amount quantified by selected ion monitoring, ammonia chemical ionization gas chromatography/mass spectrometry of the trimethylsilyl derivatives. The concentrations of 4-hydroxybutyric in control physiological fluids were: 2.64 +/- 3.46 mmol mol-1 creatinine in urine, 1.09 +/- 2.87 mumol l-1 in plasma, 0.98 +/- 1.17 mumol l-1 in cerebrospinal fluid and 1.28 +/- 0.47 mumol l-1 in amniotic fluid. The concentration of 4-hydroxybutyric acid in the amniotic fluid from a pregnancy at risk for 4-hydroxybutyric aciduria was 2.30 mumol l-1, indicating an unaffected fetus. The stable isotope dilution assay of 4-hydroxybutyric acid in physiological fluid samples is a rapid, sensitive and accurate method for quantification, as well as a valuable technique for the prenatal diagnosis of 4-hydroxybutyric aciduria.

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Giant axonal neuropathy (GAN) is a distal sensorimotor neuropathy, characterized by neurofilamentous axonal swellings, with usual onset at 2 to 3 years of age. We report a case of congenital GAN with hypotonia at birth. At 7 months of age, nerve conduction studies showed almost complete lack of sensory and motor responses in the lower extremities. A sural nerve biopsy specimen disclosed absence of myelinated axons. Autopsy, following death at 15 months of age, revealed axonal swellings in peripheral nerves and distal degeneration of long spinal cord tracts. The neurofilamentous content of the axonal swellings was confirmed by Glees-Marsland staining and immunoperoxidase reaction with antibodies to neurofilaments. Axonal swellings did not stain with periodic acid-Schiff and were not seen in the cerebral cortex or brain stem, distinguishing this process from infantile neuroaxonal dystrophy. This patient illustrates congenital GAN with subsequent rapid progression.

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An acute Guillain-Barré syndrome presenting as dysautonomia is described in a 12-year-old boy. The patient died of intractable cardiac arrhythmias and cardiac failure. A severe myocarditis with destruction of dorsal root ganglion cells and wallerian degeneration of dorsal roots and peripheral nerves was apparent postmortem. Segmental demyelination and inflammatory cellular infiltrations were not present at these sites.

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Regional cerebral blood flow was measured by the xenon 133-inhalation method in a 40-year-old man during an acute exacerbation of intracranial vasculitis. Neurologic function was quantitated by the Halstead-Reitan Neuropsychological test battery. The patient was also studied during remission that was induced by steroid therapy. Vasculitis produced a diffuse encephalopathy with generalized reduction in cerebral blood flow. During remission, only local symptoms secondary to a small cerebral infarction remained and regional cerebral blood flow returned to the normal range. There seems to be a close correlation between the severity of symptoms in cerebral vasculitis and reduction of flow through diseased vessels.

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A 9-year-old girl had an acute encephalopathic illness characterized by disordered consciousness, seizures, and multiple cortical deficits. The acute illness was associated with serologic evidence of an antecedent streptococcal infection and the presence of a mixed cryoglobulin with specific antistreptococcal antibody activity. Although the patient had no other evidence of a systemic or central nervous system vasculitis, computerized tomography demonstrated changes compatible with a vasculitic process. Treatment with corticosteroids was associated with resolution of the cryoglobulinemia and complete clinical recovery.

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