Computed tomography of the post-operative lumbar spine: the need for, and optimal dose of, intravenous contrast medium

Forty-five patients who had undergone previous lumbar spine surgery with symptoms and signs warranting further investigation were examined by computed tomography (CT). The findings in three separate subgroups of 15 patients were compared. The first randomly selected group underwent CT without the use of intravenous contrast medium; the second and third groups were examined both before and after the administration of contrast medium, using 16.25 g and 32.5 g iodine, respectively. In the latter two groups the CT studies were reported both before and after enhancement. In the 15 patients in the first group (no contrast medium), uncertainty as to whether disc material or fibrosis was responsible for the radiological abnormalities was expressed in the final report at six of the 20 post-surgical sites. Among the 30 patients who received contrast medium, 40 post-surgical sites were examined; at six of these sites there was no radiological cause for concern; at 16 sites there were unequivocal radiological appearances of either disc material or fibrosis. Enhancement resolved the radiological uncertainty at 13 of the remaining 18 sites, almost always by reinforcing the initial radiological opinion; this left five sites where uncertainty persisted in the final report. The larger dose of contrast medium caused the more marked enhancement of those abnormalities considered to be due to fibrosis, although enhancement was readily recognised using the lower dose. While intravenous enhancement assists radiological interpretation at those sites where diagnostic uncertainty persists after routine CT, it would seem that it is not essential in patients in whom routine CT studies show no serious abnormality or the characteristic appearances of disc material or fibrosis.     

Anaerobic infections of the urinary tract: are they being missed?

Routine anaerobic culture of urine identified the urinary tract as the primary focus of sepsis in a postoperative patient with Bacteroides fragilis septicaemia. Specimens of urine from six other symptomatic patients grew > 10(8) cfu/litre of a Bacteroides species in pure growth. The significance of these isolates is discussed. Multipoint technology and the availability of anaerobic work stations have facilitated anaerobic culture and reduced its cost. The incorporation of anaerobic culture of urine into routine laboratory practice may be clinically valuable and should be considered.     

Modification of peanut allergen Ara h 3: effects on IgE binding and T cell stimulation

BACKGROUND: Peanut allergy is a major health concern due to the increased prevalence, potential severity, and chronicity of the reaction. The cDNA encoding a third peanut allergen, Ara h 3, has been previously cloned and characterized. Mutational analysis of the Ara h 3 IgE-binding epitopes with synthetic peptides revealed that single amino acid changes at critical residues could diminish IgE binding. METHODS: Specific oligonucleotides were used in polymerase chain reactions to modify the cDNA encoding Ara h 3 at critical IgE binding sites. Four point mutations were introduced into the Ara h 3 cDNA at codons encoding critical amino acids in epitopes 1, 2, 3 and 4. Recombinant modified proteins were used in SDS-PAGE/Western IgE immunoblot, SDS-PAGE/Western IgE immunoblot inhibition and T cell proliferation assays to determine the effects of these changes on in vitro clinical indicators of peanut hypersensitivity. RESULTS: Higher amounts of modified Ara h 3 were required to compete with the wild-type allergen for peanut-specific serum IgE. Immunoblot analysis with individual serum IgE from Ara-h-3-allergic patients showed that IgE binding to the modified protein decreased approximately 35-85% in comparison to IgE binding to wild-type Ara h 3. Also, the modified Ara h 3 retained the ability to stimulate T cell activation in PBMCs donated by Ara-h-3-allergic patients. CONCLUSIONS: The engineered hypoallergenic Ara h 3 variant displays two characteristics essential for recombinant allergen immunotherapy; it has a reduced binding capacity for serum IgE from peanut-hypersensitive patients and it can stimulate T-cell proliferation and activation.     

Stress-induced C-fos expression in the rat locus coeruleus is dependent on neurokinin 1 receptor activation

These experiments examined the role of substance P-selective neurokinin 1 receptors in the restraint-induced activation of the rat locus coeruleus. Immunohistochemistry revealed high levels of neurokinin 1 receptor expression in the plasma membrane of tyrosine hydroxylase-positive locus coeruleus neurons. The selective neurokinin 1 receptor antagonists, RP 67580 (5 nmol) and L-760,735 (3.4 nmol), were administered intracerebroventricularly prior to restraint stress, and c-fos protein was measured as an index of locus coeruleus activation. Both antagonists attenuated the restraint-induced increase in locus coeruleus c-fos expression, whereas their inactive enantiomers were ineffective. These results suggest that neurokinin 1 receptors may mediate activation of locus coeruleus neurons during stress. Neurokinin 1 receptor antagonists may prove to be novel therapeutic compounds in the treatment of anxiety and depression.     

Presynaptic dopamine receptors: Insensitivity to kainic acid and the development of supersensitivity following chronic haloperidol

Summary The effects of kainic acid lesions and chronic haloperidol treatment on rat striatal dopaminergic presynaptic receptors were studied. Following the -butyrolactone-induced inhibition of dopaminergic impulse flow, and after dopa decarboxylase inhibition, dopa accumulation and its reversal by dopamine agonists was measured in vivo.³H-apomorphine (a dopamine receptor ligand with purported presynaptic specificity) was used for in vitro binding experiments. Presynaptic dopamine receptors, as assessed by both methods, were unaffected by intrastriatal kainic acid injection 5–6 days before sacrifice. Seven days after termination of chronic haloperidol treatment (28 days, 0.5 mg/kg/day s.c.) both an increased apomorphine response using the dopa accumulation method and an increase in³H-apomorphine binding were observed, indicating the development of presynaptic dopamine receptor supersensitivity.