Blood lead levels in children in Perth,Western Australia

Abstract: This study reports on an analysis of the lead concentrations in 123 venous blood samples collected from Perth children aged between two months and 17 years attending Princess Margaret Hospital. The overall geometric mean was 6.9 μg lead per 100 ml whole blood, with 95 per cent of results lying between 3.2 and 14.8 μg/100 ml. Among children under five years of age, those aged between 18 months and two years had the highest geometric mean blood lead (11.1 μg/100 ml). There were no consistent associations between geometric mean blood lead and area of residence, age group or sex. In this sample of Perth children, the mean blood lead concentration was lower than those reported in other studies. Less than 0.1 per cent of children of the age range studied would have been expected to have lead levels exceeding the NHMRC ‘level of concern’ (25 μg/100 ml) current at the time of the study. However, the recent adoption of goal of less than 10 μg/100 ml could mean that lead levels in up to 21 per cent of Perth children would now be regarded as excessive.     

Serpentine aneurysm of the posterior circulation: report of two cases

Giant serpentine aneurysms form a subgroup of giant intracranial aneurysms with specific radiological and surgical features. Previous reports have stressed the predilection of these lesions for the carotid circulation, particularly the middle cerebral artery. Two cases of serpentine aneurysm affecting the posterior circulation are reported and the problems of diagnosis and treatment of this lesion are discussed.     

Reversible reorganisation of the motor cortical representation of the hand in cervical dystonia.

Previous work has suggested that there may be a widespread disturbance of motor control mechanisms in patients with cervical dystonia. In the present study, we used transcranial magnetic stimulation to investigate the topography of the corticomotor projection to the abductor pollicis brevis (APB) muscle in 10 subjects with idiopathic torticollis. Threshold-adjusted stimuli were delivered at multiple scalp sites during a low-level voluntary contraction of the APB, and maps were generated of motor evoked potential amplitude versus scalp site. The cortical maps for the APB on the side opposite to the direction of head rotation were displaced laterally or posteriorly in all subjects and reverted to a more normal position after botulinum toxin injection of the cervical muscles in 5 subjects. The findings point to a reversible reorganisation of the corticomotor representation of the hand on the same side as the sternocleidomastoid (SCM) muscle that is involved in producing the dystonia. These results provide further evidence for the involvement of cortical centres and for a more widespread abnormality of motor control mechanisms in focal dystonia. The findings also support the notion that head turning is chiefly mediated by the hemisphere ipsilateral to the direction of the head rotation by means of a corticomotor projection to the contralateral SCM.     

Lymphocytotoxins in infectious mononucleosis: a non-cytotoxic effect on their cytotoxicity in vitro

The lymphocytotoxic activity (LCA) of sera from patients with infectious mononucleosis (IM) was tested against lymphocytes under various experimental conditions. Firstly, lymphocytes from 11 healthy donors were preincubated with pools of normal human sera (NHS) or IM sera at 37°C and then tested for (a) reactivity with the same IM sera in a standard lymphocytotoxin assay at 15°C; (b) rosetting with various sheep erythrocyte (E) preparations (E, EA and EAC) and (c) stimulation by non-specific activators (phytohaemagglutinin, pokeweed mitogen and concanavalin A). These experiments showed that preincubation of normal cells with IM sera caused significant reduction in subsequent lymphocyte killing at 15°C (P<0·01) compared to unincubated cells or those preincubated with pooled NHS. There was no change in the binding of E, EA and EAC or mitogen stimulation following incubation. Culture of preincubated lymphocytes in lymphocytotoxin-free medium for 24 hr did not restore LCA at 15°C. Secondly, a pool of normal lymphocytes was incorporated into media containing either 2,4-dinitrophenol or sodium azide and tested for LCA against 11 acute IM sera and two NHS at both 15 and 37°C. No significant change in cell killing was observed at 15°C in the presence of these inhibitors, but there was a significant return of LCA at 37°C. Finally, normal lymphocytes and cells from two patients with IM were cultured at 37°C in lymphocytotoxin-free medium to determine the role of down-regulation of lymphocyte surface receptors in reducing autolymphocytotoxicity during the acute phase of the illness. There was no change in cell killing by IM sera after culture for 24 hr. These experiments show that lymphocytotoxic sera from patients with infectious mononucleosis interact with normal lymphocytes at 37°C without causing cell killing. This interaction caused a change in surface-binding characteristics that was not reversed by culture in ligand-free medium for 24 hr. Studies using metabolic inhibitors suggested that the failed lymphocytotoxicity at 37°C resulted, at least in part, from lymphocyte metabolism, although this did not inhibit the reaction between cytotoxic material and the lymphocyte surface.     

Evidence for thiocyanate-sensitive peroxidase activity in human saliva.

A procedure was developed for determining the relative levels of lactoperoxidase, leukocyte myeloperoxidase, and thiocyanate-sensitive peroxidase in human saliva. With this procedure, most of the peroxidase activity in whole saliva from normal (those without cancer) subjects was found to be associated with lactoperoxidase and thiocyanate-sensitive peroxidase, with only a minor contribution from leukocyte myeloperoxidase. In contrast, thiocyanate-sensitive peroxidase and leukocyte myeloperoxidase were the major peroxidase activities present in the residual salivary secretion obtainable from two xerostomic patients examined, and these enzymes were present at concentrations much higher than those normally occurring in human saliva. The occurrence of thiocyanate-sensitive peroxidase in saliva has not been previously reported and may represent either an additional peroxidase activity of saliva or a form of lactoperoxidase which is particularly sensitive to inhibition by thiocyanate.     

Serum creatine kinase activity following forearm flexion isometric exercise

Summary The purpose of this study was to 1) compare serum creatine kinase (CK) activity following two forearm flexion isometric exercise regimens differing in work to rest ratio, and 2) examine the CK response to a repeated bout of isometric exercise. Eleven males were tested on two sessions (bouts) spaced 1 week apart. For bout 1, five subjects (group A) performed a forearm flexion isometric exercise consisting of 40 10-s maximal contractions with 20-s inter-trial rests (1020), while six (group B) performed 40 maximal 10-s contractions with 5-s inter-trial rests (105). The increase in serum CK activity following the 1020 exercise (143%) was significantly greater than that following the 105 exercise (52%). The 1020 exercise was also associated with greater tension generation over trials. One week later, both groups performed a bout of 1020 exercise. A substantial reduction in the serum CK response was found following this second bout. The data suggest that for bout 1 the isometric exercise associated with the greater overall tension levels resulted in the greater CK response. However, when the 1020 exercise was repeated 1 week later, a substantial reduction in the CK response was found which was unrelated to the tension generated.This study was supported by a University Faculty Research Grant No. 2-03021     

Cytomegalovirus detection by biotinylated DNA probes

Clinical specimens from 317 patients suspected of cytomeglovirus infection were examined by immunofluorescence (IF) using monoclonal antibodies and by a biotinylated DNA probe kit after cell culture isolation. Of the 317 samples, 68 were positive by culture isolation. Of these 67 were IF positive when the cytopathic effect (CPE) was 1⁺ or less, whereas 56 gave positive results with DNA probes when the CPE was 2⁺. A further 83 specimens were examined directly by immunoperoxidase histopathology (IHP), IF and the DNA probe kit: 26 of these were positive by IHP examination, 25 by IF and only 6 by DNA probes. The sensitivity of the DNA probe kit was not satisfactory when the clinical tissue specimens were directly examined. However, the sensitivity improved considerably to 82% if the specimens were propagated first in cell culture. The IF method detected the virus before and after cell culture isolation equally well (96%–98.5%). Compared to the IF method, the DNA probe kit is costly and requires more labor and time.This paper was presented in part at the 88th annual meeting of the American Society for Microbiology, Miami Beach, FL, USA, 1988