Assessment of dermal exposure--empirical models and indicative distributions

The Health and Safety Executive embarked upon a program of work to address the issue of exposure to nonagricultural pesticides in the United Kingdom. Early on it became clear that the primary route of exposure was via the skin. Empirical dermal exposure models have been developed which allow estimates of potential dermal exposure to be derived from distributions of rate of contamination with in-use formulations during typical use conditions in the workplace. Estimates of actual dermal exposure (what gets onto the skin) may also be anticipated and used in quantitative risk assessment to inform product registration. The key interpreted data from the empirical models are presented. Data are presented for six models. Separate summary data are presented for exposure to the body, hands, and feet. In the case of hand exposure, data are presented, in some cases, for contamination arising from wearing used (previously worn, of unknown history) and clean protective gloves. This article proposes a mechanism for addressing exposure assessment where little or no direct dermal exposure data are available--the indicative distribution approach. The empirical distributions of rate of contamination have been studied to seek commonalities which may allow the construction of a universal tool for use in screening level risk assessment. A simple 12-box matrix is proposed.

Potential exposure of hands inside protective gloves-a summary of data from non-agricultural pesticide surveys

The results of individual surveys are compared and general observations are made about the protective nature of protective gloves. A total of 190 measurements of contamination by involatile components of pesticide products were made inside the gloves. Protective gloves were nearly always found to be contaminated inside, except for public hygiene insecticide uses. Disposable gloves were sometimes used when applying public hygiene insecticides, while gloves worn for other applications were normally re-used. The data suggest that when expressing inner glove exposure as 'amount of product per unit time', the data distributions of the non-zero results appeared similar for all activities except for the application of antifoulings. A median value for all non-zero data was indicated at 1.36mg product per minute; a 75th percentile at 4.21mg min(-1) and a 95th percentile at 71.9mg min(-1), assuming product densities of 1.0g ml(-1). In default of better information, these indicators can be used in health-based risk assessment. A further 47 data related to exposure inside new gloves, and 21 data to deposition on outer gloves. These indicate that in general, gloves provide a reasonable degree of protection to non-agricultural pesticides. Due regard should be paid to 'human factors' when considering contamination inside gloves. When people take off dirty gloves, it is difficult to avoid touching the glove exterior. With gloves off, the subject can touch contaminated surfaces. Donning dirty gloves furnishes an inevitable contact with contamination on the outside of the gloves, and can introduce that contamination inside. A common mode of contamination could contribute to the similar distributions for hand contamination inside gloves, from very different uses.

The products of the Drosophila stoned locus interact with synaptic vesicles via synaptotagmin

The stoned locus of Drosophila melanogaster encodes two novel proteins, stonedA (STNA) and stonedB (STNB), both of which are expressed in the nervous system. Flies with defects at the stoned locus have abnormal behavior and altered synaptic transmission. Genetic interactions, in particular with the shibire (dynamin) mutation, indicated a presynaptic function for stoned and suggested an involvement in vesicle cycling. Immunological studies revealed colocalization of the stoned proteins at the neuromuscular junction with the integral synaptic vesicle protein synaptotagmin (SYT). We show here that stoned interacts genetically with synaptotagmin to produce a lethal phenotype. The STNB protein is found by co-immunoprecipitation to be associated with synaptic vesicles, and glutathione S-transferase pull-downs demonstrate an in vitro interaction between the micro2-homology domain of STNB and the C2B domain of the SYTI isoform. The STNA protein is also found in association with vesicles, and it too exhibits an in vitro association with SYTI. However, we find that the bulk of STNA is in a nonmembranous fraction. By using the shibire mutant to block endocytosis, STNB is shown to be present on some synaptic vesicles before exocytosis. However, STNB is not associated with all synaptic vesicles. We hypothesize that STNB specifies a subset of synaptic vesicles with a role in the synaptic vesicle cycle that is yet to be determined.

Determination of spinosad and its metabolites in food and environmental matrices. 3. Immunoassay methods

Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and is effective on several classes of insects, especially Lepidopteran larvae. Spinosad is registered in many countries for use on a variety of crops, including cotton, corn, soybeans, fruits, and vegetables. Residue methods utilizing a magnetic particle-based immunoassay (IA) test kit have been developed and validated for determining spinosad in environmental and food matrices. These methods involve an extraction of the residues from the matrices with appropriate solvents. For some matrices, the sample extracts can be diluted and measured directly by IA without any cleanup. For other matrices, sample extracts are purified using liquid-liquid partitioning and/or solid phase extraction prior to measurement by IA. The methods determine the total residue of spinosad, which includes the active ingredients (spinosyns A and D) and several minor metabolites, including spinosyn B, spinosyn K, and N-demethylspinosyn D. The methods have validated limits of quantitation of 0.0001 microgram/mL in water, 0.05 microgram/g in sediment, and 0.010 microgram/g in crops, crop processed commodities, and animal tissues. This paper briefly summarizes the residue methodology and method validation data for spinosad in 34 food, feed, and environmental matrices.

The pathologic features and mechanism of traumatic dislocation of the hip

The term traumatic dislocation of the hip encompasses a heterogenous group of dislocations, and more commonly, fracture-dislocations which have been subclassified. The current study describes the pathologic features in terms of an anatomic description of the displaced parts of the joint and what is known of the associated injured structures in each of the subtypes. The events that lead to traumatic dislocation of the hip are well documented, but understanding of the mechanics of the injury can only be presumptive.

Brain stem stroke causing baroreflex failure and paroxysmal hypertension

BACKGROUND

Paroxysmal neurogenic hypertension has been associated with a variety of diseases affecting the brain stem but has only rarely been reported after brain stem stroke. The mechanism is thought to involve increased sympathetic activity and baroreflex dysfunction. We undertook microneurographic recordings of muscle sympathetic nerve activity (MNSA) during beat-to-beat blood pressure (BP) monitoring to investigate this hypothesis.

CASE DESCRIPTION

We investigated a 75-year-old woman who developed paroxysmal hypertension (BP 220/110 mm Hg) after a large left-sided medullary infarct. The paroxysms were triggered by changes in posture and were accompanied by tachycardia, diaphoresis, and headache. Serum catecholamines were substantially increased (norepinephrine level, 23.9 nmol/L 9 days after stroke; normal level, <3.8 nmol/L), and heart rate variability, measured by spectral analysis, was decreased in both low- and high-frequency domains (0.04 and 0.06 ms(2), respectively; normal level, 0.14+/-0.02 ms(2)). MNSA was increased in frequency (61 bursts per minute; normal level, 34+/-18 bursts per minute), and the burst amplitude was not inversely related to diastolic BP. BP and MNSA responses to cold pressor and isometric handgrip stimuli were intact.

CONCLUSIONS

Extensive unilateral infarction of the brain stem in the region of the nucleus tractus solitarius may result in partial baroreflex dysfunction, increased sympathetic activity, and neurogenic paroxysmal hypertension.

Presynaptic glutamic acid decarboxylase is required for induction of the postsynaptic receptor field at a glutamatergic synapse

We have systematically screened EMS-mutagenized Drosophila for embryonic lethal strains with defects in glutamatergic synaptic transmission. Surprisingly, this screen led to the identification of several alleles with missense mutations in highly conserved regions of Dgad1. Analysis of these gad mutants reveals that they are paralyzed owing to defects in glutamatergic transmission at the neuromuscular junction. Further electrophysiological and immunohistochemical examination reveals that these mutants have greatly reduced numbers of postsynaptic glutamate receptors in an otherwise morphologically normal synapse. By overexpressing wild-type Dgad1 in selected neurons, we show that GAD is specifically required in the presynaptic neuron to induce a postsynaptic glutamate receptor field, and that the level of postsynaptic receptors is closely dependent on presynaptic GAD function. These data demonstrate that GAD plays an unexpected role in glutamatergic synaptogenesis.

Acromioclavicular dislocation. Conservative or surgical therapy

A literature review was performed to clarify available information which influences decisions whether to advise a young adult patient to undergo surgery for a severely displaced acromioclavicular dislocation. Twenty-four papers were retrieved yielding 1172 patients of whom the mean followup for the 833 surgically treated patients was 43.7 months and not surgically treated was 60.4 months. Of the 24 papers, only five reported surgical and conservative outcomes; two of these papers used prospective randomized methodology and three used nonrandomized methodology. Fourteen papers reported surgical outcome only and five papers reported conservative outcome only. Overall, 88% of surgically treated patients and 87% of nonsurgically treated patients had a satisfactory outcome. Complications most commonly listed were (surgically treated versus nonsurgically treated): need for further surgery (59% versus 6%), infection (6% versus 1%), and deformity (3% versus 37%). Return to activity was no quicker with surgery. Pain was not any more common without surgery. Range of movement was more frequently normal or near normal without surgery (95% versus 86% if surgically treated) and so was strength (92% versus 87%). Meta-analysis of the four studies including data from surgical and conservative therapy showed on significant benefit from surgery. Power studies suggest that to show a statistically significant benefit from surgery, large studies would be required, which, given the relative incidence of these injuries, would probably be multicenter and therefore vulnerable to methodologic difficulties. There does not seem to be any reason to recommend an operative procedure to a patient with a Rockwood et al Type III injury based on the evidence currently available.

Orthopaedic surgery in hemophilic patients with human immunodeficiency virus

Patients registered at the author's hemophilia center between 1982 and 1994 were studied to establish whether major orthopaedic surgical procedures accelerate the fall of CD4 lymphocyte counts of patients with hemophilia who are infected with the human immunodeficiency virus, and whether patients who had surgery had different rates of development of acquired immune deficiency syndrome or death when compared with patients who did not have surgery. The patients were divided into four groups: Group 1, 22 patients who were human immunodeficiency virus positive undergoing orthopaedic surgery; Group 2, 89 patients who were human immunodeficiency virus positive not undergoing orthopaedic surgery; Group 3, 18 patients who were human immunodeficiency virus negative undergoing orthopaedic surgery; and Group 4, 135 patients who were human immunodeficiency virus negative not undergoing orthopaedic surgery. There was no significant difference between the rates of decline of CD4 lymphocyte counts for patients who were human immunodeficiency virus positive who underwent surgery when compared with human immunodeficiency virus positive patients who did not undergo surgery, nor was there any significant difference between the two human immunodeficiency virus negative groups. There were no significant differences in the rate of development of acquired immune deficiency syndrome or mortality rates between patients who had surgery and those who did not.

Identification of a gene family from Drosophila melanogaster encoding proteins with homology to invertebrate sarcoplasmic calcium-binding proteins (SCPS)

Using antibodies raised against the Drosophila Ca(2+)-binding protein DCABP-23, we have isolated two distinct cDNA clones that encode Ca(2+)-binding proteins of the invertebrate sarcoplasmic calcium-binding protein (SCP) family. Southern blot analysis of whole genomic DNA has shown that one of the clones, Dcabp-A.1, is present in more than one copy in the genome of the fly, and is located in the beta-heterochromatic region at cytological division 80 on chromosome III. The expression pattern of this transcript shows that it is present in the tubular but not the fibrillar muscles of the adult thorax. This expression pattern is consistent with this being a true SCP. In contrast, the expression pattern of the transcript corresponding to the second cDNA clone is exclusive to neural tissue. This transcript derives from a single copy gene, and is located at cytological position 89 D on chromosome III. Comparative analysis of the amino acid sequences from the proteins encoded by the two cDNAs with that of the original DCABP-23 protein indicates that the purified DCABP-23 contained mainly the DCABP-A.1 protein. The identification of members of the SCP family of proteins in Drosophila, will allow for a future genetic investigation of the function of these ubiquitous proteins.

Protective gloves for use in high-risk patients: how much do they affect the dexterity of the surgeon?

Twenty-five orthopaedic surgeons underwent eight motor and sensory tests while using four different glove combinations and without gloves. As well as single and double latex, surgeons wore a simple Kevlar glove with latex inside and outside and then wore a Kevlar and Medak glove with latex inside and outside, as recommended by the manufacturers. The effect of learning with each sequence was neutralised by randomising the glove order. The time taken to complete each test was recorded and, where appropriate, error rates were noted. Simple sensory tests took progressively longer to perform so that using the thickest glove combination led to the completion times being doubled. Error rates increased significantly. Tests of stereognosis also took longer and use of the thickest glove combination caused these tests to take three times as long on average. Error rates again increased significantly. However, prolongation of motor tasks was less marked. We conclude that, armed with this quantitative analysis of sensitivity and dexterity impairment, surgeons can judge the relative difficulties that may be incurred as a result of wearing the gloves against the benefits that they offer in protection.

Current techniques in total knee replacement: results of a national survey

A postal questionnaire was sent to all Fellows of the British Orthopaedic Association to obtain a census of total knee replacement (TKR) preferences in the United Kingdom; 1162 questionnaires were sent and 721 replies received. There were 92 Fellows who had retired or filled in the forms incorrectly, and 32 no longer perform TKR. Thus, 597 responded correctly, giving a 62% response rate. This gives an extrapolated total of 34,677 TKRs being implanted per year in the UK, with an average of 34.3 being performed by each surgeon per year. Only 9% perform more than 90 per year. There were 41 different prostheses in current use among the respondents to our questionnaire, of which five prostheses constituted 61% of the total. Cemented prostheses were used by 95.2%. Resurfacing of the patella was always carried out by 32%, while 19% never resurface it; the most common reason for doing so being patellofemoral arthropathy at operation. Intramedullary alignment was used for the femoral component in 86%, 76% preferred extramedullary alignment for the tibial component. Regarding cementing technique, 43% use pulsatile lavage, 9% used a cement gun, 88% dry the bone and 56% seal the hole made by the femoral alignment device in the femur before cementing. All components were cemented simultaneously by 65% and one at a time by 31%. Metal-backed tibial prostheses are now used by 98% of surgeons, modular tibial components being preferred by 80%. Metal-backed patellar components were used by 13%. An onlay type of patella was preferred by 51%. This survey highlights the great diversity of surgical practice in the UK, which may reflect uncertainty regarding best practice in total knee replacement.

Drosophila melanogaster contains both X-linked and autosomal homologues of the gene encoding calcineurin B

A transcription unit was identified in the 43E polytene band region of the second chromosome of Drosophila melanogaster (Dm) whose putative translation product has 85% amino acid (aa) identity with the B subunit of the calcineurin protein (CnB) from humans. Unlike the previously described intronless Dm CnB gene homologue, which is located within the 4F band region of the X chromosome, the coding region of this second CnB is found to be interrupted by three introns. Conceptual translation of both Dm CnB genes predict proteins of identical size that are 98% identical in aa sequence. Northern blot analyses indicate that Dm pupae and adults express two different CnB-encoding transcripts that are differentially regulated.

Hemophilic ankle arthropathy

Ankle arthropathy remains a frequent source of disability in the hemophilic patient. Bleeding into the ankle most commonly commences in the second decade, and, once established as a target joint, progressive damage leads to significant pain, stiffness, and deformity affecting general mobility and leisure and occupational pursuits. Review of cohorts of hemophilic patients at the Royal Free Hospital has monitored this deterioration and there is no evidence that, despite improvements in medical treatment, the pattern of insidious decline in hindfoot function has changed during the past 4 decades. Based on these observations, a combined clinical and radiologic scoring system has been developed, incorporating ankle specific features, such as talar tilt, tibial osteophytes, and talar dome flattening, which give a better correlation than traditional systems with objective measures, such as treadmill walking. There is no substitution for prophylactic treatment in arresting ankle function decline, and surgical interventions are rare. However, the types of potential procedures are numerous and choices must be made according to the degree of disability and state of overall damage to the joint and adjacent soft tissues.

Ipsilateral total shoulder and elbow prosthetic replacement in a patient with severe haemophilia B

Since factor replacement concentrates became widely available in the 1970s, total prosthetic replacement of joints in haemophilic patients has become increasingly common, with success particularly in the knee and hip. However, there has been no published series of elbow or shoulder replacements large enough to draw conclusions about the advisability of these procedures in this group of patients. We report a case of prosthetic replacement of the shoulder in a 58-year-old man with haemophilia B, and replacement of the elbow joint of the same limb 21 months later. The results are initially very encouraging, with no pain in either joint since the early post-operative period. There have been no bleeds into either joint since surgery. Ranges of movement are satisfactory. Follow-up is now 37 months for the shoulder and 16 months for the elbow.

Evaluation of three methods for the rapid identification of Staphylococcus aureus in blood cultures

A total of 445 blood cultures containing Gram-positive cocci in clusters were tested for the presence of Staphylococcus aureus with the Accuprobe, heat-stable thermonuclease, and latex agglutination using Staphaurex. The results show that the Accuprobe, thermonuclease, and Staphaurex correctly identified 95, 96, and 62 of the 100 specimens containing S. aureus. The corresponding specificity for the methods was 99.1%, 100%, and 98.5%, respectively.

A neural gene from Drosophila melanogaster with homology to vertebrate and invertebrate glutamate decarboxylases

Cross-species hybridization has been used to isolate a second Drosophila gene, with homology to a feline glutamate decarboxylase (Gad) cDNA. The gene differs in sequence, chromosomal location, and spatial expression from the previously reported Drosophila Gad gene, but both encode proteins of 58 kDa. The derived amino acid sequence reveals a typical pyridoxal phosphate binding site and sequence homology consistent with a glutamate decarboxylase function. The protein includes an amino-terminal polyasparagine sequence, and a beta-pleated sheet region, with regularly spaced glutamine and arginine residues, not found in other decarboxylases. Expression in the adult is limited to the neuropil of the first optic ganglion and to regions of the thoracic musculature that may correspond to the location of motor neuron axons. This is consistent with a glial localization for the transcript. There is no overlap with the reported expression of Drosophila Gad. Although the molecular evidence suggests that this gene encodes a pyridoxal phosphate-dependent decarboxylase, glutamate decarboxylase activity associated with this gene could not be demonstrated, and the in vivo substrate is unknown. It is possible that the protein encoded by this gene is novel, not only in sequence and spatial expression, but also in substrate specificity.

Laser-induced protein-DNA cross-links via psoralen furanside monoadducts

We have developed a technique for cross-linking DNA binding proteins to DNA using psoralen furanside monoadducts as photoaffinity probes and a continuous-wave argon ion laser (366 nm) as a light source. Several DNA binding proteins (T7 RNA polymerase, UvrB, single-stranded DNA binding protein of Escherichia coli, T4 gp32, and RecA of E. coli) are shown to cross-link to single-stranded psoralen monoadducted DNA oligos differing in length and sequence. Increasing fluences of laser light on a fixed ratio of DNA/protein resulted in an increase in the yield of cross-links. Titration experiments were carried out to measure the apparent cross-linking constant (KappXL) for T7 RNA polymerase or UvrB to a monoadducted 24 mer DNA. The estimated values for the apparent cross-linking constant were in the range of (2-3) x 10(-7) M for both T7 RNA polymerase and UvrB. The efficiency of cross-linking was investigated as a function of the length of adducted DNA and also as a fraction of the total noncovalent binding of proteins of psoralenated DNAs. The results showed that in the cases of T7 RNA polymerase and UvrB cross-linking was more efficient with short oligos (8 and 19 mers) as compared to longer oligos (50 mer). A tryptic peptide of T7 RNA polymerase that was conjugated to a psoralen furanside monoadducted 12 mer DNA was isolated by high-performance liquid chromatography. Mass spectrometry and amino acid composition of this peptide revealed that it originated from a region between residues 558 and 608 of the primary structure of T7 RNA polymerase. Two other peptides cross-linked to oligos were also purified. Repeated attempts to perform Edman sequencing of the peptide-DNA conjugates failed. Overall evidence indicates that photo-cross-linking of furanside monoadducts occurred at multiple sites on the proteins. We have shown that T7 RNA polymerase molecules in a ternary complex arrested at the furanside monoadduct can be cross-linked to the DNA templates with laser light. Evidence suggests that the arrested polymerase molecules existed in multiple conformations on the DNA template. This method of transcriptional cross-linking offers a new method for preparing highly stable elongation complexes for further studies.

Active site of (A)BC excinuclease. II. Binding, bending, and catalysis mutants of UvrB reveal a direct role in 3' and an indirect role in 5' incision

UvrB plays a central role in (A)BC excinuclease. To study its role in the incision reactions, conserved His and Asp residues in this subunit were mutagenized. All His and the majority of Asp mutants behaved like wild-type protein in vivo and in vitro. However, three mutants, D337A, D478A, and D510A, either completely or partially abolished UvrB activity. All three mutant proteins associate with UvrA normally but D337A and D510A were unable to bind to DNA specifically. The UvrB-D478A mutant bound to DNA specifically but failed to denature and kink the DNA. However, UvrB-D478A was efficiently loaded onto DNA preincised at the 3' site and promoted near-normal incision by UvrC at the 5' site. We propose that D478 is involved in bending DNA and catalysis of the 3' incision and that the 3' incision precedes the 5' incision. UvrB which is missing the carboxyl-terminal 43 amino acids binds to, and kinks DNA but is unable to make the 3' incision suggesting that it is missing a residue involved in catalysis. This residue was identified to be E639 by site-specific mutagenesis.

Identification of a Drosophila gene encoding a calmodulin-binding protein with homology to the trp phototransduction gene

We have isolated a number of Drosophila cDNAs on the basis of their encoding calmodulin-binding proteins. A full-length cDNA clone corresponding to one of these genes has been cloned and sequenced. Conservation of amino acid sequence and tissue-specific expression are observed between this gene and the transient receptor potential (trp) gene. We propose the name transient receptor potential-like (trpl) to describe this newly isolated gene. The trpl protein contains two possible calmodulin-binding sites, six transmembrane regions, and a sequence homologous to an ankyrin-like repeat. Structurally, the trpl and trp proteins resemble cation channel proteins, particularly the brain isoform of the voltage-sensitive Ca2+ channel. The identification of a protein similar to the trp gene product, yet also able to bind Ca2+/calmodulin, allows for a reinterpretation of the phenotype of the trp mutations and suggests that both genes may encode light-sensitive ion channels.