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J Berriman

Publications and source records attributed to J Berriman.

At least 19 recordsLinked to original sources
PubMed2005

Humidity and aggregate content correction factors for air-coupled ultrasonic evaluation of concrete.

This paper describes the use of non-contact ultrasound for the evaluation of concrete. Micromachined capacitance transducers are used to transmit ultrasonic longitudinal chirp signals through concrete samples using air as the coupling medium, and a pulse compression technique is then employed for measurement of time of flight through the sample. The effect on the ultrasonic wave speed of storing concrete samples, made with the same water/cement ratio, at different humidity levels is investigated. It is shown that there is a correlation between humidity and speed of sound, allowing a correction factor for humidity to be derived. A strong positive linear correlation between aggregate content and speed of sound was then observed; there was no obvious correlation between compressive strength and speed of sound. The results from the non-contact system are compared with that from a contact system, and conclusions drawn concerning coupling of energy into the samples.

Air↗
PubMed2005

Supermarket baker's asthma: how accurate is routine health surveillance?

BACKGROUND: Regular health surveillance is commonly recommended for workers exposed to occupational antigens but little is known about how effective it is in identifying cases. AIMS: To report one large company's surveillance and compare its findings with those of a standard cross-sectional survey in the same workforce. METHODS: A supermarket company with 324 in-store bakeries producing bread from raw ingredients conducted a three-stage health surveillance programme in around 3000 bakery employees. The first stage involved the administration of a simple respiratory questionnaire. If chest symptoms were present a second questionnaire focusing on their work relationship was administered. If positive a blood sample was requested for the measurement of specific IgE to flour and fungal alpha-amylase. The results were compared to an independent cross-sectional survey of employees in 20 of the company's stores. RESULTS: Two hundred and ninety nine (92%) of the company's bakeries took part in surveillance. The overall employee response for the first stage was 77%; a quarter of those with respiratory symptoms reported that they were work related. Seventy four (61%) of those with work related chest symptoms had a measurement of specific IgE to either flour or fungal alpha-amylase, of whom 30 (41%) had a positive result. Surveillance estimated that 1% of bakery employees (1% bakers, 2% managers, 0.6% confectioners) had work related symptoms with specific IgE. This compared with 4% (7.5% bakers, 3.3% managers, 0% confectioners) in the cross-sectional survey (n = 166, 93% response). CONCLUSION: Comparison with a standard cross-sectional survey suggests that routine surveillance can underestimate the workplace burden of disease. The reasons may include technical or resource issues and uncertainties over confidentiality or the perceived consequences of participation. More research needs to be done looking into the design and efficacy of surveillance in occupational asthma.

Asthma↗
PubMed2005

The changing distribution of occupational asthma: a survey of supermarket bakery workers.

In the UK, since the mid 1980s, supermarkets have accounted for an increasing volume of bread production. Occupational asthma among employees who produce bread from raw ingredients in supermarkets has not been previously investigated. A cross-sectional survey was undertaken involving 239 (71%) employees from 20 different supermarket bakeries. The work-related symptoms were investigated by using questionnaires and measuring the radioallergosorbent test serum-specific immunoglobulin (Ig)E to flour and fungal alpha-amylase. A total of 89 employees underwent whole-shift personal measurement of dust exposure. The geometric mean dust exposure for bakers was 1.2 mg x m(-3), which was higher than for other bakery employees. A total of 37 (15%) employees also reported work-related chest symptoms. Serum IgE to flour was present in 24 (11%) employees and to fungal alpha-amylase in nine (4%) employees. The combination of work-related chest symptoms and specific IgE was found in six (9%) bakers, one (4%) manager and two (3%) assistants. One-quarter of all employees, but half of bakers and managers, had previously worked for different, mainly small, bakeries. This population of bakery workers has important levels of sensitisation and work-related respiratory symptoms, despite low levels of dust exposure. Changes in the location and process of bread manufacture have led to a change in the distribution of bakers' asthma in the UK.

Asthma↗
PubMed2002

Amyloid fibers are water-filled nanotubes.

A study of papers on amyloid fibers suggested to us that cylindrical beta-sheets are the only structures consistent with some of the x-ray and electron microscope data. We then found that our own 7-year-old and hitherto enigmatic x-ray diagram of poly-L-glutamine fits a cylindrical sheet of 31 A diameter made of beta-strands with 20 residues per helical turn. Successive turns are linked by hydrogen bonds between both the main chain and side chain amides, and side chains point alternately into and out of the cylinder. Fibers of the exon-1 peptide of huntingtin and of the glutamine- and asparagine-rich region of the yeast prion Sup35 give the same underlying x-ray diagrams, which show that they have the same structure. Electron micrographs show that the 100-A-thick fibers of the Sup35 peptide are ropes made of three protofibrils a little over 30 A thick. They have a measured mass of 1,450 Da/A, compared with 1,426 Da/A for a calculated mass of three protofibrils each with 20 residues per helical turn wound around each other with a helical pitch of 510 A. Published x-ray diagrams and electron micrographs show that fibers of synuclein, the protein that forms the aggregates of Parkinson disease, consist of single cylindrical beta-sheets. Fibers of Alzheimer A beta fragments and variants are probably made of either two or three concentric cylindrical beta-sheets. Our structure of poly-L-glutamine fibers may explain why, in all but one of the neurodegenerative diseases resulting from extension of glutamine repeats, disease occurs when the number of repeats exceeds 37-40. A single helical turn with 20 residues would be unstable, because there is nothing to hold it in place, but two turns with 40 residues are stabilized by the hydrogen bonds between their amides and can act as nuclei for further helical growth. The A beta peptide of Alzheimer's disease contains 42 residues, the best number for nucleating further growth. All these structures are very stable; the best hope for therapies lies in preventing their growth.

Alzheimer Disease↗
PubMed2001

From genetics to pathology: tau and alpha-synuclein assemblies in neurodegenerative diseases.

The most common degenerative diseases of the human brain are characterized by the presence of abnormal filamentous inclusions in affected nerve cells and glial cells. These diseases can be grouped into two classes, based on the identity of the major proteinaceous components of the filamentous assemblies. The filaments are made of either the microtubule-associated protein tau or the protein alpha-synuclein. Importantly, the discovery of mutations in the tau gene in familial forms of frontotemporal dementia and of mutations in the alpha-synuclein gene in familial forms of Parkinson's disease has established that dysfunction of tau protein and alpha-synuclein can cause neurodegeneration.

Amino Acid Sequence↗
PubMed2001

A special courage: dealing with the Paddington rail crash.

Supporting traumatized employees requires special skills and techniques if it is to be effective. Unfortunately, there is little to inform or guide organizations on how this should be achieved. The present controversy over the use of trauma management systems and debriefing has not been helpful in informing organizations on the best way to take care of employees who become traumatized during the course of their work. This paper looks at how Sainsbury's Supermarkets Ltd managed traumatization through the activation of its Violence at Work policy and procedures, and finally presents the results of an evaluation exercise that was undertaken following the Paddington rail crash.

Accidents↗
PubMed2000

Fiber diffraction of synthetic alpha-synuclein filaments shows amyloid-like cross-beta conformation.

Filamentous inclusions made of alpha-synuclein constitute the defining neuropathological characteristic of Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Rare familial cases of Parkinson's disease are associated with mutations A53T and A30P in alpha-synuclein. We report here the assembly properties and secondary structure characteristics of recombinant alpha-synuclein. Carboxy-terminally truncated human alpha-synuclein (1-87) and (1-120) showed the fastest rates of assembly, followed by human A53T alpha-synuclein, and rat and zebra finch alpha-synuclein. Wild-type human alpha-synuclein and the A30P mutant showed slower rates of assembly. Upon shaking, filaments formed within 48 h at 37 degrees C. The related proteins beta- and gamma-synuclein only assembled after several weeks of incubation. Synthetic human alpha-synuclein filaments were decorated by an antibody directed against the carboxy-terminal 10 amino acids of alpha-synuclein, as were filaments extracted from dementia with Lewy bodies and multiple system atrophy brains. Circular dichroism spectroscopy indicated that alpha-synuclein undergoes a conformational change from random coil to beta-sheet structure during assembly. X-ray diffraction and electron diffraction of the alpha-synuclein assemblies showed a cross-beta conformation characteristic of amyloid.

Amyloid↗
PubMed1998

Evaluation of charging on macromolecules in electron cryomicroscopy.

We describe procedures to assess charging of biological specimens under electron irradiation in an electron cryomicroscope. Charging can be observed by an expansion of the illuminating beam, blurring of electron diffraction patterns and by beam "footprints" on the specimen. Discharging can also be seen in the defocused electron diffraction mode. We investigated the influence of a variety of factors on the magnitude and visibility of charging. A reduction of charging is noticed when part of the adjacent carbon film is included in the irradiated specimen area.

Catalase↗
PubMed1994

Analysis of transient structures by cryo-microscopy combined with rapid mixing of spray droplets.

A simple method to determine transient conformations of biological molecules is described. The two reactants (e.g. protein complex and ligand) are mixed rapidly by the coalescence of spray droplets containing one component, with a thin, grid-supported aqueous film containing the other. The transient state is then trapped by rapid freezing, and investigated later by cryo-microscopy. Images of conformations associated with reaction times of 1-100 ms can be achieved by adjusting the delay between the droplet impact and freezing. The droplets (typically 1 micron in diameter) are propelled onto the grid by an atomizer spray. It is shown that the droplets impinging on the liquid film spread rapidly over its surface under the influence of surface tension, and only weakly disturb the underlying film, partially displacing its contents away from the point of impact. Experiments with sprayed salt solutions, using vesicles derived from erythrocytes as micro-osmometers, indicate that rapid mixing occurs both through the film and laterally, by diffusion. The spraying process does not produce any detectable concentration changes due to drying in either the droplets or the film, and the method is applicable to high-resolution imaging.

Acetylcholine↗
PubMed1994

Herpes simplex virus L particles contain spherical membrane-enclosed inclusion vesicles.

The fine structure of light (L) particles of herpes simplex virus type 1 was examined by cryo-electron microscopy and compared to that of virions. The L particles appeared to be spherical entities with significant variation in size, on average smaller in diameter than virions (140 nm compared to 180 nm). The technique confirmed that L particles are composed of an outer envelope, i.e. a bilaminar membrane with protruding glycoprotein spikes, and a uniformly granular tegument, but lack any nucleocapsid. In addition it revealed the presence of one or occasionally more spherical objects, termed inclusion vesicles (IVs), embedded in the tegument of a large proportion of L particles but not observed in virions, suggesting that presence of IVs is unique to the L particles. The IVs vary in size and appear to be composed of a bilaminar membrane without surface projections and filled with material of relatively low electron density, suggesting that the composition of IVs is distinct from that of the envelope and tegument of the L particles.

Capsid↗
PubMed1992

In vitro and in vivo mutagenicity studies on sporidesmin, the toxin associated with facial eczema in ruminants.

Sporidesmin, a fungal toxin with widespread distribution within New Zealand, is thought to exert toxic effects through oxidative damage. The purified chemical was tested for its ability to cause point mutations in four strains of Salmonella typhimurium (TA98, TA100, TA102 and TA1537), in the presence and absence of exogenous metabolic activation. Although toxic effects were seen at concentrations exceeding 400 mu gl/plate, there were no significant increases in revertant colonies. In strain TA102, these results were not modified by the presence of glutathione. In AA8 Chinese hamster cells, sporidesmin acted as a potent clastogen, causing chromosomal breaks at concentrations as low as 3 ng/ml, where there was very little reduction in cell viability. Effects were primarily at the chromatid level, but some chromosomal events were also seen. Following low doses, the most common events were chromatid deletions and induction of double minute chromosomes. Interchange events occurred at concentrations of 10 ng/ml and above. The most common of these events was an incomplete chromatid interchange, although some examples of complete chromatid and chromosomal interchange were seen. These in vitro experiments were subsequently extended to an in vivo study of sporidesmin-induced lymphocytic micronuclei (MN) in sheep. In a double blind experiment, 5 sheep were treated with a single high dose of sporidesmin. Blood samples were taken from these, and from 5 untreated sheep, at various intervals before and after treatment. Peripheral blood lymphocytes cultures were harvested and scored for MN in cytokinesis-blocked cells, as a measure of clastogenic activity of sporidesmin in vivo. Following decoding, statistical analysis of the data revealed no significant differences between the MN levels in peripheral blood lymphocytes of sporidesmin-treated and untreated sheep. Although the possibility still exists that clastogenic effects could occur in other species, the data indicate that sporidesmin is not a clastogen in sheep, even though this species is highly susceptible to the toxic effects of sporidesmin.

Animals↗
PubMed1992

Rotavirus VP6 modified for expression on the plasma membrane forms arrays and exhibits enhanced immunogenicity.

The major inner capsid protein of rotavirus is VP6, a 42-kDa polypeptide that forms the icosahedral surface of the rotavirus single-shelled particle. A chimeric form of VP6 (VP6sc) was constructed containing an upstream leader sequence derived from the influenza virus hemagglutinin and a downstream membrane-spanning (anchor) domain from a mouse immunoglobulin gene. When VP6sc was expressed in cells using a recombinant vaccinia virus, the protein was transported, glycosylated, and anchored in the plasma membrane as a trimer with the major domains of the protein orientated externally. Immunofluorescence and immunolabeling with colloidal gold indicated that VP6sc also localized in patches on the cell surface; electron microscopy revealed that the protein assembled into two-dimensional arrays which exhibited the same periodicity as the paracrystalline arrays formed by purified (viral) VP6. Mice inoculated with a recombinant vaccinia virus that expressed VP6sc produced rotavirus-specific antibodies at a titer 10 times higher than that achieved when wild-type, intracellular VP6 was delivered in the same way. Presentation at the cell surface therefore may represent a general method for enhancing the immunogenicity of rotavirus proteins.

Animals↗
PubMed1990

Direct-acting mutagenic properties of some hair dyes used in New Zealand.

Mutagenicity or carcinogenicity data are not publicly available on many hair dyes or dye components commonly used within New Zealand. Representative mid- to dark-warm brown hair dyes of 12 brands supplying more than 1% of the New Zealand market were tested for direct-acting mutagenicity using the bacterial 'Ames' test. Despite recent scientific advances in the development of non-mutagenic dyes, 23 of the 40 products tested gave positive results in one or both of the tester strains used. There appeared to be differences between distributors in the proportion of their hair dyes which were mutagenic. In the case of 6 out of 10 of the above dyes which had tested positive, in vitro mutagenicity or toxicity was enhanced in the presence of verapamil, suggesting that risks from hair-dye exposure may change in the case of persons using this or similar drugs. It is recognised that there are uncertainties regarding human risks from dyes which are shown to be mutagenic in in vitro tests. However, from the above results, it seems possible to produce non-mutagenic hair dyes in this color range; and in the interests of public reassurance, it may be prudent to require that such dyes be used.

Drug Synergism↗
PubMed1990

Molecular portrait of lens gap junction protein MP70.

A 70-kDa membrane protein (MP70) is a component of the lens fiber gap junctions. Its membrane topology and its N-terminal sequence are similar to those of the connexin family of proteins. Some features of MP70 containing fiber gap junctions are, however, distinct from gap junctions in other mammalian tissues: (i) Lens connexons form crystalline arrays only after cleavage of junctional proteins in vitro. These hexagonal arrays have a periodicity of 13.6 nm which is significantly larger than the 8- 9-nm spacing of liver and heart gap junctions. (ii) Lens fiber gap junctions dissociate in low concentrations of nonionic detergent and this provides an avenue to purify MP70 directly from a membrane mixture. Isolated MP70 in the form of 17 S structures has an appearance consistent with connexon pairs. (iii) The C-terminal half of MP70 is cleaved in situ by a lens endogenous calcium-dependent protease. The processed from MP38 remains in the membrane and is abundant in the central region of the lens. A testable hypothesis for MP70 function is presented.

Connexins↗
PubMed1986

Ultrastructure of native lipoprotein from Escherichia coli envelopes.

The free form of the major lipoprotein from Escherichia coli cells envelopes has been purified to homogeneity by gentle extraction procedures and conventional chromatographic separations in a non-ionic detergent. The morphology of paracrystals obtained from homogeneous protein was investigated by low-dose electron microscopy. Electron diffraction of the paracrystals was consistent with alpha-helices arranged perpendicularly to the main cross-band with a periodicity of 20 nm.

Bacterial Outer Membrane Proteins↗
PubMed1986

Methods for specimen thickness determination in electron microscopy. II. Changes in thickness with dose.

The electron diffraction patterns of tilted thin crystals were used to determine the unit cell size in the direction normal to the supporting film. The method revealed a considerable dose-dependent thinning or shrinkage. Using a variety of specimens and stains, we found that this amounted to a 50% reduction in volume and could be attributable to two causes. Firstly, the specimen is held to the supporting film so that volume changes can only occur through changes in thickness. Secondly, the decrease in volume is associated with a dose-induced mass loss which is greatly suppressed at liquid nitrogen temperatures.

Crystallography↗
PubMed1984

Methods for specimen thickness determination in electron microscopy.

A new method is described for specimen thickness determination in transmission electron microscopy. This is carried out by marking specimens with gold particles and analysing the images of a tilt series by computer. The method makes it possible to distinguish populations of particles on different planes and calculate the distance between the planes with statistical variation. We have applied it to carbon films as test objects and compared the results with those obtained by transverse sectioning, STEM mass measurement, optical density and frequency change of a quartz crystal oscillator. We have then used the method for thickness measurement of multilayered protein crystals and thin sectioned cells.

Animals↗