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Biomedical subjects

D H Watson

Publications and source records attributed to D H Watson.

At least 19 recordsLinked to original sources
PubMed1993

Cervical headache: an investigation of natural head posture and upper cervical flexor muscle performance.

In this study, 60 female subjects, aged between 25 and 40 years, were divided into two equal groups on the basis of absence or presence of headache. A passive accessory intervertebral mobility (PAIVM) examination was performed to confirm an upper cervical articular cause of the subjects' headache and a questionnaire was used to establish a profile of the headache population. Measurements of cranio-cervical posture and isometric strength and endurance of the upper cervical flexor muscles were compared between the two groups of subjects. The headache group was found to be significantly different from the non-headache group in respect to forward head posture (FHP) (t = -5.98, p < 0.00005), less isometric strength (t = 3.43, p < 0.001) and less endurance (t = 8.71, p < 0.0005) of the upper cervical flexors. A statistically significant relationship was also established between natural head posture and isometric endurance of the upper cervical flexor musculature which demonstrated that FHP corresponded with a low endurance capacity (chi 2 = 13.2; p < 0.01). The outcome of this study highlights the need to screen for cervical etiology in patients who are suspected of suffering from common migraine.

Adult↗
PubMed1985

Toxic fungal metabolites in food.

About 100 fungal metabolites may cause cancer, embryological defects, or other histopathological effects in mammals. They are produced by a wide variety of fungi. Few of these metabolites have significant acute toxicity. With the exception of aflatoxin B1 and sterigmatocystin, there is no conclusive evidence that any of them is carcinogenic. However, several of the compounds are mutagenic. Cytochalasin D and T-2 toxin are probably teratogenic. A wide variety of other histopathological effects have been shown. Liver damage has been most frequently reported. In almost all cases the molecular bases of these effects have not been extensively investigated. Although much is known about the routes by which some of the compounds are synthesized in vivo, nothing is known about control at the molecular level of these biosynthetic routes. Little is known about the biological degradation of these compounds or about the levels and incidences of them in food and animal feed. Future work in all these areas will depend on the further development of sensitive assay methods that are applicable to their measurement in food, in animal feed, and in animal tissues and body fluids and on the application of these methods to define exposure to these compounds in the diet.

Animal Feed↗
PubMed1985

Purification of herpes simplex virus glycoproteins B and C using monoclonal antibodies and their ability to protect mice against lethal challenge.

Monoclonal antibodies which react with herpes simplex virus type 1 (HSV-1) glycoproteins, but do not neutralize infectivity, were prepared. The protein to which each monoclonal antibody was directed was determined by various techniques including their reaction with polypeptides from glycoprotein-deficient mutants after protein blotting, and also tests using passive haemagglutination. Monoclonal antibodies A7 and alpha C3 were directed against a type-specific determinant on gC and a type-common determinant on gB respectively. In addition, A7 reacted only with the HFEM strain of HSV-1 and did not react with any of the 20 low-passage human isolates also tested. The monoclonal antibodies were used in immunoadsorption chromatography to purify individual glycoproteins from detergent extracts of HSV-1-infected cells. The ability of the monoclonal antibodies or purified glycoproteins to protect mice against a lethal encephalitis induced by intracerebral inoculation of HSV-1 was investigated. Passive immunization was not very effective; however, purified gC or a mixture of gB and its precursor pgB induced good levels of neutralizing antibody which persisted for at least 9 weeks and mice survived virus challenge.

Animals↗
PubMed1983

A note on inhibition test and electrophoretic detection limits of antibiotics used in British animal husbandry.

A four plate microbiological inhibition test (the FPT) and a bioelectrophoretic method were evaluated for their ability to detect a range of antibiotic agents, which may be present as residues in animal tissues following their therapeutic use in animal husbandry. Both methods exhibited a wide range of sensitivities and several of the tested antibiotics could not be detected by either method. The pattern of responses across the bacterial plates in the FPT could not be used to identify agents and the bioelectrophoretic inhibition zone diameters were generally too large to allow the use of Rs values for identification. The Bacillus subtilis pH 7.2 plate with trimethoprim added was as effective as the four bacterial plates used in the FPT in antibiotic detection.

Animals↗
PubMed1980

Precolicin E1, the major gene product of plasmid-ColE1 deoxyribonucleic acid in vitro.

Coupled transcription and translation of plasmid-ColE1 DNA in vitro under optimized conditions gave one major product. This has an apparent weight of 71 000, the same N-terminal sequence as colicin E1 and was not digested by deoxyribonuclease or ribonuclease. It differed from colicin E1 in its C-terminal residue and amino acid composition. It had lower specific activities in cell killing and in the fluorescence-enhancement in vitro assay of Phillips & Cramer [(1973) Biochemistry 12, 1170--1176] than did colicin E1, but both proteins bound in equimolar amounts to colicin-sensitive and colicin-resistant cells. The product of plasmid-ColE1-DNA-directed protein synthesis was converted into a protein indistinguishable in structure and activity from colicin E1 by incubation in the reaction mixture, after deoxyribonuclease and ribonuclease treatment, for a further 20 h at 37 degrees C. A protein with similar properties to the 71 000-dalton product in vitro was identified in extracts of a ColE1+ colicin-tolerant mutant of Escherichia coli K12. It is concluded that this protein probably represents a pre-form of colicin E1 which may be involved in colicin-E1 secretion or cellular colicin-E1 immunity in colicin-E-producing cells, or both of these processes.

Amino Acids↗
PubMed1980

Glycoproteins with type common and type specific antigenic sites excreted from cells infected with herpes simplex virus types 1 and 2.

Agar immunodiffusion tests demonstrated that BHK 21 cells infected with either HSV I or HSV 2 release only a few HSV-specified antigens into the extracellular fluid (infected cell released polypeptides-ICRP). Neutralization blocking experiments showed that the majority of antigens/(including the Band II common antigen) involved as target sites in antibody-mediated virus neutralization are present in the ICRP of both HSV I and HSV 2.SDS-PAGE identified six regions of virus-specified proteins in the ICRP from both HSV I- and HSV 2-infected BHK cells. All these specifically released proteins are glycosylated, although to varying degrees. The SDS-PAGE profiles of HSV I and HSV 2 ICRP are different but do show some similarities, the most notable being a highly glycosylated protein with an estimated mol. wt. of 50,000 to 54,000 in HSV I ICRP and 52,000 to 56,000 in HSV 2 ICRP. Immune precipitation demonstrated that these two proteins contain the Band II antigenic site. Similar studies showed that the major type I specific antigenic site, which is involved as a target site in the neutralization of virus infectivity, is located in the highest mol. wt. glycoprotein region of HSV I ICRP and has a similar mobility to the VP7/8 region of purified enveloped virus.

Animals↗
PubMed1980

Cellular distribution of beta-lactamase RP4 is mediated by an outer membrane protease.

RP4 beta-lactamase extracted from the outer membrane of wild-type Escherichia coli can be resolved into several interconvertible forms that differ in their stabilities, substrate profiles and apparent molecular weights. beta-Lactamase isolated from outer membrane of strains which are lacking a protease that is involved in the cleavage of colicins differs from the beta-lactamase of parental cells in substrate profile, apparent molecular weight and the ability to interconvert. The cellular distribution of beta-lactamase also differs between wild-type and protease-deficient mutants. Both strains have equivalent amounts of beta-lactamase in their outer membranes, however the parental strain also has considerable beta-lactamase in the cytoplasmic membrane while the mutant does not. In addition the mutant contains only 30% of the parental level of enzyme in the periplasm. It is proposed that the reduced level of periplasmic enzyme is the result of a defect in processing of membrane-associated beta-lactamase. This conclusion is supported by the observation that the beta-lactamase isolated from the mutant can be converted to forms resembling those found in the parent by incubation with extracts or outer membrane isolated from the parent.

Cell Membrane↗
PubMed1980

Recombination and linkage between structural and regulatory genes of herpes simplex virus type 1: study of the functional organization of the genome.

Phenotypic and genetic properties of 12 markers in structural and regulatory functions of herpes simplex virus type 1 were characterized, and their recombination and segregation behavior was investigated and interpreted with reference to available information on their physical locations. The markers were: (i) ts markers in a structural glycoprotein (tsB5) and in alpha (immediate early; tsLB2, tsc75) or beta (early, delayed early; tsB1) functions with regulatory effects; together with (ii) plaque morphology (syn), phosphonoacetate resistance (Pr), and thymidine kinase (TK) phenotypes; and (iii) electrophoretically distinct variants of glycosylated (glycoprotein C, gpC; ICP10) and non-glycosylated [VP(13-14), VP23] structural and nonstructural [ICP(47-48)] polypeptides. Mean two-factor recombination frequencies ranged from 2% (for noncomplementing mutants tsLB2 and tsc75) to 35 to 40% (for unlinked markers) and were influenced by the relative contributions of parental viruses to the mixed infection. Even with control of this variable, standard deviations of mean measures of recombination frequency ranged from a minimum of 14% (with n greater than or equal to 10) to 65% (with n = 3) of mean values; no recombination frequencies higher than 55% were observed. Differences in mean two-factor recombination frequencies between a small number of loosely linked markers were, therefore, not reliable measures of real differences in linkage. Measurements of the segregation of unselected markers among recombinant progeny were, therefore, used as measures of linkage. These experiments (i) established a linkage group for markers in the long unique region of the genome additional to, but consistent with, existing physical data, i.e., TK-syn-tsB5-(tsB1.Pr)-[gpC.VP(13-14)]; (II) identified markers, e.g., ICP(47-48), linked to regulatory mutations (tsLB2, tsc75) in redundant DNA sequences; and (iii) used the segregation of these regulatory mutations and linked markers among unselected progeny to demonstrate the linkage groups: Pr-syn-TK-tsc75-ICP(47-48), [VP(13-14).gpC]-Pr-syn-TK, and TK-tsc75-[VP(13-14).gpC]. These results were most simply explained if bi- or intermolecular recombination occurred between circular molecules or molecules catenated "head-to-tail" and were incompatible with intermolecular recombination as the mechanism of isomerization of herpes simplex virus DNA.

Genes↗
PubMed1979

Protein purification using immobilised triazine dyes.

This review attempts to identify proteins which selectively interact with immobilised triazine dyes such as Cibacron blue F3GA and Procion red HE 3B. Different support matrices are compared by examining the capacities of these dyes for proteins. Various approaches to the immobilisation of triazine dyes are considered together with the use of spacers. Some theories of the mechanism of protein retardation by immobilised dyes are discussed. A number of methods are suggested for the measurement of dye concentrations and for the modification of the binding of proteins to dye columns. The variety of elution methods is compared with a view to optimizing purifications. The scope of applications is reviewed as well as the choice of dye. Some advantages of triazine dyes over other affinity ligands are given. It is concluded that although no satisfactory mechanism for the binding of triazine dyes to proteins has yet been proposed, these dyes possess considerable potential for protein purification, particularly when applied on the large scale.

Animals↗