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Biomedical subjects

S A Walker

Publications and source records attributed to S A Walker.

16 recordsLinked to original sources
PubMed1992

Cloning, expression, and nucleotide sequence of genes involved in production of pediocin PA-1, and bacteriocin from Pediococcus acidilactici PAC1.0.

The production of pediocin PA-1, a small heat-stable bacteriocin, is associated with the presence of the 9.4-kbp plasmid pSRQ11 in Pediococcus acidilactici PAC1.0. It was shown by subcloning of pSRQ11 in Escherichia coli cloning vectors that pediocin PA-1 is produced and, most probably, secreted by E. coli cells. Deletion analysis showed that a 5.6-kbp SalI-EcoRI fragment derived from pSRQ11 is required for pediocin PA-1 production. Nucleotide sequence analysis of this 5.6-kbp fragment indicated the presence of four clustered open reading frames (pedA, pedB, pedC, and pedD). The pedA gene encodes a 62-amino-acid precursor of pediocin PA-1, as the predicted amino acid residues 19 to 62 correspond entirely to the amino acid sequence of the purified pediocin PA-1. Introduction of a mutation in pedA resulted in a complete loss of pediocin production. The pedB and pedC genes, encoding proteins of 112 and 174 amino acid residues, respectively, are located directly downstream of the pediocin structural gene. Functions could not be assigned to their gene products; mutation analysis showed that the PedB protein is not involved in pediocin PA-1 production. The mutation analysis further revealed that the fourth gene, pedD, specifying a relatively large protein of 724 amino acids, is required for pediocin PA-1 production in E. coli. The predicted pedD protein shows strong similarities to several ATP-dependent transport proteins, including the E. coli hemolysin secretion protein HlyB and the ComA protein, which is required for competence induction for genetic transformation in Streptococcus pneumoniae.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Taurine uptake in chicken leukocytes and erythrocytes.

1. The intracellular taurine concentration and rate of taurine uptake of chicken erythrocytes and two leukocyte populations were determined from one to six weeks of age. 2. Plasma taurine concentrations increased significantly from the time of hatching to week 2 and remained constant thereafter. 3. Intracellular taurine concentrations in both leukocyte populations increased significantly with age without any significant change in the erythrocytes. 4. Taurine uptake rate for erythrocytes was significantly higher at weeks 1-3 while both leukocyte populations showed no significant change during the six week period studied.

Animals↗
PubMed1986

Total and allergen-specific IgE in relation to allergic response pattern following bone marrow transplantation.

Total and allergen-specific serum IgE were measured in relation to allergic response pattern before and after bone marrow transplant (BMT) in seven sibling donor/recipient pairs. Two non-atopic recipients developed persistently raised total serum IgE levels but no apparent allergic response after BMT from non-atopic donors; three non-atopic recipients showed raised total serum IgE after BMT, with allergen-specific IgE to the same allergens as their respective atopic donors. A penicillin-tolerant recipient showed clinical sensitivity and specific IgE to penicillin after BMT from a penicillin-sensitive donor, but with this case both donor and recipient showed raised serum IgE levels. One atopic recipient showed decreased total IgE after BMT from a mildly atopic donor. These allergic response patterns could occur as a result of repopulation in the recipient with IgE-specific T lymphocytes having similar regulatory influences as in the donor. The pattern of acquired responses would also be consistent with reconstitution by primed B lymphocytes of donor origin.

Adolescent↗
PubMed1985

The action spectrum for benzanthrone photosensitization of mouse macrophages.

An in vitro method for determination of the phototoxic action spectrum of benzanthrone was established using a cover slip-test tube culture system with mouse peritoneal macrophages. The action spectrum peaked between 380 and 400 nm with abrupt fall-off to either side. These findings correlate closely with both the absorption spectrum of benzanthrone and the clinical action spectrum of phototoxicity in humans.

Animals↗
PubMed1984

Increased serum IgE concentrations during infection and graft versus host disease after bone marrow transplantation.

Serum IgE concentrations estimated in 25 bone marrow transplant recipients during episodes of infection or graft versus host disease, or both, were raised not only in some patients with acute graft versus host disease but also in many patients with infection. Raised values were not seen in chronic graft versus host disease. The routine estimation of serum IgE in bone marrow transplant recipients had minimal value because of the lack of specificity of the IgE response.

Acute Disease↗
PubMed1984

Value of serum C-reactive protein measurement in the management of bone marrow transplant recipients. Part I: Early transplant period.

Serum C-reactive protein concentrations were measured serially during the early transplant period in 68 bone marrow recipients transplanted for leukaemia (34), chronic granulocytic leukaemia (2), severe aplastic anaemia (6), and various inborn errors of metabolism (26). There were 116 clearly documented episodes of infection or acute graft versus host disease or both. Serum C-reactive protein concentrations in patients with viral (11) or fungal infection (6) were normal or only slightly raised. In 32 patients with isolated acute graft versus host disease, only three (10%) showed serum C-reactive protein concentrations above 40 mg/l. Values greater than 40 mg/l were strongly suggestive of bacterial infections and values above 100 mg/l were seen only in patients (43) with bacterial infections with or without acute graft versus host disease. These findings suggest that serum C-reactive protein concentrations are valuable both for diagnosis and monitoring of such infections.

Acute Disease↗
PubMed1984

Value of serum C-reactive protein measurement in the management of bone marrow transplant recipients. Part II: Late post-transplant period.

Seventeen bone marrow recipients transplanted for acute leukaemia (8), chronic leukaemia (1), severe aplastic anaemia (3), and various inborn errors of metabolism (5) had 22 episodes of documented infection in the late (greater than 3 months) post-transplant period. Serum C-reactive protein concentrations were considerably increased in patients with bacterial infections, but not in those with viral or fungal infections. Serum C-reactive protein values were normal in 20 patients transplanted for acute leukaemia (12), chronic leukaemia (1), severe aplastic anaemia (2), and various inborn errors of metabolism (5) who had active chronic graft versus host disease but no evidence of infection. These findings indicate that serum C-reactive protein concentrations are useful in the diagnosis and monitoring of bacterial infections even in the presence of chronic graft versus host disease.

Bacterial Infections↗
PubMed1984

The communication status of older people: differentiation and rehabilitation.

The communication integrity of the older individual is subject to many influences. Understanding and management of the elderly communication-handicapped can prove difficult because of the problems of differential diagnosis. The role of the speech therapist is acknowledged in acute geriatric rehabilitation but is not immediately associated with psychogeriatric care. The laws of language deterioration appear to apply irrespective of aetiology. Standard linguistic rehabilitation techniques may be equally applicable in both geriatric and psychogeriatric care.

Aged↗
PubMed1977

Who needs speech therapy?

Assessment of communication by a patient with a speech disorder by clinicians is often dependent on whether the patient makes an appropriate response to an instruction. The speech therapist concerned with language usage and the over-all ability to communicate has developed skills and investigational techniques to identify subgroups within the broad categories of speech pathology appreciated by the clinicians. This prospective study of 100 patients with neurological disease referred for speech therapy, examined in detail in good working conditions and with ample therapy time, is intended to clarify for the clinician a method of assessment, and to illustrate the value of therapy, and establish a prognosis for the variety of speech and language disorders encountered.

Aged↗