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Biomedical subjects

C Walker

Publications and source records attributed to C Walker.

At least 253 records · Page 14Linked to original sources
PubMed1991

Analysis of ras DNA sequences in rat renal cell carcinoma.

The DNA sequences for Ha-, Ki-, and N-ras were determined in six cell lines derived from independent rat hereditary renal cell carcinomas (RCC). Genomic regions encompassing codons 12, 13, and 61 of Ha-ras, Ki-ras, and N-ras, and codon 117 of Ha-ras were PCR amplified and directly sequenced. The DNA sequences of Ha-ras and Ki-ras were normal in all lines tested, as were the codon 12 and 61 sequences of N-ras. However, DNA sequence variations that could code for amino acid substitutions were observed in codons 13, 14, and 18 of N-ras in all the lines. The codon 13 Gly----Val alteration observed was consistent with activating N-ras mutations previously reported. When normal kidney DNA from rats with the hereditary tumor syndrome was sequenced, the same N-ras sequence variations observed in the tumor lines were found. DNA from outbred Long-Evans and inbred Fischer rats also had the altered N-ras sequences. The variant N-ras sequence was not observed in PCR-amplified N-ras cDNA from the RCC lines. Thus, tumor-associated activation of ras oncogene appears to be an infrequent event in spontaneous rat RCC. In addition, these data indicate that rats contain an N-ras DNA polymorphism that appears to be a species-specific anomaly.

Animals↗
PubMed1991

Activated T cells and eosinophilia in bronchoalveolar lavages from subjects with asthma correlated with disease severity.

Activated T-lymphocytes may regulate the eosinophilic inflammation of bronchial asthma. In the present study, we investigated T cell activation and eosinophilia in blood and bronchoalveolar lavage (BAL) in 17 patients with asthma not receiving steroid treatment. Compared to normal individuals, BAL from patients with asthma contained significantly increased numbers of both lymphocytes and eosinophils (EOSs). The lymphocytosis consisted of increased numbers of both CD4+ and CD8+ T cells, and these T cell populations expressed elevated levels of T cell activation markers (interleukin-2 receptor [CD25], HLA-DR, and very late activation antigen 1). Close correlation was found between numbers of BAL CD4+ IL-2R+ T cells and numbers of EOSs. Moreover, the numbers of activated T cells and EOSs were related to the severity of asthma as measured by impairment of FEV1 and increased methacholine bronchial responsiveness. We demonstrate in both blood and BAL a close correlation between T cell activation, eosinophilia, and severity of asthma, suggesting that recruitment and activation of lymphocytes and EOSs are fundamental to the pathogenesis of bronchial asthma.

Adult↗
PubMed1991

Sputum eosinophils from asthmatics express ICAM-1 and HLA-DR.

Sputum from symptomatic asthmatics is a rich source of eosinophils from the respiratory tract. Following liquefaction of sputum with dithioerythritol (DTE), a cell suspension for indirect double immunofluorescence with flow cytometry was obtained. Eosinophils were identified using anti-CD9 fluorescein conjugate, and particular surface markers measured with the relevant mouse MoAb followed by goat anti-mouse immunoglobulin phycoerythrin conjugate. Blood and sputum eosinophil surface markers were determined in parallel from asthmatics not receiving steroid therapy. Sputum eosinophils were found to have considerably elevated levels of CD11b, a reflection of eosinophil activation. Sputum but not blood eosinophils were found to express ICAM-1 (nine out of 11 cases) and HLA-DR (eight out of 11 cases). Furthermore, following culture of normal blood eosinophils with pooled T cell supernatants, ICAM-1 and HLA-DR could be induced in vitro. The induction of eosinophil adhesion molecules such as ICAM-1 and HLA-DR may influence eosinophil localization and function in asthma.

Antigens, CD↗
PubMed1991

Atypical case of Pott's disease.

An unusual case of Pott's Disease in an adult, Australian born, caucasian male is reported. The typical and atypical radiological features of spinal tuberculosis are reviewed.

Aged↗
PubMed1991

Epidemiological characteristics of Legionella infection in South Australia: implications for disease control.

About one third of adults surveyed in South Australia have shown evidence of past silent infection with Legionella pneumophila serogroup 1. However, the annual notification rate for symptomatic disease is only about 0.5 per 100,000 residents in non-epidemic years. The male to female ratio is 2.5 to one and approximately 50% of the cases are at least 60 years of age. Cases have presented more in summer and in the metropolitan areas. Twenty cases of Legionnaires' disease occurred during the summer of 1985-86. A cooling tower was held to be the principal source with aerosols being dispersed up to three kilometers away during an atmospheric thermal inversion. A subsequent outbreak of 22 L. longbeachae serogroup 1 infections had no marked geographic clustering. The outbreak commenced in spring and cases were distinguished as active gardeners. L. longbeachae was found in garden soil and it is hypothesised that this soil inhabitant can become aerosolised and inhaled during gardening. The potential for primary prevention of Legionnaires' disease is discussed in relation to water-handling equipment and the need for early precautionary treatment of all community-acquired pneumonia as suspect Legionnaires' disease is emphasised.

Case-Control Studies↗
PubMed1991

The effect of 'standard drink' labelling on the ability of drinkers to pour a 'standard drink'.

Australia's National Health Policy on Alcohol has recommended that beverage containers be labelled so that alcohol content is 'readily understandable by the public'. Health promotion to increase the responsible use of alcohol now relies extensively on the concept of a standard drink--usually defined as 10 g of ethyl alcohol. Numerous difficulties confront a drinker who wishes to apply the standard drink system to monitor alcohol intake. This report describes a series of experimental tests of the proposal that these difficulties are minimised if alcohol containers have their alcohol content indicated in terms of standard drinks in addition to the usual percentage alcohol by volume method. Subjects were drinkers recruited from a Perth shopping mall and were tested only on beverage types they had consumed within the previous week. They were required to pour what they judged to be a single standard drink from a 750 ml bottle of either wine or beer. Beer drinkers achieved greater accuracy in this task when the bottles had standard drink labels, even when the glass size and beverage strength were varied. Wine drinkers had equal difficulty with this task whether standard drink or percentage labels were used. The addition of a 'ladder' up the side of a wine bottle with graduations in standard drinks would be necessary for wine drinkers to achieve a high level of accuracy. We conclude that labelling drink containers with their alcohol content in terms of standard drinks would better equip all drinkers to follow the advice of health educators.

Adolescent↗
PubMed1991

Characterization of a beta-lactamase found in Eikenella corrodens.

Eleven strains of Eikenella corrodens with beta-lactamase activity were isolated from a patient with refractory periodontitis who had previously been treated with penicillin antibiotics. These strains were relatively resistant to benzylpenicillin, amoxicillin, and ampicillin (MICs, greater than or equal to 64 micrograms/ml); susceptible to amoxicillin-clavulanate (2:1) (MICs, less than or equal to 4 micrograms/ml); and moderately susceptible to cephalothin and cephaloridine (MICs, 0.12 to 16 micrograms/ml). The addition of 1 microgram of potassium clavulanate, a beta-lactamase inhibitor, per ml resulted in a significant increase in the susceptibilities of these strains to penicillins but not to cephalosporins. Potassium clavulanate had no effect on non-beta-lactamase-producing strains. Enzyme production was constitutive since activity was not increased when cells were cultivated in the presence of benzylpenicillin. Enzyme activity was strongly inhibited by potassium clavulanate, sulbactam, and iodine; weakly inhibited by cloxacillin, imipenem, and moxalactam; but not inhibited by aztreonam, EDTA, or p-chloromercuribenzoate. By gel infiltration, the enzyme had an estimated molecular mass of 29 kDa. Isoelectric focusing of the partially purified enzyme gave a major beta-lactamase band at pH 5.50 and a minor band at pH 5.60. Plasmids were not detected in any of the 11 beta-lactamase-positive strains. This enzyme is considered to belong to class 2a of the Bush classification scheme.

Eikenella corrodens↗
PubMed1991

Survival of Legionella pneumophila in the cold-water ciliate Tetrahymena vorax.

The processing of phagosomes containing Legionella pneumophila and Escherichia coli were compared in Tetrahymena vorax, a hymenostome ciliated protozoan that prefers lower temperatures. L. pneumophila did not multiply in the ciliate when incubated at 20 to 22 degrees C, but vacuoles containing L. pneumophila were retained in the cells for a substantially longer time than vacuoles with E. coli. Electron micrographs showed no evidence of degradation of L. pneumophila cells through 12 h, while E. coli cells in the process of being digested were observed in vacuoles 75 min after the addition of the bacterium. T. vorax ingested L. pneumophila normally, but by 10 to 15 min, the vacuolar membrane appeared denser than that surrounding nascent or newly formed phagosomes. In older vacuoles, electron-dense particles lined portions of the membrane. Acidification of the phagosomes indicated by the accumulation of neutral red was similar in T. vorax containing L. pneumophila or E. coli. This ciliate could provide a model for the analysis of virulence-associated intracellular events independent of the replication of L. pneumophila.

Animals↗
PubMed1991

Clinical experience with the Palmaz-Schatz coronary stent. Initial results of a multicenter study.

Stenting of native coronary arteries with a balloon-expandable stent was attempted in 226 patients after elective angioplasty. Delivery of the device was successful in 213 (94%) of the patients. Of these, 39 received aspirin and dipyridamole only (group 1) and 174 received aspirin, dipyridamole, and warfarin for 1-3 months (group 2). There was no abrupt closure (less than or equal to 1 day) or perioperative death in either group. In-hospital or perioperative complications in group 1 compared with group 2 were as follows: subacute closure (1-14 days), seven (18%) patients versus one (0.6%) patient, respectively, p less than 0.0001; myocardial infarction, five (13%) patients versus one (0.6%) patient, respectively; condition requiring urgent bypass surgery, one (2.5%) patient versus no patients, respectively. Thus, the incidence of major complications such as death, myocardial infarction, or a condition requiring urgent bypass surgery was 15% in group 1 and 0.6% in group 2. Clinical follow-up revealed that 92% of the patients were asymptomatic at 3 months after stenting compared with 6% before stenting (p less than 0.0001). Of the 13 patients who were symptomatic, nine underwent cardiac catheterization and, ultimately, successful elective coronary angioplasty or bypass surgery. We conclude that a high delivery success rate can be expected with this device and that clinical thrombosis is less frequent in anticoagulated patients than in nonanticoagulated patients. Furthermore, in this selected patient population, coronary stenting results in a low incidence of in-hospital and perioperative complications. Clinical success, defined by absence of symptoms, appears to be sustained at 3 months.

Angioplasty, Balloon, Coronary↗
PubMed1991

The chest X ray in Q-fever: a report on 69 cases from the 1989 West Midlands outbreak.

Acute and serial chest radiographic appearances of Q-fever in a large UK outbreak in the West Midlands are described. In 69 acute films (taken within 20 days of onset of illness), 10% of films were normal. Appearances in 62 abnormal films were varied and, in contrast to some previous reports, showed no features that might distinguish Q-fever pneumonia from pneumonias of other origins. Analysis of serial films in 47 cases showed that complete radiographic resolution frequently took up to 6 months, longer than has been described previously. Initial appearances deteriorated over the first 2 weeks of radiographic surveillance in 20% of cases. No relationship was found between the extent of radiographic change and the age of the patient or the presence or absence of respiratory symptoms. Age did not affect time to resolution.

Adult↗
PubMed1991

Mental dysfunction: a clinical pilot project in the elderly.

In recognizing that there will be an increase in the number of individuals with dementing illnesses well into the next century, the authors show how one institution is coping with this problem today. The authors outline an innovative approach to admission and discharge planning and monitoring of patients with irreversible dementias and behavioral problems. Nurses and other team members need a mechanism (ie, a flow chart) to monitor behavior and plot progress within an individualized program designed to meet the needs of dementia patients.

Aged↗
PubMed1991

T cells and asthma. I. Lymphocyte subpopulations and activation in allergic and nonallergic asthma.

Abnormalities of peripheral-blood lymphocyte subsets and activation markers were detected in patients with both allergic and nonallergic asthma. Most allergic asthmatics were characterized by increased numbers of IL-2R+ helper T cells and CD23+ B cells. In contrast, nonallergic asthmatics showed increased numbers of IL-2R+ and HLA-DR+ helper and cytotoxic T cells, and a clear redistribution from naive (CD45RA+) to memory (CD45RO+) cells. The number of IL-2R+ T cells correlated with the number of CD23+ B cells in allergic asthma. These changes in the distribution and activation state of T cells suggest an active role for T cells in the pathogenesis of both allergic and nonallergic asthma.

Antigens, CD↗
PubMed1991

T cells and asthma. II. Regulation of the eosinophilia of asthma by T cell cytokines.

Peripheral blood eosinophilia of both allergic and nonallergic asthmatics was found to correlate with blood T cell activation and lymphokine production. A close correlation was shown between the increase of IL-2 receptor expressing T cells and the number of eosinophils. These in vivo activated T cells spontaneously released factors that prolonged eosinophil survival in vitro. The T cell derived lymphokines IL-5, GM-CSF and IL-3 were demonstrated to be responsible for prolonged eosinophil survival in vitro, and were identified in T cell supernatants and sera from asthmatics. In summary, T cell derived cytokines play an important regulatory function towards eosinophils in asthma.

Asthma↗