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Biomedical subjects

J A Elliott

Publications and source records attributed to J A Elliott.

At least 73 records · Page 4Linked to original sources
PubMed1987

Role of short photoperiod and cold exposure in regulating daily torpor in Djungarian hamsters.

1. Male and female Djungarian hamsters (Phodopus sungorus) were gonadectomized or sham-operated after 12 weeks of exposure to short photoperiods (10L:14D). Half of the animals were single housed and transferred to a cold environment (7 degrees C) at week 13 of short days and half were transferred to cold at week 21. The time courses of short photoperiod induced seasonal changes in body weight, pelage color stage, and daily torpor were monitored periodically until the experiment was terminated after 34 weeks of short days. 2. The total duration of short photoperiod exposure was of primary importance compared to the duration of cold exposure in regulating seasonal changes in the frequency of daily torpor, body weight and pelage color exhibited by male and female Djungarian hamsters; that is, the change from long to short days was much more effective as a seasonal time cue than was the onset of cold exposure. 3. Gonadectomy did not prevent the occurrence of seasonal torpor in hamsters of either sex, indicating that these cycles are regulated by a time measuring mechanism (seasonal clock) that is largely independent of the gonadal cycle. However, castration did influence certain aspects of the body weight and torpor cycles exhibited by male hamsters. 4. Some castrated animals showed a delay in terminating the torpor season lending further support to the hypothesis that the spontaneous recrudescence of the testes which occurs toward the end of the torpor season may play a role in the termination of torpor in males.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Susceptibility of relatively penicillin-resistant Streptococcus pneumoniae to newer cephalosporin antibiotics.

Antimicrobial susceptibilities were performed at the Centers for Disease Control on 3400 Streptococcus pneumoniae isolates that were collected during a national survey of serotype-distribution of pneumococci found in normally sterile body fluids. The results showed 126 isolates (3.7%) to be relatively resistant to penicillin (RPR). The RPR strains were tested for susceptibility to cefuroxime, ceftriaxone, cefotaxime, cefamandole, cefaclor, ceftazidime, and moxalactam. These newer generation cephalosporin drugs were tested either because of their ability to penetrate into the cerebrospinal fluid (CSF) or for their activity against pneumococci. Three hundred ninety-one pneumococci were tested with 179 resistant to at least one antimicrobial. The RPR strains were not categorically resistant to the cephalosporins but were fourfold more resistant to them than were the penicillin-susceptible strains. The three most effective antimicrobials in the study for RPR were cefuroxime, cefotaxime, and ceftriaxone [corrected]. Each gave MICs that were attainable in CSF for RPR. Fifty percent of the RPR were inhibited by 0.06 mg/ml and 90% by 0.25 micrograms/ml of these antimicrobials. The least effective were cefaclor, moxalactam, and ceftazidime.

Cephalosporins↗
PubMed1987

Separation of Haemophilus influenzae type b subtypes by numerical analysis.

Outer membrane proteins (OMPs) were prepared from 20 previously established subtypes of Haemophilus influenzae type b. Proteins were separated by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (11% acrylamide). Each lane in the gels contained two internal molecular weight standards. One central lane contained a range of molecular weight standards, which were used to calculate a molecular weight curve for each gel. Migration distances of the OMPs were determined with a soft laser-scanning densitometer, and the distances were normalized by using the mean migration distances of the internal standards. The protein patterns of all subtypes were compared by a recently described method (B.D. Plikaytis, G.M. Carlone, and B.B. Plikaytis, J. Gen. Microbiol. 132:2653-2660, 1986). All subtypes could be differentiated by this method. The ability to store and compare numerous OMP patterns from different isolates of H. influenzae type b, separated with a single homogeneous polyacrylamide gel, will facilitate the continued development of a subtyping system based on these proteins.

Bacterial Outer Membrane Proteins↗
PubMed1987

Metastatic patterns in small-cell lung cancer: correlation of autopsy findings with clinical parameters in 537 patients.

Postmortem material from 537 patients included in various protocols of intensive combination chemotherapy or chemoradiotherapy for the management of small-cell anaplastic carcinoma of the lung (SCLC) has been reviewed. Patterns of residual or recurrent disease were analyzed in relation to pretreatment clinical parameters. Residual primary tumor (P less than .05), regional lymph node involvement (P less than .01), hepatic (P less than .01), bone (P less than .05), and renal metastases (P less than .05) were all significantly less frequent among patients with initially limited-stage disease compared with extensively staged patients. The frequency of residual intrathoracic tumor and metastatic pattern did not significantly differ between partial responders (PRs) and nonresponders (NRs). Patients with limited disease achieving a complete remission had a lower frequency of intrathoracic tumor (P less than .001) at autopsy compared with limited-stage PRs. However, for extensive-stage patients the pattern of residual disease was essentially independent of tumor response. Prior surgery was associated with a reduced burden of metastases only in those who underwent a radical resection. The addition of radiotherapy to the primary tumor and mediastinum failed to modify the autopsy distribution of residual tumor compared with that in patients treated with chemotherapy alone. Metastatic patterns were similar with or without prophylactic abdominal radiotherapy, while prophylactic cranial irradiation (PCl) did not prevent the development of cerebral metastases in patients whose systemic response to treatment was either partial or nonexistent. However, a beneficial effect of PCl in compete responders (CRs) was not excluded.

Carcinoma, Small Cell↗
PubMed1986

Maternal transfer of photoperiodic information influences the photoperiodic response of prepubertal Djungarian hamsters (Phodopus sungorus sungorus).

Daylengths during the spring are repeated in reverse order in the autumn. For some photoperiodic species, a given photoperiod may be stimulatory for reproduction in the spring and inhibitory in the autumn. The mechanisms regulating this type of seasonal response have, until recently, remained a mystery. Horton (1984a) showed in Microtus montanus that the photoperiod experienced by the mother influences the gonadal development of her young after weaning. To determine if this phenomenon is characteristic of other photoperiodic rodents, adult Djungarian hamsters were paired on 16L:8D, 14L:10D, or 12L:12D. Young males born from these pairings were killed at 15, 28, and 34 days of age to assess gonadal development (testes weight). At 15 days testicular development was identical in all groups; by 28 days, however, males raised in 16L:8D or 14L:10D exhibited a greater degree of testicular development than those raised in 12L:12D. Next, females maintained on each of the three photoperiods throughout gestation were transferred, with their offspring, to the other two photoperiods at birth. Postnatal exposure to 14L:10D or 12L:12D inhibited testicular development in young that had been gestated on 16L:8D. Both 16L:8D and 14L:10D stimulated testicular growth in animals that had been gestated on 12L:12D or 14L:10D. Therefore, a) 16L:8D stimulates testicular growth in all animals, b) 12L:12D inhibits testicular growth in all animals, and c) the testicular response to 14L:10D depends on the photoperiod experienced by the mother during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Treatment of alveolar macrophages with cytochalasin D inhibits uptake and subsequent growth of Legionella pneumophila.

Legionella pneumophila multiplied rapidly in guinea pig and rat alveolar macrophages but failed to grow when phagocytic activity was inhibited by pretreatment with 0.5 or 1.0 microgram of cytochalasin D per ml. Attachment was not inhibited by cytochalasin D. No extracellular multiplication occurred when L. pneumophila were in close proximity to viable functional macrophages or even when the bacteria were attached to plasma membranes of the macrophages. Nonopsonized L. pneumophila were avidly phagocytized by alveolar macrophages. When bacteria were centrifuged onto a cell pellet, more than 85% of the phagocytes contained one or more bacteria within 15 min. In contrast, under the same conditions only approximately 15% of the macrophages contained nonopsonized Escherichia coli or Staphylococcus aureus. Phagocytosis of L. pneumophila by untreated guinea pig macrophages occurred by extension of pseudopodia around the bacteria in a classical manner. The failure of the bacteria to actively penetrate the phagocyte suggests that their intracellular survival must not depend on avoidance of a phagosome but rather on an inhibition of or resistance to subsequent microbicidal functions of the macrophage.

Animals↗
PubMed1985

An arteriovenous malformation in pregnancy: a case report and review of the literature.

A case is described of a young woman with progression of a macrofistulous arteriovenous malformation during pregnancy. This resulted in severe symptoms necessitating cesarean section, following which there was a dramatic postpartum recovery. The arteriovenous malformation was confirmed by angiography. The literature related to arteriovenous malformations in pregnancy is reviewed.

Adult↗
PubMed1984

Vindesine and cisplatin combination chemotherapy compared with vindesine as a single agent in the management of non-small cell lung cancer: a randomized study.

One hundred and five patients with inoperable non-small cell lung cancer were included in a randomized trial comparing the activity of vindesine as a single agent with the combination of vindesine and cisplatin. All patients were previously untreated and the majority (70%) had squamous carcinoma. The overall partial response rates in 88 evaluable patients were 7% for vindesine alone and 33% for the combined regime. There were no complete responders in either arm. The median survival of patients treated with vindesine and cisplatin was 11 months, compared with 4 months in those treated with vindesine alone (P = 0.008). Patients showing a partial or complete response to vindesine and cisplatin survived a median duration of 13 months, compared with 7 months for non-responders (P = 0.03). This survival benefit associated with the combination was particularly apparent for patients with ECOG performance status 0 or 1 (median survival greater than 18 months and 13 months respectively), locoregional disease (median survival 14 months) and squamous cell histology (median survival 13 months). Myelo-suppression was greater with the combination but was not a major treatment problem. Neurotoxicity, which was frequently dose-limiting, was of similar severity in both treatment groups. The results indicate that the combination of vindesine and cisplatin is superior to vindesine alone for remission induction in non-small cell lung cancer and confers a significant survival advantage compared with vindesine alone in patients with favourable prognostic factors.

Adenocarcinoma↗
PubMed1984

Pre-operative mediastinal evaluation in primary bronchial carcinoma--a review of staging investigations.

A review of staging investigations in the preoperative evaluation of mediastinal involvement in primary bronchial carcinoma is presented. The following conclusions are offered as guidelines for the use of mediastinal staging procedures in clinical practice: Surgical staging methods have the over-riding advantage of superior specificity over indirect imaging techniques. Where 67Ga-imaging or CT scanning are not available, routine pre-operative mediastinoscopy or, when appropriate, mediastinotomy will identify most patients with non-resectable disease but this approach entails a high proportion of true negative examinations. Radioisotope ventilation and perfusion lung imaging has no place in the pre-operative staging of lung cancer. Where the techniques are available, 67Ga-imaging and CT scanning have a use in selecting patients for mediastinal exploration. A negative mediastinal 67Ga scan or a negative CT examination suggest that mediastinal exploration will be unrewarding in the vast majority of cases and may be omitted prior to thoracotomy. A positive mediastinal 67Ga scan or the demonstration of abnormal mediastinal nodes by CT is an indication for mediastinal exploration which, if negative should be followed by thoracotomy.

Carcinoma, Bronchogenic↗
PubMed1983

A double-blind controlled study comparing temazepam with papaveretum as premedication for fibreoptic bronchoscopy.

One hundred patients undergoing routine fibreoptic bronchoscopy were randomly allocated to receive premedication with either intramuscular papaveretum or oral temazepam in a double-blind manner. They all received atropine before and oxygen during the procedure. Patients found the drugs equally acceptable in terms of discomfort, anxiety and the possibility of repeat bronchoscopy, but more had recall of the procedure with papaveretum. There was no difference in secretions, coughing, relaxation and consciousness, as assessed by the bronchoscopist, but patients who had received papaveretum were more cooperative. Arterial blood gases were performed before and 45 minutes after bronchoscopy. Those given papaveretum had a significant fall in mean arterial oxygen tension of 0.96 kPa, while there was no significant change in the temazepam group. There was also a small mean rise in arterial carbon dioxide tension in both groups, with the mean rise in the papaveretum group (0.625 kPa) being significantly higher than the temazepam group (0.2 kPa). Premedication with temazepam is a useful alternative to papaveretum and has the advantage of oral administration and causing less respiratory depression.

Anti-Anxiety Agents↗
PubMed1982

Mutagenicity of oil-shale ash.

3 oil-shale ash samples were extracted with solvents and analyzed for mutagenicity with a number of tests systems. In Salmonella typhimurium, the ash extracts were highly mutagenic with the Ames his reversion and the ara-resistant systems. Mutation induction by the ash in Salmonella was independent of metabolic activation and was of the frameshift type. These ash extracts showed a substantial killing effect, but failed to induced ad-3 reversion in Neurospora crassa, gene conversion and mitotic crossing-over in Saccharomyces cerevisiae and TGr mutation in cultured CHO cells.

Animals↗
PubMed1982

Virulence conversion of Legionella pneumophila serogroup 1 by passage in guinea pigs and embryonated eggs.

When virulent Legionella pneumophila is passaged on supplemented Mueller-Hinton agar, it remains virulent for guinea pigs and embryonated hen eggs for two passages. However, by the fifth passage the cultures become avirulent for guinea pigs. Flagella were not produced by L. pneumophila on the first passage on supplemented Mueller-Hinton agar. In contrast, 12 passages on charcoal-yeast extract agar did not result in the reduction of virulence or the loss of flagella of L. pneumophila. Growth in supplemented yeast extract broth or on Norit-A-filtered supplemented yeast extract agar also did not result in a reduction of the virulence of L. pneumophila. However, L. pneumophila did not produce flagella when grown on these two media. Thus, it appears that the production of flagella is not required for the virulence of L. pneumophila when administered by the intraperitoneal route of infection. A virulent flagellated form of L. pneumophila was recovered by passing an avirulent form six times in guinea pigs. When avirulent L. pneumophila was passaged 12 times in embryonated eggs, a nonflagellated form of the bacterium was recovered which had an increased virulence for guinea pigs and embryonated eggs. However, virulent forms were not recovered by passage of avirulent forms on commonly used laboratory media. These results support the suggestion that a suitable host is required for the selection of the virulent form of L. pneumophila from avirulent cultures.

Animals↗
PubMed1982

Autologous x-irradiated tumour cells and percutaneous BCG in operable lung cancer.

To determine the value of specific immunotherapy with adjuvant BCG in operable lung cancer, the immunological and clinical results of serial postoperative injections of autologous irradiated tumour cells and BCG were compared with those of a single preoperative injection of BCG in two randomly selected groups of patients undergoing resection of their tumours. There was a significant rise in tuberculin skin reactivity from seven weeks to 11 months after operation in the treated group. Actuarial curves for survival and freedom from tumour recurrence and median survival times showed an advantage for the treated patients who had stage I tumours, but these differences were significant only at the levels p = 0.07 - 0.09. Survival and duration of freedom from tumour recurrence was greater in autograft-treated patients whose skin responded to a weak test dose of dinitrochlorobenzene (DNCB) after sensitisation with 2% DNCB than in control DNCB-positive patients (p = 0.02). There were no significant differences in the actual proportion of patients from each group surviving at two years. The results show that this form of specific immunotherapy with adjuvant may have a beneficial effect in patients with stage I tumours and those who become sensitised to 2% DNCB after the first exposure.

Aged↗
PubMed1982

Effect of corticosteroids on sputum sol-phase protease inhibitors in chronic obstructive pulmonary disease.

Corticosteroids caused a reduction in the ratio of sol-phase sputum concentration to serum concentration of albumin in 12 patients with chronic obstructive bronchitis, suggesting a reduction in protein transudation. Alpha-1-antitrypsin values followed the same pattern as those of albumin in both the control and treatment periods, confirming the similar behaviour of the two proteins. The alpha 1-antichymotrypsin ratios were on average three times higher than those of albumin in the control period, confirming the presence of local mechanisms in the lung for preferentially concentrating this protein. The sputum-to-serum ratio of alpha 1-antichymotrypsin, however, rose during steroid treatment with the result that there was a selective increase in this protease inhibitor, which may be of potential benefit to such patients.

Bronchitis↗