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Biomedical subjects

A Franklin

Publications and source records attributed to A Franklin.

At least 91 records · Page 5Linked to original sources
PubMed1984

Antimicrobial drug resistance in porcine enterotoxigenic Escherichia coli of 0-group 149 and non-enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) strains (104) and 96 non-ETEC, all isolated from herds with piglet diarrhea in 1981 and 1982, were investigated with regard to antimicrobial drug resistance and colicinogeny. Eighty strains (77%) of the ETEC were drug resistant as compared to 66 strains (69%) of the non-ETEC. There were no significant differences between ETEC and non-ETEC in the frequencies of the drug resistance determinants investigated, except for tetracycline, to which 51 (49%) of the former and 30 (31%) of the latter strains were resistant (0.05 greater than P greater than 0.01). Of all strains 116 (58%) were resistant to streptomycin, 93 (47%) to sulphadimidin, 81 (41%) to tetracycline, 20 (10%) to trimethoprim, 14 (7%) to ampicillin, 11 (6%) to neomycin, 6 (3%) to chloramphenicol and none to nitrofurantoin. The frequencies of the different drug resistance determinants correlated well with the total amount of active substance of each drug used in farm animals in Sweden in 1981. Of the ETEC, 97 (93%) were colicinogenic whereas only 13 (14%) of the non-ETEC were colicinogenic.

Animals↗
PubMed1984

Determination of extracellular pH and tissue temperature in transplantable rat tumors by use of inductive loop telemetry.

Radiotelemetry was used to determine changes in extracellular pH and tissue temperature during tumor development in rats of an inbred WAB substrain. A progressive decrease in the pH of the tumor tissue compared with the pH level in control tissue was observed, so that by 4 days after tumor implantation the tumor tissue was about 0.4 pH units lower than control values. Thereafter, tumor pH rose progressively to reach a value comparable with control levels at 8 days, when the experiment was terminated. No significant difference was detected between the temperature in the tumor tissue and the temperature in the control tissue. Therefore, the observed changes in pH appeared to be independent of temperature. Studies on the rate of tumor cell proliferation during the experiments demonstrated a significant inverse relationship between tumor cell mitotic rate and pH, with the highest rates of cell proliferation occurring at the time of lowest pH values.

Animals↗
PubMed1984

Comparative Studies of Fluorescence from Mesophyll and Guard Cell Chloroplasts in Saxifraga cernua: Analysis of Fluorescence Kinetics as a Function of Excitation Intensity.

The chlorophyll fluorescence induction curves from mesophyll and guard cell chloroplasts of Saxifraga cernua, including both the fast (O to P, the transients involved in the rise in variable fluorescence) and slow (P to steady state fluorescence due to quenching) components, were characterized over a range of excitation intensities using microspectrophotometry (with epi-lumination) equipped with apertures designed to eliminate cross contamination of the fluorescence signal between the two chloroplast types. At low excitation intensities, the fast fluorescence kinetics from guard cell plastids showed an extended I to D phase and a more rapid appearance of P while minimal quenching from P to steady state fluorescence was observed compared to the transients from mesophyll chloroplasts suggesting a lower activity of photochemical (electron movement via carriers between donor and acceptor sites) and nonphotochemical (such as membrane conformational changes) events which regulate the fluorescence induction curve kinetics. As the excitation intensity was increased, the quenching rates of guard cells were faster at initiating conditions for photophosphorylation and the fast and slow fluorescence kinetics from guard cells resembled those of the mesophyll cells.Guard cell chloroplasts of S. cernua from intact epidermal peels showed a low temperature (77 K) fluorescence emission spectrum having three major peaks (at 685, 695, and 730 nanometers when excited at 440 nanometers) which were qualitatively similar to those in the spectrum obtained from mesophyll tissue.These data suggest that S. cernua guard cell chloroplast photosystems I and II contribute to light-dependent stomatal activity only at high light intensities.

Journal Article↗
PubMed1984

Some effects of radiation on the healing of transected mouse ear.

Both histological assessments and measurements of epidermal and dermal components are used to describe some effects of radiation on wound healing in mouse ear. A pattern of early wound closure followed by wound reopening was seen after doses of about 20 Gy and above. After 10 Gy X rays wound closure was comparable with that in unirradiated wounds but the nature of the tissue repair was different. The results suggested that the severity of radiation damage to epidermis is relatively unaffected by wounding but that the time course of expression of the radiation damage is appreciably accelerated. The observations are discussed in terms of their clinical relevance and of current radiobiological hypotheses.

Animals↗
PubMed1984

Mechanism of myocardial protection during blood-potassium cardioplegia: a comparison of crystalloid red cell and methemoglobin solutions.

The mechanism of myocardial protection provided by red blood cells was studied with a preparation of isolated, blood-perfused dog heart. Myocardial function, metabolism, and high-energy phosphate stores were determined before and at the end of cardioplegic arrest and after reperfusion. Cardioplegic solutions containing NaCl, KCl, and dextran (crystalloid; C) were compared, at 27 degrees C, with an identical solution containing 20% washed red cells (R) and a third solution in which the red cells were treated with 0.02M NaNO2, resulting in methemoglobin (M) formation or red cells able to buffer pH but unable to transport oxygen. Solutions were delivered at 15 min intervals during 2 hr of arrest and coronary effluent pH, PCO2, and lactate were measured. Both R and M solutions prevented the increases in effluent PCO2 and decreases observed in pH with C. On the other hand, mechanical, metabolic, and high-energy phosphate determinations revealed that marked protection was provided by R but not by M or C. Thus, myocardial protection provided by R at 27 degrees C is not the result of buffering but appears to be primarily the result of oxygen delivery by the red cells to the myocardium.

Animals↗
PubMed1983

Concurrent transfer and recombination between plasmids encoding for heat-stable enterotoxin and drug resistance in porcine enterotoxigenic Escherichia coli.

The frequency of and genetic mechanisms for simultaneous transfer of genes encoding for tetracycline and sulpha-streptomycin resistance, heat-labile (LT) and heat-stable (ST-mouse) enterotoxin production in porcine enterotoxigenic Escherichia coli to Escherichia coli K12 were investigated. Seven E. coli strains of 0-group 149 were studied by conjugation and transformation experiments. All strains transferred tetracycline-resistance plasmids at a high frequency. No interaction was observed between these plasmids and those encoding for LT production. However, most tetracycline-resistant recipient cells were ST-mouse+ following recombination events between plasmids encoding for colicin B and ST-mouse production and plasmids encoding for tetracycline resistance. Alternatively, when selecting for sulpha or streptomycin resistance a majority of the transconjugants were also ST-mouse+, as plasmids coding for sulpha and streptomycin were mobilized by the colicin B and ST-mouse encoding plasmid. Since the simultaneous transfer of genes encoding for drug resistance, colicin B and ST-mouse production are common events in vitro, they might also occur frequently in vivo during antibiotic selective pressure.

Animals↗
PubMed1983

The bi-articular hip prosthesis for fractures of the femoral neck--a preliminary report.

The bi-articular hip prosthesis (BHP), based on an original design by Bateman, is a bi-polar hemi-arthroplasty which seeks to reduce acetabular wear. We have used this prosthesis to treat 101 elderly patients with displaced intra-capsular fractures of the neck of the femur. The results of the first two years experience with this prosthesis are encouraging. Post-operative hip pain was not significant and did not interfere with mobility. The use of the antero-lateral approach to the hip joint prevented dislocation of the prosthesis, in contra-distinction to reports of series in which the Southern approach was used.

Aged↗
PubMed1983

Antimicrobial drug susceptibility of Staphylococcus aureus strains isolated from bovine milk.

The minimum inhibitory concentration (MIC) of ten antimicrobial drugs for 287 S. aureus strains recently isolated from bovine mastitic milk in different herds all over Sweden was determined. The minimum bactericidal concentration (MBC) of benzylpenicillin for 20 strains was determined. Thirty strains (10%) produced beta-lactamase. All strains were susceptible to oxacillin and neomycin, and more than 90% to streptomycin, trimethoprim-sulphamethoxazole chloramphenicol, erythromycin and tetracycline, whereas all were resistant to sulphamethoxazole. None of 20 strains investigated was tolerant to benzylpenicillin. However, S. aureus strains, isolated from bovine milk, should be tested for beta-lactamase production prior to treating mastitic cases with beta-lactam drugs.

Animals↗
PubMed1983

The effect of dietary restriction on thymus autonomy.

Fifty percent dietary restriction allows for continued body growth in young animals, whereas in older animals this dietary regime resulted in a 25% drop in body weight over a 10-wk period. This resulted in a relatively low rate of mitosis in the thymus tissue from young animals so that thymus size was maintained in proportion with body weight. There was no evidence to suggest that the thymus glands from dietary restricted young animals could not maintain their role in immune function. In the older animals dietary restriction resulted in depletion of thymic lymphocytes, despite a relatively high rate of cell division. It is postulated that this may be a result of stress caused by the dietary regime.

Age Factors↗
PubMed1982

Independent protection provided by red blood cells during cardioplegia.

Isolated, blood-perfused dog hearts were subjected to 2 hours of arrest at 27 degrees C and perfused at 15-minute intervals with either a potassium crystalloid cardioplegic solution (KCC) or an identical solution to which washed red blood cells were added (KrbcC). After reperfusion, hearts protected with KCC were easily defibrillated and systolic pressure returned to 62% of prearrest values 90 minutes after reperfusion. In hearts protected with KrbcC, systolic pressures recovered to 103% of prearrest values 15 minutes after reperfusion. Metabolic variables recovered more quickly in hearts perfused with KrbcC. Adenosine triphosphate did not decline with arrest in either group. Creatine phosphate values decreased with KCC and increased with KrbcC. The pH of the myocardial effluent fell to 6.48 during arrest with KCC and to 7.19 with KrbcC (p less than 0.001). Carbon dioxide tension increased with KCC, but decreased with KrbcC (p less than 0.001). Thus, marked improvement in recovery after 2 hours of arrest is seen with KrbcC. Protection beyond that provided by KCC appears solely due to the washed red cells, and may be the result of the buffering action of the red cell improved oxygen delivery.

Adenosine Triphosphate↗
PubMed1982

Effects of perfusion pressure on myocardial performance, metabolism, wall thickness, and compliance: comparison of the beating and fibrillating heart.

The effects of brief periods of graded reductions in perfusion pressure on normally beating and fibrillating hearts were examined. Mechanical and metabolic parameters were studied in the isolated, isovolumic (balloon in left ventricle), blood-perfused dog heart preparation. Experiments were carried out at perfusion pressures of 100, 75, 50, and 25 mm Hg, and comparisons of performance were made at the same ventricular volumes in the beating and fibrillating heart. A fall in perfusion pressure significantly decreased systolic performance in the beating heart. Diastolic pressure-volume relations were not altered by changes in perfusion pressure in the beating heart, but the fibrillating heart became significantly more compliant as perfusion pressure declined. Coronary blood flow and myocardial oxygen consumption were consistently higher during fibrillation than during sinus rhythm, and both parameters declined significantly at decreasing perfusion pressures. The fibrillating heart produced lactate at a perfusion pressure below 65 mm Hg, while the beating heart produced lactate at a perfusion pressure below 35 mm Hg. These studies demonstrate that brief periods of relatively modest decreases in perfusion pressure during ventricular fibrillation alter myocardial energy demand-supply relationships to result in ischemia of the fibrillating heart.

Animals↗
PubMed1981

Plasmids coding for enterotoxins, K88 antigen and colicins in porcine Escherichia coli strains of O-group 149.

This study was carried out to determine whether the strong epidemiological correlation observed in Sweden between production of the adhesin K88, the heat-stable (ST) and the heat-labile (LT) enterotoxins in E. coli strains of O-group 149 isolated from piglet diarrhea might be explained by linkage of their genetic determinants. From 22 different isolates plasmids coding for these virulence factors were investigated by conjugation and transduction experiments and analysis on agarose gels. The genes coding for ST production could be transferred by selection for antibiotic resistance, but behaved as transposable elements most often residing on a 55 Mdal plasmid coding for colicin B. The genes coding for raffinose fermentation and K88 antigen production were located on a 45 Mdal plasmid and the genes coding for LT production on plasmids within the 45-70 Mdal size. Thus the epidemiological importance and spread of this O-group in Sweden was explained by its stable content of two or three virulence plasmids, which could be transferred independently of one another.

Animals↗
PubMed1980

Anal cancer treated by fast neutron radiation.

Ten patients with anal cancer were treated with fast neutrons from the Medical Research Council Cyclotron at the Hammersmith Hospital. In all cases a temporary colostomy was established before treatment commenced. Three of the patients had advanced tumours that were extending into the pelvis; treatment for these patients was palliative and all died within 1 year. Four of the remaining 7 have normal anal function with no evidence of local recurrence of the tumour. Two others developed necrosis in the irradiated area and in another, the tumour recurred locally. The colostomy was re-established in 1 and the 2 others had abdominoperineal resections, after which wound healing was prolonged. A majority of the surviving patients have thus been able to avoid a permanent colostomy.

Adolescent↗